United States

Department of Agriculture

Keys to

Soil Taxonomy

Tenth Edition, 2006

Keys to Soil Taxonomy

By Soil Survey Staff

United States Department of Agriculture

Natural Resources Conservation Service

Tenth Edition, 2006
ii

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Cover: Profile of a shallow Udipsamment with an abrupt wavy boundary between the C horizon and

bedrock. Depth to paralithic contact is 14 to 20 inches. Photo by John Kelley, Soil Scientist, Raleigh, North

Carolina.
iii

Table of Contents

Foreword .................................................................................................................................... v

Chapter 1: The Soils That We Classify .................................................................................. 1

Chapter 2: Differentiae for Mineral Soils and Organic Soils ................................................ 3

Chapter 3: Horizons and Characteristics Diagnostic for the Higher Categories ................... 5

Chapter 4: Identification of the Taxonomic Class of a Soil................................................. 31

Chapter 5: Alfisols ............................................................................................................... 35

Chapter 6: Andisols ............................................................................................................. 77

Chapter 7: Aridisols ............................................................................................................. 97

Chapter 8: Entisols............................................................................................................. 123

Chapter 9: Gelisols ............................................................................................................ 143

Chapter 10: Histosols........................................................................................................... 153

Chapter 11: Inceptisols ........................................................................................................ 159

Chapter 12: Mollisols .......................................................................................................... 191

Chapter 13: Oxisols ............................................................................................................. 235

Chapter 14: Spodosols ......................................................................................................... 251

Chapter 15: Ultisols ............................................................................................................. 261

Chapter 16: Vertisols ........................................................................................................... 283

Chapter 17: Family and Series Differentiae and Names ..................................................... 295

Chapter 18: Designations for Horizons and Layers ............................................................ 311

Appendix ............................................................................................................................... 317

Index ...................................................................................................................................... 325

v

Foreword

The publication of this edition of Keys to Soil Taxonomy (the 10th edition) coincides with

the 18th World Congress of Soil Science, to be held at Philadelphia, Pennsylvania, in July

2006. The last time the World Congress was hosted in the United States was in 1960 at

Madison, Wisconsin. At that time, Soil Classification: A Comprehensive System, 7th

Approximation was released for review and testing. The classification system was officially

adopted for use in the United States soil survey program in 1965. The first edition of Soil

Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys

was published in 1975. Over the years Soil Taxonomy has been modified and expanded to

reflect our increased knowledge of the world’s soils. After the first eight editions of the Keys

to Soil Taxonomy were released, the second edition of Soil Taxonomy was published in 1998.

Since then, the 9th edition of the keys was published in 2003, and now this 10th edition in

2006.

The publication Keys to Soil Taxonomy serves two purposes. It provides the taxonomic

keys necessary for the classification of soils in a form that can be used easily in the field. It

also acquaints users of the taxonomic system with recent changes in the system. This edition

of the Keys to Soil Taxonomy incorporates all changes approved since publication of the ninth

edition in 2003. We plan to continue issuing updated editions of the Keys to Soil Taxonomy as

changes warrant new editions.

The authors of the Keys to Soil Taxonomy are identified as the “Soil Survey Staff.” This

term is meant to include all of the soil classifiers in the National Cooperative Soil Survey

program and in the international community who have made significant contributions to the

improvement of the taxonomic system.

Micheal L. Golden

Director, Soil Survey Division

Natural Resources Conservation Service

1

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The word “soil,” like many common words, has several

meanings. In its traditional meaning, soil is the natural medium

for the growth of land plants, whether or not it has discernible

soil horizons. This meaning is still the common understanding

of the word, and the greatest interest in soil is centered on this

meaning. People consider soil important because it supports

plants that supply food, fibers, drugs, and other wants of

humans and because it filters water and recycles wastes. Soil

covers the earth’s surface as a continuum, except on bare rock,

in areas of perpetual frost or deep water, or on the bare ice of

glaciers. In this sense, soil has a thickness that is determined by

the rooting depth of plants.

Soil in this text is a natural body comprised of solids

(minerals and organic matter), liquid, and gases that occurs on

the land surface, occupies space, and is characterized by one or

both of the following: horizons, or layers, that are

distinguishable from the initial material as a result of additions,

losses, transfers, and transformations of energy and matter or

the ability to support rooted plants in a natural environment.

This definition is expanded from the 1975 version of Soil

Taxonomy to include soils in areas of Antarctica where

pedogenesis occurs but where the climate is too harsh to

support the higher plant forms.

The upper limit of soil is the boundary between soil and air,

shallow water, live plants, or plant materials that have not begun

to decompose. Areas are not considered to have soil if the

surface is permanently covered by water too deep (typically

more than 2.5 m) for the growth of rooted plants. The

horizontal boundaries of soil are areas where the soil grades to

deep water, barren areas, rock, or ice. In some places the

separation between soil and nonsoil is so gradual that clear

distinctions cannot be made.

The lower boundary that separates soil from the nonsoil

underneath is most difficult to define. Soil consists of the

horizons near the earth’s surface that, in contrast to the

underlying parent material, have been altered by the interactions

of climate, relief, and living organisms over time. Commonly,

soil grades at its lower boundary to hard rock or to earthy

materials virtually devoid of animals, roots, or other marks of

biological activity. The lowest depth of biological activity,

however, is difficult to discern and is often gradual. For

purposes of classification, the lower boundary of soil is

arbitrarily set at 200 cm. In soils where either biological activity

or current pedogenic processes extend to depths

greater than 200 cm, the lower limit of the soil for classification

purposes is still 200 cm. In some instances the more weakly

cemented bedrocks (paralithic materials, defined later) have

been described and used to differentiate soil series (series

control section, defined later), even though the paralithic

materials below a paralithic contact are not considered soil in

the true sense. In areas where soil has thin cemented horizons

that are impermeable to roots, the soil extends as deep as the

deepest cemented horizon, but not below 200 cm. For certain

management goals, layers deeper than the lower boundary of

the soil that is classified (200 cm) must also be described if they

affect the content and movement of water and air or other

interpretative concerns.

In the humid tropics, earthy materials may extend to a depth

of many meters with no obvious changes below the upper 1 or 2

m, except for an occasional stone line. In many wet soils,

gleyed soil material may begin a few centimeters below the

surface and, in some areas, continue down for several meters

apparently unchanged with increasing depth. The latter

condition can arise through the gradual filling of a wet basin in

which the A horizon is gradually added to the surface and

becomes gleyed beneath. Finally, the A horizon rests on a thick

mass of gleyed material that may be relatively uniform. In both

of these situations, there is no alternative but to set the lower

limit of soil at the arbitrary limit of 200 cm.

Soil, as defined in this text, does not need to have discernible

horizons, although the presence or absence of horizons and

their nature are of extreme importance in soil classification.

Plants can be grown under glass in pots filled with earthy

materials, such as peat or sand, or even in water. Under proper

conditions all these media are productive for plants, but they are

nonsoil here in the sense that they cannot be classified in the

same system that is used for the soils of a survey area, county,

or even nation. Plants even grow on trees, but trees are regarded

as nonsoil.

Soil has many properties that fluctuate with the seasons. It

may be alternately cold and warm or dry and moist. Biological

activity is slowed or stopped if the soil becomes too cold or too

dry. The soil receives flushes of organic matter when leaves fall

or grasses die. Soil is not static. The pH, soluble salts, amount

The Soils That We Classify

CHAPTER 1
2

of organic matter and carbon-nitrogen ratio, numbers of microorganisms, soil fauna, temperature, and moisture all change

with the seasons as well as with more extended periods of time.

Soil must be viewed from both the short-term and long-term

perspective.

Buried Soils

A buried soil is covered with a surface mantle of new soil

material that either is 50 cm or more thick or is 30 to 50 cm

thick and has a thickness that equals at least half the total

thickness of the named diagnostic horizons that are preserved in

the buried soil. A surface mantle of new material that does not

have the required thickness for buried soils can be used to

establish a phase of the mantled soil or even another soil series

if the mantle affects the use of the soil.

Any horizons or layers underlying a plaggen epipedon are

considered to be buried.

A surface mantle of new material, as defined here, is largely

unaltered, at least in the lower part. It may have a diagnostic

surface horizon (epipedon) and/or a cambic horizon, but it has

no other diagnostic subsurface horizons, all defined later.

However, there remains a layer 7.5 cm or more thick that fails

the requirements for all diagnostic horizons, as defined later,

overlying a horizon sequence that can be clearly identified as

the solum of a buried soil in at least half of each pedon. The

recognition of a surface mantle should not be based only on

studies of associated soils.
3

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Soil taxonomy differentiates between mineral soils and

organic soils. To do this, first, it is necessary to distinguish

mineral soil material from organic soil material. Second, it is

necessary to define the minimum part of a soil that should be

mineral if a soil is to be classified as a mineral soil and the

minimum part that should be organic if the soil is to be

classified as an organic soil.

Nearly all soils contain more than traces of both mineral and

organic components in some horizons, but most soils are

dominantly one or the other. The horizons that are less than

about 20 to 35 percent organic matter, by weight, have

properties that are more nearly those of mineral than of organic

soils. Even with this separation, the volume of organic matter at

the upper limit exceeds that of the mineral material in the fineearth fraction.

Mineral Soil Material

Mineral soil material (less than 2.0 mm in diameter) either:

1. Is saturated with water for less than 30 days (cumulative)

per year in normal years and contains less than 20 percent (by

weight) organic carbon; or

2. Is saturated with water for 30 days or more cumulative in

normal years (or is artificially drained) and, excluding live

roots, has an organic carbon content (by weight) of:

a. Less than 18 percent if the mineral fraction contains 60

percent or more clay; or

b. Less than 12 percent if the mineral fraction contains no

clay; or

c. Less than 12 + (clay percentage multiplied by 0.1)

percent if the mineral fraction contains less than 60 percent

clay.

Organic Soil Material

Soil material that contains more than the amounts of organic

carbon described above for mineral soil material is considered

organic soil material.

In the definition of mineral soil material above, material that

has more organic carbon than in item 1 is intended to include

what has been called litter or an O horizon. Material that has

more organic carbon than in item 2 has been called peat or

muck. Not all organic soil material accumulates in or under

water. Leaf litter may rest on a lithic contact and support forest

vegetation. The soil in this situation is organic only in the sense

that the mineral fraction is appreciably less than half the weight

and is only a small percentage of the volume of the soil.

Distinction Between Mineral Soils and Organic

Soils

Most soils are dominantly mineral material, but many

mineral soils have horizons of organic material. For simplicity

in writing definitions of taxa, a distinction between what is

meant by a mineral soil and an organic soil is useful. To apply

the definitions of many taxa, one must first decide whether the

soil is mineral or organic. An exception is the Andisols (defined

later). These generally are considered to consist of mineral

soils, but some may be organic if they meet other criteria for

Andisols. Those that exceed the organic carbon limit defined for

mineral soils have a colloidal fraction dominated by shortrange-order minerals or aluminum-humus complexes. The

mineral fraction in these soils is believed to give more control to

the soil properties than the organic fraction. Therefore, the soils

are included with the Andisols rather than the organic soils

defined later as Histosols.

If a soil has both organic and mineral horizons, the relative

thickness of the organic and mineral soil materials must be

considered. At some point one must decide that the mineral

horizons are more important. This point is arbitrary and

depends in part on the nature of the materials. A thick layer of

sphagnum has a very low bulk density and contains less organic

matter than a thinner layer of well-decomposed muck. It is

much easier to measure the thickness of layers in the field than

it is to determine tons of organic matter per hectare. The

definition of a mineral soil, therefore, is based on the thickness

of the horizons, or layers, but the limits of thickness must vary

with the kinds of materials. The definition that follows is

intended to classify as mineral soils those that have both thick

mineral soil layers and no more organic material than the

amount permitted in the histic epipedon, which is defined in

chapter 3.

In the determination of whether a soil is organic or mineral,

the thickness of horizons is measured from the surface of the

soil whether that is the surface of a mineral or an organic

CHAPTER 2

Differentiae for Mineral Soils1 and Organic Soils

1 Mineral soils include all soils except the suborder Histels and the order Histosols.
4

horizon, unless the soil is buried as defined in chapter 1. Thus,

any O horizon at the surface is considered an organic horizon if

it meets the requirements of organic soil material as defined

later, and its thickness is added to that of any other organic

horizons to determine the total thickness of organic soil

materials.

Definition of Mineral Soils

Mineral soils are soils that have either of the following:

1. Mineral soil materials that meet one or more of the

following:

a. Overlie cindery, fragmental, or pumiceous materials and/

or have voids2 that are filled with 10 percent or less organic

materials and directly below these materials have either a

densic, lithic, or paralithic contact; or

b. When added with underlying cindery, fragmental, or

pumiceous materials, total more than 10 cm between the soil

surface and a depth of 50 cm; or

c. Constitute more than one-third of the total thickness of

the soil to a densic, lithic, or paralithic contact or have a total

thickness of more than 10 cm; or

d. If they are saturated with water for 30 days or more per

year in normal years (or are artificially drained) and have

organic materials with an upper boundary within 40 cm of

the soil surface, have a total thickness of either:

(1) Less than 60 cm if three-fourths or more of their

volume consists of moss fibers or if their bulk density,

moist, is less than 0.1 g/cm3; or

(2) Less than 40 cm if they consist either of sapric or

hemic materials, or of fibric materials with less than

three-fourths (by volume) moss fibers and a bulk density,

moist, of 0.1 g/cm3 or more; or

2. More than 20 percent, by volume, mineral soil materials

from the soil surface to a depth of 50 cm or to a glacic layer or

a densic, lithic, or paralithic contact, whichever is shallowest;

and

a. Permafrost within 100 cm of the soil surface; or

b. Gelic materials within 100 cm of the soil surface and

permafrost within 200 cm of the soil surface.

Definition of Organic Soils

Organic soils have organic soil materials that:

1. Do not have andic soil properties in 60 percent or more of

the thickness between the soil surface and either a depth of 60

cm or a densic, lithic, or paralithic contact or duripan if

shallower; and

2. Meet one or more of the following:

a. Overlie cindery, fragmental, or pumiceous materials

and/or fill their interstices2 and directly below these

materials have a densic, lithic, or paralithic contact; or

b. When added with the underlying cindery, fragmental,

or pumiceous materials, total 40 cm or more between the

soil surface and a depth of 50 cm; or

c. Constitute two-thirds or more of the total thickness of

the soil to a densic, lithic, or paralithic contact and have no

mineral horizons or have mineral horizons with a total

thickness of 10 cm or less; or

d. Are saturated with water for 30 days or more per year in

normal years (or are artificially drained), have an upper

boundary within 40 cm of the soil surface, and have a total

thickness of either:

(1) 60 cm or more if three-fourths or more of their

volume consists of moss fibers or if their bulk density,

moist, is less than 0.1 g/cm3; or

(2) 40 cm or more if they consist either of sapric or

hemic materials, or of fibric materials with less than

three-fourths (by volume) moss fibers and a bulk density,

moist, of 0.1 g/cm3 or more; or

e. Are 80 percent or more, by volume, from the soil surface

to a depth of 50 cm or to a glacic layer or a densic, lithic, or

paralithic contact, whichever is shallowest.

It is a general rule that a soil is classified as an organic soil

(Histosol) if more than half of the upper 80 cm (32 in) of the

soil is organic or if organic soil material of any thickness rests

on rock or on fragmental material having interstices filled with

organic materials.

2 Materials that meet the definition of cindery, fragmental, or pumiceous but have more

than 10 percent, by volume, voids that are filled with organic soil materials are considered

to be organic soil materials.
5

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This chapter defines the horizons and characteristics of

both mineral and organic soils. It is divided into three parts—

horizons and characteristics diagnostic for mineral soils,

characteristics diagnostic for organic soils, and horizons and

characteristics diagnostic for both mineral and organic soils.

The horizons and characteristics defined below are not in a

key format. Some diagnostic horizons are mutually exclusive,

and some are not. An umbric epipedon, for example, could

not also be a mollic epipedon. A kandic horizon with clay films,

however, could also meet the definition of an argillic horizon.

Horizons and Characteristics

Diagnostic for Mineral Soils

The criteria for some of the following horizons and

characteristics, such as histic and folistic epipedons, can be met

in organic soils. They are diagnostic, however, only for the

mineral soils.

Diagnostic Surface Horizons:

The Epipedon

The epipedon (Gr. epi, over, upon, and pedon, soil) is a

horizon that forms at or near the surface and in which most of

the rock structure has been destroyed. It is darkened by organic

matter or shows evidence of eluviation, or both. Rock structure

as used here and in other places in this taxonomy includes fine

stratification (less than 5 mm) in unconsolidated sediments

(eolian, alluvial, lacustrine, or marine) and saprolite derived

from consolidated rocks in which the unweathered minerals and

pseudomorphs of weathered minerals retain their relative

positions to each other.

Any horizon may be at the surface of a truncated soil. The

following section, however, is concerned with eight diagnostic

horizons that have formed at or near the soil surface. These

horizons can be covered by a surface mantle of new soil

material. If the surface mantle has rock structure, the top of the

epipedon is considered the soil surface unless the mantle meets

the definition of buried soils in chapter 1. If the soil includes a

buried soil, the epipedon, if any, is at the soil surface and the

epipedon of the buried soil is considered a buried epipedon and

is not considered in selecting taxa unless the keys specifically

indicate buried horizons, such as those in Thapto-Histic

subgroups. A soil with a mantle thick enough to have a buried

soil has no epipedon if the soil has rock structure to the surface

or has an Ap horizon less than 25 cm thick that is underlain by

soil material with rock structure. The melanic epipedon (defined

below) is unique among epipedons. It forms commonly in

volcanic deposits and can receive fresh deposits of ash.

Therefore, this horizon is permitted to have layers within and

above the epipedon that are not part of the melanic epipedon.

A recent alluvial or eolian deposit that retains stratifications

(5 mm or less thick) or an Ap horizon directly underlain by

such stratified material is not included in the concept of the

epipedon because time has not been sufficient for soil-forming

processes to erase these transient marks of deposition and for

diagnostic and accessory properties to develop.

An epipedon is not the same as an A horizon. It may include

part or all of an illuvial B horizon if the darkening by organic

matter extends from the soil surface into or through the B

horizon.

Anthropic Epipedon

Required Characteristics

The anthropic epipedon consists of mineral soil material that

shows some evidence of disturbance by human activity. After

mixing of the upper 18 cm of the mineral soil, or of the whole

mineral soil if its depth to a densic, lithic, or paralithic contact,

a petrocalcic horizon, or a duripan (all defined below) is less

than 18 cm, the anthropic epipedon has the following

properties:

1. When dry, either or both:

a. Structural units with a diameter of 30 cm or less or

secondary structure with a diameter of 30 cm or less; or

b. A moderately hard or softer rupture-resistance class; and

2. Rock structure, including fine (less than 5 mm)

stratifications, in less than one-half of the volume of all parts;

and

3. One of the following:

a. Both of the following:

(1) Dominant colors with a value of 3 or less, moist, and

of 5 or less, dry; and

(2) Dominant colors with chroma of 3 or less, moist; or

CHAPTER 3

Horizons and Characteristics Diagnostic for the Higher Categories
6 Keys to Soil Taxonomy

b. A fine-earth fraction that has a calcium carbonate

equivalent of 15 to 40 percent and colors with value and

chroma of 3 or less, moist; or

c. A fine-earth fraction that has a calcium carbonate

equivalent of 40 percent or more and a color value, moist, of

5 or less; and

4. An organic-carbon content of:

a. 2.5 percent or more if the epipedon has a color value,

moist, of 4 or 5; or

b. 0.6 percent more (absolute) than that of the C horizon (if

one occurs) if the mollic epipedon has a color value less than

1 Munsell unit lower or chroma less than 2 units lower (both

moist and dry) than the C horizon; or

c. 0.6 percent or more and the epipedon does not meet the

qualifications in 4-a or 4-b above; and

5. The minimum thickness of the epipedon is as follows:

a. 25 cm if:

 (1) The texture of the epipedon is loamy fine sand or

coarser throughout; or

(2) There are no underlying diagnostic horizons

(defined below), and the organic-carbon content of the

underlying materials decreases irregularly with increasing

depth; or

(3) Both of the following are 75 cm or more below the

mineral soil surface:

(a) The lower boundary of the deepest of any argillic,

cambic, natric, oxic, or spodic horizon (defined

below); and

(b) The upper boundary of the shallowest of any

calcic horizon, petrocalcic horizon, duripan, fragipan,

or identifiable secondary carbonates; or

b. 10 cm if the epipedon is finer than loamy fine sand

(when mixed) and is directly above a densic, lithic, or

paralithic contact, a petrocalcic horizon, or a duripan; or

c. 18 to 25 cm and the thickness is one-third or more of the

total thickness between the mineral soil surface and:

(1) The upper boundary of the shallowest of any

identifiable secondary carbonates, a calcic horizon, a

petrocalcic horizon, a duripan, or a fragipan; or

(2) The lower boundary of the deepest of any

argillic, cambic, natric, oxic, or spodic horizon; or

d. 18 cm if none of the above conditions apply.

6. One or both of the following:

a. Has a phosphate content of 1,500 or more milligrams

per kilogram by citric-acid extraction; and

(1) The phosphorous content decreases regularly with

increasing depth below the epipedon; and

(2) Phosporous is not in the form of nodules; or

b. All parts of the epipedon are moist for less than 90 days

(cumulative) in normal years during times when the soil

temperature at a depth of 50 cm is 5 o

C or higher, if the soil

is not irrigated; and

7. The n value (defined below) is less than 0.7.

Folistic Epipedon

Required Characteristics

The folistic epipedon is defined as a layer (one or more

horizons) that is saturated for less than 30 days (cumulative) in

normal years (and is not artificially drained) and either:

1. Consists of organic soil material that:

a. Is 20 cm or more thick and either contains 75 percent or

more (by volume) Sphagnum fibers or has a bulk density,

moist, of less than 0.1; or

b. Is 15 cm or more thick; or

2. Is an Ap horizon that, when mixed to a depth of 25 cm, has

an organic-carbon content (by weight) of:

a. 16 percent or more if the mineral fraction contains 60

percent or more clay; or

b. 8 percent or more if the mineral fraction contains no

clay; or

c. 8 + (clay percentage divided by 7.5) percent or more if

the mineral fraction contains less than 60 percent clay.

Most folistic epipedons consist of organic soil material

(defined in chapter 2). Item 2 provides for a folistic epipedon

that is an Ap horizon consisting of mineral soil material.

Histic Epipedon

Required Characteristics

The histic epipedon is a layer (one or more horizons) that is

characterized by saturation (for 30 days or more, cumulative)

and reduction for some time during normal years (or is

artificially drained) and either:

1. Consists of organic soil material that:

a. Is 20 to 60 cm thick and either contains 75 percent or

more (by volume) Sphagnum fibers or has a bulk density,

moist, of less than 0.1; or

b. Is 20 to 40 cm thick; or

2. Is an Ap horizon that, when mixed to a depth of 25 cm, has

an organic-carbon content (by weight) of:
Horizons and Characteristics Diagnostic for the Higher Categories 7

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a. 16 percent or more if the mineral fraction contains 60

percent or more clay; or

b. 8 percent or more if the mineral fraction contains no

clay; or

c. 8 + (clay percentage divided by 7.5) percent or more if

the mineral fraction contains less than 60 percent clay.

Most histic epipedons consist of organic soil material

(defined in chapter 2). Item 2 provides for a histic epipedon that

is an Ap horizon consisting of mineral soil material. A histic

epipedon consisting of mineral soil material can also be part of

a mollic or umbric epipedon.

Melanic Epipedon

Required Characteristics

The melanic epipedon has both of the following:

1. An upper boundary at, or within 30 cm of, either the

mineral soil surface or the upper boundary of an organic layer

with andic soil properties (defined below), whichever is

shallower; and

2. In layers with a cumulative thickness of 30 cm or more

within a total thickness of 40 cm, all of the following:

a. Andic soil properties throughout; and

b. A color value, moist, and chroma (Munsell designations)

of 2 or less throughout and a melanic index of 1.70 or less

throughout; and

c. 6 percent or more organic carbon as a weighted average

and 4 percent or more organic carbon in all layers.

Mollic Epipedon

Required Characteristics

The mollic epipedon consists of mineral soil materials and,

after mixing of the upper 18 cm of the mineral soil or of the

whole mineral soil if its depth to a densic, lithic, or paralithic

contact, a petrocalcic horizon, or a duripan (all defined below)

is less than 18 cm, has the following properties:

1. When dry, either or both:

a. Structural units with a diameter of 30 cm or less

or secondary structure with a diameter of 30 cm or less;

or

b. A moderately hard or softer rupture-resistance class;

and

2. Rock structure, including fine (less than 5 mm)

stratifications, in less than one-half of the volume of all parts;

and

3. One of the following:

a. Both of the following:

(1) Dominant colors with a value of 3 or less, moist, and

of 5 or less, dry; and

(2) Dominant colors with chroma of 3 or less, moist; or

b. A fine-earth fraction that has a calcium carbonate

equivalent of 15 to 40 percent and colors with a value and

chroma of 3 or less, moist; or

c. A fine-earth fraction that has a calcium carbonate

equivalent of 40 percent or more and a color value, moist, of

5 or less; and

4. A base saturation (by NH4

OAc) of 50 percent or more

throughout; and

5. An organic-carbon content of:

a. 2.5 percent or more if the epipedon has a color value,

moist, of 4 or 5; or

b. 0.6 percent (absolute) more than that of the C horizon (if

one occurs) if the mollic epipedon has a color value less than

1 Munsell unit lower or chroma less than 2 units lower (both

moist and dry) than the C horizon; or

c. 0.6 percent or more and the epipedon does not meet the

qualifications in 5-a or 5-b above; and

6. The minimum thickness of the epipedon is as follows:

a. 25 cm if:

(1) The texture of the epipedon is loamy fine sand or

coarser throughout; or

(2) There are no underlying diagnostic horizons

(defined below) and the organic-carbon content of the

underlying materials decreases irregularly with increasing

depth; or

(3) Both of the following are 75 cm or more below the

mineral soil surface:

(a) The lower boundary of the deepest of any argillic,

cambic, natric, oxic, or spodic horizon (defined

below); and

(b) The upper boundary of the shallowest of any

petrocalcic horizon, duripan, fragipan, or identifiable

secondary carbonates; or

b. 10 cm if the epipedon is finer than loamy fine sand

(when mixed) and it is directly above a densic, lithic, or

paralithic contact, a petrocalcic horizon, or a duripan; or

c. 18 to 25 cm and the thickness is one-third or more of the

total thickness between the mineral soil surface and:

(1) The upper boundary of the shallowest of any

identifiable secondary carbonates or a calcic horizon,

petrocalcic horizon, duripan, or fragipan; or
8 Keys to Soil Taxonomy

(2) The lower boundary of the deepest of any argillic,

cambic, natric, oxic, or spodic horizon; or

d. 18 cm if none of the above conditions apply; and

7. Phosphate:

a. Content less than 1,500 milligrams per kilogram by

citric-acid extraction; or

b. Content decreasing irregularly with increasing depth

below the epipedon; or

c. Nodules are within the epipedon; and

8. Some part of the epipedon is moist for 90 days or more

(cumulative) in normal years during times when the soil

temperature at a depth of 50 cm is 5 oC or higher, if the soil is

not irrigated; and

9. The n value (defined below) is less than 0.7.

Ochric Epipedon

The ochric epipedon fails to meet the definitions for any of

the other seven epipedons because it is too thin or too dry, has

too high a color value or chroma, contains too little organic

carbon, has too high an n value or melanic index, or is both

massive and hard or harder when dry. Many ochric epipedons

have either a Munsell color value of 4 or more, moist, and 6 or

more, dry, or chroma of 4 or more, or they include an A or Ap

horizon that has both low color values and low chroma but is

too thin to be recognized as a mollic or umbric epipedon (and

has less than 15 percent calcium carbonate equivalent in the

fine-earth fraction). Ochric epipedons also include horizons of

organic materials that are too thin to meet the requirements for a

histic or folistic epipedon.

The ochric epipedon includes eluvial horizons that are at or

near the soil surface, and it extends to the first underlying

diagnostic illuvial horizon (defined below as an argillic, kandic,

natric, or spodic horizon). If the underlying horizon is a B

horizon of alteration (defined below as a cambic or oxic

horizon) and there is no surface horizon that is appreciably

darkened by humus, the lower limit of the ochric epipedon is

the lower boundary of the plow layer or an equivalent depth (18

cm) in a soil that has not been plowed. Actually, the same

horizon in an unplowed soil may be both part of the epipedon

and part of the cambic horizon; the ochric epipedon and the

subsurface diagnostic horizons are not all mutually exclusive.

The ochric epipedon does not have rock structure and does not

include finely stratified fresh sediments, nor can it be an Ap

horizon directly overlying such deposits.

Plaggen Epipedon

The plaggen epipedon is a human-made surface layer 50 cm

or more thick that has been produced by long-continued

manuring.

A plaggen epipedon can be identified by several means.

Commonly, it contains artifacts, such as bits of brick and

pottery, throughout its depth. There may be chunks of diverse

materials, such as black sand and light gray sand, as large as the

size held by a spade. The plaggen epipedon normally shows

spade marks throughout its depth and also remnants of thin

stratified beds of sand that were probably produced on the soil

surface by beating rains and were later buried by spading. A

map unit delineation of soils with plaggen epipedons would

tend to have straight-sided rectangular bodies that are higher

than the adjacent soils by as much as or more than the thickness

of the plaggen epipedon.

Required Characteristics

The plaggen epipedon consists of mineral soil materials and

has the following:

1. Locally raised land surfaces; and one or both of the

following:

a. Artifacts; or

b. Spade marks below a depth of 30 cm; and

2. Colors with a value of 4 or less, moist, 5 or less, dry, and

chroma of 2 or less; and

3. An organic-carbon content of 0.6 percent or more; and

4. A thickness of 50 cm or more; and

5. Some part of the epipedon that is moist for 90 days or more

(cumulative) in normal years during times when the soil

temperature at a depth of 50 cm is 5 o

C or higher, if the soil is

not irrigated.

Umbric Epipedon

Required Characteristics

The umbric epipedon consists of mineral soil materials and,

after mixing of the upper 18 cm of the mineral soil or of the

whole mineral soil if its depth to a densic, lithic, or paralithic

contact, a petrocalcic horizon, or a duripan (all defined below)

is less than 18 cm, has the following properties:

1. When dry, either or both:

a. Structural units with a diameter of 30 cm or less or

secondary structure with a diameter of 30 cm or less; or

b. A moderately hard or softer rupture-resistance class; and

2. Rock structure, including fine (less than 5 mm)

stratifications, in less than one-half of the volume of all parts;

and

3. Both of the following:

a. Dominant colors with a value of 3 or less, moist, and of

5 or less, dry; and
Horizons and Characteristics Diagnostic for the Higher Categories 9

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b. Dominant colors with chroma of 3 or less, moist; and

4. A base saturation (by NH4OAc) of less than 50 percent in

some or all parts; and

5. An organic-carbon content of:

a. 0.6 percent (absolute) more than that of the C horizon (if

one occurs) if the umbric epipedon has a color value less

than 1 Munsell unit lower or chroma less than 2 units lower

(both moist and dry) than the C horizon; or

b. 0.6 percent or more and the epipedon does not meet the

qualifications in 5-a above; and

6. The minimum thickness of the epipedon is as follows:

a. 25 cm if:

(1) The texture of the epipedon is loamy fine sand or

coarser throughout; or

(2) There are no underlying diagnostic horizons

(defined below) and the organic-carbon content of the

underlying materials decreases irregularly with increasing

depth; or

(3) Both of the following are 75 cm or more below the

mineral soil surface:

(a) The lower boundary of the deepest of any argillic,

cambic, natric, oxic, or spodic horizon (defined

below); and

(b) The upper boundary of the shallowest of any

petrocalcic horizon, duripan, fragipan, or identifiable

secondary carbonates; or

b. 10 cm if the epipedon is finer than loamy fine sand

(when mixed) and it is directly above a densic, lithic, or

paralithic contact, a petrocalcic horizon, or a duripan; or

c. 18 to 25 cm and the thickness is one-third or more of the

total thickness between the mineral soil surface and:

(1) The upper boundary of the shallowest of any

identifiable secondary carbonates or a calcic horizon,

petrocalcic horizon, duripan, or fragipan; or

(2) The lower boundary of the deepest of any argillic,

cambic, natric, oxic, or spodic horizon; or

d. 18 cm if none of the above conditions apply; and

7. Phosphate:

a. Content less than 1,500 milligrams per kilogram by

citric-acid extraction; or

b. Content decreasing irregularly with increasing depth

below the epipedon; or

c. Nodules are within the epipedon; and

8. Some part of the epipedon is moist for 90 days or more

(cumulative) in normal years during times when the soil

temperature at a depth of 50 cm is 5 oC or higher, if the soil is

not irrigated; and

9. The n value (defined below) is less than 0.7; and

10. The umbric epipedon does not have the artifacts, spade

marks, and raised surfaces that are characteristic of the plaggen

epipedon.

Diagnostic Subsurface Horizons

The horizons described in this section form below the

surface of the soil, although in some areas they form directly

below a layer of leaf litter. They may be exposed at the surface

by truncation of the soil. Some of these horizons are generally

regarded as B horizons, some are considered B horizons by

many but not all pedologists, and others are generally regarded

as parts of the A horizon.

Agric Horizon

The agric horizon is an illuvial horizon that has formed

under cultivation and contains significant amounts of illuvial

silt, clay, and humus.

Required Characteristics

The agric horizon is directly below an Ap horizon and has

the following properties:

1. A thickness of 10 cm or more and either:

a. 5 percent or more (by volume) wormholes, including

coatings that are 2 mm or more thick and have a value,

moist, of 4 or less and chroma of 2 or less; or

b. 5 percent or more (by volume) lamellae that have a

thickness of 5 mm or more and have a value, moist, of 4 or

less and chroma of 2 or less.

Albic Horizon

The albic horizon is an eluvial horizon, 1.0 cm or more

thick, that has 85 percent or more (by volume) albic materials

(defined below). It generally occurs below an A horizon but

may be at the mineral soil surface. Under the albic horizon there

generally is an argillic, cambic, kandic, natric, or spodic

horizon or a fragipan (defined below). The albic horizon may

lie between a spodic horizon and either a fragipan or an argillic

horizon, or it may be between an argillic or kandic horizon and

a fragipan. It may lie between a mollic epipedon and an argillic

or natric horizon or between a cambic horizon and an argillic,

kandic, or natric horizon or a fragipan. The albic horizon may

separate horizons that, if they were together, would meet the

requirements for a mollic epipedon. It may separate lamellae

that together meet the requirements for an argillic horizon.
10 Keys to Soil Taxonomy

These lamellae are not considered to be part of the albic

horizon.

Argillic Horizon

An argillic horizon is normally a subsurface horizon with a

significantly higher percentage of phyllosilicate clay than the

overlying soil material. It shows evidence of clay illuviation.

The argillic horizon forms below the soil surface, but it may be

exposed at the surface later by erosion.

Required Characteristics

1. All argillic horizons must meet both of the following

requirements:

a. One of the following:

(1) If the argillic horizon is coarse-loamy, fine-loamy,

coarse-silty, fine-silty, fine, or very-fine or is loamy or

clayey, including skeletal counterparts, it must be at least

7.5 cm thick or at least one-tenth as thick as the sum of

the thickness of all overlying horizons, whichever is

greater; or

(2) If the argillic horizon is sandy or sandy-skeletal, it

must be at least 15 cm thick; or

(3) If the argillic horizon is composed entirely of

lamellae, the combined thickness of the lamellae that are

0.5 cm or more thick must be 15 cm or more; and

b. Evidence of clay illuviation in at least one of the

following forms:

(1) Oriented clay bridging the sand grains; or

(2) Clay films lining pores; or

(3) Clay films on both vertical and horizontal surfaces

of peds; or

(4) Thin sections with oriented clay bodies that are

more than 1 percent of the section; or

(5) If the coefficient of linear extensibility is 0.04 or

higher and the soil has distinct wet and dry seasons, then

the ratio of fine clay to total clay in the illuvial horizon is

greater by 1.2 times or more than the ratio in the eluvial

horizon; and

2. If an eluvial horizon remains and there is no lithologic

discontinuity between it and the illuvial horizon and no plow

layer directly above the illuvial layer, then the illuvial horizon

must contain more total clay than the eluvial horizon within a

vertical distance of 30 cm or less, as follows:

a. If any part of the eluvial horizon has less than 15 percent

total clay in the fine-earth fraction, the argillic horizon must

contain at least 3 percent (absolute) more clay (10 percent

versus 13 percent, for example); or

b. If the eluvial horizon has 15 to 40 percent total clay in

the fine-earth fraction, the argillic horizon must have at least

1.2 times more clay than the eluvial horizon; or

c. If the eluvial horizon has 40 percent or more total clay in

the fine-earth fraction, the argillic horizon must contain at

least 8 percent (absolute) more clay (42 percent versus 50

percent, for example).

Calcic Horizon

The calcic horizon is an illuvial horizon in which secondary

calcium carbonate or other carbonates have accumulated to a

significant extent.

Required Characteristics

The calcic horizon:

1. Is 15 cm or more thick; and

2. Has one or more of the following:

a. 15 percent or more (by weight) CaCO3 equivalent (see

below), and its CaCO3 equivalent is 5 percent or more

(absolute) higher than that of an underlying horizon; or

b. 15 percent or more (by weight) CaCO3 equivalent and 5

percent or more (by volume) identifiable secondary

carbonates; or

c. 5 percent or more (by weight) calcium carbonate

equivalent and has:

(1) Less than 18 percent clay in the fine-earth fraction;

and

(2) A sandy, sandy-skeletal, coarse-loamy, or loamyskeletal particle-size class; and

(3) 5 percent or more (by volume) identifiable

secondary carbonates or a calcium carbonate equivalent

(by weight) that is 5 percent or more (absolute) higher

than that of an underlying horizon; and

3. Is not cemented or indurated in any part by carbonates,

with or without other cementing agents, or is cemented in some

part and the cemented part satisfies one of the following:

a. It is characterized by so much lateral discontinuity that

roots can penetrate through noncemented zones or along

vertical fractures with a horizontal spacing of less than 10

cm; or

b. The cemented layer is less than 1 cm thick and consists

of a laminar cap underlain by a lithic or paralithic contact; or
Horizons and Characteristics Diagnostic for the Higher Categories 11

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c. The cemented layer is less than 10 cm thick.

Cambic Horizon

A cambic horizon is the result of physical alterations,

chemical transformations, or removals or of a combination of

two or more of these processes.

Required Characteristics

The cambic horizon is an altered horizon 15 cm or more

thick. If it is composed of lamellae, the combined thickness of

the lamellae must be 15 cm or more. In addition, the cambic

horizon must meet all of the following:

1. Has a texture of very fine sand, loamy very fine sand, or

finer; and

2. Shows evidence of alteration in one of the following

forms:

a. Aquic conditions within 50 cm of the soil surface or

artificial drainage and all of the following:

(1) Soil structure or the absence of rock structure in

more than one-half of the volume; and

(2) Colors that do not change on exposure to air;

and

(3) Dominant color, moist, on faces of peds or in the

matrix as follows:

(a) Value of 3 or less and chroma of 0; or

(b) Value of 4 or more and chroma of 1 or less; or

(c) Any value, chroma of 2 or less, and redox

concentrations; or

b. Does not have the combination of aquic conditions

within 50 cm of the soil surface or artificial drainage and

colors, moist, as defined in item 2-a-(3) above, and has soil

structure or the absence of rock structure in more than onehalf of the volume and one or more of the following

properties:

(1) Higher chroma, higher value, redder hue, or higher

clay content than the underlying horizon or an overlying

horizon; or

(2) Evidence of the removal of carbonates or gypsum;

and

3. Has properties that do not meet the requirements for an

anthropic, histic, folistic, melanic, mollic, plaggen, or umbric

epipedon, a duripan or fragipan, or an argillic, calcic, gypsic,

natric, oxic, petrocalcic, petrogypsic, placic, or spodic horizon;

and

4. Is not part of an Ap horizon and does not have a brittle

manner of failure in more than 60 percent of the matrix.

Duripan

Required Characteristics

A duripan is a silica-cemented subsurface horizon with or

without auxiliary cementing agents. It can occur in conjunction

with a petrocalcic horizon.

A duripan must meet all of the following requirements:

1. The pan is cemented or indurated in more than 50 percent

of the volume of some horizon; and

2. The pan shows evidence of the accumulation of opal or

other forms of silica, such as laminar caps, coatings, lenses,

partly filled interstices, bridges between sand-sized grains, or

coatings on rock and pararock fragments; and

3. Less than 50 percent of the volume of air-dry fragments

slakes in 1N HCl even during prolonged soaking, but more than

50 percent slakes in concentrated KOH or NaOH or in

alternating acid and alkali; and

4. Because of lateral continuity, roots can penetrate the pan

only along vertical fractures with a horizontal spacing of 10 cm

or more.

Fragipan

Required Characteristics

To be identified as a fragipan, a layer must have all of the

following characteristics:

1. The layer is 15 cm or more thick; and

2. The layer shows evidence of pedogenesis within the

horizon or, at a minimum, on the faces of structural units;

and

3. The layer has very coarse prismatic, columnar, or blocky

structure of any grade, has weak structure of any size, or is

massive. Separations between structural units that allow roots to

enter have an average spacing of 10 cm or more on the

horizontal dimensions; and

4. Air-dry fragments of the natural soil fabric, 5 to 10 cm in

diameter, from more than 50 percent of the layer slake when

they are submerged in water; and

5. The layer has, in 60 percent or more of the volume, a firm

or firmer rupture-resistance class, a brittle manner of failure at

or near field capacity, and virtually no roots; and

6. The layer is not effervescent (in dilute HCl).

Glossic Horizon

The glossic horizon (Gr. glossa, tongue) develops as a result

of the degradation of an argillic, kandic, or natric horizon from

which clay and free iron oxides are removed.
12 Keys to Soil Taxonomy

Required Characteristics

The glossic horizon is 5 cm or more thick and consists of:

1. An eluvial part, i.e., albic materials (defined below), which

constitute 15 to 85 percent (by volume) of the glossic horizon;

and

2. An illuvial part, i.e., remnants (pieces) of an argillic,

kandic, or natric horizon (defined below).

Gypsic Horizon

The gypsic horizon is an illuvial horizon in which secondary

gypsum has accumulated to a significant extent.

Required Characteristics

A gypsic horizon has all of the following properties:

1. Is 15 cm or more thick; and

2. Is not cemented or indurated by gypsum, with or without

other cementing agents; is cemented and the cemented parts

are less than 10 cm thick; or, because of lateral discontinuity,

roots can penetrate along vertical fractures with a horizontal

spacing of less than 10 cm; and

3. Is 5 percent or more (by weight) gypsum and 1 percent or

more (by volume) secondary visible gypsum; and

4. Has a product of thickness, in cm, multiplied by the

gypsum content (percent by weight) of 150 or more. Thus, a

horizon 30 cm thick that is 5 percent gypsum qualifies as a

gypsic horizon if it is 1 percent or more (by volume) visible

gypsum and any cementation is as described in 2 above. The

gypsum content (percent by weight) is calculated as the product

of gypsum content, expressed as cmolc

 kg-1 soil (of the fineearth fraction), and the equivalent weight of gypsum (86)

expressed as a percentage.

Kandic Horizon

Required Characteristics

The kandic horizon:

1. Is a vertically continuous subsurface horizon that underlies

a coarser textured surface horizon. The minimum thickness of

the surface horizon is 18 cm after mixing or 5 cm if the textural

transition to the kandic horizon is abrupt and there is no densic,

lithic, paralithic, or petroferric contact (defined below) within

50 cm of the mineral soil surface; and

2. Has its upper boundary:

a. At the point where the clay percentage in the fine-earth

fraction, increasing with depth within a vertical distance of

15 cm or less, is either:

(1) 4 percent or more (absolute) higher than that in the

surface horizon if that horizon has less than 20 percent

total clay in the fine-earth fraction; or

(2) 20 percent or more (relative) higher than that in the

surface horizon if that horizon has 20 to 40 percent total

clay in the fine-earth fraction; or

(3) 8 percent or more (absolute) higher than that in the

surface horizon if that horizon has more than 40 percent

total clay in the fine-earth fraction; and

b. At a depth:

(1) Between 100 cm and 200 cm from the mineral soil

surface if the particle-size class is sandy or sandy-skeletal

throughout the upper 100 cm; or

(2) Within 100 cm from the mineral soil surface if the

clay content in the fine-earth fraction of the surface

horizon is 20 percent or more; or

(3) Within 125 cm from the mineral soil surface for all

other soils; and

3. Has a thickness of either:

a. 30 cm or more; or

b. 15 cm or more if there is a densic, lithic, paralithic, or

petroferric contact within 50 cm of the mineral soil surface

and the kandic horizon constitutes 60 percent or more of the

vertical distance between a depth of 18 cm and the contact; and

4. Has a texture of loamy very fine sand or finer; and

5. Has an apparent CEC of 16 cmol(+) or less per kg clay (by

1N NH4

OAc pH 7) and an apparent ECEC of 12 cmol(+) or less

per kg clay (sum of bases extracted with 1N NH4OAc pH 7 plus

1N KCl-extractable Al) in 50 percent or more of its thickness

between the point where the clay increase requirements are met

and either a depth of 100 cm below that point or a densic, lithic,

paralithic, or petroferric contact if shallower. (The percentage of

clay is either measured by the pipette method or estimated to be

2.5 times [percent water retained at 1500 kPa tension minus

percent organic carbon], whichever is higher, but no more than

100); and

6. Has a regular decrease in organic-carbon content with

increasing depth, no fine stratification, and no overlying layers

more than 30 cm thick that have fine stratification and/or an

organic-carbon content that decreases irregularly with

increasing depth.

Natric Horizon

Required Characteristics

The natric horizon has, in addition to the properties of the

argillic horizon:

1. Either:
Horizons and Characteristics Diagnostic for the Higher Categories 13

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a. Columns or prisms in some part (generally the upper

part), which may break to blocks; or

b. Both blocky structure and eluvial materials, which

contain uncoated silt or sand grains and extend more than

2.5 cm into the horizon; and

2. Either:

a. An exchangeable sodium percentage (ESP) of 15

percent or more (or a sodium adsorption ratio [SAR] of 13 or

more) in one or more horizons within 40 cm of its upper

boundary; or

b. More exchangeable magnesium plus sodium than

calcium plus exchange acidity (at pH 8.2) in one or more

horizons within 40 cm of its upper boundary if the ESP is 15

or more (or the SAR is 13 or more) in one or more horizons

within 200 cm of the mineral soil surface.

Ortstein

Required Characteristics

Ortstein has all of the following:

1. Consists of spodic materials; and

2. Is in a layer that is 50 percent or more cemented; and

3. Is 25 mm or more thick.

Oxic Horizon

Required Characteristics

The oxic horizon is a subsurface horizon that does not have

andic soil properties (defined below) and has all of the

following characteristics:

1. A thickness of 30 cm or more; and

2. A texture of sandy loam or finer in the fine-earth fraction;

and

3. Less than 10 percent weatherable minerals in the 50-

to 200-micron fraction; and

4. Rock structure in less than 5 percent of its volume, unless

the lithorelicts with weatherable minerals are coated with

sesquioxides; and

5. A diffuse upper boundary, i.e., within a vertical distance

of 15 cm, a clay increase with increasing depth of:

a. Less than 4 percent (absolute) in its fine-earth fraction if

the fine-earth fraction of the surface horizon contains less

than 20 percent clay; or

b. Less than 20 percent (relative) in its fine-earth fraction if

the fine-earth fraction of the surface horizon contains 20 to

40 percent clay; or

c. Less than 8 percent (absolute) in its fine-earth fraction if

the fine-earth fraction of the surface horizon contains 40

percent or more clay); and

6. An apparent CEC of 16 cmol(+) or less per kg clay (by 1N

NH4

OAc pH 7) and an apparent ECEC of 12 cmol(+) or less per

kg clay (sum of bases extracted with 1N NH4OAc pH 7 plus 1N

KCl-extractable Al). (The percentage of clay is either measured

by the pipette method or estimated to be 3 times [percent water

retained at 1500 kPa tension minus percent organic carbon],

whichever value is higher, but no more than 100).

Petrocalcic Horizon

The petrocalcic horizon is an illuvial horizon in which

secondary calcium carbonate or other carbonates have

accumulated to the extent that the horizon is cemented or

indurated.

Required Characteristics

A petrocalcic horizon must meet the following

requirements:

1. The horizon is cemented or indurated by carbonates, with

or without silica or other cementing agents; and

2. Because of lateral continuity, roots can penetrate only along

vertical fractures with a horizontal spacing of 10 cm or more;

and

3. The horizon has a thickness of:

a. 10 cm or more; or

b. 1 cm or more if it consists of a laminar cap directly

underlain by bedrock.

Petrogypsic Horizon

The petrogypsic horizon is an illuvial horizon, 10 cm or

more thick, in which secondary gypsum has accumulated to the

extent that the horizon is cemented or indurated.

Required Characteristics

A petrogypsic horizon must meet the following

requirements:

1. The horizon is cemented or indurated by gypsum, with or

without other cementing agents; and

2. Because of lateral continuity, roots can penetrate only along

vertical fractures with a horizontal spacing of 10 cm or more; and

3. The horizon is 10 cm or more thick; and

4. The horizon is 5 percent or more gypsum, and the product

of its thickness, in cm, multiplied by the gypsum content

percentage is 150 or more.
14 Keys to Soil Taxonomy

Placic Horizon

The placic horizon (Gr. base of plax, flat stone; meaning a

thin cemented pan) is a thin, black to dark reddish pan that is

cemented by iron (or iron and manganese) and organic matter.

Required Characteristics

A placic horizon must meet the following requirements:

1. The horizon is cemented or indurated with iron or iron and

manganese and organic matter, with or without other cementing

agents; and

2. Because of lateral continuity, roots can penetrate only along

vertical fractures with a horizontal spacing of 10 cm or more;

and

3. The horizon has a minimum thickness of 1 mm and, where

associated with spodic materials, is less than 25 mm thick.

Salic Horizon

A salic horizon is a horizon of accumulation of salts that are

more soluble than gypsum in cold water.

Required Characteristics

A salic horizon is 15 cm or more thick and has, for 90

consecutive days or more in normal years:

1. An electrical conductivity (EC) equal to or greater than 30

dS/m in the water extracted from a saturated paste; and

2. A product of the EC, in dS/m, and thickness, in cm,

equal to 900 or more.

Sombric Horizon

A sombric horizon (F. sombre, dark) is a subsurface horizon

in mineral soils that has formed under free drainage. It contains

illuvial humus that is neither associated with aluminum, as is

the humus in the spodic horizon, nor dispersed by sodium, as is

common in the natric horizon. Consequently, the sombric

horizon does not have the high cation-exchange capacity in its

clay that characterizes a spodic horizon and does not have the

high base saturation of a natric horizon. It does not underlie an

albic horizon.

Sombric horizons are thought to be restricted to the cool,

moist soils of high plateaus and mountains in tropical or

subtropical regions. Because of strong leaching, their base

saturation is low (less than 50 percent by NH4

OAc).

The sombric horizon has a lower color value or chroma, or

both, than the overlying horizon and commonly contains more

organic matter. It may have formed in an argillic, cambic, or

oxic horizon. If peds are present, the dark colors are most

pronounced on surfaces of peds.

In the field a sombric horizon is easily mistaken for a

buried A horizon. It can be distinguished from some buried

epipedons by lateral tracing. In thin sections the organic

matter of a sombric horizon appears more concentrated on

peds and in pores than uniformly dispersed throughout the

matrix.

Spodic Horizon

A spodic horizon is an illuvial layer with 85 percent or more

spodic materials (defined below).

Required Characteristics

A spodic horizon is normally a subsurface horizon

underlying an O, A, Ap, or E horizon. It may, however, meet the

definition of an umbric epipedon.

A spodic horizon must have 85 percent or more spodic

materials in a layer 2.5 cm or more thick that is not part of any

Ap horizon.

Other Diagnostic Soil Characteristics

(Mineral Soils)

Diagnostic soil characteristics are features of the soil that are

used in various places in the keys or in definitions of diagnostic

horizons.

Abrupt Textural Change

An abrupt textural change is a specific kind of change that

may occur between an ochric epipedon or an albic horizon and

an argillic horizon. It is characterized by a considerable increase

in clay content within a very short vertical distance in the zone

of contact. If the clay content in the fine-earth fraction of the

ochric epipedon or albic horizon is less than 20 percent, it

doubles within a vertical distance of 7.5 cm or less. If the clay

content in the fine-earth fraction of the ochric epipedon or the

albic horizon is 20 percent or more, there is an increase of 20

percent or more (absolute) within a vertical distance of 7.5 cm

or less (e.g., an increase from 22 to 42 percent) and the clay

content in some part of the argillic horizon is 2 times or more

the amount contained in the overlying horizon.

Normally, there is no transitional horizon between an ochric

epipedon or an albic horizon and an argillic horizon, or the

transitional horizon is too thin to be sampled. Some soils,

however, have a glossic horizon or interfingering of albic

materials (defined below) in parts of the argillic horizon. The

upper boundary of such a horizon is irregular or even

discontinuous. Sampling this mixture as a single horizon might

create the impression of a relatively thick transitional horizon,

whereas the thickness of the actual transition at the contact may

be no more than 1 mm.
Horizons and Characteristics Diagnostic for the Higher Categories 15

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Albic Materials

Albic (L. albus, white) materials are soil materials with a

color that is largely determined by the color of primary sand

and silt particles rather than by the color of their coatings. This

definition implies that clay and/or free iron oxides have been

removed from the materials or that the oxides have been

segregated to such an extent that the color of the materials is

largely determined by the color of the primary particles.

Required Characteristics

Albic materials have one of the following colors:

1. Chroma of 2 or less; and either

a. A color value, moist, of 3 and a color value, dry, of 6 or

more; or

b. A color value, moist, of 4 or more and a color value, dry,

of 5 or more; or

2. Chroma of 3 or less; and either

a. A color value, moist, of 6 or more; or

b. A color value, dry, of 7 or more; or

3. Chroma that is controlled by the color of uncoated grains of

silt or sand, hue of 5YR or redder, and the color values listed in

item 1-a or 1-b above.

Relatively unaltered layers of light colored sand, volcanic

ash, or other materials deposited by wind or water are not

considered albic materials, although they may have the same

color and apparent morphology. These deposits are parent

materials that are not characterized by the removal of clay

and/or free iron and do not overlie an illuvial horizon or other

soil horizon, except for a buried soil. Light colored krotovinas

or filled root channels should be considered albic materials only

if they have no fine stratifications or lamellae, if any sealing

along the krotovina walls has been destroyed, and if these

intrusions have been leached of free iron oxides and/or clay

after deposition.

Andic Soil Properties

Andic soil properties commonly form during weathering of

tephra or other parent materials containing a significant content

of volcanic glass. Soils that are in cool, humid climates and

have abundant organic carbon, however, may develop andic soil

properties without the influence of volcanic glass. A suite of

glass and glass-coated minerals rich in silica is termed volcanic

glass in this taxonomy. These minerals are relatively soluble

and undergo fairly rapid transformation when the soils are

moist. Andic soil properties represent a stage in transition where

weathering and transformation of primary alumino-silicates

(e.g., volcanic glass) have proceeded only to the point of the

formation of short-range-order materials, such as allophane,

imogolite, and ferrihydrite, or of metal-humus complexes. The

concept of andic soil properties includes moderately weathered

soil material, rich in short-range-order materials or metalhumus complexes, or both, with or without volcanic glass

(required characteristic 2) and weakly weathered soil, less rich

in short-range-order materials with volcanic glass (required

characteristic 3).

Relative amounts of allophane, imogolite, ferrihydrite, or

metal-humus complexes in the colloidal fraction are inferred

from laboratory analyses of aluminum, iron, and silica extracted

by ammonium oxalate, and from phosphate retention. Soil

scientists may use smeariness or pH in 1N sodium fluoride

(NaF) as field indicators of andic soil properties. Volcanic glass

content is the percent volcanic glass (by grain count) in the

coarse silt and sand (0.02 to 2.0 mm) fraction. Most soil

materials with andic soil properties consist of mineral soil

materials, but some are organic soil materials with less than 25

percent organic carbon.

Required Characteristics

Soil materials with andic soil properties must have a fineearth fraction that meets the following requirements:

1. Less than 25 percent organic carbon (by weight) and one or

both of the following:

2. All of the following:

a. Bulk density, measured at 33 kPa water retention, of

0.90 g/cm3 or less; and

b. Phosphate retention of 85 percent or more; and

c. Al + 1⁄2 Fe content (by ammonium oxalate) equal to 2.0

percent or more; or

3. All of the following:

a. 30 percent or more of the fine-earth fraction is 0.02 to

2.0 mm in size; and

b. Phosphate retention of 25 percent or more; and

c. Al + 1⁄2 Fe content (by ammonium oxalate) equal to 0.4

percent or more; and

d. Volcanic glass content of 5 percent or more; and

e. [(Al + 1⁄2 Fe content, percent) times (15.625)] +

[volcanic glass content, percent] = 36.25 or more.

The shaded area in figure 1 illustrates criteria 3c, 3d, and 3e.

Anhydrous Conditions

Anhydrous conditions (Gr. anydros, waterless) refer to the

moisture condition of soils in very cold deserts and other areas

with permafrost (often dry permafrost). These soils typically
16 Keys to Soil Taxonomy

have low precipitation (usually less than 50 mm water

equivalent per year) and a moisture content of less than 3

percent by weight. Anhydrous soil conditions are similar to the

aridic (torric) soil moisture regimes (defined below), except that

the soil temperature at 50 cm is less than 5 oC throughout the

year in the soil layers with these conditions.

Required Characteristics

Soils with anhydrous conditions have a mean annual soil

temperature of 0 o

C or colder. The layer from 10 to 70 cm

below the soil surface has a soil temperature of less than 5 o C

throughout the year and this layer:

1. Includes no ice-cemented permafrost; and

2. Is dry (water held at 1500 kPa or more) in one-half or more

of the soil for one-half or more of the time the layer has a soil

temperature above 0 oC; or

3. Has a rupture-resistance class of loose to slightly hard

throughout when the soil temperature is 0 oC or colder, except

where a cemented pedogenic horizon occurs.

Coefficient of Linear Extensibility (COLE)

The coefficient of linear extensibility (COLE) is the ratio of

the difference between the moist length and dry length of a clod

to its dry length. It is (Lm - Ld)/Ld, where Lm is the length at

33 kPa tension and Ld is the length when dry. COLE can be

calculated from the differences in bulk density of the clod when

moist and when dry. An estimate of COLE can be calculated in

the field by measuring the distance between two pins in a clod

of undisturbed soil at field capacity and again after the clod has

dried. COLE does not apply if the shrinkage is irreversible.

Durinodes

Durinodes (L. durus, hard, and nodus, knot) are weakly

cemented to indurated nodules with a diameter of 1 cm or more.

The cement is SiO2, presumably opal and microcrystalline

forms of silica. Durinodes break down in hot concentrated KOH

after treatment with HCl to remove carbonates but do not break

down with concentrated HCl alone. Dry durinodes do not slake

appreciably in water, but prolonged soaking can result in

spalling of very thin platelets. Durinodes are firm or firmer and

brittle when wet, both before and after treatment with acid.

Most durinodes are roughly concentric when viewed in cross

section, and concentric stringers of opal are visible under a

hand lens.

Fragic Soil Properties

Fragic soil properties are the essential properties of a

fragipan. They have neither the layer thickness nor volume

requirements for the fragipan. Fragic soil properties are in

subsurface horizons, although they can be at or near the surface

in truncated soils. Aggregates with fragic soil properties have a

firm or firmer rupture-resistance class and a brittle manner of

failure when soil water is at or near field capacity. Air-dry

fragments of the natural fabric, 5 to 10 cm in diameter, slake

when they are submerged in water. Aggregates with fragic soil

properties show evidence of pedogenesis, including one or

more of the following: oriented clay within the matrix or on

faces of peds, redoximorphic features within the matrix or on

faces of peds, strong or moderate soil structure, and coatings of

albic materials or uncoated silt and sand grains on faces of peds

or in seams. Peds with these properties are considered to have

fragic soil properties regardless of whether or not the density

and brittleness are pedogenic.

Soil aggregates with fragic soil properties must:

1. Show evidence of pedogenesis within the aggregates or, at

a minimum, on the faces of the aggregates; and

2. Slake when air-dry fragments of the natural fabric, 5 to 10

cm in diameter, are submerged in water; and

3. Have a firm or firmer rupture-resistance class and a brittle

manner of failure when soil water is at or near field capacity; and

Figure 1.—Soils that are plotted in the shaded area meet the andic soil

properties criteria c, d, and e under item 3 of the required

characteristics. To qualify as soils with andic properties, the soils must

also meet the listed requirements for organic-carbon content,

phosphate retention, and particle-size distribution.
Horizons and Characteristics Diagnostic for the Higher Categories 17

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4. Restrict the entry of roots into the matrix when soil water is

at or near field capacity.

Identifiable Secondary Carbonates

The term “identifiable secondary carbonates” is used in the

definitions of a number of taxa. It refers to translocated

authigenic calcium carbonate that has been precipitated in place

from the soil solution rather than inherited from a soil parent

material, such as a calcareous loess or till.

Identifiable secondary carbonates either may disrupt the soil

structure or fabric, forming masses, nodules, concretions, or

spheroidal aggregates (white eyes) that are soft and powdery

when dry, or may be present as coatings in pores, on structural

faces, or on the undersides of rock or pararock fragments. If

present as coatings, the secondary carbonates cover a significant

part of the surfaces. Commonly, they coat all of the surfaces to

a thickness of 1 mm or more. If little calcium carbonate is

present in the soil, however, the surfaces may be only partially

coated. The coatings must be thick enough to be visible when

moist. Some horizons are entirely engulfed by carbonates. The

color of these horizons is largely determined by the carbonates.

The carbonates in these horizons are within the concept of

identifiable secondary carbonates.

The filaments commonly seen in a dry calcareous horizon

are within the meaning of identifiable secondary carbonates if

the filaments are thick enough to be visible when the soil is

moist. Filaments commonly branch on structural faces.

Interfingering of Albic Materials

The term “interfingering of albic materials” refers to albic

materials that penetrate 5 cm or more into an underlying

argillic, kandic, or natric horizon along vertical and, to a lesser

degree, horizontal faces of peds. There need not be a continuous

overlying albic horizon. The albic materials constitute less than

15 percent of the layer that they penetrate, but they form

continuous skeletans (ped coatings of clean silt or sand defined

by Brewer, 1976) 1 mm or more thick on the vertical faces of

peds, which means a total width of 2 mm or more between

abutting peds. Because quartz is such a common constituent of

silt and sand, these skeletans are usually light gray when moist

and nearly white when dry, but their color is determined in large

part by the color of the sand or silt fraction.

Required Characteristics

Interfingering of albic materials is recognized if albic

materials:

1. Penetrate 5 cm or more into an underlying argillic or natric

horizon; and

2. Are 2 mm or more thick between vertical faces of abutting

peds; and

3. Constitute less than 15 percent (by volume) of the layer

that they penetrate.

Lamellae

A lamella is an illuvial horizon less than 7.5 cm thick. Each

lamella contains an accumulation of oriented silicate clay on or

bridging sand and silt grains (and rock fragments if any are

present). A lamella has more silicate clay than the overlying

eluvial horizon.

Required Characteristics

A lamella is an illuvial horizon less than 7.5 cm thick formed

in unconsolidated regolith more than 50 cm thick. Each lamella

contains an accumulation of oriented silicate clay on or

bridging the sand and silt grains (and coarse fragments if any

are present). Each lamella is required to have more silicate clay

than the overlying eluvial horizon.

Lamellae occur in a vertical series of two or more, and each

lamella must have an overlying eluvial horizon. (An eluvial

horizon is not required above the uppermost lamella if the soil

is truncated.)

Lamellae may meet the requirements for either a cambic

or an argillic horizon. A combination of two or more lamellae

15 cm or more thick is a cambic horizon if the texture is very

fine sand, loamy very fine sand, or finer. A combination of

two or more lamellae meets the requirements for an argillic

horizon if there is 15 cm or more cumulative thickness of

lamellae that are 0.5 cm or more thick and that have a clay

content of either:

1. 3 percent or more (absolute) higher than in the overlying

eluvial horizon (e.g., 13 percent versus 10 percent) if any part

of the eluvial horizon has less than 15 percent clay in the fineearth fraction; or

2. 20 percent or more (relative) higher than in the overlying

eluvial horizon (e.g., 24 percent versus 20 percent) if all parts of

the eluvial horizon have more than 15 percent clay in the fineearth fraction.

Linear Extensibility (LE)

Linear extensibility (LE) helps to predict the potential of a

soil to shrink and swell. The LE of a soil layer is the product of

the thickness, in cm, multiplied by the COLE of the layer in

question. The LE of a soil is the sum of these products for all

soil horizons.

Lithologic Discontinuities

Lithologic discontinuities are significant changes in particlesize distribution or mineralogy that represent differences in

lithology within a soil. A lithologic discontinuity can also
18 Keys to Soil Taxonomy

denote an age difference. For information on using horizon

designations for lithologic discontinuities, see the Soil Survey

Manual (USDA, SCS, 1993).

Not everyone agrees on the degree of change required for a

lithologic discontinuity. No attempt is made to quantify

lithologic discontinuities. The discussion below is meant to

serve as a guideline.

Several lines of field evidence can be used to evaluate

lithologic discontinuities. In addition to mineralogical and

textural differences that may require laboratory studies, certain

observations can be made in the field. These include but are not

limited to the following:

1. Abrupt textural contacts.—An abrupt change in

particle-size distribution, which is not solely a change in clay

content resulting from pedogenesis, can often be observed.

2. Contrasting sand sizes.—Significant changes in sand

size can be detected. For example, if material containing mostly

medium sand or finer sand abruptly overlies material containing

mostly coarse sand and very coarse sand, one can assume that

there are two different materials. Although the materials may be

of the same mineralogy, the contrasting sand sizes result from

differences in energy at the time of deposition by water and/or

wind.

3. Bedrock lithology vs. rock fragment lithology in the

soil.—If a soil with rock fragments overlies a lithic contact, one

would expect the rock fragments to have a lithology similar to

that of the material below the lithic contact. If many of the rock

fragments do not have the same lithology as the underlying

bedrock, the soil is not derived completely from the underlying

bedrock.

4. Stone lines.—The occurrence of a horizontal line of

rock fragments in the vertical sequence of a soil indicates that

the soil may have developed in more than one kind of parent

material. The material above the stone line is most likely

transported, and the material below may be of different origin.

5. Inverse distribution of rock fragments.—A lithologic

discontinuity is often indicated by an erratic distribution of rock

fragments. The percentage of rock fragments decreases with

increasing depth. This line of evidence is useful in areas of soils

that have relatively unweathered rock fragments.

6. Rock fragment weathering rinds.—Horizons

containing rock fragments with no rinds that overlie horizons

containing rocks with rinds suggest that the upper material is in

part depositional and not related to the lower part in time and

perhaps in lithology.

7. Shape of rock fragments.—A soil with horizons

containing angular rock fragments overlying horizons

containing well rounded rock fragments may indicate a

discontinuity. This line of evidence represents different

mechanisms of transport (colluvial vs. alluvial) or even

different transport distances.

8. Soil color.—Abrupt changes in color that are not the

result of pedogenic processes can be used as indicators of

discontinuity.

9. Micromorphological features.—Marked differences in

the size and shape of resistant minerals in one horizon and not

in another are indicators of differences in materials.

Use of Laboratory Data

Discontinuities are not always readily apparent in the field.

In these cases laboratory data are necessary. Even with

laboratory data, detecting discontinuities may be difficult. The

decision is a qualitative or perhaps a partly quantitative

judgment. General concepts of lithology as a function of depth

might include:

1. Laboratory data—visual scan.—The array of

laboratory data is assessed in an attempt to determine if a fielddesignated discontinuity is corroborated and if any data show

evidence of a discontinuity not observed in the field. One must

sort changes in lithology from changes caused by pedogenic

processes. In most cases the quantities of sand and coarser

fractions are not altered significantly by soil-forming processes.

Therefore, an abrupt change in sand size or sand mineralogy is

a clue to lithologic change. Gross soil mineralogy and the

resistant mineral suite are other clues.

2. Data on a clay-free basis.—A common manipulation in

assessing lithologic change is computation of sand and silt

separates on a carbonate-free, clay-free basis (percent fraction,

e.g., fine sand and very fine sand, divided by percent sand plus

silt, times 100). Clay distribution is subject to pedogenic change

and may either mask inherited lithologic differences or produce

differences that are not inherited from lithology. The numerical

array computed on a clay-free basis can be inspected visually or

plotted as a function of depth.

Another aid used to assess lithologic changes is computation

of the ratios of one sand separate to another. The ratios can be

computed and examined as a numerical array, or they can be

plotted. The ratios work well if sufficient quantities of the two

fractions are available. Low quantities magnify changes in

ratios, especially if the denominator is low.

n Value

The n value (Pons and Zonneveld, 1965) characterizes the

relation between the percentage of water in a soil under field

conditions and its percentages of inorganic clay and humus. The

n value is helpful in predicting whether a soil can be grazed by

livestock or can support other loads and in predicting what

degree of subsidence would occur after drainage.

For mineral soil materials that are not thixotropic, the n value

can be calculated by the following formula:

n = (A - 0.2R)/(L + 3H)

In this formula, A is the percentage of water in the soil in

field condition, calculated on a dry-soil basis; R is the

percentage of silt plus sand; L is the percentage of clay; and H

is the percentage of organic matter (percent organic carbon

multiplied by 1.724).
Horizons and Characteristics Diagnostic for the Higher Categories 19

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Few data for calculations of the n value are available in the

United States, but the critical n value of 0.7 can be

approximated closely in the field by a simple test of squeezing a

soil sample in the hand. If the soil flows between the fingers

with difficulty, the n value is between 0.7 and 1.0 (slightly fluid

manner of failure class); if the soil flows easily between the

fingers, the n value is 1 or more (moderately fluid or very fluid

manner of failure class).

Petroferric Contact

A petroferric (Gr. petra, rock, and L. ferrum, iron; implying

ironstone) contact is a boundary between soil and a continuous

layer of indurated material in which iron is an important cement

and organic matter is either absent or present only in traces. The

indurated layer must be continuous within the limits of each

pedon, but it may be fractured if the average lateral distance

between fractures is 10 cm or more. The fact that this ironstone

layer contains little or no organic matter distinguishes it from a

placic horizon and an indurated spodic horizon (ortstein), both

of which contain organic matter.

Several features can aid in making the distinction between a

lithic contact and a petroferric contact. First, a petroferric

contact is roughly horizontal. Second, the material directly

below a petroferric contact contains a high amount of iron

(normally 30 percent or more Fe2O3). Third, the ironstone

sheets below a petroferric contact are thin; their thickness

ranges from a few centimeters to very few meters. Sandstone,

on the other hand, may be thin or very thick, may be levelbedded or tilted, and may contain only a small percentage of

Fe2O3. In the Tropics, the ironstone is generally more or less

vesicular.

Plinthite

Plinthite (Gr. plinthos, brick) is an iron-rich, humus-poor

mixture of clay with quartz and other minerals. It commonly

occurs as dark red redox concentrations that usually form platy,

polygonal, or reticulate patterns. Plinthite changes irreversibly

to an ironstone hardpan or to irregular aggregates on exposure

to repeated wetting and drying, especially if it is also exposed to

heat from the sun. The lower boundary of a zone in which

plinthite occurs generally is diffuse or gradual, but it may be

abrupt at a lithologic discontinuity.

Generally, plinthite forms in a horizon that is saturated with

water for some time during the year. Initially, iron is normally

segregated in the form of soft, more or less clayey, red or dark

red redox concentrations. These concentrations are not

considered plinthite unless there has been enough segregation

of iron to permit their irreversible hardening on exposure to

repeated wetting and drying. Plinthite is firm or very firm when

the soil moisture content is near field capacity and hard when

the moisture content is below the wilting point. Plinthite does

not harden irreversibly as a result of a single cycle of drying

and rewetting. After a single drying, it will remoisten and then

can be dispersed in large part if one shakes it in water with a

dispersing agent.

In a moist soil, plinthite is soft enough to be cut with a

spade. After irreversible hardening, it is no longer considered

plinthite but is called ironstone. Indurated ironstone materials

can be broken or shattered with a spade but cannot be dispersed

if one shakes tham in water with a dispersing agent.

Resistant Minerals

Several references are made to resistant minerals in this

taxonomy. Obviously, the stability of a mineral in the soil is a

partial function of the soil moisture regime. Where resistant

minerals are referred to in the definitions of diagnostic horizons

and of various taxa, a humid climate, past or present, is always

assumed.

Resistant minerals are durable minerals in the 0.02 to 2.0

mm fraction. Examples are quartz, zircon, tourmaline, beryl,

anatase, rutile, iron oxides and oxyhydroxides, 1:1

dioctahedral phyllosilicates (kandites), gibbsite, and hydroxyalluminum interlayered 2:1 minerals (Burt, 2004).

Slickensides

Slickensides are polished and grooved surfaces and generally

have dimensions exceeding 5 cm. They are produced when one

soil mass slides past another. Some slickensides occur at the

lower boundary of a slip surface where a mass of soil moves

downward on a relatively steep slope. Slickensides result

directly from the swelling of clay minerals and shear failure.

They are very common in swelling clays that undergo marked

changes in moisture content.

Spodic Materials

Spodic materials form in an illuvial horizon that normally

underlies a histic, ochric, or umbric epipedon or an albic

horizon. In most undisturbed areas, spodic materials underlie an

albic horizon. They may occur within an umbric epipedon or an

Ap horizon.

A horizon consisting of spodic materials normally has an

optical-density-of-oxalate-extract (ODOE) value of 0.25 or

more, and that value is commonly at least 2 times as high as the

ODOE value in an overlying eluvial horizon. This increase in

ODOE value indicates an accumulation of translocated organic

materials in an illuvial horizon. Soils with spodic materials

show evidence that organic materials and aluminum, with or

without iron, have been moved from an eluvial horizon to an

illuvial horizon.

Definition of Spodic Materials

Spodic materials are mineral soil materials that do not have

all of the properties of an argillic or kandic horizon; are
20 Keys to Soil Taxonomy

dominated by active amorphous materials that are illuvial and

are composed of organic matter and aluminum, with or without

iron; and have both of the following:

1. A pH value in water (1:1) of 5.9 or less and an organiccarbon content of 0.6 percent or more; and

2. One or both of the following:

a. An overlying albic horizon that extends horizontally

through 50 percent or more of each pedon and, directly

under the albic horizon, colors, moist (crushed and smoothed

sample), as follows:

(1) Hue of 5YR or redder; or

(2) Hue of 7.5YR, color value of 5 or less, and chroma

of 4 or less; or

(3) Hue of 10YR or neutral and a color value and

chroma of 2 or less; or

(4) A color of 10YR 3/1; or

b. With or without an albic horizon and one of the colors

listed above or hue of 7.5YR, color value, moist, of 5 or

less, chroma of 5 or 6 (crushed and smoothed sample), and

one or more of the following morphological or chemical

properties:

(1) Cementation by organic matter and aluminum, with

or without iron, in 50 percent or more of each pedon and

a very firm or firmer rupture-resistance class in the

cemented part; or

(2) 10 percent or more cracked coatings on sand grains;

or

(3) Al + 1/2 Fe percentages (by ammonium oxalate)

totaling 0.50 or more, and half that amount or less in an

overlying umbric (or subhorizon of an umbric) epipedon,

ochric epipedon, or albic horizon; or

(4) An optical-density-of-oxalate-extract (ODOE) value

of 0.25 or more, and a value half as high or lower in an

overlying umbric (or subhorizon of an umbric) epipedon,

ochric epipedon, or albic horizon.

Volcanic Glass

Volcanic glass is defined herein as optically isotropic

translucent glass or pumice of any color. It includes glass,

pumice, glass-coated crystalline minerals, glass aggregates, and

glassy materials.

Volcanic glass is typically a dominant component in

relatively unweathered tephra. Weathering and mineral

transformation of volcanic glass can produce short-range-order

minerals, such as allophane, imogolite, and ferrihydrite.

Volcanic glass content is the percent (by grain count) of

glass, glass-coated mineral grains, glass aggregates, and glassy

materials in the 0.02 to 2.0 mm fraction. Typically, the content

is determined for one particle-size fraction (i.e., coarse silt, very

fine sand, or fine sand) and used as an estimate of glass content

in the 0.02 to 2.0 mm fraction.

Volcanic glass content is a criterion in classification of andic

soil properties, subgroups with the formative element "vitr(i),"

and families with "ashy" substitute particle-size classes and the

glassy mineralogy class.

Weatherable Minerals

Several references are made to weatherable minerals in this

taxonomy. Obviously, the stability of a mineral in a soil is a

partial function of the soil moisture regime. Where weatherable

minerals are referred to in the definitions of diagnostic horizons

and of various taxa in this taxonomy, a humid climate, either

present or past, is always assumed. Examples of the minerals

that are included in the meaning of weatherable minerals are all

2:1 phyllosilicates, chlorite, sepiolite, palygorskite, allophane,

1:1 trioctahedral phyllosilicates (serpentines), feldspars,

feldspathoids, ferromagnesian minerals, glass, zeolites,

dolomite, and apatite in the 0.02 to 2.0 mm fraction.

Obviously, this definition of the term “weatherable minerals”

is restrictive. The intent is to include, in the definitions of

diagnostic horizons and various taxa, only

those weatherable minerals that are unstable in a humid climate

compared to other minerals, such as quartz and 1:1 lattice clays,

but that are more resistant to weathering than calcite. Calcite,

carbonate aggregates, gypsum, and halite are not considered

weatherable minerals because they are mobile in the soil. They

appear to be recharged in some otherwise strongly weathered

soils.

Characteristics Diagnostic for

Organic Soils

Following is a description of the characteristics that are used

only with organic soils.

Kinds of Organic Soil Materials

Three different kinds of organic soil materials are

distinguished in this taxonomy, based on the degree of

decomposition of the plant materials from which the organic

materials are derived. The three kinds are (1) fibric, (2) hemic,

and (3) sapric. Because of the importance of fiber content in the

definitions of these materials, fibers are defined before the kinds

of organic soil materials.

Fibers

Fibers are pieces of plant tissue in organic soil materials

(excluding live roots) that:
Horizons and Characteristics Diagnostic for the Higher Categories 21

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1. Are large enough to be retained on a 100-mesh sieve

(openings 0.15 mm across) when the materials are screened;

and

2. Show evidence of the cellular structure of the plants from

which they are derived; and

3. Either are 2 cm or less in their smallest dimension or are

decomposed enough to be crushed and shredded with the

fingers.

Pieces of wood that are larger than 2 cm in cross section

and are so undecomposed that they cannot be crushed and

shredded with the fingers, such as large branches, logs, and

stumps, are not considered fibers but are considered coarse

fragments (comparable to gravel, stones, and boulders in

mineral soils).

Fibric Soil Materials

Fibric soil materials are organic soil materials that either:

1. Contain three-fourths or more (by volume) fibers after

rubbing, excluding coarse fragments; or

2. Contain two-fifths or more (by volume) fibers after

rubbing, excluding coarse fragments, and yield color values and

chromas of 7/1, 7/2, 8/1, 8/2, or 8/3 (fig. 2) on white

chromatographic or filter paper that is inserted into a paste

made of the soil materials in a saturated sodium-pyrophosphate

solution.

Hemic Soil Materials

Hemic soil materials (Gr. hemi, half; implying intermediate

decomposition) are intermediate in their degree of

decomposition between the less decomposed fibric and more

decomposed sapric materials. Their morphological features give

intermediate values for fiber content, bulk density, and water

content. Hemic soil materials are partly altered both physically

and biochemically.

Sapric Soil Materials

Sapric soil materials (Gr. sapros, rotten) are the most highly

decomposed of the three kinds of organic soil materials. They

have the smallest amount of plant fiber, the highest bulk density,

and the lowest water content on a dry-weight basis at saturation.

Sapric soil materials are commonly very dark gray to black.

They are relatively stable; i.e., they change very little physically

and chemically with time in comparison to other organic soil

materials.

Sapric materials have the following characteristics:

1. The fiber content, after rubbing, is less than one-sixth (by

volume), excluding coarse fragments; and

2. The color of the sodium-pyrophosphate extract on white

chromatographic or filter paper is below or to the right of a line

drawn to exclude blocks 5/1, 6/2, and 7/3 (Munsell

designations, fig. 2). If few or no fibers can be detected and the

color of the pyrophosphate extract is to the left of or above this

line, the possibility that the material is limnic must be

considered.

Humilluvic Material

Humilluvic material, i.e., illuvial humus, accumulates in the

lower parts of some organic soils that are acid and have been

drained and cultivated. The humilluvic material has a C14 age

that is not older than the overlying organic materials. It has very

high solubility in sodium pyrophosphate and rewets very slowly

after drying. Most commonly, it accumulates near a contact

with a sandy mineral horizon.

Figure 2.—Value and chroma of pyrophosphate solution of fibric and

sapric materials.
22 Keys to Soil Taxonomy

To be recognized as a differentia in classification, the

humilluvic material must constitute one-half or more (by

volume) of a layer 2 cm or more thick.

Limnic Materials

The presence or absence of limnic deposits is taken into

account in the higher categories of Histosols but not Histels.

The nature of such deposits is considered in the lower

categories of Histosols. Limnic materials include both organic

and inorganic materials that were either (1) deposited in water

by precipitation or through the action of aquatic organisms,

such as algae or diatoms, or (2) derived from underwater and

floating aquatic plants and subsequently modified by aquatic

animals. They include coprogenous earth (sedimentary peat),

diatomaceous earth, and marl.

Coprogenous Earth

A layer of coprogenous earth (sedimentary peat) is a limnic

layer that:

1. Contains many fecal pellets with diameters between a few

hundredths and a few tenths of a millimeter; and

2. Has a color value, moist, of 4 or less; and

3. Either forms a slightly viscous water suspension and is

nonplastic or slightly plastic but not sticky, or shrinks upon

drying, forming clods that are difficult to rewet and often tend

to crack along horizontal planes; and

4. Either yields a saturated sodium-pyrophosphate extract on

white chromatographic or filter paper that has a color value of 7

or more and chroma of 2 or less (fig. 2) or has a cationexchange capacity of less than 240 cmol(+) per kg organic

matter (measured by loss on ignition), or both.

Diatomaceous Earth

A layer of diatomaceous earth is a limnic layer that:

1. If not previously dried, has a matrix color value of 3, 4,

or 5, which changes irreversibly on drying as a result of the

irreversible shrinkage of organic-matter coatings on diatoms

(identifiable by microscopic, 440 X, examination of dry

samples); and

2. Either yields a saturated sodium-pyrophosphate extract on

white chromatographic or filter paper that has a color value of 8

or more and chroma of 2 or less or has a cation-exchange

capacity of less than 240 cmol(+) per kg organic matter (by loss

on ignition), or both.

Marl

A layer of marl is a limnic layer that:

1. Has a color value, moist, of 5 or more; and

2. Reacts with dilute HCl to evolve CO2

.

The color of marl usually does not change irreversibly on

drying because a layer of marl contains too little organic matter,

even before it has been shrunk by drying, to coat the carbonate

particles.

Thickness of Organic Soil Materials

(Control Section of Histosols and Histels)

The thickness of organic materials over limnic materials,

mineral materials, water, or permafrost is used to define the

Histosols and Histels.

For practical reasons, an arbitrary control section has been

established for the classification of Histosols and Histels.

Depending on the kinds of soil material in the surface layer, the

control section has a thickness of either 130 cm or 160 cm from

the soil surface if there is no densic, lithic, or paralithic contact,

thick layer of water, or permafrost within the respective limit.

The thicker control section is used if the surface layer to a depth

of 60 cm either contains three-fourths or more fibers derived

from Sphagnum, Hypnum, or other mosses or has a bulk density

of less than 0.1. Layers of water, which may be between a few

centimeters and many meters thick in these soils, are considered

to be the lower boundary of the control section only if the water

extends below a depth of 130 or 160 cm, respectively. A densic,

lithic, or paralithic contact, if shallower than 130 or 160 cm,

constitutes the lower boundary of the control section. In some

soils the lower boundary is 25 cm below the upper limit of

permafrost. An unconsolidated mineral substratum shallower

than those limits does not change the lower boundary of the

control section.

The control section of Histosols and Histels is divided

somewhat arbitrarily into three tiers—surface, subsurface, and

bottom tiers.

Surface Tier

The surface tier of a Histosol or Histel extends from the soil

surface to a depth of 60 cm if either (1) the materials within that

depth are fibric and three-fourths or more of the fiber volume is

derived from Sphagnum or other mosses or (2) the materials

have a bulk density of less than 0.1. Otherwise, the surface tier

extends from the soil surface to a depth of 30 cm.

Some organic soils have a mineral surface layer less than 40

cm thick as a result of flooding, volcanic eruptions, additions of

mineral materials to increase soil strength or reduce the hazard

of frost, or other causes. If such a mineral layer is less than 30

cm thick, it constitutes the upper part of the surface tier; if it is

30 to 40 cm thick, it constitutes the whole surface tier and part

of the subsurface tier.
Horizons and Characteristics Diagnostic for the Higher Categories 23

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Subsurface Tier

The subsurface tier is normally 60 cm thick. If the control

section ends at a shallower depth (at a densic, lithic, or

paralithic contact or a water layer or in permafrost), however,

the subsurface tier extends from the lower boundary of the

surface tier to the lower boundary of the control section. It

includes any unconsolidated mineral layers that may be present

within those depths.

Bottom Tier

The bottom tier is 40 cm thick unless the control section has

its lower boundary at a shallower depth (at a densic, lithic, or

paralithic contact or a water layer or in permafrost).

Thus, if the organic materials are thick, there are two

possible thicknesses of the control section, depending on the

presence or absence and the thickness of a surface mantle of

fibric moss or other organic material that has a low bulk density

(less than 0.1). If the fibric moss extends to a depth of 60 cm

and is the dominant material within this depth (three-fourths or

more of the volume), the control section is 160 cm thick. If the

fibric moss is thin or absent, the control section extends to a

depth of 130 cm.

Horizons and Characteristics

Diagnostic for Both Mineral and

Organic Soils

Following are descriptions of the horizons and

characteristics that are diagnostic for both mineral and organic

soils.

Aquic Conditions

Soils with aquic (L. aqua, water) conditions are those that

currently undergo continuous or periodic saturation and

reduction. The presence of these conditions is indicated by

redoximorphic features, except in Histosols and Histels, and can

be verified by measuring saturation and reduction, except in

artificially drained soils. Artificial drainage is defined here as

the removal of free water from soils having aquic conditions by

surface mounding, ditches, or subsurface tiles to the extent that

water table levels are changed significantly in connection with

specific types of land use. In the keys, artificially drained soils

are included with soils that have aquic conditions.

Elements of aquic conditions are as follows:

1. Saturation is characterized by zero or positive pressure in

the soil water and can generally be determined by observing

free water in an unlined auger hole. Problems may arise,

however, in clayey soils with peds, where an unlined auger hole

may fill with water flowing along faces of peds while the soil

matrix is and remains unsaturated (bypass flow). Such free

water may incorrectly suggest the presence of a water table,

while the actual water table occurs at greater depth. Use of well

sealed piezometers or tensiometers is therefore recommended

for measuring saturation. Problems may still occur, however, if

water runs into piezometer slits near the bottom of the

piezometer hole or if tensiometers with slowly reacting

manometers are used. The first problem can be overcome by

using piezometers with smaller slits and the second by using

transducer tensiometry, which reacts faster than manometers.

Soils are considered wet if they have pressure heads greater

than -1 kPa. Only macropores, such as cracks between peds or

channels, are then filled with air, while the soil matrix is usually

still saturated. Obviously, exact measurements of the wet state

can be obtained only with tensiometers. For operational

purposes, the use of piezometers is recommended as a standard

method.

The duration of saturation required for creating aquic

conditions varies, depending on the soil environment, and is not

specified.

Three types of saturation are defined:

a. Endosaturation.—The soil is saturated with water in all

layers from the upper boundary of saturation to a depth of

200 cm or more from the mineral soil surface.

b. Episaturation.—The soil is saturated with water in one

or more layers within 200 cm of the mineral soil surface and

also has one or more unsaturated layers, with an upper

boundary above a depth of 200 cm, below the saturated

layer. The zone of saturation, i.e., the water table, is perched

on top of a relatively impermeable layer.

c. Anthric saturation.—This term refers to a special kind of

aquic conditions that occur in soils that are cultivated and

irrigated (flood irrigation). Soils with anthraquic conditions

must meet the requirements for aquic conditions and in

addition have both of the following:

(1) A tilled surface layer and a directly underlying

slowly permeable layer that has, for 3 months or more in

normal years, both:

(a) Saturation and reduction; and

(b) Chroma of 2 or less in the matrix; and

(2) A subsurface horizon with one or more of the

following:

(a) Redox depletions with a color value, moist, of 4

or more and chroma of 2 or less in macropores; or

(b) Redox concentrations of iron; or

(c) 2 times or more the amount of iron (by dithionite

citrate) contained in the tilled surface layer.

2. The degree of reduction in a soil can be characterized by

the direct measurement of redox potentials. Direct
24 Keys to Soil Taxonomy

measurements should take into account chemical equilibria as

expressed by stability diagrams in standard soil textbooks.

Reduction and oxidation processes are also a function of soil

pH. Obtaining accurate measurements of the degree of

reduction in a soil is difficult. In the context of this taxonomy,

however, only a degree of reduction that results in reduced iron

is considered, because it produces the visible redoximorphic

features that are identified in the keys. A simple field test is

available to determine if reduced iron ions are present. A freshly

broken surface of a field-wet soil sample is treated with

alpha,alpha-dipyridyl in neutral, 1-normal ammonium-acetate

solution. The appearance of a strong red color on the freshly

broken surface indicates the presence of reduced iron ions. A

positive reaction to the alpha,alpha-dipyridyl field test for

ferrous iron (Childs, 1981) may be used to confirm the

existence of reducing conditions and is especially useful in

situations where, despite saturation, normal morphological

indicators of such conditions are either absent or obscured (as

by the dark colors characteristic of melanic great groups). A

negative reaction, however, does not imply that reducing

conditions are always absent. It may only mean that the level of

free iron in the soil is below the sensitivity limit of the test or

that the soil is in an oxidized phase at the time of testing. Use of

alpha,alpha-dipyridyl in a 10 percent acetic-acid solution is not

recommended because the acid is likely to change soil

conditions, for example, by dissolving CaCO3

.

The duration of reduction required for creating aquic

conditions is not specified.

3. Redoximorphic features associated with wetness result

from alternating periods of reduction and oxidation of iron and

manganese compounds in the soil. Reduction occurs during

saturation with water, and oxidation occurs when the soil is not

saturated. The reduced iron and manganese ions are mobile and

may be transported by water as it moves through the soil.

Certain redox patterns occur as a function of the patterns in

which the ion-carrying water moves through the soil and as a

function of the location of aerated zones in the soil. Redox

patterns are also affected by the fact that manganese is reduced

more rapidly than iron, while iron oxidizes more rapidly upon

aeration. Characteristic color patterns are created by these

processes. The reduced iron and manganese ions may be

removed from a soil if vertical or lateral fluxes of water occur,

in which case there is no iron or manganese precipitation in that

soil. Wherever the iron and manganese are oxidized and

precipitated, they form either soft masses or hard concretions or

nodules. Movement of iron and manganese as a result of redox

processes in a soil may result in redoximorphic features that are

defined as follows:

a. Redox concentrations.—These are zones of apparent

accumulation of Fe-Mn oxides, including:

(1) Nodules and concretions, which are cemented

bodies that can be removed from the soil intact.

Concretions are distinguished from nodules on the basis

of internal organization. A concretion typically has

concentric layers that are visible to the naked eye.

Nodules do not have visible organized internal structure.

Boundaries commonly are diffuse if formed in situ and

sharp after pedoturbation. Sharp boundaries may be relict

features in some soils; and

(2) Masses, which are noncemented concentrations of

substances within the soil matrix; and

(3) Pore linings, i.e., zones of accumulation along pores

that may be either coatings on pore surfaces or

impregnations from the matrix adjacent to the pores.

b. Redox depletions.—These are zones of low chroma

(chromas less than those in the matrix) where either Fe-Mn

oxides alone or both Fe-Mn oxides and clay have been

stripped out, including:

(1) Iron depletions, i.e., zones that contain low amounts

of Fe and Mn oxides but have a clay content similar to

that of the adjacent matrix (often referred to as albans or

neoalbans); and

(2) Clay depletions, i.e., zones that contain low amounts

of Fe, Mn, and clay (often referred to as silt coatings or

skeletans).

c. Reduced matrix.—This is a soil matrix that has low

chroma in situ but undergoes a change in hue or chroma

within 30 minutes after the soil material has been exposed to

air.

d. In soils that have no visible redoximorphic features, a

reaction to an alpha,alpha-dipyridyl solution satisfies the

requirement for redoximorphic features.

Field experience indicates that it is not possible to define a

specific set of redoximorphic features that is uniquely

characteristic of all of the taxa in one particular category.

Therefore, color patterns that are unique to specific taxa are

referenced in the keys.

Anthraquic conditions are a variant of episaturation and are

associated with controlled flooding (for such crops as wetland

rice and cranberries), which causes reduction processes in the

saturated, puddled surface soil and oxidation of reduced and

mobilized iron and manganese in the unsaturated subsoil.

Cryoturbation

Cryoturbation (frost churning) is the mixing of the soil

matrix within the pedon that results in irregular or broken

horizons, involutions, accumulation of organic matter on the

permafrost table, oriented rock fragments, and silt caps on rock

fragments.
Horizons and Characteristics Diagnostic for the Higher Categories 25

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Densic Contact

A densic contact (L. densus, thick) is a contact between soil

and densic materials (defined below). It has no cracks, or the

spacing of cracks that roots can enter is 10 cm or more.

Densic Materials

Densic materials are relatively unaltered materials (do not

meet the requirements for any other named diagnostic horizons

or any other diagnostic soil characteristic) that have a

noncemented rupture-resistance class. The bulk density or the

organization is such that roots cannot enter, except in cracks.

These are mostly earthy materials, such as till, volcanic

mudflows, and some mechanically compacted materials, for

example, mine spoils. Some noncemented rocks can be densic

materials if they are dense or resistant enough to keep roots

from entering, except in cracks.

Densic materials are noncemented and thus differ from

paralithic materials and the material below a lithic contact, both

of which are cemented.

Densic materials have, at their upper boundary, a densic

contact if they have no cracks or if the spacing of cracks that

roots can enter is 10 cm or more. These materials can be used to

differentiate soil series if the materials are within the series

control section.

Gelic Materials

Gelic materials are mineral or organic soil materials that

show evidence of cryoturbation (frost churning) and/or ice

segregation in the active layer (seasonal thaw layer) and/or the

upper part of the permafrost. Cryoturbation is manifested by

irregular and broken horizons, involutions, accumulation of

organic matter on top of and within the permafrost, oriented

rock fragments, and silt-enriched layers. The characteristic

structures associated with gelic materials include platy, blocky,

or granular macrostructures; the structural results of sorting;

and orbiculic, conglomeric, banded, or vesicular microfabrics.

Ice segregation is manifested by ice lenses, vein ice, segregated

ice crystals, and ice wedges. Cryopedogenic processes that lead

to gelic materials are driven by the physical volume change of

water to ice, moisture migration along a thermal gradient in the

frozen system, or thermal contraction of the frozen material by

continued rapid cooling.

Glacic Layer

A glacic layer is massive ice or ground ice in the form of ice

lenses or wedges. The layer is 30 cm or more thick and contains

75 percent or more visible ice.

Lithic Contact

A lithic contact is the boundary between soil and a coherent

underlying material. Except in Ruptic-Lithic subgroups, the

underlying material must be virtually continuous within the

limits of a pedon. Cracks that can be penetrated by roots are

few, and their horizontal spacing is 10 cm or more. The

underlying material must be sufficiently coherent when moist to

make hand-digging with a spade impractical, although the

material may be chipped or scraped with a spade. The material

below a lithic contact must be in a strongly cemented or more

cemented rupture-resistance class. Commonly, the material is

indurated. The underlying material considered here does not

include diagnostic soil horizons, such as a duripan or a

petrocalcic horizon.

A lithic contact is diagnostic at the subgroup level if it is

within 125 cm of the mineral soil surface in Oxisols and within

50 cm of the mineral soil surface in all other mineral soils. In

organic soils the lithic contact must be within the control

section to be recognized at the subgroup level.

Paralithic Contact

A paralithic (lithiclike) contact is a contact between soil and

paralithic materials (defined below) where the paralithic

materials have no cracks or the spacing of cracks that roots can

enter is 10 cm or more.

