In cooperation with

the Oklahoma Agricultural

Experiment Station

and the

Oklahoma Conservation

Committee

United States

Department of

Agriculture

Natural

Resources

Conservation

Service

Supplement to the

Soil Survey of

Comanche

County,

Oklahoma

i

How To Use This

Soil Survey Supplement

This document, in conjunction with the Web Soil Survey, supplements the Soil

Survey of Comanche County, Oklahoma, published in 1967. Find a map of your area

of interest on the Web Soil Survey at http://websoilsurvey.nrcs.usda.gov. Note the

map unit symbols in the area. Turn to the Contents in this supplement. The Contents

lists the map units by symbol and name and shows the page where each map unit is

described. Also see the Contents for sections of this publication that may address

your specific needs.

Advancements in technology and increases in the intensity and variety of land

uses have produced a need for updated soils information. In preparation for this

publication, the correlation for the Soil Survey of Comanche County was amended in

February 1997, January 2004, and March 2006. This publication and the Web Soil

Survey include the recorrelated map unit legend and updated information regarding

major soil properties and the use and management of the soils. In some cases, the

name of the map unit and the name of the soil series have changed from the first

publication. The map unit symbols and map delineations have not changed.

Web Soil Survey

The latest detailed soil maps and updated tabular data, including soil

properties and interpretations, are available on the Web Soil Survey at

http://websoilsurvey.nrcs.usda.gov.

Archived Soil Survey

Comprehensive descriptions of the detailed soil map units and additional

information about the soils in the survey area are archived in the original Soil Survey

of Comanche County, Oklahoma. Archived soil surveys are available from many

libraries, from the local office of the Natural Resources Conservation Service, and

from the Comanche County Conservation District in Lawton, Oklahoma.
ii

This document is a publication of the National Cooperative Soil Survey, a joint

effort of the United States Department of Agriculture and other Federal agencies,

State agencies including the Agricultural Experiment Stations, and local agencies.

The Natural Resources Conservation Service (formerly the Soil Conservation

Service) has leadership for the Federal part of the National Cooperative Soil Survey.

Major fieldwork for the Soil Survey of Comanche County, Oklahoma, was

completed in 1963. Soil names and descriptions were approved in 1965 and were

revised in 1997. Unless otherwise indicated, statements in this publication refer to

conditions in the survey area in 1997. The maps for the survey were recompiled

utilizing photographic imagery at 1:24,000 and rectified to 1995 digital

orthophotography for SSURGO digitizing. The survey was made cooperatively by the

Natural Resources Conservation Service, the Oklahoma Agricultural Experiment

Station, and the Oklahoma Conservation Commission. It is part of the technical

assistance furnished to the Comanche County Conservation District.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its

programs and activities on the basis of race, color, national origin, age, disability, and

where applicable, sex, marital status, familial status, parental status, religion, sexual

orientation, genetic information, political beliefs, reprisal, or because all or a part of an

individual’s income is derived from any public assistance program. (Not all prohibited

bases apply to all programs.) Persons with disabilities who require alternative means

for communication of program information (Braille, large print, audiotape, etc.) should

contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a

complaint of discrimination write to USDA, Director, Office of Civil Rights, 1400

Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272

(voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and

employer.
iii

Contents

How To Use This Soil Survey Supplement ................................................................i

Contents...................................................................................................................... iii

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

How Soil Surveys Are Made ........................................................................................ 2

General Nature of the County ...................................................................................... 3

History ...................................................................................................................... 3

Transportation .......................................................................................................... 3

Relief and Drainage ................................................................................................. 3

Climate ..................................................................................................................... 4

Table 1.—Temperature and Precipitation ............................................................ 5

Table 2.—Freeze Dates in Spring and Fall ......................................................... 6

Table 3.—Growing Season ................................................................................. 6

Detailed Soil Map Units ............................................................................................. 7

Table 4.—Acreage and Proportionate Extent of the Soils ....................................... 9

Bk—Vernon-Clairemont complex, 0 to 12 percent slopes ..................................... 10

Br—Ashport soils, 0 to 1 percent slopes, frequently flooded .................................11

CoB—Stephenville fine sandy loam, 1 to 3 percent slopes ....................................11

CoC—Stephenville fine sandy loam, 3 to 5 percent slopes .................................. 12

CoC2—Stephenville fine sandy loam, 3 to 5 percent slopes, eroded ................... 13

CtD—Cornick-Acme-Rock outcrop complex, 5 to 12 percent slopes.................... 14

DAM—Large dam .................................................................................................. 15

DoED—Dougherty-Eufaula complex, 3 to 8 percent slopes ................................. 15

Es—Tillman and Vernon soils, 2 to 8 percent slopes, severely eroded ................ 16

Et—Zaneis and Stephenville soils, 2 to 8 percent slopes, severely eroded .......... 17

EuD—Eufaula fine sand, 5 to 12 percent slopes ................................................... 19

FaA—Foard silt loam, 0 to 1 percent slopes ......................................................... 19

FsA—Foard-Hinkle complex, 0 to 1 percent slopes .............................................. 20

FsB—Foard-Hinkle complex, 1 to 3 percent slopes .............................................. 21

FtB—Foard and Tillman soils, 1 to 3 percent slopes ............................................. 23

Gc—Brico-Rock outcrop complex, 5 to 40 percent slopes .................................... 24

Go—Granite outcrop ............................................................................................. 25

HoB—Hollister silt loam, 0 to 1 percent slopes ..................................................... 25

KnB3—Konawa loamy fine sand, 3 to 8 percent slopes, severely eroded............ 26

KoB—Konawa loamy fine sand, 1 to 3 percent slopes ......................................... 27

KoC—Konawa loamy fine sand, 3 to 5 percent slopes ......................................... 27

KoC2—Konawa loamy fine sand, 3 to 5 percent slopes, eroded .......................... 28

LaB—Lawton loam, 1 to 3 percent slopes ............................................................. 29

LaC—Lawton loam, 3 to 5 percent slopes ............................................................ 30

LaC2—Lawton loam, 3 to 5 percent slopes, eroded ............................................. 30

Lc—Lela clay, 0 to 1 percent slopes, occasionally flooded ................................... 31