Paralithic Materials

Paralithic materials are relatively unaltered materials (do not

meet the requirements for any other named diagnostic horizons

or any other diagnostic soil characteristic) that have an

extremely weakly cemented to moderately cemented ruptureresistance class. Cementation, bulk density, and the organization

are such that roots cannot enter, except in cracks. Paralithic

materials have, at their upper boundary, a paralithic contact if

they have no cracks or if the spacing of cracks that roots can

enter is 10 cm or more. Commonly, these materials are partially

weathered bedrock or weakly consolidated bedrock, such as

sandstone, siltstone, or shale. Paralithic materials can be used to

differentiate soil series if the materials are within the series

control section. Fragments of paralithic materials 2.0 mm or

more in diameter are referred to as pararock fragments.

Permafrost

Permafrost is defined as a thermal condition in which a

material (including soil material) remains below 0 oC for 2 or

more years in succession. Those gelic materials having

permafrost contain the unfrozen soil solution that drives

cryopedogenic processes. Permafrost may be cemented by ice
26 Keys to Soil Taxonomy

or, in the case of insufficient interstitial water, may be dry. The

frozen layer has a variety of ice lenses, vein ice, segregated ice

crystals, and ice wedges. The permafrost table is in dynamic

equilibrium with the environment.

Soil Moisture Regimes

The term “soil moisture regime” refers to the presence or

absence either of ground water or of water held at a tension of

less than 1500 kPa in the soil or in specific horizons during

periods of the year. Water held at a tension of 1500 kPa or more

is not available to keep most mesophytic plants alive. The

availability of water is also affected by dissolved salts. If a soil

is saturated with water that is too salty to be available to most

plants, it is considered salty rather than dry. Consequently, a

horizon is considered dry when the moisture tension is 1500

kPa or more and is considered moist if water is held at a tension

of less than 1500 kPa but more than zero. A soil may be

continuously moist in some or all horizons either throughout the

year or for some part of the year. It may be either moist in

winter and dry in summer or the reverse. In the Northern

Hemisphere, summer refers to June, July, and August and

winter refers to December, January, and February.

Normal Years

In the discussions that follow and throughout the keys, the

term “normal years” is used. A normal year is defined as a year

that has plus or minus one standard deviation of the long-term

mean annual precipitation. (Long-term refers to 30 years or

more.) Also, the mean monthly precipitation during a normal

year must be plus or minus one standard deviation of the longterm monthly precipitation for 8 of the 12 months. For the most

part, normal years can be calculated from the mean annual

precipitation. When catastrophic events occur during a year,

however, the standard deviations of the monthly means should

also be calculated. The term “normal years” replaces the terms

“most years” and “6 out of 10 years,” which were used in the

1975 edition of Soil Taxonomy (USDA, SCS, 1975).

Soil Moisture Control Section

The intent in defining the soil moisture control section is to

facilitate estimation of soil moisture regimes from climatic data.

The upper boundary of this control section is the depth to which

a dry (tension of more than 1500 kPa, but not air-dry) soil will

be moistened by 2.5 cm of water within 24 hours. The lower

boundary is the depth to which a dry soil will be moistened by

7.5 cm of water within 48 hours. These depths do not include

the depth of moistening along any cracks or animal burrows

that are open to the surface.

If 7.5 cm of water moistens the soil to a densic, lithic,

paralithic, or petroferric contact or to a petrocalcic or

petrogypsic horizon or a duripan, the contact or the upper

boundary of the cemented horizon constitutes the lower

boundary of the soil moisture control section. If a soil is

moistened to one of these contacts or horizons by 2.5 cm of

water, the soil moisture control section is the boundary or the

contact itself. The control section of such a soil is considered

moist if the contact or upper boundary of the cemented horizon

has a thin film of water. If that upper boundary is dry, the

control section is considered dry.

The moisture control section of a soil extends approximately

(1) from 10 to 30 cm below the soil surface if the particle-size

class of the soil is fine-loamy, coarse-silty, fine-silty, or clayey;

(2) from 20 to 60 cm if the particle-size class is coarse-loamy;

and (3) from 30 to 90 cm if the particle-size class is sandy. If

the soil contains rock and pararock fragments that do not absorb

and release water, the limits of the moisture control section are

deeper. The limits of the soil moisture control section are

affected not only by the particle-size class but also by

differences in soil structure or pore-size distribution or by other

factors that influence the movement and retention of water in

the soil.

Classes of Soil Moisture Regimes

The soil moisture regimes are defined in terms of the level of

ground water and in terms of the seasonal presence or absence

of water held at a tension of less than 1500 kPa in the moisture

control section. It is assumed in the definitions that the soil

supports whatever vegetation it is capable of supporting, i.e.,

crops, grass, or native vegetation, and that the amount of stored

moisture is not being increased by irrigation or fallowing. These

cultural practices affect the soil moisture conditions as long as

they are continued.

Aquic moisture regime.—The aquic (L. aqua, water)

moisture regime is a reducing regime in a soil that is virtually

free of dissolved oxygen because it is saturated by water. Some

soils are saturated with water at times while dissolved oxygen is

present, either because the water is moving or because the

environment is unfavorable for micro-organisms (e.g., if the

temperature is less than 1 o

C); such a regime is not considered

aquic.

It is not known how long a soil must be saturated before it is

said to have an aquic moisture regime, but the duration must be

at least a few days, because it is implicit in the concept that

dissolved oxygen is virtually absent. Because dissolved oxygen

is removed from ground water by respiration of microorganisms, roots, and soil fauna, it is also implicit in the

concept that the soil temperature is above biologic zero for

some time while the soil is saturated. Biologic zero is defined as

5 oC in this taxonomy. In some of the very cold regions of the

world, however, biological activity occurs at temperatures

below 5 oC.

Very commonly, the level of ground water fluctuates with the

seasons; it is highest in the rainy season or in fall, winter, or

spring if cold weather virtually stops evapotranspiration. There

are soils, however, in which the ground water is always at or
Horizons and Characteristics Diagnostic for the Higher Categories 27

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very close to the surface. Examples are soils in tidal marshes or

in closed, landlocked depressions fed by perennial streams.

Such soils are considered to have a peraquic moisture regime.

Aridic and torric (L. aridus, dry, and L. torridus, hot and

dry) moisture regimes.—These terms are used for the same

moisture regime but in different categories of the taxonomy.

In the aridic (torric) moisture regime, the moisture control

section is, in normal years:

1. Dry in all parts for more than half of the cumulative days

per year when the soil temperature at a depth of 50 cm from the

soil surface is above 5 o

C; and

2. Moist in some or all parts for less than 90 consecutive days

when the soil temperature at a depth of 50 cm is above 8 oC.

Soils that have an aridic (torric) moisture regime normally

occur in areas of arid climates. A few are in areas of semiarid

climates and either have physical properties that keep them dry,

such as a crusty surface that virtually precludes the infiltration

of water, or are on steep slopes where runoff is high. There is

little or no leaching in this moisture regime, and soluble salts

accumulate in the soils if there is a source.

The limits set for soil temperature exclude from these

moisture regimes soils in the very cold and dry polar regions

and in areas at high elevations. Such soils are considered to

have anhydrous conditions (defined earlier).

Udic moisture regime.—The udic (L. udus, humid)

moisture regime is one in which the soil moisture control

section is not dry in any part for as long as 90 cumulative days

in normal years. If the mean annual soil temperature is lower

than 22 o

C and if the mean winter and mean summer soil

temperatures at a depth of 50 cm from the soil surface differ by

6 oC or more, the soil moisture control section, in normal years,

is dry in all parts for less than 45 consecutive days in the 4

months following the summer solstice. In addition, the udic

moisture regime requires, except for short periods, a threephase system, solid-liquid-gas, in part or all of the soil moisture

control section when the soil temperature is above 5 oC.

The udic moisture regime is common to the soils of humid

climates that have well distributed rainfall; have enough rain in

summer so that the amount of stored moisture plus rainfall is

approximately equal to, or exceeds, the amount of

evapotranspiration; or have adequate winter rains to recharge

the soils and cool, foggy summers, as in coastal areas. Water

moves downward through the soils at some time in normal

years.

In climates where precipitation exceeds evapotranspiration in

all months of normal years, the moisture tension rarely reaches

100 kPa in the soil moisture control section, although there are

occasional brief periods when some stored moisture is used.

The water moves through the soil in all months when it is not

frozen. Such an extremely wet moisture regime is called

perudic (L. per, throughout in time, and L. udus, humid). In the

names of most taxa, the formative element “ud” is used to

indicate either a udic or a perudic regime; the formative element

“per” is used in selected taxa.

Ustic moisture regime.—The ustic (L. ustus, burnt;

implying dryness) moisture regime is intermediate between the

aridic regime and the udic regime. Its concept is one of

moisture that is limited but is present at a time when conditions

are suitable for plant growth. The concept of the ustic moisture

regime is not applied to soils that have permafrost (defined

above).

If the mean annual soil temperature is 22 oC or higher or if

the mean summer and winter soil temperatures differ by less

than 6 oC at a depth of 50 cm below the soil surface, the soil

moisture control section in areas of the ustic moisture regime is

dry in some or all parts for 90 or more cumulative days in

normal years. It is moist, however, in some part either for more

than 180 cumulative days per year or for 90 or more

consecutive days.

If the mean annual soil temperature is lower than 22 oC and

if the mean summer and winter soil temperatures differ by 6 oC

or more at a depth of 50 cm from the soil surface, the soil

moisture control section in areas of the ustic moisture regime is

dry in some or all parts for 90 or more cumulative days in

normal years, but it is not dry in all parts for more than half of

the cumulative days when the soil temperature at a depth of 50

cm is higher than 5 oC. If in normal years the moisture control

section is moist in all parts for 45 or more consecutive days in

the 4 months following the winter solstice, the moisture control

section is dry in all parts for less than 45 consecutive days in the

4 months following the summer solstice.

In tropical and subtropical regions that have a monsoon

climate with either one or two dry seasons, summer and winter

seasons have little meaning. In those regions the moisture

regime is ustic if there is at least one rainy season of 3 months

or more. In temperate regions of subhumid or semiarid

climates, the rainy seasons are usually spring and summer or

spring and fall, but never winter. Native plants are mostly

annuals or plants that have a dormant period while the soil is

dry.

Xeric moisture regime.—The xeric (Gr. xeros, dry)

moisture regime is the typical moisture regime in areas of

Mediterranean climates, where winters are moist and cool and

summers are warm and dry. The moisture, which falls during

the winter, when potential evapotranspiration is at a minimum,

is particularly effective for leaching. In areas of a xeric moisture

regime, the soil moisture control section, in normal years, is dry

in all parts for 45 or more consecutive days in the 4 months

following the summer solstice and moist in all parts for 45 or

more consecutive days in the 4 months following the winter

solstice. Also, in normal years, the moisture control section is

moist in some part for more than half of the cumulative days

per year when the soil temperature at a depth of 50 cm from

the soil surface is higher than 5 o

C or for 90 or more

consecutive days when the soil temperature at a depth of 50 cm

is higher than 8 oC. The mean annual soil temperature is lower
28 Keys to Soil Taxonomy

than 22 oC, and the mean summer and mean winter soil

temperatures differ by 6 oC or more either at a depth of 50 cm

from the soil surface or at a densic, lithic, or paralithic contact if

shallower.

Soil Temperature Regimes

Classes of Soil Temperature Regimes

Following is a description of the soil temperature regimes

used in defining classes at various categoric levels in this

taxonomy.

Cryic (Gr. kryos, coldness; meaning very cold soils).—

Soils in this temperature regime have a mean annual

temperature lower than 8 oC but do not have permafrost.

1. In mineral soils the mean summer soil temperature (June,

July, and August in the Northern Hemisphere and December,

January, and February in the Southern Hemisphere) either at a

depth of 50 cm from the soil surface or at a densic, lithic, or

paralithic contact, whichever is shallower, is as follows:

a. If the soil is not saturated with water during some part of

the summer and

(1) If there is no O horizon: lower than 15 oC; or

(2) If there is an O horizon: lower than 8 oC; or

b. If the soil is saturated with water during some part of the

summer and

(1) If there is no O horizon: lower than 13 oC; or

(2) If there is an O horizon or a histic epipedon: lower

than 6 oC.

2. In organic soils the mean annual soil temperature is lower

than 6 oC.

Cryic soils that have an aquic moisture regime commonly

are churned by frost.

Isofrigid soils could also have a cryic temperature regime. A

few with organic materials in the upper part are exceptions.

The concepts of the soil temperature regimes described

below are used in defining classes of soils in the low categories.

Frigid.—A soil with a frigid temperature regime is

warmer in summer than a soil with a cryic regime, but its

mean annual temperature is lower than 8 o

C and the difference

between mean summer (June, July, and August) and mean

winter (December, January, and February) soil temperatures is

more than 6 oC either at a depth of 50 cm from the soil surface

or at a densic, lithic, or paralithic contact, whichever is

shallower.

Mesic.—The mean annual soil temperature is 8 oC or higher

but lower than 15 oC, and the difference between mean summer

and mean winter soil temperatures is more than 6 oC either at a

depth of 50 cm from the soil surface or at a densic, lithic, or

paralithic contact, whichever is shallower.

Thermic.—The mean annual soil temperature is 15 oC or

higher but lower than 22 oC, and the difference between mean

summer and mean winter soil temperatures is more than 6 oC

either at a depth of 50 cm from the soil surface or at a densic,

lithic, or paralithic contact, whichever is shallower.

Hyperthermic.—The mean annual soil temperature is

22 oC or higher, and the difference between mean summer and

mean winter soil temperatures is more than 6 oC either at a

depth of 50 cm from the soil surface or at a densic, lithic, or

paralithic contact, whichever is shallower.

If the name of a soil temperature regime has the prefix iso,

the mean summer and mean winter soil temperatures differ by

less than 6 oC at a depth of 50 cm or at a densic, lithic, or

paralithic contact, whichever is shallower.

Isofrigid.—The mean annual soil temperature is lower than

8 oC.

Isomesic.—The mean annual soil temperature is 8 oC or

higher but lower than 15 oC.

Isothermic.—The mean annual soil temperature is 15 oC or

higher but lower than 22 oC.

Isohyperthermic.—The mean annual soil temperature is

22 oC or higher.

Sulfidic Materials

Sulfidic materials contain oxidizable sulfur compounds.

They are mineral or organic soil materials that have a pH value

of more than 3.5 and that, if incubated as a layer 1 cm thick

under moist aerobic conditions (field capacity) at room

temperature, show a drop in pH of 0.5 or more units to a pH

value of 4.0 or less (1:1 by weight in water or in a minimum of

water to permit measurement) within 8 weeks.

Sulfidic materials accumulate as a soil or sediment that is

permanently saturated, generally with brackish water. The

sulfates in the water are biologically reduced to sulfides as the

materials accumulate. Sulfidic materials most commonly

accumulate in coastal marshes near the mouth of rivers that

carry noncalcareous sediments, but they may occur in

freshwater marshes if there is sulfur in the water. Upland

sulfidic materials may have accumulated in a similar manner in

the geologic past.

If a soil containing sulfidic materials is drained or if sulfidic

materials are otherwise exposed to aerobic conditions, the

sulfides oxidize and form sulfuric acid. The pH value, which

normally is near neutrality before drainage or exposure, may

drop below 3. The acid may induce the formation of iron and

aluminum sulfates. The iron sulfate, jarosite, may segregate,

forming the yellow redoximorphic concentrations that

commonly characterize a sulfuric horizon. The transition from

sulfidic materials to a sulfuric horizon normally requires very
Horizons and Characteristics Diagnostic for the Higher Categories 29

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few years and may occur within a few weeks. A sample of

sulfidic materials, if air-dried slowly in shade for about 2

months with occasional remoistening, becomes extremely

acid.

Sulfuric Horizon

Required Characteristics

The sulfuric (L. sulfur) horizon is 15 cm or more thick and is

composed of either mineral or organic soil material that has a

pH value of 3.5 or less (1:1 by weight in water or in a minimum

of water to permit measurement) and shows evidence that the

low pH value is caused by sulfuric acid. The evidence is one or

both of the following:

1. The horizon has:

a. Concentrations of jarosite, schwertmannite, and other

iron sulfates, hydroxisulfates, and elemental sulfur; or

b. Concentrations with a Munsell hue of 2.5Y or 5Y and a

chroma of 6 or more, moist; or

c. 0.05 percent or more water-soluble sulfate; or

2. The layer directly underlying the horizon consists of

sulfidic materials (defined above).

Literature Cited

Brewer, R. 1976. Fabric and Mineral Analysis of Soils.

Second edition. John Wiley and Sons, Inc. New York, New

York.

Burt, R., ed. 2004 Soil Survey Laboratory Methods Manual.

Soil Survey Investigations Report 42, Version 4.0. United States

Department of Agriculture, Natural Resources Conservation

Service, National Soil Survey Center.

Childs, C.W. 1981. Field Test for Ferrous Iron and FerricOrganic Complexes (on Exchange Sites or in Water-Soluble

Forms) in Soils. Austr. J. of Soil Res. 19: 175-180.

Pons, L.J., and I.S. Zonneveld. 1965. Soil Ripening

and Soil Classification. Initial Soil Formation in Alluvial

Deposits and a Classification of the Resulting Soils. Int. Inst.

Land Reclam. and Impr. Pub. 13. Wageningen, The

Netherlands.

United States Department of Agriculture, Soil Conservation

Service. 1975. Soil Taxonomy: A Basic System of Soil

Classification for Making and Interpreting Soil Surveys. Soil

Surv. Staff. U.S. Dep. Agric. Handb. 436.

United States Department of Agriculture, Soil Conservation

Service. 1993. Soil Survey Manual. Soil Surv. Div. Staff. U.S.

Dep. Agric. Handb. 18.

31

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The taxonomic class of a specific soil can be determined

by using the keys that follow in this and other chapters. It is

assumed that the reader is familiar with the definitions of

diagnostic horizons and properties that are given in chapters 2

and 3 of this publication and with the meanings of the terms

used for describing soils given in the Soil Survey Manual. The

Index at the back of this publication indicates the pages on

which definitions of terms are given.

Standard rounding conventions should be used to determine

numerical values.

Soil colors (hue, value, and chroma) are used in many of

the criteria that follow. Soil colors typically change value and

some change hue and chroma, depending on the water state.

In many of the criteria of the keys, the water state is specified.

If no water state is specified, the soil is considered to meet

the criterion if it does so when moist or dry or both moist and

dry.

All of the keys in this taxonomy are designed in such a way

that the user can determine the correct classification of a soil by

going through the keys systematically. The user must start at the

beginning of the “Key to Soil Orders” and eliminate, one by

one, all classes that include criteria that do not fit the soil in

question. The soil belongs to the first class listed for which it

meets all the required criteria.

In classifying a specific soil, the user of soil taxonomy

begins by checking through the “Key to Soil Orders” to

determine the name of the first order that, according to the

criteria listed, includes the soil in question. The next step is

to go to the page indicated to find the “Key to Suborders” of

that particular order. Then the user systematically goes through

the key to identify the suborder that includes the soil, i.e., the

first in the list for which it meets all the required criteria. The

same procedure is used to find the great group class of the soil

in the “Key to Great Groups” of the identified suborder.

Likewise, going through the “Key to Subgroups” of that great

group, the user selects as the correct subgroup name the name

of the first taxon for which the soil meets all of the required

criteria.

The family level is determined, in a similar manner, after the

subgroup has been determined. Chapter 17 can be used,

as one would use other keys in this taxonomy, to determine

which components are part of the family. The family,

however, typically has more than one component, and

therefore the entire chapter must be used. The keys to control

sections for classes used as components of a family must be

used to determine the control section before use of the keys to

classes.

The descriptions and definitions of individual soil series are

not included in this text. Definitions of the series and of the

control section are given in chapter 17.

In the “Key to Soil Orders” and the other keys that follow, the

diagnostic horizons and the properties mentioned do not include

those below any densic, lithic, paralithic, or petroferric contact.

The properties of buried soils and the properties of a surface

mantle are considered on the basis of whether or not the soil

meets the meaning of the term “buried soil” given in chapter 1.

If a soil has a surface mantle and is not a buried soil, the top

of the original surface layer is considered the “soil surface” for

determining depth to and thickness of diagnostic horizons and

most other diagnostic soil characteristics. The only properties of

the surface mantle that are considered are soil temperature, soil

moisture (including aquic conditions), and any andic or

vitrandic properties and family criteria.

If a soil profile includes a buried soil, the present soil surface

is used to determine soil moisture and temperature as well as

depth to and thickness of diagnostic horizons and other

diagnostic soil characteristics. Diagnostic horizons of the buried

soil are not considered in selecting taxa unless the criteria in the

keys specifically indicate buried horizons, such as in ThaptoHistic subgroups. Most other diagnostic soil characteristics of

the buried soil are not considered, but organic carbon if of

Holocene age, andic soil properties, base saturation, and all

properties used to determine family and series placement are

considered.

Key to Soil Orders

A. Soils that have:

1. Permafrost within 100 cm of the soil surface; or

2. Gelic materials within 100 cm of the soil surface and

permafrost within 200 cm of the soil surface.

Gelisols, p. 143

B. Other soils that:

1. Do not have andic soil properties in 60 percent or more

of the thickness between the soil surface and either a depth

of 60 cm or a densic, lithic, or paralithic contact or duripan if

shallower; and

CHAPTER 4

Identification of the Taxonomic Class of a Soil
32 Keys to Soil Taxonomy

2. Have organic soil materials that meet one or more of the

following:

a. Overlie cindery, fragmental, or pumiceous materials

and/or fill their interstices1 and directly below these

materials, have a densic, lithic, or paralithic contact; or

b. When added with the underlying cindery, fragmental,

or pumiceous materials, total 40 cm or more between the

soil surface and a depth of 50 cm; or

c. Constitute two-thirds or more of the total thickness of

the soil to a densic, lithic, or paralithic contact and have

no mineral horizons or have mineral horizons with a total

thickness of 10 cm or less; or

d. Are saturated with water for 30 days or more per year

in normal years (or are artificially drained), have an upper

boundary within 40 cm of the soil surface, and have a

total thickness of either:

(1) 60 cm or more if three-fourths or more of their

volume consists of moss fibers or if their bulk density,

moist, is less than 0.1 g/cm3; or

(2) 40 cm or more if they consist either of sapric or

hemic materials, or of fibric materials with less than

three-fourths (by volume) moss fibers and a bulk

density, moist, of 0.1 g/cm3 or more.

Histosols, p. 153

C. Other soils that do not have a plaggen epipedon or an

argillic or kandic horizon above a spodic horizon, and have one

or more of the following:

1. A spodic horizon, an albic horizon in 50 percent or

more of each pedon, and a cryic soil temperature regime;

or

2. An Ap horizon containing 85 percent or more spodic

materials; or

3. A spodic horizon with all of the following

characteristics:

a. One or more of the following:

(1) A thickness of 10 cm or more; or

(2) An overlying Ap horizon; or

(3) Cementation in 50 percent or more of each

pedon; or

(4) A coarse-loamy, loamy-skeletal, or finer particlesize class and a frigid temperature regime in the soil;

or

(5) A cryic temperature regime in the soil; and

b. An upper boundary within the following depths from

the mineral soil surface: either

(1) Less than 50 cm; or

(2) Less than 200 cm if the soil has a sandy particlesize class in at least some part between the mineral soil

surface and the spodic horizon; and

c. A lower boundary as follows:

(1) Either at a depth of 25 cm or more below the

mineral soil surface or at the top of a duripan or

fragipan or at a densic, lithic, paralithic, or petroferric

contact, whichever is shallowest; or

(2) At any depth,

(a) If the spodic horizon has a coarse-loamy,

loamy-skeletal, or finer particle-size class and the

soil has a frigid temperature regime; or

(b) If the soil has a cryic temperature regime; and

d. Either:

(1) A directly overlying albic horizon in 50 percent

or more of each pedon; or

(2) No andic soil properties in 60 percent or more of

the thickness either:

(a) Within 60 cm either of the mineral soil surface

or of the top of an organic layer with andic soil

properties, whichever is shallower, if there is no

densic, lithic, or paralithic contact, duripan, or

petrocalcic horizon within that depth; or

(b) Between either the mineral soil surface or the

top of an organic layer with andic soil properties,

whichever is shallower, and a densic, lithic, or

paralithic contact, a duripan, or a petrocalcic

horizon.

Spodosols, p. 251

D. Other soils that have andic soil properties in 60 percent or

more of the thickness either:

1. Within 60 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever

is shallower, if there is no densic, lithic, or paralithic contact,

duripan, or petrocalcic horizon within that depth; or

2. Between either the mineral soil surface or the top of an

organic layer with andic soil properties, whichever is

shallower, and a densic, lithic, or paralithic contact, a

duripan, or a petrocalcic horizon.

Andisols, p. 77

E. Other soils that have either:

1 Materials that meet the definition of cindery, fragmental, or pumiceous but have more

than 10 percent, by volume, voids that are filled with organic soil materials are considered

to be organic soil materials.
Identification of the Taxonomic Class of a Soil 33

I

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E

1. An oxic horizon that has its upper boundary within 150

cm of the mineral soil surface and no kandic horizon that has

its upper boundary within that depth; or

2. 40 percent or more (by weight) clay in the fine-earth

fraction between the mineral soil surface and a depth of 18

cm (after mixing) and a kandic horizon that has the

weatherable-mineral properties of an oxic horizon and has its

upper boundary within 100 cm of the mineral soil surface.

Oxisols, p. 235

F. Other soils that have:

1. A layer 25 cm or more thick, with an upper boundary

within 100 cm of the mineral soil surface, that has either

slickensides or wedge-shaped peds that have their long axes

tilted 10 to 60 degrees from the horizontal; and

2. A weighted average of 30 percent or more clay in the

fine-earth fraction either between the mineral soil surface

and a depth of 18 cm or in an Ap horizon, whichever is

thicker, and 30 percent or more clay in the fine-earth fraction

of all horizons between a depth of 18 cm and either a depth

of 50 cm or a densic, lithic, or paralithic contact, a duripan,

or a petrocalcic horizon if shallower; and

3. Cracks2

 that open and close periodically.

Vertisols, p. 283

G. Other soils that:

1. Have:

a. An aridic soil moisture regime; and

b. An ochric or anthropic epipedon; and

c. One or more of the following with the upper

boundary within 100 cm of the soil surface: a cambic

horizon with a lower depth of 25 cm or more; a cryic

temperature regime and a cambic horizon; a calcic,

gypsic, petrocalcic, petrogypsic, or salic horizon; or a

duripan; or

d. An argillic or natric horizon; or

2. Have a salic horizon; and

a. Saturation with water in one or more layers within

100 cm of the soil surface for 1 month or more during a

normal year; and

b. A moisture control section that is dry in some or all

parts at some time during normal years; and

c. No sulfuric horizon that has its upper boundary

within 150 cm of the mineral soil surface.

Aridisols, p. 97

H. Other soils that have either:

1. An argillic or kandic horizon, but no fragipan, and a

base saturation (by sum of cations) of less than 35 percent at

one of the following depths:

a. If the epipedon has a sandy or sandy-skeletal particlesize class throughout, either:

(1) 125 cm below the upper boundary of the argillic

horizon (but no deeper than 200 cm below the mineral

soil surface) or 180 cm below the mineral soil surface,

whichever is deeper; or

(2) At a densic, lithic, paralithic, or petroferric

contact if shallower; or

b. The shallowest of the following depths:

(1) 125 cm below the upper boundary of the argillic

or kandic horizon; or

(2) 180 cm below the mineral soil surface; or

(3) At a densic, lithic, paralithic, or petroferric

contact; or

2. A fragipan and both of the following:

a. Either an argillic or a kandic horizon above, within,

or below it or clay films 1 mm or more thick in one or

more of its subhorizons; and

b. A base saturation (by sum of cations) of less than

35 percent at the shallowest of the following depths:

(1) 75 cm below the upper boundary of the fragipan;

or

(2) 200 cm below the mineral soil surface; or

(3) At a densic, lithic, paralithic, or petroferric

contact.

Ultisols, p. 261

I. Other soils that have both of the following:

1. Either:

a. A mollic epipedon; or

b. Both a surface horizon that meets all the requirements

for a mollic epipedon except thickness after the soil has

been mixed to a depth of 18 cm and a subhorizon more

than 7.5 cm thick, within the upper part of an argillic,

kandic, or natric horizon, that meets the color, organiccarbon content, base saturation, and structure

requirements of a mollic epipedon but is separated from

the surface horizon by an albic horizon; and

2 A crack is a separation between gross polyhedrons. If the surface is strongly selfmulching, i.e., a mass of granules, or if the soil is cultivated while cracks are open, the

cracks may be filled mainly by granular materials from the surface, but they are open in the

sense that the polyhedrons are separated. A crack is regarded as open if it controls the

infiltration and percolation of water in a dry, clayey soil.
34

2. A base saturation of 50 percent or more (by NH4OAc) in

all horizons either between the upper boundary of any

argillic, kandic, or natric horizon and a depth of 125 cm

below that boundary, or between the mineral soil surface and

a depth of 180 cm, or between the mineral soil surface and a

densic, lithic, or paralithic contact, whichever depth is

shallowest.

Mollisols, p. 191

J. Other soils that do not have a plaggen epipedon and that

have either:

1. An argillic, kandic, or natric horizon; or

2. A fragipan that has clay films 1 mm or more thick in

some part.

Alfisols, p. 35

K. Other soils that have either:

1. One or more of the following:

a. A cambic horizon with its upper boundary within 100

cm of the mineral soil surface and its lower boundary at a

depth of 25 cm or more below the mineral soil surface; or

b. A calcic, petrocalcic, gypsic, petrogypsic, or

placic horizon or a duripan with an upper boundary

within a depth of 100 cm of the mineral soil surface; or

c. A fragipan or an oxic, sombric, or spodic horizon

with an upper boundary within 200 cm of the mineral soil

surface; or

d. A sulfuric horizon that has its upper boundary within

150 cm of the mineral soil surface; or

e. A cryic temperature regime and a cambic horizon; or

2. No sulfidic materials within 50 cm of the mineral soil

surface; and both:

a. In one or more horizons between 20 and 50 cm below

the mineral soil surface, either an n value of 0.7 or less or

less than 8 percent clay in the fine-earth fraction; and

b. One or both of the following:

(1) A salic horizon or a histic, mollic, plaggen, or

umbric epipedon; or

(2) In 50 percent or more of the layers between the

mineral soil surface and a depth of 50 cm, an

exchangeable sodium percentage of 15 or more (or a

sodium adsorption ratio of 13 or more), which

decreases with increasing depth below 50 cm, and also

ground water within 100 cm of the mineral soil surface

at some time during the year when the soil is not

frozen in any part.

Inceptisols, p. 159

L. Other soils.

Entisols, p. 123
35

A

L

F

Key to Suborders

JA. Alfisols that have, in one or more horizons within 50 cm

of the mineral soil surface, aquic conditions (other than

anthraquic conditions) for some time in normal years (or

artificial drainage) and have one or both of the following:

1. Redoximorphic features in all layers between either the

lower boundary of an Ap horizon or a depth of 25 cm below

the mineral soil surface, whichever is deeper, and a depth of

40 cm; and one of the following within the upper 12.5 cm of

the argillic, natric, glossic, or kandic horizon:

a. 50 percent or more redox depletions with chroma of 2

or less on faces of peds and redox concentrations within

peds; or

b. Redox concentrations and 50 percent or more

redox depletions with chroma of 2 or less in the matrix; or

c. 50 percent or more redox depletions with chroma of 1

or less on faces of peds or in the matrix, or both; or

2. In the horizons that have aquic conditions, enough active

ferrous iron to give a positive reaction to alpha,alphadipyridyl at a time when the soil is not being irrigated.

Aqualfs, p. 35

JB. Other Alfisols that have a cryic or isofrigid temperature

regime.

Cryalfs, p. 44

JC. Other Alfisols that have an ustic moisture regime.

Ustalfs, p. 59

JD. Other Alfisols that have a xeric moisture regime.

Xeralfs, p. 71

JE. Other Alfisols.

Udalfs, p. 47

Aqualfs

Key to Great Groups

JAA. Aqualfs that have a cryic temperature regime.

Cryaqualfs, p. 37

JAB. Other Aqualfs that have one or more horizons, at a

depth between 30 and 150 cm from the mineral soil surface, in

which plinthite either forms a continuous phase or constitutes

one-half or more of the volume.

Plinthaqualfs, p. 43

JAC. Other Aqualfs that have a duripan.

Duraqualfs, p. 37

JAD. Other Aqualfs that have a natric horizon.

Natraqualfs, p. 43

JAE. Other Aqualfs that have a fragipan with an upper

boundary within 100 cm of the mineral soil surface.

Fragiaqualfs, p. 41

JAF. Other Aqualfs that have a kandic horizon.

Kandiaqualfs, p. 42

JAG. Other Aqualfs that have one or more layers, at least 25

cm thick (cumulative) within 100 cm of the mineral soil

surface, that have 50 percent or more (by volume) recognizable

bioturbation, such as filled animal burrows, wormholes, or casts.

Vermaqualfs, p. 43

JAH. Other Aqualfs that have an abrupt textural change

between the ochric epipedon or the albic horizon and the

argillic horizon and have a moderately low or lower saturated

hydraulic conductivity in the argillic horizon.

Albaqualfs, p. 35

JAI. Other Aqualfs that have a glossic horizon.

Glossaqualfs, p. 41

JAJ. Other Aqualfs that have episaturation.

Epiaqualfs, p. 39

JAK. Other Aqualfs.

Endoaqualfs, p. 37

Albaqualfs

Key to Subgroups

JAHA. Albaqualfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

CHAPTER 5

Alfisols
36 Keys to Soil Taxonomy

mineral soil surface to the top of an argillic horizon at a depth

of 50 cm or more below the mineral soil surface.

Arenic Albaqualfs

JAHB. Other Albaqualfs that have both of the following:

1. One or both:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. Chroma of 3 or more in 40 percent or more of the matrix

between the lower boundary of the A or Ap horizon and a

depth of 75 cm from the mineral soil surface.

Aeric Vertic Albaqualfs

JAHC. Other Albaqualfs that have both of the following:

1. One or both:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. An Ap horizon or materials between the mineral soil

surface and a depth of 18 cm that, after mixing, have one or

more of the following:

a. A color value, moist, of 4 or more; or

b. A color value, dry, of 6 or more; or

c. Chroma of 4 or more.

Chromic Vertic Albaqualfs

JAHD. Other Albaqualfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Albaqualfs

JAHE. Other Albaqualfs that have both:

1. Chroma of 3 or more in 40 percent or more of the matrix

between the lower boundary of the A or Ap horizon and a

depth of 75 cm from the mineral soil surface; and

2. A mollic epipedon, or the upper 18 cm of the mineral

soil meets all of the requirements for a mollic epipedon,

except for thickness, after mixing.

Udollic Albaqualfs

JAHF. Other Albaqualfs that have chroma of 3 or more in 40

percent or more of the matrix between the lower boundary of

the A or Ap horizon and a depth of 75 cm from the mineral soil

surface.

Aeric Albaqualfs

JAHG. Other Albaqualfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Albaqualfs

JAHH. Other Albaqualfs that have a mollic epipedon, or the

upper 18 cm of the mineral soil meets all of the requirements

for a mollic epipedon, except for thickness, after mixing.

Mollic Albaqualfs

JAHI. Other Albaqualfs that have an umbric epipedon, or the

upper 18 cm of the mineral soil meets all of the requirements

for an umbric epipedon, except for thickness, after mixing.

Umbric Albaqualfs

JAHJ. Other Albaqualfs.

Typic Albaqualfs
Alfisols 37

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L

F

Cryaqualfs

Key to Subgroups

JAAA. All Cryaqualfs (provisionally).

Typic Cryaqualfs

Duraqualfs

Key to Subgroups

JACA. All Duraqualfs (provisionally).

Typic Duraqualfs

Endoaqualfs

Key to Subgroups

JAKA. Endoaqualfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, one or more of the

following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Endoaqualfs

JAKB. Other Endoaqualfs that have both of the following:

1. One or both:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. An Ap horizon or materials between the mineral soil

surface and a depth of 18 cm that, after mixing, have one or

more of the following:

a. A color value, moist, of 4 or more; or

b. A color value, dry, of 6 or more; or

c. Chroma of 4 or more.

Chromic Vertic Endoaqualfs

JAKC. Other Endoaqualfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Endoaqualfs

JAKD. Other Endoaqualfs that have:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. In one or more horizons between the A or Ap horizon

and a depth of 75 cm below the mineral soil surface, one or a

combination of the following colors:

a. Hue of 7.5YR or redder in 50 percent or more of the

matrix; and

(1) If peds are present, chroma of 2 or more on 50

percent or more of ped exteriors or no redox depletions

with chroma of 2 or less in ped interiors; or

(2) If peds are absent, chroma of 2 or more in 50

percent or more of the matrix; or

b. In 50 percent or more of the matrix, hue of 10YR or

yellower and either:

(1) Both a color value of 3 or more (moist) and

chroma of 3 or more (moist and dry); or

(2) Chroma of 2 or more if there are no redox

concentrations.

Aeric Fragic Endoaqualfs
38 Keys to Soil Taxonomy

JAKE. Other Endoaqualfs that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Endoaqualfs

JAKF. Other Endoaqualfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm below the mineral soil surface.

Arenic Endoaqualfs

JAKG. Other Endoaqualfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending

from the mineral soil surface to the top of an argillic

horizon at a depth of 100 cm or more below the mineral soil

surface.

Grossarenic Endoaqualfs

JAKH. Other Endoaqualfs that have both:

1. A mollic epipedon, or the upper 18 cm of the mineral

soil meets all of the requirements for a mollic epipedon,

except for thickness, after mixing; and

2. In one or more horizons between the A or Ap horizon

and a depth of 75 cm below the mineral soil surface, one or a

combination of the following colors:

a. Hue of 7.5YR or redder in 50 percent or more of the

matrix; and

(1) If peds are present, chroma of 2 or more on 50

percent or more of ped exteriors or no redox depletions

with chroma of 2 or less in ped interiors; or

(2) If peds are absent, chroma of 2 or more in 50

percent or more of the matrix; or

b. In 50 percent or more of the matrix, hue of 10YR or

yellower and either:

(1) Both a color value of 3 or more (moist) and

chroma of 3 or more; or

(2) Chroma of 2 or more if there are no redox

concentrations.

Udollic Endoaqualfs

JAKI. Other Endoaqualfs that have both:

1. An umbric epipedon, or the upper 18 cm of the mineral

soil meets all of the requirements for an umbric epipedon,

except for thickness, after mixing; and

2. In one or more horizons between the A or Ap horizon

and a depth of 75 cm below the mineral soil surface, one or a

combination of the following colors:

a. Hue of 7.5YR or redder in 50 percent or more of the

matrix; and

(1) If peds are present, chroma of 2 or more on 50

percent or more of ped exteriors or no redox depletions

with chroma of 2 or less in ped interiors; or

(2) If peds are absent, chroma of 2 or more in 50

percent or more of the matrix; or

b. In 50 percent or more of the matrix, hue of 10YR or

yellower and either:

(1) Both a color value of 3 or more (moist) and

chroma of 3 or more; or

(2) Chroma of 2 or more if there are no redox

concentrations.

Aeric Umbric Endoaqualfs

JAKJ. Other Endoaqualfs that have, in one or more horizons

between the A or Ap horizon and a depth of 75 cm below the

mineral soil surface, in 50 percent or more of the matrix, one or

a combination of the following colors:

1. Hue of 7.5YR or redder; and

a. If peds are present, chroma of 2 or more (both moist

and dry) on 50 percent or more of ped exteriors or no

redox depletions with chroma of 2 or less (both moist and

dry) in ped interiors; or

b. If peds are absent, chroma of 2 or more (both moist

and dry); or

2. Hue of 10YR or yellower and either:

a. Both a color value of 3 or more (moist) and chroma

of 3 or more (moist and dry); or

b. Chroma of 2 or more (both moist and dry) and no

redox concentrations.

Aeric Endoaqualfs

JAKK. Other Endoaqualfs that have a mollic epipedon, or the

upper 18 cm of the mineral soil meets all of the requirements

for a mollic epipedon, except for thickness, after mixing.

Mollic Endoaqualfs

JAKL. Other Endoaqualfs that have an umbric epipedon, or

the upper 18 cm of the mineral soil meets all of the

requirements for an umbric epipedon, except for thickness, after

mixing.

Umbric Endoaqualfs

JAKM. Other Endoaqualfs.

Typic Endoaqualfs
Alfisols 39

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Epiaqualfs

Key to Subgroups

JAJA. Epiaqualfs that have all of the following:

1. One or both:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. In one or more horizons between the A or Ap horizon

and a depth of 75 cm below the mineral soil surface, in 50

percent or more of the matrix, one or a combination of the

following colors:

a. Hue of 7.5YR or redder; and

(1) If peds are present, chroma of 2 or more (both

moist and dry) on 50 percent or more of ped exteriors

or no redox depletions with chroma of 2 or less (both

moist and dry) in ped interiors; or

(2) If peds are absent, chroma of 2 or more (both

moist and dry); or

b. Hue of 10YR or yellower and either:

(1) Both a color value of 3 or more (moist)

and chroma of 3 or more (moist and dry); or

(2) Chroma of 2 or more (both moist and dry) and no

redox concentrations; and

3. An Ap horizon or materials between the mineral soil

surface and a depth of 18 cm that, after mixing, have one or

more of the following:

a. A color value, moist, of 4 or more; or

b. A color value, dry, of 6 or more; or

c. Chroma of 4 or more.

Aeric Chromic Vertic Epiaqualfs

JAJB. Other Epiaqualfs that have both of the following:

1. One or both:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. In one or more horizons between the A or Ap horizon

and a depth of 75 cm below the mineral soil surface, in 50

percent or more of the matrix, one or a combination of the

following colors:

a. Hue of 7.5YR or redder; and

(1) If peds are present, chroma of 2 or more (both

moist and dry) on 50 percent or more of ped exteriors

or no redox depletions with chroma of 2 or less (both

moist and dry) in ped interiors; or

(2) If peds are absent, chroma of 2 or more (both

moist and dry); or

b. Hue of 10YR or yellower and either:

(1) Both a color value of 3 or more (moist) and

chroma of 3 or more (moist and dry); or

(2) Chroma of 2 or more (both moist and dry) and no

redox concentrations.

Aeric Vertic Epiaqualfs

JAJC. Other Epiaqualfs that have both of the following:

1. One or both:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. An Ap horizon or materials between the mineral soil

surface and a depth of 18 cm that, after mixing, have one or

more of the following:

a. A color value, moist, of 4 or more; or

b. A color value, dry, of 6 or more; or

c. Chroma of 4 or more.

Chromic Vertic Epiaqualfs
40 Keys to Soil Taxonomy

JAJD. Other Epiaqualfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Epiaqualfs

JAJE. Other Epiaqualfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, one or more of the

following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Epiaqualfs

JAJF. Other Epiaqualfs that have:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. In one or more horizons between the A or Ap horizon

and a depth of 75 cm below the mineral soil surface, in 50

percent or more of the matrix, one or a combination of the

following colors:

a. Hue of 7.5YR or redder; and

(1) If peds are present, chroma of 2 or more (both

moist and dry) on 50 percent or more of ped exteriors

or no redox depletions with chroma of 2 or less (both

moist and dry) in ped interiors; or

(2) If peds are absent, chroma of 2 or more (both

moist and dry); or

b. Hue of 10YR or yellower and either:

(1) Both a color value of 3 or more (moist) and

chroma of 3 or more (moist and dry); or

(2) Chroma of 2 or more (both moist and dry) and no

redox concentrations.

Aeric Fragic Epiaqualfs

JAJG. Other Epiaqualfs that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Epiaqualfs

JAJH. Other Epiaqualfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm below the mineral soil surface.

Arenic Epiaqualfs

JAJI. Other Epiaqualfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 100 cm or more below the mineral soil surface.

Grossarenic Epiaqualfs

JAJJ. Other Epiaqualfs that have:

1. An umbric epipedon, or the upper 18 cm of the mineral

soil meets all of the requirements for an umbric epipedon,

except for thickness, after mixing; and

2. In one or more horizons between the A or Ap horizon

and a depth of 75 cm below the mineral soil surface, in 50

percent or more of the matrix, one or a combination of the

following colors:

a. Hue of 7.5YR or redder; and

(1) If peds are present, chroma of 2 or more (both

moist and dry) on 50 percent or more of ped exteriors

or no redox depletions with chroma of 2 or less (both

moist and dry) in ped interiors; or

(2) If peds are absent, chroma of 2 or more (both

moist and dry); or

b. Hue of 10YR or yellower and either:
Alfisols 41

A

L

F

(1) Both a color value of 3 or more (moist) and

chroma of 3 or more (moist and dry); or

(2) Chroma of 2 or more (both moist and dry) and no

redox concentrations.

Aeric Umbric Epiaqualfs

JAJK. Other Epiaqualfs that have both:

1. A mollic epipedon, or the upper 18 cm of the mineral

soil meets all of the requirements for a mollic epipedon,

except for thickness, after mixing and

2. In 50 percent or more of the matrix in one or more

horizons between the A or Ap horizon and a depth of 75 cm

below the mineral soil surface, one or a combination of the

following colors:

a. Hue of 7.5YR or redder; and

(1) If peds are present, chroma of 2 or more on 50

percent or more of ped exteriors or no redox depletions

with chroma of 2 or less in ped interiors; or

(2) If peds are absent, chroma of 2 or more in 50

percent or more of the matrix; or

b. Hue of 10YR or yellower and either:

(1) Both a color value of 3 or more (moist) and

chroma of 3 or more; or

(2) Chroma of 2 or more if there are no redox

concentrations.

Udollic Epiaqualfs

JAJL. Other Epiaqualfs that have, in one or more horizons

between the A or Ap horizon and a depth of 75 cm below the

mineral soil surface, in 50 percent or more of the matrix, one or

a combination of the following colors:

1. Hue of 7.5YR or redder; and

a. If peds are present, chroma of 2 or more (both moist

and dry) on 50 percent or more of ped exteriors or no

redox depletions with chroma of 2 or less (both moist and

dry) in ped interiors; or

b. If peds are absent, chroma of 2 or more (both moist

and dry); or

2. Hue of 10YR or yellower and either:

a. Both a color value of 3 or more (moist) and chroma

of 3 or more (moist and dry); or

b. Chroma of 2 or more (both moist and dry) and no

redox concentrations.

Aeric Epiaqualfs

JAJM. Other Epiaqualfs that have a mollic epipedon, or the

upper 18 cm of the mineral soil meets all of the requirements

for a mollic epipedon, except for thickness, after mixing.

Mollic Epiaqualfs

JAJN. Other Epiaqualfs that have an umbric epipedon, or the

upper 18 cm of the mineral soil meets all of the requirements

for an umbric epipedon, except for thickness, after mixing.

Umbric Epiaqualfs

JAJO. Other Epiaqualfs.

Typic Epiaqualfs

Fragiaqualfs

Key to Subgroups

JAEA. Fragiaqualfs that have one or more layers, at least 25

cm thick (cumulative) within 100 cm of the mineral soil

surface, that have 25 percent or more (by volume) recognizable

bioturbation, such as filled animal burrows, wormholes, or casts.

Vermic Fragiaqualfs

JAEB. Other Fragiaqualfs that have, between the A or Ap

horizon and a fragipan, a horizon with 50 percent or more

chroma of 3 or more if hue is 10YR or redder or of 4 or more if

hue is 2.5Y or yellower.

Aeric Fragiaqualfs

JAEC. Other Fragiaqualfs that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Fragiaqualfs

JAED. Other Fragiaqualfs that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 18 cm of the mineral

soil or have materials between the soil surface and a depth of 18

cm that have these color values after mixing.

Humic Fragiaqualfs

JAEE. Other Fragiaqualfs.

Typic Fragiaqualfs

Glossaqualfs

Key to Subgroups

JAIA. Glossaqualfs that have a histic epipedon.

Histic Glossaqualfs

JAIB. Other Glossaqualfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 cm or more below the mineral soil surface.

Arenic Glossaqualfs
42 Keys to Soil Taxonomy

JAIC. Other Glossaqualfs that have:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. In one or more horizons between the A or Ap horizon

and a depth of 75 cm below the mineral soil surface, one or a

combination of the following colors:

a. Hue of 7.5YR or redder in 50 percent or more of the

matrix; and

(1) If peds are present, chroma of 2 or more on 50

percent or more of ped exteriors or no redox depletions

with chroma of 2 or less in ped interiors; or

(2) If peds are absent, chroma of 2 or more in 50

percent or more of the matrix; or

b. In 50 percent or more of the matrix, hue of 10YR or

yellower and either:

(1) Both a color value of 3 or more (moist) and

chroma of 3 or more (moist and dry); or

(2) Chroma of 2 or more if there are no redox

concentrations.

Aeric Fragic Glossaqualfs

JAID. Other Glossaqualfs that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Glossaqualfs

JAIE. Other Glossaqualfs that have, in one or more horizons

between the A or Ap horizon and a depth of 75 cm below the

mineral soil surface, in 50 percent or more of the matrix, one or

a combination of the following colors:

1. Hue of 7.5YR or redder; and

a. If peds are present, chroma of 2 or more (both moist

and dry) on 50 percent or more of ped exteriors or no

redox depletions with chroma of 2 or less (both moist and

dry) in ped interiors; or

b. If peds are absent, chroma of 2 or more (both moist

and dry); or

2. Hue of 10YR or yellower and either:

a. Both a color value of 3 or more (moist) and chroma

of 3 or more (moist and dry); or

b. Chroma of 2 or more (both moist and dry) and no

redox concentrations.

Aeric Glossaqualfs

JAIF. Other Glossaqualfs that have a mollic epipedon, or the

upper 18 cm of the mineral soil meets the requirements for a

mollic epipedon after mixing.

Mollic Glossaqualfs

JAIG. Other Glossaqualfs.

Typic Glossaqualfs

Kandiaqualfs

Key to Subgroups

JAFA. Kandiaqualfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a kandic horizon at a depth of

50 to 100 cm below the mineral soil surface.

Arenic Kandiaqualfs

JAFB. Other Kandiaqualfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a kandic horizon at a depth of

100 cm or more below the mineral soil surface.

Grossarenic Kandiaqualfs

JAFC. Other Kandiaqualfs that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kandiaqualfs

JAFD. Other Kandiaqualfs that have both:

1. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 18 cm of the mineral soil, or materials between the

soil surface and a depth of 18 cm have these color values

after mixing; and

2. In one or more horizons between the A or Ap horizon

and a depth of 75 cm below the mineral soil surface, in 50

percent or more of the matrix, one or a combination of the

following colors:

a. Hue of 7.5YR or redder; and

(1) If peds are present, chroma of 2 or more (both

moist and dry) on 50 percent or more of ped exteriors

or no redox depletions with chroma of 2 or less (both

moist and dry) in ped interiors; or

(2) If peds are absent, chroma of 2 or more (both

moist and dry); or
Alfisols 43

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L

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b. Hue of 10YR or yellower and either:

(1) Both a color value of 3 or more (moist) and

chroma of 3 or more (moist and dry); or

(2) Chroma of 2 or more (both moist and dry) and no

redox concentrations.

Aeric Umbric Kandiaqualfs

JAFE. Other Kandiaqualfs that have, in one or more horizons

between the A or Ap horizon and a depth of 75 cm below the

mineral soil surface, in 50 percent or more of the matrix, one or

a combination of the following colors:

1. Hue of 7.5YR or redder; and

a. If peds are present, chroma of 2 or more (both moist

and dry) on 50 percent or more of ped exteriors or no

redox depletions with chroma of 2 or less (both moist and

dry) in ped interiors; or

b. If peds are absent, chroma of 2 or more (both moist

and dry); or

2. Hue of 10YR or yellower and either:

a. Both a color value of 3 or more (moist) and chroma

of 3 or more (moist and dry); or

b. Chroma of 2 or more (both moist and dry) and no

redox concentrations.

Aeric Kandiaqualfs

JAFF. Other Kandiaqualfs that have an umbric epipedon, or

the upper 18 cm of the mineral soil meets the color

requirements for an umbric epipedon after mixing.

Umbric Kandiaqualfs

JAFG. Other Kandiaqualfs.

Typic Kandiaqualfs

Natraqualfs

Key to Subgroups

JADA. Natraqualfs that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Natraqualfs

JADB. Other Natraqualfs that have one or more layers, at

least 25 cm thick (cumulative) within 100 cm of the mineral soil

surface, that have 25 percent or more (by volume) recognizable

bioturbation, such as filled animal burrows, wormholes, or

casts.

Vermic Natraqualfs

JADC. Other Natraqualfs that have both:

1. A glossic horizon or interfingering of albic materials

into the natric horizon; and

2. An exchangeable sodium percentage of less than 15 and

less magnesium plus sodium than calcium plus extractable

acidity either throughout the upper 15 cm of the natric

horizon or in all horizons within 40 cm of the mineral soil

surface, whichever is deeper.

Albic Glossic Natraqualfs

JADD. Other Natraqualfs that have an exchangeable sodium

percentage of less than 15 and less magnesium plus sodium

than calcium plus extractable acidity either throughout the

upper 15 cm of the natric horizon or in all horizons within 40

cm of the mineral soil surface, whichever is deeper.

Albic Natraqualfs

JADE. Other Natraqualfs that have a glossic horizon

or interfingering of albic materials into the natric horizon.

Glossic Natraqualfs

JADF. Other Natraqualfs that have a mollic epipedon, or the

upper 18 cm of the mineral soil meets the color requirements

for a mollic epipedon after mixing.

Mollic Natraqualfs

JADG. Other Natraqualfs.

Typic Natraqualfs

Plinthaqualfs

Key to Subgroups

JABA. All Plinthaqualfs (provisionally).

Typic Plinthaqualfs

Vermaqualfs

Key to Subgroups

JAGA. Vermaqualfs that have an exchangeable sodium

percentage of 7 or more (or a sodium adsorption ratio of 6 or

more) either or both:

1. Throughout the upper 15 cm of the argillic horizon;

and/or

2. Throughout all horizons within 40 cm of the mineral soil

surface.

Natric Vermaqualfs
44 Keys to Soil Taxonomy

JAGB. Other Vermaqualfs.

Typic Vermaqualfs

Cryalfs

Key to Great Groups

JBA. Cryalfs that have all of the following:

1. An argillic, kandic, or natric horizon that has its upper

boundary 60 cm or more below both:

a. The mineral soil surface; and

b. The lower boundary of any surface mantle containing

30 percent or more vitric volcanic ash, cinders, or other

vitric pyroclastic materials; and

2. A texture (in the fine-earth fraction) finer than loamy

fine sand in one or more horizons above the argillic, kandic,

or natric horizon; and

3. Either a glossic horizon or interfingering of albic

materials into the argillic, kandic, or natric horizon.

Palecryalfs, p. 47

JBB. Other Cryalfs that have a glossic horizon.

Glossocryalfs, p. 44

JBC. Other Cryalfs.

Haplocryalfs, p. 45

Glossocryalfs

Key to Subgroups

JBBA. Glossocryalfs that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Glossocryalfs

JBBB. Other Glossocryalfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Glossocryalfs

JBBC. Other Glossocryalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Glossocryalfs

JBBD. Other Glossocryalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Glossocryalfs

JBBE. Other Glossocryalfs that have, in one or more

subhorizons within the upper 25 cm of the argillic, kandic, or

natric horizon, redox depletions with chroma of 2 or less

and also aquic conditions for some time in normal years

(or artificial drainage).

Aquic Glossocryalfs

JBBF. Other Glossocryalfs that are saturated with water in

one or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Glossocryalfs

JBBG. Other Glossocryalfs that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Glossocryalfs

JBBH. Other Glossocryalfs that have:

1. A xeric moisture regime; and

2. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 18 cm of the mineral soil, or materials between the

soil surface and a depth of 18 cm have these color values

after mixing; and
Alfisols 45

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L

F

3. A base saturation of 50 percent or more (by NH4OAc) in

all parts from the mineral soil surface to a depth of 180 cm

or to a densic, lithic, or paralithic contact, whichever is

shallower.

Xerollic Glossocryalfs

JBBI. Other Glossocryalfs that have:

1. A xeric moisture regime; and

2. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 18 cm of the mineral soil, or materials between the

soil surface and a depth of 18 cm have these color values

after mixing.

Umbric Xeric Glossocryalfs

JBBJ. Other Glossocryalfs that:

1. Are dry in some part of the moisture control section for

45 or more days (cumulative) in normal years; and

2. Have a color value, moist, of 3 or less and a color value,

dry, of 5 or less (crushed and smoothed sample) throughout

the upper 18 cm of the mineral soil or have materials

between the soil surface and a depth of 18 cm that have these

color values after mixing; and

3. Have a base saturation of 50 percent or more (by

NH4

OAc) in all parts from the mineral soil surface to a depth

of 180 cm or to a densic, lithic, or paralithic contact,

whichever is shallower.

Ustollic Glossocryalfs

JBBK. Other Glossocryalfs that have a xeric moisture regime.

Xeric Glossocryalfs

JBBL. Other Glossocryalfs that are dry in some part of the

moisture control section for 45 or more days (cumulative) in

normal years.

Ustic Glossocryalfs

JBBM. Other Glossocryalfs that:

1. Have a color value, moist, of 3 or less and a color value,

dry, of 5 or less (crushed and smoothed sample) throughout

the upper 18 cm of the mineral soil or have materials

between the soil surface and a depth of 18 cm that have these

color values after mixing; and

2. Have a base saturation of 50 percent or more (by

NH4

OAc) in all parts from the mineral soil surface to a depth

of 180 cm or to a densic, lithic, or paralithic contact,

whichever is shallower.

Mollic Glossocryalfs

JBBN. Other Glossocryalfs that have a color value, moist, of

3 or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 18 cm of the mineral

soil or have materials between the soil surface and a depth of 18

cm that have these color values after mixing.

Umbric Glossocryalfs

JBBO. Other Glossocryalfs that have a base saturation of 50

percent or more (by NH4

OAc) in all parts from the mineral soil

surface to a depth of 180 cm or to a densic, lithic, or paralithic

contact, whichever is shallower.

Eutric Glossocryalfs

JBBP. Other Glossocryalfs.

Typic Glossocryalfs

Haplocryalfs

Key to Subgroups

JBCA. Haplocryalfs that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haplocryalfs

JBCB. Other Haplocryalfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Haplocryalfs

JBCC. Other Haplocryalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haplocryalfs

JBCD. Other Haplocryalfs that have, throughout one or

more horizons with a total thickness of 18 cm or more

within 75 cm of the mineral soil surface, one or both of the

following:

1. More than 35 percent (by volume) fragments

coarser than 2.0 mm, of which more than 66 percent

is cinders, pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and
46 Keys to Soil Taxonomy

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Haplocryalfs

JBCE. Other Haplocryalfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Haplocryalfs

JBCF. Other Haplocryalfs that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplocryalfs

JBCG. Other Haplocryalfs that have an argillic horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more than

20 cm thick, each with an overlying eluvial horizon, and

above these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Haplocryalfs

JBCH. Other Haplocryalfs that have a sandy or sandy-skeletal

particle-size class throughout the upper 75 cm of the argillic,

kandic, or natric horizon or throughout the entire argillic,

kandic, or natric horizon if it is less than 75 cm thick.

Psammentic Haplocryalfs

JBCI. Other Haplocryalfs that have:

1. An argillic, kandic, or natric horizon that is 35 cm or

less thick; and

2. No densic, lithic, or paralithic contact within 100 cm of

the mineral soil surface.

Inceptic Haplocryalfs

JBCJ. Other Haplocryalfs that have:

1. A xeric moisture regime; and

2. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 18 cm of the mineral soil, or materials between the

soil surface and a depth of 18 cm have these color values

after mixing; and

3. A base saturation of 50 percent or more (by NH4

OAc) in

all parts from the mineral soil surface to a depth of 180 cm

or to a densic, lithic, or paralithic contact, whichever is

shallower.

Xerollic Haplocryalfs

JBCK. Other Haplocryalfs that have:

1. A xeric moisture regime; and

2. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 18 cm of the mineral soil, or materials between the

soil surface and a depth of 18 cm have these color values

after mixing.

Umbric Xeric Haplocryalfs

JBCL. Other Haplocryalfs that:

1. Are dry in some part of the moisture control section for

45 or more days (cumulative) in normal years; and

2. Have a color value, moist, of 3 or less and a color value,

dry, of 5 or less (crushed and smoothed sample) throughout

the upper 18 cm of the mineral soil or have materials

between the soil surface and a depth of 18 cm that have these

color values after mixing; and

3. Have a base saturation of 50 percent or more (by

NH4

OAc) in all parts from the mineral soil surface to a depth

of 180 cm or to a densic, lithic, or paralithic contact,

whichever is shallower.

Ustollic Haplocryalfs

JBCM. Other Haplocryalfs that have a xeric moisture regime.

Xeric Haplocryalfs

JBCN. Other Haplocryalfs that are dry in some part of the

moisture control section for 45 or more days (cumulative) in

normal years.

Ustic Haplocryalfs

JBCO. Other Haplocryalfs that:

1. Have a color value, moist, of 3 or less and a color value,

dry, of 5 or less (crushed and smoothed sample) throughout

the upper 18 cm of the mineral soil or have materials

between the soil surface and a depth of 18 cm that have these

color values after mixing; and
Alfisols 47

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L

F

2. Have a base saturation of 50 percent or more (by

NH4OAc) in all parts from the mineral soil surface to a depth

of 180 cm or to a densic, lithic, or paralithic contact,

whichever is shallower.

Mollic Haplocryalfs

JBCP. Other Haplocryalfs that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 18 cm of the mineral

soil or have materials between the soil surface and a depth of 18

cm that have these color values after mixing.

Umbric Haplocryalfs

JBCQ. Other Haplocryalfs that have a base saturation of 50

percent or more (by NH4

OAc) in all parts from the mineral soil

surface to a depth of 180 cm or to a densic, lithic, or paralithic

contact, whichever is shallower.

Eutric Haplocryalfs

JBCR. Other Haplocryalfs.

Typic Haplocryalfs

Palecryalfs

Key to Subgroups

JBAA. Palecryalfs that have, throughout one or more horizons

with a total thickness of 18 cm or more within 75 cm of the

mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Palecryalfs

JBAB. Other Palecryalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Palecryalfs

JBAC. Other Palecryalfs that have, in one or more horizons

within 100 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Palecryalfs

JBAD. Other Palecryalfs that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Palecryalfs

JBAE. Other Palecryalfs that have a xeric moisture regime.

Xeric Palecryalfs

JBAF. Other Palecryalfs that are dry in some part of the

moisture control section for 45 or more days (cumulative) in

normal years.

Ustic Palecryalfs

JBAG. Other Palecryalfs that:

1. Have a color value, moist, of 3 or less and a color value,

dry, of 5 or less (crushed and smoothed sample) throughout

the upper 18 cm of the mineral soil or have materials

between the soil surface and a depth of 18 cm that have these

color values after mixing; and

2. Have a base saturation of 50 percent or more (by

NH4

OAc) in all parts from the mineral soil surface to a depth

of 180 cm or to a densic, lithic, or paralithic contact,

whichever is shallower.

Mollic Palecryalfs

JBAH. Other Palecryalfs that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 18 cm of the mineral

soil or have materials between the soil surface and a depth of 18

cm that have these color values after mixing.

Umbric Palecryalfs

JBAI. Other Palecryalfs.

Typic Palecryalfs

Udalfs

Key to Great Groups

JEA. Udalfs that have a natric horizon.

Natrudalfs, p. 56

JEB. Other Udalfs that have:

1. A glossic horizon; and
48 Keys to Soil Taxonomy

2. In the argillic or kandic horizon, discrete nodules, 2.5 to

30 cm in diameter, that:

a. Are enriched with iron and extremely weakly

cemented to indurated; and

b. Have exteriors with either a redder hue or a higher

chroma than the interiors.

Ferrudalfs, p. 49

JEC. Other Udalfs that have both:

1. A glossic horizon; and

2. A fragipan with an upper boundary within 100 cm of the

mineral soil surface.

Fraglossudalfs, p. 49

JED. Other Udalfs that have a fragipan with an upper

boundary within 100 cm of the mineral soil surface.

Fragiudalfs, p. 49

JEE. Other Udalfs that:

1. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

2. Have a kandic horizon; and

3. Within 150 cm of the mineral soil surface, either:

a. Do not have a clay decrease with increasing depth of

20 percent or more (relative) from the maximum clay

content [Clay is measured noncarbonate clay or based on

the following formula: Clay % = 2.5(% water retained at

1500 kPa tension - % organic carbon), whichever value is

greater, but no more than 100]; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction.

Kandiudalfs, p. 55

JEF. Other Udalfs that have a kandic horizon.

Kanhapludalfs, p. 56

JEG. Other Udalfs that:

1. Do not have a densic, lithic, or paralithic contact within

150 cm of the mineral soil surface; and

2. Within 150 cm of the mineral soil surface, either:

a. Do not have a clay decrease with increasing depth of

20 percent or more (relative) from the maximum clay

content [Clay is measured noncarbonate clay or based on

the following formula: Clay % = 2.5(% water retained at

1500 kPa tension - % organic carbon), whichever value is

greater, but no more than 100]; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction; and

3. Have an argillic horizon with one or more of the

following:

a. In 50 percent or more of the matrix of one or more

subhorizons in its lower one-half, hue of 7.5YR or redder

and chroma of 5 or more; or

b. In 50 percent or more of the matrix of horizons that

total more than one-half the total thickness, hue of 2.5YR

or redder, value, moist, of 3 or less, and value, dry, of 4 or

less; or

c. Many coarse redox concentrations with hue of 5YR

or redder or chroma of 6 or more, or both, in one or more

subhorizons; or

4. Have a frigid temperature regime and all of the

following:

a. An argillic horizon that has its upper boundary 60 cm

or more below both:

(1) The mineral soil surface; and

(2) The lower boundary of any surface mantle

containing 30 percent or more vitric volcanic ash,

cinders, or other vitric pyroclastic materials; and

b. A texture (in the fine-earth fraction) finer than loamy

fine sand in one or more horizons above the argillic

horizon; and

c. Either a glossic horizon or interfingering of albic

materials into the argillic horizon.

Paleudalfs, p. 57

JEH. Other Udalfs that have, in all subhorizons in the upper

100 cm of the argillic horizon or throughout the entire argillic

horizon if less than 100 cm thick, more than 50 percent colors

that have all of the following:

1. Hue of 2.5YR or redder; and

2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist

value.

Rhodudalfs, p. 59

JEI. Other Udalfs that have a glossic horizon.

Glossudalfs, p. 50
Alfisols 49

A

L

F

JEJ. Other Udalfs.

Hapludalfs, p. 51

Ferrudalfs

Key to Subgroups

JEBA. Ferrudalfs that have, in one or more horizons within 60

cm of the mineral soil surface, redox depletions with chroma of

2 or less and also aquic conditions for some time in normal

years (or artificial drainage).

Aquic Ferrudalfs

JEBB. Other Ferrudalfs.

Typic Ferrudalfs

Fragiudalfs

Key to Subgroups

JEDA. Fragiudalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Fragiudalfs

JEDB. Other Fragiudalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Fragiudalfs

JEDC. Other Fragiudalfs that have, in one or more horizons

within 40 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Fragiudalfs

JEDD. Other Fragiudalfs that are saturated with water in one

or more layers above the fragipan in normal years for either or

both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Fragiudalfs

JEDE. Other Fragiudalfs.

Typic Fragiudalfs

Fraglossudalfs

Key to Subgroups

JECA. Fraglossudalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Fraglossudalfs

JECB. Other Fraglossudalfs that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Fraglossudalfs

JECC. Other Fraglossudalfs that have, in one or more

subhorizons within the upper 25 cm of the argillic or kandic

horizon, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Aquic Fraglossudalfs

JECD. Other Fraglossudalfs that are saturated with water in

one or more layers above the fragipan in normal years for either

or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Fraglossudalfs

JECE. Other Fraglossudalfs.

Typic Fraglossudalfs
50 Keys to Soil Taxonomy

Glossudalfs

Key to Subgroups

JEIA. Glossudalfs that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface.

Aquertic Glossudalfs

JEIB. Other Glossudalfs that have both:

1. Saturation with water in one or more layers within 100

cm of the mineral soil surface in normal years for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Oxyaquic Vertic Glossudalfs

JEIC. Other Glossudalfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Glossudalfs

JEID. Other Glossudalfs that have both:

1. In one or more subhorizons within the upper 25 cm of

the argillic horizon, redox depletions with chroma of 2 or

less and also aquic conditions for some time in normal years

(or artificial drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Glossudalfs

JEIE. Other Glossudalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Glossudalfs

JEIF. Other Glossudalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or
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2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Glossudalfs

JEIG. Other Glossudalfs that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface.

Fragiaquic Glossudalfs

JEIH. Other Glossudalfs that have both:

1. In one or more subhorizons within 75 cm of the mineral

soil surface, redox depletions with chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage); and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

the argillic horizon at a depth of 50 cm or more below the

mineral soil surface.

Aquic Arenic Glossudalfs

JEII. Other Glossudalfs that have, in one or more subhorizons

within the upper 25 cm of the argillic horizon, redox depletions

with chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Glossudalfs

JEIJ. Other Glossudalfs that have both:

1. Saturation with water in one or more layers within 100

cm of the mineral soil surface in normal years for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days; and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

the argillic horizon at a depth of 50 cm or more below the

mineral soil surface.

Arenic Oxyaquic Glossudalfs

JEIK. Other Glossudalfs that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Glossudalfs

JEIL. Other Glossudalfs that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Glossudalfs

JEIM. Other Glossudalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 cm or more below the mineral soil surface.

Arenic Glossudalfs

JEIN. Other Glossudalfs that have a glossic horizon less than

50 cm in total thickness.

Haplic Glossudalfs

JEIO. Other Glossudalfs.

Typic Glossudalfs

Hapludalfs

Key to Subgroups

JEJA. Hapludalfs that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Hapludalfs

JEJB. Other Hapludalfs that have all of the following:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick
52 Keys to Soil Taxonomy

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface; and

3. An Ap horizon or materials between the mineral soil

surface and a depth of 18 cm that, after mixing, have one or

more of the following:

a. A color value, moist, of 4 or more; or

b. A color value, dry, of 6 or more; or

c. Chroma of 4 or more.

Aquertic Chromic Hapludalfs

JEJC. Other Hapludalfs that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface.

Aquertic Hapludalfs

JEJD. Other Hapludalfs that have both:

1. Saturation with water in one or more layers within 100

cm of the mineral soil surface in normal years for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Oxyaquic Vertic Hapludalfs

JEJE. Other Hapludalfs that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. An Ap horizon or materials between the mineral soil

surface and a depth of 18 cm that, after mixing, have one or

more of the following:

a. A color value, moist, of 4 or more; or

b. A color value, dry, of 6 or more; or

c. Chroma of 4 or more.

Chromic Vertic Hapludalfs

JEJF. Other Hapludalfs that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or
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2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm or

a densic, lithic, or paralithic contact, whichever is shallower.

Vertic Hapludalfs

JEJG. Other Hapludalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Hapludalfs

JEJH. Other Hapludalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Hapludalfs

JEJI. Other Hapludalfs that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface.

Fragiaquic Hapludalfs

JEJJ. Other Hapludalfs that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. Saturation with water in one or more layers within 100

cm of the mineral soil surface in normal years for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Fragic Oxyaquic Hapludalfs

JEJK. Other Hapludalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A sandy or sandy-skeletal particle-size class

throughout a layer extending from the mineral soil surface to

the top of an argillic horizon at a depth of 50 cm or

more.

Aquic Arenic Hapludalfs

JEJL. Other Hapludalfs that have both:

1. Saturation with water in one or more layers within 100

cm of the mineral soil surface in normal years for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days; and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

the argillic horizon at a depth of 50 cm or more below the

mineral soil surface.

Arenic Oxyaquic Hapludalfs

JEJM. Other Hapludalfs that have anthraquic conditions.

Anthraquic Hapludalfs

JEJN. Other Hapludalfs that have:

1. An abrupt textural change; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or
54 Keys to Soil Taxonomy

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface; and

3. A base saturation (by sum of cations) of less than 60

percent at a depth of 125 cm from the top of the argillic

horizon, at a depth of 180 cm from the mineral soil surface,

or directly above a densic, lithic, or paralithic contact,

whichever is shallowest.

Albaquultic Hapludalfs

JEJO. Other Hapludalfs that have both:

1. An abrupt textural change; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface.

Albaquic Hapludalfs

JEJP. Other Hapludalfs that have both:

1. Interfingering of albic materials in the upper part of the

argillic horizon; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface.

Glossaquic Hapludalfs

JEJQ. Other Hapludalfs that have both:

1. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface; and

2. A base saturation (by sum of cations) of less than 60

percent at a depth of 125 cm from the top of the argillic

horizon, at a depth of 180 cm from the mineral soil surface,

or directly above a densic, lithic, or paralithic contact,

whichever is shallowest.

Aquultic Hapludalfs

JEJR. Other Hapludalfs that have both:

1. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 18 cm of the mineral soil, or materials between the

soil surface and a depth of 18 cm have these color values

after mixing; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface.

Aquollic Hapludalfs

JEJS. Other Hapludalfs that have redox depletions with

chroma of 2 or less in layers that also have aquic conditions in

normal years (or artificial drainage) either:

1. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil surface; or

2. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below the

mineral soil surface.

Aquic Hapludalfs

JEJT. Other Hapludalfs that have both:

1. A mollic epipedon, or the upper 18 cm of the mineral

soil meets the color requirements for a mollic epipedon after

mixing; and

2. Saturation with water in 1 or more layers within 100 cm

of the mineral soil surface in normal years for either or both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Mollic Oxyaquic Hapludalfs

JEJU. Other Hapludalfs that are saturated with water in one or

more layers within 100 cm of the mineral soil surface in normal

years for either or both:

1. 20 or more consecutive days; or
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2. 30 or more cumulative days.

Oxyaquic Hapludalfs

JEJV. Other Hapludalfs that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Hapludalfs

JEJW. Other Hapludalfs that have an argillic horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more than

20 cm thick, each with an overlying eluvial horizon, and

above these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Hapludalfs

JEJX. Other Hapludalfs that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or

throughout the entire argillic horizon if it is less than 75 cm

thick.

Psammentic Hapludalfs

JEJY. Other Hapludalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 cm or more.

Arenic Hapludalfs

JEJZ. Other Hapludalfs that have interfingering of albic

materials in one or more subhorizons of the argillic horizon.

Glossic Hapludalfs

JEJZa. Other Hapludalfs that have:

1. An argillic, kandic, or natric horizon that is 35 cm or

less thick; and

2. No densic, lithic, or paralithic contact within 100 cm of

the mineral soil surface.

Inceptic Hapludalfs

JEJZb. Other Hapludalfs that have a base saturation (by sum

of cations) of less than 60 percent at a depth of 125 cm below

the top of the argillic horizon, at a depth of 180 cm below the

mineral soil surface, or directly above a densic, lithic, or

paralithic contact, whichever is shallowest.

Ultic Hapludalfs

JEJZc. Other Hapludalfs that have a mollic epipedon, or the

upper 18 cm of the mineral soil meets all the color requirements

for a mollic epipedon after mixing.

Mollic Hapludalfs

JEJZd. Other Hapludalfs.

Typic Hapludalfs

Kandiudalfs

Key to Subgroups

JEEA. Kandiudalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Plinthaquic Kandiudalfs

JEEB. Other Kandiudalfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Kandiudalfs

JEEC. Other Kandiudalfs that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Kandiudalfs

JEED. Other Kandiudalfs that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 50 to 100 cm; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Arenic Plinthic Kandiudalfs

JEEE. Other Kandiudalfs that have both:

1. A sandy or sandy-skeletal particle-size class throughout
56 Keys to Soil Taxonomy

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 100 cm or more; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Grossarenic Plinthic Kandiudalfs

JEEF. Other Kandiudalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a kandic horizon at a depth of

50 to 100 cm.

Arenic Kandiudalfs

JEEG. Other Kandiudalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a kandic horizon at a depth of

100 cm or more.

Grossarenic Kandiudalfs

JEEH. Other Kandiudalfs that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kandiudalfs

JEEI. Other Kandiudalfs that have, in all subhorizons in the

upper 100 cm of the kandic horizon or throughout the entire

kandic horizon if less than 100 cm thick, more than 50 percent

colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist

value.

Rhodic Kandiudalfs

JEEJ. Other Kandiudalfs that have a mollic epipedon, or the

upper 18 cm of the mineral soil meets the color requirements

for a mollic epipedon after mixing.

Mollic Kandiudalfs

JEEK. Other Kandiudalfs.

Typic Kandiudalfs

Kanhapludalfs

Key to Subgroups

JEFA. Kanhapludalfs that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Kanhapludalfs

JEFB. Other Kanhapludalfs that have, in one or

more horizons within 75 cm of the mineral soil surface,

redox depletions with chroma of 2 or less and also aquic

conditions for some time in normal years (or artificial

drainage).

Aquic Kanhapludalfs

JEFC. Other Kanhapludalfs that are saturated with water in

one or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Kanhapludalfs

JEFD. Other Kanhapludalfs that have, in all subhorizons in

the upper 100 cm of the kandic horizon or throughout the entire

kandic horizon if less than 100 cm thick, more than 50 percent

colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist

value.

Rhodic Kanhapludalfs

JEFE. Other Kanhapludalfs.

Typic Kanhapludalfs

Natrudalfs

Key to Subgroups

JEAA. Natrudalfs that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Natrudalfs

JEAB. Other Natrudalfs that have:

1. Either a glossic horizon or interfingering of albic

materials into the natric horizon; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the natric horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or
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b. Within 75 cm of the mineral soil surface if the upper

boundary of the natric horizon is 50 cm or more below

the mineral soil surface.

Glossaquic Natrudalfs

JEAC. Other Natrudalfs that have redox depletions with

chroma of 2 or less in layers that also have aquic conditions in

normal years (or artificial drainage) either:

1. Within the upper 25 cm of the natric horizon if its upper

boundary is within 50 cm of the mineral soil surface; or

2. Within 75 cm of the mineral soil surface if the upper

boundary of the natric horizon is 50 cm or more below the

mineral soil surface.

Aquic Natrudalfs

JEAD. Other Natrudalfs.

Typic Natrudalfs

Paleudalfs

Key to Subgroups

JEGA. Paleudalfs that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Paleudalfs

JEGB. Other Paleudalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Paleudalfs

JEGC. Other Paleudalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Paleudalfs

JEGD. Other Paleudalfs that have anthraquic conditions.

Anthraquic Paleudalfs

JEGE. Other Paleudalfs that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic horizon if its

upper boundary is within 50 cm of the mineral soil

surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic horizon is 50 cm or more below

the mineral soil surface.

Fragiaquic Paleudalfs

JEGF. Other Paleudalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Plinthaquic Paleudalfs

JEGG. Other Paleudalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A glossic horizon or, in the upper part of the argillic

horizon, one or more subhorizons that have 5 percent

or more (by volume) clay depletions with chroma of 2

or less.

Glossaquic Paleudalfs

JEGH. Other Paleudalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also
58 Keys to Soil Taxonomy

aquic conditions for some time in normal years (or artificial

drainage); and

2. A clay increase of 15 percent or more (absolute) in the

fine-earth fraction within a vertical distance of 2.5 cm at the

upper boundary of the argillic horizon.

Albaquic Paleudalfs

JEGI. Other Paleudalfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Paleudalfs

JEGJ. Other Paleudalfs that are saturated with water in one or

more layers within 100 cm of the mineral soil surface in normal

years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Paleudalfs

JEGK. Other Paleudalfs that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Paleudalfs

JEGL. Other Paleudalfs that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 to 100 cm; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Arenic Plinthic Paleudalfs

JEGM. Other Paleudalfs that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 100 cm or more; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Grossarenic Plinthic Paleudalfs

JEGN. Other Paleudalfs that have an argillic horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more than

20 cm thick, each with an overlying eluvial horizon, and

above these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Paleudalfs

JEGO. Other Paleudalfs that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or hroughout

the entire argillic horizon if it is less than 75 cm thick.

Psammentic Paleudalfs

JEGP. Other Paleudalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm.

Arenic Paleudalfs

JEGQ. Other Paleudalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 100 cm or more.

Grossarenic Paleudalfs

JEGR. Other Paleudalfs that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Paleudalfs

JEGS. Other Paleudalfs that have either:

1. A glossic horizon; or

2. In the upper part of the argillic horizon, one or more

subhorizons that have 5 percent or more (by volume)

skeletans with chroma of 2 or less; or

3. 5 percent or more (by volume) albic materials in some

subhorizon of the argillic horizon.

Glossic Paleudalfs

JEGT. Other Paleudalfs that have, in all subhorizons in the

upper 100 cm of the argillic horizon or throughout the entire

argillic horizon if less than 100 cm thick, more than 50 percent

colors that have all of the following:

1. Hue of 2.5YR or redder; and
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2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist value.

Rhodic Paleudalfs

JEGU. Other Paleudalfs that have a mollic epipedon, or the

upper 18 cm of the mineral soil meets the color requirements

for a mollic epipedon after mixing.

Mollic Paleudalfs

JEGV. Other Paleudalfs.

Typic Paleudalfs

Rhodudalfs

Key to Subgroups

JEHA. All Rhodudalfs (provisionally).

Typic Rhodudalfs

Ustalfs

Key to Great Groups

JCA. Ustalfs that have a duripan that has its upper boundary

within 100 cm of the mineral soil surface.

Durustalfs, p. 60

JCB. Other Ustalfs that have one or more horizons within 150

cm of the mineral soil surface in which plinthite either forms a

continuous phase or constitutes one-half or more of the volume.

Plinthustalfs, p. 70

JCC. Other Ustalfs that have a natric horizon.

Natrustalfs, p. 65

JCD. Other Ustalfs that:

1. Have a kandic horizon; and

2. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

3. Within 150 cm of the mineral soil surface, either:

a. Do not have a clay decrease with increasing depth of

20 percent or more (relative) from the maximum clay

content [Clay is measured noncarbonate clay or based on

the following formula: Clay % = 2.5(% water retained at

1500 kPa tension - % organic carbon), whichever value is

greater, but no more than 100]; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction.

Kandiustalfs, p. 63

JCE. Other Ustalfs that have a kandic horizon.

Kanhaplustalfs, p. 64

JCF. Other Ustalfs that have one or more of the following:

1. A petrocalcic horizon that has its upper boundary within

150 cm of the mineral soil surface; or

2. No densic, lithic, or paralithic contact within 150 cm of

the mineral soil surface and an argillic horizon that has both:

a. Within 150 cm of the mineral soil surface, either:

(1) With increasing depth, no clay decrease of 20

percent or more (relative) from the maximum clay

content [Clay is measured noncarbonate clay or based

on the following formula: Clay % = 2.5(% water

retained at 1500 kPa tension - % organic carbon),

whichever value is greater, but no more than 100]; or

(2) 5 percent or more (by volume) skeletans on faces

of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3

percent or more (absolute) in the fine-earth fraction; and

b. In the lower one-half of the argillic horizon, one or

more subhorizons with either or both:

(1) Hue of 7.5YR or redder and chroma of 5 or more

in 50 percent or more of the matrix; or

(2) Common or many coarse redox concentrations

with hue of 7.5YR or redder or chroma of 6 or more,

or both; or

3. No densic, lithic, or paralithic contact within 50 cm of

the mineral soil surface and an argillic horizon that has both:

a. A clayey or clayey-skeletal particle-size class

throughout one or more subhorizons in its upper part; and

b. At its upper boundary, a clay increase (in the fineearth fraction) of either 20 percent or more (absolute)

within a vertical distance of 7.5 cm or of 15 percent or

more (absolute) within a vertical distance of 2.5 cm.

Paleustalfs, p. 67

JCG. Other Ustalfs that have, in all subhorizons in the upper

100 cm of the argillic horizon or throughout the entire argillic

horizon if less than 100 cm thick, more than 50 percent colors

that have all of the following:

1. Hue of 2.5YR or redder; and

2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist

value.

Rhodustalfs, p. 70

JCH. Other Ustalfs.

Haplustalfs, p. 60
60 Keys to Soil Taxonomy

Durustalfs

Key to Subgroups

JCAA. All Durustalfs (provisionally).

Typic Durustalfs

Haplustalfs

Key to Subgroups

JCHA. Haplustalfs that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haplustalfs

JCHB. Other Haplustalfs that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Aquertic Haplustalfs

JCHC. Other Haplustalfs that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. Saturation with water in one or more layers within 100

cm of the mineral soil surface in normal years for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Oxyaquic Vertic Haplustalfs

JCHD. Other Haplustalfs that have both of the following:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC;

2. One or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or

b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Torrertic Haplustalfs

JCHE. Other Haplustalfs that have both:

1. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for four-tenths or less of the cumulative days

per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 o

C; or

b. A hyperthermic, isomesic, or warmer iso soil
Alfisols 61

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temperature regime and a moisture control section that in

normal years is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth

of 50 cm below the soil surface is higher than 8 oC; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Udertic Haplustalfs

JCHF. Other Haplustalfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Haplustalfs

JCHG. Other Haplustalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 to 100 cm.

Aquic Arenic Haplustalfs

JCHH. Other Haplustalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. An argillic horizon that has a base saturation (by sum of

cations) of less than 75 percent throughout.

Aquultic Haplustalfs

JCHI. Other Haplustalfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Haplustalfs

JCHJ. Other Haplustalfs that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplustalfs

JCHK. Other Haplustalfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Haplustalfs

JCHL. Other Haplustalfs that have an argillic horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more than

20 cm thick, each with an overlying eluvial horizon, and

above these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Haplustalfs

JCHM. Other Haplustalfs that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or

throughout the entire argillic horizon if it is less than 75 cm

thick.

Psammentic Haplustalfs
62 Keys to Soil Taxonomy

JCHN. Other Haplustalfs that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 cm or more; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

b. A mesic or thermic soil temperature regime

and a moisture control section that in normal years

is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature

at a depth of 50 cm below the soil surface is higher

than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Arenic Aridic Haplustalfs

JCHO. Other Haplustalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 cm or more.

Arenic Haplustalfs

JCHP. Other Haplustalfs that have both:

1. A calcic horizon with its upper boundary within 100 cm

of the mineral soil surface; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Calcidic Haplustalfs

JCHQ. Other Haplustalfs that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Haplustalfs

JCHR. Other Haplustalfs that have a CEC of less than 24

cmol(+)/kg clay (by 1N NH4

OAc pH 7) in 50 percent or more

either of the argillic horizon if less than 100 cm thick or of its

upper 100 cm.

Kanhaplic Haplustalfs

JCHS. Other Haplustalfs that have:

1. An argillic, kandic, or natric horizon that is 35 cm or

less thick; and
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2. No densic, lithic, or paralithic contact within 100 cm of

the mineral soil surface.

Inceptic Haplustalfs

JCHT. Other Haplustalfs that have both:

1. A calcic horizon with its upper boundary within 100 cm

of the mineral soil surface; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in some or all parts for

less than 105 cumulative days per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for four-tenths or less of the cumulative days

per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth

of 50 cm below the soil surface is higher than 8 oC.

Calcic Udic Haplustalfs

JCHU. Other Haplustalfs that have an argillic horizon with a

base saturation (by sum of cations) of less than 75 percent

throughout.

Ultic Haplustalfs

JCHV. Other Haplustalfs that have a calcic horizon with its

upper boundary within 100 cm of the mineral soil surface.

Calcic Haplustalfs

JCHW. Other Haplustalfs that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in some or all parts for

less than 105 cumulative days per year when the temperature

at a depth of 50 cm below the soil surface is higher than 5

o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for four-tenths or less of the cumulative days per year

when the temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Udic Haplustalfs

JCHX. Other Haplustalfs.

Typic Haplustalfs

Kandiustalfs

Key to Subgroups

JCDA. Kandiustalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a kandic horizon at a depth of

100 cm or more.

Grossarenic Kandiustalfs

JCDB. Other Kandiustalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 50 to 100 cm.

Aquic Arenic Kandiustalfs

JCDC. Other Kandiustalfs that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kandiustalfs

JCDD. Other Kandiustalfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Kandiustalfs

JCDE. Other Kandiustalfs that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 50 to 100 cm; and

2. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 o

C; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:
64 Keys to Soil Taxonomy

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Arenic Aridic Kandiustalfs

JCDF. Other Kandiustalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a kandic horizon at a depth of

50 to 100 cm.

Arenic Kandiustalfs

JCDG. Other Kandiustalfs that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Kandiustalfs

JCDH. Other Kandiustalfs that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for 135 cumulative days or less per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 o

C.

Udic Kandiustalfs

JCDI. Other Kandiustalfs that have, in all subhorizons in the

upper 100 cm of the kandic horizon or throughout the entire

kandic horizon if less than 100 cm thick, more than 50 percent

colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist

value.

Rhodic Kandiustalfs

JCDJ. Other Kandiustalfs.

Typic Kandiustalfs

Kanhaplustalfs

Key to Subgroups

JCEA. Kanhaplustalfs that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Kanhaplustalfs

JCEB. Other Kanhaplustalfs that have, in one or more

horizons within 75 cm of the mineral soil surface, redox

depletions with chroma of 2 or less and also aquic conditions

for some time in normal years (or artificial drainage).

Aquic Kanhaplustalfs

JCEC. Other Kanhaplustalfs that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than5 oC.

Aridic Kanhaplustalfs

JCED. Other Kanhaplustalfs that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a
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moisture control section that in normal years is dry in some

part for 135 cumulative days or less per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Udic Kanhaplustalfs

JCEE. Other Kanhaplustalfs that have, in all subhorizons in

the upper 100 cm of the kandic horizon or throughout the entire

kandic horizon if less than 100 cm thick, more than 50 percent

colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist

value.

Rhodic Kanhaplustalfs

JCEF. Other Kanhaplustalfs.

Typic Kanhaplustalfs

Natrustalfs

Key to Subgroups

JCCA. Natrustalfs that have a salic horizon that has its upper

boundary within 75 cm of the mineral soil surface.

Salidic Natrustalfs

JCCB. Other Natrustalfs that have all of the following:

1. Visible crystals of gypsum or other salts more soluble

than gypsum, or both, within 40 cm of the soil surface; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 o

C; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 o

C; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC; and

3. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Leptic Torrertic Natrustalfs

JCCC. Other Natrustalfs that have both of the following:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or
66 Keys to Soil Taxonomy

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Torrertic Natrustalfs

JCCD. Other Natrustalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Aquertic Natrustalfs

JCCE. Other Natrustalfs that have both of the following:

1. Visible crystals of gypsum or other salts more soluble

than gypsum, or both, within 40 cm of the mineral soil

surface; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 o

C; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Leptic Natrustalfs

JCCF. Other Natrustalfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm or

a densic, lithic, or paralithic contact, whichever is shallower.

Vertic Natrustalfs

JCCG. Other Natrustalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 cm or more.

Aquic Arenic Natrustalfs

JCCH. Other Natrustalfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Natrustalfs

JCCI. Other Natrustalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 cm or more.

Arenic Natrustalfs

JCCJ. Other Natrustalfs that have a petrocalcic horizon that

has its upper boundary within 150 cm of the mineral soil surface.

Petrocalcic Natrustalfs

JCCK. Other Natrustalfs that have visible crystals of gypsum

or other salts more soluble than gypsum, or both, within 40 cm

of the mineral soil surface.

Leptic Natrustalfs
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JCCL. Other Natrustalfs that have both of the following:

1. An exchangeable sodium percentage of less than 15 (or

a sodium adsorption ratio of less than 13) in 50 percent or

more of the natric horizon; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Haplargidic Natrustalfs

JCCM. Other Natrustalfs that have both:

1. When neither irrigated nor fallowed to store moisture, one

of the following:

a. A frigid soil temperature regime and a moisture

control section that in normal years is dry in all parts for

four-tenths or more of the cumulative days per year when

the temperature at a depth of 50 cm below the soil surface

is higher than 5 °C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that, in 6 normal years, is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 °C; or

c. A hyperthermic, an isomesic, or a warmer iso soil

temperature regime and a moisture control section that, in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 °C;

and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the temperature at a depth

of 50 cm below the soil surface is higher than 5 °C; and

2. A glossic horizon or interfingering of albic materials

into the natric horizon.

Aridic Glossic Natrustalfs

JCCN. Other Natrustalfs that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 5 oC.

Aridic Natrustalfs

JCCO. Other Natrustalfs that have a mollic epipedon, or the

upper 18 cm of the mineral soil meets the color requirements

for a mollic epipedon after mixing.

Mollic Natrustalfs

JCCP. Other Natrustalfs.

Typic Natrustalfs

Paleustalfs

Key to Subgroups

JCFA. Paleustalfs that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or
68 Keys to Soil Taxonomy

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Aquertic Paleustalfs

JCFB. Other Paleustalfs that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. Saturation with water in one or more layers within 100

cm of the mineral soil surface in normal years for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Oxyaquic Vertic Paleustalfs

JCFC. Other Paleustalfs that have both:

1. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for four-tenths or less of the time (cumulative)

per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 o

C; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth

of 50 cm below the soil surface is higher than 8 oC; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Udertic Paleustalfs

JCFD. Other Paleustalfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Paleustalfs

JCFE. Other Paleustalfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 to 100 cm.

Aquic Arenic Paleustalfs

JCFF. Other Paleustalfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Paleustalfs

JCFG. Other Paleustalfs that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Paleustalfs

JCFH. Other Paleustalfs that have an argillic horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or
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3. Consists of one or more subhorizons that are more than

20 cm thick, each with an overlying eluvial horizon, and

above these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Paleustalfs

JCFI. Other Paleustalfs that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or

throughout the entire argillic horizon if it is less than 75 cm

thick.

Psammentic Paleustalfs

JCFJ. Other Paleustalfs that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 to 100 cm; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the time (cumulative) per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the time (cumulative)

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Arenic Aridic Paleustalfs

JCFK. Other Paleustalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 100 cm or more.

Grossarenic Paleustalfs

JCFL. Other Paleustalfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm.

Arenic Paleustalfs

JCFM. Other Paleustalfs that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Paleustalfs

JCFN. Other Paleustalfs that have a petrocalcic horizon that

has its upper boundary within 150 cm of the mineral soil

surface.

Petrocalcic Paleustalfs

JCFO. Other Paleustalfs that have both:

1. When neither irrigated nor fallowed to store moisture,

either:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the time (cumulative) per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the time (cumulative)

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC; and

2. A calcic horizon either within 100 cm of the mineral soil

surface if the weighted average particle-size class of the

upper 50 cm of the argillic horizon is sandy, or within 60 cm

if it is loamy, or within 50 cm if it is clayey, and carbonates

in all horizons above the calcic horizon.

Calcidic Paleustalfs
70 Keys to Soil Taxonomy

JCFP. Other Paleustalfs that, when neither irrigated nor

fallowed to store moisture, have:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the time (cumulative) per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for six-tenths or more of the time (cumulative) per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for less than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Paleustalfs

JCFQ. Other Paleustalfs that have a CEC of less than 24

cmol(+)/kg clay (by 1N NH4OAc pH 7) in 50 percent or more

either of the argillic horizon if less than 100 cm thick or of its

upper 100 cm.

Kandic Paleustalfs

JCFR. Other Paleustalfs that have, in all subhorizons in the

upper 100 cm of the argillic horizon or throughout the entire

argillic horizon if less than 100 cm thick, more than 50 percent

colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist

value.

Rhodic Paleustalfs

JCFS. Other Paleustalfs that have an argillic horizon with a

base saturation (by sum of cations) of less than 75 percent

throughout.

Ultic Paleustalfs

JCFT. Other Paleustalfs that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for four-tenths or less of the time (cumulative) per year

when the temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Udic Paleustalfs

JCFU. Other Paleustalfs.

Typic Paleustalfs

Plinthustalfs

Key to Subgroups

JCBA. All Plinthustalfs (provisionally).

Typic Plinthustalfs

Rhodustalfs

Key to Subgroups

JCGA. Rhodustalfs that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Rhodustalfs

JCGB. Other Rhodustalfs that have a CEC of less than 24

cmol(+)/kg clay (by 1N NH4

OAc pH 7) in 50 percent or more

either of the argillic horizon if less than 100 cm thick or of its

upper 100 cm.

Kanhaplic Rhodustalfs

JCGC. Other Rhodustalfs that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for four-tenths or less of the time (cumulative) per year

when the temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 o

C.

Udic Rhodustalfs

JCGD. Other Rhodustalfs.

Typic Rhodustalfs
Alfisols 71

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Xeralfs

Key to Great Groups

JDA. Xeralfs that have a duripan that has its upper boundary

within 100 cm of the mineral soil surface.

Durixeralfs, p. 71

JDB. Other Xeralfs that have a natric horizon.

Natrixeralfs, p. 74

JDC. Other Xeralfs that have a fragipan with an upper

boundary within 100 cm of the mineral soil surface.

Fragixeralfs, p. 72

JDD. Other Xeralfs that have one or more horizons within

150 cm of the mineral soil surface in which plinthite either

forms a continuous phase or constitutes one-half or more of the

volume.

Plinthoxeralfs, p. 76

JDE. Other Xeralfs that have, in all subhorizons in the upper

100 cm of the argillic or kandic horizon or throughout the entire

argillic or kandic horizon if less than 100 cm thick, more than

50 percent colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. Value, moist, of 3 or less; and

3. Dry value no more than 1 unit higher than the moist

value.

Rhodoxeralfs, p. 76

JDF. Other Xeralfs that have one or more of the following:

1. A petrocalcic horizon that has its upper boundary within

150 cm of the mineral soil surface; or

2. No densic, lithic, or paralithic contact within 150 cm of

the mineral soil surface and an argillic or kandic horizon that

has both:

a. Within 150 cm of the mineral soil surface, either:

(1) With increasing depth, no clay decrease of 20

percent or more (relative) from the maximum clay

content [Clay is measured noncarbonate clay or based

on the following formula: Clay % = 2.5(% water

retained at 1500 kPa tension - % organic carbon),

whichever value is greater, but no more than 100]; or

(2) 5 percent or more (by volume) skeletans on faces

of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3

percent or more (absolute) in the fine-earth fraction;

and

b. A base at a depth of 150 cm or mre; or

3. No densic, lithic, or paralithic contact within 50 cm of

the mineral soil surface and an argillic or kandic horizon that

has within 15 cm of its upper boundary both:

a. A clayey, clayey-skeletal, fine, or very-fine particlesize class; and

b. A clay increase, in the fine-earth fraction, of either 20

percent or more (absolute) within a vertical distance of

7.5 cm or of 15 percent or more (absolute) within a

vertical distance of 2.5 cm.

Palexeralfs, p. 74

JDG. Other Xeralfs.

Haploxeralfs, p. 72

Durixeralfs

Key to Subgroups

JDAA. Durixeralfs that have a natric horizon.

Natric Durixeralfs

JDAB. Other Durixeralfs that have, above the duripan, one or

both of the following:

1. Cracks that are 5 mm or more wide through a thickness

of 30 cm or more for some time in normal years and

slickensides or wedge-shaped aggregates in a layer 15 cm or

more thick; or

2. A linear extensibility of 6.0 cm or more.

Vertic Durixeralfs

JDAC. Other Durixeralfs that have, in one or more

subhorizons within the argillic horizon, redox depletions with

croma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Durixeralfs

JDAD. Other Durixeralfs that have both:

1. An argillic horizon that has both:

a. A clayey particle-size class throughout some

subhorizon 7.5 cm or more thick; and

b. At its upper boundary or within some part, a clay

increase either of 20 percent or more (absolute) within a

vertical distance of 7.5 cm or of 15 percent or more

(absolute) within a vertical distance of 2.5 cm, in the fineearth fraction; and

2. A duripan that is strongly cemented or less cemented in

all subhorizons.

Abruptic Haplic Durixeralfs
72 Keys to Soil Taxonomy

JDAE. Other Durixeralfs that have an argillic horizon that has

both:

1. A clayey particle-size class throughout some subhorizon

7.5 cm or more thick; and

2. At its upper boundary or within some part, a clay

increase either of 20 percent or more (absolute) within a

vertical distance of 7.5 cm or of 15 percent or more

(absolute) within a vertical distance of 2.5 cm, in the fineearth fraction.

Abruptic Durixeralfs

JDAF. Other Durixeralfs that have a duripan that is strongly

cemented or less cemented in all subhorizons.

Haplic Durixeralfs

JDAG. Other Durixeralfs.

Typic Durixeralfs

Fragixeralfs

Key to Subgroups

JDCA. Fragixeralfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Fragixeralfs

JDCB. Other Fragixeralfs that have, throughout one or

more horizons with a total thickness of 18 cm or more

within 75 cm of the mineral soil surface, one or both of the

following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Fragixeralfs

JDCC. Other Fragixeralfs that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 18 cm of the mineral

soil or have materials between the soil surface and a depth of 18

cm that have these color values after mixing.

Mollic Fragixeralfs

JDCD. Other Fragixeralfs that have, in one or more horizons

within 40 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Fragixeralfs

JDCE. Other Fragixeralfs that, above the fragipan, do not

have an argillic or kandic horizon with clay films on both

vertical and horizontal faces of any peds.

Inceptic Fragixeralfs

JDCF. Other Fragixeralfs.

Typic Fragixeralfs

Haploxeralfs

Key to Subgroups

JDGA. Haploxeralfs that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. A color value, moist, of 3 or less and 0.7 percent or

more organic carbon either throughout an Ap horizon or

throughout the upper 10 cm of an A horizon.

Lithic Mollic Haploxeralfs

JDGB. Other Haploxeralfs that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. An argillic or kandic horizon that is discontinuous

horizontally in each pedon.

Lithic Ruptic-Inceptic Haploxeralfs

JDGC. Other Haploxeralfs that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Haploxeralfs

JDGD. Other Haploxeralfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Haploxeralfs

JDGE. Other Haploxeralfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also
Alfisols 73

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F

aquic conditions for some time in normal years (or artificial

drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Haploxeralfs

JDGF. Other Haploxeralfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haploxeralfs

JDGG. Other Haploxeralfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Haploxeralfs

JDGH. Other Haploxeralfs that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic or kandic

horizon if its upper boundary is within 50 cm of the

mineral soil surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic or kandic horizon is 50 cm or

more below the mineral soil surface.

Fragiaquic Haploxeralfs

JDGI. Other Haploxeralfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. An argillic or kandic horizon that has a base saturation

(by sum of cations) of less than 75 percent in one or more

subhorizons within its upper 75 cm or above a densic, lithic,

or paralithic contact, whichever is shallower.

Aquultic Haploxeralfs

JDGJ. Other Haploxeralfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Haploxeralfs

JDGK. Other Haploxeralfs that have an exchangeable sodium

percentage of 15 or more (or a sodium adsorption ratio of 13 or

more) in one or more subhorizons of the argillic or kandic

horizon.

Natric Haploxeralfs

JDGL. Other Haploxeralfs that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Haploxeralfs

JDGM. Other Haploxeralfs that have an argillic horizon that:

1. Consists entirely of lamellae; or
74 Keys to Soil Taxonomy

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more than

20 cm thick, each with an overlying eluvial horizon, and

above these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Haploxeralfs

JDGN. Other Haploxeralfs that have a sandy particle-size

class throughout the upper 75 cm of the argillic horizon or

throughout the entire argillic horizon if it is less than 75 cm

thick.

Psammentic Haploxeralfs

JDGO. Other Haploxeralfs that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Haploxeralfs

JDGP. Other Haploxeralfs that have a calcic horizon that has

its upper boundary within 100 cm of the mineral soil surface.

Calcic Haploxeralfs

JDGQ. Other Haploxeralfs that have:

1. An argillic, kandic, or natric horizon that is 35 cm or

less thick; and

2. No densic, lithic, or paralithic contact within 100 cm of

the mineral soil surface.

Inceptic Haploxeralfs

JDGR. Other Haploxeralfs that have an argillic or kandic

horizon that has a base saturation (by sum of cations) of less

than 75 percent in one or more subhorizons within its upper 75

cm or above a densic, lithic, or paralithic contact, whichever is

shallower.

Ultic Haploxeralfs

JDGS. Other Haploxeralfs that have a color value, moist, of

3 or less and 0.7 percent or more organic carbon either

throughout the upper 10 cm of the mineral soil (unmixed) or

throughout the upper 18 cm of the mineral soil after mixing.

Mollic Haploxeralfs

JDGT. Other Haploxeralfs.

Typic Haploxeralfs

Natrixeralfs

Key to Subgroups

JDBA. Natrixeralfs that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Natrixeralfs

JDBB. Other Natrixeralfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Natrixeralfs

JDBC. Other Natrixeralfs.

Typic Natrixeralfs

Palexeralfs

Key to Subgroups

JDFA. Palexeralfs that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Palexeralfs

JDFB. Other Palexeralfs that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or
Alfisols 75

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F

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Palexeralfs

JDFC. Other Palexeralfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Palexeralfs

JDFD. Other Palexeralfs that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Palexeralfs

JDFE. Other Palexeralfs that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. Redox depletions with chroma of 2 or less in layers that

also have aquic conditions in normal years (or artificial

drainage) either:

a. Within the upper 25 cm of the argillic or kandic

horizon if its upper boundary is within 50 cm of the

mineral soil surface; or

b. Within 75 cm of the mineral soil surface if the upper

boundary of the argillic or kandic horizon is 50 cm or

more below the mineral soil surface.

Fragiaquic Palexeralfs

JDFF. Other Palexeralfs that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Palexeralfs

JDFG. Other Palexeralfs that have a petrocalcic horizon that

has its upper boundary within 150 cm of the mineral soil

surface.

Petrocalcic Palexeralfs

JDFH. Other Palexeralfs that have an argillic horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more than

20 cm thick, each with an overlying eluvial horizon, and

above these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Palexeralfs

JDFI. Other Palexeralfs that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or

throughout the entire argillic horizon if it is less than 75 cm

thick.

Psammentic Palexeralfs

JDFJ. Other Palexeralfs that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic or kandic horizon at

a depth of 50 cm or more.

Arenic Palexeralfs

JDFK. Other Palexeralfs that have an exchangeable sodium

percentage of 15 or more (or a sodium adsorption ratio of 13 or
76

more) in one or more horizons within 100 cm of the mineral

soil surface.

Natric Palexeralfs

JDFL. Other Palexeralfs that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Palexeralfs

JDFM. Other Palexeralfs that have a calcic horizon within 150

cm of the mineral soil surface.

Calcic Palexeralfs

JDFN. Other Palexeralfs that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Palexeralfs

JDFO. Other Palexeralfs that have an argillic or kandic

horizon that has a base saturation (by sum of cations) of less

than 75 percent throughout.

Ultic Palexeralfs

JDFP. Other Palexeralfs with an argillic or kandic horizon that

has, in the fine-earth fraction, either or both:

1. Less than 35 percent clay throughout all subhorizons

within 15 cm of its upper boundary; or

2. At its upper boundary, a clay increase of less than 20

percent (absolute) within a vertical distance of 7.5 cm and of

less than 15 percent (absolute) within a vertical distance of

2.5 cm.

Haplic Palexeralfs

JDFQ. Other Palexeralfs that have a color value, moist, of 3 or

less and 0.7 percent or more organic carbon either throughout

the upper 10 cm of the mineral soil (unmixed) or throughout the

upper 18 cm of the mineral soil after mixing.

Mollic Palexeralfs

JDFR. Other Palexeralfs.

Typic Palexeralfs

Plinthoxeralfs

Key to Subgroups

JDDA. All Plinthoxeralfs (provisionally).

Typic Plinthoxeralfs

Rhodoxeralfs

Key to Subgroups

JDEA. Rhodoxeralfs that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Rhodoxeralfs

JDEB. Other Rhodoxeralfs that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Rhodoxeralfs

JDEC. Other Rhodoxeralfs that have a petrocalcic horizon

that has its upper boundary within 150 cm of the mineral soil

surface.

Petrocalcic Rhodoxeralfs

JDED. Other Rhodoxeralfs that have a calcic horizon that

has its upper boundary within 150 cm of the mineral soil

surface.

Calcic Rhodoxeralfs

JDEE. Other Rhodoxeralfs that have an argillic or kandic

horizon that is either less than 35 cm thick or is discontinuous

horizontally in each pedon.

Inceptic Rhodoxeralfs

JDEF. Other Rhodoxeralfs.

Typic Rhodoxeralfs
77

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Key to Suborders

DA. Andisols that have either:

1. A histic epipedon; or

2. In a layer above a densic, lithic, or paralithic contact or

in a layer at a depth between 40 and 50 cm either from the

mineral soil surface or from the top of an organic layer with

andic soil properties, whichever is shallowest, aquic

conditions for some time in normal years (or artificial

drainage) and one or more of the following:

a. 2 percent or more redox concentrations; or

b. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on

faces of peds or in the matrix if peds are absent; or

c. Enough active ferrous iron to give a positive reaction

to alpha,alpha-dipyridyl at a time when the soil is not

being irrigated.

Aquands, p. 77

DB. Other Andisols that have, in normal years, a mean annual

soil temperature of 0 o

C or colder and a mean summer soil

temperature that:

1. Is 8 oC or colder if there is no O horizon; or

2. Is 5 oC or colder if there is an O horizon.

Gelands, p. 84

DC. Other Andisols that have a cryic soil temperature regime.

Cryands, p. 81

DD. Other Andisols that have an aridic moisture regime.

Torrands, p. 84

DE. Other Andisols that have a xeric moisture regime.

Xerands, p. 95

DF. Other Andisols that have a 1500 kPa water retention of

less than 15 percent on air-dried samples and less than 30

percent on undried samples throughout 60 percent or more of

the thickness either:

1. Within 60 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever

is shallower, if there is no densic, lithic, or paralithic contact,

duripan, or petrocalcic horizon within that depth; or

2. Between either the mineral soil surface or the top of an

organic layer with andic soil properties, whichever is

shallower, and a densic, lithic, or paralithic contact, a

duripan, or a petrocalcic horizon.

Vitrands, p. 93

DG. Other Andisols that have an ustic moisture regime.

Ustands, p. 92

DH. Other Andisols.

Udands, p. 85

Aquands

Key to Great Groups

DAA. Aquands that have, in normal years, a mean annual soil

temperature of 0 oC or colder and a mean summer soil

temperature that:

1. Is 8 oC or colder if there is no O horizon; or

2. Is 5 oC or colder if there is an O horizon.

Gelaquands, p. 79

DAB. Other Aquands that have a cryic soil temperature

regime.

Cryaquands, p. 78

DAC. Other Aquands that have, in half or more of each

pedon, a placic horizon within 100 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Placaquands, p. 80

DAD. Other Aquands that have, in 75 percent or more of each

pedon, a cemented horizon that has its upper boundary within

100 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is shallower.

Duraquands, p. 78

DAE. Other Aquands that have a 1500 kPa water retention of

CHAPTER 6

Andisols
78 Keys to Soil Taxonomy

less than 15 percent on air-dried samples and less than 30

percent on undried samples throughout 60 percent or more of

the thickness either:

1. Within 60 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever

is shallower, if there is no densic, lithic, or paralithic contact

within that depth; or

2. Between either the mineral soil surface or the top

of an organic layer with andic soil properties,

whichever is shallower, and a densic, lithic, or paralithic

contact.

Vitraquands, p. 80

DAF. Other Aquands that have a melanic epipedon.

Melanaquands, p. 79

DAG. Other Aquands that have episaturation.

Epiaquands, p. 79

DAH. Other Aquands.

Endoaquands, p. 78

Cryaquands

Key to Subgroups

DABA. Cryaquands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Cryaquands

DABB. Other Cryaquands that have a histic epipedon.

Histic Cryaquands

DABC. Other Cryaquands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top of

an organic layer with andic soil properties, whichever is shallower,

a layer 10 cm or more thick with more than 3.0 percent organic

carbon and the colors of a mollic epipedon throughout,

underlying one or more horizons with a total thickness of 10 cm

or more that have a color value, moist, 1 unit or more higher

and an organic-carbon content 1 percent or more (absolute)

lower.

Thaptic Cryaquands

DABD. Other Cryaquands.

Typic Cryaquands

Duraquands

Key to Subgroups

DADA. Duraquands that have a histic epipedon.

Histic Duraquands

DADB. Other Duraquands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 2.0

cmol(+)/kg in the fine-earth fraction of one or more horizons

with a total thickness of 30 cm or more at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower.

Acraquoxic Duraquands

DADC. Other Duraquands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Duraquands

DADD. Other Duraquands.

Typic Duraquands

Endoaquands

Key to Subgroups

DAHA. Endoaquands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Endoaquands

DAHB. Other Endoaquands that have a horizon 15 cm or

more thick that has 20 percent or more (by volume) cemented

soil material and has its upper boundary within 100 cm either of

the mineral soil surface or of the top of an organic layer with

andic soil properties, whichever is shallower.

Duric Endoaquands

DAHC. Other Endoaquands that have a histic epipedon.

Histic Endoaquands

DAHD. Other Endoaquands that have more than 2.0

cmol(+)/kg Al3+ (by 1N KCl) in the fine-earth fraction of one

or more horizons with a total thickness of 10 cm or more at a

depth between 25 and 50 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower.

Alic Endoaquands

DAHE. Other Endoaquands that have, on undried samples, a

1500 kPa water retention of 70 percent or more throughout a

layer 35 cm or more thick within 100 cm either of the mineral
Andisols 79

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soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Hydric Endoaquands

DAHF. Other Endoaquands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Endoaquands

DAHG. Other Endoaquands.

Typic Endoaquands

Epiaquands

Key to Subgroups

DAGA. Epiaquands that have a horizon 15 cm or more thick

that has 20 percent or more (by volume) cemented soil material

and has its upper boundary within 100 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Duric Epiaquands

DAGB. Other Epiaquands that have a histic epipedon.

Histic Epiaquands

DAGC. Other Epiaquands that have more than 2.0

cmol(+)/kg Al3+ (by 1N KCl) in the fine-earth fraction of one or

more horizons with a total thickness of 10 cm or more at a

depth between 25 and 50 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower.

Alic Epiaquands

DAGD. Other Epiaquands that have, on undried samples, a

1500 kPa water retention of 70 percent or more throughout a

layer 35 cm or more thick within 100 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Hydric Epiaquands

DAGE. Other Epiaquands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Epiaquands

DAGF. Other Epiaquands.

Typic Epiaquands

Gelaquands

Key to Subgroups

DAAA. Gelaquands that have a histic epipedon.

Histic Gelaquands

DAAB. Other Gelaquands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Gelaquands

DAAC. Other Gelaquands.

Typic Gelaquands

Melanaquands

Key to Subgroups

DAFA. Melanaquands that have a lithic contact within

50 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is shallower.

Lithic Melanaquands

DAFB. Other Melanaquands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 2.0

cmol(+)/kg in the fine-earth fraction of one or more horizons

with a total thickness of 30 cm or more at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower.

Acraquoxic Melanaquands

DAFC. Other Melanaquands that have both:

1. On undried samples, a 1500 kPa water retention of 70

percent or more throughout a layer 35 cm or more thick

within 100 cm either of the mineral soil surface or of the top

of an organic layer with andic soil properties, whichever is

shallower; and

2. More than 6.0 percent organic carbon and the colors of a
80 Keys to Soil Taxonomy

mollic epipedon throughout a layer 50 cm or more thick

within 60 cm either of the mineral soil surface or of the top

of an organic layer with andic soil properties, whichever is

shallower.

Hydric Pachic Melanaquands

DAFD. Other Melanaquands that have, on undried samples, a

1500 kPa water retention of 70 percent or more throughout a

layer 35 cm or more thick within 100 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Hydric Melanaquands

DAFE. Other Melanaquands that have more than 6.0 percent

organic carbon and the colors of a mollic epipedon throughout a

layer 50 cm or more thick within 60 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Pachic Melanaquands

DAFF. Other Melanaquands that have, at a depth between 40

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Melanaquands

DAFG. Other Melanaquands.

Typic Melanaquands

Placaquands

Key to Subgroups

DACA. Placaquands that have a lithic contact within

50 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is shallower.

Lithic Placaquands

DACB. Other Placaquands that have both:

1. A histic epipedon; and

2. A horizon 15 cm or more thick that has 20 percent or

more (by volume) cemented soil material and has its upper

boundary within 100 cm either of the mineral soil surface or

of the top of an organic layer with andic soil properties,

whichever is shallower.

Duric Histic Placaquands

DACC. Other Placaquands that have a horizon 15 cm or more

thick that has 20 percent or more (by volume) cemented soil

material and has its upper boundary within 100 cm either of the

mineral soil surface or of the top of an organic layer with andic

soil properties, whichever is shallower.

Duric Placaquands

DACD. Other Placaquands that have a histic epipedon.

Histic Placaquands

DACE. Other Placaquands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Placaquands

DAFF. Other Placaquands.

Typic Placaquands

Vitraquands

Key to Subgroups

DAEA. Vitraquands that have a lithic contact within

50 cm either of the mineral soil surface or of the top of

an organic layer with andic soil properties, whichever is

shallower.

Lithic Vitraquands

DAEB. Other Vitraquands that have a horizon 15 cm or more

thick that has 20 percent or more (by volume) cemented soil

material and has its upper boundary within 100 cm either of the

mineral soil surface or of the top of an organic layer with andic

soil properties, whichever is shallower.

Duric Vitraquands

DAEC. Other Vitraquands that have a histic epipedon.

Histic Vitraquands

DAED. Other Vitraquands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Vitraquands

DAEE. Other Vitraquands.

Typic Vitraquands
Andisols 81

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Cryands

Key to Great Groups

DCA. Cryands that have, in 75 percent or more of each

pedon, a cemented horizon that has its upper boundary within

100 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is shallower.

Duricryands, p. 81

DCB. Other Cryands that have, on undried samples, a 1500

kPa water retention of 100 percent or more, by weighted

average, throughout either:

1. One or more layers with a total thickness of 35 cm

between the mineral soil surface or the top of an organic

layer with andic soil properties, whichever is shallower,

and 100 cm from the mineral soil surface or from the top

 of an organic layer with andic soil properties, whichever

is shallower, if there is no densic, lithic, or paralithic contact,

duripan, or petrocalcic horizon within that depth; or

2. 60 percent or more of the horizon thickness between

either the mineral soil surface or the top of an organic layer

with andic soil properties, whichever is shallower, and a

densic, lithic, or paralithic contact, a duripan, or a petrocalcic

horizon.

Hydrocryands, p. 83

DCC. Other Cryands that have a melanic epipedon.

Melanocryands, p. 83

DCD. Other Cryands that have a layer that meets the depth,

thickness, and organic-carbon requirements for a melanic

epipedon.

Fulvicryands, p. 82

DCE. Other Cryands that have a 1500 kPa water retention of

less than 15 percent on air-dried samples and less than 30

percent on undried samples throughout 60 percent or more of

the thickness either:

1. Within 60 cm either of the mineral soil surface or of

the top of an organic layer with andic soil properties,

whichever is shallower, if there is no densic, lithic, or

paralithic contact, duripan, or petrocalcic horizon within

that depth; or

2. Between either the mineral soil surface or the top of an

organic layer with andic soil properties, whichever is

shallower, and a densic, lithic, or paralithic contact, a

duripan, or a petrocalcic horizon.

Vitricryands, p. 83

DCF. Other Cryands.

Haplocryands, p. 82

Duricryands

Key to Subgroups

DCAA. Duricryands that have, in some subhorizon at a depth

between 50 and 100 cm either from the mineral soil surface or

from the top of an organic layer with andic soil properties,

whichever is shallower, aquic conditions for some time in normal

years (or artificial drainage) and one or more of the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Duricryands

DCAB. Other Duricryands that have both:

1. No horizons with more than 2.0 cmol(+)/kg Al3+ (by 1N

KCl) in the fine-earth fraction and with a total thickness of

10 cm or more at a depth between 25 and 50 cm either from

the mineral soil surface or from the top of an organic layer

with andic properties, whichever is shallower; and

2. Saturation with water in one or more layers above the

cemented horizon in normal years for either or both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Eutric Oxyaquic Duricryands

DCAC. Other Duricryands that are saturated with water in

one or more layers above the cemented horizon in normal years

for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Duricryands

DCAD. Other Duricryands that have no horizons with more

than 2.0 cmol(+)/kg Al3+ (by 1N KCl) in the fine-earth fraction

and with a total thickness of 10 cm or more at a depth between

25 and 50 cm either from the mineral soil surface or from the

top of an organic layer with andic properties, whichever is

shallower.

Eutric Duricryands
82 Keys to Soil Taxonomy

DCAE. Other Duricryands.

Typic Duricryands

Fulvicryands

Key to Subgroups

DCDA. Fulvicryands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Fulvicryands

DCDB. Other Fulvicryands that have both:

1. No horizons with more than 2.0 cmol(+)/kg Al3+ (by 1N

KCl) in the fine-earth fraction and with a total thickness of

10 cm or more at a depth between 25 and 50 cm either from

the mineral soil surface or from the top of an organic layer

with andic properties, whichever is shallower; and

2. Throughout a layer 50 cm or more thick within 60 cm

either of the mineral soil surface or of the top of an organic

layer with andic properties, whichever is shallower:

a. More than 6.0 percent organic carbon, by weighted

average; and

b. More than 4.0 percent organic carbon in all parts.

Eutric Pachic Fulvicryands

DCDC. Other Fulvicryands that have no horizons with more

than 2.0 cmol(+)/kg Al3+ (by 1N KCl) in the fine-earth fraction

and with a total thickness of 10 cm or more at a depth between

25 and 50 cm either from the mineral soil surface or from the

top of an organic layer with andic properties, whichever is

shallower.

Eutric Fulvicryands

DCDD. Other Fulvicryands that have, throughout a layer 50

cm or more thick within 60 cm either of the mineral soil surface

or of the top of an organic layer with andic soil properties,

whichever is shallower:

1. More than 6.0 percent organic carbon, by weighted

average; and

2. More than 4.0 percent organic carbon in all parts.

Pachic Fulvicryands

DCDE. Other Fulvicryands that have a 1500 kPa water

retention of less than 15 percent on air-dried samples and less

than 30 percent on undried samples throughout one or more

layers that have andic soil properties and have a total thickness

of 25 cm or more within 100 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Vitric Fulvicryands

DCDF. Other Fulvicryands.

Typic Fulvicryands

Haplocryands

Key to Subgroups

DCFA. Haplocryands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Haplocryands

DCFB. Other Haplocryands that have, in some subhorizon at

a depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Haplocryands

DCFC. Other Haplocryands that are saturated with water

within 100 cm of the mineral soil surface in normal years for

either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplocryands

DCFD. Other Haplocryands that have more than 2.0

cmol(+)/kg Al3+ (by 1N KCl) in the fine-earth fraction of one or

more horizons with a total thickness of 10 cm or more at a

depth between 25 and 50 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower.

Alic Haplocryands

DCFE. Other Haplocryands that have an ablic horizon

overlying a cambic horizon in 50 percent or more in each pedon

or have a spodic horizon in 50 percent or more of each pedon.

Spodic Haplocryands

DCFF. Other Haplocryands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 2.0

cmol(+)/kg in the fine-earth fraction of one or more horizons

with a total thickness of 30 cm or more at a depth between 25 and

100 cm either from the mineral soil surface or from the top of
Andisols 83

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an organic layer with andic soil properties, whichever is

shallower.

Acrudoxic Haplocryands

DCFG. Other Haplocryands that have a 1500 kPa water

retention of less than 15 percent on air-dried samples and less

than 30 percent on undried samples throughout one or more

layers that have andic soil properties and have a total thickness

of 25 cm or more within 100 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Vitric Haplocryands

DCFH. Other Haplocryands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Haplocryands

DCFI. Other Haplocryands that have a xeric moisture regime.

Xeric Haplocryands

DCFJ. Other Haplocryands.

Typic Haplocryands

Hydrocryands

Key to Subgroups

DCBA. Hydrocryands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Hydrocryands

DCBB. Other Hydrocryands that have a placic horizon within

100 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is shallower.

Placic Hydrocryands

DCBC. Other Hydrocryands that have, in one or more

horizons at a depth between 50 and 100 cm either from the

mineral soil surface or from the top of an organic layer with

andic soil properties, whichever is shallower, aquic conditions

for some time in normal years (or artificial drainage) and one or

more of the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent

or more chroma of 2 or less either in redox depletions

on faces of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Hydrocryands

DCBD. Other Hydrocryands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Hydrocryands

DCBE. Other Hydrocryands.

Typic Hydrocryands

Melanocryands

Key to Subgroups

DCCA. Melanocryands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer that has andic soil properties, whichever is shallower.

Lithic Melanocryands

DCCB. Other Melanocryands that have a 1500 kPa water

retention of less than 15 percent on air-dried samples and less

than 30 percent on undried samples throughout one or more

layers that have andic soil properties and have a total thickness

of 25 cm or more within 100 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Vitric Melanocryands

DCCC. Other Melanocryands.

Typic Melanocryands

Vitricryands

Key to Subgroups

DCEA. Vitricryands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer that has andic soil properties, whichever is shallower.

Lithic Vitricryands

DCEB. Other Vitricryands that have, in one or more horizons

at a depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:
84 Keys to Soil Taxonomy

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Vitricryands

DCEC. Other Vitricryands that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Vitricryands

DCED. Other Vitricryands that have an albic horizon

overlying a cambic horizon in 50 percent or more in each pedon

or have a spodic horizon in 50 percent or more of each pedon.

Spodic Vitricryands

DCEE. Other Vitricryands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Vitricryands

DCEF. Other Vitricryands that have a xeric moisture regime

and a mollic or umbric epipedon.

Humic Xeric Vitricryands

DCEG. Other Vitricryands that have a xeric moisture regime.

Xeric Vitricryands

DCEH. Other Vitricryands that have an argillic or kandic

horizon that has both:

1. An upper boundary within 125 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower; and

2. A base saturation (by sum of cations) of less than 35

percent throughout the upper 50 cm or throughout the entire

argillic or kandic horizon if it is less than 50 cm thick.

Ultic Vitricryands

DCEI. Other Vitricryands that have an argillic or kandic

horizon that has its upper boundary within 125 cm either of the

mineral soil surface or of the top of an organic layer with andic

soil properties, whichever is shallower.

Alfic Vitricryands

DCEJ. Other Vitricryands that have a mollic or umbric

epipedon.

Humic Vitricryands

DCEK. Other Vitricryands.

Typic Vitricryands

Gelands

Key to Great Groups

DBA. All Gelands are considered Vitrigelands.

Vitrigelands, p. 84

Vitrigelands

Key to Subgroups

DBAA. Vitrigelands that have a mollic or umbric epipedon.

Humic Vitrigelands

DBAB. Other Vitrigelands.

Typic Vitrigelands

Torrands

Key to Great Groups

DDA. Torrands that have, in 75 percent or more of each

pedon, a cemented horizon that has its upper boundary within

100 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is

shallower.

Duritorrands, p. 85

DDB. Other Torrands that have, on air-dried samples, a 1500

kPa water retention of less than 15 percent throughout 60

percent or more of the thickness either:

1. Within 60 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever

is shallower, if there is no densic, lithic, or paralithic contact,

duripan, or petrocalcic horizon within that depth; or

2. Between either the mineral soil surface or the top of an

organic layer with andic soil properties, whichever is

shallower, and a densic, lithic, or paralithic contact, a

duripan, or a petrocalcic horizon.

Vitritorrands, p. 85

DDC. Other Torrands.

Haplotorrands, p. 85
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Duritorrands

Key to Subgroups

DDAA. Duritorrands that have a petrocalcic horizon that has

its upper boundary within 100 cm of the mineral soil surface.

Petrocalcic Duritorrands

DDAB. Other Duritorrands that have, on air-dried samples, a

1500 kPa water retention of less than 15 percent throughout 60

percent or more of the thickness either:

1. Between either the mineral soil surface or the top of an

organic layer with andic soil properties, whichever is

shallower, if there is no paralithic contact or duripan within

that depth, and a point 60 cm below that depth; or

2. Between either the mineral soil surface or the top of an

organic layer with andic soil properties, whichever is

shallower, and a paralithic contact or a duripan.

Vitric Duritorrands

DDAC. Other Duritorrands.

Typic Duritorrands

Haplotorrands

Key to Subgroups

DDCA. Haplotorrands that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Haplotorrands

DDCB. Other Haplotorrands that have a horizon 15 cm or

more thick that has 20 percent or more (by volume) cemented

soil material and has its upper boundary within 100 cm of the

mineral soil surface.

Duric Haplotorrands

DDCC. Other Haplotorrands that have a calcic horizon that has

its upper boundary within 125 cm of the mineral soil surface.

Calcic Haplotorrands

DDCD. Other Haplotorrands.

Typic Haplotorrands

Vitritorrands

Key to Subgroups

DDBA. Vitritorrands that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Vitritorrands

DDBB. Other Vitritorrands that have a horizon 15 cm or more

thick that has 20 percent or more (by volume) cemented soil

material and has its upper boundary within 100 cm of the

mineral soil surface.

Duric Vitritorrands

DDBC. Other Vitritorrands that have, in one or more horizons

at a depth between 50 and 100 cm from the mineral soil surface,

aquic conditions for some time in normal years (or artificial

drainage) and one or more of the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Vitritorrands

DDBD. Other Vitritorrands that have a calcic horizon that has

its upper boundary within 125 cm of the mineral soil surface.

Calcic Vitritorrands

DDBE. Other Vitritorrands.

Typic Vitritorrands

Udands

Key to Great Groups

DHA. Udands that have, in half or more of each pedon, a

placic horizon within 100 cm either of the mineral soil surface

or of the top of an organic layer with andic soil properties,

whichever is shallower.

Placudands, p. 92

DHB. Other Udands that have, in 75 percent or more of each

pedon, a cemented horizon that has its upper boundary within

100 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is shallower.

Durudands, p. 86

DHC. Other Udands that have a melanic epipedon.

Melanudands, p. 90

DHD. Other Udands that have, on undried samples, a 1500

kPa water retention of 100 percent or more, by weighted

average, throughout either:

1. One or more layers with a total thickness of 35 cm

between the mineral soil surface or the top of an organic

layer with andic soil properties, whichever is shallower,

and 100 cm from the mineral soil surface or from the

top of an organic layer with andic soil properties,
86 Keys to Soil Taxonomy

whichever is shallower, if there is no densic, lithic, or

paralithic contact, duripan, or petrocalcic horizon within that

depth; or

2. 60 percent or more of the horizon thickness between

either the mineral soil surface or the top of an organic layer

with andic soil properties, whichever is shallower, and a

densic, lithic, or paralithic contact, a duripan, or a petrocalcic

horizon.

Hydrudands, p. 89

DHE. Other Udands that have a layer that meets the depth,

thickness, and organic-carbon requirements for a melanic

epipedon.

Fulvudands, p. 86

DHF. Other Udands.

Hapludands, p. 87

Durudands

Key to Subgroups

DHBA. Durudands that have, in one or more horizons above

the cemented horizon, aquic conditions for some time in

normal years (or artificial drainage) and one or more of the

following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Durudands

DHBB. Other Durudands that have no horizons with more

than 2.0 cmol(+)/kg Al3+ (by 1N KCl) in the fine-earth fraction

and with a total thickness of 10 cm or more at a depth between

25 and 50 cm either from the mineral soil surface or from the

top of an organic layer with andic properties, whichever is

shallower.

Eutric Durudands

DHBC. Other Durudands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 2.0

cmol(+)/kg in the fine-earth fraction of one or more horizons

with a total thickness of 30 cm or more at a depth between 25

cm either from the mineral soil surface or from the top of an

organic layer with andic soil properties, whichever is shallower,

and the cemented horizon.

Acrudoxic Durudands

DHBD. Other Durudands that have, on undried samples, a

1500 kPa water retention of 70 percent or more throughout a

layer 35 cm or more thick above the cemented horizon.

Hydric Durudands

DHBE. Other Durudands that have more than 6.0 percent

organic carbon and the colors of a mollic epipedon throughout a

layer 50 cm or more thick within 60 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Pachic Durudands

DHBF. Other Durudands.

Typic Durudands

Fulvudands

Key to Subgroups

DHEA. Fulvudands that have both:

1. A lithic contact within 50 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower; and

2. No horizons with more than 2.0 cmol(+)/kg Al3+ (by 1N

KCl) in the fine-earth fraction and with a total thickness of

10 cm or more at a depth between 25 cm from the mineral

soil surface or from the top of an organic layer with andic

soil properties, whichever is shallower, and the lithic contact.

Eutric Lithic Fulvudands

DHEB. Other Fulvudands that have a lithic contact within 50

cm either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Fulvudands

DHEC. Other Fulvudands that have, in one or more horizons

at a depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Fulvudands

DHED. Other Fulvudands that are saturated with water within

100 cm of the mineral soil surface in normal years for either or

both:
Andisols 87

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1. 20 or more consecutive days; or

2. 30 or more cumulative days

Oxyaquic Fulvudands

DHEE. Other Fulvudands that have, on undried samples, a

1500 kPa water retention of 70 percent or more throughout a

layer 35 cm or more thick within 100 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Hydric Fulvudands

DHEF. Other Fulvudands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 2.0

cmol(+)/kg in the fine-earth fraction of one or more horizons

with a total thickness of 30 cm or more at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower.

Acrudoxic Fulvudands

DHEG. Other Fulvudands that have an argillic or kandic

horizon that has both:

1. An upper boundary within 125 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower; and

2. A base saturation (by sum of cations) of less than 35

percent throughout its upper 50 cm.

Ultic Fulvudands

DHEH. Other Fulvudands that have both:

1. No horizons with more than 2.0 cmol(+)/kg Al3+ (by 1N

KCl) in the fine-earth fraction and with a total thickness of

10 cm or more at a depth between 25 and 50 cm either from

the mineral soil surface or from the top of an organic layer

with andic soil properties, whichever is shallower; and

2. Throughout a layer 50 cm or more thick within 60 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower:

a. More than 6.0 percent organic carbon, by weighted

average; and

b. More than 4.0 percent organic carbon in all parts.

Eutric Pachic Fulvudands

DHEI. Other Fulvudands that have no horizons with more

than 2.0 cmol(+)/kg Al3+ (by 1N KCl) in the fine-earth fraction

and with a total thickness of 10 cm or more at a depth between

25 and 50 cm either from the mineral soil surface or from the

top of an organic layer with andic soil properties, whichever is

shallower.

Eutric Fulvudands

DHEJ. Other Fulvudands that have, throughout a layer 50 cm

or more thick within 60 cm either of the mineral soil surface or

of the top of an organic layer with andic soil properties,

whichever is shallower:

1. More than 6.0 percent organic carbon, by weighted

average; and

2. More than 4.0 percent organic carbon in all parts.

Pachic Fulvudands

DHEK. Other Fulvudands that have, at a depth between 40

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Fulvudands

DHEL. Other Fulvudands.

Typic Fulvudands

Hapludands

Key to Subgroups

DHFA. Hapludands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Hapludands

DHFB. Other Hapludands that have anthraquic conditions.

Anthraquic Hapludands

DHFC. Other Hapludands that have both:

1. A horizon 15 cm or more thick that has 20 percent or

more (by volume) cemented soil material and has its upper

boundary within 100 cm either of the mineral soil surface or

of the top of an organic layer with andic soil properties,

whichever is shallower; and

2. In one or more horizons at a depth between 50 and 100

cm either from the mineral soil surface or from the top of an

organic layer with andic soil properties, whichever is

shallower, aquic conditions for some time in normal years

(or artificial drainage) and one or more of the following:

a. 2 percent or more redox concentrations; or

b. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on

faces of peds or in the matrix if peds are absent; or
88 Keys to Soil Taxonomy

c. Enough active ferrous iron to give a positive reaction

to alpha,alpha-dipyridyl at a time when the soil is not

being irrigated.

Aquic Duric Hapludands

DHFD. Other Hapludands that have a horizon 15 cm or more

thick that has 20 percent or more (by volume) cemented soil

material and has its upper boundary within 100 cm either of the

mineral soil surface or of the top of an organic layer with andic

soil properties, whichever is shallower.

Duric Hapludands

DHFE. Other Hapludands that have, in one or more horizons

at a depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Hapludands

DHFF. Other Hapludands that are saturated with water within

100 cm of the mineral soil surface in normal years for either or

both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days

Oxyaquic Hapludands

DHFG. Other Hapludands that have more than 2.0

cmol(+)/kg Al3+ (by 1N KCl) in the fine-earth fraction of one or

more horizons with a total thickness of 10 cm or more at a

depth between 25 and 50 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower.

Alic Hapludands

DHFH. Other Hapludands that have both:

1. Extractable bases (by NH4

OAc) plus 1N KCl-extractable

Al3+ totaling less than 2.0 cmol(+)/kg in the fine-earth

fraction of one or more horizons with a total thickness of 30

cm or more at a depth between 25 and 100 cm either from

the mineral soil surface or from the top of an organic layer

with andic soil properties, whichever is shallower; and

2. On undried samples, a 1500 kPa water retention of 70

percent or more throughout a layer 35 cm or more thick

within 100 cm either of the mineral soil surface or of the top

of an organic layer with andic soil properties, whichever is

shallower.

Acrudoxic Hydric Hapludands

DHFI. Other Hapludands that have, at a depth between 25 and

100 cm either from the mineral soil surface or from the top of

an organic layer with andic soil properties, whichever is

shallower, both:

1. Extractable bases (by NH4

OAc) plus 1N KCl-extractable

Al3+ totaling less than 2.0 cmol(+)/kg in the fine-earth

fraction of one or more horizons with a total thickness of 30

cm or more; and

2. A layer 10 cm or more thick with more than 3.0 percent

organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1

unit or more higher and an organic-carbon content 1 percent

or more (absolute) lower.

Acrudoxic Thaptic Hapludands

DHFJ. Other Hapludands that have both:

1. Extractable bases (by NH4

OAc) plus 1N KClextractable Al3+ totaling less than 2.0 cmol(+)/kg in the

fine-earth fraction of one or more horizons with a total

thickness of 30 cm or more at a depth between 25 and 100

cm either from the mineral soil surface or from the top of an

organic layer with andic soil properties, whichever is

shallower; and

2. An argillic or kandic horizon that has both:

a. An upper boundary within 125 cm either of the

mineral soil surface or of the top of an organic layer with

andic soil properties, whichever is shallower; and

b. A base saturation (by sum of cations) of less than 35

percent throughout its upper 50 cm.

Acrudoxic Ultic Hapludands

DHFK. Other Hapludands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 2.0

cmol(+)/kg in the fine-earth fraction of one or more horizons

with a total thickness of 30 cm or more at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower.

Acrudoxic Hapludands

DHFL. Other Hapludands that have a 1500 kPa water

retention of less than 15 percent on air-dried samples and less

than 30 percent on undried samples throughout one or more

layers that have andic soil properties and have a total thickness

of 25 cm or more within 100 cm either of the mineral soil
Andisols 89

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surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Vitric Hapludands

DHFM. Other Hapludands that have both:

1. On undried samples, a 1500 kPa water retention of 70

percent or more throughout a layer 35 cm or more thick

within 100 cm either of the mineral soil surface or of the top

of an organic layer with andic soil properties, whichever is

shallower; and

2. At a depth between 25 and 100 cm either from the

mineral soil surface or from the top of an organic layer with

andic soil properties, whichever is shallower, a layer 10 cm

or more thick with more than 3.0 percent organic carbon and

the colors of a mollic epipedon throughout, underlying one

or more horizons with a total thickness of 10 cm or more that

have a color value, moist, 1 unit or more higher and an

organic-carbon content 1 percent or more (absolute) lower.

Hydric Thaptic Hapludands

DHFN. Other Hapludands that have, on undried samples, a

1500 kPa water retention of 70 percent or more throughout a

layer 35 cm or more thick within 100 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Hydric Hapludands

DHFO. Other Hapludands that have both:

1. A sum of extractable bases of more than 25.0

cmol(+)/kg in the fine-earth fraction throughout one or more

horizons with a total thickness of 15 cm or more at a depth

between 25 and 75 cm either from the mineral soil surface or

from the top of an organic layer with andic soil properties,

whichever is shallower; and

2. At a depth between 25 and 100 cm either from the

mineral soil surface or from the top of an organic layer with

andic soil properties, whichever is shallower, a layer 10 cm

or more thick with more than 3.0 percent organic carbon and

the colors of a mollic epipedon throughout, underlying one

or more horizons with a total thickness of 10 cm or more

that have a color value, moist, 1 unit or more higher and

an organic-carbon content 1 percent or more (absolute)

lower.

Eutric Thaptic Hapludands

DHFP. Other Hapludands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Hapludands

DHFQ. Other Hapludands that have a sum of extractable

bases of more than 25.0 cmol(+)/kg in the fine-earth fraction

throughout one or more horizons with a total thickness of 15

cm or more at a depth between 25 and 75 cm either from the

mineral soil surface or from the top of an organic layer with

andic soil properties, whichever is shallower.

Eutric Hapludands

DHFR. Other Hapludands that have an oxic horizon that has

its upper boundary within 125 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Oxic Hapludands

DHFS. Other Hapludands that have an argillic or kandic

horizon that has both:

1. An upper boundary within 125 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower; and

2. A base saturation (by sum of cations) of less than 35

percent throughout its upper 50 cm.

Ultic Hapludands

DHFT. Other Hapludands that have an argillic or kandic

horizon that has its upper boundary within 125 cm either of the

mineral soil surface or of the top of an organic layer with andic

soil properties, whichever is shallower.

Alfic Hapludands

DHFU. Other Hapludands.

Typic Hapludands

Hydrudands

Key to Subgroups

DHDA. Hydrudands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Hydrudands

DHDB. Other Hydrudands that have, in one or more horizons

at a depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:
90 Keys to Soil Taxonomy

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Hydrudands

DHDC. Other Hydrudands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, both:

1. Extractable bases (by NH4

OAc) plus 1N KCl-extractable

Al3+ totaling less than 2.0 cmol(+)/kg in the fine-earth

fraction of one or more horizons with a total thickness of 30

cm or more; and

2. A layer 10 cm or more thick with more than 3.0 percent

organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1

unit or more higher and an organic-carbon content 1 percent

or more (absolute) lower.

Acrudoxic Thaptic Hydrudands

DHDD. Other Hydrudands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 2.0

cmol(+)/kg in the fine-earth fraction of one or more horizons

with a total thickness of 30 cm or more at a depth between 25 and

100 cm either from the mineral soil surface or from the top of

an organic layer with andic soil properties, whichever is

shallower.

Acrudoxic Hydrudands

DHDE. Other Hydrudands that have, at a depth between 25 and

100 cm either from the mineral soil surface or from the top of

an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Hydrudands

DHDF. Other Hydrudands that have a sum of extractable

bases of more than 25.0 cmol(+)/kg in the fine-earth fraction

throughout one or more horizons with a total thickness of 15

cm or more at a depth between 25 and 75 cm either from the

mineral soil surface or from the top of an organic layer with

andic soil properties, whichever is shallower.

Eutric Hydrudands

DHDG. Other Hydrudands that have an argillic or kandic

horizon that has both:

1. An upper boundary within 125 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower; and

2. A base saturation (by sum of cations) of less than 35

percent throughout its upper 50 cm.

Ultic Hydrudands

DHDH. Other Hydrudands.

Typic Hydrudands

Melanudands

Key to Subgroups

DHCA. Melanudands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer that has andic soil properties, whichever is shallower.

Lithic Melanudands

DHCB. Other Melanudands that have anthraquic conditions.

Anthraquic Melanudands

DHCC. Other Melanudands that have, in one or more

horizons at a depth between 50 and 100 cm either from the

mineral soil surface or from the top of an organic layer with

andic soil properties, whichever is shallower, aquic conditions

for some time in normal years (or artificial drainage) and one or

more of the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Melanudands

DHCD. Other Melanudands that have both:

1. Extractable bases (by NH4

OAc) plus 1N KCl-extractable

Al3+ totaling less than 2.0 cmol(+)/kg in the fine-earth

fraction of one or more horizons with a total thickness of 30

cm or more at a depth between 25 and 100 cm either from

the mineral soil surface or from the top of an organic layer

with andic soil properties, whichever is shallower; and

2. A 1500 kPa water retention of less than 15 percent on

air-dried samples and less than 30 percent on undried

samples throughout one or more layers that have andic soil

properties and have a total thickness of 25 cm or more within

100 cm either of the mineral soil surface or of the top of an
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organic layer with andic soil properties, whichever is

shallower.

Acrudoxic Vitric Melanudands

DHCE. Other Melanudands that have both:

1. Extractable bases (by NH4

OAc) plus 1N KCl-extractable

Al3+ totaling less than 2.0 cmol(+)/kg in the fine-earth

fraction of one or more horizons with a total thickness of 30

cm or more at a depth between 25 and 100 cm either from

the mineral soil surface or from the top of an organic layer

with andic soil properties, whichever is shallower; and

2. On undried samples, a 1500 kPa water retention of 70

percent or more throughout a layer 35 cm or more thick

within 100 cm either of the mineral soil surface or of the top

of an organic layer with andic soil properties, whichever is

shallower.

Acrudoxic Hydric Melanudands

DHCF. Other Melanudands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 2.0

cmol(+)/kg in the fine-earth fraction of one or more horizons

with a total thickness of 30 cm or more at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower.

Acrudoxic Melanudands

DHCG. Other Melanudands that have both:

1. More than 6.0 percent organic carbon and the colors of a

mollic epipedon throughout a layer 50 cm or more thick

within 60 cm either of the mineral soil surface or of the top

of an organic layer with andic soil properties, whichever is

shallower; and

2. A 1500 kPa water retention of less than 15 percent on

air-dried samples and less than 30 percent on undried

samples throughout one or more layers that have andic soil

properties and have a total thickness of 25 cm or more within

100 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is

shallower.

Pachic Vitric Melanudands

DGCH. Other Melanudands that have a 1500 kPa water

retention of less than 15 percent on air-dried samples and less

than 30 percent on undried samples throughout one or more

layers that have andic soil properties and have a total thickness

of 25 cm or more within 100 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Vitric Melanudands

DHCI. Other Melanudands that have both:

1. On undried samples, a 1500 kPa water retention of 70

percent or more throughout a layer 35 cm or more thick

within 100 cm either of the mineral soil surface or of the top

of an organic layer with andic soil properties, whichever is

shallower; and

2. More than 6.0 percent organic carbon and the colors of a

mollic epipedon throughout a layer 50 cm or more thick

within 60 cm either of the mineral soil surface or of the top

of an organic layer with andic soil properties, whichever is

shallower.

Hydric Pachic Melanudands

DHCJ. Other Melanudands that have more than 6.0 percent

organic carbon and the colors of a mollic epipedon throughout a

layer 50 cm or more thick within 60 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Pachic Melanudands

DHCK. Other Melanudands that have, on undried samples, a

1500 kPa water retention of 70 percent or more throughout a

layer 35 cm or more thick within 100 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Hydric Melanudands

DHCL. Other Melanudands that have, at a depth between 40

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Melanudands

DHCM. Other Melanudands that have an argillic or kandic

horizon that has both:

1. An upper boundary within 125 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower; and

2. A base saturation (by sum of cations) of less than 35

percent throughout its upper 50 cm.

Ultic Melanudands

DHCN. Other Melanudands that have a sum of extractable

bases of more than 25.0 cmol(+)/kg in the fine-earth fraction

throughout one or more horizons with a total thickness of 15

cm or more at a depth between 25 and 75 cm either from the

mineral soil surface or from the top of an organic layer with

andic soil properties, whichever is shallower.

Eutric Melanudands
92 Keys to Soil Taxonomy

DHCO. Other Melanudands.

Typic Melanudands

Placudands

Key to Subgroups

DHAA. Placudands that have a lithic contact within

50 cm either of the mineral soil surface or of the top of an

organic layer that has andic soil properties, whichever is

shallower.

Lithic Placudands

DHAB. Other Placudands that have, in one or more horizons

at a depth between 50 cm either from the mineral soil surface or

from the top of an organic layer with andic soil properties,

whichever is shallower, and the placic horizon, aquic conditions

for some time in normal years (or artificial drainage) and one or

more of the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Placudands

DHAC. Other Placudands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 2.0

cmol(+)/kg in the fine-earth fraction of one or more horizons

with a total thickness of 30 cm or more at a depth between 25

cm either from the mineral soil surface or from the top of an

organic layer with andic soil properties, whichever is shallower,

and the placic horizon.

Acrudoxic Placudands

DHAD. Other Placudands that have, on undried samples, a

1500 kPa water retention of 70 percent or more throughout a

layer 35 cm or more thick within 100 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Hydric Placudands

DHAE. Other Placudands.

Typic Placudands

Ustands

Key to Great Groups

DGA. Ustands that have, in 75 percent or more of each

pedon, a cemented horizon that has its upper boundary within

100 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is shallower.

Durustands, p. 92

DGB. Other Ustands.

Haplustands, p. 92

Durustands

Key to Subgroups

DGAA. Durustands that have, in one or more horizons at a

depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Durustands

DGAB. Other Durustands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Durustands

DGAC. Other Durustands that have a melanic, mollic, or

umbric epipedon.

Humic Durustands

DGAD. Other Durustands.

Typic Durustands

Haplustands

Key to Subgroups

DGBA. Haplustands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Haplustands

DGBB. Other Haplustands that have, in one or more horizons
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at a depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Haplustands

DGBC. Other Haplustands that have both:

1. Extractable bases (by NH4

OAc) plus 1N KCl-extractable

Al3+ totaling less than 15.0 cmol(+)/kg in the fine-earth

fraction throughout one or more horizons with a total

thickness of 60 cm or more within 75 cm either of the

mineral soil surface or of the top of an organic layer with

andic soil properties, whichever is shallower; and

2. A 1500 kPa water retention of less than 15 percent on

air-dried samples and less than 30 percent on undried

samples throughout one or more layers that have andic soil

properties and have a total thickness of 25 cm or more within

100 cm either of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is shallower.

Dystric Vitric Haplustands

DGBD. Other Haplustands that have a 1500 kPa water

retention of less than 15 percent on air-dried samples and less

than 30 percent on undried samples throughout one or more

layers that have andic soil properties and have a total thickness

of 25 cm or more within 100 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Vitric Haplustands

DGBE. Other Haplustands that have more than 6.0 percent

organic carbon and the colors of a mollic epipedon throughout a

layer 50 cm or more thick within 60 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Pachic Haplustands

DGBF. Other Haplustands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Haplustands

DGBG. Other Haplustands that have a calcic horizon that has

its upper boundary within 125 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Calcic Haplustands

DGBH. Other Haplustands that have extractable bases (by

NH4

OAc) plus 1N KCl-extractable Al3+ totaling less than 15.0

cmol(+)/kg in the fine-earth fraction throughout one or more

horizons with a total thickness of 60 cm or more within 75 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Dystric Haplustands

DGBI. Other Haplustands that have an oxic horizon that has

its upper boundary within 125 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Oxic Haplustands

DGBJ. Other Haplustands that have an argillic or kandic

horizon that has both:

1. An upper boundary within 125 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower; and

2. A base saturation (by sum of cations) of less than 35

percent throughout the upper 50 cm or throughout the entire

argillic or kandic horizon if it is less than 50 cm thick.

Ultic Haplustands

DGBK. Other Haplustands that have an argillic or kandic

horizon that has its upper boundary within 125 cm either of the

mineral soil surface or of the top of an organic layer with andic

soil properties, whichever is shallower.

Alfic Haplustands

DGBL. Other Haplustands that have a melanic, mollic, or

umbric epipedon.

Humic Haplustands

DGBM. Other Haplustands.

Typic Haplustands

Vitrands

Key to Great Groups

DFA. Vitrands that have an ustic moisture regime.

Ustivitrands, p. 94
94 Keys to Soil Taxonomy

DFB. Other Vitrands.

Udivitrands, p. 94

Udivitrands

Key to Subgroups

DFBA. Udivitrands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Udivitrands

DFBB. Other Udivitrands that have, in one or more horizons

at a depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Udivitrands

DFBC. Other Udivitrands that are saturated with water within

100 cm of the mineral soil surface in normal years for either or

both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days

Oxyaquic Udivitrands

DFBD. Other Udivitrands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top

of an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Udivitrands

DFBE. Other Udivitrands that have both:

1. An argillic or kandic horizon that has its upper boundary

within 125 cm of the mineral soil surface or of the upper

boundary of an organic layer with andic soil properties,

whichever is shallower; and

2. A base saturation (by sum of cations) of less than 35

percent throughout the upper 50 cm of the argillic or kandic

horizon.

Ultic Udivitrands

DFBF. Other Udivitrands that have an argillic or kandic

horizon that has its upper boundary within 125 cm of the

mineral soil surface or of the upper boundary of an organic

layer with andic soil properties, whichever is shallower.

Alfic Udivitrands

DFBG. Other Udivitrands that have a melanic, mollic, or

umbric epipedon.

Humic Udivitrands

DFBH. Other Udivitrands.

Typic Udivitrands

Ustivitrands

Key to Subgroups

DFAA. Ustivitrands that have a lithic contact within 50 cm

either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Lithic Ustivitrands

DFAB. Other Ustivitrands that have, in one or more horizons

at a depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Ustivitrands

DFAC. Other Ustivitrands that have, at a depth between 25

and 100 cm either from the mineral soil surface or from the top of

an organic layer with andic soil properties, whichever is shallower,

a layer 10 cm or more thick with more than 3.0 percent organic

carbon and the colors of a mollic epipedon throughout,

underlying one or more horizons with a total thickness of 10 cm

or more that have a color value, moist, 1 unit or more higher

and an organic-carbon content 1 percent or more (absolute)

lower.

Thaptic Ustivitrands
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DFAD. Other Ustivitrands that have a calcic horizon that has

its upper boundary within 125 cm either of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Calcic Ustivitrands

DFAE. Other Ustivitrands that have a melanic, mollic, or

umbric epipedon.

Humic Ustivitrands

DFAF. Other Ustivitrands.

Typic Ustivitrands

Xerands

Key to Great Groups

DEA. Xerands that have a 1500 kPa water retention of less

than 15 percent on air-dried samples and less than 30 percent on

undried samples throughout 60 percent or more of the thickness

either:

1. Within 60 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever

is shallower, if there is no densic, lithic, or paralithic contact,

duripan, or petrocalcic horizon within that depth; or

2. Between either the mineral soil surface or the top of an

organic layer with andic soil properties, whichever is

shallower, and a densic, lithic, or paralithic contact, a

duripan, or a petrocalcic horizon.

Vitrixerands, p. 96

DEB. Other Xerands that have a melanic epipedon.

Melanoxerands, p. 96

DEC. Other Xerands.

Haploxerands, p. 95

Haploxerands

Key to Subgroups

DECA. Haploxerands that have a lithic contact within 50 cm

of the mineral soil surface or of the top of an organic layer with

andic soil properties, whichever is shallower.

Lithic Haploxerands

DECB. Other Haploxerands that have, in one or more

horizons at a depth between 50 and 100 cm either from the

mineral soil surface or from the top of an organic layer with

andic soil properties, whichever is shallower, aquic conditions

for some time in normal years (or artificial drainage) and one or

more of the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Haploxerands

DECC. Other Haploxerands that have, at a depth between

25 and 100 cm from the mineral soil surface or from the top of

an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Haploxerands

DECD. Other Haploxerands that have a calcic horizon that

has its upper boundary within 125 cm of the mineral soil

surface.

Calcic Haploxerands

DECE. Other Haploxerands that have an argillic or kandic

horizon that has both:

1. An upper boundary within 125 cm of the mineral soil

surface or of the top of an organic layer with andic soil

properties, whichever is shallower; and

2. A base saturation (by sum of cations) of less than 35

percent throughout its upper 50 cm.

Ultic Haploxerands

DECF. Other Haploxerands that have both:

1. A mollic or umbric epipedon; and

2. An argillic or kandic horizon that has its upper boundary

within 125 cm of the mineral soil surface or of the top of an

organic layer with andic soil properties, whichever is

shallower.

Alfic Humic Haploxerands

DECG. Other Haploxerands that have an argillic or kandic

horizon that has its upper boundary within 125 cm of the

mineral soil surface or of the top of an organic layer with andic

soil properties, whichever is shallower.

Alfic Haploxerands

DECH. Other Haploxerands that have a mollic or umbric

epipedon.

Humic Haploxerands
96

DECI. Other Haploxerands.

Typic Haploxerands

Melanoxerands

Key to Subgroups

DEBA. Melanoxerands that have more than 6.0 percent

organic carbon and the colors of a mollic epipedon throughout a

layer 50 cm or more thick within 60 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower.

Pachic Melanoxerands

DEBB. Other Melanoxerands.

Typic Melanoxerands

Vitrixerands

Key to Subgroups

DEAA. Vitrixerands that have a lithic contact within 50 cm of

the mineral soil surface or of the top of an organic layer with

andic soil properties, whichever is shallower.

Lithic Vitrixerands

DEAB. Other Vitrixerands that have, in one or more horizons

at a depth between 50 and 100 cm either from the mineral soil

surface or from the top of an organic layer with andic soil

properties, whichever is shallower, aquic conditions for some

time in normal years (or artificial drainage) and one or more of

the following:

1. 2 percent or more redox concentrations; or

2. A color value, moist, of 4 or more and 50 percent or

more chroma of 2 or less either in redox depletions on faces

of peds or in the matrix if peds are absent; or

3. Enough active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquic Vitrixerands

DEAC. Other Vitrixerands that have, at a depth between 25

and 100 cm from the mineral soil surface or from the top of

an organic layer with andic soil properties, whichever is

shallower, a layer 10 cm or more thick with more than 3.0

percent organic carbon and the colors of a mollic epipedon

throughout, underlying one or more horizons with a total

thickness of 10 cm or more that have a color value, moist, 1 unit

or more higher and an organic-carbon content 1 percent or more

(absolute) lower.

Thaptic Vitrixerands

DEAD. Other Vitrixerands that have both:

1. A melanic, mollic, or umbric epipedon; and

2. An argillic or kandic horizon that has its upper boundary

within 125 cm of the mineral soil surface or of the top of

an organic layer with andic soil properties, whichever is

shallower.

Alfic Humic Vitrixerands

DEAE. Other Vitrixerands that have an argillic or kandic

horizon that has both:

1. An upper boundary within 125 cm either of the mineral

soil surface or of the top of an organic layer with andic soil

properties, whichever is shallower; and

2. A base saturation (by sum of cations) of less than

35 percent throughout the upper 50 cm or throughout the

entire argillic or kandic horizon if it is less than 50 cm

thick.

Ultic Vitrixerands

DEAF. Other Vitrixerands that have an argillic or kandic

horizon that has its upper boundary within 125 cm of the

mineral soil surface or of the top of an organic layer with andic

soil properties, whichever is shallower.

Alfic Vitrixerands

DEAG. Other Vitrixerands that have a melanic, mollic, or

umbric epipedon.

Humic Vitrixerands

DEAH. Other Vitrixerands.

Typic Vitrixerands
97

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Key to Suborders

GA. Aridisols that have a cryic soil temperature regime.

Cryids, p. 112

GB. Other Aridisols that have a salic horizon that has its

upper boundary within 100 cm of the soil surface.

Salids, p. 122

GC. Other Aridisols that have a duripan that has its upper

boundary within 100 cm of the soil surface.

Durids, p. 115

GD. Other Aridisols that have a gypsic or petrogypsic

horizon that has its upper boundary within 100 cm of the soil

surface and do not have a petrocalcic horizon overlying these

horizons.

Gypsids, p. 118

GE. Other Aridisols that have an argillic or natric horizon and

do not have a petrocalcic horizon that has an upper boundary

within 100 cm of the soil surface.

Argids, p. 97

GF. Other Aridisols that have a calcic or petrocalcic horizon

that has its upper boundary within 100 cm of the soil surface.

Calcids, p. 105

GG. Other Aridisols.

Cambids, p. 108

Argids

Key to Great Groups

GEA. Argids that have a duripan or a petrocalcic or

petrogypsic horizon that has its upper boundary within 150 cm

of the soil surface.

Petroargids, p. 105

GEB. Other Argids that have a natric horizon.

Natrargids, p. 102

GEC. Other Argids that do not have a densic, lithic, or

paralithic contact within 50 cm of the soil surface and have

either:

1. A clay increase of 15 percent or more (absolute) within

a vertical distance of 2.5 cm either within the argillic horizon

or at its upper boundary; or

2. An argillic horizon that extends to 150 cm or more from

the soil surface, that does not have a clay decrease with

increasing depth of 20 percent or more (relative) from the

maximum clay content, and that has, in 50 percent or more

of the matrix in some part between 100 and 150 cm, either:

a. Hue of 7.5YR or redder and chroma of 5 or more;

or

b. Hue of 7.5YR or redder and value, moist, of 3 or less

and value, dry, of 4 or less.

Paleargids, p. 104

GED. Other Argids that have a gypsic horizon that has its

upper boundary within 150 cm of the soil surface.

Gypsiargids, p. 99

GEE. Other Argids that have a calcic horizon that has its

upper boundary within 150 cm of the soil surface.

Calciargids, p. 97

GEF. Other Argids.

Haplargids, p. 100

Calciargids

Key to Subgroups

GEEA. Calciargids that have a lithic contact within 50 cm of

the soil surface.

Lithic Calciargids

GEEB. Other Calciargids that have both:

1. One or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or

b. A linear extensibility of 6.0 cm or more between the

CHAPTER 7

Aridisols
98 Keys to Soil Taxonomy

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact if shallower; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 oC or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Xerertic Calciargids

GEEC. Other Calciargids that have both:

1. One or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or

b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact if shallower; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Ustertic Calciargids

GEED. Other Calciargids that have one or both of the

following:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide through a thickness of 30 cm or more for some

time in normal years and slickensides or wedge-shaped

aggregates in a layer 15 cm or more thick that has its upper

boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact if shallower.

Vertic Calciargids

GEEE. Other Calciargids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within

100 cm of the soil surface for 1 month or more in normal

years.

Aquic Calciargids

GEEF. Other Calciargids that have:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the soil surface to the top of an

argillic horizon at a depth of 50 cm or more; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and a soil

moisture regime that borders on ustic.

Arenic Ustic Calciargids

GEEG. Other Calciargids that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the soil

surface to the top of an argillic horizon at a depth of 50 cm or

more.

Arenic Calciargids

GEEH. Other Calciargids that have the following combination

of characteristics:

1. Have one or more horizons, within 100 cm of the soil

surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) durinodes or are

brittle and have at least a firm rupture-resistance class when

moist; and

2. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and have a

soil moisture regime that borders on xeric.

Durinodic Xeric Calciargids

GEEI. Other Calciargids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes or are brittle and have at least a firm ruptureresistance class when moist.

Durinodic Calciargids

GEEJ. Other Calciargids that:

1. Are dry in all parts of the moisture control section

for less than three-fourths of the time (cumulative) when

the soil temperature at a depth of 50 cm is 5 o

C or higher and

have a soil moisture regime that borders on xeric;

and

2. Have one or more horizons, within 100 cm of the soil

surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) nodules or

concretions.

Petronodic Xeric Calciargids

GEEK. Other Calciargids that:

1. Are dry in all parts of the moisture control section

for less than three-fourths of the time (cumulative) when

the soil temperature at a depth of 50 cm is 5 o

C or higher and

have a soil moisture regime that borders on ustic;

and

2. Have one or more horizons, within 100 cm of the soil
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surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) nodules or

concretions.

Petronodic Ustic Calciargids

GEEL. Other Calciargids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) nodules or concretions.

Petronodic Calciargids

GEEM. Other Calciargids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Calciargids

GEEN. Other Calciargids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Calciargids

GEEO. Other Calciargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

xeric.

Xeric Calciargids

GEEP. Other Calciargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

ustic.

Ustic Calciargids

GEEQ. Other Calciargids.

Typic Calciargids

Gypsiargids

Key to Subgroups

GEDA. Gypsiargids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Are saturated with water in one or more layers within

100 cm of the soil surface for 1 month or more in normal

years.

Aquic Gypsiargids

GEDB. Other Gypsiargids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that either contain 20 percent or

more (by volume) durinodes or are brittle and have at least a

firm rupture-resistance class when moist.

Durinodic Gypsiargids

GEDC. Other Gypsiargids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Gypsiargids

GEDD. Other Gypsiargids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:
100 Keys to Soil Taxonomy

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Gypsiargids

GEDE. Other Gypsiargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

xeric.

Xeric Gypsiargids

GEDF. Other Gypsiargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Gypsiargids

GEDG. Other Gypsiargids.

Typic Gypsiargids

Haplargids

Key to Subgroups

GEFA. Haplargids that have:

1. A lithic contact within 50 cm of the soil surface; and

2. An argillic horizon that is discontinuous throughout

each pedon.

Lithic Ruptic-Entic Haplargids

GEFB. Other Haplargids that have:

1. A lithic contact within 50 cm of the soil surface;

and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Lithic Xeric Haplargids

GEFC. Other Haplargids that have:

1. A lithic contact within 50 cm of the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Lithic Ustic Haplargids

GEFD. Other Haplargids that have a lithic contact within 50

cm of the soil surface.

Lithic Haplargids

GEFE. Other Haplargids that have both:

1. One or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or

b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact if shallower; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Xerertic Haplargids

GEFF. Other Haplargids that have both:

1. One or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the soil surface;

or

b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact if shallower; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Ustertic Haplargids

GEFG. Other Haplargids that have one or both of the

following:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide through a thickness of 30 cm or more for some

time in normal years and slickensides or wedge-shaped

aggregates in a layer 15 cm or more thick that has its upper

boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil
Aridisols 101

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surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact if shallower.

Vertic Haplargids

GEFH. Other Haplargids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within

100 cm of the soil surface for 1 month or more in normal

years.

Aquic Haplargids

GEFI. Other Haplargids that have:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the soil surface to the top of an

argillic horizon at a depth of 50 cm or more; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and a soil

moisture regime that borders on ustic.

Arenic Ustic Haplargids

GEFJ. Other Haplargids that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the soil

surface to the top of an argillic horizon at a depth of 50 cm or

more.

Arenic Haplargids

GEFK. Other Haplargids that have:

1. One or more horizons, within 100 cm of the soil surface

and with a combined thickness of 15 cm or more, that

contain 20 percent or more (by volume) durinodes or are

brittle and have at least a firm rupture-resistance class when

moist; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Durinodic Xeric Haplargids

GEFL. Other Haplargids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes or are brittle and have at least a firm ruptureresistance class when moist.

Durinodic Haplargids

GEFM. Other Haplargids that:

1. Have one or more horizons, within 100 cm of the soil

surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) nodules or

concretions; and

2. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and have a

soil moisture regime that borders on ustic.

Petronodic Ustic Haplargids

GEFN. Other Haplargids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) nodules or concretions.

Petronodic Haplargids

GEFO. Other Haplargids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Haplargids

GEFP. Other Haplargids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Haplargids

GEFQ. Other Haplargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

xeric.

Xeric Haplargids
102 Keys to Soil Taxonomy

GEFR. Other Haplargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 oC or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Haplargids

GEFS. Other Haplargids.

Typic Haplargids

Natrargids

Key to Subgroups

GEBA. Natrargids that have both of the following:

1. A lithic contact within 50 cm of the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 oC or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Lithic Xeric Natrargids

GEBB. Other Natrargids that have both of the following:

1. A lithic contact within 50 cm of the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Lithic Ustic Natrargids

GEBC. Other Natrargids that have a lithic contact within 50

cm of the soil surface.

Lithic Natrargids

GEBD. Other Natrargids that:

1. Are dry in all parts of the moisture control section less

than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and the

moisture regime borders a xeric regime; and

2. Have one or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in most years, slickensides, or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or

b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Xerertic Natrargids

GEBE. Other Natrargids that:

1. Are dry in all parts of the moisture control section less

than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and the

moisture regime borders an ustic regime; and

2. Have one or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in most years, slickensides, or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or

b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Ustertic Natrargids

GEBF. Other Natrargids that have one or both of the

following:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide through a thickness of 30 cm or more for some

time in normal years and slickensides or wedge-shaped

aggregates in a layer 15 cm or more thick that has its upper

boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Vertic Natrargids

GEBG. Other Natrargids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within 100

cm of the soil surface for 1 month or more in normal years.

Aquic Natrargids

GEBH. Other Natrargids that meet both of the following:

1. Have one or more horizons, within 100 cm of the soil

surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) durinodes or are

brittle and have at least a firm rupture-resistance class when

moist; and

2. Are dry in all parts of the moisture control section

for less than three-fourths of the time (cumulative)

when the soil temperature is 5 o

C or higher at a depth

of 50 cm and have a soil moisture regime that borders on

xeric.

Durinodic Xeric Natrargids
Aridisols 103

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GEBI. Other Natrargids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes or are brittle and have at least a firm ruptureresistance class when moist.

Durinodic Natrargids

GEBJ. Other Natrargids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) nodules or concretions.

Petronodic Natrargids

GEBK. Other Natrargids that have:

1. Skeletans covering 10 percent or more of the surfaces of

peds at a depth 2.5 cm or more below the upper boundary of

the natric horizon; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Glossic Ustic Natrargids

GEBL. Other Natrargids that have:

1. An exchangeable sodium percentage of less than 15 (or

an SAR of less than 13) in 50 percent or more of the natric

horizon; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Haplic Ustic Natrargids

GEBM. Other Natrargids that have:

1. An exchangeable sodium percentage of less than 15

(or an SAR of less than 13) in 50 percent or more of the

natric horizon; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Haploxeralfic Natrargids

GEBN. Other Natrargids that have an exchangeable sodium

percentage of less than 15 (or an SAR of less than 13) in 50

percent or more of the natric horizon.

Haplic Natrargids

GEBO. Other Natrargids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Natrargids

GEBP. Other Natrargids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Natrargids

GEBQ. Other Natrargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 oC or higher and have a soil moisture regime that borders on

xeric.

Xeric Natrargids

GEBR. Other Natrargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

ustic.

Ustic Natrargids

GEBS. Other Natrargids that have skeletans covering 10

percent or more of the surfaces of peds at a depth 2.5 cm or

more below the upper boundary of the natric horizon.

Glossic Natrargids

GEBT. Other Natrargids.

Typic Natrargids
104 Keys to Soil Taxonomy

Paleargids

Key to Subgroups

GECA. Paleargids that have one or both of the following:

1. Cracks within 125 cm of the soil surface that are

5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Vertic Paleargids

GECB. Other Paleargids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within 100

cm of the soil surface for 1 month or more in normal years.

Aquic Paleargids

GECC. Other Paleargids that have:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 cm or more; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Arenic Ustic Paleargids

GECD. Other Paleargids that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 cm or more.

Arenic Paleargids

GECE. Other Paleargids that have a calcic horizon that has its

upper boundary within 150 cm of the soil surface.

Calcic Paleargids

GECF. Other Paleargids that have:

1. One or more horizons, within 100 cm of the soil surface

and with a combined thickness of 15 cm or more, that

contain 20 percent or more (by volume) durinodes or are

brittle and have at least a firm rupture-resistance class when

moist; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Durinodic Xeric Paleargids

GECG. Other Paleargids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes or are brittle and have at least a firm ruptureresistance class when moist.

Durinodic Paleargids

GECH. Other Paleargids that:

1. Have one or more horizons, within 100 cm of the soil

surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) nodules or

concretions; and

2. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and have a

soil moisture regime that borders on ustic.

Petronodic Ustic Paleargids

GECI. Other Paleargids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) nodules or concretions.

Petronodic Paleargids

GECJ. Other Paleargids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Paleargids

GECK. Other Paleargids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser
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than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Paleargids

GECL. Other Paleargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Paleargids

GECM. Other Paleargids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Paleargids

GECN. Other Paleargids.

Typic Paleargids

Petroargids

Key to Subgroups

GEAA. Petroargids that meet both of the following:

1. Have a petrogypsic horizon that has its upper boundary

within 150 cm of the soil surface; and

2. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature is 5 oC or higher at a depth of 50 cm and have a

soil moisture regime that borders on ustic.

Petrogypsic Ustic Petroargids

GEAB. Other Petroargids that have a petrogypsic horizon that

has its upper boundary within 150 cm of the soil surface.

Petrogypsic Petroargids

GEAC. Other Petroargids that have:

1. A duripan that has its upper boundary within 150 cm of

the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Duric Xeric Petroargids

GEAD. Other Petroargids that have a duripan that has its

upper boundary within 150 cm of the soil surface.

Duric Petroargids

GEAE. Other Petroargids that have a natric horizon.

Natric Petroargids

GEAF. Other Petroargids that have a moisture control section

that is dry in all parts for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Petroargids

GEAG. Other Petroargids that have a moisture control section

that is dry in all parts for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Petroargids

GEAH. Other Petroargids.

Typic Petroargids

Calcids

Key to Great Groups

GFA. Calcids that have a petrocalcic horizon that has its upper

boundary within 100 cm of the soil surface.

Petrocalcids, p. 107

GFB. Other Calcids.

Haplocalcids, p. 105

Haplocalcids

Key to Subgroups

GFBA. Haplocalcids that have:

1. A lithic contact within 50 cm of the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 oC or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Lithic Xeric Haplocalcids

GFBB. Other Haplocalcids that have:

1. A lithic contact within 50 cm of the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil
106 Keys to Soil Taxonomy

temperature is 5 oC or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Lithic Ustic Haplocalcids

GFBC. Other Haplocalcids that have a lithic contact within 50

cm of the soil surface.

Lithic Haplocalcids

GFBD. Other Haplocalcids that have:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide through a thickness of 30 cm or more for some

time in normal years and slickensides or wedge-shaped

aggregates in a layer 15 cm or more thick that has its upper

boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Vertic Haplocalcids

GFBE. Other Haplocalcids that:

1. Are either:

a. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the

soil surface; or

b. Saturated with water in one or more layers within 100

cm of the soil surface for 1 month or more in normal

years; and

2. Have one or more horizons, within 100 cm of the soil

surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) durinodes or are

brittle and have at least a firm rupture-resistance class when

moist.

Aquic Durinodic Haplocalcids

GFBF. Other Haplocalcids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within

100 cm of the soil surface for 1 month or more in normal

years.

Aquic Haplocalcids

GFBG. Other Haplocalcids that have:

1. A duripan that has its upper boundary within 150 cm of

the surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Duric Xeric Haplocalcids

GFBH. Other Haplocalcids that have a duripan that has its

upper boundary within 150 cm of the surface.

Duric Haplocalcids

GFBI. Other Haplocalcids that have:

1. One or more horizons, within 100 cm of the soil surface

and with a combined thickness of 15 cm or more, that

contain 20 percent or more (by volume) durinodes or are

brittle and have at least a firm rupture-resistance class when

moist; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Durinodic Xeric Haplocalcids

GFBJ. Other Haplocalcids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes or are brittle and have at least a firm ruptureresistance class when moist.

Durinodic Haplocalcids

GFBK. Other Haplocalcids that have:

1. One or more horizons, within 100 cm of the soil surface

and with a combined thickness of 15 cm or more, that

contain 20 percent or more (by volume) nodules or

concretions; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Petronodic Xeric Haplocalcids

GFBL. Other Haplocalids that:

1. Have one or more horizons, within 100 cm of the soil

surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) nodules or

concretions; and

2. Are dry in all parts of the moisture control section

for less than three-fourths of the time (cumulative)

when the soil temperature at a depth of 50 cm is 5 o

C or

higher and have a soil moisture regime that borders on ustic.

Petronodic Ustic Haplocalcids

GFBM. Other Haplocalcids that have one or more horizons,
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within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) nodules or concretions.

Petronodic Haplocalcids

GFBN. Other Haplocalcids that have both:

1. A horizon at least 25 cm thick within 100 cm of the soil

surface that has an exchangeable sodium percentage of 15 or

more (or an SAR of 13 or more) during at least 1 month in

normal years; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and a soil

moisture regime that borders on xeric.

Sodic Xeric Haplocalcids

GFBO. Other Haplocalcids that meet both of the following:

1. Have, in a horizon at least 25 cm thick within 100 cm of

the soil surface, an exchangeable sodium percentage of 15 or

more (or an SAR of 13 or more) during at least 1 month in

normal years; and

2. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and have a

soil moisture regime that borders on ustic.

Sodic Ustic Haplocalcids

GFBP. Other Haplocalcids that have, in a horizon at least 25

cm thick within 100 cm of the mineral soil surface, an

exchangeable sodium percentage of 15 or more (or an SAR of

13 or more) during at least 1 month in normal years.

Sodic Haplocalcids

GFBQ. Other Haplocalcids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Haplocalcids

GFBR. Other Haplocalcids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Haplocalcids

GFBS. Other Haplocalcids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Haplocalcids

GFBT. Other Haplocalcids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Haplocalcids

GFBU. Other Haplocalcids.

Typic Haplocalcids

Petrocalcids

Key to Subgroups

GFAA. Petrocalcids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within

100 cm of the soil surface for 1 month or more in normal

years.

Aquic Petrocalcids

GFAB. Other Petrocalcids that have a natric horizon.

Natric Petrocalcids

GFAC. Other Petrocalcids that have both of the following:

1. An argillic horizon that has its upper boundary within

100 cm of the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil
108 Keys to Soil Taxonomy

temperature is 5 oC or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Xeralfic Petrocalcids

GFAD. Other Petrocalcids that have both of the following:

1. An argillic horizon that has its upper boundary within

100 cm of the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Ustalfic Petrocalcids

GFAE. Other Petrocalcids that have an argillic horizon that

has its upper boundary within 100 cm of the soil surface.

Argic Petrocalcids

GFAF. Other Petrocalcids that have:

1. A calcic horizon overlying the petrocalcic horizon; and

2. A lithic contact within 50 cm of the soil surface.

Calcic Lithic Petrocalcids

GFAG. Other Petrocalcids that have a calcic horizon

overlying the petrocalcic horizon.

Calcic Petrocalcids

GFAH. Other Petrocalcids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Petrocalcids

GFAI. Other Petrocalcids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Petrocalcids

GFAJ. Other Petrocalcids.

Typic Petrocalcids

Cambids

Key to Great Groups

GGA. Cambids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within

100 cm of the soil surface for 1 month or more in normal

years.

Aquicambids, p. 108

GGB. Other Cambids that have a duripan or a petrocalcic or

petrogypsic horizon that has its upper boundary within 150 cm

of the soil surface.

Petrocambids, p. 111

GGC. Other Cambids that have an anthropic epipedon.

Anthracambids, p. 108

GGD. Other Cambids.

Haplocambids, p. 109

Anthracambids

Key to Subgroups

GGCA. All Anthracambids.

Typic Anthracambids

Aquicambids

Key to Subgroups

GGAA. Aquicambids that have, in a horizon at least 25 cm

thick within 100 cm of the soil surface, an exchangeable

sodium percentage of 15 or more (or an SAR of 13 or more)

during at least 1 month in normal years.

Sodic Aquicambids

GGAB. Other Aquicambids that:

1. Have one or more horizons, within 100 cm of the soil

surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) durinodes or are

brittle and have at least a firm rupture-resistance class when

moist; and

2. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and have a

soil moisture regime that borders on xeric.

Durinodic Xeric Aquicambids

GGAC. Other Aquicambids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes or are brittle and have at least a firm ruptureresistance class when moist.

Durinodic Aquicambids

GGAD. Other Aquicambids that have one or more horizons,

within 100 cm of the soil surface and with a combined
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thickness of 15 cm or more, that contain 20 percent or more (by

volume) nodules or concretions.

Petronodic Aquicambids

GGAE. Other Aquicambids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Aquicambids

GGAF. Other Aquicambids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Aquicambids

GGAG. Other Aquicambids that have an irregular decrease in

content of organic carbon from a depth of 25 cm either to a

depth of 125 cm or to a densic, lithic, or paralithic contact if

shallower.

Fluventic Aquicambids

GGAH. Other Aquicambids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Aquicambids

GGAI. Other Aquicambids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Aquicambids

GGAJ. Other Aquicambids.

Typic Aquicambids

Haplocambids

Key to Subgroups

GGDA. Haplocambids that have:

1. A lithic contact within 50 cm of the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 oC or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Lithic Xeric Haplocambids

GGDB. Other Haplocambids that have:

1. A lithic contact within 50 cm of the soil surface; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Lithic Ustic Haplocambids

GGDC. Other Haplocambids that have a lithic contact within

50 cm of the soil surface.

Lithic Haplocambids

GGDD. Other Haplocambids that have:

1. One or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or

b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact if shallower; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Xerertic Haplocambids

GGDE. Other Haplocambids that have:

1. One or both of the following:

a. Cracks within 125 cm of the soil surface that are 5
110 Keys to Soil Taxonomy

mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or

b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact if shallower; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 oC or higher at a depth of 50 cm and a soil

moisture regime that borders on ustic.

Ustertic Haplocambids

GGDF. Other Haplocambids that have at least one of the

following:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide through a thickness of 30 cm or more for some

time in normal years and slickensides or wedge-shaped

aggregates in a layer 15 cm or more thick that has its upper

boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Vertic Haplocambids

GGDG. Other Haplocambids that have both of the following:

1. One or more horizons, within 100 cm of the soil surface

and with a combined thickness of 15 cm or more, that

contain 20 percent or more (by volume) durinodes or are

brittle and have at least a firm rupture-resistance class when

moist; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and a soil

moisture regime that borders on xeric.

Durinodic Xeric Haplocambids

GGDH. Other Haplocambids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes or are brittle and have at least a firm ruptureresistance class when moist.

Durinodic Haplocambids

GGDI. Other Haplocambids that have:

1. One or more horizons, within 100 cm of the soil surface

and with a combined thickness of 15 cm or more, that

contain 20 percent or more (by volume) nodules or

concretions; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and a soil

moisture regime that borders on xeric.

Petronodic Xeric Haplocambids

GGDJ. Other Haplocambids that:

1. Have one or more horizons, within 100 cm of the soil

surface and with a combined thickness of 15 cm or more,

that contain 20 percent or more (by volume) nodules or

concretions; and

2. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and have a

soil moisture regime that borders on ustic.

Petronodic Ustic Haplocambids

GGDK. Other Haplocambids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) nodules or concretions.

Petronodic Haplocambids

GGDL. Other Haplocambids that have both:

1. A horizon at least 25 cm thick within 100 cm of the soil

surface that has an exchangeable sodium percentage of 15 or

more (or an SAR of 13 or more) during at least 1 month in

normal years; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and a soil

moisture regime that borders on xeric.

Sodic Xeric Haplocambids

GGDM. Other Haplocambids that meet both of the following:

1. Have, in a horizon at least 25 cm thick within 100 cm of

the soil surface, an exchangeable sodium percentage of 15 or

more (or an SAR of 13 or more) during at least 1 month in

normal years; and

2. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and have a

soil moisture regime that borders on ustic.

Sodic Ustic Haplocambids

GGDN. Other Haplocambids that have, in a horizon at least

25 cm thick within 100 cm of the soil surface, an exchangeable

sodium percentage of 15 or more (or an SAR of 13 or more)

during at least 1 month in normal years.

Sodic Haplocambids

GGDO. Other Haplocambids that have both:
Aridisols 111

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1. A moisture control section that is dry in all parts

for less than three-fourths of the time (cumulative) when the

soil temperature is 5 oC or higher at a depth of 50 cm and a

soil moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Haplocambids

GGDP. Other Haplocambids that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Haplocambids

GGDQ. Other Haplocambids that:

1. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and have a

soil moisture regime that borders on xeric; and

2. Have an irregular decrease in content of organic carbon

from a depth of 25 cm either to a depth of 125 cm or to a

densic, lithic, or paralithic contact if shallower.

Xerofluventic Haplocambids

GGDR. Other Haplocambids that:

1. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature at a depth of 50 cm is 5 o

C or higher and have a

soil moisture regime that borders on ustic; and

2. Have an irregular decrease in content of organic carbon

from a depth of 25 cm either to a depth of 125 cm or to a

densic, lithic, or paralithic contact if shallower.

Ustifluventic Haplocambids

GGDS. Other Haplocambids that have an irregular decrease

in content of organic carbon from a depth of 25 cm either to a

depth of 125 cm or to a densic, lithic, or paralithic contact if

shallower.

Fluventic Haplocambids

GGDT. Other Haplocambids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

xeric.

Xeric Haplocambids

GGDU. Other Haplocambids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

ustic.

Ustic Haplocambids

GGDV. Other Haplocambids.

Typic Haplocambids

Petrocambids

Key to Subgroups

GGBA. Petrocambids that have, in a horizon at least 25 cm

thick within 100 cm of the soil surface, an exchangeable

sodium percentage of 15 or more (or an SAR of 13 or more)

during at least 1 month in normal years.

Sodic Petrocambids

GGBB. Other Petrocambids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Petrocambids

GGBC. Other Petrocambids that have, throughout one or
112 Keys to Soil Taxonomy

more horizons with a total thickness of 18 cm or more within

75 cm of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Petrocambids

GGBD. Other Petrocambids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

xeric.

Xeric Petrocambids

GGBE. Other Petrocambids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

ustic.

Ustic Petrocambids

GGBF. Other Petrocambids.

Typic Petrocambids

Cryids

Key to Great Groups

GAA. Cryids that have a salic horizon that has its upper

boundary within 100 cm of the soil surface.

Salicryids, p. 115

GAB. Other Cryids that have a duripan or a petrocalcic or

petrogypsic horizon that has its upper boundary within 100 cm

of the soil surface.

Petrocryids, p. 114

GAC. Other Cryids that have a gypsic horizon that has its

upper boundary within 100 cm of the soil surface.

Gypsicryids, p. 113

GAD. Other Cryids that have an argillic or natric horizon.

Argicryids, p. 112

GAE. Other Cryids that have a calcic horizon that has its

upper boundary within 100 cm of the soil surface.

Calcicryids, p. 113

GAF. Other Cryids.

Haplocryids, p. 114

Argicryids

Key to Subgroups

GADA. Argicryids that have a lithic contact within 50 cm of

the soil surface.

Lithic Argicryids

GADB. Other Argicryids that have one or both of the

following:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide throughout a thickness of 30 cm or more for

some time in normal years and slickensides or wedge-shaped

aggregates in a layer 15 cm or more thick that has its upper

boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Argicryids

GADC. Other Argicryids that have a natric horizon that has its

upper boundary within 100 cm of the soil surface.

Natric Argicryids

GADD. Other Argicryids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Argicryids

GADE. Other Argicryids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or
Aridisols 113

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2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Argicryids

GADF. Other Argicryids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Argicryids

GADG. Other Argicryids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Argicryids

GADH. Other Argicryids.

Typic Argicryids

Calcicryids

Key to Subgroups

GAEA. Calcicryids that have a lithic contact within 50 cm of

the soil surface.

Lithic Calcicryids

GAEB. Other Calcicryids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Calcicryids

GAEC. Other Calcicryids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Calcicryids

GAED. Other Calcicryids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Calcicryids

GAEE. Other Calcicryids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Calcicryids

GAEF. Other Calcicryids.

Typic Calcicryids

Gypsicryids

Key to Subgroups

GACA. Gypsicryids that have a calcic horizon.

Calcic Gypsicryids

GACB. Other Gypsicryids that have both:

1. A moisture control section that is dry in all parts

for less than three-fourths of the time (cumulative)

when the soil temperature is 5 o

C or higher at a depth

of 50 cm and a soil moisture regime that borders on xeric;

and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1

/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Gypsicryids
114 Keys to Soil Taxonomy

GACC. Other Gypsicryids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Gypsicryids

GACD. Other Gypsicryids.

Typic Gypsicryids

Haplocryids

Key to Subgroups

GAFA. Haplocryids that have a lithic contact within 50 cm of

the soil surface.

Lithic Haplocryids

GAFB. Other Haplocryids that have one or both of the

following:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide throughout a thickness of 30 cm or more for

some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the mineral soil surface;

or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Haplocryids

GAFC. Other Haplocryids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Haplocryids

GAFD. Other Haplocryids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Haplocryids

GAFE. Other Haplocryids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Haplocryids

GAFF. Other Haplocryids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Haplocryids

GAFG. Other Haplocryids.

Typic Haplocryids

Petrocryids

Key to Subgroups

GABA. Petrocryids that:

1. Have a duripan that is strongly cemented or less

cemented in all subhorizons and has its upper boundary

within 100 cm of the soil surface; and

2. Are dry in all parts of the moisture control section for

less than three-fourths of the time (cumulative) when the soil

temperature is 5 oC or higher at a depth of 50 cm and have a

soil moisture regime that borders on xeric.

Xereptic Petrocryids

GABB. Other Petrocryids that:

1. Have a duripan that has its upper boundary within 100

cm of the soil surface; and

2. Are dry in all parts of the moisture control section for
Aridisols 115

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less than three-fourths of the time (cumulative) when the soil

temperature is 5 oC or higher at a depth of 50 cm and have a

soil moisture regime that borders on xeric.

Duric Xeric Petrocryids

GABC. Other Petrocryids that have a duripan that has its

upper boundary within 100 cm of the soil surface.

Duric Petrocryids

GABD. Other Petrocryids that have a petrogypsic horizon

that has its upper boundary within 100 cm of the soil

surface.

Petrogypsic Petrocryids

GABE. Other Petrocryids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Petrocryids

GABF. Other Petrocryids that are dry in all parts of the

moisture control section for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

ustic.

Ustic Petrocryids

GABG. Other Petrocryids.

Typic Petrocryids

Salicryids

Key to Subgroups

GAAA. Salicryids that are saturated with water in one or

more layers within 100 cm of the soil surface for 1 month or

more in normal years.

Aquic Salicryids

GAAB. Other Salicryids.

Typic Salicryids

Durids

Key to Great Groups

GCA. Durids that have a natric horizon above the

duripan.

Natridurids, p. 117

GCB. Other Durids that have an argillic horizon above the

duripan.

Argidurids, p. 115

GCC. Other Durids.

Haplodurids, p. 116

Argidurids

Key to Subgroups

GCBA. Argidurids that have, above the duripan, one or both

of the following:

1. Cracks between the soil surface and the top of the

duripan that are 5 mm or more wide through a thickness of

30 cm or more for some time in normal years and

slickensides or wedge-shaped aggregates in a layer 15 cm or

more thick that has its upper boundary above the duripan; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and the top of the duripan.

Vertic Argidurids

GCBB. Other Argidurids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within

100 cm of the soil surface for 1 month or more in normal

years.

Aquic Argidurids

GCBC. Other Argidurids that have the following combination

of characteristics:

1. An argillic horizon that has 35 percent or more clay in

the fine-earth fraction of some part; and either

a. A clay increase of 15 percent or more (absolute)

within a vertical distance of 2.5 cm either within the

argillic horizon or at its upper boundary; or

b. If there is an Ap horizon directly above the argillic

horizon, a clay increase of 10 percent or more (absolute)

at the upper boundary of the argillic horizon; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Abruptic Xeric Argidurids

GCBD. Other Argidurids that have an argillic horizon that has

35 percent or more clay in the fine-earth fraction of some part;

and either

1. A clay increase of 15 percent or more (absolute) within

a vertical distance of 2.5 cm within the argillic horizon or at

its upper boundary; or

2. If there is an Ap horizon directly above the argillic
116 Keys to Soil Taxonomy

horizon, a clay increase of 10 percent or more (absolute) at

the upper boundary of the argillic horizon.

Abruptic Argidurids

GCBE. Other Argidurids that have:

1. A duripan that is strongly cemented or less cemented in

all subhorizons; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Haploxeralfic Argidurids

GCBF. Other Argidurids that have a duripan that is strongly

cemented or less cemented in all subhorizons.

Argidic Argidurids

GCBG. Other Argidurids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Argidurids

GCBH. Other Argidurids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Argidurids

GCBI. Other Argidurids that have a moisture control section

that is dry in all parts for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a

depth of 50 cm and have a soil moisture regime that borders on

xeric.

Xeric Argidurids

GCBJ. Other Argidurids that have a moisture control section

that is dry in all parts for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

ustic.

Ustic Argidurids

GCBK. Other Argidurids.

Typic Argidurids

Haplodurids

Key to Subgroups

GCCA. Haplodurids that:

1. Have a duripan that is strongly cemented or less

cemented in all subhorizons; and

2. Are either:

a. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the

soil surface; or

b. Saturated with water in one or more layers within 100

cm of the soil surface for 1 month or more in normal

years.

Aquicambidic Haplodurids

GCCB. Other Haplodurids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within

100 cm of the soil surface for 1 month or more in normal

years.

Aquic Haplodurids

GCCC. Other Haplodurids that have:

1. A duripan that is strongly cemented or less cemented in

all subhorizons; and

2. A mean annual soil temperature lower than 22 o

C, a

difference of 5 oC or more between mean summer and mean

winter soil temperatures at a depth of 50 cm, and a soil

moisture regime that borders on xeric.

Xereptic Haplodurids
Aridisols 117

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GCCD. Other Haplodurids that have a duripan that is strongly

cemented or less cemented in all subhorizons.

Cambidic Haplodurids

GCCE. Other Haplodurids that have:

1. A moisture control section that is dry in all parts for

three-fourths of the time (cumulative) or less when the soil

temperature at a depth of 50 cm is 5 o

C or higher and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Haplodurids

GCCF. Other Haplodurids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Haplodurids

GCCG. Other Haplodurids that have a mean annual soil

temperature lower than 22 oC, a difference of 5 oC or more

between mean summer and mean winter soil temperatures at

a depth of 50 cm, and a soil moisture regime that borders on

xeric.

Xeric Haplodurids

GCCH. Other Haplodurids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm

is 5 o

C or higher and have a soil moisture regime that borders

on ustic.

Ustic Haplodurids

GCCI. Other Haplodurids.

Typic Haplodurids

Natridurids

Key to Subgroups

GCAA. Natridurids that have, above the duripan, one or both

of the following:

1. Cracks between the soil surface and the top of the

duripan that are 5 mm or more wide through a thickness of

30 cm or more for some time in normal years and

slickensides or wedge-shaped aggregates in a layer 15 cm

or more thick that has its upper boundary above the duripan;

or

2. A linear extensibility of 6.0 cm or more between the soil

surface and the top of the duripan.

Vertic Natridurids

GCAB. Other Natridurids that meet both of the following:

1. Have a duripan that is strongly cemented or less

cemented in all subhorizons; and

2. Are either:

a. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the

soil surface; or

b. Saturated with water in one or more layers within

100 cm of the soil surface for 1 month or more in normal

years.

Aquic Natrargidic Natridurids

GCAC. Other Natridurids that are either:

1. Irrigated and have aquic conditions for some time in

normal years in one or more layers within 100 cm of the soil

surface; or

2. Saturated with water in one or more layers within 100

cm of the soil surface for 1 month or more in normal years.