LfC—Lawton-Foard complex, 3 to 5 percent slopes ............................................. 32

Lm—Somervell very cobbly loam, 8 to 45 percent slopes .................................... 33

LzD—Lucien-Grainola-Zaneis complex, 5 to 12 percent slopes ........................... 34

M-W—Miscellaneous water ................................................................................... 35
iv

Mc—Miller clay, 0 to 1 percent slopes, occasionally flooded ................................ 36

MnC—Minco loam, 3 to 8 percent slopes ............................................................. 36

NorB—Norge silt loam, 1 to 3 percent slopes ....................................................... 37

NorC—Norge silt loam, 3 to 5 percent slopes ....................................................... 38

NOTCOM—Area not surveyed, access denied ..................................................... 39

Pc—Ashport clay loam, 0 to 1 percent slopes, occasionally flooded .................... 39

PIT—Pits ................................................................................................................ 39

Po—Ashport loam, 0 to 1 percent slopes, occasionally flooded ........................... 40

Ps—Ashport-Oscar complex, 0 to 1 percent slopes, occasionally flooded ........... 41

QUA—Quarry ........................................................................................................ 42

Ro—Rock outcrop-Brico complex, 3 to 20 percent slopes .................................... 42

Sc—Hinkle loam, 0 to 3 percent slopes ................................................................ 43

SmA—Stamford clay, 1 to 3 percent slopes .......................................................... 44

St—Brico soils and Rock outcrop, 15 to 50 percent slopes .................................. 44

Ta—Kiti-Rock outcrop complex, 3 to 25 percent slopes ........................................ 45

TmC—Tillman clay loam, 3 to 5 percent slopes .................................................... 46

VaA—Vanoss loam, 0 to 1 percent slopes ............................................................ 47

VaB—Vanoss loam, 1 to 3 percent slopes ............................................................ 48

VeC—Vernon clay, 3 to 5 percent slopes .............................................................. 48

VeD—Vernon-Knoco complex, 5 to 12 percent slopes ......................................... 49

W—Water .............................................................................................................. 50

Wa—Waurika silt loam, 0 to 1 percent slopes ....................................................... 51

We—Tribbey fine sandy loam, 0 to 1 percent slopes, frequently flooded ............. 51

WhB—Windthorst sandy loam, 1 to 3 percent slopes ........................................... 52

WhC—Windthorst sandy loam, 3 to 5 percent slopes ........................................... 53

ZaB—Zaneis loam, 1 to 3 percent slopes ............................................................. 54

ZaC—Zaneis loam, 3 to 5 percent slopes ............................................................. 54

ZaC2—Zaneis loam, 3 to 5 percent slopes, eroded .............................................. 55

ZsB—Zaneis-Huska complex, 1 to 3 percent slopes ............................................ 56

Zv—Cyril fine sandy loam, 0 to 1 percent slopes, occasionally flooded ............... 57

Use and Management of the Soils.......................................................................... 59

Rangeland ............................................................................................................. 60

Similarity Index .................................................................................................. 61

Rangeland Management ................................................................................... 62

Ecological Site Descriptions .............................................................................. 63

Formation and Classification of the Soils ............................................................. 69

Formation of the Soils ............................................................................................ 69

Classification of the Soils....................................................................................... 69

Table 5.—Classification of the Soils .................................................................. 71

References ................................................................................................................ 73

Glossary .................................................................................................................... 75

Issued June 2007
v

This soil survey supplement contains information that can be used in conjunction

with the previously published soil survey and with online resources. It provides

valuable information for land-planning programs in Oklahoma. It contains predictions

of soil behavior for selected land uses. This supplement also highlights limitations

and hazards inherent in the soil, improvements needed to overcome the limitations,

and the impact of selected land uses on the environment.

Soil surveys are designed for many different users. Farmers, ranchers, foresters,

and agronomists can use a survey to evaluate the potential of the soil and the

management needed for maximum food and fiber production. Planners, community

officials, engineers, developers, builders, and home buyers can use a survey to plan

land use, select sites for construction, and identify special practices needed to ensure

proper performance. Conservationists, teachers, students, and specialists in

recreation, wildlife management, waste disposal, and pollution control can use a

survey to help them understand, protect, and enhance the environment.

Great differences in soil properties can occur within short distances. Some soils

are seasonally wet or subject to flooding. Some are shallow to bedrock. Some are too

unstable to be used as a foundation for buildings or roads. Clayey or wet soils are

poorly suited for use as septic tank absorption fields. A high water table makes a soil

very limited for basements or underground installations.

These and many other soil properties that affect land use are described in soil

surveys. Each soil in the survey area is described. Information on specific uses is

given for each soil. Help in using this publication and additional information are

available at the local office of the Natural Resources Conservation Service or the

Cooperative Extension Service.

Ronald L. Hilliard

State Conservationist

Natural Resources Conservation Service

Foreword

1

Fieldwork by Hubert L. Mobley and R.C. Brinlee,

Natural Resources Conservation Service

(formerly the Soil Conservation Service)

United States Department of Agriculture,

Natural Resources Conservation Service,

in cooperation with

the Oklahoma Agricultural Experiment Station and

the Oklahoma Conservation Commission

This supplement provides information to update the original soil survey of

Comanche County, Oklahoma, which was issued August 1967 (USDA, 1967). The

original tables and maps are not included in this document. Updated tables and

new digital maps on updated photography are available from the Web Soil Survey

at http://websoilsurvey.nrcs.usda.gov. The tables were generated from the NRCS

National Soil Information System (NASIS) and are also available from the NRCS

Soil Data Mart at http://soildatamart.nrcs.usda.gov.

Supplement to the Soil Survey of

Comanche County,

Oklahoma

Figure 1.—Location of Delaware County in Oklahoma.

COMANCHE COUNTY is in the southwestern part of Oklahoma. (fig. 1). It is bounded on

the north by Caddo and Kiowa Counties, on the south by Cotton County, on the east

by Grady and Stephens Counties, and on the west by Tillman and Kiowa Counties. It

has an area of 1,084 square miles, or 693,612 acres. Lawton, the county seat, is in

the central part of the county.