Aquic Natridurids

GCAD. Other Natridurids that have the following

combination of characteristics:

1. A duripan that is strongly cemented or less cemented in

all subhorizons; and

2. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric.

Natrixeralfic Natridurids
118 Keys to Soil Taxonomy

GCAE. Other Natridurids that have a duripan that is strongly

cemented or less cemented in all subhorizons.

Natrargidic Natridurids

GCAF. Other Natridurids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Natridurids

GCAG. Other Natridurids that have, throughout one

or more horizons with a total thickness of 18 cm or more within

75 cm of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Natridurids

GCAH. Other Natridurids that have a moisture control section

that is dry in all parts for less than three-fourths of the time

(cumulative) when the soil temperature is 5 o

C or higher at a depth

of 50 cm and have a soil moisture regime that borders on xeric.

Xeric Natridurids

GCAI. Other Natridurids.

Typic Natridurids

Gypsids

Key to Great Groups

GDA. Gypsids that have a petrogypsic or petrocalcic horizon

that has its upper boundary within 100 cm of the soil surface.

Petrogypsids, p. 121

GDB. Other Gypsids that have a natric horizon that has its

upper boundary within 100 cm of the soil surface.

Natrigypsids, p. 120

GDC. Other Gypsids that have an argillic horizon that has its

upper boundary within 100 cm of the soil surface.

Argigypsids, p. 118

GDD. Other Gypsids that have a calcic horizon that has its

upper boundary within 100 cm of the soil surface.

Calcigypsids, p. 119

GDE. Other Gypsids.

Haplogypsids, p. 120

Argigypsids

Key to Subgroups

GDCA. Argigypsids that have a lithic contact within 50 cm of

the soil surface.

Lithic Argigypsids

GDCB. Other Argigypsids that have:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide through a thickness of 30 cm or more for some

time in normal years and slickensides or wedge-shaped

aggregates in a layer 15 cm or more thick that has its upper

boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Vertic Argigypsids

GDCC. Other Argigypsids that have a calcic horizon

overlying the gypsic horizon.

Calcic Argigypsids

GDCD. Other Argigypsids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes, nodules, or concretions.

Petronodic Argigypsids

GDCE. Other Argigypsids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser
Aridisols 119

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than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Argigypsids

GDCF. Other Argigypsids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 percent or more.

Vitrandic Argigypsids

GDCG. Other Argigypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

xeric.

Xeric Argigypsids

GDCH. Other Argigypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

ustic.

Ustic Argigypsids

GDCI. Other Argigypsids.

Typic Argigypsids

Calcigypsids

Key to Subgroups

GDDA. Calcigypsids that have a lithic contact within 50 cm

of the soil surface.

Lithic Calcigypsids

GDDB. Other Calcigypsids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes, nodules, or concretions.

Petronodic Calcigypsids

GDDC. Other Calcigypsids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Calcigypsids

GDDD. Other Calcigypsids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Calcigypsids

GDDE. Other Calcigypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm

is 5 oC or higher and have a soil moisture regime that borders

on xeric.

Xeric Calcigypsids

GDDF. Other Calcigypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm is

5 o

C or higher and have a soil moisture regime that borders on

ustic.

Ustic Calcigypsids

GDDG. Other Calcigypsids.

Typic Calcigypsids
120 Keys to Soil Taxonomy

Haplogypsids

Key to Subgroups

GDEA. Haplogypsids that have a lithic contact within 50 cm

of the soil surface.

Lithic Haplogypsids

GDEB. Other Haplogypsids that have a gypsic horizon

that has its upper boundary within 18 cm of the soil

surface.

Leptic Haplogypsids

GDEC. Other Haplogypsids that have, in a horizon at least

25 cm thick within 100 cm of the mineral soil surface, an

exchangeable sodium percentage of 15 or more (or an SAR of

13 or more) during at least 1 month in normal years.

Sodic Haplogypsids

GDED. Other Haplogypsids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes, nodules, or concretions.

Petronodic Haplogypsids

GDEE. Other Haplogypsids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Haplogypsids

GDEF. Other Haplogypsids that have, throughout one

or more horizons with a total thickness of 18 cm or more within

75 cm of the soil surface, one or both of the

following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Haplogypsids

GDEG. Other Haplogypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the time

(cumulative) when the soil temperature at a depth of 50 cm is 5 o

C

or higher and have a soil moisture regime that borders on xeric.

Xeric Haplogypsids

GDEH. Other Haplogypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm

is 5 o

C or higher and have a soil moisture regime that borders

on ustic.

Ustic Haplogypsids

GDEI. Other Haplogypsids.

Typic Haplogypsids

Natrigypsids

Key to Subgroups

GDBA. Natrigypsids that have a lithic contact within 50 cm

of the soil surface.

Lithic Natrigypsids

GDBB. Other Natrigypsids that have:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide through a thickness of 30 cm or more for some

time in normal years and slickensides or wedge-shaped

aggregates in a layer 15 cm or more thick that has its upper

boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Vertic Natrigypsids

GDBC. Other Natrigypsids that have one or more horizons,

within 100 cm of the soil surface and with a combined

thickness of 15 cm or more, that contain 20 percent or more (by

volume) durinodes, nodules, or concretions.

Petronodic Natrigypsids

GDBD. Other Natrigypsids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil
Aridisols 121

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temperature is 5 oC or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Natrigypsids

GDBE. Other Natrigypsids that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Natrigypsids

GDBF. Other Natrigypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm

is 5 o

C or higher and have a soil moisture regime that borders

on xeric.

Xeric Natrigypsids

GDBG. Other Natrigypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm

is 5 o

C or higher and have a soil moisture regime that borders

on ustic.

Ustic Natrigypsids

GDBH. Other Natrigypsids.

Typic Natrigypsids

Petrogypsids

Key to Subgroups

GDAA. Petrogypsids that have a petrocalcic horizon that has

its upper boundary within 100 cm of the soil surface.

Petrocalcic Petrogypsids

GDAB. Other Petrogypsids that have a calcic horizon

overlying the petrogypsic horizon.

Calcic Petrogypsids

GDAC. Other Petrogypsids that have both:

1. A moisture control section that is dry in all parts for less

than three-fourths of the time (cumulative) when the soil

temperature is 5 o

C or higher at a depth of 50 cm and a soil

moisture regime that borders on xeric; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent

or more is volcanic glass, and [(Al plus 1/2 Fe, percent

extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrixerandic Petrogypsids

GDAD. Other Petrogypsids that have, throughout one

or more horizons with a total thickness of 18 cm or more within

75 cm of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is 30 or more.

Vitrandic Petrogypsids

GDAE. Other Petrogypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm

is 5 o

C or higher and have a soil moisture regime that borders

on xeric.

Xeric Petrogypsids

GDAF. Other Petrogypsids that have a moisture control

section that is dry in all parts for less than three-fourths of the

time (cumulative) when the soil temperature at a depth of 50 cm

is 5 o

C or higher and have a soil moisture regime that borders

on ustic.

Ustic Petrogypsids

GDAG. Other Petrogypsids.

Typic Petrogypsids
122

Salids

Key to Great Groups

GBA. Salids that are saturated with water in one or more

layers within 100 cm of the mineral soil surface for 1 month or

more in normal years.

Aquisalids, p. 122

GBB. Other Salids.

Haplosalids, p. 122

Aquisalids

Key to Subgroups

GBAA. Aquisalids that have a gypsic or petrogypsic

horizon that has its upper boundary within 100 cm of the soil

surface.

Gypsic Aquisalids

GBAB. Other Aquisalids that have a calcic or petrocalcic

horizon that has an upper boundary within 100 cm of the soil

surface.

Calcic Aquisalids

GBAC. Other Aquisalids.

Typic Aquisalids

Haplosalids

Key to Subgroups

GBBA. Haplosalids that have a duripan that has its upper

boundary within 100 cm of the soil surface.

Duric Haplosalids

GBBB. Other Haplosalids that have a petrogypsic horizon

that has its upper boundary within 100 cm of the soil surface.

Petrogypsic Haplosalids

GBBC. Other Haplosalids that have a gypsic horizon that has

its upper boundary within 100 cm of the soil surface.

Gypsic Haplosalids

GBBD. Other Haplosalids that have a calcic horizon that has

its upper boundary within 100 cm of the soil surface.

Calcic Haplosalids

GBBE. Other Haplosalids.

Typic Haplosalids
123

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Key to Suborders

LA. Entisols that have one or more of the following:

1. Aquic conditions and sulfidic materials within 50 cm of

the mineral soil surface; or

2. Permanent saturation with water and a reduced matrix

in all horizons below 25 cm from the mineral soil surface;

or

3. In a layer above a densic, lithic, or paralithic contact or

in a layer at a depth between 40 and 50 cm below the

mineral soil surface, whichever is shallower, aquic

conditions for some time in normal years (or artificial

drainage) and one or more of the following:

a. A texture finer than loamy fine sand and, in 50 percent

or more of the matrix, one or more of the following:

(1) Chroma of 0; or

(2) Chroma of 1 or less and a color value, moist, of 4

or more; or

(3) Chroma of 2 or less and redox concentrations; or

b. A texture of loamy fine sand or coarser and, in 50

percent or more of the matrix, one or more of the

following:

(1) Chroma of 0; or

(2) Hue of 10YR or redder, a color value, moist, of 4

or more, and chroma of 1; or

(3) Hue of 10YR or redder, chroma of 2 or less, and

redox concentrations; or

(4) Hue of 2.5Y or yellower, chroma of 3 or less, and

distinct or prominent redox concentrations; or

(5) Hue of 2.5Y or yellower and chroma of 1; or

(6) Hue of 5GY, 5G, 5BG, or 5B; or

(7) Any color if it results from uncoated sand grains;

or

c. Enough active ferrous iron to give a positive reaction

to alpha,alpha-dipyridyl at a time when the soil is not

being irrigated.

Aquents, p. 123

LB. Other Entisols that have, in one or more layers at a depth

between 25 and 100 cm below the mineral soil surface, 3

percent or more (by volume) fragments of diagnostic horizons

that are not arranged in any discernible order.

Arents, p. 127

LC. Other Entisols that have less than 35 percent (by volume)

rock fragments and a texture of loamy fine sand or coarser in all

layers (sandy loam lamellae are permitted) within the particlesize control section.

Psamments, p. 139

LD. Other Entisols that do not have a densic, lithic, or

paralithic contact within 25 cm of the mineral soil surface

and have:

1. A slope of less than 25 percent; and

2. Either 0.2 percent or more organic carbon of Holocene

age at a depth of 125 cm below the mineral soil surface or an

irregular decrease in content of organic carbon from a depth

of 25 cm to a depth of 125 cm or to a densic, lithic, or

paralithic contact if shallower; and

3. A soil temperature regime:

a. That is warmer than cryic; or

b. That is cryic and the soil has:

(1) No gelic material; and

(2) Either a slope of less than 5 percent or less than

15 percent volcanic glass in the 0.02 to 2.0 mm

fraction in some part of the particle-size control

section.

Fluvents, p. 128

LE. Other Entisols.

Orthents, p. 133

Aquents

Key to Great Groups

LAA. Aquents that have sulfidic materials within 50 cm of the

mineral soil surface.

Sulfaquents, p. 127

CHAPTER 8

Entisols
124 Keys to Soil Taxonomy

LAB. Other Aquents that have, in all horizons at a depth

between 20 and 50 cm below the mineral soil surface, both an n

value of more than 0.7 and 8 percent or more clay in the fineearth fraction.

Hydraquents, p. 126

LAC. Other Aquents that have, in normal years, a mean

annual soil temperature of 0 o

C or colder and a mean summer

soil temperature that:

1. Is 8 oC or colder if there is no O horizon; or

2. Is 5 oC or colder if there is an O horizon.

Gelaquents, p. 126

LAD. Other Aquents that have a cryic soil temperature

regime.

Cryaquents, p. 124

LAE. Other Aquents that have less than 35 percent (by

volume) rock fragments and a texture of loamy fine sand or

coarser in all layers (sandy loam lamellae are permitted) within

the particle-size control section.

Psammaquents, p. 126

LAF. Other Aquents that have either 0.2 percent or more

organic carbon of Holocene age at a depth of 125 cm below the

mineral soil surface or an irregular decrease in content of

organic carbon from a depth of 25 cm to a depth of 125 cm or

to a densic, lithic, or paralithic contact if shallower.

Fluvaquents, p. 125

LAG. Other Aquents that have episaturation.

Epiaquents, p. 125

LAH. Other Aquents.

Endoaquents, p. 124

Cryaquents

Key to Subgroups

LADA. Cryaquents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Cryaquents

LADB. Other Cryaquents.

Typic Cryaquents

Endoaquents

Key to Subgroups

LAHA. Endoaquents that have, within 100 cm of the mineral

soil surface, one or both of the following:

1. Sulfidic materials; or

2. A horizon 15 cm or more thick that has all of the

characteristics of a sulfuric horizon, except that it has a pH

value between 3.5 and 4.0.

Sulfic Endoaquents

LAHB. Other Endoaquents that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Endoaquents

LAHC. Other Endoaquents that have, in one or more horizons

within 100 cm of the mineral soil surface, an exchangeable

sodium percentage of 15 or more (or a sodium adsorption ratio

of 13 or more) for 6 or more months in normal years.

Sodic Endoaquents

LAHD. Other Endoaquents that have, in one or more horizons

between either the Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and a depth of 75 cm,

colors in 50 percent or more of the matrix as follows:

1. Hue of 2.5Y or redder, a color value, moist, of 6 or

more, and chroma of 3 or more; or

2. Hue of 2.5Y or redder, a color value, moist, of 5 or less,

and chroma of 2 or more; or

3. Hue of 5Y and chroma of 3 or more; or

4. Hue of 5Y or redder and chroma of 2 or more if there

are no redox concentrations.

Aeric Endoaquents

LAHE. Other Endoaquents that have both:

1. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 15 cm of the mineral soil, or materials between the

mineral soil surface and a depth of 15 cm have these color

values after mixing; and
Entisols 125

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2. A base saturation (by NH4OAc) of less than 50 percent

in some part within 100 cm of the mineral soil surface.

Humaqueptic Endoaquents

LAHF. Other Endoaquents that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Endoaquents

LAHG. Other Endoaquents.

Typic Endoaquents

Epiaquents

Key to Subgroups

LAGA. Epiaquents that have, in one or more horizons

between either the Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and a depth of 75 cm,

colors in 50 percent or more of the matrix as follows:

1. Hue of 2.5Y or redder, a color value, moist, of 6 or

more, and chroma of 3 or more; or

2. Hue of 2.5Y or redder, a color value, moist, of 5 or less,

and chroma of 2 or more; or

3. Hue of 5Y and chroma of 3 or more; or

4. Chroma of 2 or more if there are no redox

concentrations.

Aeric Epiaquents

LAGB. Other Epiaquents that have both:

1. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 15 cm of the mineral soil, or materials between the

mineral soil surface and a depth of 15 cm have these color

values after mixing; and

2. A base saturation (by NH4

OAc) of less than

50 percent in some part within 100 cm of the mineral soil

surface.

Humaqueptic Epiaquents

LAGC. Other Epiaquents that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Epiaquents

LAGD. Other Epiaquents.

Typic Epiaquents

Fluvaquents

Key to Subgroups

LAFA. Fluvaquents that have, within 100 cm of the mineral

soil surface, one or both of the following:

1. Sulfidic materials; or

2. A horizon 15 cm or more thick that has all of the

characteristics of a sulfuric horizon, except that it has a pH

value between 3.5 and 4.0.

Sulfic Fluvaquents

LAFB. Other Fluvaquents that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Fluvaquents

LAFC. Other Fluvaquents that have a buried layer of organic

soil materials, 20 cm or more thick, that has its upper boundary

within 100 cm of the mineral soil surface.

Thapto-Histic Fluvaquents

LAFD. Other Fluvaquents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and
126 Keys to Soil Taxonomy

2. A horizon 15 cm or more thick that has all of the

characteristics of a sulfuric horizon, except that it has a pH

value between 3.5 and 4.0.

Sulfic Hydraquents

LABB. Other Hydraquents that have, in one or more horizons

within 100 cm of the mineral soil surface, an exchangeable

sodium percentage of 15 or more (or a sodium adsorption ratio

of 13 or more) for 6 or more months in normal years.

Sodic Hydraquents

LABC. Other Hydraquents that have a buried layer of organic

soil materials, 20 cm or more thick, that has its upper boundary

within 100 cm of the mineral soil surface.

Thapto-Histic Hydraquents

LABD. Other Hydraquents.

Typic Hydraquents

Psammaquents

Key to Subgroups

LAEA. Psammaquents that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Psammaquents

LAEB. Other Psammaquents that have, in one or more

horizons within 100 cm of the mineral soil surface, an

exchangeable sodium percentage of 15 or more (or a sodium

adsorption ratio of 13 or more) for 6 or more months in normal

years.

Sodic Psammaquents

LAEC. Other Psammaquents that have a horizon, 5 cm or

more thick, either below an Ap horizon or at a depth of 18 cm

or more from the mineral soil surface, whichever is deeper, that

has one or more of the following:

1. In 25 percent or more of each pedon, cementation by

organic matter and aluminum, with or without iron; or

2. Al plus 1

/2 Fe percentages (by ammonium oxalate)

totaling 0.25 or more, and half that amount or less in an

overlying horizon; or

3. An ODOE value of 0.12 or more, and a value half as

high or lower in an overlying horizon.

Spodic Psammaquents

LAED. Other Psammaquents that have both:

1. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 15 cm of the mineral soil, or materials between the

mineral soil surface and a depth of 15 cm have these color

values after mixing; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Fluvaquents

LAFE. Other Fluvaquents that have, in one or more horizons

between either the Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and a depth of 75 cm,

colors in 50 percent or more of the matrix as follows:

1. Hue of 2.5Y or redder, a color value, moist, of 6 or

more, and chroma of 3 or more; or

2. Hue of 2.5Y or redder, a color value, moist, of 5 or less,

and chroma of 2 or more; or

3. Hue of 5Y and chroma of 3 or more; or

4. Chroma of 2 or more if there are no redox

concentrations.

Aeric Fluvaquents

LAFF. Other Fluvaquents that have both:

1. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 15 cm of the mineral soil, or materials between the

mineral soil surface and a depth of 15 cm have these color

values after mixing; and

2. A base saturation (by NH4

OAc) of less than 50 percent

in some part within 100 cm of the mineral soil surface.

Humaqueptic Fluvaquents

LAFG. Other Fluvaquents that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Fluvaquents

LAFH. Other Fluvaquents.

Typic Fluvaquents

Gelaquents

Key to Subgroups

LACA. All Gelaquents.

Typic Gelaquents

Hydraquents

Key to Subgroups

LABA. Hydraquents that have, within 100 cm of the mineral

soil surface, one or both of the following:

1. Sulfidic materials; or
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2. A base saturation (by NH4OAc) of less than 50

percent in some part within 100 cm of the mineral soil

surface.

Humaqueptic Psammaquents

LAEE. Other Psammaquents that have a color value, moist, of

3 or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Psammaquents

LAEF. Other Psammaquents.

Typic Psammaquents

Sulfaquents

Key to Subgroups

LAAA. Sulfaquents that have, in some horizons at a depth

between 20 and 50 cm below the mineral soil surface, either or

both:

1. An n value of 0.7 or less; or

2. Less than 8 percent clay in the fine-earth fraction.

Haplic Sulfaquents

LAAB. Other Sulfaquents that have a histic epipedon.

Histic Sulfaquents

LAAC. Other Sulfaquents that have a buried layer of organic

soil materials, 20 cm or more thick, that has its upper boundary

within 100 cm of the mineral soil surface.

Thapto-Histic Sulfaquents

LAAD. Other Sulfaquents.

Typic Sulfaquents

Arents

Key to Great Groups

LBA. Arents that have an ustic moisture regime.

Ustarents, p. 127

LBB. Other Arents that have a xeric moisture regime.

Xerarents, p. 128

LBC. Other Arents that have an aridic (or torric) moisture

regime.

Torriarents, p. 127

LBD. Other Arents.

Udarents, p. 127

Torriarents

Key to Subgroups

LBCA. Torriarents that have, in one or more horizons within

100 cm of the mineral soil surface, 3 percent or more fragments

of a natric horizon.

Sodic Torriarents

LBCB. Other Torriarents that have, within 100 cm of the

mineral soil surface, 3 percent or more fragments of a duripan

or a petrocalcic horizon;

Duric Torriarents

LBCC. Other Torriarents.

Haplic Torriarents

Udarents

Key to Subgroups

LBDA. Udarents that have 3 percent or more fragments of an

argillic horizon in some horizon within 100 cm of the mineral

soil surface and have a base saturation (by sum of cations) of 35

percent or more in all parts within 100 cm of the mineral soil

surface.

Alfic Udarents

LBDB. Other Udarents that have 3 percent or more fragments

of an argillic horizon in some horizon within 100 cm of the

mineral soil surface.

Ultic Udarents

LBDC. Other Udarents that have 3 percent or more fragments

of a mollic epipedon in some horizon within 100 cm of the

mineral soil surface and have a base saturation (by sum of

cations) of 35 percent or more in all parts within 100 cm of the

mineral soil surface.

Mollic Udarents

LBDD. Other Udarents.

Haplic Udarents

Ustarents

Key to Subgroups

LBAA. All Ustarents.

Haplic Ustarents
128 Keys to Soil Taxonomy

Xerarents

Key to Subgroups

LBBA. Xerarents that have, in one or more horizons within

100 cm of the mineral soil surface, 3 percent or more fragments

of a natric horizon.

Sodic Xerarents

LBBB. Other Xerarents that have, within 100 cm of the

mineral soil surface, 3 percent or more fragments of a duripan

or a petrocalcic horizon.

Duric Xerarents

LBBC. Other Xerarents that have fragments of an argillic

horizon with a base saturation (by sum of cations) of 35 percent

or more within 100 cm of the mineral soil surface.

Alfic Xerarents

LBBD. Other Xerarents.

Haplic Xerarents

Fluvents

Key to Great Groups

LDA. Fluvents that that have, in normal years, a mean annual

soil temperature of 0 oC or colder and a mean summer soil

temperature that:

1. Is 8 oC or colder if there is no O horizon; or

2. Is 5 oC or colder if there is an O horizon.

Gelifluvents, p. 129

LDB. Other Fluvents that have a cryic soil temperature

regime.

Cryofluvents, p. 128

LDC. Other Fluvents that have a xeric moisture regime.

Xerofluvents, p. 132

LDD. Other Fluvents that have an ustic moisture regime.

Ustifluvents, p. 131

LDE. Other Fluvents that have an aridic (or torric) moisture

regime.

Torrifluvents, p. 129

LDF. Other Fluvents.

Udifluvents, p. 130

Cryofluvents

Key to Subgroups

LDBA. Cryofluvents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and percent aluminum plus 1/2 the iron percentage (by

ammonium oxalate) totaling more than 1.0.

Andic Cryofluvents

LDDB. Other Cryofluvents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Cryofluvents

LDBC. Other Cryofluvents that have, in one or more horizons

within 50 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Cryofluvents

LDBD. Other Cryofluvents that are saturated with water in

one or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Cryofluvents

LDBE. Other Cryofluvents that have a color value, moist,

of 3 or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Cryofluvents

LDBF. Other Cryofluvents.

Typic Cryofluvents
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Gelifluvents

Key to Subgroups

LDAA. Gelifluvents that have, in one or more horizons within

100 cm of the mineral soil surface, both redox depletions with

chroma of 2 or less and aquic conditions for some time in

normal years (or artificial drainage).

Aquic Gelifluvents

LDAB. Other Gelifluvents.

Typic Gelifluvents

Torrifluvents

Key to Subgroups

LDEA. Torrifluvents that have:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 oC or higher; and

3. An aridic (or torric) moisture regime that borders on

ustic.

Ustertic Torrifluvents

LDEB. Other Torrifluvents that have one or both of the

following:

1. Cracks within 125 cm of the soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in most normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Vertic Torrifluvents

LDEC. Other Torrifluvents that have:

1. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 o

C or higher; and

2. A thermic, mesic, or frigid soil temperature regime and

an aridic (or torric) moisture regime that borders on xeric;

and

3. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrixerandic Torrifluvents

LDED. Other Torrifluvents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Torrifluvents

LDEE. Other Torrifluvents that have, in one or more horizons

within 100 cm of the soil surface, both redox depletions with

chroma of 2 or less and aquic conditions for some time in

normal years (or artificial drainage).

Aquic Torrifluvents

LDEF. Other Torrifluvents that are saturated with water in one

or more layers within 150 cm of the soil surface in normal years

for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Torrifluvents
130 Keys to Soil Taxonomy

LDEG. Other Torrifluvents that have:

1. A horizon within 100 cm of the mineral soil surface that

is 15 cm or more thick and that either has 20 percent or more

(by volume) durinodes or is brittle and has a firm ruptureresistance class when moist; and

2. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 oC or higher; and

3. A thermic, mesic, or frigid soil temperature regime

and an aridic (or torric) moisture regime that borders on

xeric.

Duric Xeric Torrifluvents

LDEH. Other Torrifluvents that have a horizon within 100 cm

of the mineral soil surface that is 15 cm or more thick and that

either has 20 percent or more (by volume) durinodes or is brittle

and has a firm rupture-resistance class when moist.

Duric Torrifluvents

LDEI. Other Torrifluvents that have both:

1. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 o

C or higher; and

2. An aridic (or torric) moisture regime that borders on

ustic.

Ustic Torrifluvents

LDEJ. Other Torrifluvents that have both:

1. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 o

C or higher; and

2. A thermic, mesic, or frigid soil temperature regime and

an aridic (or torric) moisture regime that borders on xeric.

Xeric Torrifluvents

LDEK. Other Torrifluvents that have an anthropic epipedon.

Anthropic Torrifluvents

LDEL. Other Torrifluvents.

Typic Torrifluvents

Udifluvents

Key to Subgroups

LDFA. Udifluvents that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. Either or both of the following:

a. In one or more horizons within 50 cm of the mineral

soil surface, redox depletions with chroma of 2 or less

and also aquic conditions for some time in normal years

(or artificial drainage); or

b. In one or more horizons within 100 cm of the mineral

soil surface, a color value, moist, of 4 or more and either

chroma of 0 or hue of 5GY, 5G, 5BG, or 5B and also

aquic conditions for some time in normal years (or

artificial drainage).

Aquertic Udifluvents

LDFB. Other Udifluvents that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Udifluvents

LDFC. Other Udifluvents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Udifluvents

LDFD. Other Udifluvents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and
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a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Udifluvents

LDFE. Other Udifluvents that have either:

1. In one or more horizons within 50 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); or

2. In one or more horizons within 100 cm of the mineral

soil surface, a color value, moist, of 4 or more and either

chroma of 0 or hue of 5GY, 5G, 5BG, or 5B and also aquic

conditions for some time in normal years (or artificial

drainage).

Aquic Udifluvents

LDFF. Other Udifluvents that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Udifluvents

LDFG. Other Udifluvents that have a color value, moist,

of 3 or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Udifluvents

LDFH. Other Udifluvents.

Typic Udifluvents

Ustifluvents

Key to Subgroups

LDDA. Ustifluvents that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. Either or both of the following:

a. In one or more horizons within 50 cm of the mineral

soil surface, redox depletions with chroma of 2 or less

and also aquic conditions for some time in normal years

(or artificial drainage); or

b. In one or more horizons within 150 cm of the mineral

soil surface, a color value, moist, of 4 or more and either

chroma of 0 or hue of 5GY, 5G, 5BG, or 5B and also

aquic conditions for some time in normal years (or

artificial drainage).

Aquertic Ustifluvents

LDDB. Other Ustifluvents that have both of the following:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that, in normal years, is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that, in normal years, is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that,

in normal years, remains moist in some or all parts for

less than 90 consecutive days per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 8 oC; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm or

a densic, lithic, or paralithic contact, whichever is

shallower.

Torrertic Ustifluvents

LDDC. Other Ustifluvents that have one or both of the

following:
132 Keys to Soil Taxonomy

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Ustifluvents

LDDD. Other Ustifluvents that have anthraquic conditions.

Anthraquic Ustifluvents

LDDE. Other Ustifluvents that have either:

1. In one or more horizons within 50 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); or

2. In one or more horizons within 150 cm of the mineral

soil surface, a color value, moist, of 4 or more and either

chroma of 0 or hue of 5GY, 5G, 5BG, or 5B and also aquic

conditions for some time in normal years (or artificial

drainage).

Aquic Ustifluvents

LDDF. Other Ustifluvents that are saturated with water in one

or more layers within 150 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Ustifluvents

LDDG. Other Ustifluvents that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid soil temperature regime and a moisture control

section that, in normal years, is dry in all parts for fourtenths or more of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that, in normal years, is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that, in

normal years, is moist in some or all parts for less than 180

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Aridic Ustifluvents

LDDH. Other Ustifluvents that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid soil temperature regime and a moisture control

section that, in normal years, is dry in some or all parts for

less than 105 cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that, in normal years, is dry in some

part for less than four-tenths of the cumulative days per year

when the temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that, in

normal years, is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Udic Ustifluvents

LDDI. Other Ustifluvents that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Ustifluvents

LDDJ. Other Ustifluvents.

Typic Ustifluvents

Xerofluvents

Key to Subgroups

LDCA. Xerofluvents that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Xerofluvents

LDCB. Other Xerofluvents that have:
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1. In one or more horizons within 50 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); or

2. In one or more horizons within 150 cm of the mineral

soil surface, a color value, moist, of 4 or more and either

chroma of 0 or hue bluer than 10Y and also aquic conditions

for some time in normal years (or artificial drainage); and

3. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Xerofluvents

LDCC. Other Xerofluvents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Xerofluvents

LDCD. Other Xerofluvents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Xerofluvents

LDCE. Other Xerofluvents that have either:

1. In one or more horizons within 50 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); or

2. In one or more horizons within 150 cm of the mineral

soil surface, a color value, moist, of 4 or more and either

chroma of 0 or hue of 5GY, 5G, 5BG, or 5B or aquic

conditions for some time in normal years.

Aquic Xerofluvents

LDCF. Other Xerofluvents that are saturated with water in

one or more layers within 150 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Xerofluvents

LDCG. Other Xerofluvents that have a horizon within 100 cm

of the mineral soil surface that is 15 cm or more thick and that

either has 20 percent or more (by volume) durinodes or is brittle

and has a firm rupture-resistance class when moist.

Durinodic Xerofluvents

LDCH. Other Xerofluvents that have a color value, moist, of

3 or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Xerofluvents

LDCI. Other Xerofluvents.

Typic Xerofluvents

Orthents

Key to Great Groups

LEA. Orthents that have, in normal years, a mean annual soil

temperature of 0 oC or colder and a mean summer soil

temperature that:

1. Is 8 oC or colder if there is no O horizon; or

2. Is 5 oC or colder if there is an O horizon.

Gelorthents, p. 134

LEB. Other Orthents that have a cryic soil temperature regime.

Cryorthents, p. 134

LEC. Other Orthents that have an aridic (or torric) moisture

regime.

Torriorthents, p. 134
134 Keys to Soil Taxonomy

LEC. Other Orthents that have a xeric moisture regime.

Xerorthents, p. 138

LED. Other Orthents that have an ustic moisture regime.

Ustorthents, p. 136

LEF. Other Orthents.

Udorthents, p. 136

Cryorthents

Key to Subgroups

LEBA. Cryorthents that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Cryorthents

LEBB. Other Cryorthents that have, throughout one

or more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Cryorthents

LEBC. Other Cryorthents that have, in one or more horizons

within 50 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Cryorthents

LEDD. Other Cryorthents that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Cryorthents

LEBE. Other Cryorthents that have lamellae within 200 cm of

the mineral soil surface.

Lamellic Cryorthents

LEBF. Other Cryorthents.

Typic Cryorthents

Gelorthents

Key to Subgroups

LEAA. Gelorthents that are saturated with water in one or

more layers within 100 cm of the mineral soil surface in normal

years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Gelorthents

LEAB. Other Gelorthents.

Typic Gelorthents

Torriorthents

Key to Subgroups

LECA. Torriorthents that have:

1. A lithic contact within 50 cm of the soil surface; and

2. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 oC or higher; and

3. A hyperthermic, thermic, mesic, frigid, or iso soil

temperature regime and an aridic (or torric) moisture regime

that borders on ustic.

Lithic Ustic Torriorthents

LECB. Other Torriorthents that have:

1. A lithic contact within 50 cm of the soil surface; and

2. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 o

C or higher; and

3. A thermic, mesic, or frigid soil temperature regime and

an aridic (or torric) moisture regime that borders on xeric.

Lithic Xeric Torriorthents

LECC. Other Torriorthents that have a lithic contact within 50

cm of the soil surface.

Lithic Torriorthents

LECD. Other Torriorthents that have:

1. One or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or
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b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower; and

2. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 oC or higher; and

3. A thermic, mesic, or frigid soil temperature regime and

an aridic (or torric) moisture regime that borders on xeric.

Xerertic Torriorthents

LECE. Other Torriorthents that have:

1. One or both of the following:

a. Cracks within 125 cm of the soil surface that are 5

mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has

its upper boundary within 125 cm of the soil surface; or

b. A linear extensibility of 6.0 cm or more between the

soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower; and

2. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 o

C or higher; and

3. An aridic (or torric) moisture regime that borders on

ustic.

Ustertic Torriorthents

LECF. Other Torriorthents that have one or both of the

following:

1. Cracks within 125 cm of the soil surface that are 5 mm

or more wide through a thickness of 30 cm or more for some

time in normal years and slickensides or wedge-shaped

aggregates in a layer 15 cm or more thick that has its upper

boundary within 125 cm of the soil surface; or

2. A linear extensibility of 6.0 cm or more between the soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Vertic Torriorthents

LECG. Other Torriorthents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Torriorthents

LECH. Other Torriorthents that have, in one or more horizons

within 100 cm of the soil surface, redox depletions with chroma

of 2 or less and also aquic conditions for some time in normal

years (or artificial drainage).

Aquic Torriorthents

LECI. Other Torriorthents that are saturated with water in one

or more layers within 150 cm of the soil surface in normal years

for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Torriorthents

LECJ. Other Torriorthents that have a horizon within 100 cm

of the soil surface that is 15 cm or more thick and that either has

20 percent or more (by volume) durinodes or is brittle and has a

firm rupture-resistance class when moist.

Duric Torriorthents

LEBC. Other Torriorthents that have both:

1. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 o

C or higher; and

2. A hyperthermic, thermic, mesic, frigid, or iso soil

temperature regime and an aridic (or torric) moisture regime

that borders on ustic.

Ustic Torriorthents

LECL. Other Torriorthents that have both:

1. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 oC or higher; and

2. A thermic, mesic, or frigid soil temperature regime

and an aridic (or torric) moisture regime that borders on

xeric.

Xeric Torriorthents
136 Keys to Soil Taxonomy

LECM. Other Torriorthents.

Typic Torriorthents

Udorthents

Key to Subgroups

LEFA. Udorthents that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Udorthents

LEFB. Other Udorthents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Udorthents

LEFC. Other Udorthents that have, in one or more horizons

within 100 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Udorthents

LEFD. Other Udorthents that are saturated with water in one

or more layers within 150 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Udorthents

LEFE. Other Udorthents that have 50 percent or more (by

volume) wormholes, wormcasts, and filled animal burrows

between either the Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and either a depth of

100 cm or a densic, lithic, paralithic, or petroferric contact,

whichever is shallower.

Vermic Udorthents

LEFF. Other Udorthents.

Typic Udorthents

Ustorthents

Key to Subgroups

LEEA. Ustorthents that have:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture

control section that, in normal years, is dry in all parts for

four-tenths or more of the cumulative days per year when

the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that, in normal years, is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that, in

normal years, remains moist in some or all parts for less

than 90 consecutive days per year when the temperature

at a depth of 50 cm below the soil surface is higher than

8 oC.

Aridic Lithic Ustorthents

LEEB. Other Ustorthents that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Ustorthents

LEEC. Other Ustorthents that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that, in normal years, is dry in all parts for four-
Entisols 137

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tenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that, in normal years, is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that, in

normal years, remains moist in some or all parts for less

than 90 consecutive days per year when the temperature

at a depth of 50 cm below the soil surface is higher than

8 oC.

Torrertic Ustorthents

LEED. Other Ustorthents that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Ustorthents

LEEE. Other Ustorthents that have anthraquic conditions.

Anthraquic Ustorthents

LEEF. Other Ustorthents that have, in one or more horizons

within 100 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Ustorthents

LEEG. Other Ustorthents that are saturated with water in one

or more layers within 150 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Ustorthents

LEEH. Other Ustorthents that have a horizon within 100

cm of the mineral soil surface that is 15 cm or more thick

and that either has 20 percent or more (by volume) durinodes or

is brittle and has a firm rupture-resistance class when moist.

Durinodic Ustorthents

LEEI. Other Ustorthents that have both:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that, in normal years, is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that, in normal years, is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that, in

normal years, remains moist in some or all parts for less

than 90 consecutive days per year when the temperature

at a depth of 50 cm below the soil surface is higher than

8 oC; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the soil surface, one or

both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitritorrandic Ustorthents

LEEJ. Other Ustorthents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Ustorthents
138 Keys to Soil Taxonomy

LEEK. Other Ustorthents that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid soil temperature regime and a moisture control

section that, in normal years, is dry in all parts for fourtenths or more of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

2. A mesic or thermic soil temperature regime and a

moisture control section that, in normal years, is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that, in

normal years, is moist in some or all parts for less than 180

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Aridic Ustorthents

LEEL. Other Ustorthents that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid soil temperature regime and a moisture control

section that, in normal years, is dry in some or all parts for

less than 105 cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that, in normal years, is dry in some

part for less than four-tenths of the cumulative days per year

when the temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that, in

normal years, is dry in some or all parts for less than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Udic Ustorthents

LEEM. Other Ustorthents that have 50 percent or more (by

volume) wormholes, wormcasts, and filled animal burrows

between either the Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and either a depth of

100 cm or a densic, lithic, paralithic, or petroferric contact,

whichever is shallower.

Vermic Ustorthents

LEEN. Other Ustorthents.

Typic Ustorthents

Xerorthents

Key to Subgroups

LEDA. Xerorthents that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Xerorthents

LEDB. Other Xerorthents that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Xerorthents

LEDC. Other Xerorthents that have, in one or more horizons

within 100 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Xerorthents

LEDD. Other Xerorthents that are saturated with water in one

or more layers within 150 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Xerorthents

LEDE. Other Xerorthents that have a horizon within 100 cm

of the mineral soil surface that is 15 cm or more thick and that

either has 20 percent or more (by volume) durinodes or is brittle

and has a firm rupture-resistance class when moist.

Durinodic Xerorthents

LEDF. Other Xerorthents that have a base saturation (by

NH4

OAc) of less than 60 percent in all horizons at a depth

between 25 and 75 cm below the mineral soil surface surface or

in the horizon directly above a root-limiting layer that is at a

shallower depth.

Dystric Xerorthents
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LEDG. Other Xerorthents.

Typic Xerorthents

Psamments

Key to Great Groups

LCA. Psamments that have a cryic soil temperature regime.

Cryopsamments, p. 139

LCB. Other Psamments that have an aridic (or torric)

moisture regime.

Torripsamments, p. 140

LCC. Other Psamments that have, in the 0.02 to 2.0 mm

fraction within the particle-size control section, a total of more

than 90 percent (by weighted average) resistant minerals.

Quartzipsamments, p. 139

LCD. Other Psamments that have an ustic moisture regime.

Ustipsamments, p. 141

LCE. Other Psamments that have a xeric moisture regime.

Xeropsamments, p. 142

LCF. Other Psamments.

Udipsamments, p. 141

Cryopsamments

Key to Subgroups

LCAA. Cryopsamments that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Cryopsamments

LCAB. Other Cryopsamments that have, in one or more

horizons within 50 cm of the mineral soil surface, redox

depletions with chroma of 2 or less and also aquic conditions

for some time in normal years (or artificial drainage).

Aquic Cryopsamments

LCAC. Other Cryopsamments that are saturated with water in

one or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Cryopsamments

LCAD. Other Cryopsamments that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction

containing 5 percent or more volcanic glass, and [(Al plus 1

/2

Fe, percent extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrandic Cryopsamments

LCAE. Other Cryopsamments that have a horizon 5 cm or

more thick that has one or more of the following:

1. In 25 percent or more of each pedon, cementation by

organic matter and aluminum, with or without iron; or

2. Al plus 1

/2 Fe percentages (by ammonium oxalate)

totaling 0.25 or more, and half that amount or less in an

overlying horizon; or

3. An ODOE value of 0.12 or more, and a value half as

high or lower in an overlying horizon.

Spodic Cryopsamments

LCAF. Other Cryopsamments that have lamellae within 200

cm of the mineral soil surface.

Lamellic Cryopsamments

LCAG. Other Cryopsamments.

Typic Cryopsamments

Quartzipsamments

Key to Subgroups

LCCA. Quartzipsamments that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Quartzipsamments

LCCB. Other Quartzipsamments that have both:

1. In one or more horizons within 100 cm of the mineral

soil surface, redox depletions with chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage); and

2. A horizon, 5 cm or more thick, either below an Ap

horizon or at a depth of 18 cm or more from the mineral soil

surface, whichever is deeper, that has one or more of the

following:

a. In 25 percent or more of each pedon, cementation

by organic matter and aluminum, with or without iron; or

b. Al plus 1

/2 Fe percentages (by ammonium oxalate)

totaling 0.25 or more, and half that amount or less in an

overlying horizon; or

c. An ODOE value of 0.12 or more, and a value half as

high or lower in an overlying horizon.

Aquodic Quartzipsamments

LCCC. Other Quartzipsamments that have, in one or

more horizons within 100 cm of the mineral soil surface,
140 Keys to Soil Taxonomy

redox depletions with chroma of 2 or less and also aquic

conditions for some time in normal years (or artificial

drainage).

Aquic Quartzipsamments

LCCD. Other Quartzipsamments that are saturated with water

in one or more layers within 100 cm of the mineral soil surface

in normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Quartzipsamments

LCCE. Other Quartzipsamments that meet all of the

following:

1. Have an ustic moisture regime; and

2. Have a clay fraction with a CEC of 16 cmol(+) or less

per kg clay (by NH4

OAc pH 7); and

3. The sum of the weighted average silt plus 2 times

the weighted average clay (both by weight) is more than 5.

Ustoxic Quartzipsamments

LCCF. Other Quartzipsamments that meet all of the

following:

1. Have a udic moisture regime; and

2. Have a clay fraction with a CEC of 16 cmol(+) or less

per kg clay (by NH4

OAc pH 7); and

3. The sum of the weighted average silt plus 2 times the

weighted average clay (both by weight) is more than 5.

Udoxic Quartzipsamments

LCCG. Other Quartzipsamments that have 5 percent or more

(by volume) plinthite in one or more horizons within 100 cm of

the mineral soil surface.

Plinthic Quartzipsamments

LCCH. Other Quartzipsamments that have both:

1. Lamellae within 200 cm of the mineral soil surface; and

2. An ustic moisture regime.

Lamellic Ustic Quartzipsamments

LCCI. Other Quartzipsamments that have lamellae within 200

cm of the mineral soil surface.

Lamellic Quartzipsamments

LCCJ. Other Quartzipsamments that have an ustic moisture

regime.

Ustic Quartzipsamments

LCCK. Other Quartzipsamments that have a xeric moisture

regime.

Xeric Quartzipsamments

LCCL. Other Quartzipsamments that have a horizon, 5 cm or

more thick, either below an Ap horizon or at a depth of 18 cm

or more from the mineral soil surface, whichever is deeper, that

has one or more of the following:

1. In 25 percent or more of each pedon, cementation by

organic matter and aluminum, with or without iron; or

2. Al plus 1

/2 Fe percentages (by ammonium oxalate)

totaling 0.25 or more, and half that amount or less in an

overlying horizon; or

3. An ODOE value of 0.12 or more, and a value half as

high or lower in an overlying horizon.

Spodic Quartzipsamments

LCCM. Other Quartzipsamments.

Typic Quartzipsamments

Torripsamments

Key to Subgroups

LCBA. Torripsamments that have a lithic contact within 50

cm of the soil surface.

Lithic Torripsamments

LCBB. Other Torripsamments that are saturated with water in

one or more layers within 150 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days

Oxyaquic Torripsamments

LCBC. Other Torripsamments that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction

containing 5 percent or more volcanic glass, and [(Al plus 1

/2

Fe, percent extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrandic Torripsamments

LCBD. Other Torripsamments that have a horizon within 100

cm of the soil surface that is 15 cm or more thick and that either

has 20 percent or more (by volume) durinodes or is brittle and

has a firm rupture-resistance class when moist.

Haploduridic Torripsamments

LCBE. Other Torripsamments that have both:
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1. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 oC or higher; and

2. An aridic (or torric) moisture regime that borders on

ustic.

Ustic Torripsamments

LCBF. Other Torripsamments that have both:

1. A moisture control section that, in normal years, is dry

in all its parts for less than three-fourths of the cumulative

days per year when the soil temperature at a depth of 50 cm

from the soil surface is 5 o

C or higher; and

2. A thermic, mesic, or frigid soil temperature regime and

an aridic (or torric) moisture regime that borders on xeric.

Xeric Torripsamments

LCBG. Other Torripsamments that have, in all horizons from

a depth of 25 to 100 cm, more than 50 percent colors that have

all of the following:

1. Hue of 2.5YR or redder; and

2. A color value, moist, of 3 or less; and

3. A dry value no more than 1 unit higher than the moist

value.

Rhodic Torripsamments

LCBH. Other Torripsamments.

Typic Torripsamments

Udipsamments

Key to Subgroups

LCFA. Udipsamments that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Udipsamments

LCFB. Other Udipsamments that have, in one or more

horizons within 100 cm of the mineral soil surface, redox

depletions with chroma of 2 or less and also aquic conditions

for some time in normal years (or artificial drainage).

Aquic Udipsamments

LCFC. Other Udipsamments that are saturated with water in

one or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Udipsamments

LCFD. Other Udipsamments that have a horizon, 5 cm or

more thick, either below an Ap horizon or at a depth of 18 cm

or more from the mineral soil surface, whichever is deeper, that

has one or more of the following:

1. In 25 percent or more of each pedon, cementation by

organic matter and aluminum, with or without iron; or

2. Al plus 1

/2 Fe percentages (by ammonium oxalate)

totaling 0.25 or more, and half that amount or less in an

overlying horizon; or

3. An ODOE value of 0.12 or more, and a value half as

high or lower in an overlying horizon.

Spodic Udipsamments

LCFE. Other Udipsamments that have lamellae within 200 cm

of the mineral soil surface.

Lamellic Udipsamments

LCFF. Other Udipsamments that have a surface horizon

between 25 and 50 cm thick that meets all of the requirements

for a plaggen epipedon except thickness.

Plagganthreptic Udipsamments

LCFG. Other Udipsamments.

Typic Udipsamments

Ustipsamments

Key to Subgroups

LCDA. Ustipsamments that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Ustipsamments

LCDB. Other Ustipsamments that have, in one or

more horizons within 100 cm of the mineral soil surface,

distinct or prominent redox concentrations and also aquic

conditions for some time in normal years (or artificial

drainage).

Aquic Ustipsamments

LCDC. Other Ustipsamments that are saturated with water in

one or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Ustipsamments

LCDD. Other Ustipsamments that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid soil temperature regime and a moisture control
142

section that, in normal years, is dry in all parts for fourtenths or more of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

2. A mesic or thermic soil temperature regime and a

moisture control section that, in normal years, is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that, in

normal years, is moist in some or all parts for less than 180

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Aridic Ustipsamments

LCDE. Other Ustipsamments that have lamellae within 200

cm of the mineral soil surface.

Lamellic Ustipsamments

LCDF. Other Ustipsamments that have, in all horizons from a

depth of 25 to 100 cm, more than 50 percent colors that have all

of the following:

1. Hue of 2.5YR or redder; and

2. A color value, moist, of 3 or less; and

3. A dry value no more than 1 unit higher than the moist

value.

Rhodic Ustipsamments

LCDG. Other Ustipsamments.

Typic Ustipsamments

Xeropsamments

Key to Subgroups

LCEA. Xeropsamments have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Xeropsamments

LCEB. Other Xeropsamments that have both:

1. In one or more horizons within 100 cm of the mineral

soil surface, distinct or prominent redox concentrations and

also aquic conditions for some time in normal years (or

artificial drainage); and

2. A horizon within 100 cm of the mineral soil surface that

is 15 cm or more thick and that either has 20 percent or more

(by volume) durinodes or is brittle and has a firm ruptureresistance class when moist.

Aquic Durinodic Xeropsamments

LCEC. Other Xeropsamments that have, in one or more

horizons within 100 cm of the mineral soil surface, distinct or

prominent redox concentrations and also aquic conditions for

some time in normal years (or artificial drainage).

Aquic Xeropsamments

LCED. Other Xeropsamments that are saturated with water in

one or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Xeropsamments

LCEE. Other Xeropsamments that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction

containing 5 percent or more volcanic glass, and [(Al plus 1

/2

Fe, percent extracted by ammonium oxalate) times 60] plus the

volcanic glass (percent) is 30 or more.

Vitrandic Xeropsamments

LCEF. Other Xeropsamments that have a horizon within

100 cm of the mineral soil surface that is 15 cm or more thick

and that either has 20 percent or more (by volume) durinodes or

is brittle and has a firm rupture-resistance class when moist.

Durinodic Xeropsamments

LCEG. Other Xeropsamments that have lamellae within 200

cm of the mineral soil surface.

Lamellic Xeropsamments

LCEH. Other Xeropsamments that have a base saturation

(by NH4

OAc) of less than 60 percent in all horizons at a depth

between 25 and 75 cm below the mineral soil surface or in the

horizon directly above a root-limiting layer that is at a

shallower depth.

Dystric Xeropsamments

LCEI. Other Xeropsamments.

Typic Xeropsamments
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Key to Suborders

AA. Gelisols that have organic soil materials that meet one or

more of the following:

1. Overlie cindery, fragmental, or pumiceous materials

and/or fill their interstices and directly below these materials

have either a densic, lithic, or paralithic contact; or

2. When added with the underlying cindery, fragmental, or

pumiceous materials, total 40 cm or more between the soil

surface and a depth of 50 cm; or

3. Are saturated with water for 30 or more cumulative days

during normal years (or are artificially drained) and have 80

percent or more, by volume, organic soil materials from the

soil surface to a depth of 50 cm or to a glacic layer or a

densic, lithic, or paralithic contact, whichever is shallowest.

Histels, p. 143

AB. Other Gelisols that have one or more horizons showing

cryoturbation in the form of irregular, broken, or distorted

horizon boundaries, involutions, the accumulation of organic

matter on top of the permafrost, ice or sand wedges, and

oriented rock fragments.

Turbels, p. 148

AC. Other Gelisols.

Orthels, p. 144

Histels

Key to Great Groups

AAA. Histels that are saturated with water for less than 30

cumulative days during normal years (and are not artificially

drained).

Folistels, p. 144

AAB. Other Histels that are saturated with water for 30 or

more cumulative days during normal years and that have both:

1. A glacic layer with its upper boundary within 100 cm of

the soil surface; and

2. Less than three-fourths (by volume) Sphagnum fibers in

the organic soil materials to a depth of 50 cm or to a densic,

lithic, or paralithic contact, whichever is shallower.

Glacistels, p. 144

AAC. Other Histels that have more thickness of fibric soil

materials than any other kind of organic soil material to a depth

of 50 cm or to a densic, lithic, or paralithic contact, whichever

is shallowest.

Fibristels, p. 143

AAD. Other Histels that have more thickness of hemic soil

materials than any other kind of organic soil material to a depth

of 50 cm or to a densic, lithic, or paralithic contact, whichever

is shallowest.

Hemistels, p. 144

AAE. Other Histels.

Sapristels, p. 144

Fibristels

Key to Subgroups

AACA. Fibristels that have a lithic contact within 100 cm of

the soil surface.

Lithic Fibristels

AACB. Other Fibristels that have a mineral layer 30 cm or

more thick within 100 cm of the soil surface.

Terric Fibristels

AACC. Other Fibristels that have, within the organic

materials, either one mineral layer 5 cm or more thick or two or

more layers of any thickness within 100 cm of the soil surface.

Fluvaquentic Fibristels

AACD. Other Fibristels in which three-fourths or more of

the fibric material is derived from Sphagnum to a depth of 50

cm or to a densic, lithic, or paralithic contact, whichever is

shallowest.

Sphagnic Fibristels

AACE. Other Fibristels.

Typic Fibristels

CHAPTER 9

Gelisols
144 Keys to Soil Taxonomy

Folistels

Key to Subgroups

AAAA. Folistels that have a lithic contact within 50 cm of the

soil surface.

Lithic Folistels

AAAB. Other Folistels that have a glacic layer with its upper

boundary within 100 cm of the soil surface.

Glacic Folistels

AAAC. Other Folistels.

Typic Folistels

Glacistels

Key to Subgroups

AABA. Glacistels that have more thickness of hemic

materials than any other kind of organic soil material in the

upper 50 cm.

Hemic Glacistels

AABB. Other Glacistels that have more thickness of sapric

materials than any other kind of organic soil material in the

upper 50 cm.

Sapric Glacistels

AABC. Other Glacistels

Typic Glacistels

Hemistels

Key to Subgroups

AADA. Hemistels that have a lithic contact within 100 cm of

the soil surface.

Lithic Hemistels

AADB. Other Hemistels that have a mineral layer 30 cm or

more thick within 100 cm of the soil surface.

Terric Hemistels

AADC. Other Hemistels that have, within the organic

materials, either one mineral layer 5 cm or more thick or two

or more layers of any thickness within 100 cm of the soil

surface.

Fluvaquentic Hemistels

AADD. Other Hemistels.

Typic Hemistels

Sapristels

Key to Subgroups

AAEA. Sapristels that have a lithic contact within 100 cm of

the soil surface.

Lithic Sapristels

AAEB. Other Sapristels that have a mineral layer 30 cm or

more thick within 100 cm of the soil surface.

Terric Sapristels

AAEC. Other Sapristels that have, within the organic

materials, either one mineral layer 5 cm or more thick or two or

more layers of any thickness within 100 cm of the soil surface.

Fluvaquentic Sapristels

AAED. Other Sapristels.

Typic Sapristels

Orthels

Key to Great Groups

ACA. Orthels that have in 30 percent or more of the pedon

more than 40 percent, by volume, organic materials from the

soil surface to a depth of 50 cm.

Historthels, p. 146

ACB. Other Orthels that have, within 50 cm of the mineral

soil surface, redox depletions with chroma of 2 or less and also

aquic conditions during normal years (or artificial drainage).

Aquorthels, p. 145

ACC. Other Orthels that have anhydrous conditions.

Anhyorthels, p. 145

ACD. Other Orthels that have a mollic epipedon.

Mollorthels, p. 147

ACE. Other Orthels that have an umbric epipedon.

Umbrorthels, p. 148

ACF. Other Orthels that have an argillic horizon that has its

upper boundary within 100 cm of the mineral soil surface.

Argiorthels, p. 146

ACG. Other Orthels that have, below the Ap horizon or below

a depth of 25 cm, whichever is deeper, less than 35 percent (by

volume) rock fragments and have a texture of loamy fine sand

or coarser in the particle-size control section.

Psammorthels, p. 147
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ACH. Other Orthels.

Haplorthels, p. 146

Anhyorthels

Key to Subgroups

ACCA. Anhyorthels that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Anhyorthels

ACCB. Other Anhyorthels that have a glacic layer that has its

upper boundary within 100 cm of the mineral soil surface.

Glacic Anhyorthels

ACCC. Other Anhyorthels that have a petrogypsic horizon

that has its upper boundary within 100 cm of the mineral soil

surface.

Petrogypsic Anhyorthels

ACCD. Other Anhyorthels that have a gypsic horizon that has

its upper boundary within 100 cm of the mineral soil surface.

Gypsic Anhyorthels

ACCE. Other Anhyorthels that have a horizon 15 cm or more

thick that contains 12 cmol(-)/L in 1:5 soil:water nitrate and in

which the product of its thickness (in cm) and its nitrate

concentration is 3,500 or more.

Nitric Anhyorthels

ACCF. Other Anhyorthels that have a salic horizon that has its

upper boundary within 100 cm of the mineral soil surface.

Salic Anhyorthels

ACCG. Other Anhyorthels that have a calcic horizon with its

upper boundary within 100 cm of the mineral soil surface.

Calcic Anhyorthels

ACCH. Other Anhyorthels.

Typic Anhyorthels

Aquorthels

Key to Subgroups

ACBA. Aquorthels that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Aquorthels

ACBB. Other Aquorthels that have a glacic layer that has its

upper boundary within 100 cm of the mineral soil surface.

Glacic Aquorthels

ACBC. Other Aquorthels that have a sulfuric horizon or

sulfidic materials with an upper boundary within 100 cm of the

mineral soil surface.

Sulfuric Aquorthels

ACBD. Other Aquorthels that have either:

1. Organic soil materials that are discontinuous at the

surface; or

2. Organic soil materials at the surface that change in

thickness fourfold or more within a pedon.

Ruptic-Histic Aquorthels

ACBE. Other Aquorthels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Aquorthels

ACBF. Other Aquorthels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Aquorthels

ACBG. Other Aquorthels that have a salic horizon that

has its upper boundary within 100 cm of the mineral soil

surface.

Salic Aquorthels

ACBH. Other Aquorthels that have less than 35 percent (by

volume) rock fragments and a texture of loamy fine sand or

coarser in all layers within the particle-size control section.

Psammentic Aquorthels

ACBI. Other Aquorthels that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or
146 Keys to Soil Taxonomy

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm or a densic, lithic, or paralithic contact, whichever

is shallower.

Fluvaquentic Aquorthels

ACBJ. Other Aquorthels.

Typic Aquorthels

Argiorthels

Key to Subgroups

ACFA. Argiorthels that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Argiorthels

ACFB. Other Argiorthels that have a glacic layer that has its

upper boundary within 100 cm of the mineral soil surface.

Glacic Argiorthels

ACFC. Other Argiorthels that have a natric horizon.

Natric Argiorthels

ACFD. Other Argiorthels.

Typic Argiorthels

Haplorthels

Key to Subgroups

ACHA. Haplorthels that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haplorthels

ACHB. Other Haplorthels that have a glacic layer that has its

upper boundary within 100 cm of the mineral soil surface.

Glacic Haplorthels

ACHC. Other Haplorthels that have a slope of less than 25

percent; and

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artifical

drainage); and

2. Either:

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a

depth of 125 cm or a densic, lithic, or paralithic contact,

whichever is shallower.

Fluvaquentic Haplorthels

ACHD. Other Haplorthels that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time

during normal years (or artificial drainage).

Aquic Haplorthels

ACHE. Other Haplorthels that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm or a densic, lithic, or paralithic contact, whichever

is shallower.

Fluventic Haplorthels

ACHF. Other Haplorthels.

Typic Haplorthels

Historthels

Key to Subgroups

ACAA. Historthels that have a lithic contact within 50 cm of

the soil surface.

Lithic Historthels

ACAB. Other Historthels that have a glacic layer that has its

upper boundary within 100 cm of the soil surface.

Glacic Historthels

ACAC. Other Historthels that have a slope of less than 25

percent; and

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artifical

drainage); and

 2. Either:

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a
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depth of 125 cm or a densic, lithic or paralithic contact,

which ever is shallower.

Fluvaquentic Historthels

ACAD. Other Historthels that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm or a densic, lithic or paralithic contact, which ever

is shallower.

 Fluventic Historthels

ACAE. Other Historthels that have more than 40 percent, by

volume, organic soil materials from the soil surface to a depth

of 50 cm in 75 percent or less of the pedon.

Ruptic Historthels

ACAF. Other Historthels.

Typic Historthels

Mollorthels

Key to Subgroups

ACDA. Mollorthels that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Mollorthels

ACDB. Other Mollorthels that have a glacic layer that has its

upper boundary within 100 cm of the mineral soil surface.

Glacic Mollorthels

ACDC. Other Mollorthels that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time during normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallowest.

Vertic Mollorthels

ACDD. Other Mollorthels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Mollorthels

ACDE. Other Mollorthels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Mollorthels

ACDF. Other Mollorthels that have:

1. A mollic epipedon 40 cm or more thick with a texture

finer than loamy fine sand; and

2. A slope of less than 25 percent.

Cumulic Mollorthels

ACDG. Other Mollorthels that have, in one or more horizons

within 100 cm of the mineral soil surface, distinct or prominent

redox concentrations and also aquic conditions for some time

during normal years (or artificial drainage).

Aquic Mollorthels

ACDH. Other Mollorthels.

Typic Mollorthels

Psammorthels

Key to Subgroups

ACGA. Psammorthels that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Psammorthels

ACGB. Other Psammorthels that have a glacic layer that

has its upper boundary within 100 cm of the mineral soil

surface.

Glacic Psammorthels

ACGC. Other Psammorthels that have a horizon 5 cm or more

thick that has one or more of the following:
148 Keys to Soil Taxonomy

1. In 25 percent or more of each pedon, cementation by

organic matter and aluminum, with or without iron; or

2. Al plus 1/2 Fe percentages (by ammonium oxalate)

totaling 0.25 or more, and half that amount or less in an

overlying horizon; or

3. An ODOE value of 0.12 or more, and a value half as

high or lower in an overlying horizon.

Spodic Psammorthels

ACGD. Other Psammorthels.

Typic Psammorthels

Umbrorthels

Key to Subgroups

ACEA. Umbrorthels that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Umbrorthels

ACEB. Other Umbrorthels that have a glacic layer that has its

upper boundary within 100 cm of the mineral soil surface.

Glacic Umbrorthels

ACEC. Other Umbrorthels that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time during normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallowest.

Vertic Umbrorthels

ACED. Other Umbrorthels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Umbrorthels

ACEE. Other Umbrorthels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Umbrorthels

ACEF. Other Umbrorthels that have:

1. An umbric epipedon 40 cm or more thick with a texture

finer than loamy fine sand; and

2. A slope of less than 25 percent.

Cumulic Umbrorthels

ACEG. Other Umbrorthels that have, in one or more horizons

within 100 cm of the mineral soil surface, distinct or prominent

redox concentrations and also aquic conditions for some time

during normal years (or artificial drainage).

Aquic Umbrorthels

ACEH. Other Umbrorthels.

Typic Umbrorthels

Turbels

Key to Great Groups

ABA. Turbels that have in 30 percent or more of the pedon

more than 40 percent, by volume, organic materials from the

soil surface to a depth of 50 cm.

Histoturbels, p. 149

ABB. Other Turbels that have, within 50 cm of the mineral

soil surface, redox depletions with chroma of 2 or less and also

aquic conditions during normal years (or artificial drainage).

Aquiturbels, p. 149

ABC. Other Turbels that have anhydrous conditions.

Anhyturbels, p. 149

ABD. Other Turbels that have a mollic epipedon.

Molliturbels, p. 150

ABE. Other Turbels that have an umbric epipedon.

Umbriturbels, p. 150

ABF. Other Turbels that have less than 35 percent (by

volume) rock fragments and a texture of loamy fine sand or

coarser in all layers within the particle-size control section.

Psammoturbels, p. 150
Gelisols 149

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ABG. Other Turbels.

Haploturbels, p. 149

Anhyturbels

Key to Subgroups

ABCA. Anhyturbels that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Anhyturbels

ABCB. Other Anhyturbels that have a glacic layer with its

upper boundary within 100 cm of the mineral soil surface.

Glacic Anhyturbels

ABCC. Other Anhyturbels that have a petrogypsic horizon

with its upper boundary within 100 cm of the mineral soil

surface.

Petrogypsic Anhyturbels

ABCD. Other Anhyturbels that have a gypsic horizon

with its upper boundary within 100 cm of the mineral soil

surface.

Gypsic Anhyturbels

ABCE. Other Anhyturbels that have a horizon 15 cm or more

thick that contains 12 cmol(-)/L nitrate in 1:5 soil:water extract

and in which the product of its thickness (in cm) and its nitrate

concentration is 3,500 or more.

Nitric Anhyturbels

ABCF. Other Anhyturbels that have a salic horizon

that has its upper boundary within 100 cm of the mineral soil

surface.

Salic Anhyturbels

ABCG. Other Anhyturbels that have a calcic horizon

that has its upper boundary within 100 cm of the mineral soil

surface.

Calcic Anhyturbels

ABCH. Other Anhyturbels.

Typic Anhyturbels

Aquiturbels

Key to Subgroups

ABBA. Aquiturbels that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Aquiturbels

ABBB. Other Aquiturbels that have a glacic layer with its

upper boundary within 100 cm of the mineral soil surface.

Glacic Aquiturbels

ABBC. Other Aquiturbels that have a sulfuric horizon or

sulfidic materials with an upper boundary within 100 cm of the

mineral soil surface.

Sulfuric Aquiturbels

ABBD. Other Aquiturbels that have either:

1. Organic soil materials that are discontinous at the

surface; or

2. Organic soil materials at the surface that change in

thickness fourfold or more within a pedon.

Ruptic-Histic Aquiturbels

ABBE. Other Aquiturbels that have less than 35 percent (by

volume) rock fragments and a texture of loamy fine sand or

coarser in all layers within the particle-size control section.

Psammentic Aquiturbels

ABBF. Other Aquiturbels.

Typic Aquiturbels

Haploturbels

Key to Subgroups

ABGA. Haploturbels that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Haploturbels

ABGB. Other Haploturbels that have a glacic layer that has an

upper boundary within 100 cm of the mineral soil surface.

Glacic Haploturbels

ABGC. Other Haploturbels that have, in one or more horizons

within 100 cm of the mineral soil surface, distinct or prominent

redox concentrations and also aquic conditions for some time

during normal years (or artificial drainage).

Aquic Haploturbels

ABGD. Other Haploturbels.

Typic Haploturbels

Histoturbels

Key to Subgroups

ABAA. Histoturbels that have a lithic contact within 50 cm of

the soil surface.

Lithic Histoturbels

ABAB. Other Histoturbels that have a glacic layer with its

upper boundary within 100 cm of the soil surface.

Glacic Histoturbels

ABAC. Other Histoturbels that have more than 40 percent, by
150 Keys to Soil Taxonomy

volume, organic soil materials from the soil surface to a depth

of 50 cm in 75 percent or less of the pedon.

Ruptic Histoturbels

ABAD. Other Histoturbels.

Typic Histoturbels

Molliturbels

Key to Subgroups

ABDA. Molliturbels that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Molliturbels

ABDB. Other Molliturbels that have a glacic layer that has its

upper boundary within 100 cm of the mineral soil surface.

Glacic Molliturbels

ABDC. Other Molliturbels that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time during normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallowest.

Vertic Molliturbels

ABDD. Other Molliturbels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Molliturbels

ABDE. Other Molliturbels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Molliturbels

ABDF. Other Molliturbels that have:

1. A mollic epipedon 40 cm or more thick with a texture

finer than loamy fine sand; and

2. A slope of less than 25 percent.

Cumulic Molliturbels

ABDG. Other Molliturbels that have, in one or more horizons

within 100 cm of the mineral soil surface, distinct or prominent

redox concentrations and also aquic conditions for some time

during normal years (or artificial drainage).

Aquic Molliturbels

ABDH. Other Molliturbels.

Typic Molliturbels

Psammoturbels

Key to Subgroups

ABFA. Psammoturbels that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Psammoturbels

ABFB. Other Psammoturbels that have a glacic layer that has

its upper boundary within 100 cm of the mineral soil surface.

Glacic Psammoturbels

ABFC. Other Psammoturbels that have a horizon 5 cm or

more thick that has one or more of the following:

1. In 25 percent or more of each pedon, cementation

by organic matter and aluminum, with or without iron;

or

2. Al plus 1

/2 Fe percentages (by ammonium oxalate)

totaling 0.25 or more, and half that amount or less in an

overlying horizon; or

3. An ODOE value of 0.12 or more, and a value half as

high or lower in an overlying horizon.

Spodic Psammoturbels

ABFD. Other Psammoturbels.

Typic Psammoturbels

Umbriturbels

Key to Subgroups

ABEA. Umbriturbels that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Umbriturbels
Gelisols 151

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ABEB. Other Umbriturbels that have a glacic layer that has its

upper boundary within 100 cm of the mineral soil surface.

Glacic Umbriturbels

ABEC. Other Umbriturbels that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time during normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm or

a densic, lithic, or paralithic contact, whichever is shallowest.

Vertic Umbriturbels

ABED. Other Umbriturbels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Umbriturbels

ABEE. Other Umbriturbels that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Umbriturbels

ABEF. Other Umbriturbels that have:

1. An umbric epipedon 40 cm or more thick with a texture

finer than loamy fine sand; and

2. A slope of less than 25 percent.

Cumulic Umbriturbels

ABEG. Other Umbriturbels that have, in one or more

horizons within 100 cm of the mineral soil surface, distinct or

prominent redox concentrations and also aquic conditions for

some time during normal years (or artificial drainage).

Aquic Umbriturbels

ABEH. Other Umbriturbels.

Typic Umbriturbels

153

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Key to Suborders

BA. Histosols that are saturated with water for less than 30

cumulative days during normal years (and are not artificially

drained).

Folists, p. 154

BB. Other Histosols that:

1. Have more thickness of fibric soil materials than any

other kind of organic soil material either:

a. In the organic parts of the subsurface tier if there is

no continuous mineral layer 40 cm or more thick that has

its upper boundary within the subsurface tier; or

b. In the combined thickness of the organic parts

of the surface and subsurface tiers if there is a continuous

mineral layer 40 cm or more thick that has its upper

boundary within the subsurface tier; and

2. Do not have a sulfuric horizon that has its upper

boundary within 50 cm of the soil surface; and

3. Do not have sulfidic materials within 100 cm of the

soil surface.

Fibrists, p. 153

BC. Other Histosols that have more thickness of sapric soil

materials than any other kind of organic soil materials either:

1. In the organic parts of the subsurface tier if there is no

continuous mineral layer 40 cm or more thick that has its

upper boundary within the subsurface tier; or

2. In the combined thickness of the organic parts of the

surface and subsurface tiers if there is a continuous mineral

layer 40 cm or more thick that has its upper boundary within

the subsurface tier.

Saprists, p. 156

BD. Other Histosols.

Hemists, p. 155

Fibrists

Key to Great Groups

BBA. Fibrists that have a cryic soil temperature regime.

Cryofibrists, p. 153

BBB. Other Fibrists in which fibric Sphagnum constitutes

three-fourths or more of the volume to either a depth of 90 cm

from the soil surface or to a densic, lithic, or paralithic contact,

fragmental materials, or other mineral soil materials if at a

depth of less than 90 cm.

Sphagnofibrists, p. 154

BBC. Other Fibrists.

Haplofibrists, p. 154

Cryofibrists

Key to Subgroups

BBAA. Cryofibrists that have a layer of water within the

control section, below the surface tier.

Hydric Cryofibrists

BBAB. Other Cryofibrists that have a lithic contact within the

control section.

Lithic Cryofibrists

BBAC. Other Cryofibrists that have a mineral layer 30 cm or

more thick that has its upper boundary within the control

section, below the surface tier.

Terric Cryofibrists

BBAD. Other Cryofibrists that have, within the organic

materials, either one mineral layer 5 cm or more thick or two or

more mineral layers of any thickness in the control section,

below the surface tier.

Fluvaquentic Cryofibrists

CHAPTER 10

Histosols
154 Keys to Soil Taxonomy

BBAE. Other Cryofibrists in which three-fourths or more of

the fiber volume in the surface tier is derived from Sphagnum.

Sphagnic Cryofibrists

BBAF. Other Cryofibrists.

Typic Cryofibrists

Haplofibrists

Key to Subgroups

BBCA. Haplofibrists that have a layer of water within the

control section, below the surface tier.

Hydric Haplofibrists

BBCB. Other Haplofibrists that have a lithic contact within

the control section.

Lithic Haplofibrists

BBCC. Other Haplofibrists that have one or more limnic layers

with a total thickness of 5 cm or more within the control section.

Limnic Haplofibrists

BBCD. Other Haplofibrists that have a mineral layer 30 cm or

more thick that has its upper boundary within the control

section, below the surface tier.

Terric Haplofibrists

BBCE. Other Haplofibrists that have, within the organic

materials, either one mineral layer 5 cm or more thick or two or

more mineral layers of any thickness in the control section,

below the surface tier.

Fluvaquentic Haplofibrists

BBCF. Other Haplofibrists that have one or more layers of

hemic and sapric materials with a total thickness of 25 cm or

more in the control section, below the surface tier.

Hemic Haplofibrists

BBCG. Other Haplofibrists.

Typic Haplofibrists

Sphagnofibrists

Key to Subgroups

BBBA. Sphagnofibrists that have a layer of water within the

control section, below the surface tier.

Hydric Sphagnofibrists

BBBB. Other Sphagnofibrists that have a lithic contact within

the control section.

Lithic Sphagnofibrists

BBBC. Other Sphagnofibrists that have one or more limnic

layers with a total thickness of 5 cm or more within the control

section.

Limnic Sphagnofibrists

BBBD. Other Sphagnofibrists that have a mineral layer 30 cm

or more thick that has its upper boundary within the control

section, below the surface tier.

Terric Sphagnofibrists

BBBE. Other Sphagnofibrists that have, within the organic

materials, either one mineral layer 5 cm or more thick or two or

more mineral layers of any thickness in the control section,

below the surface tier.

Fluvaquentic Sphagnofibrists

BBBF. Other Sphagnofibrists that have one or more layers of

hemic and sapric materials with a total thickness of 25 cm or

more in the control section, below the surface tier.

Hemic Sphagnofibrists

BBBG. Other Sphagnofibrists.

Typic Sphagnofibrists

Folists

Key to Great Groups

BAA. Folists that have a cryic soil temperature regime.

Cryofolists, p. 154

BAB. Other Folists that have an aridic (or torric) soil moisture

regime.

Torrifolists, p. 155

BAC. Other Folists that have an ustic or xeric soil moisture

regime.

Ustifolists, p. 155

BAD. Other Folists.

Udifolists, p. 155

Cryofolists

Key to Subgroups

BAAA. Cryofolists that have a lithic contact within 50 cm of

the soil surface.

Lithic Cryofolists

BAAB. Other Cryofolists.

Typic Cryofolists
Histosols 155

H

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Torrifolists

Key to Subgroups

BABA. Torrifolists that have a lithic contact within 50 cm of

the soil surface.

Lithic Torrifolists

BABB. Other Torrifolists.

Typic Torrifolists

Udifolists

Key to Subgroups

BADA. Udifolists that have a lithic contact within 50 cm of

the soil surface.

Lithic Udifolists

BADB. Other Udifolists.

Typic Udifolists

Ustifolists

Key to Subgroups

BACA. Ustifolists that have a lithic contact within 50 cm of

the soil surface.

Lithic Ustifolists

BACB. Other Ustifolists.

Typic Ustifolists

Hemists

Key to Great Groups

BDA. Hemists that have a sulfuric horizon that has its upper

boundary within 50 cm of the soil surface.

Sulfohemists, p. 156

BDB. Other Hemists that have sulfidic materials within 100

cm of the soil surface.

Sulfihemists, p. 156

BDC. Other Hemists that have a horizon 2 cm or more thick

in which humilluvic materials constitute one-half or more of the

volume.

Luvihemists, p. 156

BDD. Other Hemists that have a cryic temperature

regime.

Cryohemists, p. 155

BDE. Other Hemists.

Haplohemists, p. 155

Cryohemists

Key to Subgroups

BDDA. Cryohemists that have a layer of water within the

control section, below the surface tier.

Hydric Cryohemists

BDDB. Other Cryohemists that have a lithic contact within

the control section.

Lithic Cryohemists

BDDC. Other Cryohemists that have a mineral layer 30 cm or

more thick that has its upper boundary within the control

section, below the surface tier.

Terric Cryohemists

BDDD. Other Cryohemists that have, within the organic

materials, either one mineral layer 5 cm or more thick or two or

more mineral layers of any thickness in the control section,

below the surface tier.

Fluvaquentic Cryohemists

BDDE. Other Cryohemists.

Typic Cryohemists

Haplohemists

Key to Subgroups

BDEA. Haplohemists that have a layer of water within the

control section, below the surface tier.

Hydric Haplohemists

BDEB. Other Haplohemists that have a lithic contact within

the control section.

Lithic Haplohemists

BDEC. Other Haplohemists that have one or more limnic

layers with a total thickness of 5 cm or more within the control

section.

Limnic Haplohemists

BDED. Other Haplohemists that have a mineral layer 30 cm

or more thick that has its upper boundary within the control

section, below the surface tier.

Terric Haplohemists

BDEE. Other Haplohemists that have, within the organic
156 Keys to Soil Taxonomy

materials, either one mineral layer 5 cm or more thick or two or

more mineral layers of any thickness in the control section,

below the surface tier.

Fluvaquentic Haplohemists

BDEF. Other Haplohemists that have one or more layers of

fibric materials with a total thickness of 25 cm or more in the

control section, below the surface tier.

Fibric Haplohemists

BDEG. Other Haplohemists that have one or more layers of

sapric materials with a total thickness of 25 cm or more below

the surface tier.

Sapric Haplohemists

BDEH. Other Haplohemists.

Typic Haplohemists

Luvihemists

Key to Subgroups

BDCA. All Luvihemists (provisionally).

Typic Luvihemists

Sulfihemists

Key to Subgroups

BDBA. Sulfihemists that have a mineral layer 30 cm or more

thick that has its upper boundary within the control section,

below the surface tier.

Terric Sulfihemists

BDBB. Other Sulfihemists.

Typic Sulfihemists

Sulfohemists

Key to Subgroups

BDAA. All Sulfohemists (provisionally).

Typic Sulfohemists

Saprists

Key to Great Groups

BCA. Saprists that have a sulfuric horizon that has its upper

boundary within 50 cm of the soil surface.

Sulfosaprists, p. 157

BCB. Other Saprists that have sulfidic materials within 100

cm of the soil surface.

Sulfisaprists, p. 157

BCC. Other Saprists that have a cryic temperature regime.

Cryosaprists, p. 156

BCD. Other Saprists.

Haplosaprists, p. 156

Cryosaprists

Key to Subgroups

BCCA. Cryosaprists that have a lithic contact within the

control section.

Lithic Cryosaprists

BCCB. Other Cryosaprists that have one or more limnic

layers with a total thickness of 5 cm or more within the control

section.

Limnic Cryosaprists

BCCC. Other Cryosaprists that have a mineral layer 30 cm or

more thick that has its upper boundary within the control

section, below the surface tier.

Terric Cryosaprists

BCCD. Other Cryosaprists that have, within the organic

materials, either one mineral layer 5 cm or more thick or two or

more mineral layers of any thickness in the control section,

below the surface tier.

Fluvaquentic Cryosaprists

BCCE. Other Cryosaprists.

Typic Cryosaprists

Haplosaprists

Key to Subgroups

BCDA. Haplosaprists that have a lithic contact within the

control section.

Lithic Haplosaprists

BCDB. Other Haplosaprists that have one or more limnic layers

with a total thickness of 5 cm or more within the controlsection.

Limnic Haplosaprists

BCDC. Other Haplosaprists that have both:

1. Throughout a layer 30 cm or thick that has its upper

boundary within the control section, an electrical

conductivity of 30 dS/m or more (1:1 soil:water) for 6

months or more during normal years; and

2. A mineral layer 30 cm or more thick that has its

upper boundary within the control section, below the surface

tier.

Halic Terric Haplosaprists
Histosols 157

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BCDD. Other Haplosaprists that have throughout a layer 30

cm or more thick within the control section, an electrical

conductivity of 30 dS/m or more (1:1 soil:water) for 6 months

or more during normal years.

Halic Haplosaprists

BCDE. Other Haplosaprists that have a mineral layer 30 cm

or more thick that has its upper boundary within the control

section, below the surface tier.

Terric Haplosaprists

BCDF. Other Haplosaprists that have, within the organic

materials, either one mineral layer 5 cm or more thick or two or

more mineral layers of any thickness in the control section,

below the surface tier.

Fluvaquentic Haplosaprists

BCDG. Other Haplosaprists that have one or more layers of

fibric or hemic materials with a total thickness of 25 cm or

more in the control section, below the surface tier.

Hemic Haplosaprists

BCDH. Other Haplosaprists.

Typic Haplosaprists

Sulfisaprists

Key to Subgroups

BCBA. Sulfisaprists that have a mineral layer 30 cm or more

thick that has its upper boundary within the control section,

below the surface tier.

Terric Sulfisaprists

BCBB. Other Sulfisaprists.

Typic Sulfisaprists

Sulfosaprists

Key to Subgroups

BCAA. All Sulfosaprists (provisionally).

Typic Sulfosaprists

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Key to Suborders

KA. Inceptisols that have one or more of the following:

1. In a layer above a densic, lithic, or paralithic contact or

in a layer at a depth between 40 and 50 cm from the mineral

soil surface, whichever is shallower, aquic conditions for

some time in normal years (or artificial drainage) and one or

more of the following:

a. A histic epipedon; or

b. A sulfuric horizon that has its upper boundary within

50 cm of the mineral soil surface; or

c. A layer directly under the epipedon, or within 50 cm

of the mineral soil surface, that has, on faces of peds or in

the matrix if peds are absent, 50 percent or more chroma

of either:

(1) 2 or less if there are redox concentrations; or

(2) 1 or less; or

d. Within 50 cm of the mineral soil surface, enough

active ferrous iron to give a positive reaction to

alpha,alpha-dipyridyl at a time when the soil is not being

irrigated; or

2. An exchangeable sodium percentage (ESP) of 15 or

more (or a sodium adsorption ratio [SAR] of 13 or more) in

half or more of the soil volume within 50 cm of the mineral

soil surface, a decrease in ESP (or SAR) values with

increasing depth below 50 cm, and ground water within 100

cm of the mineral soil surface for some time during the year.

Aquepts, p. 159

KB. Other Inceptisols that have a plaggen or anthropic

epipedon.

Anthrepts, p. 159

KC. Other Inceptisols that have, in normal years, a mean

annual soil temperature of 0 o

C or colder and a mean summer

soil temperature that:

1. Is 8 oC or colder if there is no O horizon; or

2. Is 5 oC or colder if there is an O horizon.

Gelepts, p. 171

KD. Other Inceptisols that have a cryic soil temperature

regime.

Cryepts, p. 166

KE. Other Inceptisols that have an ustic soil moisture regime.

Ustepts, p. 177

KF. Other Inceptisols that have a xeric soil moisture regime.

Xerepts, p. 184

KG. Other Inceptisols.

Udepts, p. 172

Anthrepts

Key to Great Groups

KBA. Anthrepts that have a plaggen epipedon.

Plagganthrepts, p. 159

KBB. Other Anthrepts.

Haplanthrepts, p. 159

Haplanthrepts

Key to Subgroups

KBBA. All Haplanthrepts (provisionally).

Typic Haplanthrepts

Plagganthrepts

Key to Subgroups

KBAA. All Plagganthrepts (provisionally).

Typic Plagganthrepts

Aquepts

Key to Great Groups

KAA. Aquepts that have a sulfuric horizon that has its upper

boundary within 50 cm of the mineral soil surface.

Sulfaquepts, p. 165

CHAPTER 11

Inceptisols
160 Keys to Soil Taxonomy

KAB. Other Aquepts that have, within 100 cm of the mineral

soil surface, one or more horizons in which plinthite or a

cemented or indurated diagnostic horizon either forms a

continuous phase or constitutes one-half or more of the volume.

Petraquepts, p. 165

KAC. Other Aquepts that have either:

1. A salic horizon; or

2. In one or more horizons with a total thickness of 25 cm

or more within 50 cm of the mineral soil surface, an

exchangeable sodium percentage (ESP) of 15 or more (or

a sodium adsorption ratio [SAR] of 13 or more) and a

decrease in ESP (or SAR) values with increasing depth

below 50 cm.

Halaquepts, p. 164

KAD. Other Aquepts that have a fragipan with its upper

boundary within 100 cm of the mineral soil surface.

Fragiaquepts, p. 163

KAE. Other Aquepts that have, in normal years, a mean

annual soil temperature of 0 o

C or colder and a mean summer

soil temperature that:

1. Is 8 oC or colder if there is no O horizon; or

2. Is 5 oC or colder if there is an O horizon.

Gelaquepts, p. 163

KAF. Other Aquepts that have a cryic soil temperature

regime.

Cryaquepts, p. 160

KAG. Other Aquepts that have, in one or more layers at least

25 cm thick (cumulative) within 100 cm of the mineral soil

surface, 25 percent or more (by volume) recognizable

bioturbation, such as filled animal burrows, wormholes, or casts.

Vermaquepts, p. 165

KAH. Other Aquepts that have a histic, melanic, mollic, or

umbric epipedon.

Humaquepts, p. 164

KAI. Other Aquepts that have episaturation.

Epiaquepts, p. 162

KAJ. Other Aquepts.

Endoaquepts, p. 161

Cryaquepts

Key to Subgroups

KAFA. Cryaquepts that have, within 150 cm of the mineral

soil surface, one or more of the following:

1. A sulfuric horizon; or

2. A horizon 15 cm or more thick that has all of the

characteristics of a sulfuric horizon, except that it has a pH

between 3.5 and 4.0; or

3. Sulfidic materials.

Sulfic Cryaquepts

KAFB. Other Cryaquepts that have both a histic epipedon and

a lithic contact within 50 cm of the mineral soil surface.

Histic Lithic Cryaquepts

KAFC. Other Cryaquepts that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Cryaquepts

KAFD. Other Cryaquepts that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Cryaquepts

KAFE. Other Cryaquepts that have a histic epipedon.

Histic Cryaquepts

KAFF. Other Cryaquepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Cryaquepts
Inceptisols 161

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KAFG. Other Cryaquepts that have a slope of less than 25

percent; and

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluvaquentic Cryaquepts

KAFH. Other Cryaquepts that have both:

1. Chroma of 3 or more in 40 percent or more of the matrix

of one or more horizons at a depth between 15 and 50 cm

from the mineral soil surface; and

2. A mollic or umbric epipedon.

Aeric Humic Cryaquepts

KAFI. Other Cryaquepts that have chroma of 3 or more in 40

percent or more of the matrix of one or more horizons at a

depth between 15 and 50 cm from the mineral soil surface.

Aeric Cryaquepts

KAFJ. Other Cryaquepts that have a mollic or umbric

epipedon.

Humic Cryaquepts

KAFK. Other Cryaquepts.

Typic Cryaquepts

Endoaquepts

Key to Subgroups

KAJA. Endoaquepts that have, within 150 cm of the mineral

soil surface, one or more of the following:

1. A sulfuric horizon; or

2. A horizon 15 cm or more thick that has all of the

characteristics of a sulfuric horizon, except that it has a pH

between 3.5 and 4.0; or

3. Sulfidic materials.

Sulfic Endoaquepts

KAJB. Other Endoaquepts that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Endoaquepts

KAJC. Other Endoaquepts that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Endoaquepts

KAJD. Other Endoaquepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Endoaquepts

KAJE. Other Endoaquepts that have, in one or more horizons

between the A or Ap horizon and a depth of 75 cm below the

mineral soil surface, one of the following colors:

1. Hue of 7.5YR or redder in 50 percent or more of the

matrix; and

a. If peds are present, either chroma of 2 or more on 50

percent or more of ped exteriors or no redox depletions

with chroma of 2 or less in ped interiors; or

b. If peds are absent, a chroma of 2 or more in 50

percent or more of the matrix; or

2. In 50 percent or more of the matrix, hue of 10YR or

yellower; and either

a. Both a color value, moist, and chroma of 3 or more;

or

b. Chroma of 2 or more if there are no redox

concentrations; and

3. A slope of less than 25 percent; and

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent
162 Keys to Soil Taxonomy

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a

depth of 125 cm below the mineral soil surface or a

densic, lithic, or paralithic contact, whichever is

shallower.

Fluventic Endoaquepts

KAJF. Other Endoaquepts that have a slope of less than 25

percent; and

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluvaquentic Endoaquepts

KAJG. Other Endoaquepts that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Endoaquepts

KAJH. Other Endoaquepts that have, in one or more horizons

between the A or Ap horizon and a depth of 75 cm below the

mineral soil surface, one of the following colors:

1. Hue of 7.5YR or redder in 50 percent or more of the

matrix; and

a. If peds are present, either chroma of 2 or more on 50

percent or more of ped exteriors or no redox depletions

with chroma of 2 or less in ped interiors; or

b. If peds are absent, chroma of 2 or more in 50 percent

or more of the matrix; or

2. In 50 percent or more of the matrix, hue of 10YR or

yellower and either:

a. Both a color value, moist, and chroma of 3 or more;

or

b. Chroma of 2 or more if there are no redox

concentrations.

Aeric Endoaquepts

KAJI. Other Endoaquepts that have:

1. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 15 cm of the mineral soil, or materials between the

mineral soil surface and a depth of 15 cm have these color

values after mixing; and

2. A base saturation (by NH4

OAc) of less than 50 percent

in some part within 100 cm of the mineral soil surface.

Humic Endoaquepts

KAJJ. Other Endoaquepts that have a color value, moist,

of 3 or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Endoaquepts

KAJK. Other Endoaquepts.

Typic Endoaquepts

Epiaquepts

Key to Subgroups

KAIA. Epiaquepts that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Epiaquepts

KAIB. Other Epiaquepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium
Inceptisols 163

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oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Epiaquepts

KAIC. Other Epiaquepts that have a slope of less than 25

percent; and

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluvaquentic Epiaquepts

KAID. Other Epiaquepts that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Epiaquepts

KAIE. Other Epiaquepts that have, in one or more horizons

between the A or Ap horizon and a depth of 75 cm below the

mineral soil surface, one of the following colors:

1. Hue of 7.5YR or redder in 50 percent or more of the

matrix; and

a. If peds are present, either chroma of 2 or more on 50

percent or more of ped exteriors or no redox depletions

with chroma of 2 or less in ped interiors; or

b. If peds are absent, chroma of 2 or more in 50 percent

or more of the matrix; or

2. In 50 percent or more of the matrix, hue of 10YR or

yellower and either:

a. Both a color value, moist, and chroma of 3 or more;

or

b. Chroma of 2 or more if there are no redox

concentrations.

Aeric Epiaquepts

KAIF. Other Epiaquepts that have both:

1. A color value, moist, of 3 or less and a color value, dry,

of 5 or less (crushed and smoothed sample) throughout the

upper 15 cm of the mineral soil, or materials between the

mineral soil surface and a depth of 15 cm have these color

values after mixing; and

2. A base saturation (by NH4

OAc) of less than

50 percent in some part within 100 cm of the mineral

soil surface.

Humic Epiaquepts

KAIG. Other Epiaquepts that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) throughout the upper 15 cm of the mineral

soil or have materials between the mineral soil surface and a

depth of 15 cm that have these color values after mixing.

Mollic Epiaquepts

KAIH. Other Epiaquepts.

Typic Epiaquepts

Fragiaquepts

Key to Subgroups

KADA. Fragiaquepts that have, in 50 percent or more of the

matrix of one or more horizons either between the plow layer and

a depth of 75 cm below the mineral soil surface or, if there is no

plow layer, between depths of 15 and 75 cm, chroma of either:

1. 3 or more; or

2. 2 or more if there are no redox concentrations.

Aeric Fragiaquepts

KADB. Other Fragiaquepts that have a histic, mollic, or

umbric epipedon.

Humic Fragiaquepts

KADC. Other Fragiaquepts.

Typic Fragiaquepts

Gelaquepts

Key to Subgroups

KAEA. Gelaquepts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Gelaquepts

KAEB. Other Gelaquepts that have a histic epipedon.

Histic Gelaquepts

KAEC. Other Gelaquepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or
164 Keys to Soil Taxonomy

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Gelaquepts

KAED. Other Gelaquepts that have a slope of less than 25

percent; and

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluvaquentic Gelaquepts

KAEE. Other Gelaquepts that have a mollic or umbric

epipedon.

Humic Gelaquepts

KAEF. Other Gelaquepts.

Typic Gelaquepts

Halaquepts

Key to Subgroups

KACA. Halaquepts that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Halaquepts

KACB. Other Halaquepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Halaquepts

KACC. Other Halaquepts that have a horizon 15 cm or more

thick that has 20 percent or more (by volume) cemented or

indurated soil material and has its upper boundary within 100

cm either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Duric Halaquepts

KACD. Other Halaquepts that have chroma of 3 or more in 40

percent or more of the matrix of one or more horizons at a

depth between 15 and 75 cm from the mineral soil surface.

Aeric Halaquepts

KACE. Other Halaquepts.

Typic Halaquepts

Humaquepts

Key to Subgroups

KAHA. Humaquepts that have an n value of either:

1. More than 0.7 (and less than 8 percent clay) in one or

more layers at a depth between 20 and 50 cm from the

mineral soil surface; or

2. More than 0.9 in one or more layers at a depth

between 50 and 100 cm.

Hydraquentic Humaquepts

KAHB. Other Humaquepts that have a histic epipedon.

Histic Humaquepts

KAHC. Other Humaquepts that have, throughout one or more
Inceptisols 165

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horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Humaquepts

KAHD. Other Humaquepts that have a slope of less than 25

percent; and

1. An umbric or mollic epipedon 60 cm or more thick; and

either

2. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

3. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Cumulic Humaquepts

KAHE. Other Humaquepts that have a slope of less than 25

percent; and

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluvaquentic Humaquepts

KAHF. Other Humaquepts that have hue of 5Y or redder and

chroma of 3 or more in more than 40 percent of the matrix of

one or more subhorizons at a depth between 15 and 75 cm from

the mineral soil surface.

Aeric Humaquepts

KAHG. Other Humaquepts.

Typic Humaquepts

Petraquepts

Key to Subgroups

KABA. Petraquepts that have both:

1. A histic epipedon; and

2. A placic horizon.

Histic Placic Petraquepts

KABB. Other Petraquepts that have a placic horizon.

Placic Petraquepts

KABC. Other Petraquepts that have one or more horizons

within 125 cm of the mineral soil surface in which plinthite

either forms a continuous phase or constitutes one-half or more

of the volume.

Plinthic Petraquepts

KABD. Other Petraquepts.

Typic Petraquepts

Sulfaquepts

Key to Subgroups

KAAA. Sulfaquepts that have a salic horizon within 75 cm of

the mineral soil surface.

Salidic Sulfaquepts

KAAB. Other Sulfaquepts that have an n value of either:

1. More than 0.7 (and 8 or more percent clay) in one or

more layers at a depth between 20 and 50 cm from the

mineral soil surface; or

2. More than 0.9 in one or more layers at a depth between

50 and 100 cm from the mineral soil surface.

Hydraquentic Sulfaquepts

KAAC. Other Sulfaquepts.

Typic Sulfaquepts

Vermaquepts

Key to Subgroups

KAGA. Vermaquepts that have an exchangeable sodium

percentage of 7 or more (or a sodium adsorption ratio [SAR] of

6 or more) in one or more subhorizons within 100 cm of the

mineral soil surface.

Sodic Vermaquepts
166 Keys to Soil Taxonomy

KAGB. Other Vermaquepts.

Typic Vermaquepts

Cryepts

Key to Great Groups

KDA. Cryepts that have an umbric or mollic epipedon.

Humicryepts, p. 169

KDB. Other Cryepts that have a calcic or petrocalcic horizon

that has its upper boundary within 100 cm of the mineral soil

surface.

Calcicryepts, p. 166

KDC. Other Cryepts that:

1. Do not have free carbonates within 200 cm of the

mineral soil surface; and

2. Have base saturation (by NH4

OAc) of less than 50

percent, either:

a. In one-half or more of the thickness between 25 and

75 cm below the mineral soil surface and do not have a

placic horizon, duripan, fragipan, or densic, lithic, or

paralithic contact within 50 cm of the mineral soil

surface; or

b. In a layer, 10 cm or more thick, directly above a

placic horizon, duripan, fragipan, or densic, lithic, or

paralithic contact within 50 cm of the mineral soil

surface.

Dystrocryepts, p. 166

KDD. Other Cryepts.

Haplocryepts, p. 168

Calcicryepts

Key to Subgroups

KDBA. Calcicryepts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Calcicryepts

KDBB. Other Calcicryepts that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Calcicryepts

KDBC. Other Calcicryepts that have a xeric moisture regime.

Xeric Calcicryepts

KDBD. Other Calcicryepts that are dry in some part of the

moisture control section for 45 or more days (cumulative) in

normal years.

Ustic Calcicryepts

KDBE. Other Calcicryepts.

Typic Calcicryepts

Dystrocryepts

Key to Subgroups

KDCA. Dystrocryepts that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Dystrocryepts

KDCB. Other Dystrocryepts that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1⁄2 Fe (by ammonium oxalate) of 1.0 percent or more;

or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1⁄2 Fe, percent extracted by ammonium

oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Dystrocryepts

KDCC. Other Dystrocryepts that have both:

1. A xeric moisture regime; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface, a

fine-earth fraction with both a bulk density of 1.0 g/cm3 or

less, measured at 33 kPa water retention, and Al plus 1⁄2 Fe

(by ammonium oxalate) of 1.0 percent or more.

Haploxerandic Dystrocryepts
Inceptisols 167

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KDCD. Other Dystrocryepts that have both:

1. A xeric moisture regime; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1⁄2 Fe, percent extracted by ammonium

oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrixerandic Dystrocryepts

KDCE. Other Dystrocryepts that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction with both

a bulk density of 1.0 g/cm3

 or less, measured at 33 kPa water

retention, and Al plus 1⁄2 Fe (by ammonium oxalate) of 1.0

percent or more.

Andic Dystrocryepts

KDCF. Other Dystrocryepts that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1⁄2 Fe, percent extracted by ammonium

oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Dystrocryepts

KDCG. Other Dystrocryepts that have both:

1. A slope of less than 25 percent; and either

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a

depth of 125 cm or a densic, lithic, or paralithic contact,

whichever is shallower; and

2. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Fluvaquentic Dystrocryepts

KDCH. Other Dystrocryepts that have, in one or more

horizons within 75 cm of the mineral soil surface, redox

depletions with chroma of 2 or less and also aquic conditions

for some time in normal years (or artificial drainage).

Aquic Dystrocryepts

KDCI. Other Dystrocryepts that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Dystrocryepts

KDCJ. Other Dystrocryepts that have lamellae (two or more)

within 200 cm of the mineral soil surface.

Lamellic Dystrocryepts

KDCK. Other Dystrocryepts that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or more

and no densic, lithic, or paralithic contact within that depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm or a densic, lithic, or paralithic contact, whichever

is shallower.

Fluventic Dystrocryepts

KDCL. Other Dystrocryepts that have a horizon 5 cm or more

thick that has one or more of the following:

1. In 25 percent or more of each pedon, cementation by

organic matter and aluminum, with or without iron; or

2. Al plus 1⁄2 Fe (by ammonium oxalate) of 0.25 percent or

more and half that amount or less in an overlying horizon; or

3. An ODOE value of 0.12 or more and a value half as

high or lower in an overlying horizon.

Spodic Dystrocryepts

KDCM. Other Dystrocryepts that have a xeric moisture regime.

Xeric Dystrocryepts
168 Keys to Soil Taxonomy

KDCN. Other Dystrocryepts that are dry in some part of the

moisture control section for 45 or more days (cumulative) in

normal years.

Ustic Dystrocryepts

KDCO. Other Dystrocryepts that have base saturation (by

NH4OAc) of 50 percent or more in one or more horizons

between 25 and 50 cm from the mineral soil surface.

Eutric Dystrocryepts

KDCP. Other Dystrocryepts.

Typic Dystrocryepts

Haplocryepts

Key to Subgroups

KDDA. Haplocryepts that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Haplocryepts

KDDB. Other Haplocryepts that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1⁄2 Fe (by ammonium oxalate) of 1.0 percent or more;

or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1⁄2 Fe, percent extracted by ammonium

oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Haplocryepts

KDDC. Other Haplocryepts that have both:

1. A xeric moisture regime; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface, a

fine-earth fraction with both a bulk density of 1.0 g/cm3

 or

less, measured at 33 kPa water retention, and Al plus 1⁄2 Fe

(by ammonium oxalate) of 1.0 percent or more.

Haploxerandic Haplocryepts

KDDD. Other Haplocryepts that have both:

1. A xeric moisture regime; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1⁄2 Fe, percent extracted by ammonium

oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrixerandic Haplocryepts

KDDE. Other Haplocryepts that have both:

1. A moisture control section that is dry in some part for 45

or more days (cumulative) in normal years; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface, a

fine-earth fraction with both a bulk density of 1.0 g/cm3

 or

less, measured at 33 kPa water retention, and Al plus 1⁄2 Fe

(by ammonium oxalate) of 1.0 percent or more.

Haplustandic Haplocryepts

KDDF. Other Haplocryepts that have both:

1. A moisture control section that is dry in some part for 45

or more days (cumulative) in normal years; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1⁄2 Fe, percent extracted by ammonium
Inceptisols 169

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oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Ustivitrandic Haplocryepts

KDDG. Other Haplocryepts that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction with both

a bulk density of 1.0 g/cm3 or less, measured at 33 kPa water

retention, and Al plus 1⁄2 Fe (by ammonium oxalate) of 1.0

percent or more.

Andic Haplocryepts

KDDH. Other Haplocryepts that have, throughout one

or more horizons with a total thickness of 18 cm or more

within 75 cm of the mineral soil surface, one or both of the

following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1⁄2 Fe, percent extracted by ammonium

oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Haplocryepts

KDDI. Other Haplocryepts that have both:

1. A slope of less than 25 percent; and either

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a

depth of 125 cm or a densic, lithic, or paralithic contact,

whichever is shallower; and

2. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Fluvaquentic Haplocryepts

KDDJ. Other Haplocryepts that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Haplocryepts

KDDK. Other Haplocryepts that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplocryepts

KDDL. Other Haplocryepts that have lamellae (two or more)

within 200 cm of the mineral soil surface.

Lamellic Haplocryepts

KDDM. Other Haplocryepts that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or more

and no densic, lithic, or paralithic contact within that depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm or a densic, lithic, or paralithic contact, whichever

is shallower.

Fluventic Haplocryepts

KDDN. Other Haplocryepts that have identifiable secondary

carbonates within 100 cm of the mineral soil surface.

Calcic Haplocryepts

KDDO. Other Haplocryepts that have a xeric moisture regime.

Xeric Haplocryepts

KDDP. Other Haplocryepts that are dry in some part of the

moisture control section for 45 or more days (cumulative) in

normal years.

Ustic Haplocryepts

KDDQ. Other Haplocryepts.

Typic Haplocryepts

Humicryepts

Key to Subgroups

KDAA. Humicryepts that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Humicryepts

KDAB. Other Humicryepts that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Throughout one or more horizons with a total thickness
170 Keys to Soil Taxonomy

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1⁄2 Fe (by ammonium oxalate) of 1.0 percent or more;

or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1⁄2 Fe, percent extracted by ammonium

oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Humicryepts

KDAC. Other Humicryepts that have both:

1. A xeric moisture regime; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface, a

fine-earth fraction with both a bulk density of 1.0 g/cm3 or

less, measured at 33 kPa water retention, and Al plus 1⁄2 Fe

(by ammonium oxalate) of 1.0 percent or more.

Haploxerandic Humicryepts

KDAD. Other Humicryepts that have both:

1. A xeric moisture regime; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1⁄2 Fe, percent extracted by ammonium

oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrixerandic Humicryepts

KDAE. Other Humicryepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1⁄2 Fe (by ammonium oxalate) of 1.0 percent or

more.

Andic Humicryepts

KDAF. Other Humicryepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1⁄2 Fe, percent extracted by ammonium

oxalate) times (60)] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Humicryepts

KDAG. Other Humicryepts that have both:

1. A slope of less than 25 percent; and either

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a

depth of 125 cm or a densic, lithic, or paralithic contact,

whichever is shallower; and

2. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Fluvaquentic Humicryepts

KDAH. Other Humicryepts that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Humicryepts

KDAI. Other Humicryepts that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Humicryepts
Inceptisols 171

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KDAJ. Other Humicryepts that have lamellae (two or more)

within 200 cm of the mineral soil surface.

Lamellic Humicryepts

KDAK. Other Humicryepts that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm or a densic, lithic, or paralithic contact, whichever

is shallower.

Fluventic Humicryepts

KDAL. Other Humicryepts that have a horizon 5 cm or more

thick that has one or more of the following:

1. In 25 percent or more of each pedon, cementation by

organic matter and aluminum, with or without iron; or

2. Al plus 1⁄2 Fe (by ammonium oxalate) of 0.25 percent or

more and half that amount or less in an overlying horizon; or

3. An ODOE value of 0.12 or more and a value half as

high or lower in an overlying horizon.

Spodic Humicryepts

KDAM. Other Humicryepts that have a xeric moisture

regime.

Xeric Humicryepts

KDAN. Other Humicryepts that have base saturation (by

NH4

OAc) of 50 percent or more in one-half or more of the soil

thickness between 25 and 75 cm from the mineral soil surface

or in some part of the 10 cm directly above a densic, lithic, or

paralithic contact less than 50 cm below the mineral soil

surface.

Eutric Humicryepts

KDAO. Other Humicryepts.

Typic Humicryepts

Gelepts

Key to Great Groups

KCA. Gelepts that have one or both of the following:

1. Free carbonates within the soils; or

2. A base saturation (by NH4OAc) of 60 percent or more

in one or more horizons at a depth between 25 and 75 cm

from the mineral soil surface or directly above a rootlimiting layer if at a shallower depth.

Eutrogelepts, p. 171

KCB. Other Gelepts.

Dystrogelepts, p. 171

Dystrogelepts

Key to Subgroups

KCBA. Dystrogelepts that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Dystrogelepts

KCBB. Other Dystrogelepts that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction with both

a bulk density of 1.0 g/cm3

 or less, measured at 33 kPa water

retention, and Al plus 1/2 Fe percentages (by ammonium

oxalate) totaling more than 1.0.

Andic Dystrogelepts

 KCBC. Other Dystrogelepts that have, in one or more

horizons within 75 cm of the mineral soil surface, redox

depletions with chroma of 2 or less and also aquic conditions

for some time in normal years (or artificial drainage).

Aquic Dystrogelepts

KCBD. Other Dystrogelepts that have a mollic or umbric

epipedon.

Humic Dystrogelepts

KCBE. Other Dystrogelepts.

Typic Dystrogelepts

Eutrogelepts

Key to Subgroups

KCAA. Eutrogelepts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Eutrogelepts

KCAB. Other Eutrogelepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Eutrogelepts

KCAC. Other Eutrogelepts that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with
172 Keys to Soil Taxonomy

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Eutrogelepts

KCAD. Other Eutrogelepts that have a mollic or umbric

epipedon.

Humic Eutrogelepts

KCAE. Other Eutrogelepts.

Typic Eutrogelepts

Udepts

Key to Great Groups

KGA. Udepts that have a sulfuric horizon within 50 cm of the

mineral soil surface.

Sulfudepts, p. 177

KGB. Other Udepts that have a duripan or another cemented

or indurated soil layer that has its upper boundary within 100

cm of the mineral soil surface.

Durudepts, p. 172

KGC. Other Udepts that have a fragipan with its upper

boundary within 100 cm of the mineral soil surface.

Fragiudepts, p. 177

KGD. Other Udepts that have one or both of the following:

1. Free carbonates within the soils; or

2. A base saturation (by NH4

OAc) of 60 percent or more in

one or more horizons at a depth between 25 and 75 cm from

the mineral soil surface or directly above a root-limiting

layer if at a shallower depth.

Eutrudepts, p. 175

KGE. Other Udepts.

Dystrudepts, p. 173

Durudepts

Key to Subgroups

KGBA. Durudepts that have both:

1. In one or more horizons above the duripan and within

60 cm of the mineral soil surface, distinct or prominent

redox concentrations and also aquic conditions for some

time in normal years (or artificial drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more, above the duripan and within 75 cm of the

mineral soil surface, one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Durudepts

KGBB. Other Durudepts that have, throughout one or more

horizons with a total thickness of 18 cm or more, above the

duripan and within 75 cm of the mineral soil surface, a fineearth fraction with both a bulk density of 1.0 g/cm3

 or less,

measured at 33 kPa water retention, and Al plus 1/2 Fe

percentages (by ammonium oxalate) totaling more than 1.0.

Andic Durudepts

KGBC. Other Durudepts that have, throughout one or more

horizons with a total thickness of 18 cm or more, above the

duripan and within 75 cm of the mineral soil surface, one or

both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Durudepts

KGBD. Other Durudepts that have, in one or more horizons

above the duripan and within 30 cm of the mineral soil surface,

distinct or prominent redox concentrations and also aquic

conditions for some time in normal years (or artificial drainage).

Aquic Durudepts

KGBE. Other Durudepts.

Typic Durudepts
Inceptisols 173

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Dystrudepts

Key to Subgroups

KGEA. Dystrudepts that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. An umbric or mollic epipedon.

Humic Lithic Dystrudepts

KGEB. Other Dystrudepts that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Dystrudepts

KGEC. Other Dystrudepts that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Dystrudepts

KGED. Other Dystrudepts that have both:

1. In one or more horizons within 60 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Dystrudepts

KGEE. Other Dystrudepts that have both:

1. In one or more horizons with a total thickness of 18 cm

or more within 75 cm of the mineral soil surface, a fine-earth

with both a bulk density of 1.0 g/cm3

 or less, measured at

33 kPa water retention, and Al plus 1/2 Fe percentages (by

ammonium oxalate) totaling more than 1.0; and

2. Saturation with water within 100 cm of the mineral soil

surface in normal years for either or both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Andic Oxyaquic Dystrudepts

KGEF. Other Dystrudepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Dystrudepts

KGEG. Other Dystrudepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Dystrudepts

KGEH. Other Dystrudepts that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and
174 Keys to Soil Taxonomy

2. In one or more horizons within 60 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions in normal years (or artificial drainage).

Fragiaquic Dystrudepts

KGEI. Other Dystrudepts that have a slope of less than 25

percent; and

1. In one or more horizons within 60 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Either:

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a

depth of 125 cm below the mineral soil surface or a

densic, lithic, or paralithic contact, whichever is

shallower.

Fluvaquentic Dystrudepts

KGEJ. Other Dystrudepts that have both:

1. An umbric or mollic epipedon; and

2. In one or more horizons within 60 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Aquic Humic Dystrudepts

KGEK. Other Dystrudepts that have, in one or more horizons

within 60 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Dystrudepts

KGEL. Other Dystrudepts that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Dystrudepts

KGEM. Other Dystrudepts that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Dystrudepts

KGEN. Other Dystrudepts that have lamellae (two or more)

within 200 cm of the mineral soil surface.

Lamellic Dystrudepts

KGEO. Other Dystrudepts that have both:

1. An umbric or mollic epipedon; and

2. A sandy particle-size class throughout the particle-size

control section.

Humic Psammentic Dystrudepts

KGEP. Other Dystrudepts that have a slope of less than 25

percent; and

1. An umbric or mollic epipedon; and

2. Either:

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a

depth of 125 cm below the mineral soil surface or a

densic, lithic, or paralithic contact, whichever is

shallower.

Fluventic Humic Dystrudepts

KGEQ. Other Dystrudepts that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluventic Dystrudepts

KGER. Other Dystrudepts that have a horizon 5 cm or more

thick that has one or more of the following:

1. In 25 percent or more of each pedon, cementation by

organic matter and aluminum, with or without iron; or

2. Al plus 1

/2 Fe percentages (by ammonium oxalate)

totaling 0.25 or more, and half that amount or less in an

overlying horizon; or
Inceptisols 175

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3. An ODOE value of 0.12 or more, and a value half as

high or lower in an overlying horizon.

Spodic Dystrudepts

KGES. Other Dystrudepts that have in 50 percent or more of

the soil volume between a depth of 25 cm from the mineral soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact if shallower:

1. A CEC (by 1N NH4

OAc pH 7) of less than 24 cmol(+)

per kg clay; or

2. Both a ratio of measured clay in the fine-earth fraction

to percent water retained at 1500 kPa tension of 0.6 or more

and the following: the CEC (by 1N NH4OAc pH 7) divided

by the product of three times [percent water retained at 1500

kPa tension minus percent organic carbon (but no more than

1.00)] is less than 24.

Oxic Dystrudepts

KGET. Other Dystrudepts that have an umbric or mollic

epipedon that is 50 cm or more thick.

Humic Pachic Dystrudepts

KGEU. Other Dystrudepts that have an umbric or mollic

epipedon.

Humic Dystrudepts

KGEV. Other Dystrudepts that have both:

1. In each pedon a cambic horizon that includes 10 to 50

percent (by volume) illuvial parts that otherwise meet the

requirements for an argillic, kandic, or natric horizon; and

2. A base saturation (by sum of cations) of 35 percent or

more either at a depth of 125 cm from the top of the cambic

horizon or directly above a densic, lithic, or paralithic

contact if shallower.

Ruptic-Alfic Dystrudepts

KGEW. Other Dystrudepts that have in each pedon a cambic

horizon that includes 10 to 50 percent (by volume) illuvial parts

that otherwise meet the requirements for an argillic, kandic, or

natric horizon.

Ruptic-Ultic Dystrudepts

KGEX. Other Dystrudepts.

Typic Dystrudepts

Eutrudepts

Key to Subgroups

KGDA. Eutrudepts that have both:

1. An umbric or mollic epipedon; and

2. A lithic contact within 50 cm of the mineral soil surface.

Humic Lithic Eutrudepts

KGDB. Other Eutrudepts that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Eutrudepts

KGDC. Other Eutrudepts that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. In one or more horizons within 60 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Aquertic Eutrudepts

KGDD. Other Eutrudepts that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Eutrudepts

KGDE. Other Eutrudepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Eutrudepts

KGDF. Other Eutrudepts that have, throughout one or

more horizons with a total thickness of 18 cm or more

within 75 cm of the mineral soil surface, one or both of the

following:

1. More than 35 percent (by volume) fragments coarser
176 Keys to Soil Taxonomy

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Eutrudepts

KGDG. Other Eutrudepts that have anthraquic conditions.

Anthraquic Eutrudepts

KGDH. Other Eutrudepts that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. In one or more horizons within 60 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions in normal years (or artificial drainage).

Fragiaquic Eutrudepts

KGDI. Other Eutrudepts that have a slope of less than 25

percent; and

1. In one or more horizons within 60 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Either:

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either

a depth of 125 cm below the mineral soil surface or

a densic, lithic, or paralithic contact, whichever is

shallower.

Fluvaquentic Eutrudepts

KGDJ. Other Eutrudepts that:

1. Have, in one or more horizons within 60 cm of the

mineral soil surface, redox depletions with chroma of 2 or

less and also aquic conditions for some time in normal years

(or artificial drainage); and

2. Do not have free carbonates throughout any horizon

within 100 cm of the mineral soil surface.

Aquic Dystric Eutrudepts

KGDK. Other Eutrudepts that have, in one or more horizons

within 60 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Eutrudepts

KGDL. Other Eutrudepts that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Eutrudepts

KGDM. Other Eutrudepts that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Eutrudepts

KGDN. Other Eutrudepts that have lamellae (two or more)

within 200 cm of the mineral soil surface.

Lamellic Eutrudepts

KGDO. Other Eutrudepts that have a slope of less than 25

percent; and

1. Do not have free carbonates throughout any

horizon within 100 cm of the mineral soil surface; and either

2. Have, at a depth of 125 cm below the mineral soil

surface, an organic-carbon content (Holocene age) of 0.2

percent or more and no densic, lithic, or paralithic contact

within that depth; or

3. Have an irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Dystric Fluventic Eutrudepts

KGDP. Other Eutrudepts that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or
Inceptisols 177

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more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene Age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluventic Eutrudepts

KGDQ. Other Eutrudepts that have a sandy or sandy-skeletal

particle-size class in all horizons within 50 cm of the mineral

soil surface.

Arenic Eutrudepts

KGDR. Other Eutrudepts that do not have free carbonates

throughout any horizon within 100 cm of the mineral soil

surface.

Dystric Eutrudepts

KGDS. Other Eutrudepts that have 40 percent or more free

carbonates, including coarse fragments as much as 75 mm in

diameter, in all horizons between the top of the cambic horizon

and either a depth of 100 cm from the mineral soil surface or a

densic, lithic, or paralithic contact if shallower.

Rendollic Eutrudepts

KGDT. Other Eutrudepts that have an umbric or mollic

epipedon.

Humic Eutrudepts

KGDU. Other Eutrudepts that have a cambic horizon that

includes 10 to 50 percent (by volume) illuvial parts that

otherwise meet the requirements for an argillic, kandic, or natric

horizon.

Ruptic-Alfic Eutrudepts

KGDV. Other Eutrudepts.

Typic Eutrudepts

Fragiudepts

Key to Subgroups

KGCA. Fragiudepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Fragiudepts

KGCB. Other Fragiudepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Fragiudepts

KGCC. Other Fragiudepts that have, in one or more horizons

within 30 cm of the mineral soil surface, distinct or prominent

redox concentrations and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Fragiudepts

KGCD. Other Fragiudepts that have an umbric or mollic

epipedon.

Humic Fragiudepts

KGCE. Other Fragiudepts.

Typic Fragiudepts

Sulfudepts

Key to Subgroups

KGAA. All Sulfudepts (provisionally).

Typic Sulfudepts

Ustepts

Key to Great Groups

KEA. Ustepts that have a duripan that has its upper boundary

within 100 cm of the mineral soil surface.

Durustepts, p. 179

KEB. Other Ustepts that both:

1. Have a calcic horizon with its upper boundary

within 100 cm of the mineral soil surface or a petrocalcic

horizon that has its upper boundary within 150 cm of the

mineral soil surface; and

2. Are either calcareous or have a texture of loamy fine

sand or coarser in all parts above the calcic or petrocalcic

horizon, after the soil between the mineral soil surface and a

depth of 18 cm has been mixed.

Calciustepts, p. 178
178 Keys to Soil Taxonomy

KEC. Other Ustepts that have both of the following:

1. No free carbonates within 200 cm of the mineral soil

surface; and

2. A base saturation (by NH4OAc) of less than 60 percent

in all horizons at a depth between 25 and 75 cm from the

mineral soil surface.

Dystrustepts, p. 179

KED. Other Ustepts.

Haplustepts, p. 180

Calciustepts

Key to Subgroups

KEBA. Calciustepts that have a petrocalcic horizon and a

lithic contact within 50 cm of the mineral soil surface.

Lithic Petrocalcic Calciustepts

KEBB. Other Calciustepts that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Calciustepts

KEBC. Other Calciustepts that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some or all parts for six-tenths or more of the cumulative

days per year when the temperature at a depth of 50 cm

below the soil surface is higher than 5 o

C; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 o

C; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the temperature

at a depth of 50 cm below the soil surface is higher

than 5 oC.

Torrertic Calciustepts

KEBD. Other Calciustepts that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Calciustepts

KEBE. Other Calciustepts that have a petrocalcic horizon that

has its upper boundary within 100 cm of the mineral soil

surface.

Petrocalcic Calciustepts

KEBF. Other Calciustepts that have a gypsic horizon that has

its upper boundary within 100 cm of the mineral soil surface.

Gypsic Calciustepts

KEBG. Other Calciustepts that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Calciustepts

KEBH. Other Calciustepts that have, when neither irrigated

nor fallowed to store moisture, one of the following:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the cumulative days per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

or all parts for six-tenths or more of the cumulative days per

year when the temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

3. A hyperthermic, isomesic, or warmer iso soil
Inceptisols 179

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temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the temperature

at a depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Calciustepts

KEBI. Other Calciustepts that have, when neither irrigated

nor fallowed to store moisture, either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

or all parts for four-tenths or less of the consecutive days per

year when the temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that

in normal years is dry in some or all parts for fewer

than 120 cumulative days per year when the temperature

at a depth of 50 cm below the soil surface is higher than

8 oC.

Udic Calciustepts

KEBJ. Other Calciustepts.

Typic Calciustepts

Durustepts

Key to Subgroups

KEAA. All Durustepts (provisionally).

Typic Durustepts

Dystrustepts

Key to Subgroups

KECA. Dystrustepts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Dystrustepts

KECB. Other Dystrustepts that have both:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid soil temperature regime and a moisture

control section that in normal years is dry in all parts for

four-tenths or more of the cumulative days per year when

the temperature at a depth of 50 cm below the soil surface

is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that, in 6 normal years, is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

5 oC; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Torrertic Dystrustepts

KECC. Other Dystrustepts that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Dystrustepts

KECD. Other Dystrustepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk
180 Keys to Soil Taxonomy

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Dystrustepts

KECE. Other Dystrustepts that have, throughout one

or more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Dystrustepts

KECF. Other Dystrustepts that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Dystrustepts

KECG. Other Dystrustepts that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluventic Dystrustepts

KECH. Other Dystrustepts that, when neither irrigated nor

fallowed to store moisture, have one of the following;:

1. A frigid soil temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the cumulative days per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

or all parts for six-tenths or more of the cumulative days per

year when the soil temperature at a depth of 50 cm below the

soil surface is higher than 5 o

C; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 o

C;

and

b. Is dry in some part for six-tenths or more of the

cumulative days per year when the temperature at a depth

of 50 cm below the soil surface is higher than 5 oC.

Aridic Dystrustepts

KECI. Other Dystrustepts that have in 50 percent or more of

the soil volume between a depth of 25 cm from the mineral soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact if shallower:

1. A CEC (by 1N NH4

OAc pH 7) of less than 24 cmol(+)

per kg clay; or

2. Both a ratio of measured clay in the fine-earth fraction

to percent water retained at 1500 kPa tension of 0.6 or more

and the following: the CEC (by 1N NH4OAc pH 7) divided

by the product of three times [percent water retained at 1500

kPa tension minus percent organic carbon (but no more than

1.00)] is less than 24.

Oxic Dystrustepts

KECJ. Other Dystrustepts that have an umbric or mollic

epipedon.

Humic Dystrustepts

KECK. Other Dystrustepts.

Typic Dystrustepts

Haplustepts

Key to Subgroups

KEDA. Haplustepts that have:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. When neither irrigated nor fallowed to store moisture,

either:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days
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per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Lithic Haplustepts

KEDB. Other Haplustepts that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Haplustepts

KEDC. Other Haplustepts that have both:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid soil temperature regime and a moisture

control section that in normal years is dry in some or all

parts for fewer than 105 cumulative days per year when

the temperature at a depth of 50 cm below the soil surface

is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for less than four-tenths of the cumulative days

per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the temperature at a depth

of 50 cm below the soil surface is higher than 8 oC; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Udertic Haplustepts

KEDD. Other Haplustepts that have both:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid soil temperature regime and a moisture

control section that in normal years is dry in all parts for

four-tenths or more of the cumulative days per year when

the temperature at a depth of 50 cm below the soil surface

is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

5 oC; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Torrertic Haplustepts

KEDE. Other Haplustepts that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Haplustepts
182 Keys to Soil Taxonomy

KEDF. Other Haplustepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haplustepts

KEDG. Other Haplustepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Haplustepts

KEDH. Other Haplustepts that have anthraquic conditions.

Anthraquic Haplustepts

KEDI. Other Haplustepts that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Haplustepts

KEDJ. Other Haplustepts that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplustepts

KEDK. Other Haplustepts that have in 50 percent or more of

the soil volume between a depth of 25 cm from the mineral soil

surface and either a depth of 100 cm or a densic, lithic, or

paralithic contact if shallower:

1. A CEC (by 1N NH4

OAc pH 7) of less than 24 cmol(+)

per kg clay; or

2. Both a ratio of measured clay in the fine-earth fraction

to percent water retained at 1500 kPa tension of 0.6 or more

and the following: the CEC (by 1N NH4OAc pH 7) divided

by the product of three times [percent water retained at 1500

kPa tension minus percent organic carbon (but no more than

1.00)] is less than 24.

Oxic Haplustepts

KEDL. Other Haplustepts that have lamellae (two or more)

within 200 cm of the mineral soil surface.

Lamellic Haplustepts

KEDM. Other Haplustepts that have a slope of less than 25

percent; and

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid soil temperature regime and a moisture

control section that in normal years is dry in all parts for

four-tenths or more of the cumulative days per year when

the temperature at a depth of 50 cm below the soil surface

is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

5 oC; and

2. Either:

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either

a depth of 125 cm below the mineral soil surface or

a densic, lithic, or paralithic contact, whichever is

shallower.

Torrifluventic Haplustepts

KEDN. Other Haplustepts that have a slope of less than 25

percent; and

1. When neither irrigated nor fallowed to store moisture,

one of the following:
Inceptisols 183

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a. A frigid soil temperature regime and a moisture

control section that in normal years is dry in some or all

parts for fewer than 105 cumulative days per year when

the temperature at a depth of 50 cm below the soil surface

is higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for less than four-tenths of the cumulative days

per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the temperature at a depth

of 50 cm below the soil surface is higher than 8 oC; and

2. Either:

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a

depth of 125 cm below the mineral soil surface or a

densic, lithic, or paralithic contact, whichever is

shallower.

Udifluventic Haplustepts

KEDO. Other Haplustepts that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluventic Haplustepts

KEDP. Other Haplustepts that have a gypsic horizon that

has its upper boundary within 100 cm of the mineral soil

surface.

Gypsic Haplustepts

KEDQ. Other Haplustepts that have both:

1. A calcic horizon that has its upper boundary within 100

cm of the mineral soil surface; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid soil temperature regime and a moisture

control section that in normal years is dry in all parts for

four-tenths or more of the cumulative days per year when

the temperature at a depth of 50 cm below the soil surface

is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

5 oC.

Haplocalcidic Haplustepts

KEDR. Other Haplustepts that have both:

1. A calcic horizon that has its upper boundary within 100

cm of the mineral soil surface; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid soil temperature regime and a moisture

control section that in normal years is dry in some or all

parts for fewer than 105 cumulative days per year when

the temperature at a depth of 50 cm below the soil surface

is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for less than four-tenths of the cumulative days

per year when the temperature at a depth of 50 cm below

the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the temperature at a depth

of 50 cm below the soil surface is higher than 8 oC.

Calcic Udic Haplustepts

KEDS. Other Haplustepts that have a calcic horizon that has

its upper boundary within 100 cm of the mineral soil surface.

Calcic Haplustepts
184 Keys to Soil Taxonomy

KEDT. Other Haplustepts that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid soil temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the cumulative days per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for six-tenths or more of the cumulative days per year

when the temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some part for six-tenths or more of the

cumulative days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Haplustepts

KEDU. Other Haplustepts that have a base saturation (by sum

of cations) of less than 60 percent in some horizon between

either an Ap horizon or a depth of 25 cm from the mineral soil

surface, whichever is deeper, and either a depth of 75 cm below

the mineral soil surface or a densic, lithic, or paralithic contact,

whichever is shallower.

Dystric Haplustepts

KEDV. Other Haplustepts that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid soil temperature regime and a moisture control

section that in normal years is dry in some or all parts for

fewer than 105 cumulative days per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for less than four-tenths of the cumulative days per year

when the temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Udic Haplustepts

KEDW. Other Haplustepts.

Typic Haplustepts

Xerepts

Key to Great Groups

KFA. Xerepts that have a duripan that has its upper boundary

within 100 cm of the mineral soil surface.

Durixerepts, p. 185

KFB. Other Xerepts that both:

1. Have a calcic horizon with its upper boundary

within 100 cm of the mineral soil surface or a petrocalcic

horizon with its upper boundary within 150 cm of the

mineral soil surface; and

2. Are calcareous in all parts above the calcic or

petrocalcic horizon, after the soil between the mineral soil

surface and a depth of 18 cm has been mixed.

Calcixerepts, p. 184

KFC. Other Xerepts that have a fragipan that has its upper

boundary within 100 cm of the mineral soil surface.

Fragixerepts, p. 187

KFD. Other Xerepts that have both of the following:

1. No free carbonates within 200 cm of the mineral soil

surface; and

2. A base saturation (by NH4

OAc) of less than 60 percent

in all horizons at a depth between 25 and 75 cm from the

mineral soil surface.

Dystroxerepts, p. 186

KFE. Other Xerepts.

Haploxerepts, p. 188

Calcixerepts

Key to Subgroups

KFBA. Calcixerepts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Calcixerepts

KFBB. Other Calcixerepts that have one or both of the

following:
Inceptisols 185

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1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Calcixerepts

KFBC. Other Calcixerepts that have a petrocalcic horizon that

has its upper boundary within 100 cm of the mineral soil

surface.

Petrocalcic Calcixerepts

KFBD. Other Calcixerepts that have an exchangeable sodium

percentage of 15 or more (or a sodium adsorption ratio [SAR]

of 13 or more) in one or more subhorizons within 100 cm of the

mineral soil surface.

Sodic Calcixerepts

KFBE. Other Calcixerepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Calcixerepts

KFBF. Other Calcixerepts that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Calcixerepts

KFBG. Other Calcixerepts.

Typic Calcixerepts

Durixerepts

Key to Subgroups

KFAA. Durixerepts that have both:

1. In one or more horizons above the duripan and

within 30 cm of the mineral soil surface, distinct or

prominent redox concentrations and also aquic conditions

for some time in normal years (or artificial drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more, above the duripan and within 75 cm of the

mineral soil surface, one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Durixerepts

KFAB. Other Durixerepts that have, throughout one or more

horizons with a total thickness of 18 cm or more, above the

duripan and within 75 cm of the mineral soil surface, a fineearth fraction with both a bulk density of 1.0 g/cm3

 or less,

measured at 33 kPa water retention, and Al plus 1/2 Fe

percentages (by ammonium oxalate) totaling more than 1.0.

Andic Durixerepts

KFAC. Other Durixerepts that have, throughout one or more

horizons with a total thickness of 18 cm or more, above the

duripan and within 75 cm of the mineral soil surface, one or

both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Durixerepts

KFAD. Other Durixerepts that have, in one or more horizons

above the duripan and within 30 cm of the mineral soil surface,

distinct or prominent redox concentrations and also aquic
186 Keys to Soil Taxonomy

conditions for some time in normal years (or artificial

drainage).

Aquic Durixerepts

KFAE. Other Durixerepts that have a duripan that is strongly

cemented or less cemented in all subhorizons.

Entic Durixerepts

KFAF. Other Durixerepts.

Typic Durixerepts

Dystroxerepts

Key to Subgroups

KFDA. Dystroxerepts that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. An umbric or mollic epipedon.

Humic Lithic Dystroxerepts

KFDB. Other Dystroxerepts that have a lithic contact within

50 cm of the mineral soil surface.

Lithic Dystroxerepts

KFDC. Other Dystroxerepts that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Dystroxerepts

KFDD. Other Dystroxerepts that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction with both

a bulk density of 1.0 g/cm3

 or less, measured at 33 kPa water

retention, and Al plus 1/2 Fe percentages (by ammonium

oxalate) totaling more than 1.0.

Andic Dystroxerepts

KFDE. Other Dystroxerepts that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelik fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Dystroxerepts

KFDF. Other Dystroxerepts that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions in normal years (or artificial drainage).

Fragiaquic Dystroxerepts

KFDG. Other Dystroxerepts that have a slope of less than 25

percent; and

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Either:

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densic, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a

depth of 125 cm below the mineral soil surface or a
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densic, lithic, or paralithic contact, whichever is

shallower.

Fluvaquentic Dystroxerepts

KFDH. Other Dystroxerepts that have, in one or more

horizons within 75 cm of the mineral soil surface, redox

depletions with chroma of 2 or less and also aquic conditions

for some time in normal years (or artificial drainage).

Aquic Dystroxerepts

KFDI. Other Dystroxerepts that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Dystroxerepts

KFDJ. Other Dystroxerepts that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Dystroxerepts

KFDK. Other Dystroxerepts that have a slope of less than 25

percent; and

1. An umbric or mollic epipedon; and

2. Either:

a. At a depth of 125 cm below the mineral soil surface,

an organic-carbon content (Holocene age) of 0.2 percent

or more and no densc, lithic, or paralithic contact within

that depth; or

b. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either

a depth of 125 cm below the mineral soil surface or

a densic, lithic, or paralithic contact, whichever is

shallower.

Fluventic Humic Dystroxerepts

KFDL. Other Dystroxerepts that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or

more and no densic, lithic, or paralithic contact within that

depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluventic Dystroxerepts

KFDM. Other Dystroxerepts that have an umbric or mollic

epipedon.

Humic Dystroxerepts

KFDN. Other Dystroxerepts.

Typic Dystroxerepts

Fragixerepts

Key to Subgroups

KFCA. Fragixerepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Fragixerepts

KFCB. Other Fragixerepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Fragixerepts

KFCC. Other Fragixerepts that have, in one or more horizons

within 30 cm of the mineral soil surface, distinct or prominent

redox concentrations and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Fragixerepts

KFCD. Other Fragixerepts that have an umbric or mollic

epipedon.

Humic Fragixerepts

KFCE. Other Fragixerepts.

Typic Fragixerepts
188 Keys to Soil Taxonomy

Haploxerepts

Key to Subgroups

KFEA. Haploxerepts that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. An umbric or mollic epipedon.

Humic Lithic Haploxerepts

KFEB. Other Haploxerepts that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Haploxerepts

KFEC. Other Haploxerepts that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Haploxerepts

KFED. Other Haploxerepts that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Haploxerepts

KFEE. Other Haploxerepts that have both:

1. In one or more horizons with a total thickness of 18 cm

or more within 75 cm of the mineral soil surface, a fine-earth

fraction with both a bulk density of 1.0 g/cm3

 or less,

measured at 33 kPa water retention, and Al plus 1/2 Fe

percentages (by ammonium oxalate) totaling more than 1.0.

2. Saturation with water within 100 cm of the mineral soil

surface in normal years for either or both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Andic Oxyaquic Haploxerepts

KFEF. Other Haploxerepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haploxerepts

KFEG. Other Haploxerepts that have both:

1. Saturation with water within 100 cm of the mineral soil

surface in normal years for either or both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1

/2 Fe percentages extracted by

ammonium oxalate) times 60] plus the volcanic glass

(percent) is equal to 30 or more.

Oxyaquic Vitrandic Haploxerepts

KFEH. Other Haploxerepts that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or
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2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Haploxerepts

KFEI. Other Haploxerepts that have a gypsic horizon within

100 cm of the mineral soil surface.

Gypsic Haploxerepts

KFEJ. Other Haploxerepts that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Haploxerepts

KFEK. Other Haploxerepts that have lamellae (two or more)

within 200 cm of the mineral soil surface.

Lamellic Haploxerepts

KFEL. Other Haploxerepts that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Haploxerepts

KFEM. Other Haploxerepts that have a slope of less than 25

percent; and either

1. At a depth of 125 cm below the mineral soil surface, an

organic-carbon content (Holocene age) of 0.2 percent or more

and no densic, lithic, or paralithic contact within that depth; or

2. An irregular decrease in organic-carbon content

(Holocene age) between a depth of 25 cm and either a depth

of 125 cm below the mineral soil surface or a densic, lithic,

or paralithic contact, whichever is shallower.

Fluventic Haploxerepts

KFEN. Other Haploxerepts that have a calcic horizon or

identifiable secondary carbonates within one of the following

particle-size class and depth combinations:

1. A sandy or sandy-skeletal particle-size class and

within 150 cm of the mineral soil surface; or

2. A clayey, clayey-skeletal, fine, or very-fine

particle-size class and within 90 cm of the mineral soil

surface; or

3. Any other particle-size class and within 110 cm of the

mineral soil surface.

Calcic Haploxerepts

KFEO. Other Haploxerepts that have an umbric or mollic

epipedon.

Humic Haploxerepts

KFEP. Other Haploxerepts.

Typic Haploxerepts

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Key to Suborders

IA. Mollisols that have:

1. An argillic or natric horizon; and

2. An albic horizon that has chroma of 2 or less and is 2.5

cm or more thick, has its lower boundary 18 cm or more

below the mineral soil surface, and either lies directly below

the mollic epipedon or separates horizons that together meet

all of the requirements for a mollic epipedon; and

3. In one or more subhorizons of the albic horizon and/or

of the argillic or natric horizon and within 100 cm of the

mineral soil surface, redox concentrations in the form of

masses or concretions, or both, and also aquic conditions for

some time in normal years (or artificial drainage).

Albolls, p. 192

IB. Other Mollisols that have, in a layer above a densic, lithic,

or paralithic contact or in a layer at a depth between 40 and 50

cm from the mineral soil surface, whichever is shallower, aquic

conditions for some time in normal years (or artificial drainage)

and one or more of the following:

1. A histic epipedon overlying the mollic epipedon; or

2. An exchangeable sodium percentage (ESP) of 15 or

more (or a sodium adsorption ratio [SAR] of 13 or more) in

the upper part of the mollic epipedon and a decrease in ESP

(or SAR) values with increasing depth below 50 cm from the

mineral soil surface; or

3. A calcic or petrocalcic horizon that has its upper

boundary within 40 cm of the mineral soil surface; or

4. A mollic epipedon, with chroma of 1 or less, that

extends to a lithic contact within 30 cm of the mineral soil

surface; or

5. One of the following colors:

a. Chroma of 1 or less in the lower part of the mollic

epipedon;1 and either

(1) Distinct or prominent redox concentrations in the

lower part of the mollic epipedon; or

(2) Either directly below the mollic epipedon or

within 75 cm of the mineral soil surface if a calcic

horizon intervenes, a color value, moist, of 4 or more

and one of the following:

(a) 50 percent or more chroma of 1 on faces of

peds or in the matrix, hue of 10YR or redder, and

redox concentrations; or

(b) 50 percent or more chroma of 2 or less on

faces of peds or in the matrix, hue of 2.5Y, and

redox concentrations; or

(c) 50 percent or more chroma of 1 on faces of

peds or in the matrix and hue of 2.5Y or yellower; or

(d) 50 percent or more chroma of 3 or less on

faces of peds or in the matrix, hue of 5Y, and redox

concentrations; or

(e) 50 percent or more chroma of 0 on faces of

peds or in the matrix; or

(f) Hue of 5GY, 5G, 5BG, or 5B; or

(g) Any color if it results from uncoated sand

grains; or

b. Chroma of 2 in the lower part of the mollic epipedon;

and either

(1) Distinct or prominent redox concentrations in the

lower part of the mollic epipedon; or

(2) Directly below the mollic epipedon, one of the

following matrix colors:

(a) A color value, moist, of 4, chroma of 2, and

some redox depletions with a color value, moist, of

4 or more and chroma of 1 or less; or

(b) A color value, moist, of 5 or more, chroma of

2 or less, and redox concentrations; or

(c) A color value, moist, of 4 and chroma of 1 or

less; or

6. At a depth between 40 and 50 cm from the mineral soil

surface, enough active ferrous iron to give a positive reaction

to alpha,alpha-dipyridyl at a time when the soil is not being

irrigated.

Aquolls, p. 193

CHAPTER 12

Mollisols

1 If the mollic epipedon extends to a lithic contact within 30 cm of the mineral soil

surface, the requirement for redoximorphic features is waived.
192 Keys to Soil Taxonomy

IC. Other Mollisols that:

1. Have a mollic epipedon less than 50 cm thick;

and

2. Do not have an argillic or calcic horizon; and

3. Have, either within or directly below the mollic

epipedon, mineral soil materials less than 7.5 cm in diameter

that have a CaCO3 equivalent of 40 percent or more; and

4. Have either or both a udic moisture regime or a cryic

soil temperature regime.

Rendolls, p. 201

ID. Other Mollisols that have, in normal years, a mean annual

soil temperature of 0 o

C or colder and a mean summer soil

temperature that:

1. Is 8 oC or colder if there is no O horizon; or

2. Is 5 oC or colder if there is an O horizon.

Gelolls, p. 200

IE. Other Mollisols that have a cryic soil temperature regime.

Cryolls, p. 197

IF. Other Mollisols that have either a xeric moisture regime or

an aridic moisture regime that borders on xeric.

Xerolls, p. 224

IG. Other Mollisols that have either an ustic moisture regime

or an aridic moisture regime that borders on ustic.

Ustolls, p. 209

IH. Other Mollisols.

Udolls, p. 201

Albolls

Key to Great Groups

IAA. Albolls that have a natric horizon.

Natralbolls, p. 193

IAB. Other Albolls.

Argialbolls, p. 192

Argialbolls

Key to Subgroups

IABA. Argialbolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. If not irrigated, a moisture control section that in normal

years is dry in all parts for 45 or more consecutive days

during the 120 days following the summer solstice.

Xerertic Argialbolls

IABB. Other Argialbolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Argialbolls

IABC. Other Argialbolls that:

1. Do not have an abrupt textural change from the albic to

the argillic horizon; and

2. If not irrigated, have a moisture control section that in

normal years is dry in all parts for 45 or more consecutive

days during the 120 days following the summer solstice.

Argiaquic Xeric Argialbolls

IABD. Other Argialbolls that do not have an abrupt textural

change from the albic to the argillic horizon.

Argiaquic Argialbolls

IABE. Other Argialbolls that, if not irrigated, have a moisture

control section that in normal years is dry in all parts for 45 or

more consecutive days during the 120 days following the

summer solstice.

Xeric Argialbolls

IABF. Other Argialbolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or
Mollisols 193

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2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Argialbolls

IABG. Other Argialbolls.

Typic Argialbolls

Natralbolls

Key to Subgroups

IAAA. Natralbolls that have visible crystals of gypsum

and/or more soluble salts within 40 cm of the mineral soil

surface.

Leptic Natralbolls

IAAB. Other Natralbolls.

Typic Natralbolls

Aquolls

Key to Great Groups

IBA. Aquolls that have a cryic soil temperature regime.

Cryaquolls, p. 194

IBB. Other Aquolls that have a duripan that has its upper

boundary within 100 cm of the mineral soil surface.

Duraquolls, p. 194

IBC. Other Aquolls that have a natric horizon.

Natraquolls, p. 196

IBD. Other Aquolls that have a calcic or gypsic horizon that

has its upper boundary within 40 cm of the mineral soil surface

but do not have an argillic horizon unless it is a buried horizon.

Calciaquolls, p. 193

IBE. Other Aquolls that have an argillic horizon.

Argiaquolls, p. 193

IBF. Other Aquolls that have episaturation.

Epiaquolls, p. 195

IBG. Other Aquolls.

Endoaquolls, p. 194

Argiaquolls

Key to Subgroups

IBEA. Argiaquolls that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm.

Arenic Argiaquolls

IBEB. Other Argiaquolls that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 100 cm or more.

Grossarenic Argiaquolls

IBEC. Other Argiaquolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Argiaquolls

IBED. Other Argiaquolls that have an argillic horizon that,

with increasing depth, has a clay increase of 20 percent or more

(absolute, in the fine-earth fraction) within its upper 7.5 cm.

Abruptic Argiaquolls

IBEE. Other Argiaquolls.

Typic Argiaquolls

Calciaquolls

Key to Subgroups

IBDA. Calciaquolls that have a petrocalcic horizon that has its

upper boundary within 100 cm of the mineral soil surface.

Petrocalcic Calciaquolls

IBDB. Other Calciaquolls that have 50 percent or more

chroma of 3 or more on faces of peds or in the matrix of one or

more horizons within 75 cm of the mineral soil surface or that

have the following colors directly below the mollic epipedon:

1. Hue of 2.5Y or yellower and chroma of 3 or more; or

2. Hue of 10YR or redder and chroma of 2 or more; or

3. Hue of 2.5Y or yellower and chroma of 2 or more if

there are no distinct or prominent redox concentrations.

Aeric Calciaquolls
194 Keys to Soil Taxonomy

IBDC. Other Calciaquolls.

Typic Calciaquolls

Cryaquolls

Key to Subgroups

IBAA. Cryaquolls that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Cryaquolls

IBAB. Other Cryaquolls that have a histic epipedon.

Histic Cryaquolls

IBAC. Other Cryaquolls that have a buried layer of organic

soil materials, 20 cm or more thick, that has its upper boundary

within 100 cm of the mineral soil surface.

Thapto-Histic Cryaquolls

IBAD. Other Cryaquolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Cryaquolls

IBAE. Other Cryaquolls that have an argillic horizon.

Argic Cryaquolls

IBAF. Other Cryaquolls that have a calcic horizon either

within or directly below the mollic epipedon.

Calcic Cryaquolls

IBAG. Other Cryaquolls that have a mollic epipedon 50 cm or

more thick.

Cumulic Cryaquolls

IBAH. Other Cryaquolls.

Typic Cryaquolls

Duraquolls

Key to Subgroups

IBBA. Duraquolls that have a natric horizon.

Natric Duraquolls

IBBB. Other Duraquolls that have, above the duripan, one or

both of the following:

1. Cracks that are 5 mm or more wide through a thickness

of 30 cm or more for some time in normal years and

slickensides or wedge-shaped aggregates in a layer 15 cm or

more thick; or

2. A linear extensibility of 6.0 cm or more.

Vertic Duraquolls

IBBC. Other Duraquolls that have an argillic horizon.

Argic Duraquolls

IBBD. Other Duraquolls.

Typic Duraquolls

Endoaquolls

Key to Subgroups

IBGA. Endoaquolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Endoaquolls

IBGB. Other Endoaquolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the
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mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. A mollic epipedon 60 cm or more thick.

Cumulic Vertic Endoaquolls

IBGC. Other Endoaquolls that have both of the following:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. A slope of less than 25 percent; and either

a. An organic-carbon content of 0.3 percent or more in

all horizons within 125 cm of the mineral soil surface; or

b. An irregular decrease in organic-carbon content from

a depth of 25 cm to a depth of 125 cm or to a densic,

lithic, or paralithic contact if shallower.

Fluvaquentic Vertic Endoaquolls

IBGD. Other Endoaquolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Endoaquolls

IBGE. Other Endoaquolls that have a histic epipedon.

Histic Endoaquolls

IBGF. Other Endoaquolls that have a buried layer of organic

soil materials, 20 cm or more thick, that has its upper boundary

within 100 cm of the mineral soil surface.

Thapto-Histic Endoaquolls

IBGG. Other Endoaquolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Endoaquolls

IBGH. Other Endoaquolls that have a horizon, 15 cm or more

thick within 100 cm of the mineral soil surface, that either has

20 percent or more (by volume) durinodes or is brittle and has a

firm rupture-resistance class when moist.

Duric Endoaquolls

IBGI. Other Endoaquolls that have a mollic epipedon 60 cm

or more thick.

Cumulic Endoaquolls

IBGJ. Other Endoaquolls that have a slope of less than 25

percent; and either

1. An organic-carbon content of 0.3 percent or more in all

horizons within 125 cm of the mineral soil surface; or

2. An irregular decrease in organic-carbon content from a

depth of 25 cm to a depth of 125 cm or to a densic, lithic, or

paralithic contact if shallower.

Fluvaquentic Endoaquolls

IBGK. Other Endoaquolls.

Typic Endoaquolls

Epiaquolls

Key to Subgroups

IBFA. Epiaquolls that have both of the following:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or
196 Keys to Soil Taxonomy

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. A mollic epipedon 60 cm or more thick.

Cumulic Vertic Epiaquolls

IBFB. Other Epiaquolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. A slope of less than 25 percent; and either

a. An organic-carbon content of 0.3 percent or more in

all horizons within 125 cm of the mineral soil surface; or

b. An irregular decrease in organic-carbon content from

a depth of 25 cm to a depth of 125 cm or to a densic,

lithic, or paralithic contact if shallower.

Fluvaquentic Vertic Epiaquolls

IBFC. Other Epiaquolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Epiaquolls

IBFD. Other Epiaquolls that have a histic epipedon.

Histic Epiaquolls

IBFE. Other Epiaquolls that have a buried layer of organic

soil materials, 20 cm or more thick, that has its upper boundary

within 100 cm of the mineral soil surface.

Thapto-Histic Epiaquolls

IBFF. Other Epiaquolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Epiaquolls

IBFG. Other Epiaquolls that have a horizon, 15 cm or more

thick within 100 cm of the mineral soil surface, that either has

20 percent or more (by volume) durinodes or is brittle and has a

firm rupture-resistance class when moist.

Duric Epiaquolls

IBFH. Other Epiaquolls that have a mollic epipedon 60 cm or

more thick.

Cumulic Epiaquolls

IBFI. Other Epiaquolls that have a slope of less than 25

percent; and either

1. An organic-carbon content of 0.3 percent or more in all

horizons within 125 cm of the mineral soil surface; or

2. An irregular decrease in organic-carbon content from a

depth of 25 cm to a depth of 125 cm or to a densic, lithic, or

paralithic contact if shallower.

Fluvaquentic Epiaquolls

IBFJ. Other Epiaquolls.

Typic Epiaquolls

Natraquolls

Key to Subgroups

IBCA. Natraquolls that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that
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has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Natraquolls

IBCB. Other Natraqolls that have a glossic horizon or

interfingering of albic materials into the natric horizon.

Glossic Natraquolls

IBCC. Other Natraquolls.

Typic Natraquolls

Cryolls

Key to Great Groups

IEA. Cryolls that have a duripan that has its upper boundary

within 100 cm of the mineral soil surface.

Duricryolls, p. 198

IEB. Other Cryolls that have a natric horizon.

Natricryolls, p. 200

IEC. Other Cryolls that have both:

1. An argillic horizon that has its upper boundary 60 cm or

more below the mineral soil surface; and

2. A texture finer than loamy fine sand in all horizons

above the argillic horizon.

Palecryolls, p. 200

IED. Other Cryolls that have an argillic horizon.

Argicryolls, p. 197

IEE. Other Cryolls that:

1. Have a calcic or petrocalcic horizon that has its

upper boundary within 100 cm of the mineral soil surface;

and

2. In all parts above the calcic or petrocalcic horizon, after

the materials between the soil surface and a depth of 18 cm

have been mixed, either are calcareous or have a texture of

loamy fine sand or coarser.

Calcicryolls, p. 198

IEF. Other Cryolls.

Haplocryolls, p. 199

Argicryolls

Key to Subgroups

IEDA. Argicryolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Argicryolls

IEDB. Other Argicryolls that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Argicryolls

IEDC. Other Argicryolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Argicryolls

IEDD. Other Argicryolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Argicryolls

IEDE. Other Argicryolls that have an argillic horizon that,

with increasing depth, has a clay increase of 20 percent or more

(absolute, in the fine-earth fraction) within its upper 7.5 cm.

Abruptic Argicryolls

IEDF. Other Argicryolls that have, in one or more horizons
198 Keys to Soil Taxonomy

within 100 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Argicryolls

IEDG. Other Argicryolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Argicryolls

IEDH. Other Argicryolls that have both:

1. A mollic epipedon that is 40 cm or more thick and has a

texture finer than loamy fine sand; and

2. A calcic horizon within 100 cm of the mineral soil

surface.

Calcic Pachic Argicryolls

IEDI. Other Argicryolls that have a mollic epipedon that is

40 cm or more thick and has a texture finer than loamy fine

sand.

Pachic Argicryolls

IEDJ. Other Argicryolls that have a calcic horizon within 100

cm of the mineral soil surface.

Calcic Argicryolls

IEDK. Other Argicryolls that have either:

1. Above the argillic horizon, an albic horizon or a horizon

that has color values too high for a mollic epipedon and

chroma too high for an albic horizon; or

2. A glossic horizon, or interfingering of albic materials

into the upper part of the argillic horizon, or skeletans of

clean silt and sand covering 50 percent or more of the faces

of peds in the upper 5 cm of the argillic horizon.

Alfic Argicryolls

IEDL. Other Argicryolls that have an ustic moisture

regime.

Ustic Argicryolls

IEDM. Other Argicryolls that have a xeric moisture

regime.

Xeric Argicryolls

IEDN. Other Argicryolls.

Typic Argicryolls

Calcicryolls

Key to Subgroups

IEEA. Calcicryolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Calcicryolls

IEEB. Other Calcicryolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumiceous, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Calcicryolls

IEEC. Other Calcicryolls that have a petrocalcic horizon that

has its upper boundary within 100 cm of the mineral soil surface.

Petrocalcic Calcicryolls

IEED. Other Calcicryolls that have a mollic epipedon that is 40

cm or more thick and has a texture finer than loamy fine sand.

Pachic Calcicryolls

IEEE. Other Calcicryolls that have an ustic moisture regime.

Ustic Calcicryolls

IEEF. Other Calcicryolls that have a xeric moisture regime.

Xeric Calcicryolls

IEEG. Other Calcicryolls.

Typic Calcicryolls

Duricryolls

Key to Subgroups

IEAA. Duricryolls that have an argillic horizon.

Argic Duricryolls

IEAB. Other Duricryolls that have a calcic horizon above the

duripan.

Calcic Duricryolls
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IEAC. Other Duricryolls.

Typic Duricryolls

Haplocryolls

Key to Subgroups

IEFA. Haplocryolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haplocryolls

IEFB. Other Haplocryolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Haplocryolls

IEFC. Other Haplocryolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haplocryolls

IEFD. Other Haplocryolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Haplocryolls

IEFE. Other Haplocryolls that have:

1. A mollic epipedon that is 40 cm or more thick and has a

texture finer than loamy fine sand; and

2. An irregular decrease in organic-carbon content from a

depth of 25 cm below the mineral soil surface to a depth of

125 cm or to a densic, lithic, or paralithic contact if

shallower; and

3. A slope of less than 25 percent; and

4. In one or more horizons within 100 cm of the mineral

soil surface, distinct or prominent redox concentrations and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Cumulic Haplocryolls

IEFF. Other Haplocryolls that have:

1. A mollic epipedon that is 40 cm or more thick and has a

texture finer than loamy fine sand; and

2. An irregular decrease in organic-carbon content from a

depth of 25 cm below the mineral soil surface to a depth of

125 cm or to a densic, lithic, or paralithic contact if

shallower; and

3. A slope of less than 25 percent.

Cumulic Haplocryolls

IEFG. Other Haplocryolls that have both:

1. A slope of less than 25 percent; and either

a. An organic-carbon content of 0.3 percent or more at a

depth of 125 cm below the mineral soil surface; or

b. An irregular decrease in organic-carbon content from

a depth of 25 cm to a depth of 125 cm or to a densic,

lithic, or paralithic contact if shallower; and

2. In one or more horizons within 100 cm of the mineral

soil surface, distinct or prominent redox concentrations and

also aquic conditions for some time in normal years (or

artificial drainage).

Fluvaquentic Haplocryolls

IEFH. Other Haplocryolls that have, in one or more horizons

within 100 cm of the mineral soil surface, distinct or prominent

redox concentrations and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Haplocryolls

IEFI. Other Haplocryolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplocryolls

IEFJ. Other Haplocryolls that have both:

1. A mollic epipedon that is 40 cm or more thick and has a

texture finer than loamy fine sand; and
200 Keys to Soil Taxonomy

2. A calcic horizon within 100 cm of the mineral soil

surface.

Calcic Pachic Haplocryolls

IEFK. Other Haplocryolls that have a mollic epipedon that is

40 cm or more thick and has a texture finer than loamy fine sand.

Pachic Haplocryolls

IEFL. Other Haplocryolls that have a slope of less than 25

percent; and either

1. An organic-carbon content of 0.3 percent or more at a

depth of 125 cm below the mineral soil surface; or

2. An irregular decrease in organic-carbon content from a

depth of 25 cm to a depth of 125 cm or to a densic, lithic, or

paralithic contact if shallower.

Fluventic Haplocryolls

IEFM. Other Haplocryolls that have a calcic horizon within

100 cm of the mineral soil surface.

Calcic Haplocryolls

IEFN. Other Haplocryolls that have an ustic moisture regime.

Ustic Haplocryolls

IEFO. Other Haplocryolls that have a xeric moisture regime.

Xeric Haplocryolls

IEFP. Other Haplocryolls.

Typic Haplocryolls

Natricryolls

Key to Subgroups

IEBA. All Natricryolls.

Typic Natricryolls

Palecryolls

Key to Subgroups

IECA. Palecryolls that have, in one or more horizons within

100 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Palecryolls

IECB. Other Palecryolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Palecryolls

IECC. Other Palecryolls that have an argillic horizon that,

with increasing depth, has a clay increase of 20 percent or more

(absolute, in the fine-earth fraction) within its upper 7.5 cm.

Abruptic Palecryolls

IECD. Other Palecryolls that have a mollic epipedon that is

40 cm or more thick and has a texture finer than loamy fine

sand.

Pachic Palecryolls

IECE. Other Palecryolls that have an ustic moisture regime.

Ustic Palecryolls

IECF. Other Palecryolls that have a xeric moisture regime.

Xeric Palecryolls

IECG. Other Palecryolls.

Typic Palecryolls

Gelolls

Key to Great Groups

IDA. All Gelolls.

Haplogelolls, p. 200

Haplogelolls

Key to Subgroups

IDAA. Haplogelolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haplogelolls

IDAB. Other Haplogelolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haplogelolls

IDAC. Other Haplogelolls that have, in one or more horizons

within 100 cm of the mineral soil surface, distinct or prominent

redox concentrations and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Haplogelolls

IDAD. Other Haplogelolls that have:

1. A mollic epipedon that is 40 cm or more thick and has a

texture finer than loamy fine sand; and

2. An irregular decrease in organic-carbon content from a
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depth of 25 cm below the mineral soil surface to a depth of 125

cm or a densic, lithic, or paralithic contact if shallower.

Cumulic Haplogelolls

IDAE. Other Haplogelolls.

Typic Haplogelolls

Rendolls

Key to Great Groups

ICA. Rendolls that have a cryic soil temperature regime.

Cryrendolls, p. 201

ICB. Other Rendolls.

Haprendolls, p. 201

Cryrendolls

Key to Subgroups

ICAA. Cryrendolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Cryrendolls

ICAB. Other Cryrendolls.

Typic Cryrendolls

Haprendolls

Key to Subgroups

ICBA. Haprendolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haprendolls

ICBB. Other Haprendolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Haprendolls

ICBC. Other Haprendolls that have a cambic horizon.

Inceptic Haprendolls

ICBD. Other Haprendolls that have a color value, dry, of 6 or

more either in the upper 18 cm of the mollic epipedon, after

mixing, or in an Ap horizon 18 cm or more thick.

Entic Haprendolls

ICBE. Other Haprendolls.

Typic Haprendolls

Udolls

Key to Great Groups

IHA. Udolls that have a natric horizon.

Natrudolls, p. 207

IHB. Other Udolls that:

1. Have a calcic or petrocalcic horizon that has its upper

boundary within 100 cm of the mineral soil surface; and

2. Do not have an argillic horizon above the calcic or

petrocalcic horizon; and

3. In all parts above the calcic or petrocalcic horizon, after

the materials between the soil surface and a depth of 18 cm

have been mixed, either are calcareous or have a texture of

loamy fine sand or coarser.

Calciudolls, p. 204

IHC. Other Udolls that have one or more of the following:

1. A petrocalcic horizon that has its upper boundary within

150 cm of the mineral soil surface; or

2. All of the following:

a. No densic, lithic, or paralithic contact within 150 cm

of the mineral soil surface; and

b. Within 150 cm of the mineral soil surface, a clay

decrease, with increasing depth, of less than 20 percent

(relative) from the maximum clay content (noncarbonate

clay); and

c. An argillic horizon with one or more of the

following:

(1) In 50 percent or more of the matrix of one or

more subhorizons in its lower half, hue of 7.5YR or

redder and chroma of 5 or more; or

(2) In 50 percent or more of the matrix of horizons

that total more than one-half the total thickness, hue of

2.5YR or redder, a value, moist, of 3 or less, and a

value, dry, of 4 or less; or

(3) Many redox concentrations with hue of 5YR or

redder or chroma of 6 or more, or both, in one or more

subhorizons; or

3. A frigid temperature regime; and both
202 Keys to Soil Taxonomy

a. An argillic horizon that has its upper boundary 60 cm

or more below the mineral soil surface; and

b. A texture finer than loamy fine sand in all horizons

above the argillic horizon.

Paleudolls, p. 208

IHD. Other Udolls that have an argillic horizon.

Argiudolls, p. 202

IHE. Other Udolls that have a mollic epipedon that:

1. Either below an Ap horizon or below a depth of 18 cm

from the mineral soil surface, contains 50 percent or more

(by volume) wormholes, wormcasts, or filled animal

burrows; and

2. Either rests on a lithic contact or has a transition zone to

the underlying horizon in which 25 percent or more of the

soil volume consists of discrete wormholes, wormcasts, or

animal burrows filled with material from the mollic epipedon

and from the underlying horizon.

Vermudolls, p. 208

IHF. Other Udolls.

Hapludolls, p. 205

Argiudolls

Key to Subgroups

IHDA. Argiudolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Argiudolls

IHDB. Other Argiudolls that have both:

1. Aquic conditions for some time in normal years (or

artificial drainage) either:

a. Within 40 cm of the mineral soil surface, in horizons

that also have redoximorphic features; or

b. Within 75 cm of the mineral soil surface, in one or

more horizons with a total thickness of 15 cm or more

that have one or more of the following:

(1) A color value, moist, of 4 or more and redox

depletions with chroma of 2 or less; or

(2) Hue of 10YR or redder and chroma of 2 or less; or

(3) Hue of 2.5Y or yellower and chroma of 3 or less;

and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Aquertic Argiudolls

IHDC. Other Argiudolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. In normal years saturation with water in one or more

layers within 100 cm of the mineral soil surface for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Oxyaquic Vertic Argiudolls

IHDD. Other Argiudolls that have:

1. A mollic epipedon that has a texture finer than loamy

fine sand and that is either:

a. 40 cm or more thick in a frigid temperature regime; or

b. 50 cm or more thick; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower.

Pachic Vertic Argiudolls

IHDE. Other Argiudolls that have:

1. Above the argillic horizon, an albic horizon or a horizon
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that has color values too high for a mollic epipedon and

chroma too high for an albic horizon; or

2. A glossic horizon, or interfingering of albic materials

into the upper part of the argillic horizon, or skeletans of

clean silt and sand covering 50 percent or more of the faces

of peds in the upper 5 cm of the argillic horizon; and

3. Either:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Alfic Vertic Argiudolls

IHDF. Other Argiudolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Argiudolls

IHDG. Other Argiudolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Argiudolls

IHDH. Other Argiudolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Argiudolls

IHDI. Other Agriudolls that have both:

1. Aquic conditions for some time normal years (or

artificial drainage) either:

a. Within 40 cm of the mineral soil surface, in horizons

that also have redoximorphic features; or

b. Within 75 cm of the mineral soil surface, in one or

more horizons with a total thickness of 15 cm or more

that have one or more of the following:

(1) A color value, moist, of 4 or more and redox

depletions with chroma of 2 or less; or

(2) Hue of 10YR or redder and chroma of 2 or less;

or

(3) Hue of 2.5Y or yellower and chroma of 3 or less;

and

2. A mollic epipedon that has a texture finer than loamy

fine sand and that is either:

a. 40 cm or more thick in a frigid temperature regime; or

b. 50 cm or more thick.

Aquic Pachic Agriudolls

IHDJ. Other Argiudolls that have a mollic epipedon that has a

texture finer than loamy fine sand and that is either:

1. 40 cm or more thick in a frigid temperature regime; or

2. 50 cm or more thick.

Pachic Argiudolls

IHDK. Other Argiudolls that have aquic conditions for some

time in normal years (or artificial drainage) either:

1. Within 40 cm of the mineral soil surface, in horizons

that also have redoximorphic features; or

2. Within 75 cm of the mineral soil surface, in one or more

horizons with a total thickness of 15 cm or more that have

one or more of the following:

a. A color value, moist, of 4 or more and redox

depletions with chroma of 2 or less; or

b. Hue of 10YR or redder and chroma of 2 or less; or

c. Hue of 2.5Y or yellower and chroma of 3 or less.

Aquic Argiudolls

IHDL. Other Argiudolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:
204 Keys to Soil Taxonomy

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Argiudolls

IHDM. Other Argiudolls that have an argillic horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more

than 20 cm thick, each with an overlying eluvial horizon,

and above these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Argiudolls

IHDN. Other Argiudolls that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or throughout

the entire argillic horizon if it is less than 75 cm thick.

Psammentic Argiudolls

IHDO. Other Argiudolls that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 cm or more.

Arenic Argiudolls

IHDP. Other Argiudolls that have an argillic horizon that, with

increasing depth, has a clay increase of 20 percent or more

(absolute, in the fine-earth fraction) within its upper 7.5 cm.

Abruptic Argiudolls

IHDQ. Other Argiudolls that have:

1. Above the argillic horizon, an albic horizon or a horizon

that has color values too high for a mollic epipedon and

chroma too high for an albic horizon; or

2. A glossic horizon, or interfingering of albic materials

into the upper part of the argillic horizon, or skeletans of

clean silt and sand covering 50 percent or more of the faces

of peds in the upper 5 cm of the argillic horizon.

Alfic Argiudolls

IHDR. Other Argiudolls that have an apparent CEC of less

than 24 cmol(+)/kg clay (by 1N NH4

OAc pH 7) in 50 percent or

more either of the argillic horizon if less than 100 cm thick or

of its upper 100 cm.

Oxic Argiudolls

IHDS. Other Argiudolls that have a calcic horizon within 100

cm of the mineral soil surface.

Calcic Argiudolls

IHDT. Other Argiudolls.

Typic Argiudolls

Calciudolls

Key to Subgroups

IHBA. Calciudolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Calciudolls

IHBB. Other Calciudolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Calciudolls

IHBC. Other Calciudolls that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Calciudolls

IHBD. Other Calciudolls that have a slope of less than 25

percent; and either:

1. An organic-carbon content of 0.3 percent or more at a

depth of 125 cm below the mineral soil surface; or

2. An irregular decrease in organic-carbon content from a

depth of 25 cm to a depth of 125 cm or to a lithic or paralithic

contact if shallower.

Fluventic Calciudolls

IHBE. Other Calciudolls.

Typic Calciudolls
Mollisols 205

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Hapludolls

Key to Subgroups

IHFA. Hapludolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Hapludolls

IHFB. Other Hapludolls that have both:

1. Aquic conditions for some time in normal years (or

artificial drainage) either:

a. Within 40 cm of the mineral soil surface, in horizons

that also have redoximorphic features; or

b. Within 75 cm of the mineral soil surface, in one or

more horizons with a total thickness of 15 cm or more

that have one or more of the following:

(1) A color value, moist, of 4 or more and redox

depletions with chroma of 2 or less; or

(2) Hue of 10YR or redder and chroma of 2 or less;

or

(3) Hue of 2.5Y or yellower and chroma of 3 or less;

and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Aquertic Hapludolls

IHFC. Other Hapludolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. A mollic epipedon that has a texture finer than loamy

fine sand and that is either:

a. 40 cm or more thick in a frigid temperature regime; or

b. 50 cm or more thick.

Pachic Vertic Hapludolls

IHFD. Other Hapludolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Hapludolls

IHFE. Other Hapludolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and aluminum plus 1/2 iron percentages (by ammonium oxalate)

totaling more than 1.0.

Andic Hapludolls

IHFF. Other Hapludolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Hapludolls

IHFG. Other Hapludolls that have:

1. Either:

a. A frigid soil temperature regime and a mollic

epipedon 40 cm or more thick, of which less than 50

percent has a sandy or sandy-skeletal particle-size class,

and there is no densic or paralithic contact and no sandy

or sandy-skeletal particle-size class at a depth between 40

and 50 cm from the mineral soil surface; or

b. A mollic epipedon 60 cm or more thick, of which 50
206 Keys to Soil Taxonomy

percent or more of the thickness has a texture finer than

loamy fine sand; and

2. Either 0.3 percent or more organic carbon at a depth

of 125 cm below the mineral soil surface or an irregular

decrease in organic-carbon content from a depth of 25 cm to

a depth of 125 cm or to a densic, lithic, or paralithic contact

if shallower; and

3. A slope of 25 percent or less; and

4. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Aquic Cumulic Hapludolls

IHFH. Other Hapludolls that have:

1. Either:

a. A frigid soil temperature regime and a mollic

epipedon 40 cm or more thick, of which less than 50

percent has a sandy or sandy-skeletal particle-size class,

and there is no densic or paralithic contact and no sandy

or sandy-skeletal particle-size class at a depth between 40

and 50 cm from the mineral soil surface; or

b. A mollic epipedon 60 cm or more thick, of which 50

percent or more of the thickness has a texture finer than

loamy fine sand; and

2. Either 0.3 percent or more organic carbon at a depth

of 125 cm below the mineral soil surface or an irregular

decrease in organic-carbon content from a depth of 25 cm to

a depth of 125 cm or to a densic, lithic, or paralithic contact

if shallower; and

3. A slope of 25 percent or less.

Cumulic Hapludolls

IHFI. Other Hapludolls that have both:

1. Aquic conditions for some time in normal years (or

artificial drainage) either:

a. Within 40 cm of the mineral soil surface, in horizons

that also have redoximorphic features; or

b. Within 75 cm of the mineral soil surface, in one or

more horizons with a total thickness of 15 cm or more

that have one or more of the following:

(1) A color value, moist, of 4 or more and redox

depletions with chroma of 2 or less; or

(2) Hue of 10YR or redder and chroma of 2 or less; or

(3) Hue of 2.5Y or yellower and chroma of 3 or less;

and

2. A slope of less than 25 percent; and either

a. An organic-carbon content of 0.3 percent or more at a

depth of 125 cm below the mineral soil surface; or

b. An irregular decrease in organic-carbon content from

a depth of 25 cm to a depth of 125 cm or to a densic,

lithic, or paralithic contact if shallower.

Fluvaquentic Hapludolls

IHFJ. Other Hapludolls that have a slope of less than 25

percent; and either

1. An organic-carbon content of 0.3 percent or more at a

depth of 125 cm below the mineral soil surface; or

2. An irregular decrease in organic-carbon content from a

depth of 25 cm to a depth of 125 cm or to a densic, lithic, or

paralithic contact if shallower.

Fluventic Hapludolls

IHFK. Other Hapludolls that have both:

1. Aquic conditions for some time normal years (or

artificial drainage) either:

a. Within 40 cm of the mineral soil surface, in horizons

that also have redoximorphic features; or

b. Within 75 cm of the mineral soil surface, in one or

more horizons with a total thickness of 15 cm or more

that have one or more of the following:

(1) A color value, moist, of 4 or more and redox

depletions with chroma of 2 or less; or

(2) Hue of 10YR or redder and chroma of 2 or less; or

(3) Hue of 2.5Y or yellower and chroma of 3 or less;

and

2. A mollic epipedon that has a texture finer than loamy

fine sand and that is either:

a. 40 cm or more thick in a frigid temperature regime;

or

b. 50 cm or more thick.

Aquic Pachic Hapludolls

IHFL. Other Hapludolls that have a mollic epipedon that has a

texture finer than loamy fine sand and that is either:

1. 40 cm or more thick in a frigid temperature regime; or

2. 50 cm or more thick.

Pachic Hapludolls

IHFM. Other Hapludolls that have aquic conditions for some

time in normal years (or artificial drainage) either:
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1. Within 40 cm of the mineral soil surface, in horizons

that also have redoximorphic features; or

2. Within 75 cm of the mineral soil surface, in one or more

horizons with a total thickness of 15 cm or more that have

one or more of the following:

a. A color value, moist, of 4 or more and redox

depletions with chroma of 2 or less; or

b. Hue of 10YR or redder and chroma of 2 or less; or

c. Hue of 2.5Y or yellower and chroma of 3 or less.

Aquic Hapludolls

IHFN. Other Hapludolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Hapludolls

IHFO. Other Hapludolls that have both:

1. A mollic epipedon 60 cm or more thick that has a

texture finer than loamy fine sand and contains 50 percent or

more (by volume) wormholes, wormcasts, or filled animal

burrows either below an Ap horizon or below a depth of 18

cm from the mineral soil surface; and

2. Either do not have a cambic horizon and do not, in the

lower part of the mollic epipedon, meet all of the

requirements for a cambic horizon, except for the color

requirements, or have carbonates throughout either the

cambic horizon or the lower part of the mollic epipedon.

Vermic Hapludolls

IHFP. Other Hapludolls that have a calcic horizon within 100

cm of the mineral soil surface.

Calcic Hapludolls

IHFQ. Other Hapludolls that either:

1. Do not have a cambic horizon and do not, in any part of

the mollic epipedon below 25 cm from the mineral soil

surface, meet all of the requirements for a cambic horizon,

except for the color requirements; or

2. Have free carbonates throughout the cambic horizon or

in all parts of the mollic epipedon below a depth of 25 cm

from the mineral soil surface.

Entic Hapludolls

IHFR. Other Hapludolls.

Typic Hapludolls

Natrudolls

Key to Subgroups

IHAA. Natrudolls that have a petrocalcic horizon that has its

upper boundary within 100 cm of the mineral soil surface.

Petrocalcic Natrudolls

IHAB. Other Natrudolls that have both:

1. Visible crystals of gypsum and/or more soluble salts

within 40 cm of the mineral soil surface; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Leptic Vertic Natrudolls

IHAC. Other Natrudolls that have:

1. A glossic horizon or interfingering of albic materials

into the natric horizon; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm or

a densic, lithic, or paralithic contact, whichever is

shallower.

Glossic Vertic Natrudolls

IHAD. Other Natrudolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm
208 Keys to Soil Taxonomy

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Natrudolls

IHAE. Other Natrudolls that have visible crystals of gypsum

and/or more soluble salts within 40 cm of the mineral soil

surface.

Leptic Natrudolls

IHAF. Other Natrudolls that have a glossic horizon or

interfingering of albic materials into the natric horizon.

Glossic Natrudolls

IHAG. Other Natrudolls that have a calcic horizon within 100

cm of the mineral soil surface.

Calcic Natrudolls

IHAH. Other Natrudolls.

Typic Natrudolls

Paleudolls

Key to Subgroups

IHCA. Paleudolls that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Paleudolls

IHCB. Other Paleudolls that have a petrocalcic horizon within

150 cm of the mineral soil surface.

Petrocalcic Paleudolls

IHCC. Other Paleudolls that have both:

1. Aquic conditions for some time normal years (or

artificial drainage) either:

a. Within 40 cm of the mineral soil surface, in horizons

that also have redoximorphic features; or

b. Within 75 cm of the mineral soil surface, in one or

more horizons with a total thickness of 15 cm or more

that have one or more of the following:

(1) A color value, moist, of 4 or more and redox

depletions with chroma of 2 or less; or

(2) Hue of 10YR or redder and chroma of 2 or less;

or

(3) Hue of 2.5Y or yellower and chroma of 3 or less;

and

2. A mollic epipedon that has a texture finer than loamy

fine sand and that is either:

a. 40 cm or more thick in a frigid temperature regime; or

b. 50 cm or more thick.

Aquic Pachic Paleudolls

IHCD. Other Paleudolls that have a mollic epipedon that has a

texture finer than loamy fine sand and that is 50 cm or more thick.

Pachic Paleudolls

IHCE. Other Paleudolls that have, in one or more subhorizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Paleudolls

IHCF. Other Paleudolls that in normal years are saturated with

water in one or more layers within 100 cm of the mineral soil

surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Paleudolls

IHCG. Other Paleudolls that:

1. Have a calcic horizon that has its upper boundary within

100 cm of the mineral soil surface; and

2. In all parts above the calcic horizon, after the materials

between the soil surface and a depth of 18 cm have been

mixed, either are calcareous or have a texture of loamy fine

sand or coarser.

Calcic Paleudolls

IHCH. Other Paleudolls.

Typic Paleudolls

Vermudolls

Key to Subgroups

IHEA. Vermudolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Vermudolls

IHEB. Other Vermudolls that have a mollic epipedon less than

75 cm thick.

Haplic Vermudolls

IHEC. Other Vermudolls.

Typic Vermudolls
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Ustolls

Key to Great Groups

IGA. Ustolls that have a duripan that has its upper boundary

within 100 cm of the mineral soil surface.

Durustolls, p. 214

IGB. Other Ustolls that have a natric horizon.

Natrustolls, p. 220

IGC. Other Ustolls that:

1. Have either a calcic or gypsic horizon that has its upper

boundary within 100 cm of the mineral soil surface or a

petrocalcic horizon that has its upper boundary within 150

cm of the mineral soil surface; and

2. Do not have an argillic horizon above the calcic, gypsic,

or petrocalcic horizon; and

3. In all parts above the calcic, gypsic, or petrocalcic

horizon, after the materials between the soil surface and a

depth of 18 cm have been mixed, either are calcareous or

have a texture of loamy fine sand or coarser.

Calciustolls, p. 213

IGD. Other Ustolls that have either:

1. A petrocalcic horizon that has its upper boundary within

150 cm of the mineral soil surface; or

2. An argillic horizon that has one or both of the following:

a. With increasing depth, no clay decrease of 20 percent

or more (relative) from the maximum clay content

(noncarbonate clay) within 150 cm of the mineral soil

surface (and there is no densic, lithic, or paralithic contact

within that depth); and either

(1) Hue of 7.5YR or redder and chroma of 5 or more

in the matrix; or

(2) Common redox concentrations with hue

of 7.5YR or redder or chroma of 6 or more, or

both; or

b. 35 percent or more clay in its upper part and a clay

increase either of 20 percent or more (absolute) within a

vertical distance of 7.5 cm or of 15 percent or more

(absolute) within a vertical distance of 2.5 cm, in the fineearth fraction (and there is no densic, lithic, or paralithic

contact within 50 cm of the mineral soil surface).

Paleustolls, p. 222

IGE. Other Ustolls that have an argillic horizon.

Argiustolls, p. 209

IGF. Other Ustolls that have a mollic epipedon that:

1. Either below an Ap horizon or below a depth of 18 cm

from the mineral soil surface, contains 50 percent or more

(by volume) wormholes, wormcasts, or filled animal

burrows; and

2. Either rests on a lithic contact or has a transition zone to

the underlying horizon in which 25 percent or more of the

soil volume consists of discrete wormholes, wormcasts, or

animal burrows filled with material from the mollic epipedon

and from the underlying horizon.

Vermustolls, p. 224

IGG. Other Ustolls.

Haplustolls, p. 215

Argiustolls

Key to Subgroups

IGEA. Argiustolls that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. When neither irrigated nor fallowed to store moisture,

have one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some or all parts for six-tenths or more of the cumulative

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC.

Aridic Lithic Argiustolls

IGEB. Other Argiustolls that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. Above the argillic horizon, either an albic horizon or a
210 Keys to Soil Taxonomy

horizon that has color values too high for a mollic epipedon

and chroma too high for an albic horizon.

Alfic Lithic Argiustolls

IGEC. Other Argiustolls that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Argiustolls

IGED. Other Argiustolls that have both:

1. In one or more horizons within 100 cm of the mineral

soil surface, redox depletions with a chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage); and:

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Aquertic Argiustolls

IGEE. Other Argiustolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

have one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some or all parts for six-tenths or more of the cumulative

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 5 o

C; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC.

Torrertic Argiustolls

IGEF. Other Argiustolls that have all of the following:

1. A mollic epipedon that has a texture finer than loamy

fine sand and that is either:

a. 40 cm or more thick in a frigid temperature regime; or

b. 50 cm or more thick; and.

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

3. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic temperature regime and a

moisture control section that in normal years is dry in

some part for four-tenths or less of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 o

C; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC.

Pachic Udertic Argiustolls

IGEG. Other Argiustolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or
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wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for four-tenths or less of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC.

Udertic Argiustolls

IGEH. Other Argiustolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. A mollic epipedon that has a texture finer than loamy

fine sand and that is either:

a. 40 cm or more thick in a frigid temperature regime; or

b. 50 cm or more thick.

Pachic Vertic Argiustolls

IGEI. Other Argiustolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Argiustolls

IGEJ. Other Argiustolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Argiustolls

IGEK. Other Argiustolls that have both:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some or all parts for six-tenths or more of the cumulative

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1

/2 Fe, percent extracted by ammonium
212 Keys to Soil Taxonomy

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitritorrandic Argiustolls

IGEL. Other Argiustolls that have, throughout one or

more horizons with a total thickness of 18 cm or more

within 75 cm of the mineral soil surface, one or both of the

following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Argiustolls

IGEM. Other Argiustolls that have, in one or more horizons

within 100 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Argiustolls

IGEN. Other Argiustolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Argiustolls

IGEO. Other Argiustolls that have a mollic epipedon that has

a texture finer than loamy fine sand and that is either:

1. 40 cm or more thick in a frigid temperature regime; or

2. 50 cm or more thick.

Pachic Argiustolls

IGEP. Other Argiustolls that have either:

1. Above the argillic horizon, an albic horizon or a horizon

that has color values too high for a mollic epipedon and

chroma too high for an albic horizon; or

2. A glossic horizon, or interfingering of albic materials

into the upper part of the argillic horizon, or skeletans of

clean silt and sand covering 50 percent or more of the faces

of peds in the upper 5 cm of the argillic horizon.

Alfic Argiustolls

IGEQ. Other Argiustolls that have both:

1. A calcic horizon with its upper boundary within 100 cm

of the mineral soil surface; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Calcidic Argiustolls

IGER. Other Argiustolls that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

or all parts for six-tenths or more of the cumulative days per

year when the soil temperature at a depth of 50 cm below the

soil surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and
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b. Is dry in some or all parts for six-tenths or more of

the cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Argiustolls

IGES. Other Argiustolls that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for four-tenths or less of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC.

Udic Argiustolls

IGET. Other Argiustolls that have a brittle horizon that is

within 100 cm of the mineral soil surface, is 15 cm or more

thick, and has either some opal coatings or 20 percent or more

(by volume) durinodes.

Duric Argiustolls

IGEU. Other Argiustolls.

Typic Argiustolls

Calciustolls

Key to Subgroups

IGCA. Calciustolls that have a salic horizon that has its upper

boundary within 75 cm of the mineral soil surface.

Salidic Calciustolls

IGCB. Other Calciustolls that have a petrocalcic horizon and

a lithic contact within 50 cm of the mineral soil surface.

Lithic Petrocalcic Calciustolls

IGCC. Other Calciustolls that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Calciustolls

IGCD. Other Calciustolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some or all parts for six-tenths or more of the cumulative

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC.

Torrertic Calciustolls

IGCE. Other Calciustolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in
214 Keys to Soil Taxonomy

some part for four-tenths or less of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC.

Udertic Calciustolls

IGCF. Other Calciustolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Calciustolls

IGCG. Other Calciustolls that have a petrocalcic horizon that

has its upper boundary within 100 cm of the mineral soil

surface.

Petrocalcic Calciustolls

IGCH. Other Calciustolls that have a gypsic horizon with its

upper boundary within 100 cm of the mineral soil surface.

Gypsic Calciustolls

IGCI. Other Calciustolls that have, in one or more horizons

within 75 cm of the mineral soil surface, redox concentrations

and also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Calciustolls

IGCJ. Other Calciustolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Calciustolls

IGCK. Other Calciustolls that have a mollic epipedon that has

a texture finer than loamy fine sand and that is either:

1. 40 cm or more thick in a frigid temperature regime; or

2. 50 cm or more thick.

Pachic Calciustolls

IGCL. Other Calciustolls that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

or all parts for six-tenths or more of the cumulative days per

year when the soil temperature at a depth of 50 cm below the

soil surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some or all parts for six-tenths or more of

the cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Calciustolls

IGCM. Other Calciustolls that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

or all parts for four-tenths or less of the consecutive days per

year when the soil temperature at a depth of 50 cm below the

soil surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC.

Udic Calciustolls

IGCN. Other Calciustolls.

Typic Calciustolls

Durustolls

Key to Subgroups

IGAA. Durustolls that have a natric horizon above the

duripan.

Natric Durustolls

IGAB. Other Durustolls that:

1. Do not have an argillic horizon above the duripan; and
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2. Have an aridic moisture regime that borders on ustic.

Haploduridic Durustolls

IGAC. Other Durustolls that have an aridic moisture regime

that borders on ustic.

Argiduridic Durustolls

IGAD. Other Durustolls that do not have an argillic horizon

above the duripan.

Entic Durustolls

IGAE. Other Durustolls that have a duripan that is strongly

cemented or less cemented in all subhorizons.

Haplic Durustolls

IGAF. Other Durustolls.

Typic Durustolls

Haplustolls

Key to Subgroups

IGGA. Haplustolls that have a salic horizon that has its upper

boundary within 75 cm of the mineral soil surface.

Salidic Haplustolls

IGGB. Other Haplustolls that have, in part of each pedon, a

lithic contact within 50 cm of the mineral soil surface.

Ruptic-Lithic Haplustolls

IGGC. Other Haplustolls that have both:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid soil temperature regime and a moisture

control section that in normal years is dry in all parts for

four-tenths or more of the cumulative days per year when

the temperature at a depth of 50 cm below the soil surface

is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that, in 6 normal years, is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that, in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

8 o

C; and

(2) Is dry in some part for six-tenths or more of the

cumulative days per year when the temperature at a

depth of 50 cm below the soil surface is higher than

5 oC; and

2. A lithic contact within 50 cm of the mineral soil surface.

Aridic Lithic Haplustolls

IGGD. Other Haplustolls that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Haplustolls

IGGE. Other Haplustolls that have both:

1. In one or more horizons within 100 cm of the mineral

soil surface, redox depletions with a chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage); and:

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Aquertic Haplustolls

IGGF. Other Haplustolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in
216 Keys to Soil Taxonomy

some or all parts for six-tenths or more of the cumulative

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC.

Torrertic Haplustolls

IGGG. Other Haplustolls that have all of the following:

1. A mollic epipedon that has a texture finer than loamy

fine sand and that is either:

a. 40 cm or more thick in a frigid temperature regime; or

b. 50 cm or more thick.

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

3. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for four-tenths or less of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 o

C; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 o

C.

Pachic Udertic Haplustolls

IGGH. Other Haplustolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for four-tenths or less of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 o

C; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that

in normal years is dry in some or all parts for fewer than

120 cumulative days per year when the soil temperature

at a depth of 50 cm below the soil surface is higher than

8 oC.

Udertic Haplustolls

IGGI. Other Haplustolls that have both:

1. A mollic epipedon that has a texture finer than loamy

fine sand and that is either:

a. 40 cm or more thick in a frigid temperature regime; or

b. 50 cm or more thick; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Pachic Vertic Haplustolls

IGGJ. Other Haplustolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedge-
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shaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Haplustolls

IGGK. Other Haplustolls that have both:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years remains moist in some or all parts for fewer

than 90 consecutive days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 8 oC; and

2. An apparent CEC (by 1N NH4OAc pH 7) of less than 24

cmol(+)/kg clay in 50 percent or more of the soil volume

between a depth of 25 cm from the mineral soil surface and

either a depth of 100 cm or a densic, lithic, or paralithic

contact if shallower. (If the ratio of [percent water retained at

1500 kPa tension minus percent organic carbon] to the

percentage of measured clay is 0.6 or more, then the

percentage of clay is considered to equal either the measured

percentage of clay or three times [percent water retained at

1500 kPa tension minus percent organic carbon], whichever

value is higher, but no more than 100.)

Torroxic Haplustolls

IGGL. Other Haplustolls that have an apparent CEC (by

1N NH4OAc pH 7) of less than 24 cmol(+)/kg clay in 50 percent

or more of the soil volume between a depth of 25 cm from the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact if shallower. (If the ratio of [percent

water retained at 1500 kPa tension minus percent organic

carbon] to the percentage of measured clay is 0.6 or more, then

the percentage of clay is considered to equal either the measured

percentage of clay or three times [percent water retained at 1500

kPa tension minus percent organic carbon], whichever value is

higher, but no more than 100.)

Oxic Haplustolls

IGGM. Other Haplustolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haplustolls

IGGN. Other Haplustolls that have both:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitritorrandic Haplustolls

IGGO. Other Haplustolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:
218 Keys to Soil Taxonomy

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Haplustolls

IGGP. Other Haplustolls that have:

1. Either:

a. A frigid soil temperature regime and a mollic

epipedon 40 cm or more thick, of which less than 50

percent has a sandy or sandy-skeletal particle-size class,

and there is no densic or paralithic contact and no sandy

or sandy-skeletal particle-size class at a depth between 40

and 50 cm from the mineral soil surface; or

b. A mollic epipedon that is 50 cm or more thick and

has a texture finer than loamy fine sand; and

2. An irregular decrease in organic-carbon content from a

depth of 25 cm below the mineral soil surface to a depth of

125 cm or to a densic, lithic, or paralithic contact if

shallower; and

3. A slope of less than 25 percent; and

4. In one or more horizons within 100 cm of the mineral

soil surface, redox depletions with chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Cumulic Haplustolls

IGGQ. Other Haplustolls that have:

1. Either:

a. A frigid soil temperature regime and a mollic

epipedon 40 cm or more thick, of which less than 50

percent has a sandy or sandy-skeletal particle-size class,

and there is no densic or paralithic contact and no sandy

or sandy-skeletal particle-size class at a depth between 40

and 50 cm from the mineral soil surface; or

b. A mollic epipedon that is 50 cm or more thick and

has a texture finer than loamy fine sand; and

2. An irregular decrease in organic-carbon content from a

depth of 25 cm below the mineral soil surface to a depth of

125 cm or to a densic, lithic, or paralithic contact if

shallower; and

3. A slope of less than 25 percent.

Cumulic Haplustolls

IGGR. Other Haplustolls that have anthraquic conditions.

Anthraquic Haplustolls

IGGS. Other Haplustolls that have both:

1. In one or more horizons within 100 cm of the mineral

soil surface, redox depletions with chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage); and

2. A slope of less than 25 percent; and either

a. An organic-carbon content of 0.3 percent or more at a

depth of 125 cm below the mineral soil surface; or

b. An irregular decrease in organic-carbon content from

a depth of 25 cm to a depth of 125 cm or to a densic,

lithic, or paralithic contact if shallower.

Fluvaquentic Haplustolls

IGGT. Other Haplustolls that have, in one or more horizons

within 100 cm of the mineral soil surface, redox depletions

with chroma of 2 or less and also aquic conditions for some

time in most years (or artificial drainage).

Aquic Haplustolls

IGGU. Other Haplustolls that have a mollic epipedon that has

a texture finer than loamy fine sand and that is either:

1. 40 cm or more thick in a frigid temperature regime; or

2. 50 cm or more thick.

Pachic Haplustolls

IGGV. Other Haplustolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplustolls

IGGW. Other Haplustolls that have both:

1. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in
Mollisols 219

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some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC; and

2. A slope of less than 25 percent; and either

a. An organic-carbon content of 0.3 percent or more at a

depth of 125 cm below the mineral soil surface; or

b. An irregular decrease in organic-carbon content from

a depth of 25 cm to a depth of 125 cm or to a densic,

lithic, or paralithic contact if shallower.

Torrifluventic Haplustolls

IGGX. Other Haplustolls that:

1. When neither irrigated nor fallowed to store moisture,

have one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC; and

2. Either:

a. Do not have a cambic horizon and do not, in any part

of the mollic epipedon below 25 cm from the mineral soil

surface, meet all of the requirements for a cambic horizon

except color; or

b. Have free carbonates throughout the cambic horizon

or in all parts of the mollic epipedon below a depth of 25

cm from the mineral soil surface.

Torriorthentic Haplustolls

IGGY. Other Haplustolls that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some or all parts for six-tenths or more of

the cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than 5 oC.

Aridic Haplustolls

IGGZ. Other Haplustolls that have a slope of less than 25

percent; and either

1. An organic-carbon content of 0.3 percent or more at a

depth of 125 cm below the mineral soil surface; or

2. An irregular decrease in organic-carbon content from a

depth of 25 cm to a depth of 125 cm or to a densic, lithic, or

paralithic contact if shallower.

Fluventic Haplustolls

IGGZa. Other Haplustolls that have a brittle horizon that is

within 100 cm of the mineral soil surface, is 15 cm or more

thick, and has either some opal coatings or 20 percent or more

(by volume) durinodes.

Duric Haplustolls
220 Keys to Soil Taxonomy

IGGZb. Other Haplustolls that:

1. When neither irrigated nor fallowed to store moisture,

have either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for four-tenths or less of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 8 oC; and

2. Either do not have a cambic horizon and do not, in the

lower part of the mollic epipedon, meet the requirements for

a cambic horizon, except for the color requirements, or have

carbonates throughout either the cambic horizon or the lower

part of the mollic epipedon.

Udorthentic Haplustolls

IGGZc. Other Haplustolls that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for four-tenths or less of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

days per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 8 oC.

Udic Haplustolls

IGGZd. Other Haplustolls that either:

1. Do not have a cambic horizon and do not, in any part of

the mollic epipedon below 25 cm from the mineral soil

surface, meet all of the requirements for a cambic horizon

except color; or

2. Have free carbonates throughout the cambic horizon or

in all parts of the mollic epipedon below a depth of 25 cm

from the mineral soil surface.

Entic Haplustolls

IGGZe. Other Haplustolls.

Typic Haplustolls

Natrustolls

Key to Subgroups

IGBA. Natrustolls that have all of the following:

1. Visible crystals of gypsum and/or more soluble salts

within 40 cm of the mineral soil surface; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower;

3. When neither irrigated nor fallowed to store moisture,

have one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some or all parts for six-tenths or more of the cumulative

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC.

Leptic Torrertic Natrustolls

IGBB. Other Natrustolls that have both:

1. One or both of the following:
Mollisols 221

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a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

have one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some or all parts for six-tenths or more of the cumulative

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC.

Torrertic Natrustolls

IGBC. Other Natrustolls that have both of the following:

1. Visible crystals of gypsum and/or more soluble salts

within 40 cm of the mineral soil surface; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Leptic Vertic Natrustolls

IGBD. Other Natrustolls that have both:

1. A glossic horizon or interfingering of albic materials

into a natric horizon; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm or

a densic, lithic, or paralithic contact, whichever is

shallower.

Glossic Vertic Natrustolls

IGBE. Other Natrustolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Natrustolls

IGBF. Other Natrustolls that have both:

1. Visible crystals of gypsum or of more soluble salts, or

both, within 40 cm of the mineral soil surface; and

2. When neither irrigated nor fallowed to store moisture,

have one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for fourtenths or more of the cumulative days per year when the

soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some or all parts for six-tenths or more of the cumulative

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 5 o

C; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at
222 Keys to Soil Taxonomy

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC.

Aridic Leptic Natrustolls

IGBG. Other Natrustolls that have visible crystals of gypsum

or of more soluble salts, or both, within 40 cm of the mineral

soil surface.