Agriculture and related services are important in Comanche County. The chief

source of income is from the sale of wheat, grain sorghum, cotton, alfalfa hay,

livestock, and related products. Oil and gas are also important. In 2002,

approximately 178,000 acres, or 26 percent of the county, was cultivated. The

county has about 3,600 acres of irrigated cropland and improved pasture. The
Supplement to the Soil Survey of Comanche County, Oklahoma

2

remaining 74 percent of the county is native range; nonirrigated, improved pasture;

and urban development.

How Soil Surveys Are Made

Soil surveys are made to provide information about the soils and miscellaneous

areas in the survey area. The information includes a description of the soils and

miscellaneous areas and their location and a discussion of their suitability, limitations,

and management for specified uses. Soil scientists observe the steepness, length,

and shape of the slopes; the general pattern of drainage; the kinds of crops and

native plants; and the kinds of bedrock. They dig many holes to study the soil profile,

which is the sequence of natural layers, or horizons, in a soil. The profile extends

from the surface down into the unconsolidated material in which the soil formed. The

unconsolidated material is devoid of roots and other living organisms and has not

been changed by other biological activity.

The soils and miscellaneous areas in a survey area are in an orderly pattern that is

related to the geology, landforms, relief, climate, and natural vegetation of the area.

Each kind of soil and miscellaneous area is associated with a particular kind or

segment of the landscape. By observing the soils and miscellaneous areas in a survey

area and relating their position to specific segments of the landscape, soil scientists

develop a concept, or model, of how the soils were formed. Thus, during mapping, this

model enables the soil scientists to predict with a considerable degree of accuracy the

kind of soil or miscellaneous area at a specific location on the landscape.

Individual soils on the landscape commonly merge into one another as their

characteristics gradually change. To construct an accurate map, however, soil

scientists must determine the boundaries between the soils. They can observe only a

limited number of soil profiles. Nevertheless, these observations, supplemented by an

understanding of the soil-vegetation-landscape relationship, are sufficient to verify

predictions of the kinds of soil in an area and to determine the boundaries.

Soil scientists record the characteristics of the soil profiles that they study. They

note color, texture, size, and shape of soil aggregates, kind and amount of rock

fragments, distribution of plant roots, reaction, and other features that enable them to

identify soils. After describing the soils in a survey area and determining their

properties, the soil scientists assign the soils to taxonomic classes (units). Taxonomic

classes are concepts. Each taxonomic class has a set of soil characteristics with

precisely defined limits. The classes are used as a basis for comparison to classify

soils systematically. Soil taxonomy, the system of taxonomic classification used in the

United States, is based mainly on the kind and character of soil properties and the

arrangement of horizons within the profile. After the soil scientists classify and name

the soils in a survey area, they compare the individual soils with similar soils in the

same taxonomic class in other areas so that they could confirm data and assemble

additional data based on experience and research.

While a soil survey is in progress, samples of some of the soils in the area

generally are collected for laboratory analyses and for engineering tests. Soil

scientists interpret the data from these analyses and tests as well as the fieldobserved characteristics and the soil properties to determine the expected behavior

of the soils under different uses. Interpretations for all of the soils are field tested

through observation of the soils in different uses and under different levels of

management. Some interpretations are modified to fit local conditions, and some new

interpretations are developed to meet local needs. Data are assembled from other

sources, such as research information, production records, and field experience of

specialists. For example, data on crop yields under defined levels of management are

assembled from farm records and from field or plot experiments on the same kinds of

soil.
Supplement to the Soil Survey of Comanche County, Oklahoma

3

Predictions about soil behavior are based not only on soil properties but also on

such variables as climate and biological activity. Soil conditions are predictable over

long periods of time, but they are not predictable from year to year. For example, soil

scientists can predict with a fairly high degree of accuracy that a given soil will have a

high water table within certain depths in most years, but they cannot predict that a

high water table will always be at a specific level in the soil on a specific date.

After soil scientists locate and identify the significant natural bodies of soil in a

survey area, they draw the boundaries of these bodies on aerial photographs and

identified each as a specific map unit. Aerial photographs show trees, buildings,

fields, roads, and rivers, all of which help in locating boundaries accurately.

The descriptions, names, and delineations of the soils in a survey area do not

always fully agree with those of the soils in adjacent survey areas. Differences are

the result of a better knowledge of soils, modifications in series concepts, or

variations in the intensity of mapping or in the extent of the soils in the survey areas.

General Nature of the County

This section provides information that may be useful to persons not familiar with

Comanche County. It briefly describes subjects of general interest, including history,

transportation, relief, drainage, and climate.

History

The area that is now Comanche County was included in the Louisiana Purchase

and was acquired by the United States from France in 1803. The area became a part

of Indian Territory and was originally a part of the Kiowa, Comanche, and Apache

Reservation. Fort Sill was established by General Phillip H. Sheridan as a cavalry fort

in 1869. It is now headquarters of the U.S. Army Field Artillery Center and School. It

covers approximately 94,000 acres.

On August 6, 1901, Comanche County was opened for homesteading by lottery.

The Wichita Mountains Wildlife Refuge was also created in 1901. It covers over

59,000 acres and provides habitat for large, native grazing animals, such as

American Bison, Rocky Mountain Elk, Texas longhorn cattle, and white-tailed deer.

The town of Lawton was also established in 1901. It is the county seat and has a

population of approximately 90,000. The current population of the county is over

110,000.

Transportation

The county is served by an airport facility at Lawton. It is also served by Interstate

44, which runs north and south, by three Federal highways, by seven State highways,

and by numerous county roads. Some of the county roads have been surfaced and

are suitable for all-weather travel.

Relief and Drainage

Comanche County is in the Central Rolling Red Plains, Central Rolling Red

Prairies, and Wichita Mountains major land resource areas. The county is drained

mostly by tributaries of the Red River. Small areas are drained by the Washita River

and its tributaries. The topography ranges from the nearly level flood plains along the

rivers to steep uplands associated with the Wichita Mountains. The general slope is

toward the southeast. Elevation ranges from about 1,000 feet where Cashe Creek

leaves the county to 2,479 feet at Mt. Pinchot in the northwestern part of the county.
Supplement to the Soil Survey of Comanche County, Oklahoma

4

Climate

The climate tables were created using data from the climate station at Lawton,

Oklahoma. Thunderstorm days, relative humidity, percent sunshine, and wind

information are estimated from the first order station at Wichita Falls, Texas.

The table “Temperature and Precipitation” gives data on temperature and

precipitation for the survey area as recorded at Lawton, Oklahoma, for the period

1971 to 2000. The table “Freeze Dates in Spring and Fall” shows probable dates of

the first freeze in fall and the last freeze in spring. The table “Growing Season”

provides data on the length of the growing season.

In winter, the average temperature is 40.9 degrees F and the average daily

minimum temperature is 28.6 degrees. The lowest temperature on record, which

occurred at Lawton on December 22, 1989, is -8 degrees. In summer, the average

temperature is 81.5 degrees and the average daily maximum temperature is 93.5

degrees. The highest temperature, which occurred at Lawton on June 28, 1994, is

114 degrees.

Growing degree days are shown in the table “Temperature and Precipitation.” They

are equivalent to “heat units.” During the month, growing degree days accumulate by

the amount that the average temperature each day exceeds a base temperature (50

degrees F). The normal monthly accumulation is used to schedule single or

successive plantings of a crop between the last freeze in spring and the first freeze in

fall.

The average annual total precipitation is about 31.72 inches at Lawton and 34

inches in the Witchita Mountains. Of the 31.7 inches of annual precipitation at

Lawton, about 22.9 inches, or 72 percent, usually falls in April through October. The

growing season for most crops falls within this period. The heaviest 1-day rainfall

during the period of record at Lawton was 6.25 inches on October 23, 1953.

Thunderstorms occur on about 48 days each year. Most occur between April and

August.

The average seasonal snowfall is 1.5 inches at Lawton and 3 inches in the

Witchita Mountains. The greatest snow depth at any one time during the period of

record at Lawton was 6 inches recorded on December 29, 1954. On an average, less

than 1 day per year has at least 1 inch of snow on the ground at the lower elevations.

About 2 to 3 days per year have some snow cover in the Wichita Mountains. The

heaviest 1-day snowfall on record at Lawton was 9 inches recorded on January 7,

1988.

The average relative humidity in mid-afternoon is about 55 percent in the winter,

and about 40 percent in midsummer. Humidity is higher at night, and the average at

dawn is about 80 percent year around. The sun shines 80 percent of the time

possible in summer and 60 percent in winter. The prevailing wind is from the north in

January and February and from the south from March through December. Average

wind speed is highest, 13 miles per hour, in March and April.
Supplement to the Soil Survey of Comanche County, Oklahoma

5

Table 1.--Temperature and Precipitation

[Recorded in the period 1971-2000 at Lawton, Oklahoma]

_____________________________________________________________________________________________________

 | |

 | Temperature | Precipitation

 |__________________________________________________|______________________________________

 | | | | 2 years in | | |2 years in 10|Average|

 Month | | | | 10 will have-- |Average | | will have-- | number|

 | | | |_________________| number | Avg. |_____________| of | Average

 |Average|Average|Average| Max. | Min. | of | | | | days |snowfall

 | daily | daily | | temp. | temp. | growing| | Less | More | with |

 |maximum|minimum| | higher | lower | degree | |than--|than--| 0.10 |

 | | | | than | than | days* | | | | inch |

___________|_______|_______|_______|________|________|________|_______|______|______|_______|________

 | °F | °F | °F | °F | °F | Units | In | In | In | | In

 | | | | | | | | | | |

January----| 51.0 | 26.1 | 38.6 | 76 | 4 | 12 | 1.15 | 0.14| 2.16| 2 | 0.9

February---| 56.0 | 30.8 | 43.4 | 82 | 6 | 46 | 1.58 | 0.32| 2.81| 2 | 0.5

March------| 65.0 | 39.8 | 52.4 | 90 | 19 | 152 | 2.56 | 0.99| 4.01| 4 | 0.0

April------| 73.7 | 48.6 | 61.2 | 92 | 30 | 341 | 2.94 | 1.15| 4.83| 4 | 0.0

May--------| 81.8 | 58.7 | 70.2 | 99 | 43 | 608 | 5.00 | 1.78| 8.34| 5 | 0.0

June-------| 90.0 | 66.9 | 78.5 | 105 | 53 | 827 | 4.01 | 1.94| 5.90| 5 | 0.0

July-------| 95.6 | 71.5 | 83.5 | 107 | 59 | 1,022 | 2.02 | 0.48| 3.24| 3 | 0.0

August-----| 94.8 | 70.2 | 82.5 | 105 | 58 | 988 | 2.38 | 0.72| 3.39| 3 | 0.0

September--| 86.3 | 62.1 | 74.2 | 103 | 41 | 704 | 3.27 | 1.12| 5.15| 4 | 0.0

October----| 75.9 | 50.6 | 63.3 | 96 | 31 | 407 | 3.28 | 0.89| 5.13| 4 | 0.0

November---| 62.1 | 37.8 | 50.0 | 84 | 19 | 109 | 1.79 | 0.41| 3.27| 3 | 0.0

December---| 52.3 | 28.9 | 40.6 | 76 | 8 | 18 | 1.74 | 0.47| 2.80| 3 | 0.1

 | | | | | | | | | | |

Yearly: | | | | | | | | | | |

 Average--| 73.7 | 49.3 | 61.5 | --- | --- | --- | --- | ---| ---| --- | ---

 Extreme--| 114 | -8 | --- | 109 | 1 | --- | --- | ---| ---| --- | ---

 Total----| --- | --- | --- | --- | --- | 5,233 | 31.72 | 23.28| 36.39| 42 | 1.5

 | | | | | | | | | | |

___________|_______|_______|_______|________|________|________|_______|______|______|_______|________

 * A growing degree day is a unit of heat available for plant growth. It can be calculated by

adding the maximum and minimum daily temperatures, dividing the sum by 2, and subtracting the

temperature below which growth is minimal for the principal crops in the area (50 degrees F).
Supplement to the Soil Survey of Comanche County, Oklahoma

6

Table 2.--Freeze Dates in Spring and Fall

[Recorded in the period 1971-2000 at Lawton, Oklahoma]