Leptic Natrustolls

IGBH. Other Natrustolls that have, in one or more horizons at

a depth between 50 and 100 cm from the mineral soil surface,

aquic conditions for some time in normal years (or artificial

drainage) and one of the following:

1. 50 percent or more chroma of 1 or less and hue of 2.5Y

or yellower; or

2. 50 percent or more chroma of 2 or less and redox

concentrations; or

3. 50 percent or more chroma of 2 or less and also a higher

exchangeable sodium percentage (or sodium adsorption

ratio) between the mineral soil surface and a depth of 25 cm

than in the underlying horizon.

Aquic Natrustolls

IGBI. Other Natrustolls that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for four-tenths

or more of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some or all parts for six-tenths or more of

the cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than 5 oC.

Aridic Natrustolls

IGBJ. Other Natrustolls that have a horizon, 15 cm or more

thick within 100 cm of the mineral soil surface, that either has

20 percent or more (by volume) durinodes or is brittle and has a

firm rupture-resistance class when moist.

Duric Natrustolls

IGBK. Other Natrustolls that have a glossic horizon or

interfingering of albic materials into a natric horizon.

Glossic Natrustolls

IGBL. Other Natrustolls.

Typic Natrustolls

Paleustolls

Key to Subgroups

IGDA. Paleustolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for less than

four-tenths of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some or all parts for six-tenths or more of the cumulative

days per year when the soil temperature at a depth of 50

cm below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 o

C; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil
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temperature at a depth of 50 cm below the soil surface

is higher than 5 oC.

Torrertic Paleustolls

IGDB. Other Paleustolls that have both:

1. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is

shallower; and

2. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for four-tenths or less of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 o

C; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC.

Udertic Paleustolls

IGDC. Other Paleustolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Vertic Paleustolls

IGDD. Other Paleustolls that have, in one or more horizons

within 100 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Paleustolls

IGDE. Other Paleustolls that have a mollic epipedon that has

a texture finer than loamy fine sand and that is 50 cm or more

thick.

Pachic Paleustolls

IGDF. Other Paleustolls that have a petrocalcic horizon within

150 cm of the mineral soil surface.

Petrocalcic Paleustolls

IGDG. Other Paleustolls that:

1. Have a calcic horizon within one of the following

particle-size class (by weighted average in the particle-size

control section) and depth combinations:

a. Sandy or sandy-skeletal and within 100 cm of the

mineral soil surface; or

b. Clayey, clayey-skeletal, fine, or very-fine and within

50 cm of the mineral soil surface; or

c. Any other class and within 60 cm of the mineral soil

surface; and

2. When neither irrigated nor fallowed to store moisture,

have one of the following:

a. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for less than

four-tenths of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

b. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for six-tenths or more of the cumulative days

per year when the soil temperature at a depth of 50 cm

below the soil surface is higher than 5 oC; or

c. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

(1) Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than

8 oC; and

(2) Is dry in some or all parts for six-tenths or more

of the cumulative days per year when the soil

temperature at a depth of 50 cm below the soil surface

is higher than 5 oC.

Calcidic Paleustolls

IGDH. Other Paleustolls that, when neither irrigated nor

fallowed to store moisture, have one of the following:

1. A frigid temperature regime and a moisture control

section that in normal years is dry in all parts for less than

four-tenths of the cumulative days per year when the soil
224 Keys to Soil Taxonomy

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

2. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for six-tenths or more of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 oC; or

3. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some or all parts for six-tenths or more of

the cumulative days per year when the soil temperature at

a depth of 50 cm below the soil surface is higher than 5 oC.

Aridic Paleustolls

IGDI. Other Paleustolls that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for four-tenths or less of the cumulative days per year

when the soil temperature at a depth of 50 cm below the soil

surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 8 oC.

Udic Paleustolls

IGDJ. Other Paleustolls have a calcic horizon within one of

the following particle-size class (by weighted average in the

particle-size control section) and depth combinations:

1. Sandy or sandy-skeletal and within 100 cm of the

mineral soil surface; or

2. Clayey, clayey-skeletal, fine, or very-fine and within 50

cm of the mineral soil surface; or

3. Any other class and within 60 cm of the mineral soil

surface.

Calcic Paleustolls

IGDK. Other Paleustolls that are calcareous throughout after

the surface soil has been mixed to a depth of 18 cm.

Entic Paleustolls

IGDL. Other Paleustolls.

Typic Paleustolls

Vermustolls

Key to Subgroups

IGFA. Vermustolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Vermustolls

IGFB. Other Vermustolls that have, in one or more horizons

within 100 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Vermustolls

IGFC. Other Vermustolls that have a mollic epipedon 75 cm

or more thick.

Pachic Vermustolls

IGFD. Other Vermustolls that have a mollic epipedon less

than 50 cm thick.

Entic Vermustolls

IGFE. Other Vermustolls.

Typic Vermustolls

Xerolls

Key to Great Groups

IFA. Xerolls that have a duripan within 100 cm of the mineral

soil surface.

Durixerolls, p. 227

IFB. Other Xerolls that have a natric horizon.

Natrixerolls, p. 232

IFC. Other Xerolls that have either:

1. A petrocalcic horizon that has its upper boundary within

150 cm of the mineral soil surface; or

2. An argillic horizon that has one or both of the following:

a. With increasing depth, no clay decrease of 20 percent

or more (relative) from the maximum clay content

(noncarbonate clay) within 150 cm of the mineral soil

surface (and there is no densic, lithic, or paralithic contact

within that depth); and either

(1) Hue of 7.5YR or redder and chroma of 5 or more

in the matrix; or

(2) Common redox concentrations with hue

of 7.5YR or redder or chroma of 6 or more, or both;

or

b. A clayey or clayey-skeletal particle-size class in its
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upper part and, at its upper boundary, a clay increase

either of 20 percent or more (absolute) within a vertical

distance of 7.5 cm or of 15 percent or more (absolute)

within a vertical distance of 2.5 cm, in the fine-earth

fraction (and there is no densic, lithic, or paralithic

contact within 50 cm of the mineral soil surface).

Palexerolls, p. 232

IFD. Other Xerolls that:

1. Have a calcic or gypsic horizon that has its upper

boundary within 150 cm of the mineral soil surface; and

2. In all parts above the calcic or gypsic horizon, after the

surface soil has been mixed to a depth of 18 cm, either are

calcareous or have a texture of loamy fine sand or coarser.

Calcixerolls, p. 227

IFE. Other Xerolls that have an argillic horizon.

Argixerolls, p. 225

IFF. Other Xerolls.

Haploxerolls, p. 229

Argixerolls

Key to Subgroups

IFEA. Argixerolls that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. A base saturation (by sum of cations) of 75 percent or

less in one or more horizons between either the mineral soil

surface or an Ap horizon, whichever is deeper, and the lithic

contact.

Lithic Ultic Argixerolls

IFEB. Other Argixerolls that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Argixerolls

IFEC. Other Argixerolls that have both:

1. An aridic moisture regime; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm or

a densic, lithic, or paralithic contact, whichever is

shallower.

Torrertic Argixerolls

IFED. Other Argixerolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Argixerolls

IFEE. Other Argixerolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Argixerolls

IFEF. Other Argixerolls that have both:

1. An aridic moisture regime; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitritorrandic Argixerolls

IFEG. Other Argixerolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and
226 Keys to Soil Taxonomy

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Argixerolls

IFEH. Other Argixerolls that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A base saturation (by sum of cations) of 75 percent

or less in one or more horizons between either an Ap horizon

or a depth of 25 cm from the mineral soil surface, whichever

is deeper, and either a depth of 75 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Aquultic Argixerolls

IFEI. Other Argixerolls that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Argixerolls

IFEJ. Other Argixerolls that in normal years are saturated with

water in one or more layers within 100 cm of the mineral soil

surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Argixerolls

IFEK. Other Argixerolls that have either:

1. Above the argillic horizon, an albic horizon or a horizon

that has color values too high for a mollic epipedon and

chroma too high for an albic horizon; or

2. A glossic horizon, or interfingering of albic materials

into the upper part of the argillic horizon, or skeletans of

clean silt and sand covering 50 percent or more of the faces

of peds in the upper 5 cm of the argillic horizon.

Alfic Argixerolls

IFEL. Other Argixerolls that have both:

1. A calcic horizon or identifiable secondary carbonates

within one of the following particle-size class (by weighted

average in the particle-size control section) and depth

combinations:

a. Sandy or sandy-skeletal and within 150 cm of the

mineral soil surface; or

b. Clayey, clayey-skeletal, fine, or very-fine and within

90 cm of the mineral soil surface; or

c. Any other class and within 110 cm of the mineral soil

surface; and

2. A mollic epipedon that is 50 cm or more thick and has a

texture finer than loamy fine sand.

Calcic Pachic Argixerolls

IFEM. Other Argixerolls that have both:

1. A mollic epipedon that is 50 cm or more thick and has a

texture finer than loamy fine sand; and

2. A base saturation (by sum of cations) of 75 percent or

less in one or more horizons between either an Ap horizon or

a depth of 25 cm from the mineral soil surface, whichever is

deeper, and either a depth of 75 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Pachic Ultic Argixerolls

IFEN. Other Argixerolls that have a mollic epipedon that is 50

cm or more thick and has a texture finer than loamy fine sand.

Pachic Argixerolls

IFEO. Other Argixerolls that have both:

1. An aridic moisture regime; and

2. A horizon within 100 cm of the mineral soil surface that

is 15 cm or more thick and either has 20 percent or more (by

volume) durinodes or is brittle and has a firm ruptureresistance class when moist.

Argiduridic Argixerolls

IFEP. Other Argixerolls that have a horizon within 100 cm of

the mineral soil surface that is 15 cm or more thick and either

has 20 percent or more (by volume) durinodes or is brittle and

has a firm rupture-resistance class when moist.

Duric Argixerolls

IFEQ. Other Argixerolls that have both:

1. An aridic moisture regime; and

2. A calcic horizon or identifiable secondary carbonates

within one of the following particle-size class (by weighted

average in the particle-size control section) and depth

combinations:

a. Sandy or sandy-skeletal and within 150 cm of the

mineral soil surface; or

b. Clayey, clayey-skeletal, fine, or very-fine and within

90 cm of the mineral soil surface; or

c. Any other class and within 110 cm of the mineral soil

surface.

Calciargidic Argixerolls
Mollisols 227

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IFER. Other Argixerolls that have an aridic moisture regime.

Aridic Argixerolls

IFES. Other Argixerolls that have a calcic horizon or

identifiable secondary carbonates within one of the following

particle-size class (by weighted average in the particle-size

control section) and depth combinations:

1. Sandy or sandy-skeletal and within 150 cm of the

mineral soil surface; or

2. Clayey, clayey-skeletal, fine, or very-fine and within 90

cm of the mineral soil surface; or

3. Any other class and within 110 cm of the mineral soil

surface.

Calcic Argixerolls

IFET. Other Argixerolls that have a base saturation (by sum of

cations) of 75 percent or less in one or more horizons between

either an Ap horizon or a depth of 25 cm from the mineral soil

surface, whichever is deeper, and either a depth of 75 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Ultic Argixerolls

IFEU. Other Argixerolls.

Typic Argixerolls

Calcixerolls

Key to Subgroups

IFDA. Calcixerolls that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Calcixerolls

IFDB. Other Calcixerolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between

the mineral soil surface and either a depth of 100 cm

or a densic, lithic, or paralithic contact, whichever is

shallower.

Vertic Calcixerolls

IFDC. Other Calcixerolls that have, in one or more horizons

within 75 cm of the mineral soil surface, redox concentrations

and also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Calcixerolls

IFDD. Other Calcixerolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Calcixerolls

IFDE. Other Calcixerolls that have a mollic epipedon that is

50 cm or more thick and has a texture finer than loamy fine

sand.

Pachic Calcixerolls

IFDF. Other Calcixerolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter, of which 5 percent or

more is volcanic glass, and [(Al plus 1

/2 Fe, percent extracted

by ammonium oxalate) times 60] plus the volcanic glass

(percent) is equal to 30 or more.

Vitrandic Calcixerolls

IFDG. Other Calcixerolls that have an aridic moisture regime.

Aridic Calcixerolls

IFDH. Other Calcixerolls that have a mollic epipedon that

has, below any Ap horizon, 50 percent or more (by volume)

wormholes, wormcasts, or filled animal burrows.

Vermic Calcixerolls

IFDI. Other Calcixerolls.

Typic Calcixerolls

Durixerolls

Key to Subgroups

IFAA. Durixerolls that have, above the duripan, one or both

of the following:

1. Cracks that are 5 mm or more wide through a thickness

of 30 cm or more for some time in normal years and

slickensides or wedge-shaped aggregates in a layer 15 cm or

more thick; or

2. A linear extensibility of 6.0 cm or more.

Vertic Durixerolls

IFAB. Other Durixerolls that have both:

1. An aridic moisture regime; and
228 Keys to Soil Taxonomy

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitritorrandic Durixerolls

IFAC. Other Durixerolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Durixerolls

IFAD. Other Durixerolls that have, in one or more horizons

above the duripan, redox depletions with chroma of 2 or less

and also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Durixerolls

IFAE. Other Durixerolls that have:

1. An aridic moisture regime; and

2. An argillic horizon that, with increasing depth, has a

clay increase either of 20 percent or more (absolute) within a

vertical distance of 7.5 cm or of 15 percent or more

(absolute) within a vertical distance of 2.5 cm; and

3. A duripan that is neither very strongly cemented nor

indurated in any subhorizon.

Paleargidic Durixerolls

IFAF. Other Durixerolls that have both:

1. An aridic moisture regime; and

2. An argillic horizon that, with increasing depth, has a

clay increase either of 20 percent or more (absolute) within a

vertical distance of 7.5 cm or of 15 percent or more

(absolute) within a vertical distance of 2.5 cm.

Abruptic Argiduridic Durixerolls

IFAG. Other Durixerolls that:

1. Have an aridic moisture regime; and

2. Do not have an argillic horizon above the duripan; and

3. Have a duripan that is neither very strongly cemented

nor indurated in any subhorizon.

Cambidic Durixerolls

IFAH. Other Durixerolls that:

1. Have an aridic moisture regime; and

2. Do not have an argillic horizon above the duripan.

Haploduridic Durixerolls

IFAI. Other Durixerolls that have:

1. An aridic moisture regime; and

2. A duripan that is neither very strongly cemented nor

indurated in any subhorizon.

Argidic Durixerolls

IFAJ. Other Durixerolls that have an aridic moisture

regime.

Argiduridic Durixerolls

IFAK. Other Durixerolls that have both:

1. An argillic horizon that, with increasing depth, has a

clay increase either of 20 percent or more (absolute) within a

vertical distance of 7.5 cm or of 15 percent or more

(absolute) within a vertical distance of 2.5 cm; and

2. A duripan that is neither very strongly cemented nor

indurated in any subhorizon.

Haplic Palexerollic Durixerolls

IFAL. Other Durixerolls that have an argillic horizon that,

with increasing depth, has a clay increase either of 20 percent

or more (absolute) within a vertical distance of 7.5 cm or of

15 percent or more (absolute) within a vertical distance of 2.5

cm.

Palexerollic Durixerolls

IFAM. Other Durixerolls that:

1. Have a duripan that is neither very strongly cemented

nor indurated in any subhorizon; and

2. Do not have an argillic horizon above the duripan.

Haplic Haploxerollic Durixerolls
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IFAN. Other Durixerolls that do not have an argillic horizon

above the duripan.

Haploxerollic Durixerolls

IFAO. Other Durixerolls that have a duripan that is neither

very strongly cemented nor indurated in any subhorizon.

Haplic Durixerolls

IFAP. Other Durixerolls.

Typic Durixerolls

Haploxerolls

Key to Subgroups

IFFA. Haploxerolls that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. A base saturation (by sum of cations) of 75 percent or

less in one or more horizons between either the mineral soil

surface or an Ap horizon, whichever is deeper, and the lithic

contact.

Lithic Ultic Haploxerolls

IFFB. Other Haploxerolls that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Haploxerolls

IFFC. Other Haploxerolls that have both:

1. An aridic moisture regime; and

2. One or both of the following:

a. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick

that has its upper boundary within 125 cm of the mineral

soil surface; or

b. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a

densic, lithic, or paralithic contact, whichever is shallower.

Torrertic Haploxerolls

IFFD. Other Haploxerolls that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Haploxerolls

IFFE. Other Haploxerolls that have throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haploxerolls

IFFF. Other Haploxerolls that have both:

1. An aridic moisture regime; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or both of the following:

a. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

b. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitritorrandic Haploxerolls

IFFG. Other Haploxerolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Haploxerolls

IFFH. Other Haploxerolls that have:

1. A mollic epipedon that is 50 cm or more thick and has a

texture finer than loamy fine sand; and

2. An irregular decrease in organic-carbon content from a
230 Keys to Soil Taxonomy

depth of 25 cm below the mineral soil surface to a depth of

125 cm or to a densic, lithic, or paralithic contact if

shallower; and

3. A slope of less than 25 percent; and

4. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage).

Aquic Cumulic Haploxerolls

IFFI. Other Haploxerolls that have:

1. A mollic epipedon that is 50 cm or more thick and has a

texture finer than loamy fine sand; and

2. An irregular decrease in organic-carbon content from a

depth of 25 cm below the mineral soil surface to a depth of

125 cm or to a densic, lithic, or paralithic contact if

shallower; and

3. A slope of less than 25 percent; and

4. A base saturation (by sum of cations) of 75 percent or

less in one or more horizons between either an Ap horizon or

a depth of 25 cm from the mineral soil surface, whichever is

deeper, and either a depth of 75 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Cumulic Ultic Haploxerolls

IFFJ. Other Haploxerolls that have:

1. A mollic epipedon that is 50 cm or more thick and has a

texture finer than loamy fine sand; and

2. An irregular decrease in organic-carbon content from a

depth of 25 cm below the mineral soil surface to a depth of

125 cm or to a densic, lithic, or paralithic contact if

shallower; and

3. A slope of less than 25 percent.

Cumulic Haploxerolls

IFFK. Other Haploxerolls that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A slope of less than 25 percent; and either

a. An organic-carbon content of 0.3 percent or more

in all horizons within 125 cm of the mineral soil surface;

or

b. An irregular decrease in organic-carbon content from

a depth of 25 cm to a depth of 125 cm or to a densic,

lithic, or paralithic contact if shallower.

Fluvaquentic Haploxerolls

IFFL. Other Haploxerolls that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A horizon, 15 cm or more thick within 100 cm of the

mineral soil surface, that either has 20 percent or more (by

volume) durinodes or is brittle and has a firm ruptureresistance class when moist.

Aquic Duric Haploxerolls

IFFM. Other Haploxerolls that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A base saturation (by sum of cations) of 75 percent or

less in one or more horizons between either an Ap horizon or

a depth of 25 cm from the mineral soil surface, whichever is

deeper, and either a depth of 75 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Aquultic Haploxerolls

IFFN. Other Haploxerolls that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Haploxerolls

IFFO. Other Haploxerolls that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haploxerolls

IFFP. Other Haploxerolls that have both:

1. A mollic epipedon that is 50 cm or more thick and has a

texture finer than loamy fine sand; and

2. A calcic horizon or identifiable secondary carbonates

within one of the following particle-size class (by weighted

average in the particle-size control section) and depth

combinations:
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a. Sandy or sandy-skeletal and within 150 cm of the

mineral soil surface; or

b. Clayey, clayey-skeletal, fine, or very-fine and within

90 cm of the mineral soil surface; or

c. Any other class and within 110 cm of the mineral soil

surface.

Calcic Pachic Haploxerolls

IFFQ. Other Haploxerolls that have both:

1. A mollic epipedon that is 50 cm or more thick and has a

texture finer than loamy fine sand; and

2. A base saturation (by sum of cations) of 75 percent or

less in one or more horizons between either an Ap horizon or

a depth of 25 cm from the mineral soil surface, whichever is

deeper, and either a depth of 75 cm or a densic, lithic, or

paralithic contact, whichever is shallower.

Pachic Ultic Haploxerolls

IFFR. Other Haploxerolls that have a mollic epipedon that is

50 cm or more thick and has a texture finer than loamy fine

sand.

Pachic Haploxerolls

IFFS. Other Haploxerolls that have:

1. An aridic moisture regime; and

2. A slope of less than 25 percent; and either

a. An organic-carbon content of 0.3 percent or more

in all horizons within 125 cm of the mineral soil surface;

or

b. An irregular decrease in organic-carbon content from

a depth of 25 cm to a depth of 125 cm or to a densic,

lithic, or paralithic contact if shallower.

Torrifluventic Haploxerolls

IFFT. Other Haploxerolls that have both:

1. An aridic moisture regime; and

2. A horizon within 100 cm of the mineral soil surface that

is 15 cm or more thick and either has 20 percent or more (by

volume) durinodes or is brittle and has a firm ruptureresistance class when moist.

Duridic Haploxerolls

IFFU. Other Haploxerolls that have both:

1. An aridic moisture regime; and

2. A calcic horizon or identifiable secondary carbonates

within one of the following particle-size class (by weighted

average in the particle-size control section) and depth

combinations:

a. Sandy or sandy-skeletal and within 150 cm of the

mineral soil surface; or

b. Clayey, clayey-skeletal, fine, or very-fine and within

90 cm of the mineral soil surface; or

c. Any other class and within 110 cm of the mineral soil

surface.

Calcidic Haploxerolls

IFFV. Other Haploxerolls that have both:

1. An aridic moisture regime; and

2. A sandy particle-size class in all horizons within 100 cm

of the mineral soil surface.

Torripsammentic Haploxerolls

IFFW. Other Haploxerolls that:

1. Have an aridic moisture regime; and

2. Either:

a. Do not have a cambic horizon and do not, in any part

of the mollic epipedon below 25 cm from the mineral soil

surface, meet all of the requirements for a cambic horizon

except color; or

b. Have free carbonates throughout the cambic horizon

or in all parts of the mollic epipedon below a depth of 25

cm from the mineral soil surface.

Torriorthentic Haploxerolls

IFFX. Other Haploxerolls that have an aridic moisture regime.

Aridic Haploxerolls

IFFY. Other Haploxerolls that have a horizon within 100 cm

of the mineral soil surface that is 15 cm or more thick and either

has 20 percent or more (by volume) durinodes or is brittle and

has a firm rupture-resistance class when moist.

Duric Haploxerolls

IFFZ. Other Haploxerolls that have a sandy particle-size class

in all horizons within 100 cm of the mineral soil surface.

Psammentic Haploxerolls

IFFZa. Other Haploxerolls that have a slope of less than 25

percent; and either

1. An organic-carbon content of 0.3 percent or more in all

horizons within 125 cm of the mineral soil surface; or

2. An irregular decrease in organic-carbon content from a

depth of 25 cm to a depth of 125 cm or to a densic, lithic, or

paralithic contact if shallower.

Fluventic Haploxerolls

IFFZb. Other Haploxerolls that have a mollic epipedon that
232 Keys to Soil Taxonomy

has granular structure and that has, below any Ap horizon, 50

percent or more (by volume) wormholes, wormcasts, or filled

animal burrows.

Vermic Haploxerolls

IFFZc. Other Haploxerolls that have a calcic horizon or

identifiable secondary carbonates within one of the following

particle-size class (by weighted average in the particle-size

control section) and depth combinations:

1. Sandy or sandy-skeletal and within 150 cm of the

mineral soil surface; or

2. Clayey, clayey-skeletal, fine, or very-fine and within 90

cm of the mineral soil surface; or

3. Any other class and within 110 cm of the mineral soil

surface.

Calcic Haploxerolls

IFFZd. Other Haploxerolls that:

1. Do not have a cambic horizon and do not, in the lower

part of the mollic epipedon, meet all of the requirements for

a cambic horizon except color; and

2. Have a base saturation (by sum of cations) of

75 percent or less in one or more horizons between either

an Ap horizon or a depth of 25 cm from the mineral soil

surface, whichever is deeper, and either a depth of 75 cm or

a densic, lithic, or paralithic contact, whichever is shallower.

Entic Ultic Haploxerolls

IFFZe. Other Haploxerolls that have a base saturation (by sum

of cations) of 75 percent or less in one or more horizons

between either an Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and either a depth of

75 cm or a densic, lithic, or paralithic contact, whichever is

shallower.

Ultic Haploxerolls

IFFZf. Other Haploxerolls that either:

1. Do not have a cambic horizon and do not, in any part of

the mollic epipedon below 25 cm from the mineral soil

surface, meet all of the requirements for a cambic horizon

except color; or

2. Have free carbonates throughout the cambic horizon or

in all parts of the mollic epipedon below a depth of 25 cm

from the mineral soil surface.

Entic Haploxerolls

IFFZg. Other Haploxerolls.

Typic Haploxerolls

Natrixerolls

Key to Subgroups

IFBA. Natrixerolls that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Natrixerolls

IFBB. Other Natrixerolls that have both:

1. In one or more horizons within 75 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also

aquic conditions for some time in normal years (or artificial

drainage); and

2. A horizon, 15 cm or more thick within 100 cm of the

mineral soil surface, that either has 20 percent or more (by

volume) durinodes or is brittle and has a firm ruptureresistance class when moist.

Aquic Duric Natrixerolls

IFBC. Other Natrixerolls that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Natrixerolls

IFBD. Other Natrixerolls that have an aridic moisture regime.

Aridic Natrixerolls

IFBE. Other Natrixerolls that have a horizon within 100 cm of

the mineral soil surface that is 15 cm or more thick and either

has 20 percent or more (by volume) durinodes or is brittle and

has a firm rupture-resistance class when moist.

Duric Natrixerolls

IFBF. Other Natrixerolls.

Typic Natrixerolls

Palexerolls

Key to Subgroups

IFCA. Palexerolls that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that are
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5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Palexerolls

IFCB. Other Palexerolls that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or both of the following:

1. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

2. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1

/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Vitrandic Palexerolls

IFCC. Other Palexerolls that have, in one or more horizons

within 75 cm of the mineral soil surface, redox depletions with

chroma of 2 or less and also aquic conditions for some time in

normal years (or artificial drainage).

Aquic Palexerolls

IFCD. Other Palexerolls that have a mollic epipedon that is 50

cm or more thick and has a texture finer than loamy fine sand.

Pachic Palexerolls

IFCE. Other Palexerolls that have both:

1. An aridic moisture regime; and

2. A petrocalcic horizon that has its upper boundary within

150 cm of the mineral soil surface.

Petrocalcidic Palexerolls

IFCF. Other Palexerolls that have a horizon, 15 cm or more

thick within 100 cm of the mineral soil surface, that either has

20 percent or more (by volume) durinodes or is brittle and has a

firm rupture-resistance class when moist.

Duric Palexerolls

IFCG. Other Palexerolls that have an aridic moisture regime.

Aridic Palexerolls

IFCH. Other Palexerolls that have a petrocalcic horizon that

has its upper boundary within 150 cm of the mineral soil

surface.

Petrocalcic Palexerolls

IFCI. Other Palexerolls that have a base saturation of 75

percent or less in one or more subhorizons either within the

argillic horizon if more than 50 cm thick or within its upper 50

cm.

Ultic Palexerolls

IFCJ. Other Palexerolls that have an argillic horizon that has

either:

1. Less than 35 percent clay in the upper part; or

2. At its upper boundary, a clay increase that is both less

than 20 percent (absolute) within a vertical distance of 7.5

cm and less than 15 percent (absolute) within a vertical

distance of 2.5 cm, in the fine-earth fraction.

Haplic Palexerolls

IFCK. Other Palexerolls.

Typic Palexerolls

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Key to Suborders

EA. Oxisols that have aquic conditions for some time in

normal years (or artificial drainage) in one or more horizons

within 50 cm of the mineral soil surface and have one or more

of the following:

1. A histic epipedon; or

2. An epipedon with a color value, moist, of 3 or less

and, directly below it, a horizon with chroma of 2 or less;

or

3. Distinct or prominent redox concentrations within 50 cm

of the mineral soil surface, an epipedon, and, directly below

it, a horizon with one or both of the following:

a. 50 percent or more hue of 2.5Y or yellower; or

b. Chroma of 3 or less; or

4. Within 50 cm of the mineral soil surface, enough active

ferrous iron to give a positive reaction to alpha,alphadipyridyl at a time when the soil is not being irrigated.

Aquox, p. 235

EB. Other Oxisols that have an aridic moisture regime.

Torrox, p. 240

EC. Other Oxisols that have an ustic or xeric moisture regime.

Ustox, p. 245

ED. Other Oxisols that have a perudic moisture regime.

Perox, p. 236

EE. Other Oxisols.

Udox, p. 241

Aquox

Key to Great Groups

EAA. Aquox that have, in one or more subhorizons of an oxic

or kandic horizon within 150 cm of the mineral soil surface, an

apparent ECEC of less than 1.50 cmol(+) per kg clay and a pH

value (in 1N KCl) of 5.0 or more.

Acraquox, p. 235

EAB. Other Aquox that have plinthite forming a continuous

phase within 125 cm of the mineral soil surface.

Plinthaquox, p. 236

EAC. Other Aquox that have a base saturation (by NH4

OAc)

of 35 percent or more in all horizons within 125 cm of the

mineral soil surface.

Eutraquox, p. 235

EAD. Other Aquox.

Haplaquox, p. 236

Acraquox

Key to Subgroups

EAAA. Acraquox that have 5 percent or more (by volume)

plinthite in one or more horizons within 125 cm of the mineral

soil surface.

Plinthic Acraquox

EAAB. Other Acraquox that have, directly below an

epipedon, a horizon 10 cm or more thick that has 50 percent or

more chroma of 3 or more.

Aeric Acraquox

EAAC. Other Acraquox.

Typic Acraquox

Eutraquox

Key to Subgroups

EACA. Eutraquox that have a histic epipedon.

Histic Eutraquox

EACB. Other Eutraquox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Eutraquox

EACC. Other Eutraquox that have, directly below an

epipedon, a horizon 10 cm or more thick that has 50 percent or

more chroma of 3 or more.

Aeric Eutraquox

CHAPTER 13

Oxisols
236 Keys to Soil Taxonomy

EACD. Other Eutraquox that have 16 kg/m2 or more

organic carbon between the mineral soil surface and a depth

of 100 cm.

Humic Eutraquox

EACE. Other Eutraquox.

Typic Eutraquox

Haplaquox

Key to Subgroups

EADA. Haplaquox that have a histic epipedon.

Histic Haplaquox

EADB. Other Haplaquox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Haplaquox

EADC. Other Haplaquox that have, directly below an

epipedon, a horizon 10 cm or more thick that has 50 percent or

more chroma of 3 or more.

Aeric Haplaquox

EADD. Other Haplaquox that have 16 kg/m2

 or more

organic carbon between the mineral soil surface and a depth

of 100 cm.

Humic Haplaquox

EADE. Other Haplaquox.

Typic Haplaquox

Plinthaquox

Key to Subgroups

EABA. Plintaquox that have, directly below an epipedon, a

horizon 10 cm or more thick that has 50 percent or more

chroma of 3 or more.

Aeric Plinthaquox

EABB. Other Plinthaquox.

Typic Plinthaquox

Perox

Key to Great Groups

EDA. Perox that have a sombric horizon within 150 cm of the

mineral soil surface.

Sombriperox, p. 240

EDB. Other Perox that have, in one or more subhorizons of an

oxic or kandic horizon within 150 cm of the mineral soil

surface, an apparent ECEC of less than 1.50 cmol(+) per kg

clay and a pH value (1N KCl) of 5.0 or more.

Acroperox, p. 236

EDC. Other Perox that have a base saturation (by NH4

OAc)

of 35 percent or more in all horizons within 125 cm of the

mineral soil surface.

Eutroperox, p. 237

EDD. Other Perox that have a kandic horizon that has its

upper boundary within 150 cm of the mineral soil surface.

Kandiperox, p. 239

EDE. Other Perox.

Haploperox, p. 238

Acroperox

Key to Subgroups

EDBA. Acroperox that have, within 125 cm of the mineral

soil surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Acroperox

EDBB. Other Acroperox that have a petroferric contact within

125 cm of the mineral soil surface.

Petroferric Acroperox

EDBC. Other Acroperox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Acroperox

EDBD. Other Acroperox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Acroperox

EDBE. Other Acroperox that have a delta pH (KCl pH

minus 1:1 water pH) with a 0 or net positive charge in a

layer 18 cm or more thick within 125 cm of the mineral soil

surface.

Anionic Acroperox

EDBF. Other Acroperox that have 5 percent or more (by
Oxisols 237

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volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Acroperox

EDBG. Other Acroperox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Acroperox

EDBH. Other Acroperox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Acroperox

EDBI. Other Acroperox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Acroperox

EDBJ. Other Acroperox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100 cm.

Humic Acroperox

EDBK. Other Acroperox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Acroperox

EDBL. Other Acroperox that have 50 percent or more hue

of 7.5YR or yellower and a color value, moist, of 6 or more

at a depth between 25 and 125 cm from the mineral soil

surface.

Xanthic Acroperox

EDBM. Other Acroperox.

Typic Acroperox

Eutroperox

Key to Subgroups

EDCA. Eutroperox that have, within 125 cm of the mineral

soil surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Eutroperox

EDCB. Other Eutroperox that have a petroferric contact

within 125 cm of the mineral soil surface.

Petroferric Eutroperox

EDCC. Other Eutroperox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Eutroperox

EDCD. Other Eutroperox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Eutroperox

EDCE. Other Eutroperox that have, in one or more horizons

within 125 cm of the mineral soil surface, both:

1. 5 percent or more (by volume) plinthite; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Plinthaquic Eutroperox

EDCF. Other Eutroperox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Eutroperox

EDCG. Other Eutroperox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Eutroperox

EDCH. Other Eutroperox that have a kandic horizon that
238 Keys to Soil Taxonomy

has its upper boundary within 150 cm of the mineral soil

surface.

Kandiudalfic Eutroperox

EDCI. Other Eutroperox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. An oxic horizon that has its lower boundary within 125

cm of the mineral soil surface.

Humic Inceptic Eutroperox

EDCJ. Other Eutroperox that have an oxic horizon that has its

lower boundary within 125 cm of the mineral soil surface.

Inceptic Eutroperox

EDCK. Other Eutroperox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Eutroperox

EDCL. Other Eutroperox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Eutroperox

EDCM. Other Eutroperox that have 16 kg/m2

 or more

organic carbon between the mineral soil surface and a depth

of 100 cm.

Humic Eutroperox

EDCN. Other Eutroperox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Eutroperox

EDCO. Other Eutroperox that have 50 percent or more hue of

7.5YR or yellower and a color value, moist, of 6 or more at a

depth between 25 and 125 cm from the mineral soil surface.

Xanthic Eutroperox

EDCP. Other Eutroperox.

Typic Eutroperox

Haploperox

Key to Subgroups

EDEA. Haploperox that have, within 125 cm of the mineral

soil surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Haploperox

EDEB. Other Haploperox that have a petroferric contact

within 125 cm of the mineral soil surface.

Petroferric Haploperox

EDEC. Other Haploperox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Haploperox

EDED. Other Haploperox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Haploperox

EDEE. Other Haploperox that have, in one or more horizons

within 125 cm of the mineral soil surface, both:

1. 5 percent or more (by volume) plinthite; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Plinthaquic Haploperox

EDEF. Other Haploperox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Haploperox

EDEG. Other Haploperox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Haploperox

EDEH. Other Haploperox that have, throughout one or more
Oxisols 239

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horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haploperox

EDEI. Other Haploperox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Haploperox

EDEJ. Other Haploperox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Haploperox

EDEK. Other Haploperox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100 cm.

Humic Haploperox

EDEL. Other Haploperox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Haploperox

EDEM. Other Haploperox that have 50 percent or more hue

of 7.5YR or yellower and a color value, moist, of 6 or more at a

depth between 25 and 125 cm from the mineral soil surface.

Xanthic Haploperox

EDEN. Other Haploperox.

Typic Haploperox

Kandiperox

Key to Subgroups

EDDA. Kandiperox that have, within 125 cm of the mineral

soil surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Kandiperox

EDDB. Other Kandiperox that have a petroferric contact

within 125 cm of the mineral soil surface.

Petroferric Kandiperox

EDDC. Other Kandiperox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Kandiperox

EDDD. Other Kandiperox that have a lithic contact within

125 cm of the mineral soil surface.

Lithic Kandiperox

EDDE. Other Kandiperox that have, in one or more horizons

within 125 cm of the mineral soil surface, both:

1. 5 percent or more (by volume) plinthite; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Plinthaquic Kandiperox

EDDF. Other Kandiperox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Kandiperox

EDDG. Other Kandiperox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Kandiperox

EDDH. Other Kandiperox that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Kandiperox

EDDI. Other Kandiperox that have both:
240 Keys to Soil Taxonomy

1. 16 kg/m2 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Kandiperox

EDDJ. Other Kandiperox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Kandiperox

EDDK. Other Kandiperox that have 16 kg/m2

 or more

organic carbon between the mineral soil surface and a depth

of 100 cm.

Humic Kandiperox

EDDL. Other Kandiperox that have, in all horizons

at a depth between 25 and 125 cm from the mineral soil surface,

more than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Kandiperox

EDDM. Other Kandiperox that have 50 percent or more

hue of 7.5YR or yellower and a color value, moist, of 6 or more

at a depth between 25 and 125 cm from the mineral soil surface.

Xanthic Kandiperox

EDDN. Other Kandiperox.

Typic Kandiperox

Sombriperox

Key to Subgroups

EDAA. Sombriperox that have a petroferric contact within

125 cm of the mineral soil surface.

Petroferric Sombriperox

EDAB. Other Sombriperox that have a lithic contact within

125 cm of the mineral soil surface.

Lithic Sombriperox

EDAC. Other Sombriperox that have 16 kg/m2

 or more

organic carbon between the mineral soil surface and a depth of

100 cm.

Humic Sombriperox

EDAD. Other Sombriperox.

Typic Sombriperox

Torrox

Key to Great Groups

EBA. Torrox that have, in one or more subhorizons of an oxic

or kandic horizon within 150 cm of the mineral soil surface, an

apparent ECEC of less than 1.50 cmol(+) per kg clay and a pH

value (1N KCl) of 5.0 or more.

Acrotorrox, p. 240

EBB. Other Torrox that have a base saturation (by NH4

OAc)

of 35 percent or more in all horizons within 125 cm of the

mineral soil surface.

Eutrotorrox, p. 240

EBC. Other Torrox.

Haplotorrox, p. 241

Acrotorrox

Key to Subgroups

EBAA. Acrotorrox that have a petroferric contact within 125

cm of the mineral soil surface.

Petroferric Acrotorrox

EBAB. Other Acrotorrox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Acrotorrox

EBAC. Other Acrotorrox.

Typic Acrotorrox

Eutrotorrox

Key to Subgroups

EBBA. Eutrotorrox that have a petroferric contact within 125

cm of the mineral soil surface.

Petroferric Eutrotorrox

EBBB. Other Eutrotorrox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Eutrotorrox

EBBC. Other Eutrotorrox.

Typic Eutrotorrox
Oxisols 241

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Haplotorrox

Key to Subgroups

EBCA. Haplotorrox that have a petroferric contact within 125

cm of the mineral soil surface.

Petroferric Haplotorrox

EBCB. Other Haplotorrox that have a lithic contact within

125 cm of the mineral soil surface.

Lithic Haplotorrox

EBCC. Other Haplotorrox.

Typic Haplotorrox

Udox

Key to Great Groups

EEA. Udox that have a sombric horizon within 150 cm of the

mineral soil surface.

Sombriudox, p. 245

EEB. Other Udox that have, in one or more subhorizons of an

oxic or kandic horizon within 150 cm of the mineral soil

surface, an apparent ECEC of less than 1.50 cmol(+) per kg

clay and a pH value (1N KCl) of 5.0 or more.

Acrudox, p. 241

EEC. Other Udox that have a base saturation (by NH4

OAc) of

35 percent or more in all horizons within 125 cm of the mineral

soil surface.

Eutrudox, p. 242

EED. Other Udox that have a kandic horizon that has its

upper boundary within 150 cm of the mineral soil surface.

Kandiudox, p. 244

EEE. Other Udox.

Hapludox, p. 243

Acrudox

Key to Subgroups

EEBA. Acrudox that have, within 125 cm of the mineral soil

surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Acrudox

EEBB. Other Acrudox that have a petroferric contact within

125 cm of the mineral soil surface.

Petroferric Acrudox

EEBC. Other Acrudox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Acrudox

EEBD. Other Acrudox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Acrudox

EEBE. Other Acrudox that have, within 125 cm of the mineral

soil surface, both:

1. A delta pH (KCl pH minus 1:1 water pH) with

a 0 or net positive charge in a layer 18 cm or more thick; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Anionic Aquic Acrudox

EEBF. Other Acrudox that have a delta pH (KCl pH minus

1:1 water pH) with a 0 or net positive charge in a layer 18 cm or

more thick within 125 cm of the mineral soil surface.

Anionic Acrudox

EEBG. Other Acrudox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Acrudox

EEBH. Other Acrudox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Acrudox

EEBI. Other Acrudox that have a base saturation (by

NH4

OAc) of 35 percent or more in all horizons within 125 cm

of the mineral soil surface.

Eutric Acrudox

EEBJ. Other Acrudox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and
242 Keys to Soil Taxonomy

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Acrudox

EEBK. Other Acrudox that have both:

1. 16 kg/m2 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Acrudox

EEBL. Other Acrudox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100 cm.

Humic Acrudox

EEBM. Other Acrudox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Acrudox

EEBN. Other Acrudox that have 50 percent or more hue

of 7.5YR or yellower and a color value, moist, of 6 or more

at a depth between 25 and 125 cm from the mineral soil surface.

Xanthic Acrudox

EEBO. Other Acrudox.

Typic Acrudox

Eutrudox

Key to Subgroups

EECA. Eutrudox that have, within 125 cm of the mineral soil

surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Eutrudox

EECB. Other Eutrudox that have a petroferric contact within

125 cm of the mineral soil surface.

Petroferric Eutrudox

EECC. Other Eutrudox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Eutrudox

EECD. Other Eutrudox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Eutrudox

EECE. Other Eutrudox that have, in one or more horizons

within 125 cm of the mineral soil surface, both:

1. 5 percent or more (by volume) plinthite; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Plinthaquic Eutrudox

EECF. Other Eutrudox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Eutrudox

EECG. Other Eutrudox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Eutrudox

EECH. Other Eutrudox that have a kandic horizon that has its

upper boundary within 150 cm of the mineral soil surface.

Kandiudalfic Eutrudox

EECI. Other Eutrudox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. An oxic horizon that has its lower boundary within 125

cm of the mineral soil surface.

Humic Inceptic Eutrudox

EECJ. Other Eutrudox that have an oxic horizon that has its

lower boundary within 125 cm of the mineral soil surface.

Inceptic Eutrudox

EECK. Other Eutrudox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and
Oxisols 243

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2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Eutrudox

EECL. Other Eutrudox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Eutrudox

EECM. Other Eutrudox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100 cm.

Humic Eutrudox

EECN. Other Eutrudox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Eutrudox

EECO. Other Eutrudox that have 50 percent or more hue of

7.5YR or yellower and a color value, moist, of 6 or more at a

depth between 25 and 125 cm from the mineral soil surface.

Xanthic Eutrudox

EECP. Other Eutrudox.

Typic Eutrudox

Hapludox

Key to Subgroups

EEEA. Hapludox that have, within 125 cm of the mineral soil

surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Hapludox

EEEB. Other Hapludox that have a petroferric contact within

125 cm of the mineral soil surface.

Petroferric Hapludox

EEEC. Other Hapludox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Hapludox

EEED. Other Hapludox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Hapludox

EEEE. Other Hapludox that have, in one or more horizons

within 125 cm of the mineral soil surface, both:

1. 5 percent or more (by volume) plinthite; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Plinthaquic Hapludox

EEEF. Other Hapludox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Hapludox

EEEG. Other Hapludox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Hapludox

EEEH. Other Hapludox that have an oxic horizon that has its

lower boundary within 125 cm of the mineral soil surface.

Inceptic Hapludox

EEEI. Other Hapludox that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Hapludox

EEEJ. Other Hapludox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:
244 Keys to Soil Taxonomy

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Hapludox

EEEK. Other Hapludox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Hapludox

EEEL. Other Hapludox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100 cm.

Humic Hapludox

EEEM. Other Hapludox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Hapludox

EEEN. Other Hapludox that have 50 percent or more hue of

7.5YR or yellower and a color value, moist, of 6 or more at a

depth between 25 and 125 cm from the mineral soil surface.

Xanthic Hapludox

EEEO. Other Hapludox.

Typic Hapludox

Kandiudox

Key to Subgroups

EEDA. Kandiudox that have, within 125 cm of the mineral

soil surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Kandiudox

EEDB. Other Kandiudox that have a petroferric contact

within 125 cm of the mineral soil surface.

Petroferric Kandiudox

EEDC. Other Kandiudox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Kandiudox

EEDD. Other Kandiudox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Kandiudox

EEDE. Other Kandiudox that have, in one or more horizons

within 125 cm of the mineral soil surface, both:

1. 5 percent or more (by volume) plinthite; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Plinthaquic Kandiudox

EEDF. Other Kandiudox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Kandiudox

EEDG. Other Kandiudox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Kandiudox

EEDH. Other Kandiudox that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Kandiudox

EEDI. Other Kandiudox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Kandiudox

EEDJ. Other Kandiudox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and
Oxisols 245

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2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Kandiudox

EEDK. Other Kandiudox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100 cm.

Humic Kandiudox

EEDL. Other Kandiudox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Kandiudox

EEDM. Other Kandiudox that have 50 percent or more hue of

7.5YR or yellower and a color value, moist, of 6 or more at a

depth between 25 and 125 cm from the mineral soil surface.

Xanthic Kandiudox

EEDN. Other Kandiudox.

Typic Kandiudox

Sombriudox

Key to Subgroups

EEAA. Sombriudox that have a petroferric contact within 125

cm of the mineral soil surface.

Petroferric Sombriudox

EEAB. Other Sombriudox that have a lithic contact within

125 cm of the mineral soil surface.

Lithic Sombriudox

EEAC. Other Sombriudox that have 16 kg/m2

 or more

organic carbon between the mineral soil surface and a depth

of 100 cm.

Humic Sombriudox

EEAD. Other Sombriudox.

Typic Sombriudox

Ustox

Key to Great Groups

ECA. Ustox that have a sombric horizon within 150 cm of the

mineral soil surface.

Sombriustox, p. 249

ECB. Other Ustox that have, in one or more subhorizons of an

oxic or kandic horizon within 150 cm of the mineral soil

surface, an apparent ECEC of less than 1.50 cmol(+) per kg

clay and a pH value (1N KCl) of 5.0 or more.

Acrustox, p. 245

ECC. Other Ustox that have a base saturation (by NH4

OAc) of

35 percent or more in all horizons within 125 cm of the mineral

soil surface.

Eutrustox, p. 246

ECD. Other Ustox that have a kandic horizon that has its

upper boundary within 150 cm of the mineral soil surface.

Kandiustox, p. 248

ECE. Other Ustox.

Haplustox, p. 247

Acrustox

Key to Subgroups

ECBA. Acrustox that have, within 125 cm of the mineral soil

surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Acrustox

ECBB. Other Acrustox that have a petroferric contact within

125 cm of the mineral soil surface.

Petroferric Acrustox

ECBC. Other Acrustox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Acrustox

ECBD. Other Acrustox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Acrustox

ECBE. Other Acrustox that have, within 125 cm of the

mineral soil surface, both:

1. A delta pH (KCl pH minus 1:1 water pH) with a 0 or net

positive charge in a layer 18 cm or more thick; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Anionic Aquic Acrustox
246 Keys to Soil Taxonomy

ECBF. Other Acrustox that have a delta pH (KCl pH minus

1:1 water pH) with a 0 or net positive charge in a layer 18 cm or

more thick within 125 cm of the mineral soil surface.

Anionic Acrustox

ECBG. Other Acrustox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Acrustox

ECBH. Other Acrustox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Acrustox

ECBI. Other Acrustox that have a base saturation (by

NH4

OAc) of 35 percent or more in all horizons within 125 cm

of the mineral soil surface.

Eutric Acrustox

ECBJ. Other Acrustox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Acrustox

ECBK. Other Acrustox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Acrustox

ECBL. Other Acrustox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100 cm.

Humic Acrustox

ECBM. Other Acrustox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Acrustox

ECBN. Other Acrustox that have 50 percent or more hue

of 7.5YR or yellower and a color value, moist, of 6 or more

at a depth between 25 and 125 cm from the mineral soil

surface.

Xanthic Acrustox

ECBO. Other Acrustox.

Typic Acrustox

Eutrustox

Key to Subgroups

ECCA. Eutrustox that have, within 125 cm of the mineral

soil surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less and also aquic conditions

for some time in normal years (or artificial drainage).

Aquic Petroferric Eutrustox

ECCB. Other Eutrustox that have a petroferric contact

within 125 cm of the mineral soil surface.

Petroferric Eutrustox

ECCC. Other Eutrustox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less and also aquic conditions

for some time in normal years (or artificial drainage).

Aquic Lithic Eutrustox

ECCD. Other Eutrustox that have a lithic contact within

125 cm of the mineral soil surface.

Lithic Eutrustox

ECCE. Other Eutrustox that have, in one or more horizons

within 125 cm of the mineral soil surface, both:

1. 5 percent or more (by volume) plinthite; and

2. Redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less and also aquic conditions

for some time in normal years (or artificial drainage).

Plinthaquic Eutrustox

ECCF. Other Eutrustox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of

the mineral soil surface.

Plinthic Eutrustox

ECCG. Other Eutrustox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions
Oxisols 247

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with a color value, moist, of 4 or more and chroma of 2 or less

and also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Eutrustox

ECCH. Other Eutrustox that have a kandic horizon that has its

upper boundary within 150 cm of the mineral soil surface.

Kandiustalfic Eutrustox

ECCI. Other Eutrustox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. An oxic horizon that has its lower boundary within 125

cm of the mineral soil surface.

Humic Inceptic Eutrustox

ECCJ. Other Eutrustox that have an oxic horizon that has its

lower boundary within 125 cm of the mineral soil surface.

Inceptic Eutrustox

ECCK. Other Eutrustox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Eutrustox

ECCL. Other Eutrustox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Eutrustox

ECCM. Other Eutrustox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100

cm.

Humic Eutrustox

ECCN. Other Eutrustox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Eutrustox

ECCO. Other Eutrustox that have 50 percent or more hue of

7.5YR or yellower and a color value, moist, of 6 or more at a

depth between 25 and 125 cm from the mineral soil surface.

Xanthic Eutrustox

ECCP. Other Eutrustox.

Typic Eutrustox

Haplustox

Key to Subgroups

ECEA. Haplustox that have, within 125 cm of the mineral soil

surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Haplustox

ECEB. Other Haplustox that have a petroferric contact within

125 cm of the mineral soil surface.

Petroferric Haplustox

ECEC. Other Haplustox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Haplustox

ECED. Other Haplustox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Haplustox

ECEE. Other Haplustox that have, in one or more horizons

within 125 cm of the mineral soil surface, both:

1. 5 percent or more (by volume) plinthite; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Plinthaquic Haplustox

ECEF. Other Haplustox that have 5 percent or more (by

volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Haplustox

ECEG. Other Haplustox that have, within 125 cm of the

mineral soil surface, both:
248 Keys to Soil Taxonomy

1. The lower boundary of the oxic horizon; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aqueptic Haplustox

ECEH. Other Haplustox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Haplustox

ECEI. Other Haplustox that are saturated with water in one or

more layers within 100 cm of the mineral soil surface in normal

years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplustox

ECEJ. Other Haplustox that have an oxic horizon that has

its lower boundary within 125 cm of the mineral soil surface.

Inceptic Haplustox

ECEK. Other Haplustox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Haplustox

ECEL. Other Haplustox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Haplustox

ECEM. Other Haplustox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100 cm.

Humic Haplustox

ECEN. Other Haplustox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Haplustox

ECEO. Other Haplustox that have 50 percent or more hue

of 7.5YR or yellower and a color value, moist, of 6 or more

at a depth between 25 and 125 cm from the mineral soil

surface.

Xanthic Haplustox

ECEP. Other Haplustox.

Typic Haplustox

Kandiustox

Key to Subgroups

ECDA. Kandiustox that have, within 125 cm of the mineral

soil surface, both:

1. A petroferric contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Petroferric Kandiustox

ECDB. Other Kandiustox that have a petroferric contact

within 125 cm of the mineral soil surface.

Petroferric Kandiustox

ECDC. Other Kandiustox that have, within 125 cm of the

mineral soil surface, both:

1. A lithic contact; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Lithic Kandiustox

ECDD. Other Kandiustox that have a lithic contact within 125

cm of the mineral soil surface.

Lithic Kandiustox

ECDE. Other Kandiustox that have, in one or more horizons

within 125 cm of the mineral soil surface, both:

1. 5 percent or more (by volume) plinthite; and

2. Redox depletions with a color value, moist, of 4 or more

and chroma of 2 or less and also aquic conditions for some

time in normal years (or artificial drainage).

Plinthaquic Kandiustox

ECDF. Other Kandiustox that have 5 percent or more (by
Oxisols 249

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volume) plinthite in one or more horizons within 125 cm of the

mineral soil surface.

Plinthic Kandiustox

ECDG. Other Kandiustox that have, in one or more horizons

within 125 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Kandiustox

ECDH. Other Kandiustox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. In all horizons at a depth between 25 and 125 cm from

the mineral soil surface, more than 50 percent colors that

have both of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less.

Humic Rhodic Kandiustox

ECDI. Other Kandiustox that have both:

1. 16 kg/m2

 or more organic carbon between the mineral

soil surface and a depth of 100 cm; and

2. 50 percent or more hue of 7.5YR or yellower and a

color value, moist, of 6 or more at a depth between 25 and

125 cm from the mineral soil surface.

Humic Xanthic Kandiustox

ECDJ. Other Kandiustox that have 16 kg/m2

 or more organic

carbon between the mineral soil surface and a depth of 100 cm.

Humic Kandiustox

ECDK. Other Kandiustox that have, in all horizons at a depth

between 25 and 125 cm from the mineral soil surface, more

than 50 percent colors that have both of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less.

Rhodic Kandiustox

ECDL. Other Kandiustox that have 50 percent or more hue of

7.5YR or yellower and a color value, moist, of 6 or more at a

depth between 25 and 125 cm from the mineral soil surface.

Xanthic Kandiustox

ECDM. Other Kandiustox.

Typic Kandiustox

Sombriustox

Key to Subgroups

ECAA. Sombriustox that have a petroferric contact within

125 cm of the mineral soil surface.

Petroferric Sombriustox

ECAB. Other Sombriustox that have a lithic contact within

125 cm of the mineral soil surface.

Lithic Sombriustox

ECAC. Other Sombriustox that have 16 kg/m2

 or more

organic carbon between the mineral soil surface and a depth of

100 cm.

Humic Sombriustox

ECAD. Other Sombriustox.

Typic Sombriustox

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Key to Suborders

CA. Spodosols that have aquic conditions for some time in

normal years (or artificial drainage) in one or more horizons

within 50 cm of the mineral soil surface and have one or both

of the following:

1. A histic epipedon; or

2. Within 50 cm of the mineral soil surface, redoximorphic

features in an albic or a spodic horizon.

Aquods, p. 251

CB. Other Spodosols that have, in normal years, a mean

annual soil temperature of 0 o

C or colder and a mean summer

soil temperature that:

1. Is 8 oC or colder if there is no O horizon; or

2. Is 5 oC or colder if there is an O horizon.

Gelods, p. 255

CC. Other Spodosols that have a cryic soil temperature

regime.

Cryods, p. 253

CD. Other Spodosols that have 6.0 percent or more organic

carbon in a layer 10 cm or more thick within the spodic

horizon.

Humods, p. 256

CE. Other Spodosols.

Orthods, p. 256

Aquods

Key to Great Groups

CAA. Aquods that have a cryic soil temperature regime.

Cryaquods, p. 252

CAB. Other Aquods that have less than 0.10 percent iron (by

ammonium oxalate) in 75 percent or more of the spodic

horizon.

Alaquods, p. 251

CAC. Other Aquods that have a fragipan with its upper

boundary within 100 cm of the mineral soil surface.

Fragiaquods, p. 253

CAD. Other Aquods that have a placic horizon within 100

cm of the mineral soil surface in 50 percent or more of each

pedon.

Placaquods, p. 253

CAE. Other Aquods that have, in 90 percent or more of each

pedon, a cemented soil layer that has its upper boundary within

100 cm of the mineral soil surface.

Duraquods, p. 252

CAF. Other Aquods that have episaturation.

Epiaquods, p. 253

CAG. Other Aquods.

Endoaquods, p. 252

Alaquods

Key to Subgroups

CABA. Alaquods that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Alaquods

CABB. Other Alaquods that have, in 90 percent or more of

each pedon, a cemented soil layer that does not slake in water

after air drying and has its upper boundary within 100 cm of the

mineral soil surface.

Duric Alaquods

CABC. Other Alaquods that have a histic epipedon.

Histic Alaquods

CABD. Other Alaquods that have both:

1. Within 200 cm of the mineral soil surface, an argillic or

kandic horizon that has a base saturation of 35 percent or

more (by sum of cations) in some part; and

2. A sandy or sandy-skeletal particle-size class throughout

CHAPTER 14

Spodosols
252 Keys to Soil Taxonomy

a layer extending from the mineral soil surface to the top of a

spodic horizon at a depth of 75 to 125 cm.

Alfic Arenic Alaquods

CABE. Other Alaquods that have both:

1. An argillic or kandic horizon within 200 cm of the

mineral soil surface; and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

spodic horizon at a depth of 75 to 125 cm.

Arenic Ultic Alaquods

CABF. Other Alaquods that have both:

1. An umbric epipedon; and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

spodic horizon at a depth of 75 cm or more.

Arenic Umbric Alaquods

CABG. Other Alaquods that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a spodic horizon at a depth of

75 to 125 cm.

Arenic Alaquods

CABH. Other Alaquods that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a spodic horizon at a depth of

125 cm or more.

Grossarenic Alaquods

CABI. Other Alaquods that have, within 200 cm of the

mineral soil surface, an argillic or kandic horizon that has a base

saturation of 35 percent or more (by sum of cations) in some part.

Alfic Alaquods

CABJ. Other Alaquods that have an argillic or kandic horizon

within 200 cm of the mineral soil surface.

Ultic Alaquods

CABK. Other Alaquods that have an ochric epipedon.

Aeric Alaquods

CABL. Other Alaquods.

Typic Alaquods

Cryaquods

Key to Subgroups

CAAA. Cryaquods that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Cryaquods

CAAB. Other Cryaquods that have a placic horizon within

100 cm of the mineral soil surface in 50 percent or more of each

pedon.

Placic Cryaquods

CAAC. Other Cryaquods that have, in 90 percent or more of

each pedon, a cemented soil layer that does not slake in water

after air drying and has its upper boundary within 100 cm of the

mineral soil surface.

Duric Cryaquods

CAAD. Other Cryaquods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Cryaquods

CAAE. Other Cryaquods that have a spodic horizon less than

10 cm thick in 50 percent or more of each pedon.

Entic Cryaquods

CAAF. Other Cryaquods.

Typic Cryaquods

Duraquods

Key to Subgroups

CAEA. Duraquods that have a histic epipedon.

Histic Duraquods

CAEB. Other Duraquods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Duraquods

CAEC. Other Duraquods.

Typic Duraquods

Endoaquods

Key to Subgroups

CAGA. Endoaquods that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Endoaquods

CAGB. Other Endoaquods that have a histic epipedon.

Histic Endoaquods

CAGC. Other Endoaquods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or
Spodosols 253

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more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Endoaquods

CAGD. Other Endoaquods that have an argillic or kandic

horizon within 200 cm of the mineral soil surface.

Argic Endoaquods

CAGE. Other Endoaquods that have an umbric epipedon.

Umbric Endoaquods

CAGF. Other Endoaquods.

Typic Endoaquods

Epiaquods

Key to Subgroups

CAFA. Epiaquods that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Epiaquods

CAFB. Other Epiaquods that have a histic epipedon.

Histic Epiaquods

CAFC. Other Epiaquods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Epiaquods

CAFD. Other Epiaquods that have, within 200 cm of the

mineral soil surface, an argillic or kandic horizon that has a base

saturation of 35 percent or more (by sum of cations) in some part.

Alfic Epiaquods

CAFE. Other Epiaquods that have an argillic or kandic

horizon within 200 cm of the mineral soil surface.

Ultic Epiaquods

CAFF. Other Epiaquods that have an umbric epipedon.

Umbric Epiaquods

CAFG. Other Epiaquods.

Typic Epiaquods

Fragiaquods

Key to Subgroups

CACA. Fragiaquods that have a histic epipedon.

Histic Fragiaquods

CACB. Other Fragiaquods that have a surface horizon 30 cm

or more thick that meets all of the requirements for a plaggen

epipedon except thickness.

Plagganthreptic Fragiaquods

CACC. Other Fragiaquods that have an argillic or kandic

horizon within 200 cm of the mineral soil surface.

Argic Fragiaquods

CACD. Other Fragiaquods.

Typic Fragiaquods

Placaquods

Key to Subgroups

CADA. Placaquods that have andic soil properties throughout

horizons that have a total thickness of 25 cm or more within 75

cm either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Andic Placaquods

CADB. Other Placaquods.

Typic Placaquods

Cryods

Key to Great Groups

CCA. Cryods that have a placic horizon within 100 cm of

the mineral soil surface in 50 percent or more of each pedon.

Placocryods, p. 255

CCB. Other Cryods that have, in 90 percent or more of each

pedon, a cemented soil layer that does not slake in water after

air drying and has its upper boundary within 100 cm of the

mineral soil surface.

Duricryods, p. 253

CCC. Other Cryods that have 6.0 percent or more organic

carbon throughout a layer 10 cm or more thick within the

spodic horizon.

Humicryods, p. 254

CCD. Other Cryods.

Haplocryods, p. 254

Duricryods

Key to Subgroups

CCBA. Duricryods that have both:

1. Redoximorphic features in one or more horizons

within 75 cm of the mineral soil surface and also aquic
254 Keys to Soil Taxonomy

conditions for some time in normal years (or artificial

drainage); and

2. Andic soil properties throughout horizons that have a

total thickness of 25 cm or more within 75 cm either of the

mineral soil surface or of the top of an organic layer with

andic soil properties, whichever is shallower.

Aquandic Duricryods

CCBB. Other Duricryods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Duricryods

CCBC. Other Duricryods that have redoximorphic features in

one or more horizons within 75 cm of the mineral soil surface

and also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Duricryods

CCBD. Other Duricryods that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Duricryods

CCBE. Other Duricryods that have 6.0 percent or more

organic carbon throughout a layer 10 cm or more thick within

the spodic horizon.

Humic Duricryods

CCBF. Other Duricryods.

Typic Duricryods

Haplocryods

Key to Subgroups

CCDA. Haplocryods that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haplocryods

CCDB. Other Haplocryods that have both:

1. Redoximorphic features in one or more horizons

within 75 cm of the mineral soil surface and also aquic

conditions for some time in normal years (or artificial

drainage); and

2. Andic soil properties throughout horizons that have a

total thickness of 25 cm or more within 75 cm either of the

mineral soil surface or of the top of an organic layer with

andic soil properties, whichever is shallower.

Aquandic Haplocryods

CCDC. Other Haplocryods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Haplocryods

CCDD. Other Haplocryods that have redoximorphic features

in one or more horizons within 75 cm of the mineral soil

surface and also aquic conditions for some time in normal years

(or artificial drainage).

Aquic Haplocryods

CCDE. Other Haplocryods that are saturated with water in

one or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplocryods

CCDF. Other Haplocryods that have 1.1 percent or less

organic carbon in the upper 10 cm of the spodic horizon.

Entic Haplocryods

CCDG. Other Haplocryods.

Typic Haplocryods

Humicryods

Key to Subgroups

CCCA. Humicryods that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Humicryods

CCCB. Other Humicryods that have both:

1. Redoximorphic features in one or more horizons

within 75 cm of the mineral soil surface and also aquic

conditions for some time in normal years (or artificial

drainage); and

2. Andic soil properties throughout horizons that have a

total thickness of 25 cm or more within 75 cm either of the

mineral soil surface or of the top of an organic layer with

andic soil properties, whichever is shallower.

Aquandic Humicryods
Spodosols 255

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CCCC. Other Humicryods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Humicryods

CCCD. Other Humicryods that have redoximorphic features

in one or more horizons within 75 cm of the mineral soil

surface and also aquic conditions for some time in normal years

(or artificial drainage).

Aquic Humicryods

CCCE. Other Humicryods that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Humicryods

CCCF. Other Humicryods.

Typic Humicryods

Placocryods

Key to Subgroups

CCAA. Placocryods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Placocryods

CCAB. Other Placocryods that have 6.0 percent or more

organic carbon in a layer 10 cm or more thick within the spodic

horizon.

Humic Placocryods

CCAC. Other Placocryods.

Typic Placocryods

Gelods

Key to Great Groups

CBA. Gelods that have 6.0 percent or more organic carbon

throughout a layer 10 cm or more thick within the spodic

horizon.

Humigelods, p. 255

CBB. Other Gelods.

Haplogelods, p. 255

Haplogelods

Key to Subgroups

CBBA. Haplogelods that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haplogelods

CBBB. Other Haplogelods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

 Andic Haplogelods

CBBC. Other Haplogelods that have redoximorphic features

in one or more horizons within 75 cm of the mineral soil

surface and also aquic conditions for some time in normal years

(or artificial drainage).

Aquic Haplogelods

CBBD. Other Haplogelods.

Typic Haplogelods

Humigelods

Key to Subgroups

CBAA. Humigelods that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Humigelods

CBAB. Other Humigelods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Humigelods

CBAC. Other Humigelods that have redoximorphic features

in one or more horizons within 75 cm of the mineral soil

surface and also aquic conditions for some time in normal years

(or artificial drainage).

Aquic Humigelods

CBAD. Other Humigelods.

Typic Humigelods
256 Keys to Soil Taxonomy

Humods

Key to Great Groups

CDA. Humods that have a placic horizon within 100 cm of

the mineral soil surface in 50 percent or more of each pedon.

Placohumods, p. 256

CDB. Other Humods that have, in 90 percent or more of each

pedon, a cemented soil layer that does not slake in water after

air drying and has its upper boundary within 100 cm of the

mineral soil surface.

Durihumods, p. 256

CDC. Other Humods that have a fragipan with its upper

boundary within 100 cm of the mineral soil surface.

Fragihumods, p. 256

CDD. Other Humods.

Haplohumods, p. 256

Durihumods

Key to Subgroups

CDBA. Durihumods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Durihumods

CDBB. Other Durihumods.

Typic Durihumods

Fragihumods

Key to Subgroups

CDCA. All Fragihumods (provisionally).

Typic Fragihumods

Haplohumods

Key to Subgroups

CDDA. Haplohumods that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Haplohumods

CDDB. Other Haplohumods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Haplohumods

CDDC. Other Haplohumods that have a surface horizon 30

cm or more thick that meets all of the requirements for a

plaggen epipedon except thickness.

Plagganthreptic Haplohumods

CDDD. Other Haplohumods.

Typic Haplohumods

Placohumods

Key to Subgroups

CDAA. Placohumods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Placohumods

CDAB. Other Placohumods.

Typic Placohumods

Orthods

Key to Great Groups

CEA. Orthods that have, in 50 percent or more of each pedon,

a placic horizon within 100 cm of the mineral soil surface.

Placorthods, p. 259

CEB. Other Orthods that have, in 90 percent or more of each

pedon, a cemented soil layer that does not slake in water after

air drying and has its upper boundary within 100 cm of the

mineral soil surface.

Durorthods, p. 257

CEC. Other Orthods that have a fragipan with its upper

boundary within 100 cm of the mineral soil surface.

Fragiorthods, p. 257

CED. Other Orthods that have less than 0.10 percent iron (by

ammonium oxalate) in 75 percent or more of the spodic horizon.

Alorthods, p. 257

CEE. Other Orthods.

Haplorthods, p. 258
Spodosols 257

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Alorthods

Key to Subgroups

CEDA. Alorthods that are saturated with water in one or more

layers within 100 cm of the mineral soil surface in normal years

for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Alorthods

CEDB. Other Alorthods that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

spodic horizon at a depth of 75 to 125 cm; and

2. An argillic or kandic horizon below the spodic horizon.

Arenic Ultic Alorthods

CEDC. Other Alorthods that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a spodic horizon at a depth of

75 to 125 cm.

Arenic Alorthods

CEDD. Other Alorthods that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

spodic horizon at a depth of 125 cm or more; and

2. In 10 percent or more of each pedon, less than 3.0

percent organic carbon in the upper 2 cm of the spodic

horizon.

Entic Grossarenic Alorthods

CEDE. Other Alorthods that have, in 10 percent or more of

each pedon, less than 3.0 percent organic carbon in the upper 2

cm of the spodic horizon.

Entic Alorthods

CEDF. Other Alorthods that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a spodic horizon at a depth of

125 cm or more.

Grossarenic Alorthods

CEDG. Other Alorthods that have a surface horizon 30 cm or

more thick that meets all of the requirements for a plaggen

epipedon except thickness.

Plagganthreptic Alorthods

CEDH. Other Alorthods that have, within 200 cm of the

mineral soil surface, an argillic or kandic horizon that has a

base saturation of 35 percent or more (by sum of cations) in

some part.

Alfic Alorthods

CEDI. Other Alorthods that have an argillic or kandic horizon

within 200 cm of the mineral soil surface.

Ultic Alorthods

CEDJ. Other Alorthods.

Typic Alorthods

Durorthods

Key to Subgroups

CEBA. Durorthods that have andic soil properties throughout

horizons that have a total thickness of 25 cm or more within 75

cm either of the mineral soil surface or of the top of an organic

layer with andic soil properties, whichever is shallower.

Andic Durorthods

CEBB. Other Durorthods.

Typic Durorthods

Fragiorthods

Key to Subgroups

CECA. Fragiorthods that have redoximorphic features in one

or more horizons within 75 cm of the mineral soil surface and

also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Fragiorthods

CECB. Other Fragiorthods that:

1. Are saturated with water in one or more layers within

100 cm of the mineral soil surface in normal years for either

or both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days; and

2. Have, within 200 cm of the mineral soil surface, an

argillic or kandic horizon that has a base saturation of 35

percent or more (by sum of cations) in some part.

Alfic Oxyaquic Fragiorthods

CECC. Other Fragiorthods that are saturated with water in

one or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Fragiorthods
258 Keys to Soil Taxonomy

CECD. Other Fragiorthods that have a surface horizon 30 cm

or more thick that meets all of the requirements for a plaggen

epipedon except thickness.

Plagganthreptic Fragiorthods

CECE. Other Fragiorthods that have, within 200 cm of the

mineral soil surface, an argillic or kandic horizon that has a base

saturation of 35 percent or more (by sum of cations) in some part.

Alfic Fragiorthods

CECF. Other Fragiorthods that have an argillic or kandic

horizon within 200 cm of the mineral soil surface.

Ultic Fragiorthods

CECG. Other Fragiorthods that have a spodic horizon that has

one of the following:

1. A texture of very fine sand, loamy very fine sand, or

finer; and

a. A thickness of 10 cm or less; and

b. A weighted average of less than 1.2 percent organic

carbon; and

c. Within the upper 7.5 cm, either or both a moist color

value or chroma of 4 or more (crushed and smoothed

sample); or

2. A texture of loamy fine sand, fine sand, or coarser and

either or both a moist color value or chroma of 4 or more

(crushed and smoothed sample) in the upper 2.5 cm.

Entic Fragiorthods

CECH. Other Fragiorthods.

Typic Fragiorthods

Haplorthods

Key to Subgroups

CEEA. Haplorthods that have a lithic contact within 50 cm of

the mineral soil surface; and either

1. A spodic horizon with a texture of very fine sand, loamy

very fine sand, or finer; and

a. A thickness of 10 cm or less; and

b. A weighted average of less than 1.2 percent organic

carbon; and

c. Within the upper 7.5 cm, either or both a moist color

value or chroma of 4 or more (crushed and smoothed

sample); or

2. A spodic horizon with a texture of loamy fine sand, fine

sand, or coarser and either or both a moist color value or

chroma of 4 or more (crushed and smoothed sample) in the

upper 2.5 cm.

Entic Lithic Haplorthods

CEEB. Other Haplorthods that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Haplorthods

CEEC. Other Haplorthods that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. Redoximorphic features in one or more horizons within

75 cm of the mineral soil surface and also aquic conditions

for some time in normal years (or artificial drainage).

Fragiaquic Haplorthods

CEED. Other Haplorthods that have both:

1. Redoximorphic features in one or more horizons

within 75 cm of the mineral soil surface and also aquic

conditions for some time in normal years (or artificial

drainage); and

2. Within 200 cm of the mineral soil surface, an argillic or

kandic horizon that has a base saturation of 35 percent or

more (by sum of cations) in some part.

Aqualfic Haplorthods

CEEE. Other Haplorthods that have redoximorphic features in

one or more horizons within 75 cm of the mineral soil surface

and also aquic conditions for some time in normal years (or

artificial drainage); and either

1. A spodic horizon with a texture of very fine sand, loamy

very fine sand, or finer; and

a. A thickness of 10 cm or less; and

b. A weighted average of less than 1.2 percent organic

carbon; and

c. Within the upper 7.5 cm, either or both a moist color

value or chroma of 4 or more (crushed and smoothed

sample); or

2. A spodic horizon with a texture of loamy fine sand, fine

sand, or coarser and either or both a moist color value or

chroma of 4 or more (crushed and smoothed sample) in the

upper 2.5 cm.

Aquentic Haplorthods
Spodosols 259

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CEEF. Other Haplorthods that have redoximorphic features in

one or more horizons within 75 cm of the mineral soil surface

and also aquic conditions for some time in normal years (or

artificial drainage).

Aquic Haplorthods

CEEG. Other Haplorthods that have:

1. Within 200 cm of the mineral soil surface, an argillic or

kandic horizon that has a base saturation of 35 percent or

more (by sum of cations) in some part; and

2. Saturation with water in one or more layers within 100 cm

of the mineral soil surface in normal years for either or both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Alfic Oxyaquic Haplorthods

CEEH. Other Haplorthods that have:

1. Within 200 cm of the mineral soil surface, an argillic or

kandic horizon; and

2. Saturation with water in one or more layers within 100 cm

of the mineral soil surface in normal years for either or both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Oxyaquic Ultic Haplorthods

CEEI. Other Haplorthods that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Haplorthods

CEEJ.Other Haplorthods that have both:

1. Saturation with water in 1 or more layers within 100 cm

of the mineral soil surface in normal years for either or both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days; and

2. Below the spodic horizon but not below an argillic

horizon, lamellae (two or more) within 200 cm of the

mineral soil surface.

Lamellic Oxyaquic Haplorthods

CEEK. Other Haplorthods that, below the spodic horizon but

not below an argillic horizon, have lamellae (two or more)

within 200 cm of the mineral soil surface.

Lamellic Haplorthods

CEEL. Other Haplorthods that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplorthods

CEEM. Other Haplorthods that have andic soil properties

throughout horizons that have a total thickness of 25 cm or

more within 75 cm either of the mineral soil surface or of the

top of an organic layer with andic soil properties, whichever is

shallower.

Andic Haplorthods

CEEN. Other Haplorthods that have, within 200 cm of the

mineral soil surface, an argillic or kandic horizon that has a

base saturation of 35 percent or more (by sum of cations) in

some part.

Alfic Haplorthods

CEEO. Other Haplorthods that have an argillic or kandic

horizon within 200 cm of the mineral soil surface.

Ultic Haplorthods

CEEP. Other Haplorthods that have a spodic horizon that has

one of the following:

1. A texture of very fine sand, loamy very fine sand, or

finer; and

a. A thickness of 10 cm or less; and

b. A weighted average of less than 1.2 percent organic

carbon; and

c. Within the upper 7.5 cm, either or both a moist color

value or chroma of 4 or more (crushed and smoothed

sample); or

2. A texture of loamy fine sand, fine sand, or coarser

and either or both a moist color value or chroma of 4

or more (crushed and smoothed sample) in the upper 2.5

cm.

Entic Haplorthods

CEEQ. Other Haplorthods.

Typic Haplorthods

Placorthods

Key to Subgroups

CEAA. All Placorthods (provisionally).

Typic Placorthods

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Key to Suborders

HA. Ultisols that have aquic conditions for some time in

normal years (or artificial drainage) in one or more horizons

within 50 cm of the mineral soil surface and one or both of the

following:

1. Redoximorphic features in all layers between either the

lower boundary of an Ap horizon or a depth of 25 cm from

the mineral soil surface, whichever is deeper, and a depth of

40 cm and one of the following within the upper 12.5 cm of

the argillic or kandic horizon:

a. Redox concentrations and 50 percent or more redox

depletions with chroma of 2 or less either on faces of peds

or in the matrix; or

b. 50 percent or more redox depletions with chroma of 1

or less either on faces of peds or in the matrix; or

c. Distinct or prominent redox concentrations and 50

percent or more hue of 2.5Y or 5Y in the matrix and also

a thermic, isothermic, or warmer soil temperature regime;

or

2. Within 50 cm of the mineral soil surface, enough active

ferrous iron to give a positive reaction to alpha,alphadipyridyl at a time when the soil is not being irrigated.

Aquults, p. 261

HB. Other Ultisols that have one or both of the following:

1. 0.9 percent (by weighted average) or more organic

carbon in the upper 15 cm of the argillic or kandic horizon;

or

2. 12 kg/m2 or more organic carbon between the mineral

soil surface and a depth of 100 cm.

Humults, p. 265

HC. Other Ultisols that have a udic moisture regime.

Udults, p. 268

HD. Other Ultisols that have an ustic moisture regime.

Ustults, p. 276

HE. Other Ultisols.

Xerults, p. 279

Aquults

Key to Great Groups

HAA. Aquults that have one or more horizons within 150 cm

of the mineral soil surface in which plinthite either forms a

continuous phase or constitutes one-half or more of the volume.

Plinthaquults, p. 265

HAB. Other Aquults that have a fragipan with an upper

boundary within 100 cm of the mineral soil surface.

Fragiaquults, p. 263

HAC. Other Aquults that have an abrupt textural change

between the ochric epipedon or albic horizon and the argillic or

kandic horizon and have 0.4 cm/hr or slower (moderately low

or lower) saturated hydraulic conductivity in the argillic or

kandic horizon.

Albaquults, p. 262

HAD. Other Aquults that:

1. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

2. Have a kandic horizon; and

3. Within 150 cm of the mineral soil surface, either:

a. With increasing depth, do not have a clay decrease of

20 percent or more (relative) from the maximum clay

content; or

b. Have 5 percent or more (by volume) clay depletions

on faces of peds in the layer that has a 20 percent lower

clay content and, below that layer, a clay increase of 3

percent or more (absolute) in the fine-earth fraction.

Kandiaquults, p. 263

HAE. Other Aquults that have a kandic horizon.

Kanhaplaquults, p. 263

HAF. Other Aquults that:

1. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

2. Within 150 cm of the mineral soil surface, either:

CHAPTER 15

Ultisols
262 Keys to Soil Taxonomy

a. With increasing depth, do not have a clay decrease of

20 percent or more (relative) from the maximum clay

content; or

b. Have 5 percent or more (by volume) clay depletions

on faces of peds in the layer that has a 20 percent lower

clay content and, below that layer, a clay increase of 3

percent or more (absolute) in the fine-earth fraction.

Paleaquults, p. 264

HAG. Other Aquults that have an umbric or mollic epipedon.

Umbraquults, p. 265

HAH. Other Aquults that have episaturation.

Epiaquults, p. 262

HAI. Other Aquults.

Endoaquults, p. 262

Albaquults

Key to Subgroups

HACA. Albaquults that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that are

5 mm or more wide through a thickness of 30 cm or more

for some time in normal years and slickensides or wedgeshaped aggregates in a layer 15 cm or more thick that has its

upper boundary within 125 cm of the mineral soil surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Albaquults

HACB. Other Albaquults that have a kandic horizon.

Kandic Albaquults

HACC. Other Albaquults that have 50 percent or more

chroma of 3 or more in one or more horizons between either the

A or Ap horizon or a depth of 25 cm from the mineral soil

surface, whichever is deeper, and a depth of 75 cm.

Aeric Albaquults

HACD. Other Albaquults.

Typic Albaquults

Endoaquults

Key to Subgroups

HAIA. Endoaquults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm.

Arenic Endoaquults

HAIB. Other Endoaquults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 100 cm or more.

Grossarenic Endoaquults

HAIC. Other Endoaquults that have 50 percent or more

chroma of 3 or more in one or more horizons between either the

A or Ap horizon or a depth of 25 cm from the mineral soil

surface, whichever is deeper, and a depth of 75 cm.

Aeric Endoaquults

HAID. Other Endoaquults.

Typic Endoaquults

Epiaquults

Key to Subgroups

HAHA. Epiaquults that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Epiaquults

HAHB. Other Epiaquults that have:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. 50 percent or more chroma of 3 or more in one or more

horizons between either the A or Ap horizon or a depth of 25

cm from the mineral soil surface, whichever is deeper, and a

depth of 75 cm.

Aeric Fragic Epiaquults

HAHC. Other Epiaquults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm.

Arenic Epiaquults

HAHD. Other Epiaquults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the
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mineral soil surface to the top of an argillic horizon at a depth

of 100 cm or more.

Grossarenic Epiaquults

HAHE. Other Epiaquults that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Epiaquults

HAHF. Other Epiaquults that have 50 percent or more chroma

of 3 or more in one or more horizons between either the A or

Ap horizon or a depth of 25 cm from the mineral soil surface,

whichever is deeper, and a depth of 75 cm.

Aeric Epiaquults

HAHG. Other Epiaquults.

Typic Epiaquults

Fragiaquults

Key to Subgroups

HABA. Fragiaquults that have 50 percent or more chroma of

3 or more in one or more horizons between either the A or Ap

horizon or a depth of 25 cm from the mineral soil surface,

whichever is deeper, and the fragipan.

Aeric Fragiaquults

HABB. Other Fragiaquults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Fragiaquults

HABC. Other Fragiaquults that have a mollic or umbric

epipedon.

Umbric Fragiaquults

HABD. Other Fragiaquults.

Typic Fragiaquults

Kandiaquults

Key to Subgroups

HADA. Kandiaquults that have an ECEC of 1.5 cmol(+)/kg

clay or less (sum of bases extracted with 1N NH4OAc pH 7,

plus 1N KCl-extractable Al) in one or more horizons within 150

cm of the mineral soil surface.

Acraquoxic Kandiaquults

HADB. Other Kandiaquults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 50 to 100 cm; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Arenic Plinthic Kandiaquults

HADC. Other Kandiaquults that:

1. Have a mollic or umbric epipedon; and

2. Have a sandy or sandy-skeletal particle-size class

throughout a layer extending from the mineral soil surface to

the top of a kandic horizon at a depth of 50 to 100 cm.

Arenic Umbric Kandiaquults

HADD. Other Kandiaquults that have a sandy or sandyskeletal particle-size class throughout a layer extending from

the mineral soil surface to the top of a kandic horizon at a depth

of 50 to 100 cm.

Arenic Kandiaquults

HADE. Other Kandiaquults that have a sandy or sandyskeletal particle-size class throughout a layer extending from

the mineral soil surface to the top of a kandic horizon at a depth

of 100 cm or more.

Grossarenic Kandiaquults

HADF. Other Kandiaquults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kandiaquults

HADG. Other Kandiaquults that have 50 percent or more

chroma of 3 or more in one or more horizons between either the

A or Ap horizon or a depth of 25 cm from the mineral soil

surface, whichever is deeper, and a depth of 75 cm.

Aeric Kandiaquults

HADH. Other Kandiaquults that have a mollic or umbric

epipedon.

Umbric Kandiaquults

HADI. Other Kandiaquults.

Typic Kandiaquults

Kanhaplaquults

Key to Subgroups

HAEA. Kanhaplaquults that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, one or more of the following:

1. A fine-earth fraction with both a bulk density of 1.0
264 Keys to Soil Taxonomy

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; or

2. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

3. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

a. In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

b. [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Kanhaplaquults

HAEB. Other Kanhaplaquults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kanhaplaquults

HAEC. Other Kanhaplaquults that:

1. Have a mollic or umbric epipedon; and

2. Have 50 percent or more chroma of 3 or more in one or

more horizons between either the A or Ap horizon or a depth

of 25 cm from the mineral soil surface, whichever is deeper,

and a depth of 75 cm.

Aeric Umbric Kanhaplaquults

HAED. Other Kanhaplaquults that have 50 percent or more

chroma of 3 or more in one or more horizons between either the

A or Ap horizon or a depth of 25 cm from the mineral soil

surface, whichever is deeper, and a depth of 75 cm.

Aeric Kanhaplaquults

HAEE. Other Kanhaplaquults that have a mollic or umbric

epipedon.

Umbric Kanhaplaquults

HAEF. Other Kanhaplaquults.

Typic Kanhaplaquults

Paleaquults

Key to Subgroups

HAFA. Paleaquults that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Paleaquults

HAFB. Other Paleaquults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 to 100 cm; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Arenic Plinthic Paleaquults

HAFC. Other Paleaquults that:

1. Have a mollic or umbric epipedon; and

2. Have a sandy or sandy-skeletal particle-size class

throughout a layer extending from the mineral soil surface to

the top of an argillic horizon at a depth of 50 to 100 cm.

Arenic Umbric Paleaquults

HAFD. Other Paleaquults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm.

Arenic Paleaquults

HAFE. Other Paleaquults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 100 cm or more.

Grossarenic Paleaquults

HAFF. Other Paleaquults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Paleaquults

HAFG. Other Paleaquults that have 50 percent or more

chroma of 3 or more in one or more horizons between either the

A or Ap horizon or a depth of 25 cm from the mineral soil

surface, whichever is deeper, and a depth of 75 cm.

Aeric Paleaquults

HAFH. Other Paleaquults that have a mollic or umbric

epipedon.

Umbric Paleaquults

HAFI. Other Paleaquults.

Typic Paleaquults
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Plinthaquults

Key to Subgroups

HAAA. Plinthaquults that have a kandic horizon or a CEC

(by 1N NH4OAc pH 7) of less than 24 cmol(+)/kg clay in 50

percent or more (by volume) of the argillic horizon if less than

100 cm thick or of its upper 100 cm.

Kandic Plinthaquults

HAAB. Other Plinthaquults.

Typic Plinthaquults

Umbraquults

Key to Subgroups

HAGA. Umbraquults that have 5 to 50 percent (by volume)

plinthite in one or more horizons within 150 cm of the mineral

soil surface.

Plinthic Umbraquults

HAGB. Other Umbraquults.

Typic Umbraquults

Humults

Key to Great Groups

HBA. Humults that have a sombric horizon within 100 cm of

the mineral soil surface.

Sombrihumults, p. 268

HBB. Other Humults that have one or more horizons within

150 cm of the mineral soil surface in which plinthite either

forms a continuous phase or constitutes one-half or more of the

volume.

Plinthohumults, p. 268

HBC. Other Humults that:

1. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

2. Have a kandic horizon; and

3. Within 150 cm of the mineral soil surface, either:

a. With increasing depth, do not have a clay decrease of

20 percent or more (relative) from the maximum clay

content; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction.

Kandihumults, p. 266

HBD. Other Humults that have a kandic horizon.

Kanhaplohumults, p. 267

HBE. Other Humults that:

1. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

2. Within 150 cm of the mineral soil surface, either:

a. With increasing depth, do not have a clay decrease of

20 percent or more (relative) from the maximum clay

content; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction.

Palehumults, p. 267

HBF. Other Humults.

Haplohumults, p. 265

Haplohumults

Key to Subgroups

HBFA. Haplohumults that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Haplohumults

HBFB. Other Haplohumults that have both:

1. In one or more subhorizons within the upper 25 cm of

the argillic horizon, redox depletions with a color value,

moist, of 4 or more and chroma of 2 or less, accompanied by

redox concentrations, and also aquic conditions for some

time in normal years (or artificial drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

a fine-earth fraction with both a bulk density of 1.0 g/cm3

or less, measured at 33 kPa water retention, and Al plus

1

/2 Fe percentages (by ammonium oxalate) totaling more than

1.0.

Aquandic Haplohumults

HBFC. Other Haplohumults that have, in one or more

subhorizons within the upper 25 cm of the argillic horizon,

redox depletions with a color value, moist, of 4 or more and

chroma of 2 or less, accompanied by redox concentrations and

by aquic conditions for some time in normal years (or artificial

drainage).

Aquic Haplohumults

HBFD. Other Haplohumults that have, throughout one or

more horizons with a total thickness of 18 cm or more within
266 Keys to Soil Taxonomy

75 cm of the mineral soil surface, a fine-earth fraction with both

a bulk density of 1.0 g/cm3 or less, measured at 33 kPa water

retention, and Al plus 1/2 Fe percentages (by ammonium

oxalate) totaling more than 1.0.

Andic Haplohumults

HBFE. Other Haplohumults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Haplohumults

HBFF. Other Haplohumults that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Haplohumults

HBFG. Other Haplohumults that have an ustic moisture

regime.

Ustic Haplohumults

HBFH. Other Haplohumults that have a xeric moisture regime.

Xeric Haplohumults

HBFI. Other Haplohumults.

Typic Haplohumults

Kandihumults

Key to Subgroups

HBCA. Kandihumults that meet all of the following:

1. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

have a fine-earth fraction with both a bulk density of 1.0

g/cm3 or less, measured at 33 kPa water retention, and Al

plus 1/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0; and

2. In one or more horizons within 75 cm of the mineral soil

surface, have redox concentrations, a color value, moist, of 4

or more, and hue that is 10YR or yellower and becomes

redder with increasing depth within 100 cm of the mineral

soil surface; and

3. In normal years are saturated with water in one or more

layers within 100 cm of the mineral soil surface for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Andic Ombroaquic Kandihumults

HBCB. Other Kandihumults that have both:

1. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface, a

fine-earth fraction with both a bulk density of 1.0 g/cm3

 or

less, measured at 33 kPa water retention, and Al plus 1/2 Fe

percentages (by ammonium oxalate) totaling more than 1.0;

and

2. An ustic moisture regime.

Ustandic Kandihumults

HBCC. Other Kandihumults that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction with both

a bulk density of 1.0 g/cm3

 or less, measured at 33 kPa water

retention, and Al plus 1/2 Fe percentages (by ammonium

oxalate) totaling more than 1.0.

Andic Kandihumults

HBCD. Other Kandihumults that have, in one or more

subhorizons within the upper 25 cm of the kandic horizon,

redox depletions with a color value, moist, of 4 or more and

chroma of 2 or less, accompanied by redox concentrations and

by aquic conditions for some time in normal years (or artificial

drainage).

Aquic Kandihumults

HBCE. Other Kandihumults that:

1. Have, in one or more horizons within 75 cm of the

mineral soil surface, redox concentrations, a color value,

moist, of 4 or more, and hue that is 10YR or yellower and

becomes redder with increasing depth within 100 cm of the

mineral soil surface; and

2. In normal years are saturated with water in one or more

layers within 100 cm of the mineral soil surface for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Ombroaquic Kandihumults

HBCF. Other Kandihumults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kandihumults

HBCG. Other Kandihumults that have an ustic moisture

regime.

Ustic Kandihumults

HBCH. Other Kandihumults that have a xeric moisture regime.

Xeric Kandihumults
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HBCI. Other Kandihumults that have an anthropic epipedon.

Anthropic Kandihumults

HBCJ. Other Kandihumults.

Typic Kandihumults

Kanhaplohumults

Key to Subgroups

HBDA. Kanhaplohumults that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Kanhaplohumults

HBDB. Other Kanhaplohumults that have both:

1. An ustic moisture regime; and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface, a

fine-earth fraction with both a bulk density of 1.0 g/cm3

 or

less, measured at 33 kPa water retention, and Al plus 1/2 Fe

percentages (by ammonium oxalate) totaling more than 1.0.

Ustandic Kanhaplohumults

HBDC. Other Kanhaplohumults that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction with both

a bulk density of 1.0 g/cm3

 or less, measured at 33 kPa water

retention, and Al plus 1/2 Fe percentages (by ammonium

oxalate) totaling more than 1.0.

Andic Kanhaplohumults

HBDD. Other Kanhaplohumults that have, in one or more

subhorizons within the upper 25 cm of the kandic horizon,

redox depletions with a color value, moist, of 4 or more and

chroma of 2 or less, accompanied by redox concentrations and

by aquic conditions for some time in normal years (or artificial

drainage).

Aquic Kanhaplohumults

HBDE. Other Kanhaplohumults that:

1. Have, in one or more horizons within 75 cm of the

mineral soil surface, redox concentrations, a color value,

moist, of 4 or more, and hue that is 10YR or yellower and

becomes redder with increasing depth within 100 cm of the

mineral soil surface; and

2. In normal years are saturated with water in one or more

layers within 100 cm of the mineral soil surface for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Ombroaquic Kanhaplohumults

HBDF. Other Kanhaplohumults that have an ustic moisture

regime.

Ustic Kanhaplohumults

HBDG. Other Kanhaplohumults that have a xeric moisture

regime.

Xeric Kanhaplohumults

HBDH. Other Kanhaplohumults that have an anthropic

epipedon.

Anthropic Kanhaplohumults

HBDI. Other Kanhaplohumults.

Typic Kanhaplohumults

Palehumults

Key to Subgroups

HBEA. Palehumults that have both:

1. In one or more subhorizons within the upper 25 cm of

the argillic horizon, redox depletions with a color value,

moist, of 4 or more and chroma of 2 or less, accompanied by

redox concentrations, and also aquic conditions for some

time in normal years (or artificial drainage); and

2. Throughout one or more horizons with a total

thickness of 18 cm or more within 75 cm of the mineral

soil surface, a fine-earth fraction with both a bulk density

of 1.0 g/cm3 or less, measured at 33 kPa water retention, and

Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Aquandic Palehumults

HBEB. Other Palehumults that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Palehumults

HBEC. Other Palehumults that have, in one or more

subhorizons within the upper 25 cm of the argillic horizon,

redox depletions with a color value, moist, of 4 or more and

chroma of 2 or less, accompanied by redox concentrations and

by aquic conditions for some time in normal years (or artificial

drainage).

Aquic Palehumults

HBED. Other Palehumults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Palehumults
268 Keys to Soil Taxonomy

HBEE. Other Palehumults that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Palehumults

HBEF. Other Palehumults that have an ustic moisture regime.

Ustic Palehumults

HBEG. Other Palehumults that have a xeric moisture regime.

Xeric Palehumults

HBEH. Other Palehumults.

Typic Palehumults

Plinthohumults

Key to Subgroups

HBBA. All Plinthohumults.

Typic Plinthohumults

Sombrihumults

Key to Subgroups

HBAA. All Sombrihumults.

Typic Sombrihumults

Udults

Key to Great Groups

HCA. Udults that have one or more horizons within 150 cm

of the mineral soil surface in which plinthite either forms a

continuous phase or constitutes one-half or more of the volume.

Plinthudults, p. 275

HCB. Other Udults that have a fragipan with an upper

boundary within 100 cm of the mineral soil surface.

Fragiudults, p. 268

HCC. Other Udults that:

1. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

2. Have a kandic horizon; and

3. Within 150 cm of the mineral soil surface, either:

a. With increasing depth, do not have a clay decrease of

20 percent or more (relative) from the maximum clay

content; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction.

Kandiudults, p. 270

HCD. Other Udults that have a kandic horizon.

Kanhapludults, p. 272

HCE. Other Udults that:

1. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

2. Within 150 cm of the mineral soil surface, either:

a. With increasing depth, do not have a clay decrease of

20 percent or more (relative) from the maximum clay

content; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction.

Paleudults, p. 273

HCF. Other Udults that have both:

1. An epipedon that has a color value, moist, of 3 or less

throughout; and

2. In all subhorizons in the upper 100 cm of the argillic

horizon or throughout the entire argillic horizon if it is less

than 100 cm thick, more than 50 percent colors that have all

of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less; and

c. A dry value no more than 1 unit higher than the moist

value.

Rhodudults, p. 275

HCG. Other Udults.

Hapludults, p. 269

Fragiudults

Key to Subgroups

HCBA. Fragiudults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic or kandic horizon at

a depth of 50 to 100 cm.

Arenic Fragiudults

HCBB. Other Fragiudults that have both of the following:

1. In one or more horizons within 40 cm of the mineral soil

surface, redox depletions with chroma of 2 or less and also
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aquic conditions for some time in normal years (or artificial

drainage); and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Plinthaquic Fragiudults

HCBC. Other Fragiudults that meet both of the following:

1. Meet one or more of the following:

a. Have a glossic horizon above the fragipan; or

b. Do not have, above the fragipan, an argillic or kandic

horizon that has clay films on both vertical and horizontal

surfaces of any structural aggregates; or

c. Between the argillic or kandic horizon and the

fragipan, have one or more horizons with 50 percent or

more chroma of 3 or less and with a clay content 3

percent or more (absolute, in the fine-earth fraction) lower

than that in both the argillic or kandic horizon and the

fragipan; and

2. In one or more horizons within 40 cm of the mineral soil

surface, have redox depletions with chroma of 2 or less and

also aquic conditions for some time in normal years (or

artificial drainage).