____________________________________________________________

 |

 | Temperature

 Probability |_________________________________________

 | 24 °F | 28 °F | 32 °F

 | or lower | or lower | or lower

__________________|_____________|_____________|_____________

 | | |

Last freezing | | |

 temperature | | |

 in spring: | | |

 | | |

 1 year in 10 | | |

 later than-- | Mar. 24 | Apr. 1 | Apr. 10

 | | |

 2 years in 10 | | |

 later than-- | Mar. 14 | Mar. 26 | Apr. 6

 | | |

 5 years in 10 | | |

 later than-- | Feb. 23 | Mar. 14 | Mar. 28

 | | |

First freezing | | |

 temperature | | |

 in fall: | | |

 | | |

 1 year in 10 | | |

 earlier than-- | Nov. 13 | Nov. 4 | Oct. 19

 | | |

 2 years in 10 | | |

 earlier than-- | Nov. 19 | Nov. 9 | Oct. 25

 | | |

 5 years in 10 | | |

 earlier than-- | Dec. 1 | Nov. 18 | Nov. 7

 | | |

__________________|_____________|_____________|_____________

Table 3.--Growing Season

[Recorded in the period 1971-2000 at Lawton,

 Oklahoma]

___________________________________________________

 |

 | Daily Minimum Temperature

 | During growing season

 Probability |____________________________________

 | Higher | Higher | Higher

 | than | than | than

 | 24 °F | 28 °F | 32 °F

______________|____________|___________|___________

 | Days | Days | Days

 | | |

9 years in 10 | 239 | 221 | 203

 | | |

8 years in 10 | 252 | 229 | 210

 | | |

5 years in 10 | 277 | 247 | 224

 | | |

2 years in 10 | 303 | 264 | 239

 | | |

1 year in 10 | 316 | 273 | 246

______________|____________|___________|___________
7

Detailed soil maps for the survey area are available online at

http://websoilsurvey.nrcs.usda.gov. The map units on the detailed soil maps

represent the soils and miscellaneous areas in the survey area. The map unit

descriptions in this section, along with the maps, can be used to determine the

suitability and potential of a unit for specific uses. They also can be used to plan

the management needed for those uses.

A map unit delineation on the detailed soil maps represents an area on the

landscape and consists of one or more soils or miscellaneous areas. A map unit is

identified and named according to the taxonomic classification of the dominant soils

or miscellaneous areas. Within a taxonomic class there are precisely defined limits

for the properties of the soils. On the landscape, however, the soils and

miscellaneous areas are natural phenomena, and they have the characteristic

variability of all natural phenomena. Thus, the range of some observed properties

may extend beyond the limits defined for a taxonomic class. Areas of soils of a single

taxonomic class rarely, if ever, are mapped without areas of minor components of

other taxonomic classes. Consequently, map units are made up of the soils or

miscellaneous areas for which they are named and some areas of included soils that

belong to other taxonomic classes.

Most included soils have properties similar to those of the dominant soil or soils in

the map unit, and thus they do not affect use and management. These are called

noncontrasting or similar inclusions. They may or may not be mentioned in the map

unit description. Other included soils and miscellaneous areas, however, have

properties and behavioral characteristics divergent enough to affect use or to require

different management. These are called contrasting, or dissimilar, inclusions. They

generally are in small areas and could not be mapped separately because of the

scale used. Some small areas of strongly contrasting soils or miscellaneous areas

are identified by a special symbol on the maps. The included areas of contrasting

soils or miscellaneous areas are mentioned in the map unit descriptions. A few

included areas may not have been observed, and consequently they are not

mentioned in the descriptions, especially where the pattern was so complex that it

was impractical to make enough observations to identify all the soils and

miscellaneous areas on the landscape.

The presence of included areas in a map unit in no way diminishes the usefulness

or accuracy of the data. The objective of mapping is not to delineate pure taxonomic

classes but rather to separate the landscape into segments that have similar use and

management requirements. The delineation of such landscape segments on the map

provides sufficient information for the development of resource plans, but if intensive

use of small areas is planned, onsite investigation is needed to define and locate the

soils and miscellaneous areas.

An identifying symbol precedes the map unit name in the map unit descriptions.

Each description includes general facts about the unit.

Soils that have profiles that are almost alike make up a soil series. Except for

differences in texture of the surface layer or of the underlying layers, all the soils of

Detailed Soil Map Units
Supplement to the Soil Survey of Comanche County, Oklahoma

8

a series have major horizons that are similar in composition, thickness, and

arrangement.

Soils of one series can differ in texture of the surface layer or of the underlying

layers. They also can differ in slope, stoniness, salinity, wetness, degree of erosion,

and other characteristics that affect their use. On the basis of such differences, a soil

series is divided into soil phases. Most of the areas shown on the detailed soil maps

are phases of soil series. The name of a soil phase commonly indicates a feature that

affects use or management. For example, Ashport loam, 0 to 1 percent slopes,

occasionally flooded, is a phase of the Ashport series.

Some map units are made up of two or more major soils or miscellaneous areas.

These map units are complexes, associations, or undifferentiated groups.

A complex consists of two or more soils or miscellaneous areas in such an intricate

pattern or in such small areas that they cannot be shown separately on the maps.

The pattern and proportion of the soils or miscellaneous areas are somewhat similar

in all areas. Foard-Hinkle complex,1 to 3 percent slopes, is an example.

An undifferentiated group is made up of two or more soils or miscellaneous areas

that could be mapped individually but are mapped as one unit because similar

interpretations can be made for use and management. The pattern and proportion of

the soils or miscellaneous areas in a mapped area are not uniform. An area can be

made up of only one of the major soils or miscellaneous areas, or it can be made up

of all of them. Foard and Tillman soils, 1 to 3 percent slopes, is an undifferentiated

group in this survey area.

This survey includes miscellaneous areas. Such areas have little or no soil

material and support little or no vegetation. Pits is an example.

The table "Acreage and Proportionate Extent of the Soils" gives the acreage and

proportionate extent of each map unit. The Glossary defines many of the terms used

in describing the soils or miscellaneous areas.
Supplement to the Soil Survey of Comanche County, Oklahoma

9

Table 4.--Acreage and Proportionate Extent of the Soils

_______________________________________________________________________________________________________

 | | |

 Map | Soil name | Acres |Percent

symbol | | |

_______|_________________________________________________________________________|____________|________

 | | |

Bk |Vernon-Clairemont complex, 0 to 12 percent slopes------------------------| 14,219 | 2.0

Br |Ashport soils, 0 to 1 percent slopes, frequently flooded-----------------| 10,851 | 1.6

CoB |Stephenville fine sandy loam, 1 to 3 percent slopes----------------------| 3,161 | 0.5

CoC |Stephenville fine sandy loam, 3 to 5 percent slopes----------------------| 2,478 | 0.4

CoC2 |Stephenville fine sandy loam, 3 to 5 percent slopes, eroded--------------| 7,880 | 1.1

CtD |Cornick-Acme-Rock outcrop complex, 5 to 12 percent slopes----------------| 484 | *

DAM |Large dam----------------------------------------------------------------| 47 | *

DoED |Dougherty-Eufaula complex, 3 to 8 percent slopes-------------------------| 232 | *

Es |Tillman and Vernon soils, 2 to 8 percent slopes, severely eroded---------| 6,544 | 0.9

Et |Zaneis and Stephenville soils, 2 to 8 percent slopes, severely eroded----| 17,385 | 2.5

EuD |Eufaula fine sand, 5 to 12 percent slopes--------------------------------| 1,491 | 0.2

FaA |Foard silt loam, 0 to 1 percent slopes-----------------------------------| 15,052 | 2.2

FsA |Foard-Hinkle complex, 0 to 1 percent slopes------------------------------| 4,190 | 0.6

FsB |Foard-Hinkle complex, 1 to 3 percent slopes------------------------------| 24,011 | 3.5

FtB |Foard and Tillman soils, 1 to 3 percent slopes---------------------------| 80,044 | 11.5

Gc |Brico-Rock outcrop complex, 5 to 40 percent slopes-----------------------| 20,354 | 2.9

Go |Granite outcrop----------------------------------------------------------| 4,307 | 0.6

HoB |Hollister silt loam, 0 to 1 percent slopes-------------------------------| 1,597 | 0.2

KnB3 |Konawa loamy fine sand, 3 to 8 percent slopes, severely eroded-----------| 4,340 | 0.6

KoB |Konawa loamy fine sand, 1 to 3 percent slopes----------------------------| 1,638 | 0.2

KoC |Konawa loamy fine sand, 3 to 5 percent slopes----------------------------| 5,696 | 0.8

KoC2 |Konawa loamy fine sand, 3 to 5 percent slopes, eroded--------------------| 3,978 | 0.6

LaB |Lawton loam, 1 to 3 percent slopes---------------------------------------| 14,715 | 2.1

LaC |Lawton loam, 3 to 5 percent slopes---------------------------------------| 10,580 | 1.5

LaC2 |Lawton loam, 3 to 5 percent slopes, eroded-------------------------------| 3,339 | 0.5

Lc |Lela clay, 0 to 1 percent slopes, occasionally flooded-------------------| 769 | 0.1

LfC |Lawton-Foard complex, 3 to 5 percent slopes------------------------------| 1,704 | 0.2

Lm |Somervell very cobbly loam, 8 to 45 percent slopes-----------------------| 7,413 | 1.1

LzD |Lucien-Grainola-Zaneis complex, 5 to 12 percent slopes-------------------| 29,777 | 4.3

M-W |Miscellaneous water------------------------------------------------------| 265 | *

Mc |Miller clay, 0 to 1 percent slopes, occasionally flooded-----------------| 658 | *

MnC |Minco loam, 3 to 8 percent slopes----------------------------------------| 7,816 | 1.1

NorB |Norge silt loam, 1 to 3 percent slopes-----------------------------------| 229 | *

NorC |Norge silt loam, 3 to 5 percent slopes-----------------------------------| 192 | *

NOTCOM |Area not surveyed, access denied-----------------------------------------| 93,709 | 13.5

Pc |Ashport clay loam, 0 to 1 percent slopes, occasionally flooded-----------| 29,146 | 4.2

PIT |Pits---------------------------------------------------------------------| 138 | *

Po |Ashport loam, 0 to 1 percent slopes, occasionally flooded----------------| 23,827 | 3.4

Ps |Ashport-Oscar complex, 0 to 1 percent slopes, occasionally flooded-------| 9,232 | 1.3

QUA |Quarry-------------------------------------------------------------------| 412 | *

Ro |Rock outcrop-Brico complex, 3 to 20 percent slopes-----------------------| 17,731 | 2.6

Sc |Hinkle loam, 0 to 3 percent slopes---------------------------------------| 4,872 | 0.7

SmA |Stamford clay, 1 to 3 percent slopes-------------------------------------| 1,944 | 0.3

St |Brico soils and Rock outcrop, 15 to 50 percent slopes--------------------| 41,746 | 6.0

Ta |Kiti-Rock outcrop complex, 3 to 25 percent slopes------------------------| 12,750 | 1.8

TmC |Tillman clay loam, 3 to 5 percent slopes---------------------------------| 8,751 | 1.3

VaA |Vanoss loam, 0 to 1 percent slopes---------------------------------------| 1,253 | 0.2

VaB |Vanoss loam, 1 to 3 percent slopes---------------------------------------| 1,153 | 0.2

VeC |Vernon clay, 3 to 5 percent slopes---------------------------------------| 16,979 | 2.4

VeD |Vernon-Knoco complex, 5 to 12 percent slopes-----------------------------| 37,015 | 5.3

W |Water--------------------------------------------------------------------| 11,464 | 1.7

Wa |Waurika silt loam, 0 to 1 percent slopes---------------------------------| 738 | 0.1

We |Tribbey fine sandy loam, 0 to 1 percent slopes, frequently flooded-------| 1,670 | 0.2

WhB |Windthorst sandy loam, 1 to 3 percent slopes-----------------------------| 2,785 | 0.4

WhC |Windthorst sandy loam, 3 to 5 percent slopes-----------------------------| 4,457 | 0.6

ZaB |Zaneis loam, 1 to 3 percent slopes---------------------------------------| 9,080 | 1.3

ZaC |Zaneis loam, 3 to 5 percent slopes---------------------------------------| 6,850 | 1.0