Glossaquic Fragiudults

HCBD. Other Fragiudults that have, in one or more

subhorizons above the fragipan and within the upper 25 cm of

the argillic or kandic horizon, redox depletions with chroma of

2 or less and also aquic conditions for some time in normal

years (or artificial drainage).

Aquic Fragiudults

HCBE. Other Fragiudults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Fragiudults

HCBF. Other Fragiudults that meet one or more of the

following:

1. Have a glossic horizon above the fragipan; or

2. Do not have, above the fragipan, an argillic or kandic

horizon that has clay films on both vertical and horizontal

surfaces of any structural aggregates; or

3. Between the argillic or kandic horizon and the fragipan,

have one or more horizons with 50 percent or more chroma

of 3 or less and with a clay content 3 percent or more

(absolute, in the fine-earth fraction) lower than that in both

the argillic or kandic horizon and the fragipan.

Glossic Fragiudults

HCBG. Other Fragiudults that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) in either:

1. An Ap horizon that is 18 cm or more thick; or

2. The surface layer after mixing of the upper 18 cm.

Humic Fragiudults

HCBH. Other Fragiudults.

Typic Fragiudults

Hapludults

Key to Subgroups

HCGA. Hapludults that have either or both:

1. In each pedon, a discontinuous lithic contact within 50

cm of the mineral soil surface; and

2. In each pedon, a discontinuous argillic horizon that is

interrupted by ledges of bedrock.

Lithic-Ruptic-Entic Hapludults

HCGB. Other Hapludults that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Hapludults

HCGC. Other Hapludults that have one or both of the

following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Hapludults

HCGD. Other Hapludults that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. In one or more layers within 75 cm of the mineral soil

surface, redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less, accompanied by redox

concentrations, and also aquic conditions for some time in

normal years (or artificial drainage).

Fragiaquic Hapludults
270 Keys to Soil Taxonomy

HCGE. Other Hapludults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 to 100 cm; and

2. In one or more subhorizons within the upper 60 cm

of the argillic horizon, redox depletions with a color value,

moist, of 4 or more and chroma of 2 or less, accompanied by

redox concentrations, and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Arenic Hapludults

HCGF. Other Hapludults that have, in one or more

subhorizons within the upper 60 cm of the argillic horizon,

redox depletions with a color value, moist, of 4 or more and

chroma of 2 or less, accompanied by redox concentrations and

by aquic conditions for some time in normal years (or artificial

drainage).

Aquic Hapludults

HCGG. Other Hapludults that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Hapludults

HCGH. Other Hapludults that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Hapludults

HCGI. Other Hapludults that have an argillic horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more

than 20 cm thick, each with an overlying eluvial horizon,

and above these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Hapludults

HCGJ. Other Hapludults that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or throughout

the entire argillic horizon if it is less than 75 cm thick.

Psammentic Hapludults

HCGK. Other Hapludults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm.

Arenic Hapludults

HCGL. Other Hapludults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 100 cm or more.

Grossarenic Hapludults

HCGM. Other Hapludults that have:

1. No densic, lithic, or paralithic contact within 50 cm of

the mineral soil surface; and

2. An argillic horizon 25 cm or less thick.

Inceptic Hapludults

HCGN. Other Hapludults that have a color value, moist, of 3

or less and a color value, dry, of 5 or less (crushed and

smoothed sample) in either:

1. An Ap horizon that is 18 cm or more thick; or

2. The surface layer after mixing of the upper 18 cm.

Humic Hapludults

HCGO. Other Hapludults.

Typic Hapludults

Kandiudults

Key to Subgroups

HCCA. Kandiudults that have:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 50 to 100 cm; and

2. 5 percent or more (by volume) plinthite in one or

more horizons within 150 cm of the mineral soil surface; and

3. In one or more layers either within 75 cm of the mineral

soil surface or, if the chroma throughout the upper 75 cm
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results from uncoated sand grains, within the upper 12.5 cm

of the kandic horizon, redox depletions with a color value,

moist, of 4 or more and chroma of 2 or less, accompanied by

redox concentrations, and also aquic conditions for some

time in normal years (or artificial drainage).

Arenic Plinthaquic Kandiudults

HCCB. Other Kandiudults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 50 to 100 cm; and

2. In one or more layers either within 75 cm of the mineral

soil surface or, if the chroma throughout the upper 75 cm

results from uncoated sand grains, within the upper 12.5 cm

of the kandic horizon, redox depletions with a color value,

moist, of 4 or more and chroma of 2 or less, accompanied by

redox concentrations, and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Arenic Kandiudults

HCCC. Other Kandiudults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 50 to 100 cm; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Arenic Plinthic Kandiudults

HCCD. Other Kandiudults that have both:

1. A sandy or sandy-skeletal particle-size class

throughout a layer extending from the mineral soil surface

to the top of a kandic horizon at a depth of 50 to 100 cm;

and

2. In all subhorizons in the upper 75 cm of the kandic

horizon or throughout the entire kandic horizon if it is less

than 75 cm thick, more than 50 percent colors that have all

of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less; and

c. A dry value no more than 1 unit higher than the moist

value.

Arenic Rhodic Kandiudults

HCCE. Other Kandiudults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a kandic horizon at a depth of

50 to 100 cm.

Arenic Kandiudults

HCCF. Other Kandiudults that have both:

1. A sandy or sandy-skeletal particle-size class

throughout a layer extending from the mineral soil surface to

the top of a kandic horizon at a depth of 100 cm or more;

and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Grossarenic Plinthic Kandiudults

HCCG. Other Kandiudults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of a kandic horizon at a depth of

100 cm or more.

Grossarenic Kandiudults

HCCH. Other Kandiudults that have both:

1. An ECEC of 1.5 cmol(+)/kg clay or less (sum of bases

extracted with 1N NH4

OAc pH 7, plus 1N KCl-extractable

Al) in one or more horizons within 150 cm of the mineral

soil surface; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Acrudoxic Plinthic Kandiudults

HCCI. Other Kandiudults that have an ECEC of 1.5

cmol(+)/kg clay or less (sum of bases extracted with 1N

NH4

OAc pH 7, plus 1N KCl-extractable Al) in one or more

horizons within 150 cm of the mineral soil surface.

Acrudoxic Kandiudults

HCCJ. Other Kandiudults that have both:

1. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface; and

2. In one or more layers within 75 cm of the mineral soil

surface, redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less, accompanied by redox

concentrations, and also aquic conditions for some time in

normal years (or artificial drainage).

Plinthaquic Kandiudults

HCCK. Other Kandiudults that have both:

1. In one or more layers within 75 cm of the mineral soil

surface, redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less, accompanied by redox

concentrations, and also aquic conditions for some time in

normal years (or artificial drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

one or more of the following:

a. A fine-earth fraction with both a bulk density of 1.0

g/cm3

 or less, measured at 33 kPa water retention, and Al
272 Keys to Soil Taxonomy

plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0; or

b. More than 35 percent (by volume) fragments coarser

than 2.0 mm, of which more than 66 percent is cinders,

pumice, and pumicelike fragments; or

c. A fine-earth fraction containing 30 percent or more

particles 0.02 to 2.0 mm in diameter; and

(1) In the 0.02 to 2.0 mm fraction, 5 percent or more

volcanic glass; and

(2) [(Al plus 1/2 Fe, percent extracted by ammonium

oxalate) times 60] plus the volcanic glass (percent) is

equal to 30 or more.

Aquandic Kandiudults

HCCL. Other Kandiudults that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Kandiudults

HCCM. Other Kandiudults that have, in one or more layers

within 75 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less,

accompanied by redox concentrations and by aquic conditions

for some time in normal years (or artificial drainage).

Aquic Kandiudults

HCCN. Other Kandiudults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kandiudults

HCCO. Other Kandiudults that:

1. Have, in one or more horizons within 75 cm of the

mineral soil surface, redox concentrations, a color value,

moist, of 4 or more, and hue that is 10YR or yellower and

becomes redder with increasing depth within 100 cm of the

mineral soil surface; and

2. In normal years are saturated with water in one or more

layers within 100 cm of the mineral soil surface for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Ombroaquic Kandiudults

HCCP. Other Kandiudults that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Kandiudults

HCCQ. Other Kandiudults that have a sombric horizon within

150 cm of the mineral soil surface.

Sombric Kandiudults

HCCR. Other Kandiudults that have, in all subhorizons in the

upper 75 cm of the kandic horizon or throughout the entire

kandic horizon if it is less than 75 cm thick, more than 50

percent colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less; and

3. A dry value no more than 1 unit higher than the moist

value.

Rhodic Kandiudults

HCCS. Other Kandiudults.

Typic Kandiudults

Kanhapludults

Key to Subgroups

HCDA. Kanhapludults that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Kanhapludults

HCDB. Other Kanhapludults that have both:

1. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface; and

2. In one or more layers within 75 cm of the mineral soil

surface, redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less, accompanied by redox

concentrations, and also aquic conditions for some time in

normal years (or artificial drainage).

Plinthaquic Kanhapludults

HCDC. Other Kanhapludults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 50 to 100 cm; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Arenic Plinthic Kanhapludults
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HCDD. Other Kanhapludults that have a sandy or sandyskeletal particle-size class throughout a layer extending from

the mineral soil surface to the top of a kandic horizon at a depth

of 50 to 100 cm.

Arenic Kanhapludults

HCDE. Other Kanhapludults that have an ECEC of 1.5

cmol(+)/kg clay or less (sum of bases extracted with 1N

NH4

OAc pH 7, plus 1N KCl-extractable Al) in one or more

horizons within 150 cm of the mineral soil surface.

Acrudoxic Kanhapludults

HCDF. Other Kanhapludults that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. In one or more layers within 75 cm of the mineral soil

surface, redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less, accompanied by redox

concentrations, and also aquic conditions for some time in

normal years (or artificial drainage).

Fragiaquic Kanhapludults

HCDG. Other Kanhapludults that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction with both

a bulk density of 1.0 g/cm3

 or less, measured at 33 kPa water

retention, and Al plus 1/2 Fe percentages (by ammonium

oxalate) totaling more than 1.0.

Andic Kanhapludults

HCDH. Other Kanhapludults that have, in one or more layers

within 75 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less,

accompanied by redox concentrations and by aquic conditions

for some time in normal years (or artificial drainage).

Aquic Kanhapludults

HCDI. Other Kanhapludults that:

1. Have, in one or more horizons within 75 cm of the

mineral soil surface, redox concentrations, a color value,

moist, of 4 or more, and hue that is 10YR or yellower and

becomes redder with increasing depth within 100 cm of the

mineral soil surface; and

2. In normal years are saturated with water in one or more

layers within 100 cm of the mineral soil surface for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Ombroaquic Kanhapludults

HCDJ. Other Kanhapludults that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Kanhapludults

HCDK. Other Kanhapludults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kanhapludults

HCDL. Other Kanhapludults that have fragic soil

properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Kanhapludults

HCDM. Other Kanhapludults that have, in all subhorizons in

the upper 50 cm of the kandic horizon or throughout the entire

kandic horizon if it is less than 50 cm thick, more than 50

percent colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less; and

3. A dry value no more than 1 unit higher than the moist

value.

Rhodic Kanhapludults

HCDN. Other Kanhapludults.

Typic Kanhapludults

Paleudults

Key to Subgroups

HCEA. Paleudults that have one or both of the following:

1. Cracks within 125 cm of the mineral soil surface that

are 5 mm or more wide through a thickness of 30 cm or

more for some time in normal years and slickensides or

wedge-shaped aggregates in a layer 15 cm or more thick that

has its upper boundary within 125 cm of the mineral soil

surface; or
274 Keys to Soil Taxonomy

2. A linear extensibility of 6.0 cm or more between the

mineral soil surface and either a depth of 100 cm or a densic,

lithic, or paralithic contact, whichever is shallower.

Vertic Paleudults

HCEB. Other Paleudults that have a horizon 5 cm or more

thick, either below an Ap horizon or at a depth of 18 cm or

more from the mineral soil surface, whichever is deeper, that

has one or more of the following:

1. In 25 percent or more of each pedon, cementation by

organic matter and aluminum, with or without iron; or

2. Al plus 1

/2 Fe percentages (by ammonium oxalate)

totaling 0.25 or more, and half that amount or less in an

overlying horizon; or

3. An ODOE value of 0.12 or more, and a value half as

high or lower in an overlying horizon.

Spodic Paleudults

HCEC. Other Paleudults that have:

1. In one or more layers either within 75 cm of the mineral

soil surface or, if the chroma throughout the upper 75 cm

results from uncoated sand grains, within the upper 12.5 cm

of the argillic horizon, redox depletions with a color value,

moist, of 4 or more and chroma of 2 or less, accompanied by

redox concentrations, and also aquic conditions for some

time in normal years (or artificial drainage); and

2. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 cm or more; and

3. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Arenic Plinthaquic Paleudults

HCED. Other Paleudults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon that is 50 cm or more below the mineral

soil surface; and

2. In one or more layers either within 75 cm of the mineral

soil surface or, if the chroma throughout the upper 75 cm

results from uncoated sand grains, within the upper 12.5 cm

of the argillic horizon, redox depletions with a color value,

moist, of 4 or more and chroma of 2 or less, accompanied by

redox concentrations, and also aquic conditions for some

time in normal years (or artificial drainage).

Aquic Arenic Paleudults

HCEE. Other Paleudults that have anthraquic conditions.

Anthraquic Paleudults

HCEF. Other Paleudults that have both:

1. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface; and

2. In one or more layers either within 75 cm of the mineral

soil surface or, if the chroma throughout the upper 75 cm

results from uncoated sand grains, within the upper 12.5 cm

of the argillic horizon, redox depletions with a color value,

moist, of 4 or more and chroma of 2 or less, accompanied by

redox concentrations, and also aquic conditions for some

time in normal years (or artificial drainage).

Plinthaquic Paleudults

HCEG. Other Paleudults that have both:

1. Fragic soil properties:

a. In 30 percent or more of the volume of a layer 15 cm

or more thick that has its upper boundary within 100 cm

of the mineral soil surface; or

b. In 60 percent or more of the volume of a layer 15 cm

or more thick; and

2. In one or more layers within 75 cm of the mineral soil

surface, redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less, accompanied by redox

concentrations, and also aquic conditions for some time in

normal years (or artificial drainage).

Fragiaquic Paleudults

HCEH. Other Paleudults that have, in one or more layers

within 75 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less,

accompanied by redox concentrations and by aquic conditions

for some time in normal years (or artificial drainage).

Aquic Paleudults

HCEI. Other Paleludults that in normal years are saturated

with water in one or more layers within 100 cm of the mineral

soil surface for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Paleudults

HCEJ. Other Paleudults that have an argillic horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more

than 20 cm thick, each with an overlying eluvial horizon,

and above these horizons there are either:
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a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic

horizon); or

b. A combination of lamellae (that may or may not be

part of the argillic horizon) and one or more parts of the

argillic horizon 7.5 to 20 cm thick, each with an overlying

eluvial horizon.

Lamellic Paleudults

HCEK. Other Paleudults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 to 100 cm; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Arenic Plinthic Paleudults

HCEL. Other Paleudults that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or

throughout the entire argillic horizon if it is less than 75 cm

thick.

Psammentic Paleudults

HCEM. Other Paleudults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 100 cm or more; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Grossarenic Plinthic Paleudults

HCEN. Other Paleudults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Paleudults

HCEO. Other Paleudults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of

an argillic horizon at a depth of 50 to 100 cm; and

2. In all subhorizons in the upper 75 cm of the argillic

horizon or throughout the entire argillic horizon if it is less

than 75 cm thick, more than 50 percent colors that have all

of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less; and

c. A dry value no more than 1 unit higher than the moist

value.

Arenic Rhodic Paleudults

HCEP. Other Paleudults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 to 100 cm.

Arenic Paleudults

HCEQ. Other Paleudults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 100 cm or more.

Grossarenic Paleudults

HCER. Other Paleudults that have fragic soil properties:

1. In 30 percent or more of the volume of a layer 15 cm or

more thick that has its upper boundary within 100 cm of the

mineral soil surface; or

2. In 60 percent or more of the volume of a layer 15 cm or

more thick.

Fragic Paleudults

HCES. Other Paleudults that have, in all subhorizons in the

upper 75 cm of the argillic horizon or throughout the entire

argillic horizon if it is less than 75 cm thick, more than 50

percent colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less; and

3. A dry value no more than 1 unit higher than the moist

value.

Rhodic Paleudults

HCET. Other Paleudults.

Typic Paleudults

Plinthudults

Key to Subgroups

HCAA. All Plinthudults.

Typic Plinthudults

Rhodudults

Key to Subgroups

HCFA. Rhodudults that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Rhodudults

HCFB. Other Rhodudults that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or

throughout the entire argillic horizon if it is less than 75 cm

thick.

Psammentic Rhodudults
276 Keys to Soil Taxonomy

HCFC. Other Rhodudults.

Typic Rhodudults

Ustults

Key to Great Groups

HDA. Ustults that have one or more horizons within 150

cm of the mineral soil surface in which plinthite either forms

a continuous phase or constitutes one-half or more of the

volume.

Plinthustults, p. 279

HDB. Other Ustults that:

1. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

2. Have a kandic horizon; and

3. Within 150 cm of the mineral soil surface, either:

a. With increasing depth, do not have a clay decrease of

20 percent or more (relative) from the maximum clay

content; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction.

Kandiustults, p. 277

HDC. Other Ustults that have a kandic horizon.

Kanhaplustults, p. 278

HDD. Other Ustults that:

1. Do not have a densic, lithic, paralithic, or petroferric

contact within 150 cm of the mineral soil surface; and

2. Within 150 cm of the mineral soil surface, either:

a. With increasing depth, do not have a clay decrease of

20 percent or more (relative) from the maximum clay

content; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction.

Paleustults, p. 279

HDE. Other Ustults that have both:

1. An epipedon that has a color value, moist, of 3 or less

throughout; and

2. In all subhorizons in the upper 100 cm of the argillic

horizon or throughout the entire argillic horizon if it is less

than 100 cm thick, more than 50 percent colors that have all

of the following:

a. Hue of 2.5YR or redder; and

b. A value, moist, of 3 or less; and

c. A dry value no more than 1 unit higher than the moist

value.

Rhodustults, p. 279

HDF. Other Ustults.

Haplustults, p. 276

Haplustults

Key to Subgroups

HDFA. Haplustults that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haplustults

HDFB. Other Haplustults that have a petroferric contact

within 100 cm of the mineral soil surface.

Petroferric Haplustults

HDFC. Other Haplustults that have, in one or more layers

both within the upper 12.5 cm of the argillic horizon and within

75 cm of the mineral soil surface, redox depletions with a color

value, moist, of 4 or more and chroma of 2 or less,

accompanied by redox concentrations and by aquic conditions

for some time in normal years (or artificial drainage).

Aquic Haplustults

HDFD. Other Haplustults that have a sandy or sandy-skeletal

particle-size class throughout a layer extending from the

mineral soil surface to the top of an argillic horizon at a depth

of 50 cm or more below the mineral soil surface.

Arenic Haplustults

HDFE. Other Haplustults that:

1. Have, in one or more horizons within 75 cm of the

mineral soil surface, redox concentrations, a color value,

moist, of 4 or more, and hue that is 10YR or yellower and

becomes redder with increasing depth within 100 cm of the

mineral soil surface; and

2. In normal years are saturated with water in one or more

layers within 100 cm of the mineral soil surface for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Ombroaquic Haplustults

HDFF. Other Haplustults that have 5 percent or more (by
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volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Haplustults

HDFG. Other Haplustults that have a CEC (by 1N NH4

OAc

pH 7) of less than 24 cmol(+)/kg clay in 50 percent or more of

the entire argillic horizon if less than 100 cm thick or of its

upper 100 cm.

Kanhaplic Haplustults

HDFH. Other Haplustults.

Typic Haplustults

Kandiustults

Key to Subgroups

HDBA. Kandiustults that have an ECEC of 1.5 cmol(+)/kg

clay or less (sum of bases extracted with 1N NH4OAc pH 7,

plus 1N KCl-extractable Al) in one or more horizons within 150

cm of the mineral soil surface.

Acrustoxic Kandiustults

HDBB. Other Kandiustults that have, in one or more layers

within 75 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less,

accompanied by redox concentrations and by aquic conditions

for some time in normal years (or artificial drainage).

Aquic Kandiustults

HDBC. Other Kandiustults that have both:

1. A sandy or sandy-skeletal particle-size class throughout

a layer extending from the mineral soil surface to the top of a

kandic horizon at a depth of 50 cm or more; and

2. 5 percent or more (by volume) plinthite in one or more

horizons within 150 cm of the mineral soil surface.

Arenic Plinthic Kandiustults

HDBD. Other Kandiustults that have a sandy or sandyskeletal particle-size class throughout a layer extending from

the mineral soil surface to the top of a kandic horizon at a depth

of 50 cm or more.

Arenic Kandiustults

HDBE. Other Kandiustults that have both:

1. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface, a

fine-earth fraction with both a bulk density of 1.0 g/cm3

 or

less, measured at 33 kPa water retention, and Al plus 1/2 Fe

percentages (by ammonium oxalate) totaling more than 1.0;

and

2. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that is dry in some part for 135

or fewer of the cumulative days per year when the

temperature at a depth of 50 cm below the soil surface is

higher than 5 oC; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that is

dry in some or all parts for fewer than 120 cumulative

days per year when the temperature at a depth of 50 cm

below the soil surface is higher than 8 oC.

Udandic Kandiustults

HDBF. Other Kandiustults that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Kandiustults

HDBG. Other Kandiustults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kandiustults

HDBH. Other Kandiustults that, when neither irrigated nor

fallowed to store moisture, have either:

1. A thermic, mesic, or colder soil temperature regime and

a moisture control section that in normal years is dry in some

part for more than four-tenths of the cumulative days per

year when the soil temperature at a depth of 50 cm below the

soil surface is higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil temperature

regime and a moisture control section that in normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature at a

depth of 50 cm below the soil surface is higher than 5 oC.

Aridic Kandiustults

HDBI. Other Kandiustults that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for 135 or fewer of the cumulative days per year when

the temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil
278 Keys to Soil Taxonomy

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Udic Kandiustults

HDBJ. Other Kandiustults that have, in all subhorizons in the

upper 50 cm of the kandic horizon or throughout the entire

kandic horizon if it is less than 75 cm thick, more than 50

percent colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less; and

3. A dry value no more than 1 unit higher than the moist

value.

Rhodic Kandiustults

HDBK. Other Kandiustults.

Typic Kandiustults

Kanhaplustults

Key to Subgroups

HDCA. Kanhaplustults that have a lithic contact within 50 cm

of the mineral soil surface.

Lithic Kanhaplustults

HDCB. Other Kanhaplustults that have an ECEC of 1.5

cmol(+)/kg clay or less (sum of bases extracted with 1N

NH4

OAc pH 7, plus 1N KCl-extractable Al) in one or more

horizons within 150 cm of the mineral soil surface.

Acrustoxic Kanhaplustults

HDCC. Other Kanhaplustults that have, in one or more layers

within 75 cm of the mineral soil surface, redox depletions with

a color value, moist, of 4 or more and chroma of 2 or less,

accompanied by redox concentrations and by aquic conditions

for some time in normal years (or artificial drainage).

Aquic Kanhaplustults

HDCD. Other Kanhaplustults that have a sandy or sandyskeletal particle-size class throughout a layer extending from

the mineral soil surface to the top of a kandic horizon at a depth

of 50 to 100 cm.

Arenic Kanhaplustults

HDCE. Other Kanhaplustults that have both:

1. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface, a

fine-earth fraction with both a bulk density of 1.0 g/cm3

 or

less, measured at 33 kPa water retention, and Al plus 1/2 Fe

percentages (by ammonium oxalate) totaling more than 1.0;

and

2. When neither irrigated nor fallowed to store moisture,

either:

a. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in

some part for 135 or fewer of the cumulative days per

year when the temperature at a depth of 50 cm below the

soil surface is higher than 5 o

C; or

b. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the temperature at a depth

of 50 cm below the soil surface is higher than 8 oC.

Udandic Kanhaplustults

HDCF. Other Kanhaplustults that have, throughout one or

more horizons with a total thickness of 18 cm or more within

75 cm of the mineral soil surface, a fine-earth fraction with both

a bulk density of 1.0 g/cm3

 or less, measured at 33 kPa water

retention, and Al plus 1/2 Fe percentages (by ammonium

oxalate) totaling more than 1.0.

Andic Kanhaplustults

HDCG. Other Kanhaplustults that have 5 percent or more (by

volume) plinthite in one or more horizons within 150 cm of the

mineral soil surface.

Plinthic Kanhaplustults

HDCH. Other Kanhaplustults that:

1. Have, in one or more horizons within 75 cm of the

mineral soil surface, redox concentrations, a color value,

moist, of 4 or more, and hue that is 10YR or yellower and

becomes redder with increasing depth within 100 cm of the

mineral soil surface; and

2. In normal years are saturated with water in one or more

layers within 100 cm of the mineral soil surface for either or

both:

a. 20 or more consecutive days; or

b. 30 or more cumulative days.

Ombroaquic Kanhaplustults

HDCI. Other Kanhaplustults that, when neither irrigated nor

fallowed to store moisture, have either:

1. A thermic, mesic, or colder soil temperature regime and

a moisture control section that in normal years is dry in some

part for more than four-tenths of the cumulative days per

year when the soil temperature at a depth of 50 cm below the

soil surface is higher than 5 o

C; or
Ultisols 279

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2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years:

a. Is moist in some or all parts for fewer than 90

consecutive days per year when the temperature at a

depth of 50 cm below the soil surface is higher than 8 oC;

and

b. Is dry in some part for six-tenths or more of the

cumulative days per year when the soil temperature

at a depth of 50 cm below the soil surface is higher than

5 oC.

Aridic Kanhaplustults

HDCJ. Other Kanhaplustults that, when neither irrigated nor

fallowed to store moisture, have either:

1. A mesic or thermic soil temperature regime and a

moisture control section that in normal years is dry in some

part for 135 or fewer of the cumulative days per year when

the temperature at a depth of 50 cm below the soil surface is

higher than 5 o

C; or

2. A hyperthermic, isomesic, or warmer iso soil

temperature regime and a moisture control section that in

normal years is dry in some or all parts for fewer than 120

cumulative days per year when the temperature at a depth of

50 cm below the soil surface is higher than 8 oC.

Udic Kanhaplustults

HDCK. Other Kanhaplustults that have, in all subhorizons in

the upper 50 cm of the kandic horizon or throughout the entire

kandic horizon if it is less than 50 cm thick, more than 50

percent colors that have all of the following:

1. Hue of 2.5YR or redder; and

2. A value, moist, of 3 or less; and

3. A dry value no more than 1 unit higher than the moist

value.

Rhodic Kanhaplustults

HDCL. Other Kanhaplustults.

Typic Kanhaplustults

Paleustults

Key to Subgroups

HDDA. All Paleustults.

Typic Paleustults

Plinthustults

Key to Subgroups

HDAA. Plinthustults that have:

1. A densic, lithic, paralithic, or petroferric contact

within 150 cm of the mineral soil surface; or

2. Within 150 cm of the mineral soil surface, both:

a. With increasing depth, a clay decrease of 20

percent or more (relative) from the maximum clay

content; and

b. Less than 5 percent (by volume) skeletans on faces of

peds in the layer that has a 20 percent lower clay content

or, below that layer, a clay increase of less than 3 percent

(absolute) in the fine-earth fraction.

Haplic Plinthustults

HDAB. Other Plinthustults.

Typic Plinthustults

Rhodustults

Key to Subgroups

HDEA. Rhodustults that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Rhodustults

HDEB. Other Rhodustults that have a sandy particle-size class

throughout the upper 75 cm of the argillic horizon or throughout

the entire argillic horizon if it is less than 75 cm thick.

Psammentic Rhodustults

HDEC. Other Rhodustults.

Typic Rhodustults

Xerults

Key to Great Groups

HEA. Xerults that:

1. Do not have a densic, lithic, or paralithic contact

within 150 cm of the mineral soil surface; and

2. Within 150 cm of the mineral soil surface, either:

a. With increasing depth, do not have a clay decrease of

20 percent or more (relative) from the maximum clay

content; or

b. Have 5 percent or more (by volume) skeletans on

faces of peds or 5 percent or more (by volume) plinthite,

or both, in the layer that has a 20 percent lower clay

content and, below that layer, a clay increase of 3 percent

or more (absolute) in the fine-earth fraction.

Palexerults, p. 280

HEB. Other Xerults.

Haploxerults, p. 280
280 Keys to Soil Taxonomy

Haploxerults

Key to Subgroups

HEBA. Haploxerults that have both:

1. A lithic contact within 50 cm of the mineral soil surface;

and

2. In each pedon, a discontinuous argillic or kandic horizon

that is interrupted by ledges of bedrock.

Lithic Ruptic-Inceptic Haploxerults

HEBB. Other Haploxerults that have a lithic contact within 50

cm of the mineral soil surface.

Lithic Haploxerults

HEBC. Other Haploxerults that have, in one or more

subhorizons within the upper 25 cm of the argillic or kandic

horizon, redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less, accompanied by redox

concentrations and by aquic conditions for some time in normal

years (or artificial drainage).

Aquic Haploxerults

HEBD. Other Haploxerults that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk

density of 1.0 g/cm3

 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Haploxerults

HEBE. Other Haploxerults that have an argillic or kandic

horizon that:

1. Consists entirely of lamellae; or

2. Is a combination of two or more lamellae and one or

more subhorizons with a thickness of 7.5 to 20 cm, each

layer with an overlying eluvial horizon; or

3. Consists of one or more subhorizons that are more

than 20 cm thick, each with an overlying eluvial horizon,

andabove these horizons there are either:

a. Two or more lamellae with a combined thickness of 5

cm or more (that may or may not be part of the argillic or

kandic horizon); or

b. A combination of lamellae (that may or may

not be part of the argillic or kandic horizon) and

one or more parts of the argillic or kandic horizon

7.5 to 20 cm thick, each with an overlying eluvial

horizon.

Lamellic Haploxerults

HEBF. Other Haploxerults that have a sandy particle-size

class throughout the upper 75 cm of the argillic or kandic

horizon or throughout the entire horizon if it is less than 75 cm

thick.

Psammentic Haploxerults

HEBG. Other Haploxerults that have a sandy or sandyskeletal particle-size class throughout a layer extending from

the mineral soil surface to the top of an argillic or kandic

horizon at a depth of 50 to 100 cm.

Arenic Haploxerults

HEBH. Other Haploxerults that have a sandy or sandyskeletal particle-size class throughout a layer extending from

the mineral soil surface to the top of an argillic or kandic

horizon at a depth of 100 cm or more.

Grossarenic Haploxerults

HEBI. Other Haploxerults.

Typic Haploxerults

Palexerults

Key to Subgroups

HEAA. Palexerults that have both:

1. In one or more subhorizons within the upper 25 cm of

the argillic or kandic horizon, redox depletions with a color

value, moist, of 4 or more and chroma of 2 or less,

accompanied by redox concentrations, and also aquic

conditions for some time in normal years (or artificial

drainage); and

2. Throughout one or more horizons with a total thickness

of 18 cm or more within 75 cm of the mineral soil surface,

a fine-earth fraction with both a bulk density of 1.0 g/cm3

or less, measured at 33 kPa water retention, and Al plus

1

/2 Fe percentages (by ammonium oxalate) totaling more

than 1.0.

Aquandic Palexerults

HEAB. Other Palexerults that have, in one or more

subhorizons within the upper 25 cm of the argillic or kandic

horizon, redox depletions with a color value, moist, of 4 or

more and chroma of 2 or less, accompanied by redox

concentrations and by aquic conditions for some time in normal

years (or artificial drainage).

Aquic Palexerults

HEAC. Other Palexerults that have, throughout one or more

horizons with a total thickness of 18 cm or more within 75 cm

of the mineral soil surface, a fine-earth fraction with both a bulk
Ultisols 281

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density of 1.0 g/cm3 or less, measured at 33 kPa water retention,

and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling

more than 1.0.

Andic Palexerults

HEAD. Other Palexerults.

Typic Palexerults

283

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Key to Suborders

FA. Vertisols that have, in one or more horizons within 50 cm of

the mineral soil surface, aquic conditions for some time in normal

years (or artificial drainage) and one or both of the following:

1. In more than half of each pedon, either on faces of peds

or in the matrix if peds are absent, 50 percent or more

chroma of either:

a. 2 or less if redox concentrations are present; or

b. 1 or less; or

2. Enough active ferrous iron (Fe2+) to give a positive

reaction to alpha,alpha-dipyridyl at a time when the soil is

not being irrigated.

Aquerts, p. 283

FB. Other Vertisols that have a cryic soil temperature regime.

Cryerts, p. 287

FC. Other Vertisols that in normal years have both:

1. A thermic, mesic, or frigid soil temperature regime; and

2. If not irrigated during the year, cracks that remain both:

a. 5 mm or more wide, through a thickness of 25 cm or

more within 50 cm of the mineral soil surface, for 60 or

more consecutive days during the 90 days following the

summer solstice; and

b. Closed for 60 or more consecutive days during the 90

days following the winter solstice.

Xererts, p. 293

FD. Other Vertisols that, if not irrigated during the year, have

cracks in normal years that remain closed for less than 60

consecutive days during a period when the soil temperature at a

depth of 50 cm from the soil surface is higher than 8 o

C.

Torrerts, p. 287

FE. Other Vertisols that, if not irrigated during the year, have

cracks in normal years that are 5 mm or more wide, through a

thickness of 25 cm or more within 50 cm of the mineral soil

surface, for 90 or more cumulative days per year.

Usterts, p. 290

CHAPTER 16

Vertisols

FF. Other Vertisols.

Uderts, p. 289

Aquerts

Key to Great Groups

FAA. Aquerts that have within 100 cm of the mineral soil

surface either:

1. A sulfuric horizon; or

2. Sulfidic materials.

Sulfaquerts, p. 287

FAB. Aquerts that have a salic horizon that has its upper

boundary within 100 cm of the mineral soil surface.

Salaquerts, p. 286

FAC. Other Aquerts that have a duripan that has its upper

boundary within 100 cm of the mineral soil surface.

Duraquerts, p. 284

FAD. Other Aquerts that have a natric horizon or have an

exchangeable sodium percentage of 15 percent or more (or a

sodium adsorption ratio of 13 or more) within 100 cm of the

mineral soil surface.

Natraquerts, p. 286

FAE. Other Aquerts that have a calcic horizon that has its

upper boundary within 100 cm of the mineral soil surface.

Calciaquerts, p. 284

FAF. Other Aquerts that have, throughout one or more

horizons with a total thickness of 25 cm or more within 50 cm

of the mineral soil surface, both:

1. An electrical conductivity in the saturation extract of

less than 4.0 dS/m at 25 o

C; and

2. A pH value of 4.5 or less in 0.01 M CaCl2 (5.0 or less in

1:1 water).

Dystraquerts, p. 284

FAG. Other Aquerts that have episaturation.

Epiaquerts, p. 286
284 Keys to Soil Taxonomy

FAH. Other Aquerts.

Endoaquerts, p. 285

Calciaquerts

Key to Subgroups

FAEA. Calciaquerts that have, in one or more horizons

between either an Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and either a depth of

75 cm or the upper boundary of a duripan if shallower, 50

percent or more colors as follows:

1. Hue of 2.5Y or redder and either:

a. A color value, moist, of 6 or more and chroma of 3 or

more; or

b. A color value, moist, of 5 or less and chroma of 2 or

more; or

2. Hue of 5Y and chroma of 3 or more; or

3. Chroma of 2 or more and no redox concentrations.

Aeric Calciaquerts

FAEB. Other Calciaquerts.

Typic Calciaquerts

Duraquerts

Key to Subgroups

FACA. Duraquerts that, if not irrigated during the year, have

cracks in normal years that are 5 mm or more wide, through a

thickness of 25 cm or more within 50 cm of the mineral soil

surface, for 210 or more cumulative days per year.

Aridic Duraquerts

FACB. Other Duraquerts that have a thermic, mesic, or frigid

soil temperature regime and that, if not irrigated during the year,

have cracks in normal years that remain both:

1. 5 mm or more wide, through a thickness of 25 cm or

more within 50 cm of the mineral soil surface, for 60 or

more consecutive days during the 90 days following the

summer solstice; and

2. Closed for 60 or more consecutive days during the 90

days following the winter solstice.

Xeric Duraquerts

FACC. Other Duraquerts that, if not irrigated during the year,

have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 90 or more cumulative days per year.

Ustic Duraquerts

FACD. Other Duraquerts that have, in one or more horizons

between either an Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and either a depth of

75 cm or the upper boundary of the duripan if shallower, 50

percent or more colors as follows:

1. Hue of 2.5Y or redder and either:

a. A color value, moist, of 6 or more and chroma of 3 or

more; or

b. A color value, moist, of 5 or less and chroma of 2 or

more; or

2. Hue of 5Y and chroma of 3 or more; or

3. Chroma of 2 or more and no redox concentrations.

Aeric Duraquerts

FACE. Other Duraquerts that have, in one or more horizons

within 30 cm of the mineral soil surface, one or both of the

following in more than half of each pedon:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more.

Chromic Duraquerts

FACF. Other Duraquerts.

Typic Duraquerts

Dystraquerts

Key to Subgroups

FAFA. Dystraquerts that have, in one or more horizons within

100 cm of the mineral soil surface, jarosite concentrations and a

pH value of 4.0 or less (1:1 water, air-dried slowly in shade).

Sulfaqueptic Dystraquerts

FAFB. Other Dystraquerts that, if not irrigated during the

year, have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 210 or more cumulative days per year.

Aridic Dystraquerts

FAFC. Other Dystraquerts that, if not irrigated during the

year, have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 90 or more cumulative days per year.

Ustic Dystraquerts

FAFD. Other Dystraquerts that have, in one or more horizons

between either an Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and a depth of 75 cm,

50 percent or more colors as follows:
Vertisols 285

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1. Hue of 2.5Y or redder and either:

a. A color value, moist, of 6 or more and chroma of 3 or

more; or

b. A color value, moist, of 5 or less and chroma of 2 or

more; or

2. Hue of 5Y and chroma of 3 or more; or

3. Chroma of 2 or more and no redox concentrations.

Aeric Dystraquerts

FAFE. Other Dystraquerts that have a densic, lithic, or

paralithic contact within 100 cm of the mineral soil surface.

Leptic Dystraquerts

FAFF. Other Dystraquerts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Dystraquerts

FAFG. Other Dystraquerts that have, in one or more horizons

within 30 cm of the mineral soil surface, one or both of the

following in more than half of each pedon:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more.

Chromic Dystraquerts

FAFH. Other Dystraquerts.

Typic Dystraquerts

Endoaquerts

Key to Subgroups

FAHA. Endoaquerts that have, throughout a layer 15 cm or

more thick within 100 cm of the mineral soil surface, an

electrical conductivity of 15 dS/m or more (saturated paste) for

6 or more months in normal years.

Halic Endoaquerts

FAHB. Other Endoaquerts that have, in one or more horizons

within 100 cm of the mineral soil surface, an exchangeable

sodium percentage of 15 or more (or a sodium adsorption ratio

of 13 or more) for 6 or more months in normal years.

Sodic Endoaquerts

FAHC. Other Endoaquerts that, if not irrigated during the

year, have cracks in normal years that are 5 mm or more

wide, through a thickness of 25 cm or more within 50 cm of

the mineral soil surface, for 210 or more cumulative days per

year.

Aridic Endoaquerts

FAHD. Other Endoaquerts that have a thermic, mesic, or

frigid soil temperature regime and that, if not irrigated during

the year, have cracks in normal years that remain both:

1. 5 mm or more wide, through a thickness of 25 cm or

more within 50 cm of the mineral soil surface, for 60 or

more consecutive days during the 90 days following the

summer solstice; and

2. Closed for 60 or more consecutive days during the 90

days following the winter solstice.

Xeric Endoaquerts

FAHE. Other Endoaquerts that, if not irrigated during the

year, have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 90 or more cumulative days per year.

Ustic Endoaquerts

FAHF. Other Endoaquerts that have, in one or more horizons

between either an Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and a depth of 75 cm,

50 percent or more colors as follows:

1. Hue of 2.5Y or redder and either:

a. A color value, moist, of 6 or more and chroma of 3 or

more; or

b. A color value, moist, of 5 or less and chroma of 2 or

more; or

2. Hue of 5Y and chroma of 3 or more; or

3. Chroma of 2 or more and no redox concentrations.

Aeric Endoaquerts

FAHG. Other Endoaquerts that have a densic, lithic, or

paralithic contact within 100 cm of the mineral soil surface.

Leptic Endoaquerts

FAHH. Other Endoaquerts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Endoaquerts

FAHI. Other Endoaquerts that have, in one or more horizons

within 30 cm of the mineral soil surface, one or both of the

following in more than half of each pedon:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more.

Chromic Endoaquerts

FAGJ. Other Endoaquerts.

Typic Endoaquerts
286 Keys to Soil Taxonomy

Epiaquerts

Key to Subgroups

FAGA. Epiaquerts that have, throughout a layer 15 cm or

more thick within 100 cm of the mineral soil surface, an

electrical conductivity of 15 dS/m or more (saturated paste) for

6 or more months in normal years.

Halic Epiaquerts

FAGB. Other Epiaquerts that have, in one or more horizons

within 100 cm of the mineral soil surface, an exchangeable

sodium percentage of 15 or more (or a sodium adsorption ratio

of 13 or more) for 6 or more months in normal years.

Sodic Epiaquerts

FAGC. Other Epiaquerts that, if not irrigated during the year,

have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 210 or more cumulative days per year.

Aridic Epiaquerts

FAGD. Other Epiaquerts that have a thermic, mesic, or frigid

soil temperature regime and that, if not irrigated during the year,

have cracks in normal years that remain both:

1. 5 mm or more wide, through a thickness of 25 cm or

more within 50 cm of the mineral soil surface, for 60 or

more consecutive days during the 90 days following the

summer solstice; and

2. Closed for 60 or more consecutive days during the 90

days following the winter solstice.

Xeric Epiaquerts

FAGE. Other Epiaquerts that, if not irrigated during the year,

have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 90 or more cumulative days per year.

Ustic Epiaquerts

FAGF. Other Epiaquerts that have, in one or more horizons

between either an Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and a depth of 75 cm,

50 percent or more colors as follows:

1. Hue of 2.5Y or redder and either:

a. A color value, moist, of 6 or more and chroma of 3 or

more; or

b. A color value, moist, of 5 or less and chroma of 2 or

more; or

2. Hue of 5Y and chroma of 3 or more; or

3. Chroma of 2 or more and no redox concentrations.

Aeric Epiaquerts

FAGG. Other Epiaquerts that have a densic, lithic, or

paralithic contact within 100 cm of the mineral soil surface.

Leptic Epiaquerts

FAGH. Other Epiaquerts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Epiaquerts

FAGI. Other Epiaquerts that have, in one or more horizons

within 30 cm of the mineral soil surface, one or both of the

following in more than half of each pedon:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more.

Chromic Epiaquerts

FAGJ. Other Epiaquerts.

Typic Epiaquerts

Natraquerts

Key to Subgroups

FADA. All Natraquerts.

Typic Natraquerts

Salaquerts

Key to Subgroups

FABA. Salaquerts that, if not irrigated during the year, have

cracks in normal years that are 5 mm or more wide, through a

thickness of 25 cm or more within 50 cm of the mineral soil

surface, for 210 or more cumulative days per year.

Aridic Salaquerts

FABB. Other Salaquerts that, if not irrigated during the year,

have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 90 or more cumulative days per year.

Ustic Salaquerts

FABC. Other Salaquerts that have a densic, lithic, or paralithic

contact within 100 cm of the mineral soil surface.

Leptic Salaquerts

FABD. Other Salaquerts that have a layer 25 cm or more thick

that contains less than 27 percent clay in its fine-earth fraction

and has its upper boundary within 100 cm of the mineral soil

surface.

Entic Salaquerts

FABE. Other Salaquerts that have, in one or more horizons
Vertisols 287

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within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Salaquerts

FABF. Other Salaquerts.

Typic Salaquerts

Sulfaquerts

Key to Subgroups

FAAA. Sulfaquerts that have a salic horizon within 75 cm of

the mineral soil surface.

Salic Sulfaquerts

FAAB. Other Sulfaquerts that do not have a sulfuric horizon

within 100 cm of the mineral soil surface.

Sulfic Sulfaquerts

FAAC. Other Sulfaquerts.

Typic Sulfaquerts

Cryerts

Key to Great Groups

FBA. Cryerts that have 10 kg/m2 or more organic carbon

between the mineral soil surface and a depth of 50 cm.

Humicryerts, p. 287

FBB. Other Cryerts.

Haplocryerts, p. 287

Haplocryerts

Key to Subgroups

FBBA. Haplocryerts that have, in one or more horizons within

100 cm of the mineral soil surface, an exchangeable sodium

percentage of 15 or more (or a sodium adsorption ratio of 13 or

more) for 6 or more months in normal years.

Sodic Haplocryerts

FBBB. Other Haplocryerts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Haplocryerts

FBBC. Other Haplocryerts.

Typic Haplocryerts

Humicryerts

Key to Subgroups

FBAA. Humicryerts that have, in one or more horizons within

100 cm of the mineral soil surface, an exchangeable sodium

percentage of 15 or more (or a sodium adsorption ratio of 13 or

more) for 6 or more months in normal years.

Sodic Humicryerts

FBAB. Other Humicryerts.

Typic Humicryerts

Torrerts

Key to Great Groups

FDA. Torrerts that have a salic horizon that has its upper

boundary within 100 cm of the soil surface.

Salitorrerts, p. 288

FDB. Other Torrerts that have a gypsic horizon that has its

upper boundary within 100 cm of the soil surface.

Gypsitorrerts, p. 288

FDC. Other Torrerts that have a calcic or petrocalcic horizon

that has its upper boundary within 100 cm of the soil surface.

Calcitorrerts, p. 287

FDD. Other Torrerts.

Haplotorrerts, p. 288

Calcitorrerts

Key to Subgroups

FDCA. Calcitorrerts that have a petrocalcic horizon that has

its upper boundary within 100 cm of the soil surface.

Petrocalcic Calcitorrerts

FDCB. Other Calcitorrerts that have a densic, lithic, or

paralithic contact, or the upper boundary of a duripan, within

100 cm of the soil surface.

Leptic Calcitorrerts

FDCC. Other Calcitorrerts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth
288 Keys to Soil Taxonomy

fraction and has its upper boundary within 100 cm of the soil

surface.

Entic Calcitorrerts

FDCD. Other Calcitorrerts that have, in one or more horizons

within 30 cm of the soil surface, 50 percent or more colors as

follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Calcitorrerts

FDCE. Other Calcitorrerts.

Typic Calcitorrerts

Gypsitorrerts

Key to Subgroups

FDBA. Gypsitorrerts that have, in one or more horizons

within 30 cm of the soil surface, 50 percent or more colors as

follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Gypsitorrerts

FDBB. Other Gypsitorrerts.

Typic Gypsitorrerts

Haplotorrerts

Key to Subgroups

FDDA. Haplotorrerts that have, throughout a layer 15 cm or

more thick within 100 cm of the soil surface, an electrical

conductivity of 15 dS/m or more (saturated paste) for 6 or more

months in normal years.

Halic Haplotorrerts

FDDB. Other Haplotorrerts that have, in one or more horizons

within 100 cm of the soil surface, an exchangeable sodium

percentage of 15 or more (or a sodium adsorption ratio of 13 or

more) for 6 or more months in normal years.

Sodic Haplotorrerts

FDDC. Other Haplotorrerts that have a densic, lithic, or

paralithic contact, or the upper boundary of a duripan, within

100 cm of the soil surface.

Leptic Haplotorrerts

FDDD. Other Haplotorrerts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the soil

surface.

Entic Haplotorrerts

FDDE. Other Haplotorrerts that have, in one or more horizons

within 30 cm of the soil surface, 50 percent or more colors as

follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Haplotorrerts

FDDF. Other Haplotorrerts.

Typic Haplotorrerts

Salitorrerts

Key to Subgroups

FDAA. Salitorrerts that have, in one or more horizons within

100 cm of the soil surface, aquic conditions for some time in

normal years (or artificial drainage) and either:

1. Redoximorphic features; or

2. Enough active ferrous iron (Fe2+) to give a positive

reaction to alpha,alpha-dipyridyl at a time when the soil is

not being irrigated.

Aquic Salitorrerts

FDAB. Other Salitorrerts that have a densic, lithic, or

paralithic contact, or the upper boundary of a duripan or

petrocalcic horizon, within 100 cm of the soil surface.

Leptic Salitorrerts

FDAC. Other Salitorrerts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the soil

surface.

Entic Salitorrerts

FDAD. Other Salitorrerts that have, in one or more horizons

within 30 cm of the soil surface, 50 percent or more colors as

follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Salitorrerts

FDAE. Other Salitorrerts.

Typic Salitorrerts
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Uderts

Key to Great Groups

FFA. Uderts that have, throughout one or more horizons with

a total thickness of 25 cm or more within 50 cm of the mineral

soil surface, both:

1. An electrical conductivity in the saturation extract of

less than 4.0 dS/m at 25 oC; and

2. A pH value of 4.5 or less in 0.01 M CaCl2 (5.0 or less

in saturated paste).

Dystruderts, p. 289

FFB. Other Uderts.

Hapluderts, p. 289

Dystruderts

Key to Subgroups

FFAA. Dystruderts that have, in one or more horizons

within 100 cm of the mineral soil surface, aquic conditions

for some time in normal years (or artificial drainage) and

either:

1. Redoximorphic features; or

2. Enough active ferrous iron (Fe2+) to give a positive

reaction to alpha,alpha-dipyridyl at a time when the soil is

not being irrigated.

Aquic Dystruderts

FFAB. Other Dystruderts that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for either or both:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Dystruderts

FFAC. Other Dystruderts that have a densic, lithic, or

paralithic contact within 100 cm of the mineral soil surface.

Leptic Dystruderts

FFAD. Other Dystruderts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Dystruderts

FFAE. Other Dystruderts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Dystruderts

FFAF. Other Dystruderts.

Typic Dystruderts

Hapluderts

Key to Subgroups

FFBA. Hapluderts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Hapluderts

FFBB. Other Hapluderts that have, in one or more horizons

within 100 cm of the mineral soil surface, aquic conditions

for some time in normal years (or artificial drainage) and either:

1. Redoximorphic features; or

2. Enough active ferrous iron (Fe2+) to give a positive

reaction to alpha,alpha-dipyridyl at a time when the soil is

not being irrigated.

Aquic Hapluderts

FFBC. Other Hapluderts that are saturated with water in one

or more layers within 100 cm of the mineral soil surface in

normal years for:

1. 20 or more consecutive days; or

2. 30 or more cumulative days.

Oxyaquic Hapluderts

FFBD. Other Hapluderts that have a densic, lithic,

or paralithic contact within 100 cm of the mineral soil surface.

Leptic Hapluderts

FFBE. Other Hapluderts that have a layer 25 cm or more thick

that contains less than 27 percent clay in its fine-earth fraction

and has its upper boundary within 100 cm of the mineral soil

surface.

Entic Hapluderts

FFBF. Other Hapluderts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Hapluderts

FFBG. Other Hapluderts.

Typic Hapluderts
290 Keys to Soil Taxonomy

Usterts

Key to Great Groups

FEA. Usterts that have, throughout one or more horizons with

a total thickness of 25 cm or more within 50 cm of the mineral

soil surface, both:

1. An electrical conductivity in the saturation extract of

less than 4.0 dS/m at 25 oC; and

2. A pH value of 4.5 or less in 0.01 M CaCl2 (5.0 or less in

saturated paste).

Dystrusterts, p. 290

FEB. Other Usterts that have a salic horizon that has its upper

boundary within 100 cm of the mineral soil surface.

Salusterts, p. 292

FEC. Other Usterts that have a gypsic horizon that has its

upper boundary within 100 cm of the mineral soil surface.

Gypsiusterts, p. 291

FED. Other Usterts that have a calcic or petrocalcic horizon

that has its upper boundary within 100 cm of the mineral soil

surface.

Calciusterts, p. 290

FEE. Other Usterts.

Haplusterts, p. 291

Calciusterts

Key to Subgroups

FEDA. Calciusterts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Calciusterts

FEDB. Other Calciusterts that have, throughout a layer 15 cm

or more thick within 100 cm of the mineral soil surface, an

electrical conductivity of 15 dS/m or more (saturated paste) for

6 or more months in normal years.

Halic Calciusterts

FEDC. Other Calciusterts that have, in one or more horizons

within 100 cm of the mineral soil surface, an exchangeable

sodium percentage of 15 or more (or a sodium adsorption ratio

of 13 or more) for 6 or more months in normal years.

Sodic Calciusterts

FEDD. Other Calciusterts that have a petrocalcic horizon that

has its upper boundary within 100 cm of the mineral soil

surface.

Petrocalcic Calciusterts

FEDE. Other Calciusterts that, if not irrigated during the year,

have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 210 or more cumulative days per year.

Aridic Calciusterts

FEDF. Other Calciusterts that, if not irrigated during the year,

have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for less than 150 cumulative days per year.

Udic Calciusterts

FEDG. Other Calciusterts that have a densic, lithic, or

paralithic contact, or the upper boundary of a duripan, within

100 cm of the mineral soil surface.

Leptic Calciusterts

FEDH. Other Calciusterts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Calciusterts

FEDI. Other Calciusterts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Calciusterts

FEDJ. Other Calciusterts.

Typic Calciusterts

Dystrusterts

Key to Subgroups

FEAA. Dystrusterts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Dystrusterts

FEAB. Other Dystrusterts that have, in one or more horizons

within 100 cm of the mineral soil surface, aquic conditions

for some time in normal years (or artificial drainage) and either:

1. Redoximorphic features; or

2. Enough active ferrous iron (Fe2+) to give a positive

reaction to alpha,alpha-dipyridyl at a time when the soil is

not being irrigated.

Aquic Dystrusterts

FEAC. Other Dystrusterts that, if not irrigated during the year,
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have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 210 or more cumulative days per

year.

Aridic Dystrusterts

FEAD. Other Dystrusterts that, if not irrigated during the

year, have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for less than 150 cumulative days.

Udic Dystrusterts

FEAE. Other Dystrusterts that have a densic, lithic, or

paralithic contact, or the upper boundary of a duripan, within

100 cm of the mineral soil surface.

Leptic Dystrusterts

FEAF. Other Dystrusterts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Dystrusterts

FEAG. Other Dystrusterts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Dystrusterts

FEAH. Other Dystrusterts.

Typic Dystrusterts

Gypsiusterts

Key to Subgroups

FECA. Gypsiusterts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Gypsiusterts

FECB. Other Gypsiusterts that have, throughout a layer 15 cm

or more thick within 100 cm of the mineral soil surface, an

electrical conductivity of 15 dS/m or more (saturated paste) for

6 or more months in normal years.

Halic Gypsiusterts

FECC. Other Gypsiusterts that have, in one or more horizons

within 100 cm of the mineral soil surface, an exchangeable

sodium percentage of 15 or more (or a sodium adsorption ratio

of 13 or more) for 6 or more months in normal years.

Sodic Gypsiusterts

FECD. Other Gypsiusterts that, if not irrigated during the

year, have cracks in normal years that are 5 mm or more

wide, through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 210 or more cumulative days per year.

Aridic Gypsiusterts

FECE. Other Gypsiusterts that, if not irrigated during the

year, have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for less than 150 cumulative days per year.

Udic Gypsiusterts

FECF. Other Gypsiusterts that have a densic, lithic, or

paralithic contact, or the upper boundary of a duripan or

petrocalcic horizon, within 100 cm of the mineral soil surface.

Leptic Gypsiusterts

FECG. Other Gypsiusterts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Gypsiusterts

FECH. Other Gypsiusterts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Gypsiusterts

FECI. Other Gypsiusterts.

Typic Gypsiusterts

Haplusterts

Key to Subgroups

FEEA. Haplusterts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haplusterts

FEEB. Other Haplusterts that have, throughout a layer 15 cm

or more thick within 100 cm of the mineral soil surface, an

electrical conductivity of 15 dS/m or more (saturated paste) for

6 or more months in normal years.

Halic Haplusterts

FEEC. Other Haplusterts that have, in one or more horizons

within 100 cm of the mineral soil surface, an exchangeable

sodium percentage of 15 or more (or a sodium adsorption ratio

of 13 or more) for 6 or more months in normal years.

Sodic Haplusterts
292 Keys to Soil Taxonomy

FEED. Other Haplusterts that have a petrocalcic horizon that

has its upper boundary within 150 cm of the mineral soil

surface.

Petrocalcic Haplusterts

FEEE. Other Haplusterts that have a gypsic horizon that has

its upper boundary within 150 cm of the mineral soil surface.

Gypsic Haplusterts

FEEF. Other Haplusterts that have a calcic horizon that has its

upper boundary within 150 cm of the mineral soil surface.

Calcic Haplusterts

FEEG. Other Haplusterts that have both:

1. A densic, lithic, or paralithic contact within 100 cm of

the mineral soil surface; and

2. If not irrigated during the year, cracks in normal years

that are 5 mm or more wide, through a thickness of 25 cm or

more within 50 cm of the mineral soil surface, for 210 or

more cumulative days per year.

Aridic Leptic Haplusterts

FEEH. Other Haplusterts that, if not irrigated during the year,

have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 210 or more cumulative days per year.

Aridic Haplusterts

FEEI. Other Haplusterts that have both:

1. A densic, lithic, or paralithic contact within 100 cm of

the mineral soil surface; and

2. If not irrigated during the year, cracks in 6 or more out

of 10 years that are 5 mm or more wide, through a thickness

of 25 cm or more within 50 cm of the mineral soil surface,

for less than 150 cumulative days per year.

Leptic Udic Haplusterts

FEEJ. Other Haplusterts that have both:

1. A layer 25 cm or more thick that contains less than 27

percent clay in its fine-earth fraction and has its upper

boundary within 100 cm of the mineral soil surface; and

2. If not irrigated during the year, cracks in normal years

that are 5 mm or more wide, through a thickness of 25 cm or

more within 50 cm of the mineral soil surface, for less than

150 cumulative days per year.

Entic Udic Haplusterts

FEEK. Other Haplusterts that have both:

1. In one or more horizons within 30 cm of the mineral soil

surface, 50 percent or more colors as follows:

a. A color value, moist, of 4 or more; or

b. A color value, dry, of 6 or more; or

c. Chroma of 3 or more; and

2. If not irrigated during the year, cracks in normal years

that are 5 mm or more wide, through a thickness of 25 cm or

more within 50 cm of the mineral soil surface, for less than

150 cumulative days per year.

Chromic Udic Haplusterts

FEEL. Other Haplusterts that, if not irrigated during the

year, have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for less than 150 cumulative days per

year.

Udic Haplusterts

FEEM. Other Haplusterts that have a densic, lithic, or

paralithic contact, or the upper boundary of a duripan, within

100 cm of the mineral soil surface.

Leptic Haplusterts

FEEN. Other Haplusterts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Haplusterts

FEEO. Other Haplusterts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Haplusterts

FEEP. Other Haplusterts.

Typic Haplusterts

Salusterts

Key to Subgroups

FEBA. Salusterts that have a lithic contact within 50 cm of the

mineral soil surface.

Lithic Salusterts

FEBB. Other Salusterts that have, in one or more horizons

within 100 cm of the mineral soil surface, an exchangeable

sodium percentage of 15 or more (or a sodium adsorption ratio

of 13 or more) for 6 or more months in normal years.

Sodic Salusterts
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FEBC. Other Salusterts that have, in one or more horizons

within 100 cm of the mineral soil surface, aquic conditions for

some time in normal years (or artificial drainage) and either:

1. Redoximorphic features; or

2. Enough active ferrous iron (Fe2+) to give a positive

reaction to alpha,alpha-dipyridyl at a time when the soil is

not being irrigated.

Aquic Salusterts

FEBD. Other Salusterts that, if not irrigated during the

year, have cracks in normal years that are 5 mm or more wide,

through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 210 or more cumulative days per

year.

Aridic Salusterts

FEBE. Other Salusterts that have a densic, lithic, or paralithic

contact, or the upper boundary of a duripan or petrocalcic

horizon, within 100 cm of the mineral soil surface.

Leptic Salusterts

FEBF. Other Salusterts that have a layer 25 cm or more thick

that contains less than 27 percent clay in its fine-earth fraction

and has its upper boundary within 100 cm of the mineral soil

surface.

Entic Salusterts

FEBG. Other Salusterts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Salusterts

FEBH. Other Salusterts.

Typic Salusterts

Xererts

Key to Great Groups

FCA. Xererts that have a duripan that has its upper boundary

within 100 cm of the mineral soil surface.

Durixererts, p. 293

FCB. Other Xererts that have a calcic or petrocalcic horizon

that has its upper boundary within 100 cm of the mineral soil

surface.

Calcixererts, p. 293

FCC. Other Xererts.

Haploxererts, p. 294

Calcixererts

Key to Subgroups

FCBA. Calcixererts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Calcixererts

FCBB. Other Calcixererts that have a petrocalcic horizon that

has its upper boundary within 100 cm of the mineral soil

surface.

Petrocalcic Calcixererts

FCBC. Other Calcixererts that, if not irrigated during the

year, have cracks in normal years that remain 5 mm or more

wide, through a thickness of 25 cm or more within 50 cm of

the mineral soil surface, for 180 or more consecutive days.

Aridic Calcixererts

FCBD. Other Calcixererts that have a densic, lithic, or

paralithic contact within 100 cm of the mineral soil surface.

Leptic Calcixererts

FCBE. Other Calcixererts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Calcixererts

FCBF. Other Calcixererts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Calcixererts

FCBG. Other Calcixererts.

Typic Calcixererts

Durixererts

Key to Subgroups

FCAA. Durixererts that have, throughout a layer 15 cm or

more thick above the duripan, an electrical conductivity of 15

dS/m or more (saturated paste) for 6 or more months in normal

years.

Halic Durixererts
294

FCAB. Other Durixererts that have, in one or more horizons

above the duripan, an exchangeable sodium percentage of 15 or

more (or a sodium adsorption ratio of 13 or more) for 6 or more

months in normal years.

Sodic Durixererts

FCAC. Other Durixererts that have, in one or more horizons

above the duripan, aquic conditions for some time in normal

years (or artificial drainage) and either:

1. Redoximorphic features; or

2. Enough active ferrous iron (Fe2+) to give a positive

reaction to alpha,alpha-dipyridyl at a time when the soil is

not being irrigated.

Aquic Durixererts

FCAD. Other Durixererts that, if not irrigated during the year,

have cracks in normal years that remain 5 mm or more wide,

through a thickness of 25 cm or more above the duripan, for

180 or more consecutive days.

Aridic Durixererts

FCAE. Other Durixererts that, if not irrigated during the year,

have cracks in normal years that remain 5 mm or more wide,

through a thickness of 25 cm or more above the duripan, for

less than 90 consecutive days.

Udic Durixererts

FCAF. Other Durixererts that have a duripan that is not

indurated in any subhorizon.

Haplic Durixererts

FCAG. Other Durixererts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Durixererts

FCAH. Other Durixererts.

Typic Durixererts

Haploxererts

Key to Subgroups

FCCA. Haploxererts that have a lithic contact within 50 cm of

the mineral soil surface.

Lithic Haploxererts

FCCB. Other Haploxererts that have, throughout a layer 15

cm or more thick within 100 cm of the mineral soil surface, an

electrical conductivity of 15 dS/m or more (saturated paste) for

6 or more months in normal years.

Halic Haploxererts

FCCC. Other Haploxererts that have, in one or more horizons

within 100 cm of the mineral soil surface, an exchangeable

sodium percentage of 15 or more (or a sodium adsorption ratio

of 13 or more) for 6 or more months in normal years.

Sodic Haploxererts

FCCD. Other Haploxererts that, if not irrigated during the

year, have cracks in normal years that remain 5 mm or more

wide, through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for 180 or more consecutive days.

Aridic Haploxererts

FCCE. Other Haploxererts that have, in one or more horizons

within 100 cm of the mineral soil surface, aquic conditions for

some time in normal years (or artificial drainage) and either:

1. Redoximorphic features; or

2. Enough active ferrous iron (Fe2+) to give a positive

reaction to alpha,alpha-dipyridyl at a time when the soil is

not being irrigated.

Aquic Haploxererts

FCCF. Other Haploxererts that, if not irrigated during the

year, have cracks in normal years that remain 5 mm or more

wide, through a thickness of 25 cm or more within 50 cm of the

mineral soil surface, for less than 90 consecutive days.

Udic Haploxererts

FCCG. Other Haploxererts that have a densic, lithic, or

paralithic contact within 100 cm of the mineral soil surface.

Leptic Haploxererts

FCCH. Other Haploxererts that have a layer 25 cm or more

thick that contains less than 27 percent clay in its fine-earth

fraction and has its upper boundary within 100 cm of the

mineral soil surface.

Entic Haploxererts

FCCI. Other Haploxererts that have, in one or more horizons

within 30 cm of the mineral soil surface, 50 percent or more

colors as follows:

1. A color value, moist, of 4 or more; or

2. A color value, dry, of 6 or more; or

3. Chroma of 3 or more.

Chromic Haploxererts

FCCJ. Other Haploxererts.

Typic Haploxererts
295

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Families and series serve purposes that are largely pragmatic,

the series name is abstract, and the technical family name is

descriptive. In this chapter the descriptive terms used in the

names of families are defined, the control sections to which the

terms apply are given, and the criteria, including the taxa in

which they are used, are indicated.

Family Differentiae for Mineral Soils and

Mineral Layers of Some Organic Soils

The following differentiae are used to distinguish families of

mineral soils and the mineral layers of some organic soils

within a subgroup. The class names of these components are

used to form the family name. The components are listed and

defined in the same sequence in which the components appear

in the family names.

Particle-size classes

Mineralogy classes

Cation-exchange activity classes

Calcareous and reaction classes

Soil temperature classes

Soil depth classes

Rupture-resistance classes

Classes of coatings

Classes of cracks

Particle-Size Classes and Their Substitutes

Definition of Particle-Size Classes and Their Substitutes for

Mineral Soils

The first part of the family name is the name of either a

particle-size class or a substitute for a particle-size class. The

term particle-size class is used to characterize the grain-size

composition of the whole soil, including both the fine earth and

the rock and pararock fragments up to the size of a pedon, but it

excludes organic matter and salts more soluble than gypsum.

Substitutes for particle-size classes are used for soils that have

andic soil properties or a high content of volcanic glass,

pumice, or cinders.

The particle-size classes of this taxonomy represent a

compromise between conventional divisions in pedologic and

engineering classifications. Engineering classifications have set

the limit between sand and silt at a diameter of 74 microns,

while pedologic classifications have set it at either 50 or 20

microns. Engineering classifications have been based on grainsize percentages, by weight, in the soil fraction less than 74 mm

in diameter, while textural classes in pedologic classifications

have been based on percentages, by weight, in the fraction less

than 2.0 mm in diameter. In engineering classifications, the

separate very fine sand (diameter between 50 and 100 microns

or 0.05 and 0.1 mm) has been subdivided at 74 microns. In

defining the particle-size classes for this taxonomy, a similar

division has been made, but in a different way. Soil materials

that have a texture of fine sand or loamy fine sand normally

have an appreciable amount of very fine sand, most of which is

coarser than 74 microns. A silty sediment, such as loess, may

also contain an appreciable amount of very fine sand, most of

which is finer than 74 microns. Thus, in the design of particlesize classes for this taxonomy, the very fine sand has been

allowed to “float.” It is included with the sand if the texture

(fine-earth fraction) of a soil is sand, loamy fine sand, or

coarser. It is treated as silt, however, if the texture is very fine

sand, loamy very fine sand, sandy loam, silt loam, or finer.

No single set of particle-size classes seems adequate to serve

as family differentiae for all of the different kinds of soil. Thus,

this taxonomy provides 2 generalized and 11 more narrowly

defined classes, which permit relatively fine distinctions

between families of soils for which particle size is important,

while providing broader groupings for soils in which narrowly

defined particle-size classes would produce undesirable

separations. Thus, the term “clayey” is used for some soil

families to indicate a clay content of 35 percent (30 percent in

Vertisols) or more in specific horizons, while in other families

the more narrowly defined terms “fine” and “very-fine” indicate

that these horizons have a clay content either of 35 (30 percent

in Vertisols) to 60 percent or of 60 percent or more in their fineearth fraction. Fine earth refers to particles smaller than 2.0 mm

in diameter. Rock fragments are particles 2.0 mm or more in

diameter that are strongly cemented or more resistant to rupture

and include all particles with horizontal dimensions smaller

than the size of a pedon. Cemented fragments 2.0 mm or more

in diameter that are in a rupture-resistance class that is less

cemented than the strongly cemented class are referred to as

pararock fragments. Pararock fragments, like rock fragments,

include all particles between 2.0 mm and a horizontal

dimension smaller than the size of a pedon. Most pararock

fragments are broken into fragments 2.0 mm or less in diameter

during the preparation of samples for particle-size analysis in

CHAPTER 17

Family and Series Differentiae and Names
296 Keys to Soil Taxonomy

the laboratory. Therefore, pararock fragments are generally

included with the fine earth in the particle-size classes, although

cinders, pumice, and pumicelike fragments are treated as

fragments in the substitutes for classes, regardless of their

rupture-resistance class.

Substitutes for particle-size classes are used for soils that

have andic soil properties or a high content of volcanic glass,

pumice, or cinders. These materials cannot be readily dispersed,

and the results of dispersion vary. Consequently, normal

particle-size classes do not adequately characterize these

components. Substitutes for particle-size class names are used

for those parts of soils that have andic soil properties or a high

amount of volcanic glass, pumice, or cinders, as is the case with

Andisols and many Andic and Vitrandic subgroups of other soil

orders. Some Spodosols, whether identified in Andic subgroups

or not, have andic soil properties in some horizons within the

particle-size control section, and particle-size substitute class

names are used for these horizons.

Neither a particle-size class name nor a substitute for a

particle-size class name is used for Psamments, Psammaquents,

and Psammentic subgroups that are in a sandy particle-size

class. These taxa have, by definition, either a sandy particle-size

class or an ashy substitute class. The sandy particle-size class is

considered redundant in the family name. The ashy substitute

class, however, is named, if appropriate in these taxa.

Particle-size class names are applied, although with

reservations, to spodic horizons and other horizons that do not

have andic soil properties but contain significant amounts of

allophane, imogolite, ferrihydrite, or aluminum-humus

complexes. The isotic mineralogy class (defined below) is

helpful in identifying these particle-size classes.

In general, the weighted average particle-size class of the

whole particle-size control section (defined below) determines

what particle-size class name is used as a component of the

family name.

Strongly Contrasting Particle-Size Classes

If the particle-size control section consists of two parts with

strongly contrasting particle-size or substitute classes (listed

below), if both parts are 12.5 cm or more thick (including parts

not in the control section), and if the transition zone between

them is less than 12.5 cm thick, both class names are used. For

example, the family particle-size class is sandy over clayey if all

of the following criteria are met: the soil meets criterion D

(listed below) under the control section for particle-size classes

or their substitutes; any Ap horizon is less than 30 cm thick; the

weighted average particle-size class of the upper 30 cm of the

soil is sandy; the weighted average of the lower part is clayey;

and the transition zone is less than 12.5 cm thick. If a substitute

name applies to one or more parts of the particle-size control

section and the parts are not strongly contrasting classes, the

name of the thickest part (cumulative) is used as the soil family

name.

Aniso Class

If the particle-size control section includes more than one

pair of the strongly contrasting classes, listed below, then the

soil is assigned to an aniso class named for the pair of adjacent

classes that contrast most strongly. The aniso class is considered

part of the particle-size class name and is set off by commas

after the particle-size name. An example is a sandy over clayey,

aniso, mixed, active, mesic Aridic Haplustoll.

Generalized Particle-Size Classes

Two generalized particle-size classes, loamy and clayey, are

used for shallow classes (defined below) and for soils in Arenic,

Grossarenic, and Lithic subgroups. The clayey class is used for

all strongly contrasting particle-size classes with more than 35

percent clay (30 percent in Vertisols). The loamy particle-size

class is used for contrasting classes, where appropriate, to

characterize the lower part of the particle-size control section.

The generalized classes, where appropriate, are also used for all

strongly contrasting particle-size classes that include a

substitute class. For example, loamy over pumiceous or cindery

(not fine-loamy over pumiceous or cindery) is used.

Six generalized classes, defined later in this chapter, are used

for Terric subgroups of Histosols and Histels.

Control Section for Particle-Size Classes or Their

Substitutes in Mineral Soils

The particle-size and substitute class names listed below are

applied to certain horizons, or to the soil materials within

specific depth limits, that have been designated as the particlesize control section. The lower boundary of the control section

may be at a specified depth (in centimeters) below the mineral

soil surface or below the upper boundary of an organic layer

with andic soil properties, or it may be at the upper boundary of

a root-limiting layer. Unless otherwise indicated, the following

are considered root-limiting layers in this chapter: a duripan; a

fragipan; petrocalcic, petrogypsic, and placic horizons;

continuous ortstein; and densic, lithic, paralithic, and petroferric

contacts. The following list of particle-size control sections for

particular kinds of mineral soils is arranged as a key. This key,

like other keys in this taxonomy, is designed in such a way that

the reader makes the correct classification by going through the

key systematically, starting at the beginning and eliminating one

by one all classes that include criteria that do not fit the soil in

question. The soil belongs to the first class for which it meets

all of the criteria listed. The upper boundary of an argillic,

natric, or kandic horizon is used in the following key. This

boundary is not always obvious. If one of these horizons is

present but the upper boundary is irregular or broken, as in an

A/B or B/A horizon, the depth at which half or more of the

volume has the fabric of an argillic, natric, or kandic horizon

should be considered the upper boundary.
Family and Series Differentiae and Names 297

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Key to the Control Section for Particle-Size Classes or Their

Substitutes in Mineral Soils

A. For mineral soils that have a root-limiting layer (listed

above) within 36 cm of the mineral soil surface or below the

upper boundary of organic soil materials with andic soil

properties, whichever is shallower: From the mineral soil

surface or the upper boundary of the organic soil materials with

andic soil properties, whichever is shallower, to the rootlimiting layer; or

B. For Andisols: Between either the mineral soil surface or

the upper boundary of an organic layer with andic soil

properties, whichever is shallower, and the shallower of the

following: (a) a depth 100 cm below the starting point or (b) a

root-limiting layer; or

C. For those Alfisols, Ultisols, and great groups of Aridisols

and Mollisols, excluding soils in Lamellic subgroups, that have

an argillic, kandic, or natric horizon that has its upper boundary

within 100 cm of the mineral soil surface and its lower

boundary at a depth of 25 cm or more below the mineral soil

surface or that are in a Grossarenic or Arenic subgroup, use 1

through 4 below. For other soils, go to D below.

1. Strongly contrasting particle-size classes (defined and

listed later) within or below the argillic, kandic, or natric

horizon and within 100 cm of the mineral soil surface: The

upper 50 cm of the argillic, kandic, or natric horizon or to a

depth of 100 cm, whichever is deeper, but not below the

upper boundary of a root-limiting layer; or

2. All parts of the argillic, kandic, or natric horizon in or

below a fragipan: Between a depth of 25 cm from the

mineral soil surface and the top of the fragipan; or

3. A fragipan at a depth of less than 50 cm below the top of

the argillic, kandic, or natric horizon: Between the upper

boundary of the argillic, kandic, or natric horizon and the top

the fragipan; or

4. Other soils that meet C above: Either the whole argillic,

kandic, or natric horizon if 50 cm or less thick or the upper

50 cm of the horizon if more than 50 cm thick.

D. For those Alfisols, Ultisols, and great groups of Aridisols

and Mollisols that are in a Lamellic subgroup or have an

argillic, kandic, or natric horizon that has its upper boundary at

a depth of 100 cm or more from the mineral surface and that are

not in a Grossarenic or Arenic subgroup: Between the lower

boundary of an Ap horizon or a depth of 25 cm from the

mineral soil surface, whichever is deeper, and 100 cm below the

mineral soil surface or a root-limiting layer, whichever is

shallower; or

E. For other soils that have an argillic or natric horizon that

has its lower boundary at a depth of less than 25 cm from the

mineral surface: Between the upper boundary of the argillic

or natric horizon and a depth of 100 cm below the mineral

soil surface or a root-limiting layer, whichever is shallower;

or

F. All other mineral soils: Between the lower boundary of an

Ap horizon or a depth of 25 cm below the mineral soil surface,

whichever is deeper, and the shallower of the following: (a) a

depth of 100 cm below the mineral soil surface or (b) a rootlimiting layer.

Key to the Particle-Size and Substitute Classes of Mineral

Soils

This key, like other keys in this taxonomy, is designed in

such a way that the reader makes the correct classification by

going through the key systematically, starting at the beginning

and eliminating one by one all classes that include criteria that

do not fit the soil or layer in question. The class or substitute

name for each layer within the control section must be

determined from the key. If any two layers meet the criteria for

strongly contrasting particle-size classes (listed below), the soil

is named for that strongly contrasting class. If more than one

pair meets the criteria for strongly contrasting classes, the soil is

also in an aniso class named for the pair of adjacent classes that

contrast most strongly. If the soil has none of the strongly

contrasting classes, the weighted average soil materials within

the particle-size control section generally determine the class.

Exceptions are soils that are not strongly contrasting and that

have a substitute class name for one or more parts of the control

section. In these soils the class or substitute name of the thickest

(cumulative) part within the control section is used to determine

the family name.

A. Mineral soils that have, in the thickest part of the control

section (if the control section is not in one of the strongly

contrasting particle-size classes listed below), or in a part of the

control section that qualifies as an element in one of the

strongly contrasting particle-size classes listed below, or

throughout the control section, a fine-earth component

(including associated medium and finer pores) of less than 10

percent of the total volume and that meet one of the following

sets of substitute class criteria:

1. Have, in the whole soil, more than 60 percent (by

weight) volcanic ash, cinders, lapilli, pumice, and

pumicelike1

 fragments and, in the fraction coarser than 2.0

mm, two-thirds or more (by volume) pumice and/or

pumicelike fragments.

Pumiceous

or

2. Have, in the whole soil, more than 60 percent (by

weight) volcanic ash, cinders, lapilli, pumice, and

pumicelike fragments and, in the fraction coarser than 2.0

1 Pumicelike—vesicular pyroclastic materials other than pumice that have an apparent

specific gravity (including vesicles) of less than 1.0 g/cm3

.
298 Keys to Soil Taxonomy

mm, less than two-thirds (by volume) pumice and

pumicelike fragments.

Cindery

or

3. Other mineral soils that have a fine-earth component of

less than 10 percent (including associated medium and finer

pores) of the total volume.

Fragmental

or

B. Other mineral soils that have a fine-earth component of 10

percent or more (including associated medium and finer pores)

of the total volume and meet, in the thickest part of the control

section (if the control section is not in one of the strongly

contrasting particle-size classes listed below), or in a part of the

control section that qualifies as an element in one of the

strongly contrasting particle-size classes listed below, or

throughout the control section, one of the following sets of

substitute class criteria:

1. They:

a. Have andic soil properties and have a water

content at 1500 kPa tension of less than 30 percent

on undried samples and less than 12 percent on dried

samples; or

b. Do not have andic soil properties, have 30 percent or

more of the fine-earth fraction in the 0.02 to 2.0 mm

fraction, and have a volcanic class content (by grain

count) of 30 percent or more in the 0.02 to 2.0 mm

fraction; and

c. Have one of the following;

(1) A total of 35 percent or more (by volume) rock

and pararock fragments, of which two-thirds or more

(by volume) is pumice or pumicelike fragments.

Ashy-pumiceous

or

(2) 35 percent or more (by volume) rock fragments.

Ashy-skeletal

or

(3) Less than 35 percent (by volume) rock fragments.

Ashy

or

2. Have a fine-earth fraction that has andic soil properties

and that has a water content at 1500 kPa tension of less than

100 percent on undried samples; and

a. Have a total of 35 percent or more (by volume) rock

and pararock fragments, of which two-thirds or more (by

volume) is pumice or pumicelike fragments.

Medial-pumiceous

or

b. Have 35 percent or more (by volume) rock fragments.

Medial-skeletal

or

c. Have less than 35 percent (by volume) rock

fragments.

Medial

or

3. Have a fine-earth fraction that has andic soil properties

and that has a water content at 1500 kPa tension of 100

percent or more on undried samples; and

a. Have a total of 35 percent or more (by volume) rock

and pararock fragments, of which two-thirds or more (by

volume) is pumice or pumicelike fragments.

Hydrous-pumiceous

or

b. Have 35 percent or more (by volume) rock fragments.

Hydrous-skeletal

or

c. Have less than 35 percent (by volume) rock fragments.

Hydrous

or

Note: In the following classes, “clay” excludes clay-size

carbonates. Carbonates of clay size are treated as silt. If the

ratio of percent water retained at 1500 kPa tension to the

percentage of measured clay is 0.25 or less or 0.6 or more in

half or more of the particle-size control section or part of the

particle-size control section in strongly contrasting classes, then

the percentage of clay is estimated by the following formula:

Clay % = 2.5(% water retained at 1500 kPa tension - % organic

carbon).

C. Other mineral soils that, in the thickest part of the control

section (if part of the control section has a substitute for

particle-size class and is not in one of the strongly contrasting

particle-size classes listed below), or in a part of the control

section that qualifies as an element in one of the strongly

contrasting particle-size classes listed below, or throughout the

control section, meet one of the following sets of particle-size

class criteria:

1. Have 35 percent or more (by volume) rock fragments

and a fine-earth fraction with a texture of sand or loamy
Family and Series Differentiae and Names 299

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sand, including less than 50 percent (by weight) very fine

sand.

Sandy-skeletal

or

2. Have 35 percent or more (by volume) rock fragments

and less than 35 percent (by weight) clay.

Loamy-skeletal

or

3. Have 35 percent or more (by volume) rock fragments.

Clayey-skeletal

or

4. Have a texture of sand or loamy sand, including less

than 50 percent (by weight) very fine sand in the fine-earth

fraction.

Sandy

or

5. Have a texture of loamy very fine sand, very fine sand,

or finer, including less than 35 percent (by weight) clay in

the fine-earth fraction (excluding Vertisols), and are in a

shallow family (defined below) or in a Lithic, Arenic, or

Grossarenic subgroup, or the layer is an element in a

strongly contrasting particle-size class (listed below) and the

layer is the lower element or the other element is a substitute

for particle-size class.

Loamy

or

6. Have, in the fraction less than 75 mm in diameter, 15

percent or more (by weight) particles with diameters of 0.1

to 75 mm (fine sand or coarser, including rock fragments up

to 7.5 cm in diameter) and, in the fine-earth fraction, less

than 18 percent (by weight) clay.

Coarse-loamy

or

7. Have, in the fraction less than 75 mm in diameter, 15

percent or more (by weight) particles with diameters of 0.1

to 75 mm (fine sand or coarser, including rock fragments up

to 7.5 cm in diameter) and 18 to 35 percent (by weight) clay

(Vertisols are excluded).

Fine-loamy

or

8. Have, in the fraction less than 75 mm in diameter, less

than 15 percent (by weight) particles with diameters of 0.1 to

75 mm (fine sand or coarser, including rock fragments up to

7.5 cm in diameter) and, in the fine-earth fraction, less than

18 percent (by weight) clay.

Coarse-silty

or

9. Have, in the fraction less than 75 mm in diameter, less

than 15 percent (by weight) particles with diameters of 0.1 to

75 mm (fine sand or coarser, including rock fragments up to

7.5 cm in diameter) and, in the fine-earth fraction, 18 to 35

percent (by weight) clay (Vertisols are excluded).

Fine-silty

or

10. Have 35 percent or more (by weight) clay (more

than 30 percent in Vertisols) and are in a shallow family

(defined below) or in a Lithic, Arenic, or Grossarenic

subgroup, or the layer is an element in a strongly contrasting

particle-size class (listed below).

Clayey

or

11. Have (by weighted average) less than 60 percent (by

weight) clay in the fine-earth fraction.

Fine

or

12. Have 60 percent or more clay.

Very-fine

Strongly Contrasting Particle-Size Classes

The purpose of strongly contrasting particle-size classes is to

identify changes in pore-size distribution or composition that

are not identified in higher soil categories and that seriously

affect the movement and retention of water and/or nutrients.

The following particle-size or substitute classes are

considered strongly contrasting if both parts are 12.5 cm or

more thick (including parts not in the particle-size control

section; however, substitute class names are used only if the soil

materials to which they apply extend 10 cm or more into the

upper part of the particle-size control section) and if the

transition zone between the two parts of the particle-size control

section is less than 12.5 cm thick.

Some classes, such as sandy and sandy-skeletal, have been

combined in the following list. In those cases the combined

name is used as the family class if part of the control section

meets the criteria for either class.

1. Ashy over clayey

2. Ashy over clayey-skeletal

3. Ashy over loamy-skeletal

4. Ashy over loamy

5. Ashy over medial-skeletal

6. Ashy over medial (if the water content at 1500 kPa

tension in dried samples of the fine-earth fraction is 10

percent or less for the ashy materials and 15 percent or

more for the medial materials)
300 Keys to Soil Taxonomy

7. Ashy over pumiceous or cindery

8. Ashy over sandy or sandy-skeletal

9. Ashy-skeletal over fragmental or cindery (if the volume of

the fine-earth fraction is 35 percent or more [absolute]

greater in the ashy-skeletal part than in the fragmental or

cindery part)

10. Ashy-skeletal over loamy-skeletal

11. Ashy-skeletal over sandy or sandy-skeletal

12. Cindery over loamy

13. Cindery over medial-skeletal

14. Cindery over medial

15. Clayey over fragmental

16. Clayey over loamy (if there is an absolute difference of 25

percent or more between clay percentages of the fineearth fraction in the two parts of the control section)

17. Clayey over loamy-skeletal (if there is an absolute

difference of 25 percent or more between clay

percentages of the fine-earth fraction in the two parts of

the control section)

18. Clayey over sandy or sandy-skeletal

19. Clayey-skeletal over sandy or sandy-skeletal

20. Coarse-loamy over clayey

21. Coarse-loamy over fragmental

22. Coarse-loamy over sandy or sandy-skeletal (if the coarseloamy material contains less than 50 percent fine sand or

coarser sand)

23. Coarse-silty over clayey

24. Coarse-silty over sandy or sandy-skeletal

25. Fine-loamy over clayey (if there is an absolute difference

of 25 percent or more between clay percentages of the

fine-earth fraction in the two parts of the control section)

26. Fine-loamy over fragmental

27. Fine-loamy over sandy or sandy-skeletal

28. Fine-silty over clayey (if there is an absolute difference of

25 percent or more between clay percentages of the fineearth fraction in the two parts of the control section)

29. Fine-silty over fragmental

30. Fine-silty over sandy or sandy-skeletal

31. Hydrous over clayey-skeletal

32. Hydrous over clayey

33. Hydrous over fragmental

34. Hydrous over loamy-skeletal

35. Hydrous over loamy

36. Hydrous over sandy or sandy-skeletal

37. Loamy over ashy or ashy-pumiceous

38. Loamy over sandy or sandy-skeletal (if the loamy material

contains less than 50 percent fine sand or coarser sand)

39. Loamy over pumiceous or cindery

40. Loamy-skeletal over cindery (if the volume of the fineearth fraction is 35 percent or more [absolute] greater in

the loamy-skeletal part than in the cindery part)

41. Loamy-skeletal over clayey (if there is an absolute

difference of 25 percent or more between clay

percentages of the fine-earth fraction in the two parts of

the control section)

42. Loamy-skeletal over fragmental (if the volume of the fineearth fraction is 35 percent or more [absolute] greater in

the loamy-skeletal part than in the fragmental part)

43. Loamy-skeletal over sandy or sandy-skeletal (if the loamy

material has less than 50 percent fine sand or coarser sand)

44. Medial over ashy (if the water content at 1500 kPa tension

in dried samples of the fine-earth fraction is 15 percent or

more for the medial materials and 10 percent or less for

the ashy materials)

45. Medial over ashy-pumiceous or ashy-skeletal (if the water

content at 1500 kPa tension in dried samples of the fineearth fraction is 15 percent or more for the medial

materials and 10 percent or less for the ashy part)

46. Medial over clayey-skeletal

47. Medial over clayey

48. Medial over fragmental

49. Medial over hydrous (if the water content at 1500 kPa

tension in undried samples of the fine-earth fraction is 75

percent or less for the medial materials)

50. Medial over loamy-skeletal

51. Medial over loamy

52. Medial over pumiceous or cindery

53. Medial over sandy or sandy-skeletal

54. Medial-skeletal over fragmental or cindery (if the volume

of the fine-earth fraction is 35 percent or more [absolute]

greater in the medial-skeletal part than the fragmental or

cindery part)

55. Medial-skeletal over loamy-skeletal

56. Medial-skeletal over sandy or sandy-skeletal
Family and Series Differentiae and Names 301

F

A

M

57. Pumiceous or ashy-pumiceous over loamy

58. Pumiceous or ashy-pumiceous over loamy-skelatal

59. Pumiceous or ashy-pumiceous over medial-skeletal

60. Pumiceous or ashy-pumiceous over medial

61. Pumiceous or ashy-pumiceous over sandy or sandyskeletal

62. Sandy over clayey

63. Sandy over loamy (if the loamy material contains less

than 50 percent fine sand or coarser sand)

64. Sandy-skeletal over loamy (if the loamy material contains

less than 50 percent fine sand or coarser sand)

Mineralogy Classes

The mineralogy of soils is known to be useful in making

predictions about soil behavior and responses to management.

Some mineralogy classes occur or are important only in certain

taxa or particle-size classes, and others are important in all

particle-size classes. The following key to mineralogy classes is

designed to make those distinctions.

Control Section for Mineralogy Classes

The control section for mineralogy classes is the same as that

defined for the particle-size classes and their substitutes.

Key to Mineralogy Classes

This key, like other keys in this taxonomy, is designed in

such a way that the reader makes the correct classification by

going through the key systematically, starting at the beginning

and eliminating one by one any classes that include criteria that

do not fit the soil in question. The soil belongs to the first class

for which it meets all of the required criteria. The user should

first check the criteria in section A and, if the soil in question

does not meet the criteria listed there, proceed on to sections B,

C, D, and E, until the soil meets the criteria listed. All criteria

are based on a weighted average.

For soils with strongly contrasting particle-size classes, the

mineralogy for both named particle-size classes or substitutes

are given, unless they are the same. Examples are an ashy over

clayey, mixed (if both the ashy and clayey parts are mixed),

superactive, mesic Typic Vitraquand and a clayey over sandy

or sandy-skeletal, smectitic over mixed, thermic Vertic

Haplustept.

A. Oxisols and “kandi” and “kanhap” great groups of Alfisols

and Ultisols that in the mineralogy control section have:

1. More than 40 percent (by weight) iron oxide as Fe2

O3

(more than 28 percent Fe), by dithionite citrate, in the fineearth fraction.

Ferritic

or

2. More than 40 percent (by weight) gibbsite in the fineearth fraction.

Gibbsitic

or

3. Both:

a. 18 to 40 percent (by weight) iron oxide as Fe2

O3

(12.6 to 28 percent Fe), by dithionite citrate, in the fineearth fraction; and

b. 18 to 40 percent (by weight) gibbsite in the fine-earth

fraction.

Sesquic

or

4. 18 to 40 percent (by weight) iron oxide as Fe2

O3 (12.6

to 28 percent Fe), by dithionite citrate, in the fine-earth

fraction.

Ferruginous

or

5. 18 to 40 percent (by weight) gibbsite in the fine-earth

fraction.

Allitic

or

6. More than 50 percent (by weight) kaolinite plus

halloysite, dickite, nacrite, and other 1:1 or nonexpanding

2:1 layer minerals and gibbsite and less than 10 percent (by

weight) smectite in the fraction less than 0.002 mm in size;

and more kaolinite than halloysite.

Kaolinitic

or

7. More than 50 percent (by weight) halloysite plus

kaolinite and allophane and less than 10 percent (by weight)

smectite in the fraction less than 0.002 mm in size.

Halloysitic

or

8. All other properties in this category.

Mixed

or

B. Other soil layers or horizons, in the mineralogy control

section, that have a substitute class that replaces the particlesize class, other than fragmental, and that:

1. Have a sum of 8 times the Si (percent by weight

extracted by ammonium oxalate from the fine-earth fraction)

plus 2 times the Fe (percent by weight extracted by

ammonium oxalate from the fine-earth fraction) of 5 or

more, and 8 times the Si is more than 2 times the Fe.

Amorphic

or
302 Keys to Soil Taxonomy

2. Other soils that have a sum of 8 times the Si

(percent by weight extracted by ammonium oxalate from the

fine-earth fraction) plus 2 times the Fe (percent by weight

extracted by ammonium oxalate from the fine-earth fraction)

of 5 or more.

Ferrihydritic

or

3. Other soils that have 30 percent or more (by grain count)

volcanic glass in the 0.02 to 2.0 mm fraction.

Glassy

or

4. All other soils that have a substitute class.

Mixed

or

C. Other mineral soil layers or horizons, in the mineralogy

control section, in all other mineral soil orders and in Terric

subgroups of Histosols and Histels that have:

1. Any particle-size class and more than 40 percent (by

weight) carbonates (expressed as CaCO3

) plus gypsum, with

gypsum constituting more than 35 percent of the total weight

of carbonates plus gypsum, either in the fine-earth fraction

or in the fraction less than 20 mm in size, whichever has a

higher percentage of carbonates plus gypsum.

Gypsic

or

2. Any particle-size class and more than 40 percent (by

weight) carbonates (expressed as CaCO3

) plus gypsum,

either in the fine-earth fraction or in the fraction less than 20

mm in size, whichever has a higher percentage of carbonates

plus gypsum.

Carbonatic

or

3. Any particle-size class, except for fragmental, and more

than 40 percent (by weight) iron oxide as Fe2

O3 (more than

28 percent Fe) extractable by dithionite citrate, in the fineearth fraction.

Ferritic

or

4. Any particle-size class, except for fragmental, and more

than 40 percent (by weight) gibbsite and boehmite in the

fine-earth fraction.

Gibbsitic

or

5. Any particle-size class, except for fragmental, and more

than 40 percent (by weight) magnesium-silicate minerals,

such as the serpentine minerals (antigorite, chrysotile, and

lizardite) plus talc, olivines, Mg-rich pyroxenes, and Mg-rich

amphiboles, in the fine-earth fraction.

Magnesic

or

6. Any particle-size class, except for fragmental, and more

than 20 percent (by weight) glauconitic pellets in the fineearth fraction.

Glauconitic

or

D. Other mineral soil layers or horizons, in the mineralogy

control section, of soils in all other mineral orders and in Terric

subgroups of Histosols and Histels, in a clayey, clayey-skeletal,

fine or very-fine particle-size class, that:

1. In the fine-earth fraction, have a total percent (by

weight) iron oxide as Fe2

O3 (percent Fe by dithionate citrate

times 1.43) plus the percent ( by weight) gibbsite of more

than 10.

Parasesquic

or

2. In the fraction less than 0.002 mm in size:

a. Have more than 50 percent (by weight) halloysite

plus kaolinite and allophane and more halloysite than any

other single mineral.

Halloysitic

or

b. Have more than 50 percent (by weight) kaolinite plus

halloysite, dickite, and nacrite, and other 1:1 or

nonexpanding 2:1 layer minerals and gibbsite and less

than 10 percent (by weight) smectite.

Kaolinitic

or

c. Have more smectite (montmorillonite, beidellite, and

nontronite), by weight, than any other single kind of clay

mineral.

Smectitic

or

d. Have more than 50 percent (by weight) illite

(hydrous mica) and commonly more than 4 percent K2

O.

Illitic

or

e. Have more vermiculite than any other single kind of

clay mineral.

Vermiculitic

or
Family and Series Differentiae and Names 303

F

A

M

f. In more than 50 percent of the thickness, meet all of

the following:

(1) Have no free carbonates; and

(2) The pH of a suspension of 1 g soil in 50 ml 1 M

NaF is more than 8.4 after 2 minutes; and

(3) The ratio of 1500 kPa water to measured clay is

0.6 or more.

Isotic

or

g. All other soils in this category.

Mixed

or

E. All other mineral soil layers or horizons, in the mineralogy

control section, that have:

1. More than 40 percent (by weight) (70 percent by grain

count) mica and stable mica pseudomorphs in the 0.02 to

0.25 mm fraction.

Micaceous

or

2. More than 25 percent (by weight) (45 percent by grain

count) mica and stable mica pseudomorphs in the 0.02 to

0.25 mm fraction.

Paramicaceous

or

3. A total percent (by weight) iron oxide as Fe2

O3 (percent

Fe by dithionate citrate times 1.43) plus the percent (by

weight) gibbsite of more than 10 in the fine-earth fraction.

Parasesquic

or

4. In more than one-half of the thickness, all of the

following:

a. No free carbonates; and

b. NaF pH of 8.4 or more; and

c. A ratio of 1500 kPa water to measured clay of 0.6 or

more.