ZaC2 |Zaneis loam, 3 to 5 percent slopes, eroded-------------------------------| 14,545 | 2.1

ZsB |Zaneis-Huska complex, 1 to 3 percent slopes------------------------------| 32,593 | 4.7

Zv |Cyril fine sandy loam, 0 to 1 percent slopes, occasionally flooded-------| 1,336 | 0.2

 | |____________|________

 | Total---------------------------------------------------------------| 693,612 | 100.0

_______|_________________________________________________________________________|____________|________

 * Less than 0.1 percent.
Supplement to the Soil Survey of Comanche County, Oklahoma

10

Bk—Vernon-Clairemont complex, 0 to 12 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 700 to 2,500 feet

Mean annual precipitation: 20 to 40 inches

Mean annual air temperature: 57 to 66 degrees F

Frost-free period: 190 to 240 days

Major Component Description

Vernon

Extent: 50 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Calcareous, clayey residuum weathered from claystone

Slope: 5 to 12 percent

Surface runoff class: Very high

Soil depth: 17 to 40 inches to bedrock (densic)

Depth to paralithic bedrock: 40 to 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 2.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R078CY031OK, Clay Prairie (South) PE 32-44

Typical profile:

A—0 to 4 inches; clay

Bk—4 to 17 inches; clay

Cd—17 to 50 inches; bedrock

Cr—50 to 80 inches; bedrock

Clairemont

Extent: 20 percent of the map unit

Geomorphic setting: Flood plains in river valleys

Parent material: Calcareous, silty alluvium

Slope: 0 to 1 percent

Surface runoff class: Negligible

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 11.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: Frequent

Ponding: None

Land capability classification, nonirrigated: 5w

Ecological site number and name: R078CY050OK, Loamy Bottomland PE 32-44

Typical profile:

A—0 to 18 inches; silt loam

C—18 to 80 inches; silty clay loam
Supplement to the Soil Survey of Comanche County, Oklahoma

11

Additional Components

Ashport soils: 9 percent of the map unit

Knoco soils: 9 percent of the map unit

Rock outcrop: 7 percent of the map unit

Wheatwood soils: 5 percent of the map unit

Br—Ashport soils, 0 to 1 percent slopes, frequently

flooded

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 2,250 feet

Mean annual precipitation: 20 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Ashport

Extent: 70 percent of the map unit

Geomorphic setting: Flood plains in river valleys

Parent material: Fine-silty alluvium

Slope: 0 to 1 percent

Surface runoff class: Negligible

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 11.8 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: Frequent

Ponding: None

Land capability classification, nonirrigated: 5w

Ecological site number and name: R080AY050OK, Loamy Bottomland PE 44-64

Typical profile:

A—0 to 18 inches; loam

C—18 to 80 inches; loam

Additional Components

Port soils: 9 percent of the map unit

Clairemont soils: 5 percent of the map unit

Easpur soils: 5 percent of the map unit

Wheatwood soils: 5 percent of the map unit

Yahola soils: 5 percent of the map unit

Retrop soils: 1 percent of the map unit

CoB—Stephenville fine sandy loam, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 84A

Elevation: 500 to 1,500 feet

Mean annual precipitation: 30 to 40 inches
Supplement to the Soil Survey of Comanche County, Oklahoma

12

Mean annual air temperature: 58 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Stephenville

Extent: 85 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Shoulders

Parent material: Loamy residuum weathered from sandstone

Slope: 1 to 3 percent

Surface runoff class: Low

Soil depth: 20 to 40 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 5.6 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R084AY075OK, Sandy Savannah PE 44-64

Typical profile:

A—0 to 10 inches; fine sandy loam

Bt—10 to 35 inches; sandy clay loam

Cr—35 to 40 inches; bedrock

Additional Components

Konawa soils: 10 percent of the map unit

Rock outcrop: 5 percent of the map unit

CoC—Stephenville fine sandy loam, 3 to 5 percent slopes

Map Unit Setting

Major land resource area: 84A

Elevation: 500 to 1,500 feet

Mean annual precipitation: 30 to 40 inches

Mean annual air temperature: 58 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Stephenville

Extent: 85 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy residuum weathered from sandstone

Slope: 3 to 5 percent

Surface runoff class: Low

Soil depth: 20 to 40 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained
Supplement to the Soil Survey of Comanche County, Oklahoma

13

Available water capacity: About 5.6 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R084AY075OK, Sandy Savannah PE 44-64

Typical profile:

A—0 to 10 inches; fine sandy loam

Bt—10 to 35 inches; sandy clay loam

Cr—35 to 40 inches; bedrock

Additional Components

Konawa soils: 10 percent of the map unit

Rock outcrop: 5 percent of the map unit

CoC2—Stephenville fine sandy loam, 3 to 5 percent

slopes, eroded

Map Unit Setting

Major land resource area: 84A

Elevation: 500 to 1,500 feet

Mean annual precipitation: 30 to 40 inches

Mean annual air temperature: 58 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Stephenville

Extent: 85 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy residuum weathered from sandstone

Slope: 3 to 5 percent

Surface runoff class: Low

Soil depth: 20 to 40 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 5.6 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R084AY876OK, Eroded Sandy Savannah PE

48-64

Typical profile:

A—0 to 10 inches; fine sandy loam

Bt—10 to 35 inches; sandy clay loam

Cr—35 to 40 inches; bedrock

Additional Components

Konawa soils: 10 percent of the map unit

Rock outcrop: 5 percent of the map unit
Supplement to the Soil Survey of Comanche County, Oklahoma

14

CtD—Cornick-Acme-Rock outcrop complex, 5 to 12

percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 500 to 2,500 feet

Mean annual precipitation: 20 to 48 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 190 to 240 days

Major Component Description

Cornick

Extent: 45 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy residuum weathered from gypsum

Slope: 5 to 12 percent

Surface runoff class: Very high

Soil depth: 5 to 10 inches to bedrock (lithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 1.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 7s

Ecological site number and name: R078CY038OK, Gyp PE 32-44

Typical profile:

A—0 to 6 inches; loam

Cr1—6 to 10 inches; bedrock

Cr2—10 to 18 inches; bedrock

Acme

Extent: 35 percent of the map unit

Geomorphic setting: Paleoterraces on alluvial plains

Position on the landform: Risers

Parent material: Loamy alluvium

Slope: 3 to 5 percent

Surface runoff class: Medium

Soil depth: 10 to 20 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 3.0 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 4s