Isotic

or

5. More than 90 percent (by weight or grain count) silica

minerals (quartz, chalcedony, or opal) and other resistant

minerals in the 0.02 to 2.0 mm fraction.

Siliceous

or

6. All other properties.

Mixed

Cation-Exchange Activity Classes

The cation-exchange activity classes help in making

interpretations of mineral assemblages and of the nutrientholding capacity of soils in mixed and siliceous mineralogy

classes of clayey, clayey-skeletal, coarse-loamy, coarse-silty,

fine, fine-loamy, fine-silty, loamy, loamy-skeletal, and veryfine particle-size classes. Cation-exchange activity classes are

not assigned to Histosols and Histels, and they are not assigned

to Oxisols and “kandi” and “kanhap” great groups and

subgroups of Alfisols and Ultisols because assigning such

classes to them would be redundant. Cation-exchange activity

classes are not assigned to the sandy, sandy-skeletal, or

fragmental particle-size class because the low clay content

causes cation-exchange activity classes to be less useful and

less reliable.

The cation-exchange capacity (CEC) is determined by

NH4OAc at pH 7 on the fine-earth fraction. The CEC of the

organic matter, sand, silt, and clay is included in the

determination. The criteria for the classes use ratios of CEC to

the percent, by weight, of silicate clay, both by weighted

average in the control section. In the following classes “clay”

excludes clay-size carbonates. If the ratio of percent water

retained at 1500 kPa tension to the percentage of measured clay

is 0.25 or less or 0.6 or more in half or more of the particle-size

control section (or part in contrasting families), then the

percentage of clay is estimated by the following formula: Clay

% = 2.5(% water retained at 1500 kPa tension - % organic

carbon).

Control Section for Cation-Exchange Activity Classes

The control section for cation-exchange activity classes is

the same as that used to determine the particle-size and

mineralogy classes. For soils with strongly contrasting particlesize classes, where both named parts of the control section use a

cation-exchange activity class, the class associated with the

particle-size class that has the most clay is named. For example,

in a pedon with a classification of loamy over clayey, mixed,

active, calcareous, thermic Typic Udorthent, the cationexchange activity class “active” is associated with the clayey

part of the control section.

Key to Cation-Exchange Activity Classes

A. Soils that are not Histosols, Histels, or Oxisols, that are not

in “kandi” or “kanhap” great groups or subgroups of Alfisols

and Ultisols, that are in either a mixed or siliceous mineralogy

class, that are not in a fragmental, sandy, or sandy-skeletal

particle-size class or any substitute for a particle-size class, and

that have a ratio of cation-exchange capacity (by NH4OAc at pH

7) to clay (percent by weight) of:

1. 0.60 or more.

Superactive
304 Keys to Soil Taxonomy

2. 0.40 to 0.60.

Active

3. 0.24 to 0.40.

Semiactive

4. Less than 0.24.

Subactive

or

B. All other soils: No cation-exchange activity classes used.

Calcareous and Reaction Classes of Mineral Soils

The presence or absence of carbonates, soil reaction, and the

presence of high concentrations of aluminum in mineral soils

are treated together because they are so intimately related.

There are four classes—calcareous, acid, nonacid, and allic.

These are defined later, in the key to calcareous and reaction

classes. The classes are not used in all taxa, nor is more than

one used in the same taxa.

Use of the Calcareous and Reaction Classes

The calcareous, acid, and nonacid classes are used in the

names of the families of Entisols, Aquands, and Aquepts, except

they are not used in any of the following:

1. Duraquands and Placaquands

2. Sulfaquepts, Fragiaquepts, and Petraquepts

3. Sandy, sandy-skeletal, cindery, pumiceous, or fragmental

families

4. Families with carbonatic or gypsic mineralogy

The calcareous class, in addition to those listed above, is

used in the names of the families of Aquolls, except it is not

used with any of the following:

1. Calciaquolls, Natraquolls, and Argiaquolls

2. Cryaquolls and Duraquolls that have an argillic horizon

3. Families with carbonatic or gypsic mineralogy

The allic class is used only in families of Oxisols.

Control Section for Calcareous and Reaction Classes

The control section for the calcareous class is one of the

following:

1. Soils with a root-limiting layer that is 25 cm or less below

the mineral soil surface: A 2.5-cm-thick layer directly above the

root-limiting layer.

 2. Soils with a root-limiting layer that is 26 to 50 cm below

the mineral soil surface: The layer between a depth of 25 cm

below the mineral soil surface and the root-limiting layer.

3. All other listed soils: Between a depth of 25 and 50 cm

below the mineral soil surface.

The control section for the acid, nonacid, and allic classes is

the same as that for particle-size classes.

Key to Calcareous and Reaction Classes

A. Oxisols that have a layer, 30 cm or more thick within the

control section, that contains more than 2 cmol(+) of KClextractable Al per kg soil in the fine-earth fraction.

Allic

B. Other listed soils that, in the fine-earth fraction, effervesce

(in cold dilute HCl) in all parts of the control section.

Calcareous

C. Other listed soils with a pH of less than 5.0 in 0.01 M CaCl2

(1:2) (about pH 5.5 in H2O, 1:1) throughout the control section.

Acid

D. Other listed soils with a pH of 5.0 or more in 0.01 M CaCl2

(1:2) in some or all layers in the control section.

Nonacid

It should be noted that a soil containing dolomite is

calcareous and that effervescence of dolomite, when treated

with cold dilute HCl, is slow.

The calcareous, acid, nonacid, and allic classes are listed in

the family name, when appropriate, following the mineralogy

and cation-exchange activity classes.

Soil Temperature Classes

Soil temperature classes, as named and defined here, are

used as part of the family name in both mineral and organic

soils. Temperature class names are used as part of the family

name unless the criteria for a higher taxon carry the same

limitation. Thus, frigid is implied in all cryic suborders, great

groups, and subgroups and would be redundant if used in the

names of families within these classes.

The Celsius (centigrade) scale is the standard. It is assumed

that the temperature is that of a soil that is not being irrigated.

Control Section for Soil Temperature

The control section for soil temperature either is at a depth of

50 cm from the soil surface or is at the upper boundary of a

root-limiting layer, whichever is shallower. The soil temperature

classes, defined in terms of the mean annual soil temperature

and the difference between mean summer and mean winter

temperatures, are determined by the following key.

Key to Soil Temperature Classes

A. Gelisols and Gelic suborders and great groups that have a

mean annual soil temperature as follows:

1. -10 oC or lower.

Hypergelic

or
Family and Series Differentiae and Names 305

F

A

M

2. -4 oC to -10 oC.

Pergelic

or

3. +1 o

C to -4 oC.

Subgelic

or

B. Other soils that have a difference in soil temperature of

6 o

C or more between mean summer (June, July, and August in

the Northern Hemisphere) and mean winter (December,

January, and February in the Northern Hemisphere) and a mean

annual soil temperature of:

1. Lower than 8 oC (47 oF).

Frigid

or

2. 8 o

C (47 oF) to 15 oC (59 oF).

Mesic

or

3. 15 o

C (59 oF) to 22 oC (72 oF).

Thermic

or

4. 22 o

C (72 oF) or higher.

Hyperthermic

or

C. All other soils that have a mean annual soil temperature as

follows:

1. Lower than 8 o

C (47 oF).

Isofrigid

or

2. 8 o

C (47 oF) to 15 oC (59 oF).

Isomesic

or

3. 15 o

C (59 oF) to 22 oC (72 oF).

Isothermic

or

4. 22 o

C (72 oF) or higher.

Isohyperthermic

Soil Depth Classes

Soil depth classes are used in all families that have a rootlimiting layer at a specified depth from the mineral soil surface,

except for those families in Lithic subgroups and those with a

fragipan. The root-limiting layers included in soil depth classes

are duripans; petrocalcic, petrogypsic, and placic horizons;

continuous ortstein (90 percent or more); and densic, lithic,

paralithic, and petroferric contacts. Soil depth classes for

Histosols and Histels are given later in this chapter. One soil

depth class name, “shallow,” is used to characterize certain

mineral soil families that have one of the depths indicated in the

following key.

Key to Soil Depth Classes

A. Oxisols that are less than 100 cm deep (from the mineral

soil surface) to a root-limiting layer and are not in a Lithic

subgroup.

Shallow

or

B. Soils in all other mineral soil orders that are less than 50

cm deep (from the mineral soil surface) to a root-limiting layer

and are not in a Lithic subgroup.

Shallow

or

C. All other mineral soils: No soil depth class used.

Rupture-Resistance Classes

In this taxonomy, some partially cemented soil materials,

such as durinodes, serve as differentiae in categories above the

family, while others, such as partially cemented spodic

materials (ortstein), do not. No single family, however, should

include soils both with and without partially cemented horizons.

In Spodosols, a partially cemented spodic horizon is used as a

family differentia. The following rupture-resistance class is

defined for families of Spodosols:

A. Spodosols that have an ortstein horizon.

Ortstein

or

B. All other soils: No rupture-resistance class used.

Classes of Coatings (on Sands)

Despite the emphasis given to particle-size classes in this

taxonomy, variability remains in the sandy particle-size class,

which includes sands and loamy sands. Some sands are very

clean, i.e., almost completely free of silt and clay, while others

are mixed with appreciable amounts of finer grains. Clay is

more efficient at coating sand than is silt. A weighted average

silt (by weight) plus 2 times the weighted average clay (by

weight) of more than 5 makes a reasonable division of the sands

at the family level. Two classes of Quartzipsamments are
306 Keys to Soil Taxonomy

defined in terms of their content of silt plus 2 times their

content of clay.

Control Section for Classes of Coatings

The control section for classes of coatings is the same as that

for particle-size classes or their substitutes and for mineralogy

classes.

Key to Classes of Coatings

A. Quartzipsamments that have a sum of the weighted

average silt (by weight) plus 2 times the weighted average clay

of more than 5.

Coated

or

B. Other Quartzipsamments.

Uncoated

Classes of Permanent Cracks

Some Hydraquents consolidate or shrink after drainage and

become Fluvaquents or Humaquepts. In the process they can

form polyhedrons roughly 12 to 50 cm in diameter, depending

on their n value and texture. These polyhedrons are separated

by cracks that range in width from 2 mm to more than 1 cm.

The polyhedrons may shrink and swell with changes in the

moisture content of the soils, but the cracks are permanent and

can persist for several hundreds of years, even if the soils are

cultivated. The cracks permit rapid movement of water through

the soils, either vertically or laterally. Such soils may have the

same texture, mineralogy, and other family properties as soils

that do not form cracks or that have cracks that open and close

with the seasons. Soils with permanent cracks are very rare in

the United States.

Control Section for Classes of Permanent Cracks

The control section for classes of permanent cracks is from

the base of any plow layer or 25 cm from the soil surface,

whichever is deeper, to 100 cm below the soil surface.

Key to Classes of Permanent Cracks

A. Fluvaquents or Humaquepts that have, throughout a layer

50 cm or more thick, continuous, permanent, lateral and vertical

cracks 2 mm or more wide, spaced at average lateral intervals of

less than 50 cm.

Cracked

or

B. All other Fluvaquents and Humaquepts: No class of

permanent cracks used.

Family Differentiae for Histosols and

Histels

Most of the differentiae that are used to distinguish families

of Histosols and Histels have already been defined, either

because they are used as differentiae in mineral soils as well as

Histosols and Histels or because their definitions are used for

the classification of some Histosols and Histels in categories

higher than the family. In the following descriptions,

differentiae not previously mentioned are defined and the

classes in which they are used are enumerated.

The order in which family classes, if appropriate for a

particular family, are placed in the technical family names of

Histosols and Histels is as follows:

Particle-size classes

Mineralogy classes, including the nature of limnic deposits

in Histosols

Reaction classes

Soil temperature classes

Soil depth classes (used only in Histosols)

Particle-Size Classes

Particle-size classes are used only for the family names of

Terric subgroups of Histosols and Histels. The classes are

determined from the properties of the mineral soil materials in

the control section through use of the key to particle-size

classes. The classes are more generalized than those for soils in

other orders.

Control Section for Particle-Size Classes

The particle-size control section is the upper 30 cm of the

mineral layer or of that part of the mineral layer that is within

the control section for Histosols and Histels (given in chapter

3), whichever is thicker.

Key to Particle-Size Classes of Histosols and Histels

A. Terric subgroups of Histosols and Histels that have (by

weighted average) in the particle-size control section:

1. A fine-earth component of less than 10 percent (including

associated medium and finer pores) of the total volume.

Fragmental

or

2. A texture (of the fine earth) of sand or loamy sand,

including less than 50 percent (by weight) very fine sand in

the fine-earth fraction.

Sandy or sandy-skeletal

or
Family and Series Differentiae and Names 307

F

A

M

3. Less than 35 percent clay in the fine-earth fraction and a

content of rock fragments of 35 percent or more of the total

volume.

Loamy-skeletal

or

4. A content of rock fragments of 35 percent or more of

the total volume.

Clayey-skeletal

or

5. A clay content of 35 percent or more in the fine-earth

fraction.

Clayey

or

6. All other Terric subgroups of Histosols and Histels.

Loamy

or

B. All other Histosols and Histels: No particle-size class

used.

Mineralogy Classes

There are three different kinds of mineralogy classes

recognized for families in certain great groups and subgroups of

Histosols. The first kind is the ferrihumic soil material defined

below. The second is three types of limnic materials—

coprogenous earth, diatomaceous earth, and marl, defined in

chapter 3. The third is mineral layers of Terric subgroups. The

key to mineralogy classes for these mineral layers is the same as

that for mineral soils. Terric subgroups of Histels also have the

same mineralogy classes as those for mineral soils.

Ferrihumic Mineralogy Class

Ferrihumic soil material, i.e., bog iron, is an authigenic

(formed in place) deposit consisting of hydrated iron oxide

mixed with organic matter, either dispersed and soft or

cemented into large aggregates, in a mineral or organic layer

that has all of the following characteristics:

1. Saturation with water for more than 6 months per year (or

artificial drainage);

2. 2 percent or more (by weight) iron concretions having

lateral dimensions ranging from less than 5 to more than 100

mm and containing 10 percent or more (by weight) free iron

oxide (7 percent or more Fe) and 1 percent or more (by weight)

organic matter; and

3. A dark reddish or brownish color that changes little on

drying.

The ferrihumic mineralogy class is used for families of

Fibrists, Hemists, and Saprists, but it is not used for

Sphagnofibrists and Sphagnic subgroups of other great groups.

If the ferrihumic class is used in the family name of a Histosol,

no other mineralogy classes are used in that family because the

presence of iron is considered to be by far the most important

mineralogical characteristic.

Mineralogy Classes Applied Only to Limnic Subgroups

Limnic materials (defined in chapter 3) with a thickness of 5

cm or more are mineralogy class criteria if the soil does not also

have ferrihumic mineralogy. The following family classes are

used: coprogenous, diatomaceous, and marly.

Control Section for the Ferrihumic Mineralogy Class and

Mineralogy Classes Applied to Limnic Subgroups

The control section for the ferrihumic mineralogy class and

the classes applied to Limnic subgroups is the same as the

control section for Histosols.

Mineralogy Classes Applied Only to Terric Subgroups

For Histosols and Histels in Terric subgroups, use the same

key to mineralogy classes as that used for mineral soils unless a

Histosol also has ferrihumic mineralogy.

Control Section for Mineralogy Classes Applied Only to

Terric Subgroups

For Terric subgroups of Histosols and Histels, use the same

control section for mineralogy classes as that used for the

particle-size classes.

Key to Mineralogy Classes

A. Histosols (except for Folists), Sphagnofibrists, and

Sphagnic subgroups of other great groups that have ferrihumic

soil material within the control section for Histosols.

Ferrihumic

or

B. Other Histosols that have, within the control section for

Histosols, limnic materials, 5 cm or more thick, that consist of:

1. Coprogenous earth.

Coprogenous

or

2. Diatomaceous earth.

Diatomaceous

or

3. Marl.

Marly

or
308 Keys to Soil Taxonomy

C. Histels and other Histosols in Terric subgroups: Use the

key to mineralogy classes for mineral soils.

or

D. All other Histels and Histosols: No mineralogy class used.

Reaction Classes

Reaction classes are used in all families of Histosols and

Histels. The two classes recognized are defined in the following

key:

A. Histosols and Histels that have a pH value, on undried

samples, of 4.5 or more (in 0.01 M CaCl2) in one or more

layers of organic soil materials within the control section for

Histosols.

Euic

or

B. All other Histosols and Histels.

Dysic

Soil Temperature Classes

The soil temperature classes of Histosols are determined

through use of the same key and definitions as those used for

mineral soils. Histels have the same temperature classes as other

Gelisols.

Soil Depth Classes

Soil depth classes refer to the depth to a root-limiting layer, a

fragmental particle-size class, or a cindery or pumiceous

substitute class. The root-limiting layers included in soil depth

classes of Histosols are duripans; petrocalcic, petrogypsic, and

placic horizons; continuous ortstein; and densic, lithic,

paralithic, and petroferric contacts. The following key is used

for families in all subgroups of Histosols. The shallow class is

not used in the suborder Folists.

Key to Soil Depth Classes

A. Histosols that are less than 18 cm deep to a root-limiting

layer, to a fragmental particle-size class, or to a cindery or

pumiceous substitute class.

Micro

or

B. Other Histosols, excluding Folists, that have a root-limiting

layer, a fragmental particle-size class, or a cindery or

pumiceous substitute class at a depth between 18 and 50 cm

from the soil surface.

Shallow

or

C. All other Histosols: No soil depth class used.

Series Differentiae Within a Family

The function of the series is pragmatic, and differences

within a family that affect the use of a soil should be considered

in classifying soil series. The separation of soils at the series

level of this taxonomy can be based on any property that is used

as criteria at higher levels in the system. The criteria most

commonly used include presence of, depth to, thickness of, and

expression of horizons and properties diagnostic for the higher

categories and differences in texture, mineralogy, soil moisture,

soil temperature, and amounts of organic matter. The limits of

the properties used as differentiae must be more narrowly

defined than the limits for the family. The properties used,

however, must be reliably observable or be inferable from other

soil properties or from the setting or vegetation.

The differentiae used must be within the series control

section. Differences in soil or regolith that are outside the series

control section and that have not been recognized as series

differentiae but are relevant to potential uses of certain soils are

considered as a basis for phase distinctions.

Control Section for the Differentiation of Series

The control section for the soil series is similar to that for the

family, but it differs in a few important respects. The particlesize and mineralogy control sections for families end at the

upper boundary of a fragipan, duripan, or petrocalcic horizon

because these horizons have few roots. In contrast to the control

section for the series, the thickness of such horizons is not taken

into account in the control sections for the family. The series

control section includes materials starting at the soil surface and

also the first 25 cm below a densic or paralithic contact if its

upper boundary is less than 125 cm below the mineral soil

surface. Properties of horizons and layers below the particlesize control section, a depth between 100 and 150 cm (or to 200

cm if in a diagnostic horizon) from the mineral soil surface, also

are considered.

Key to the Control Section for the Differentiation of Series

The part of a soil to be considered in differentiating series

within a family is as follows:

A. Mineral soils that have permafrost within 150 cm of the

soil surface: From the soil surface to the shallowest of the

following:

1. A lithic or petroferric contact; or

2. A depth of 100 cm if the depth to permafrost is less than

75 cm; or

3. 25 cm below the upper boundary of permafrost if

that boundary is 75 cm or more below the soil surface; or
Family and Series Differentiae and Names 309

F

A

M

4. 25 cm below a densic or paralithic contact; or

5. A depth of 150 cm; or

B. Other mineral soils: From the soil surface to the shallowest

of the following:

1. A lithic or petroferric contact; or

2. A depth of either 25 cm below a densic or paralithic

contact or 150 cm below the soil surface, whichever is

shallower, if there is a densic or paralithic contact within 150

cm; or

3. A depth of 150 cm if the bottom of the deepest

diagnostic horizon is less than 150 cm from the soil surface;

or

4. The lower boundary of the deepest diagnostic horizon or

a depth of 200 cm, whichever is shallower, if the lower

boundary of the deepest diagnostic horizon is 150 cm or

more below the soil surface; or

C. Organic soils (Histosols and Histels): From the soil surface

to the shallowest of the following:

1. A lithic or petroferric contact; or

2. A depth of 25 cm below a densic or paralithic contact;

or

3. A depth of 100 cm if the depth to permafrost is less than

75 cm; or

4. 25 cm below the upper boundary of permafrost if that

boundary is between a depth of 75 and 125 cm below the

soil surface; or

5. The base of the bottom tier.

311

H

O

R

This chapter describes soil layers and genetic soil horizons.

The genetic horizons are not the equivalent of the diagnostic

horizons of Soil Taxonomy. While designations of genetic

horizons express a qualitative judgment about the kinds of

changes that are believed to have taken place in a soil,

diagnostic horizons are quantitatively defined features that are

used to differentiate between taxa. A diagnostic horizon may

encompass several genetic horizons, and the changes implied

by genetic horizon designations may not be large enough to

justify recognition of different diagnostic horizons.

Master Horizons and Layers

The capital letters O, L, A, E, B, C, R, M, and W represent

the master horizons and layers of soils. These letters are the

base symbols to which other characters are added to complete

the designations. Most horizons and layers are given a single

capital-letter symbol; some require two.

O horizons or layers: Layers dominated by organic

material. Some are saturated with water for long periods or

were once saturated but are now artificially drained; others

have never been saturated.

Some O layers consist of undecomposed or partially

decomposed litter (such as leaves, needles, twigs, moss, and

lichens) that has been deposited on the surface. They may be on

top of either mineral or organic soils. Other O layers consist of

organic material that was deposited under saturated conditions

and has decomposed to varying stages. The mineral fraction of

such material constitutes only a small percentage of the volume

of the material and generally much less than half of its weight.

Some soils consist entirely of materials designated as O

horizons or layers.

An O layer may be on the surface of a mineral soil, or it may

be at any depth below the surface if it is buried. A horizon

formed by the illuviation of organic material into a mineral

subsoil is not an O horizon, although some horizons that have

formed in this manner contain considerable amounts of organic

matter.

L horizons or layers: Limnic horizons or layers include

both organic and mineral limnic materials that were either (1)

deposited in water by precipitation or through the actions of

aquatic organisms, such as algae and diatoms, or (2) derived

from underwater and floating aquatic plants and subsequently

modified by aquatic animals.

L horizons or layers include coprogenous earth,

(sedimentary peat), diatomaceous earth, and marl. They occur

only in Histosols. They have only the following subordinate

distinctions: co, di, or ma. They do not have the subordinate

distinctions of the other master horizons and layers.

A horizons: Mineral horizons that have formed at the

surface or below an O horizon. They exhibit obliteration of all

or much of the original rock structure1

 and show one or both of

the following: (1) an accumulation of humified organic matter

closely mixed with the mineral fraction and not dominated by

properties characteristic of E or B horizons (defined below) or

(2) properties resulting from cultivation, pasturing, or similar

kinds of disturbance.

If a surface horizon has properties of both A and E horizons

but the feature emphasized is an accumulation of humified

organic matter, it is designated as an A horizon. In some areas,

such as areas of warm, arid climates, the undisturbed surface

horizon is less dark than the adjacent underlying horizon and

contains only small amounts of organic matter. It has a

morphology distinct from the C layer, although the mineral

fraction is unaltered or only slightly altered by weathering.

Such a horizon is designated as an A horizon because it is at the

surface. Recent alluvial or eolian deposits that retain fine

stratification are not considered to be A horizons unless

cultivated.

E horizons: Mineral horizons in which the main feature is

the loss of silicate clay, iron, aluminum, or some combination of

these, leaving a concentration of sand and silt particles. These

horizons exhibit obliteration of all or much of the original rock

structure.

An E horizon is most commonly differentiated from an

underlying B horizon in the same sequum by a color of higher

value or lower chroma, or both, by coarser texture, or by a

combination of these properties. In some soils the color of the E

horizon is that of the sand and silt particles, but in many soils

coatings of iron oxides or other compounds mask the color of

the primary particles. An E horizon is most commonly

differentiated from an overlying A horizon by its lighter color. It

generally contains less organic matter than the A horizon. An E

horizon is commonly near the surface, below an O or A horizon

CHAPTER 18

Designations for Horizons and Layers

1Rock structure includes fine stratification in unconsolidated soil materials as well as

pseudomorphs of weathered minerals that retain their positions relative to each other and to

unweathered minerals in saprolite.
312 Keys to Soil Taxonomy

and above a B horizon, but eluvial horizons that are within or

between parts of the B horizon or extend to depths greater than

those of normal observation can be assigned the letter E if they

are pedogenic.

B horizons: Horizons that have formed below an A, E, or O

horizon. They are dominated by the obliteration of all or much

of the original rock structure and show one or more of the

following:

1. Illuvial concentration of silicate clay, iron, aluminum,

humus, carbonates, gypsum, or silica, alone or in

combination;

2. Evidence of the removal or addition of carbonates;

3. Residual concentration of oxides;

4. Coatings of sesquioxides that make the horizon

conspicuously lower in color value, higher in chroma, or

redder in hue, without apparent illuviation of iron;

5. Alteration that forms silicate clay or liberates oxides, or

both, and that forms a granular, blocky, or prismatic structure

if volume changes accompany changes in moisture content;

6. Brittleness; or

7. Strong gleying.

All of the different kinds of B horizons are, or were

originally, subsurface horizons. Included as B horizons, where

contiguous to other genetic horizons, are layers of illuvial

concentration of carbonates, gypsum, or silica that are the result

of pedogenic processes (and may or may not be cemented) and

brittle layers that show other evidence of alteration, such as

prismatic structure or illuvial accumulation of clay.

Examples of layers that are not B horizons are layers in

which clay films either coat rock fragments or cover finely

stratified unconsolidated sediments, regardless of whether the

films were formed in place or by illuviation; layers into which

carbonates have been illuviated but that are not contiguous to an

overlying genetic horizon; and layers with gleying but no other

pedogenic changes.

C horizons or layers: Horizons or layers, excluding

strongly cemented and harder bedrock, that are little affected by

pedogenic processes and lack the properties of O, A, E, or B

horizons. Most are mineral layers. The material of C layers may

be either like or unlike the material from which the solum has

presumably formed. The C horizon may have been modified,

even if there is no evidence of pedogenesis.

Included as C layers are sediment, saprolite, bedrock, and

other geologic materials that are moderately cemented or less

cemented. The excavation difficulty in these materials

commonly is low or moderate. Some soils form in material that

is already highly weathered, and if such material does not meet

the requirements for A, E, or B horizons, it is designated by the

letter C. Changes that are not considered pedogenic are those

not related to the overlying horizons. Some layers that have

accumulations of silica, carbonates, gypsum, or more soluble

salts are included in C horizons, even if cemented. If a

cemented layer formed through pedogenic processes, however,

it is considered a B horizon.

R layers: Strongly cemented to indurated bedrock.

Granite, basalt, quartzite, limestone, and sandstone are

examples of bedrock designated by the letter R. The excavation

difficulty commonly exceeds high. The R layer is sufficiently

coherent when moist to make hand-digging with a spade

impractical, although the layer may be chipped or scraped.

Some R layers can be ripped with heavy power equipment. The

bedrock may have cracks, but these are generally too few and

too small to allow root penetration. The cracks may be coated

or filled with clay or other material.

M layers: Root-limiting subsoil layers consisting of nearly

continuous, horizontally oriented, human-manufactured

materials

Examples of materials designated by the letter M are

geotextile liners, asphalt, concrete, rubber, and plastic.

W layers: Water

This symbol indicates water layers within or beneath the

soil. The water layer is designated as Wf if it is permanently

frozen and as W if it is not permanently frozen. The W (or Wf)

designation is not used for shallow water, ice, or snow above

the soil surface.

Transitional and Combination Horizons

Horizons dominated by properties of one master horizon but

having subordinate properties of another.—Two capital-letter

symbols are used for such transitional horizons, e.g., AB, EB,

BE, or BC. The first of these symbols indicates that the

properties of the horizon so designated dominate the

transitional horizon. An AB horizon, for example, has

characteristics of both an overlying A horizon and an

underlying B horizon, but it is more like the A horizon than the

B horizon.

In some cases a horizon can be designated as transitional

even if one of the master horizons to which it presumably forms

a transition is not present. A BE horizon may be recognized in a

truncated soil if its properties are similar to those of a BE

horizon in a soil from which the overlying E horizon has not

been removed by erosion. A BC horizon may be recognized

even if no underlying C horizon is present; it is transitional to

assumed parent materials.

Horizons with two distinct parts that have recognizable

properties of the two kinds of master horizons indicated by the

capital letters.—The two capital letters designating such

combination horizons are separated by a virgule (/), e.g., E/B,

B/E, or B/C. Most of the individual parts of one horizon

component are surrounded by the other. The designation may

be used even when horizons similar to one or both of the

components are not present, provided that the separate
Designations for Horizons and Layers 313

H

O

R

components can be recognized in the combination horizon. The

first symbol is that of the horizon with the greater volume.

Single sets of horizon designators do not cover all situations;

therefore, some improvising is needed. For example, Argic

Udipsamments have lamellae that are separated from each other

by eluvial layers. Because it is generally not practical to

describe each lamella and eluvial layer as a separate horizon,

the horizons can be combined but the components described

separately. One horizon then has several lamellae and eluvial

layers and can be designated an “E and Bt” horizon. The

complete horizon sequence for these soils could be: Ap-Bw-E

and Bt1-E and Bt2-C.

Suffix Symbols

Lowercase letters are used as suffixes to designate specific

kinds of master horizons and layers. The term “accumulation”

is used in many of the definitions of such horizons to indicate

that these horizons must contain more of the material in

question than is presumed to have been present in the parent

material. The suffix symbols and their meanings are as follows:

a Highly decomposed organic material

This symbol is used with O to indicate the most highly

decomposed organic materials, which have a fiber content

of less than 17 percent (by volume) after rubbing.

b Buried genetic horizon

This symbol is used in mineral soils to indicate

identifiable buried horizons with major genetic features

that were developed before burial. Genetic horizons may

or may not have formed in the overlying material, which

may be either like or unlike the assumed parent material

of the buried soil. This symbol is not used in organic

soils, nor is it used to separate an organic layer from a

mineral layer.

c Concretions or nodules

This symbol indicates a significant accumulation of

concretions or nodules. Cementation is required. The

cementing agent commonly is iron, aluminum,

manganese, or titanium. It cannot be silica, dolomite,

calcite, or more soluble salts.

co Coprogenous earth

This symbol, used only with L, indicates a limnic layer

of coprogenous earth (or sedimentary peat).

d Physical root restriction

This symbol indicates noncemented, root-restricting

layers in naturally occurring or human-made sediments or

materials. Examples are dense basal till, plowpans, and

other mechanically compacted zones.

di Diatomaceous earth

This symbol, used only with L, indicates a limnic layer

of diatomaceous earth.

e Organic material of intermediate decomposition

This symbol is used with O to indicate organic

materials of intermediate decomposition. The fiber

content of these materials is 17 to 40 percent (by volume)

after rubbing.

f Frozen soil or water

This symbol indicates that a horizon or layer contains

permanent ice. The symbol is not used for seasonally

frozen layers or for dry permafrost.

ff Dry permafrost

This symbol indicates a horizon or layer that is

continually colder than 0 oC and does not contain enough

ice to be cemented by ice. This suffix is not used for

horizons or layers that have a temperature warmer than

0 oC at some time of the year.

g Strong gleying

This symbol indicates either that iron has been reduced

and removed during soil formation or that saturation with

stagnant water has preserved it in a reduced state. Most of

the affected layers have chroma of 2 or less, and many

have redox concentrations. The low chroma can represent

either the color of reduced iron or the color of uncoated

sand and silt particles from which iron has been removed.

The symbol g is not used for materials of low chroma that

have no history of wetness, such as some shales or E

horizons. If g is used with B, pedogenic change in

addition to gleying is implied. If no other pedogenic

change besides gleying has taken place, the horizon is

designated Cg.

h Illuvial accumulation of organic matter

This symbol is used with B to indicate the

accumulation of illuvial, amorphous, dispersible

complexes of organic matter and sesquioxides if the

sesquioxide component is dominated by aluminum but is

present only in very small quantities. The organosesquioxide material coats sand and silt particles. In some

horizons these coatings have coalesced, filled pores, and

cemented the horizon. The symbol h is also used in

combination with s as “Bhs” if the amount of the

sesquioxide component is significant but the color value

and chroma, moist, of the horizon are 3 or less.

i Slightly decomposed organic material

This symbol is used with O to indicate the least

decomposed of the organic materials. The fiber content of
314 Keys to Soil Taxonomy

these materials is 40 percent or more (by volume) after

rubbing.

j Accumulation of jarosite

Jarosite is a potassium or iron sulfate mineral that is

commonly an alteration product of pyrite that has been

exposed to an oxidizing environment. Jarosite has hue of

2.5Y or yellower and normally has chroma of 6 or more,

although chromas as low as 3 or 4 have been reported.

jj Evidence of cryoturbation

Evidence of cryoturbation includes irregular and

broken horizon boundaries, sorted rock fragments, and

organic soil materials occurring as bodies and broken

layers within and/or between mineral soil layers. The

organic bodies and layers are most commonly at the

contact between the active layer and the permafrost.

k Accumulation of secondary carbonates

This symbol indicates an accumulation of visible

pedogenic calcium carbonate (less than 50 percent, by

volume). Carbonate accumulations occur as carbonate

filaments, coatings, masses, nodules, disseminated

carbonate, or other forms.

kk Engulfment of horizon by secondary carbonates

This symbol indicates major accumulations of

pedogenic calcium carbonate. The suffix kk is used when

the soil fabric is plugged with fine grained pedogenic

carbonate (50 percent or more, by volume) that occurs as

an essentially continuous medium. The suffix

corresponds to the stage III plugged horizon or higher of

the carbonate morphogenetic stages (Gile et al., 1966).

m Cementation or induration

This symbol indicates continuous or nearly continuous

cementation. It is used only for horizons that are more

than 90 percent cemented, although they may be

fractured. The cemented layer is physically rootrestrictive. The dominant cementing agent (or the two

dominant ones) may be indicated by adding defined letter

suffixes, singly or in pairs. The horizon suffix km

indicates cementation by carbonates; qm, cementation by

silica; sm, cementation by iron; ym, cementation by

gypsum; kqm, cementation by lime and silica; and zm,

cementation by salts more soluble than gypsum.

ma Marl

This symbol, used only with L, indicates a limnic layer

of marl.

n Accumulation of sodium

This symbol indicates an accumulation of

exchangeable sodium.

o Residual accumulation of sesquioxides

This symbol indicates a residual accumulation of

sesquioxides.

p Tillage or other disturbance

This symbol indicates a disturbance of the surface

layer by mechanical means, pasturing, or similar uses. A

disturbed organic horizon is designated Op. A disturbed

mineral horizon is designated Ap even though it is clearly

a former E, B, or C horizon.

q Accumulation of silica

This symbol indicates an accumulation of secondary

silica.

r Weathered or soft bedrock

This symbol is used with C to indicate cemented layers

(moderately cemented or less cemented). Examples are

weathered igneous rock and partly consolidated sandstone,

siltstone, or shale. The excavation difficulty is low to high.

s Illuvial accumulation of sesquioxides and organic matter

This symbol is used with B to indicate an

accumulation of illuvial, amorphous, dispersible

complexes of organic matter and sesquioxides if both the

organic-matter and sesquioxide components are

significant and if either the color value or chroma, moist,

of the horizon is 4 or more. The symbol is also used in

combination with h as “Bhs” if both the organic-matter

and sesquioxide components are significant and if the

color value and chroma, moist, are 3 or less.

ss Presence of slickensides

This symbol indicates the presence of slickensides.

Slickensides result directly from the swelling of clay

minerals and shear failure, commonly at angles of 20 to

60 degrees above horizontal. They are indicators that

other vertic characteristics, such as wedge-shaped peds

and surface cracks, may be present.

t Accumulation of silicate clay

This symbol indicates an accumulation of silicate

clay that either has formed within a horizon and

subsequently has been translocated within the horizon or

has been moved into the horizon by illuviation, or both.

At least some part of the horizon should show evidence of

clay accumulation either as coatings on surfaces of peds

or in pores, as lamellae, or as bridges between mineral

grains.

u Presence of human-manufactured materials (artifacts)

This symbol indicates the presence of manufactured

artifacts that have been created or modified by humans,

usually for a practical purpose in habitation,
Designations for Horizons and Layers 315

H

O

R

manufacturing, excavation, or construction activities.

Examples of artifacts are processed wood products, liquid

petroleum products, coal, combustion by-products,

asphalt, fibers and fabrics, bricks, cinder blocks, concrete,

plastic, glass, rubber, paper, cardboard, iron and steel,

altered metals and minerals, sanitary and medical waste,

garbage, and landfill waste.

v Plinthite

This symbol indicates the presence of iron-rich,

humus-poor, reddish material that is firm or very firm

when moist and hardens irreversibly when exposed to the

atmosphere and to repeated wetting and drying.

w Development of color or structure

This symbol is used with B to indicate the

development of color or structure, or both, with little or

no apparent illuvial accumulation of material. It should

not be used to indicate a transitional horizon.

x Fragipan character

This symbol indicates a genetically developed layer

that has a combination of firmness and brittleness and

commonly a higher bulk density than the adjacent layers.

Some part of the layer is physically root-restrictive.

y Accumulation of gypsum

This symbol indicates an accumulation of gypsum.

z Accumulation of salts more soluble than gypsum

This symbol indicates an accumulation of salts that are

more soluble than gypsum.

Conventions for Using Letter Suffixes

Many master horizons and layers that are symbolized by a

single capital letter have one or more lowercase letter suffixes.

The following rules apply:

1. Letter suffixes should directly follow the capital letter.

2. More than three suffixes are rarely used.

3. If more than one suffix is needed, the following letters,

if used, are written first: a, d, e, h, i, r, s, t, and w. Except in

the Bhs or Crt2 horizon designations, none of these letters are

used in combination in a single horizon.

4. If more than one suffix is needed and the horizon is not

buried, the following symbols, if used, are written last: c, f,

g, m, v, and x. Some examples: Btc, Bkm, and Bsv.

5. If a horizon is buried, the suffix b is written last. It is

used only for buried mineral soils.

A B horizon that has a significant accumulation of clay and

also shows evidence of a development of color or structure, or

both, is designated Bt (t has precedence over w, s, and h). A B

horizon that is gleyed or has accumulations of carbonates,

sodium, silica, gypsum, or salts more soluble than gypsum or

residual accumulations of sesquioxides carries the appropriate

symbol: g, k, n, q, y, z, or o. If illuvial clay also is present, t

precedes the other symbol: Bto.

Unless needed for explanatory purposes, the suffixes h, s,

and w are not used with g, k, n, q, y, z, or o.

Vertical Subdivision

Commonly, a horizon or layer identified by a single letter or

a combination of letters has to be subdivided. For this purpose,

Arabic numerals are added to the letters of the horizon

designation. These numerals follow all the letters. Within a C

horizon, for example, successive layers may be designated C1,

C2, C3, etc. If the lower part is gleyed and the upper part is

not gleyed, the layers may be designated C1-C2-Cg1-Cg2 or

C-Cg1-Cg2-R.

These conventions apply whatever the purpose of the

subdivision. In many soils a horizon that could be identified

by a single set of letters is subdivided because of the need to

recognize differences in morphological features, such as

structure, color, or texture. These divisions are numbered

consecutively with Arabic numerals, but the numbering starts

again with 1 wherever in the profile any letter of the horizon

symbol changes, e.g., Bt1-Bt2-Btk1-Btk2 (not Bt1-Bt2-Btk3-

Btk4). The numbering of vertical subdivisions within a

horizon is not interrupted at a discontinuity (indicated by a

numerical prefix) if the same letter combination is used in

both materials, e.g., Bs1-Bs2-2Bs3-2Bs4 (not Bs1-Bs2-2Bs1-

2Bs2).

During sampling for laboratory analyses, thick soil horizons

are sometimes subdivided even though differences in

morphology are not evident in the field. These subdivisions are

identified by Arabic numerals that follow the respective horizon

designations. For example, four layers of a Bt horizon sampled

by 10-cm increments are designated Bt1, Bt2, Bt3, and Bt4. If

the horizon has already been subdivided because of differences

in morphological features, the set of Arabic numerals that

identifies the additional sampling subdivisions follows the first

numeral. For example, three layers of a Bt2 horizon sampled by

10-cm increments are designated Bt21, Bt22, and Bt23. The

descriptions for each of these sampling subdivisions can be the

same, and a statement indicating that the horizon has been

subdivided only for sampling purposes can be added.

Discontinuities

Arabic numerals are used as prefixes to horizon designations

(preceding the letters A, E, B, C, and R) to indicate 2 Indicates weathered bedrock or saprolite in which clay films are present. discontinuities in mineral soils. These prefixes are distinct from
316

the Arabic numerals that are used as suffixes denoting vertical

subdivisions.

A discontinuity that can be identified by a number prefix is a

significant change in particle-size distribution or mineralogy

that indicates a difference in the material from which the

horizons have formed and/or a significant difference in age,

unless that difference in age is indicated by the suffix b.

Symbols that identify discontinuities are used only when they

can contribute substantially to an understanding of the

relationships among horizons. The stratification common to

soils that formed in alluvium is not designated as a

discontinuity, unless particle-size distribution differs markedly

from layer to layer (i.e., particle-size classes are strongly

contrasting), even though genetic horizons may have formed in

the contrasting layers.

Where a soil has formed entirely in one kind of material, the

whole profile is understood to be material 1 and the number

prefix is omitted from the symbol. Similarly, the uppermost

material in a profile consisting of two or more contrasting

materials is understood to be material 1, but the number is

omitted. Numbering starts with the second layer of contrasting

material, which is designated 2. Underlying contrasting layers

are numbered consecutively. Even when the material of a layer

below material 2 is similar to material 1, it is designated 3 in the

sequence; the numbers indicate a change in materials, not types

of material. Where two or more consecutive horizons have

formed in the same kind of material, the same prefix number is

applied to all the designations of horizons in that material: ApE-Bt1-2Bt2-2Bt3-2BC. The suffix numbers designating

subdivisions of the Bt horizon continue in consecutive order

across the discontinuity.

If an R layer is present below a soil that has formed in

residuum and if the material of the R layer is judged to be like

the material from which the soil has developed, the Arabicnumber prefix is not used. The prefix is used, however, if it is

thought that the R layer would produce material unlike that in

the solum, e.g., A-Bt-C-2R or A-Bt-2R. If part of the solum has

formed in residuum, the symbol R is given the appropriate

prefix: Ap-Bt1-2Bt2-2Bt3-2C1-2C2-2R.

A buried horizon (designated by the letter b) presents special

problems. It is obviously not in the same deposit as the

overlying horizons. Some buried horizons, however, have

formed in material that is lithologically like the overlying

deposit. A prefix is not used to distinguish material of such a

buried horizon. If the material in which a horizon of a buried

soil has formed is lithologically unlike the overlying material,

however, the discontinuity is indicated by a number prefix and

the symbol for the buried horizon also is used, e.g., Ap-Bt1-

Bt2-BC-C-2ABb-2Btb1-2Btb2-2C.

Discontinuities between different kinds of layers in organic

soils are not identified. In most cases such differences are

identified either by letter-suffix designations if the different

layers are organic or by the master symbol if the different layers

are mineral.

Use of the Prime Symbol

If two or more horizons of the same kind are separated by

one or more horizons of a different kind in a pedon, identical

letter and number symbols can be used for those horizons that

have the same characteristics. For example, the sequence A-EBt-E-Btx-C identifies a soil that has two E horizons. To

emphasize this characteristic, the prime symbol ( ́) is added

after the master-horizon symbol of the lower of the two

horizons that have identical designations, e.g., A-E-Bt-E ́-BtxC. The prime symbol, when appropriate, is applied to the

capital-letter horizon designation, and any lowercase letter

symbols follow it: B ́t. The prime symbol is used only when the

letter designations of the two layers in question are completely

identical. In the rare cases when three layers have identical

letter symbols, double prime symbols can be used for the lowest

of these layers: E ́ ́.

The same principle applies in designating layers of organic

soils. The prime symbol is used only to distinguish two or more

horizons that have identical symbols, e.g., Oi-C-O ́i-C ́ (when

the soil has two identical Oi layers) or Oi-C-Oe-C ́ (when the

two C layers are of the same kind).

Use of the Caret Symbol

The "caret" symbol (^) is used as a prefix to master horizon

designations to indicate mineral or organic layers of humantransported material. This material has been moved horizontally

onto a pedon from a source area outside of that pedon by

directed human activity, usually with the aid of machinery. All

horizons and layers formed in human-transported material are

indicated by a "caret" prefix (e.g., ^A-^C-Ab-Btb). When they

can contribute substantially to an understanding of the

relationship of the horizons or layers, Arabic numeral prefixes

may be used before the caret symbol to indicate the presence of

discontinuities within the human-transported material or

between the human- transported material and underlying layers

(e.g., ^A-^C1-2^C2-3Bwb).

Literature Cited

Gile, L.H., F.F. Peterson, and R.B. Grossman. 1966.

Morphological and Genetic Sequences of Carbonate

Accumulation in Desert Soils. Soil Sci. 101: 347–360.
317

Appendix

Laboratory Methods for Soil Taxonomy

The standard laboratory methods upon which the operational

definitions of this edition of Soil Taxonomy are based are

described in the Soil Survey Laboratory Methods Manual (Burt,

2004). Copies of standard laboratory data sheets are included

with the typifying pedons in the chapters on soil orders in this

edition of Soil Taxonomy. For specific information about an

analytical procedure, these data sheets should be checked and

reference should be made to the Soil Survey Laboratory

Methods Manual. Much of the information included in this

appendix is derived from “Soil Survey Laboratory Methods for

Characterizing Physical and Chemical Properties and

Mineralology of Soils” (Kimble, Knox, and Holzhey, 1993).

Also, the information is summarized the Soil Survey Laboratory

Information Manual (USDA, NRCS, 1995).

Pedon characterization data, or any soil survey data, are most

useful when the operations for collecting the data are well

understood. The mental pictures and conceptual definitions that

aid in visualizing properties and processes often differ from the

information supplied by an analysis. Also, results differ by

method, even though two methods may carry the same name or

the same concept. There is uncertainty in comparing one bit of

data with another without knowledge of how both bits were

gathered. Operational definitions, definitions tied to a specific

method, are needed. This soil taxonomy has many class limits

(at all levels) that are based on chemical or physical properties

determined in the laboratory. One can question a given limit,

but that is not the purpose of this appendix. This appendix is

written to show what procedures are used for given class limits.

By using specific class limits, everyone will come to the same

classification if they follow the same procedures.

This taxonomy is based almost entirely on criteria that are

defined operationally. One example is the definition of particlesize classes. There is no one definition of clay that works well

for all soils. Hence, an operation for testing the validity of a

clay measurement and a default operation for those situations

where the clay measurement is not valid are defined. The

default method is based on a water content at 1500 kPa and on

content of organic carbon.

Data Elements Used in Classifying Soils

Detailed explanations of laboratory methods are given in the

Soil Survey Laboratory Methods Manual (Burt, 2004). Each

method is listed by code on the data sheet at the beginning of

the chapters describing soil orders. On the data sheets presented

with each order, the method code is shown for each

determination made. These data sheets should be consulted for

reference to the Soil Survey Laboratory Methods Manual. This

manual specifies method codes for pedon sampling, sample

handling, site selection, sample collection, and sample

preparation.

The units of measure reported on the data sheets are not SI

units. Following are SI conversions:

1 meq/100 g = 1 cmol(+)/kg

1 mmho/cm = 1 dS/m

15 bar = 1500 kPa

1

/3 bar = 33 kPa

1

/10 bar = 10 kPa

In this taxonomy the terms (1) particle-size analysis (size

separates), (2) texture, and (3) particle-size classes are all used.

Particle-size analysis is needed to determine texture and

particle-size classes. Texture differs from particle-size class in

that texture includes only the fine-earth fraction (less than 2

mm), while particle size includes both the fraction less than 2

mm in size and the fraction equal to or more than 2 mm.

Physical Analyses

Atterberg limits are determined on the fraction less than

0.4 mm in size. Plasticity index is the difference in water

content between liquid limit and plastic limit. It is the range

of water content over which a soil paste can be deformed

without breaking, but it does not include flow as a liquid

under operationally defined conditions. Liquid limit is the

minimum water content at which the paste begins to flow as a

liquid. Samples that do not deform without breaking at any

water content are reported as NP, nonplastic. Operational

definitions are in the Annual Book of ASTM Standards (ASTM,

1998).

Bulk density is obtained typically by equilibration of Sarancoated natural fabric clods at designated pressure differentials.

Bulk densities are determined at two or more water contents.

For coarse textured and moderately coarse textured soils, they

are determined when the sample is at 10 kPa suction and when

ovendry. For soils of medium and finer texture, the bulk

densities are determined when the sample is at 33 kPa suction

and when ovendry.
318 Keys to Soil Taxonomy

Bulk density determined at 33 kPa suction is used to convert

other analytical results to a volumetric basis (for example, kg of

organic carbon per m3).

Coefficient of linear extensibility (COLE) is a derived value.

It is computed from the difference in bulk density between a

moist clod and an ovendry clod. It is based on the shrinkage of

a natural soil clod between a water content of 33 kPa (10 kPa

for sandier soils) and ovendry.

Linear extensibility (LE) of a soil layer is the product of the

thickness, in centimeters, multiplied by the COLE of the layer

in question. The LE of a soil is the sum of these products for all

soil horizons. COLE multiplied by 100 is called linear

extensibility percent (LEP).

Water retention difference (WRD) is computed from water

retentions at 33 kPa (10 kPa for sandier soils) and 1500 kPa

suction. It is converted to cm of water per cm of soil through

use of the bulk density. The 33 or 10 kPa water is determined

by desorption of the natural fabric clods, and the 1500 kPa

water is determined by desorption of crushed soil.

Chemical Analyses

Aluminum saturation is the amount of KCl-extractable Al

divided by extractable bases (extracted by ammonium acetate)

plus the KCl-extractable Al. It is expressed as percent. A

general rule of thumb is that if there is more than 50 percent Al

saturation, Al problems in the soil are likely. The problems may

not be related to Al toxicity but to a deficiency of calcium and/

or magnesium.

Ammonium-oxalate-extractable aluminum, iron, and silicon

are determined by a single extraction made in the dark with 0.2

molar ammonium oxalate at a pH of 3.5. The amount of

aluminum, iron, and silicon is measured by atomic absorption

and reported as a percentage of the total dry weight of the fineearth fraction. These values are used as criteria in identifying

soils in the Andisol and Spodosol orders and in the andic and

spodic subgroups in other orders. They also are used to

determine amorhic and ferrihydric mineralogy classes. The

procedure extracts iron, aluminum, and silicon from organic

matter and from amorphous mineral material. It is used in

conjunction with dithionite-citrate and pyrophosphate

extractions to identify the sources of iron and aluminum in the

soil. Pyrophosphate extracts iron and aluminum from organic

matter. Dithionite citrate extracts iron from iron oxides and

oxyhydroxides as well as from organic matter.

Base saturation is reported on the data sheets as percent of

the CEC. It is reported as CEC by sum of cations at pH 8.2 and

by ammonium acetate at pH 7. Base saturation by ammonium

acetate is equal to the sum of the bases extracted by ammonium

acetate, divided by the CEC (by ammonium acetate), and

multiplied by 100. If extractable calcium is not reported on the

data sheet because of free carbonates or salts in the sample, then

the base saturation is assumed to be 100 percent.

Base saturation percentage by sum of cations is equal to the

sum of bases extracted by ammonium acetate, divided by the

CEC (by sum of cations), and multiplied by 100. This value is

not reported if either extractable calcium or extractable acidity

is omitted.

Differences between the two methods of determining base

saturation reflect the amount of the pH-dependent CEC. Class

definitions in this taxonomy specify which method is used.

The sum of exchangeable cations is considered equal to the

sum of bases extracted by ammonium acetate unless carbonates,

gypsum, or other salts are present. When these salts are present,

the sum of the bases extracted by ammonium acetate typically

exceeds 100 percent of the CEC. Therefore, a base saturation of

100 percent is assumed. The amount of calcium from

carbonates is usually much larger than the amount of

magnesium from the carbonates. Extractable calcium is not

shown on the data sheet if more than a trace (more than 0.4

percent) of carbonates (reported as calcium carbonate) is

present or if calculated base saturation exceeds 110 percent,

based on CEC by ammonium acetate at pH 7.

Calcium carbonate equivalent is the amount of carbonates in

the soil as measured by treating the sample with HCl. The

evolved carbon dioxide is measured manometrically. The

amount of carbonate is then calculated as a calcium carbonate

equivalent regardless of the form of carbonates (dolomite,

sodium carbonate, magnesium carbonate, etc.) in the sample.

Calcium carbonate equivalent is reported as a percentage of the

total dry weight of the sample. It can be reported on material

that is less than 2 mm or less than 20 mm in size.

Calcium sulfate as gypsum is determined by extraction in

water and precipitation in acetone. The amount of gypsum is

reported as a percentage of the total dry weight of the fraction

less than 2 mm in size and the fraction less than 20 mm in size.

Drying soils to oven-dryness, the standard base for reporting

the data, removes part of the water of hydration from the

gypsum. Many measured values, particularly water retention

values, must be recalculated to compensate for the weight of the

water of hydration lost during drying.

Cation-exchange capacity (CEC) by ammonium acetate (at

pH 7), by sum of cations (at pH 8.2), and by bases plus

aluminum is given on the data sheets in the chapters on soil

orders. The CEC depends on the method of analysis as well as

the nature of the exchange complex. CEC by sum of cations at

pH 8.2 is calculated by adding the sum of bases and the

extractable acidity. CEC by ammonium acetate is measured at

pH 7. CEC by bases plus aluminum, or effective cationexchange capacity (ECEC), is derived by adding the sum of

bases and KCl-extractable Al. Aluminum extracted by 1N KCl

is negligible if the extractant pH rises toward 5.5. ECEC then is

equal to extractable bases. CEC and ECEC are reported on the

data sheets as meq/100 g soil.

The reported CEC may differ from the CEC of the soil at its

natural pH. The standard methods allow the comparison of one
Appendix 319

soil with another even though the pH of the extractant differs

from the pH of the natural soil. Cation-exchange capacity by

ammonium acetate and by sum of cations applies to all soils.

CEC at pH 8.2 is not reported if the soil contains free

carbonates because bases are extracted from the carbonates. The

effective CEC (ECEC) is reported only for acid soils. ECEC is

not reported for soils having soluble salts, although it can be

calculated by subtracting the soluble components from the

extractable components. ECEC also may be defined as bases

plus aluminum plus hydrogen. That is the more common

definition for agronomic interpretations. This taxonomy

specifies bases plus aluminum.

Generally, the ECEC is less than the CEC at pH 7, which in

turn is less than the CEC at pH 8.2. If the soil is dominated by

positively charged colloids (e.g., iron oxides), however, the

trend is reversed. Most soils have negatively charged colloids,

which cause the CEC to increase with increasing pH. This

difference in CEC is commonly called the pH-dependent or

variable charge. The CEC at the soil pH can be estimated by

plotting the CEC of the soil vs. the pH of the extractant on a

graph and reading the CEC at the soil pH.

CEC measurements at pH levels other than those described

in the paragraphs above and CEC derived by use of other

cations will yield somewhat different results. It is important to

know the procedure, pH, and cation used before evaluating

CEC data or comparing data from different sources.

Citric-acid-extractable phosphorus (acid-soluble phosphate)

is used to separate the mollic epipedon (less than 1,500 mg/kg

P2

O5) from the anthropic epipedon (equal to or more than 1,500

mg/kg).

Color of sodium-pyrophosphate extract is used as a criterion

in the separation of different types of organic materials. A

saturated solution is made by adding 1 g of sodium

pyrophosphate to 4 ml of distilled water, and a moist organic

matter sample is added to the solution. The sample is mixed and

allowed to stand overnight, chromatographic paper is dipped in

the solution, and the color of the paper is ascertained through

use of a Munsell color chart.

Electrical conductivity (EC) is the conductivity of the water

extracted from saturated paste. The EC is used to determine the

total content of salts. It is reported as mmhos/cm, which is

equal to dS/m.

Exchangeable magnesium and calcium plus exchangeable

acidity (at pH 8.2) is used as a criterion for the natric horizon.

The exchangeable acidity is measured at pH 8.2, and the

magnesium and calcium are extracted at pH 7.0 with

ammonium acetate. See the paragraphs about extractable acidity

and exchangeable bases.

Exchangeable sodium percentage (ESP) is reported as a

percentage of the CEC by ammonium acetate at pH 7. Watersoluble sodium is converted to meq/100 g soil. This value is

subtracted from extractable sodium, divided by the CEC (by

ammonium acetate), and multiplied by 100. An ESP of more

than 15 percent is used in this taxonomy as a criterion for the

natric horizon.

Extractable acidity is the acidity released from the soil by a

barium chloride-triethanolamine solution buffered at pH 8.2. It

includes all the acidity generated by replacement of the

hydrogen and aluminum from permanent and pH-dependent

exchange sites. It is reported as meq/100 g soil. Extractable

acidity data are reported on some data sheets as exchangeable

acidity and on others as exchangeable H+.

Extractable aluminum is exchangeable aluminum extracted

by 1N KCl. It is a major constituent only in strongly acid soils

(pH of less than 5.0). Aluminum will precipitate if the pH rises

above 4.5 to 5.0 during analysis. The extractant KCl usually

affects the soil pH 1 unit or less. Extractable aluminum is

measured at the NSSL by atomic absorption. Many laboratories

measure the aluminum by titration with a base to the

phenopthalein end point. Titration measures exchangeable

acidity as well as extractable aluminum. Soils with a pH below

4.0 or 4.5 are likely to have values determined by atomic

absorption similar to values determined by titration because

very little hydrogen is typically on the exchange complex. If

there is a large percentage of organic matter, however, some

hydrogen may be present. For some soils it is important to

know which procedure was used. Extractable aluminum is

reported as meq/100 g soil.

Extractable bases (calcium, magnesium, sodium, and

potassium) are extracted with ammonium acetate buffered at pH

7. They are equilibrated, filtered in an auto-extractor, and

measured by atomic absorption. They are reported as meq/100 g

soil. The bases are extracted from the cation-exchange complex

by displacement with ammonium ions. The term “extractable

bases” is used instead of “exchangeable bases” because soluble

salts and some bases from carbonates can be included in the

extract.

Sum of bases is the sum of the calcium, magnesium, sodium,

and potassium described in the previous paragraph.

Iron and aluminum extracted by citrate are removed in a

single extraction. They are measured by atomic absorption and

reported as a percentage of the total dry weight. The iron is

primarily from ferric oxides (hematite, magnetite) and iron

oxyhydroxides (goethite). Aluminum substituted into these

minerals is extracted simultaneously. The dithionite reduces the

ferric iron, and the citrate stabilizes the iron by chelation. Iron

and aluminum bound in organic matter are extracted if the

citrate is a stronger chelator than the organic molecules.

Manganese extracted by this procedure also is recorded. The

iron extracted is commonly related to the clay distribution

within a pedon.

Melanic index is used in the identification of the melanic

epipedon. The index is related to the ratio of the humic and

fulvic acids in the organic fraction of the soil (Honna,

Yamamoto, and Matsui, 1988). About 0.50 gram of air-dried

soil material that is less than 2 mm in size is shaken with 25 ml
320 Keys to Soil Taxonomy

of 0.5 percent NaOH solution in a 50-ml centrifuge tube for 1

hour at room temperature. One drop of a flocculating agent is

added, and the mixture is centrifuged at 4,000 rpm for 10

minutes. The melanic index is the ratio of the absorbance at 450

nm over that at 520 nm.

Nitrogen in the NSSL data base is reported as a percentage

of the total dry weight. A soil sample is combusted at high

temperature with oxygen to release NOx, and the N2 is

measured by thermal conductivity detection.

Optical density of the ammonium oxalate extract (ODOE) is

determined with a spectrophotometer using a 430 nm

wavelength. An increase in the ODOE value in an illuvial

horizon, relative to an overlying eluvial horizon, indicates an

accumulation of translocated organic materials.

Organic carbon data in the National Soil Survey Laboratory

(NSSL) data base have been determined mostly by wet

digestion (Walkley, 1935). Because of environmental concerns

about waste products, however, that procedure is no longer in

use. The only procedure that is currently used to determine

organic carbon is a dry combustion procedure that determines

the percent of total carbon. The content of organic carbon is

determined by subtracting the amount of carbon contributed by

carbonates from total carbon data. The content of organic

carbon determined by this computation is very close to the

content determined by the wet digestion procedure.

pH is measured in water and in salts. The pH measured in

water is determined in distilled water typically mixed 1:1 with

dry soil. The pH measured in potassium chloride is determined

in 1N KCl solution mixed 1:1 with soil. The pH measured in

calcium chloride is determined in 0.01M CaCl2

 solution mixed

2:1 with soil.

The pH is measured by a pH meter in a soil-water or soil-salt

solution. The extent of the dilution is shown in the heading on

the data sheets. A ratio of 1:1 means one part dry soil and one

part water, by weight.

Measurement of pH in a dilute salt solution is common

because it tends to mask seasonal variations in pH. Readings in

0.01M CaCl2 tend to be uniform regardless of the time of year.

Readings in 1N KCl also tend to be uniform. The former are

more popular in regions with less acid soils. The latter are more

popular in regions with more acid soils. If KCl is used to extract

exchangeable aluminum, the pH reading (in KCl) shows the pH

at which the aluminum was extracted.

pH in sodium fluoride (NaF pH) is measured in a suspension

of 1 gram of soil in 50 ml 1M NaF after stirring for 2 minutes.

A NaF pH of 9.4 or more is a strong indicator that short-rangeorder minerals dominate the soil exchange complex. A NaF pH

of 8.4 or more is a criterion for the isotic mineralogy class. It

indicates a significant component of short-range-order

minerals in the exchange complex. Soil materials with free

carbonates also have high NaF pH values. NaF is poisonous

with ingestion and eye contact and moderately hazardous with

skin contact.

Phosphate retention (P ret.) refers to the percent phosphorus

retained by soil after equilibration with 1,000 mg/kg

phosphorus solution for 24 hours. This procedure is used in the

classification of andic soil materials. It identifies soils in which

phosphorus fixation may be a problem affecting agronomic

uses.

Potassium-hydroxide-extractable aluminum is determined by

atomic absorption spectrophotometry. This procedure has been

used in the past but is not used in this taxonomy. The data can

be used in the field to estimate the amount of ammoniumoxalate-extractable aluminum.

Sodium adsorption ratio (SAR) was developed as a measure

of irrigation water quality. Water-soluble sodium is divided by

water-soluble calcium and magnesium. The formula is SAR =

Na/[(Ca+Mg)/2]0.5. An SAR of 13 or more is used as an

alternate to the ESP criterion for the natric horizon.

Sodium-pyrophosphate-extractable iron and aluminum are

determined by a single extraction and measured by atomic

absorption. Results are reported as a percentage of the total dry

weight. This procedure has been used widely to extract iron and

aluminum from organic matter. It successfully removes much of

the organo-metal accumulations in spodic horizons but extracts

little of the inorganically bound iron and aluminum.

Total salts is calculated from the electrical conductivity of

the saturation extract. It is reported as a weight percentage of

the total water-soluble salts in the soil.

Water-soluble cations and anions are determined in water

extracted from a saturated paste. The cations include calcium,

magnesium, sodium, and potassium, and the anions include

carbonate, bicarbonate, sulfate, chloride, nitrate, fluoride,

phosphate, silicate, and borate. The cations and anions can be

reported as cmol(+)/l.

Water-soluble sulfate is used in the definition of the sulfuric

horizon. The sulfate is determined in the saturation extract and

is reported as one of the anions.

Mineral Analyses

Mineralogy of the clay, silt, and sand fractions is needed for

classification in some taxa. X-ray diffraction (XRD) and

thermal and petrographic analyses are classically viewed as

mineralogy techniques, although some mineralogy classes (e.g.,

ferritic, amorphic, gypsic, carbonatic, and isotic) are determined

by chemical and/or physical analyses.

Halloyisite, illite, kaolinite, smectite, vermiculite, and other

minerals in the clay fraction (less than 0.002 mm) may be

identified by XRD analysis. Relative peak positions identify

clay minerals, and peak intensities are the basis for semiquantitative estimates of mineral percent by weight in the clay

fraction. The NRCS Soil Survey Laboratory (SSL) reports

relative peak intensities of clay minerals from XRD in a fiveclass system that generally corresponds to percent by weight of

a mineral (class 1 = 0 to 2 percent, class 2 = 3 to 9 percent,
Appendix 321

class 3 = 10 to 29 percent, class 4 = 30 to 49 percent, and class

5 = more than 50 percent). There are multiple potential

interferences in the analysis of a clay sample (Burt, 2004). Peak

intensities may be attenuated by one or more interferences, and

the reported class may underestimate the actual amount of

mineral present. Thus, these assigned percentages are given for

informational use only and should not be used to quantify

minerals in a clay fraction. Clay minerals are listed in the order

of decreasing quantity on the data sheet. XRD is used to

determine smectitic, vermiculitic, illitic, kaolinitic, or

halloysitic mineralogy classes in Soil Taxonomy. Some family

classes require a clay mineral to be more than one-half (by

weight) of the clay fraction, corresponding to XRD class 5.

Other mineralogy classes require more of the specified mineral

than any other single mineral, corresponding to the clay mineral

being listed first on the SSL data sheet.

Kaolinite and gibbsite may be determined by thermal

analysis. Results from this analysis are reported as percent by

weight in the clay fraction and are more quantitative than the

results of XRD for these minerals. Thermal analysis is a

technique in which the dried sample (typically the clay fraction)

is heated in a controlled environment. Certain minerals undergo

decomposition at specific temperature ranges, and the mineral

can be quantified when compared to standard clays. Results

may be used to determine kaolinitic and gibbsitic family

mineralogy classes, complementary to or in lieu of XRD data.

Resistant minerals, weatherable minerals, volcanic glass,

magnesium-silicate minerals, glauconitic pellets, mica, and

stable mica pseudomorphs may be determined by petrographic

analysis. Magnesium-silicate minerals (e.g., serpentine

minerals) and glauconitic pellets are reported as percent by

weight in the fine-earth fraction (less than 2.0 mm). Resistant

minerals, weatherable minerals, and volcanic glass, are

determined as percent of total grains counted in the coarse silt

through very coarse sand (0.02 to 2.0 mm) fractions, while mica

and stable mica pseudomorphs are determined in the 0.02 to

0.25 mm fractions (coarse silt, very fine sand, and fine sand).

Individual mineral grains in a specific particle-size fraction

are mounted on a glass slide, identified, and counted (at least

300 grains) under a polarizing light microscope. Data are

reported as percent of grains counted for a specific size fraction.

This percentage is generally regarded as equivalent to weight

percent for spherical minerals. Alternative techniques are

available for determining weight percent micas and other platy

grains in a soil separate. The usual SSL protocol is to count

mineral grains in either the coarse silt (0.02-0.05 mm), very fine

sand (0.05-0.1 mm), or fine sand (0.10-0.25 mm) fraction,

whichever one has the highest weight percent based on particlesize analysis. Mineral or glass content in the analyzed fraction

is assumed to be representative of the content in the whole 0.02

to 2.0 mm or fine-earth fraction. It may be necessary to count

additional fractions to obtain a reliable estimate of volcanic

glass content in soil materials with a non-uniform distribution

of glass in dominant particle-size fractions. If more than one

fraction is counted, the weighted average of the counted

fractions may be calculated to represent glass content in the

0.02 to 2.0 mm fraction. For soils expected to have significant

amounts of glass in dominant fractions of medium, coarse, or

very coarse sand, a request is made to count grains in the larger

fractions.

Two general types of petrographic analysis are conducted in

the Soil Survey Laboratory: (a) complete mineral grain count,

in which all minerals in the sample are identified and counted,

or (b) a glass count, in which glass, glass aggregates, glasscoated minerals, and glassy materials are identified and

quantified and all other minerals are counted as “other.” “Glasscoated grains” are crystalline mineral grains (e.g., quartz and

feldspar) in which more than 50 percent of the grain is covered

in glass. “Glassy materials” is a general category for grains that

have optical properties of glass but lack definitive

characteristics of glass, glass-coated grains, or glass aggregates.

Percent of total resistant minerals is reported on the SSL data

sheet. (Calcite and more soluble minerals are included in

determinations of the percentage of resistant minerals reported

on the laboratory data sheet but are not included in the values

used in this taxonomy.) Total percent volcanic glass,

weatherable minerals, or other groups of minerals used in

classification may be calculated by summing the percent of

individual minerals included in the group. A complete list of

minerals in each category is in the Soil Survey Laboratory

Methods Manual (Burt, 2004).

Other Information Useful in Classifying Soils

Volumetric amounts of organic carbon are used in some

taxonomic criteria. The following calculation is used: (Datum

[percent] times bulk density [at 33 or 10 kPa] times thickness

[cm]) divided by 10. This calculation is normally used for

organic carbon, but it can be used for some other

measurements. Each horizon is calculated separately, and the

product of the calculations can be summed to any desired depth,

commonly 100 cm.

Ratios that can be developed from the data are useful in

making internal checks of the data, in making managementrelated interpretations, and in answering taxonomic questions.

Some of the ratios are used as criteria in determining argillic,

kandic, or oxic horizons.

The ratio of 1500 kPa water to clay is used to indicate the

relevancy of the particle-size determination. If the ratio is 0.6 or

more and the soil does not have andic soil properties,

incomplete dispersion of the clay is assumed and clay is

estimated by the following formula: Clay % = 2.5(% water

retained at 1500 kPa tension - % organic carbon). For a typical

soil with well dispersed clays, the ratio is 0.4. Some soil-related

factors that can cause deviation from the 0.4 value are: (1) lowactivity clays (kaolinites, chlorites, and some micas), which

tend to have a ratio of 0.35 or below; (2) iron oxides and claysize carbonates, which tend to decrease the ratio; (3) organic
322 Keys to Soil Taxonomy

matter, which increases the ratio because it increases the water

content at 1500 kPa; (4) andic and spodic materials and

materials with an isotic mineralogy class, which increase the

ratio because they do not disperse well; (5) large amounts of

gypsum; and (6) clay minerals within grains of sand and silt.

These clay minerals hold water at 1500 kPa and thus increase

the ratio. They are most common in shale and in pseudomorphs

of primary minerals in saprolite.

The ratio of CEC by ammonium acetate at pH 7 to clay can

be used to estimate clay mineralogy and clay dispersion. If the

ratio is multiplied by 100, the product is cmol(+)/kg clay. The

following ratios are typical for the following classes of clay

mineralogy: less than 0.2, kaolinitic; 0.2-0.3, kaolinitic or

mixed; 0.3-0.5, mixed or illitic; 0.5-0.7, mixed or smectitic; and

more than 0.7, smectitic. These ratios are most valid when some

detailed mineralogy data are available. If the ratio of 1500 kPa

water to clay is 0.25 or less or 0.6 or more, the ratio of CEC by

ammonium acetate to clay is not valid. Ratios of 1500 kPa

water to clay of 0.6 or more are typical of poorly dispersed

clays, andic and spodic materials, and materials with an isotic

mineralogy class, and ratios of less than 0.3 are common in

some soils that contain large amounts of gypsum.

A ratio of CEC at pH 8.2 to 1500 kPa water of more than 1.5

and more exchange acidity than the sum of bases plus KClextractable Al imply a soil with a high pH-dependent charge.

Along with bulk density data, they help to distinguish soils that

have andic and spodic materials or soils that have materials with

an isotic mineralogy class from soils with minerals that are

more crystalline.

Literature Cited

American Society for Testing and Materials. 1998. Annual

Book of ASTM Standards. Vol. 4.08, D 4318-95a.

Burt, R., ed. 2004 Soil Survey Laboratory Methods Manual.

Soil Survey Investigations Report 42, Version 4.0. United States

Department of Agriculture, Natural Resources Conservation

Service, National Soil Survey Center.

Honna,T., S. Yamamoto, and K. Matsui. 1988. A Simple

Procedure to Determine Melanic Index That Is Useful for

Differentiating Melanic from Fulvic Andisols. Pedol. 32:

69-78.

Kimble, J.M, E.G. Knox, and C.S. Holzhey. 1993. Soil

Survey Laboratory Methods for Characterizing Physical and

Chemical Properties and Mineralology of Soils. In Applications

of Agriculture Analysis in Environmental Studies, ASTM Spec.

Pub. 1162, K.B. Hoddinott and T.A. O’Shay, eds.

United States Department of Agriculture, Natural Resources

Conservation Service. 1995. Soil Survey Laboratory

Information Manual. National Soil Survey Center, Soil Survey

Laboratory, Soil Survey Investigations Report 45.

Walkley, A. 1935. An Examination of Methods for

Determining Organic Carbon and Nitrogen in Soils. J. Agr. Sci.

25: 598-609.
Appendix 323

Percentages of clay (less than 0.002 mm), silt (0.002 to 0.05 mm),

and sand (0.05 to 2.0 mm) in the basic soil textural classes

325

Index

A

A horizons. See Horizons and layers.

Abrupt textural change ............................................................ 14

Acraquox ............................................................................... 235

Acroperox .............................................................................. 236

Acrotorrox ............................................................................. 240

Acrudox ................................................................................. 241

Acrustox ................................................................................ 245

Agric horizon ............................................................................. 9

Alaquods ................................................................................ 251

Albaqualfs ............................................................................... 35

Albaquults ............................................................................. 262

Albic horizon ............................................................................. 9

Albic materials......................................................................... 15

Albolls ................................................................................... 192

Alfisols .................................................................................... 35

Alorthods ............................................................................... 257

Andic soil properties ............................................................... 15

Andisols ................................................................................... 77

Anhydrous conditions ............................................................. 15

Anhyorthels ........................................................................... 145

Anhyturbels ........................................................................... 149

Aniso class ............................................................................. 296

Anthracambids....................................................................... 108

Anthrepts ............................................................................... 159

Anthropic epipedon ................................................................... 5

Aqualfs .................................................................................... 35

Aquands................................................................................... 77

Aquents .................................................................................. 123

Aquepts .................................................................................. 159

Aquerts .................................................................................. 283

Aquic conditions...................................................................... 23

Aquic moisture regime. See Soil moisture regimes.

Aquicambids .......................................................................... 108

Aquisalids .............................................................................. 122

Aquiturbels ............................................................................ 149

Aquods................................................................................... 251

Aquolls .................................................................................. 193

Aquorthels ............................................................................. 145

Aquox .................................................................................... 235

Aquults .................................................................................. 261

Arents .................................................................................... 127

Argialbolls ............................................................................. 192

Argiaquolls ............................................................................ 193

Argicryids .............................................................................. 112

Argicryolls ............................................................................. 197

Argids ...................................................................................... 97

Argidurids.............................................................................. 115

Argigypsids............................................................................ 118

Argillic horizon ....................................................................... 10

Argiorthels ............................................................................. 146

Argiudolls .............................................................................. 202

Argiustolls ............................................................................. 209

Argixerolls ............................................................................. 225

Aridic moisture regime. See Soil moisture regimes.

Aridisols .................................................................................. 97

B

B horizons. See Horizons and layers.

Bottom tier ............................................................................... 23

Buried soils ................................................................................ 2

C

C horizons or layers. See Horizons and layers.

Calcareous and reaction classes for mineral soils ................. 304

Calciaquerts ........................................................................... 284

Calciaquolls ........................................................................... 193

Calciargids ............................................................................... 97

Calcic horizon.......................................................................... 10

Calcicryepts ........................................................................... 166

Calcicryids ............................................................................. 113

Calcicryolls ............................................................................ 198

Calcids ................................................................................... 105

Calcigypsids .......................................................................... 119

Calcitorrerts ........................................................................... 287

Calciudolls ............................................................................. 204

Calciustepts............................................................................ 178

Calciusterts ............................................................................ 290

Calciustolls ............................................................................ 213

Calcixerepts ........................................................................... 184

Calcixererts ............................................................................ 293

Calcixerolls ............................................................................ 227

Cambic horizon ....................................................................... 11

Cambids ................................................................................. 108

Caret symbol in horizon designators ..................................... 316

Cation-exchange activity classes for mineral soils ................ 303

Chemical analyses ................................................................ 318
326 Keys to Soil Taxonomy

Coatings (classes) on sands ................................................... 305

Coefficient of linear extensibility (COLE) .............................. 16

Control section of Histosols and Histels ................................. 22

Coprogenous earth. See Organic soil material.

Cryalfs ..................................................................................... 44

Cryands .................................................................................... 81

Cryaqualfs ............................................................................... 37

Cryaquands .............................................................................. 78

Cryaquents ............................................................................. 124

Cryaquepts ............................................................................. 160

Cryaquods.............................................................................. 252

Cryaquolls ............................................................................. 194

Cryepts ................................................................................... 166

Cryerts ................................................................................... 287

Cryic temperature regime. See Soil temperature

regimes.

Cryids .................................................................................... 112

Cryods ................................................................................... 253

Cryofibrists ............................................................................ 153

Cryofluvents .......................................................................... 128

Cryofolists ............................................................................. 154

Cryohemists ........................................................................... 155

Cryolls ................................................................................... 197

Cryopsamments ..................................................................... 139

Cryorthents ............................................................................ 134

Cryosaprists ........................................................................... 156

Cryoturbation........................................................................... 24

Cryrendolls ............................................................................ 201

D

Densic contact ......................................................................... 25

Densic materials ...................................................................... 25

Diagnostic subsurface horizons ................................................. 9

Diagnostic surface horizons ...................................................... 5

Diatomaceous earth. See Organic soil material.

Discontinuities identified by horizon designators ................. 315

Duraqualfs ............................................................................... 37

Duraquands.............................................................................. 78

Duraquerts ............................................................................. 284

Duraquods ............................................................................. 252

Duraquolls ............................................................................. 194

Duricryands ............................................................................. 81

Duricryods ............................................................................. 253

Duricryolls ............................................................................. 198

Durids .................................................................................... 115

Durihumods ........................................................................... 256

Durinodes ................................................................................ 16

Duripan .................................................................................... 11

Duritorrands............................................................................. 85

Durixeralfs ............................................................................... 71

Durixerepts ............................................................................ 185

Durixererts ............................................................................. 293

Durixerolls ............................................................................. 227

Durorthods............................................................................. 257

Durudands ............................................................................... 86

Durudepts .............................................................................. 172

Durustalfs ................................................................................ 60

Durustands............................................................................... 92

Durustepts .............................................................................. 179

Durustolls .............................................................................. 214

Dystraquerts ........................................................................... 284

Dystrocryepts......................................................................... 166

Dystrogelepts......................................................................... 171

Dystroxerepts......................................................................... 186

Dystrudepts ............................................................................ 173

Dystruderts ............................................................................ 289

Dystrustepts ........................................................................... 179

Dystrusterts ............................................................................ 290

E

E horizons. See Horizons and layers.

Endoaqualfs ............................................................................. 37

Endoaquands ........................................................................... 78

Endoaquents .......................................................................... 124

Endoaquepts .......................................................................... 161

Endoaquerts ........................................................................... 285

Endoaquods ........................................................................... 252

Endoaquolls ........................................................................... 194

Endoaquults ........................................................................... 262

Entisols .................................................................................. 123

Epiaqualfs ................................................................................ 39

Epiaquands .............................................................................. 79

Epiaquents ............................................................................. 125

Epiaquepts ............................................................................. 162

Epiaquerts .............................................................................. 286

Epiaquods .............................................................................. 253

Epiaquolls .............................................................................. 195

Epiaquults .............................................................................. 262

Epipedon .................................................................................... 5

Eutraquox .............................................................................. 235

Eutrogelepts ........................................................................... 171

Eutroperox ............................................................................. 237

Eutrotorrox ............................................................................ 240

Eutrudepts .............................................................................. 175

Eutrudox ................................................................................ 242

Eutrustox ............................................................................... 246

F

Family differentiae for Histosols and Histels ........................ 306

Family differentiae for mineral soils ..................................... 295

Ferrudalfs................................................................................. 49

Fibers. See Organic soil material.

Fibric soil materials. See Organic soil material.

Fibristels ................................................................................ 143

Fibrists ................................................................................... 153
Index 327

Fluvaquents............................................................................ 125

Fluvents ................................................................................. 128

Folistels .................................................................................. 144

Folistic epipedon ....................................................................... 6

Folists .................................................................................... 154

Fragiaqualfs ............................................................................. 41

Fragiaquepts .......................................................................... 163

Fragiaquods ........................................................................... 253

Fragiaquults ........................................................................... 263

Fragic soil properties ............................................................... 16

Fragihumods.......................................................................... 256

Fragiorthods........................................................................... 257

Fragipan ................................................................................... 11

Fragiudalfs ............................................................................... 49

Fragiudepts ............................................................................ 177

Fragiudults ............................................................................. 268

Fragixeralfs .............................................................................. 72

Fragixerepts ........................................................................... 187

Fraglossudalfs.......................................................................... 49

Frigid temperature regime. See Soil temperature regimes.

Fulvicryands ............................................................................ 82

Fulvudands .............................................................................. 86

G

Gelands .................................................................................... 84

Gelaquands .............................................................................. 79

Gelaquents ............................................................................. 126

Gelaquepts ............................................................................. 163

Gelepts ................................................................................... 171

Gelic materials......................................................................... 25

Gelifluvents ........................................................................... 129

Gelisols .................................................................................. 143

Gelods .................................................................................... 255

Gelolls.................................................................................... 200

Gelorthents ............................................................................ 134

Glacic layer .............................................................................. 25

Glacistels ............................................................................... 144

Glossaqualfs ............................................................................ 41

Glossic horizon ........................................................................ 11

Glossocryalfs ........................................................................... 44

Glossudalfs .............................................................................. 50

Gypsiargids.............................................................................. 99

Gypsic horizon ........................................................................ 12

Gypsicryids............................................................................ 113

Gypsids .................................................................................. 118

Gypsitorrerts .......................................................................... 288

Gypsiusterts ........................................................................... 291

H

Halaquepts ............................................................................. 164

Haplanthrepts......................................................................... 159

Haplaquox ............................................................................. 236

Haplargids.............................................................................. 100

Haplocalcids .......................................................................... 105

Haplocambids ........................................................................ 109

Haplocryalfs ............................................................................ 45

Haplocryands........................................................................... 82

Haplocryepts .......................................................................... 168

Haplocryerts .......................................................................... 287

Haplocryids ........................................................................... 114

Haplocryods........................................................................... 254

Haplocryolls .......................................................................... 199

Haplodurids ........................................................................... 116

Haplofibrists .......................................................................... 154

Haplogelods........................................................................... 255

Haplogelolls........................................................................... 200

Haplogypsids ......................................................................... 120

Haplohemists ......................................................................... 155

Haplohumods......................................................................... 256

Haplohumults ........................................................................ 265

Haploperox ............................................................................ 238

Haplorthels ............................................................................ 146

Haplorthods ........................................................................... 258

Haplosalids ............................................................................ 122

Haplosaprists ......................................................................... 156

Haplotorrands .......................................................................... 85

Haplotorrerts .......................................................................... 288

Haplotorrox ........................................................................... 241

Haploturbels .......................................................................... 149

Haploxeralfs ............................................................................ 72

Haploxerands........................................................................... 95

Haploxerepts.......................................................................... 188

Haploxererts .......................................................................... 294

Haploxerolls .......................................................................... 229

Haploxerults .......................................................................... 280

Hapludalfs ............................................................................... 51

Hapludands .............................................................................. 87

Hapluderts ............................................................................. 289

Hapludolls ............................................................................. 205

Hapludox ............................................................................... 243

Hapludults ............................................................................. 269

Haplustalfs ............................................................................... 60

Haplustands ............................................................................. 92

Haplustepts ............................................................................ 180

Haplusterts ............................................................................. 291

Haplustolls ............................................................................. 215

Haplustox............................................................................... 247

Haplustults ............................................................................. 276

Haprendolls ........................................................................... 201

Hemic soil materials. See Organic soil material.

Hemistels ............................................................................... 144

Hemists .................................................................................. 155

Histels .................................................................................... 143

Histic epipedon .......................................................................... 6

Historthels.............................................................................. 146

Histosols ................................................................................ 153
328 Keys to Soil Taxonomy

Histoturbels ........................................................................... 149

Horizons and layers ............................................................... 311

A horizons ......................................................................... 311

B horizons.......................................................................... 312

C horizons or layers ........................................................... 312

E horizons .......................................................................... 311

L horizons or layers ........................................................... 311

M layers ............................................................................. 312

O horizons or layers .......................................................... 311

R layers .............................................................................. 312

W layers ............................................................................. 312

Humaquepts........................................................................... 164

Humicryepts .......................................................................... 169

Humicryerts ........................................................................... 287

Humicryods ........................................................................... 254

Humigelods ........................................................................... 255

Humilluvic material. See Organic soil material.

Humods ................................................................................. 256

Humults ................................................................................. 265

Hydraquents........................................................................... 126

Hydrocryands .......................................................................... 83

Hydrudands ............................................................................. 89

Hyperthermic temperature regime. See Soil temperature

regimes.

I

Identifiable secondary carbonates ........................................... 17

Inceptisols .............................................................................. 159

Interfingering of albic materials .............................................. 17

Isofrigid temperature regime. See Soil temperature

regimes.

Isohyperthermic temperature regime. See Soil temperature

regimes.

Isomesic temperature regime. See Soil temperature

regimes.

Isothermic temperature regime. See Soil temperature

regimes.

K

Kandiaqualfs............................................................................ 42

Kandiaquults .......................................................................... 263

Kandic horizon ........................................................................ 12

Kandihumults ........................................................................ 266

Kandiperox ............................................................................ 239

Kandiudalfs ............................................................................. 55

Kandiudox ............................................................................. 244

Kandiudults ........................................................................... 270

Kandiustalfs ............................................................................. 63

Kandiustox............................................................................. 248

Kandiustults ........................................................................... 277

Kanhaplaquults ...................................................................... 263

Kanhaplohumults................................................................... 267

Kanhapludalfs .......................................................................... 56

Kanhapludults........................................................................ 272

Kanhaplustalfs ......................................................................... 64

Kanhaplustults ....................................................................... 278

Key to soil orders..................................................................... 31

L

L horizons or layers. See Horizons and layers.

Lamellae .................................................................................. 17

Limnic materials. See Organic soil material and Horizons

and layers.

Linear extensibility (LE) ......................................................... 17

Lithic contact ........................................................................... 25

Lithologic discontinuities ........................................................ 17

Luvihemists ........................................................................... 156

M

M horizons or layers. See Horizons and layers.

Marl. See Organic soil material.

Melanaquands.......................................................................... 79

Melanic epipedon ...................................................................... 7

Melanocryands ........................................................................ 83

Melanoxerands ........................................................................ 96

Melanudands ........................................................................... 90

Mesic temperature regime. See Soil temperature

regimes.

Mineral analyses .................................................................... 320

Mineral soil material.................................................................. 3

Mineral soils .............................................................................. 4

Mineralogy classes for Histosols and Histels ........................ 307

Mineralogy classes for mineral soils ..................................... 301

Mollic epipedon ......................................................................... 7

Mollisols ................................................................................ 191

Molliturbels ........................................................................... 150

Mollorthels ............................................................................ 147

N

n value ..................................................................................... 18

Natralbolls ............................................................................. 193

Natraqualfs .............................................................................. 43

Natraquerts ............................................................................ 286

Natraquolls ............................................................................ 196

Natrargids .............................................................................. 102

Natric horizon .......................................................................... 12

Natricryolls ............................................................................ 200

Natridurids ............................................................................. 117

Natrigypsids ........................................................................... 120

Natrixeralfs .............................................................................. 74

Natrixerolls ............................................................................ 232
Index 329

Natrudalfs ................................................................................ 56

Natrudolls .............................................................................. 207

Natrustalfs................................................................................ 65

Natrustolls.............................................................................. 220

Normal years ........................................................................... 26

O

O horizons or layers. See Horizons and layers.

Ochric epipedon ........................................................................ 8

Organic soil material ................................................................. 3

Fibers ................................................................................... 20

Fibric soil materials ............................................................. 21

Hemic soil materials ............................................................ 21

Humilluvic material ............................................................. 21

Limnic materials .................................................................. 22

Coprogenous earth........................................................... 22

Diatomaceous earth ......................................................... 22

Marl ................................................................................. 22

Sapric soil materials ............................................................ 21

Organic soils .............................................................................. 4

Orthels ................................................................................... 144

Orthents ................................................................................. 133

Orthods .................................................................................. 256

Ortstein .................................................................................... 13

Oxic horizon ............................................................................ 13

Oxisols ................................................................................... 235

P

Paleaquults ............................................................................. 264

Paleargids............................................................................... 104

Palecryalfs ............................................................................... 47

Palecryolls ............................................................................. 200

Palehumults ........................................................................... 267

Paleudalfs ................................................................................ 57

Paleudolls .............................................................................. 208

Paleudults .............................................................................. 273

Paleustalfs ................................................................................ 67

Paleustolls .............................................................................. 222

Paleustults .............................................................................. 279

Palexeralfs ............................................................................... 74

Palexerolls ............................................................................. 232

Palexerults ............................................................................. 280

Paralithic contact ..................................................................... 25

Paralithic materials .................................................................. 25

Particle-size classes for Histosols and Histels ....................... 306

Particle-size classes for mineral soils .................................... 295

Permafrost ............................................................................... 25

Permanent cracks (classes) in mineral soils .......................... 306

Perox ...................................................................................... 236

Petraquepts ............................................................................ 165

Petroargids............................................................................. 105

Petrocalcic horizon .................................................................. 13

Petrocalcids ........................................................................... 107

Petrocambids ......................................................................... 111

Petrocryids ............................................................................. 114

Petroferric contact ................................................................... 19

Petrogypsic horizon ................................................................. 13

Petrogypsids .......................................................................... 121

Physical analyses ................................................................... 317

Placaquands ............................................................................. 80

Placaquods............................................................................. 253

Placic horizon .......................................................................... 14

Placocryods ........................................................................... 255

Placohumods ......................................................................... 256

Placorthods ............................................................................ 259

Placudands............................................................................... 92

Plagganthrepts ....................................................................... 159

Plaggen epipedon ...................................................................... 8

Plinthaqualfs ............................................................................ 43

Plinthaquox ............................................................................ 236

Plinthaquults .......................................................................... 265

Plinthite.................................................................................... 19

Plinthohumults....................................................................... 268

Plinthoxeralfs ........................................................................... 76

Plinthudults ............................................................................ 275

Plinthustalfs ............................................................................. 70

Plinthustults ........................................................................... 279

Prime symbol in horizon designators .................................... 316

Psammaquents ....................................................................... 126

Psamments ............................................................................. 139

Psammorthels ........................................................................ 147

Psammoturbels ...................................................................... 150

Q

Quartzipsamments ................................................................. 139

R

R layers. See Horizons and layers.

Ratio, 15 kPa water to clay .................................................... 298

Ratio, CEC to clay ................................................................. 303

Reaction classes for Histosols and Histels ............................ 308

Rendolls ................................................................................. 201

Resistant minerals.................................................................... 19

Rhodoxeralfs ........................................................................... 76

Rhodudalfs............................................................................... 59

Rhodudults............................................................................. 275

Rhodustalfs .............................................................................. 70

Rhodustults ............................................................................ 279

Rock fragments...................................................................... 295

Rock structure............................................................................ 5
330 Keys to Soil Taxonomy

Root-limiting layer ................................................................ 296

Rounding ................................................................................. 31

Rupture-resistance classes for mineral soils .......................... 305

S

Salaquerts .............................................................................. 286

Salic horizon ............................................................................ 14

Salicryids ............................................................................... 115

Salids ..................................................................................... 122

Salitorrerts ............................................................................. 288

Salusterts................................................................................ 292

Sapric soil materials. See Organic soil material.

Sapristels................................................................................ 144

Saprists .................................................................................. 156

Series control section............................................................. 308

Series differentiae within a family ........................................ 308

Slickensides ............................................................................. 19

Soil ............................................................................................. 1

Soil color, water state criteria .................................................. 31

Soil depth classes for Histosols and Histels .......................... 308

Soil depth classes for mineral soils ....................................... 305

Soil moisture regimes .............................................................. 26

Aquic ................................................................................... 26

Aridic and torric .................................................................. 27

Udic ..................................................................................... 27

Ustic ..................................................................................... 27

Xeric .................................................................................... 27

Soil temperature classes for Histosols and Histels ................ 308

Soil temperature classes for mineral soils ............................. 304

Soil temperature regimes ......................................................... 28

Cryic .................................................................................... 28

Frigid ................................................................................... 28

Hyperthermic ....................................................................... 28

Isofrigid ............................................................................... 28

Isohyperthermic ................................................................... 28

Isomesic ............................................................................... 28

Isothermic ............................................................................ 28

Mesic ................................................................................... 28

Thermic................................................................................ 28

Sombric horizon ...................................................................... 14

Sombrihumults ...................................................................... 268

Sombriperox .......................................................................... 240

Sombriudox ........................................................................... 245

Sombriustox........................................................................... 249

Sphagnofibrists ...................................................................... 154

Spodic horizon ......................................................................... 14

Spodic materials ...................................................................... 19

Spodosols............................................................................... 251

Strongly contrasting particle-size classes .............................. 299

Subsurface tier ......................................................................... 23

Suffix symbols in horizon designators .................................. 313

Conventions for using letter suffixes ................................. 315

Vertical subdivision ........................................................... 315

Sulfaquents ............................................................................ 127

Sulfaquepts ............................................................................ 165

Sulfaquerts............................................................................. 287

Sulfidic materials..................................................................... 28

Sulfihemists ........................................................................... 156

Sulfisaprists ........................................................................... 157

Sulfohemists .......................................................................... 156

Sulfosaprists .......................................................................... 157

Sulfudepts .............................................................................. 177

Sulfuric horizon ....................................................................... 29

Surface tier............................................................................... 22

T

Thermic temperature regime. See Soil temperature

regimes.

Torrands ................................................................................... 84

Torrerts .................................................................................. 287

Torriarents .............................................................................. 127

Torric moisture regime. See Soil moisture regimes.

Torrifluvents .......................................................................... 129

Torrifolists ............................................................................. 155

Torriorthents .......................................................................... 134

Torripsamments ..................................................................... 140

Torrox .................................................................................... 240

Transitional and combination horizons ................................. 312

Turbels ................................................................................... 148

U

Udalfs ...................................................................................... 47

Udands ..................................................................................... 85

Udarents ................................................................................. 127

Udepts .................................................................................... 172

Uderts .................................................................................... 289

Udic moisture regime. See Soil moisture regimes.

Udifluvents ............................................................................ 130

Udifolists ............................................................................... 155

Udipsamments ....................................................................... 141

Udivitrands .............................................................................. 94

Udolls .................................................................................... 201

Udorthents ............................................................................. 136

Udox ...................................................................................... 241

Udults .................................................................................... 268

Ultisols ................................................................................... 261

Umbraquults .......................................................................... 265

Umbric epipedon ....................................................................... 8

Umbriturbels .......................................................................... 150

Umbrorthels........................................................................... 148

Ustalfs ...................................................................................... 59

Ustands .................................................................................... 92

Ustarents ................................................................................ 127

Ustepts ................................................................................... 177
Index 331

Usterts .................................................................................... 290

Ustic moisture regime. See Soil moisture regimes.

Ustifluvents............................................................................ 131

Ustifolists ............................................................................... 155

Ustipsamments ...................................................................... 141

Ustivitrands .............................................................................. 94

Ustolls .................................................................................... 209

Ustorthents ............................................................................. 136

Ustox ..................................................................................... 245

Ustults .................................................................................... 276

V

Vermaqualfs............................................................................. 43

Vermaquepts .......................................................................... 165

Vermudolls............................................................................. 208

Vermustolls ............................................................................ 224

Vertisols ................................................................................. 283

Vitrands.................................................................................... 93

Vitraquands.............................................................................. 80

Vitricryands ............................................................................. 83

Vitrigelands.............................................................................. 84

Vitritorrands............................................................................. 85

Vitrixerands ............................................................................. 96

Volcanic glass .......................................................................... 20

W

W layers. See Horizons and layers.

Weatherable minerals .............................................................. 20

X

Xeralfs ..................................................................................... 71

Xerands .................................................................................... 95

Xerarents ............................................................................... 128

Xerepts ................................................................................... 184

Xererts ................................................................................... 293

Xeric moisture regime. See Soil moisture regimes.

Xerofluvents .......................................................................... 132

Xerolls ................................................................................... 224

Xeropsamments ..................................................................... 142

Xerorthents ............................................................................ 138

Xerults ................................................................................... 279
332

S

O

I

D

I

F

D

I

A

I

I

D

E

The Soils That We Classify

Differentiae for Mineral Soils and Organic Soils

A

L

F

A

N

D

A

R

I

E

N

T

G

E

L

H

I

S

I

N

C

M

O

L

O

X

I

S

P

O

U

L

T

V

E

R

F

A

M

H

O

R

Horizons and Characteristics Diagnostic for the Higher Categories

Andisols

Identification of the Taxonomic Class of a Soil

Designations for Horizons and Layers

Family and Series Differentiae and Names

Vertisols

Ultisols

Spodosols

Oxisols

Mollisols

Inceptisols

Histosols

Gelisols

Entisols

Aridisols

Alfisols
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