Ecological site number and name: R078CY084OK, Shallow Prairie (South) PE 32-44

Typical profile:

A—0 to 15 inches; loam

Cr—15 to 36 inches; bedrock
Supplement to the Soil Survey of Comanche County, Oklahoma

15

Rock outcrop

Extent: 20 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Slope: 5 to 12 percent

Surface runoff class: Very high

Land capability classification, nonirrigated: 8s

DAM—Large dam

Map Unit Setting

Major land resource area: 78C

Elevation: 700 to 2,000 feet

Mean annual precipitation: 26 to 30 inches

Mean annual air temperature: 59 to 63 degrees F

Frost-free period: 200 to 220 days

Major Component Description

Large dam

Extent: 100 percent of the map unit

Geomorphic setting: Artificial levees

Parent material: Mine spoil or earthy fill

Slope: 0 to 45 percent

Surface runoff class: Very high

Land capability classification, nonirrigated: 8

DoED—Dougherty-Eufaula complex, 3 to 8 percent slopes

Map Unit Setting

Major land resource area: 84A

Elevation: 500 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 190 to 230 days

Major Component Description

Dougherty

Extent: 40 percent of the map unit

Geomorphic setting: Dunes in dune fields on sandhills in valleys

Parent material: Sandy and loamy alluvium and/or sandy eolian deposits

Slope: 3 to 8 percent

Surface runoff class: Low

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 6.5 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 4e

Ecological site number and name: R084AY018OK, Deep Sand Savannah PE 48-64
Supplement to the Soil Survey of Comanche County, Oklahoma

16

Typical profile:

A—0 to 9 inches; loamy fine sand

E—9 to 27 inches; fine sand

Bt—27 to 48 inches; sandy clay loam

BC—48 to 64 inches; fine sandy loam

C—64 to 80 inches; fine sandy loam

Eufaula

Extent: 20 percent of the map unit

Geomorphic setting: Dunes in dune fields on terraces in valleys

Parent material: Eolian sands

Slope: 3 to 8 percent

Surface runoff class: Very low

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Rapid

Slowest permeability class within a depth of 80 inches: Rapid

Drainage class: Somewhat excessively drained

Available water capacity: About 5.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 4e

Ecological site number and name: R084AY018OK, Deep Sand Savannah PE 48-64

Typical profile:

A—0 to 10 inches; fine sand

E1—10 to 45 inches; fine sand

E2 and Bt—45 to 80 inches; fine sand

Additional Components

Bathel soils: 10 percent of the map unit

Derby soils: 10 percent of the map unit

Konawa soils: 10 percent of the map unit

Meno soils: 9 percent of the map unit

Bocox soils: 1 percent of the map unit

Es—Tillman and Vernon soils, 2 to 8 percent slopes,

severely eroded

Map Unit Setting

Major land resource area: 78C

Elevation: 1,000 to 2,500 feet

Mean annual precipitation: 20 to 30 inches

Mean annual air temperature: 57 to 66 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Tillman

Extent: 45 percent of the map unit

Geomorphic setting: Paleoterraces on pediments on uplands

Position on the landform: Risers

Parent material: Calcareous, clayey and loamy alluvium derived from claystone

Slope: 2 to 5 percent

Surface runoff class: High
Supplement to the Soil Survey of Comanche County, Oklahoma

17

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Slow

Slowest permeability class within a depth of 80 inches: Slow

Drainage class: Well drained

Available water capacity: About 7.0 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R078CY842OK, Eroded Hardland PE 32-44

Typical profile:

A—0 to 2 inches; clay loam

BA—2 to 13 inches; clay loam

Bt—13 to 24 inches; silty clay

Btk—24 to 40 inches; silty clay

BCk—40 to 50 inches; silty clay

C—50 to 80 inches; clay

Vernon

Extent: 35 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Calcareous, clayey residuum weathered from claystone

Slope: 3 to 8 percent

Surface runoff class: Very high

Soil depth: 17 to 40 inches to bedrock (densic)

Depth to paralithic bedrock: 40 to 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 2.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R078CY865OK, Eroded Clay Prairie PE 32-44

Typical profile:

A—0 to 3 inches; clay

Bk—3 to 17 inches; clay

Cd—17 to 50 inches; clay

Cr—50 to 80 inches; bedrock

Additional Components

Knoco soils: 8 percent of the map unit

Rock outcrop: 7 percent of the map unit

Foard soils: 5 percent of the map unit

Et—Zaneis and Stephenville soils, 2 to 8 percent slopes,

severely eroded

Map Unit Setting

Major land resource area: 80A
Supplement to the Soil Survey of Comanche County, Oklahoma

18

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Zaneis

Extent: 48 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy residuum weathered from sandstone and shale

Slope: 2 to 8 percent

Surface runoff class: High

Soil depth: 40 to 60 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 7.1 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R080AY856OK, Eroded Loamy Prairie PE 44-64

Typical profile:

A—0 to 4 inches; loam

BA—4 to 10 inches; clay loam

Bt—10 to 37 inches; sandy clay loam

BC—37 to 44 inches; fine sandy loam

Cr—44 to 60 inches; bedrock

Stephenville

Extent: 40 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy residuum weathered from sandstone

Slope: 3 to 8 percent

Surface runoff class: Medium

Soil depth: 20 to 40 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 5.6 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R084AY876OK, Eroded Sandy Savannah PE

48-64

Typical profile:

A—0 to 10 inches; fine sandy loam

Bt—10 to 35 inches; sandy clay loam

Cr—35 to 40 inches; bedrock
Supplement to the Soil Survey of Comanche County, Oklahoma

19

Additional Components

Grainola soils: 8 percent of the map unit

Lucien soils: 4 percent of the map unit

EuD—Eufaula fine sand, 5 to 12 percent slopes

Map Unit Setting

Major land resource area: 84A

Elevation: 500 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 190 to 230 days

Major Component Description

Eufaula

Extent: 75 percent of the map unit

Geomorphic setting: Dunes in dune fields on terraces in valleys

Parent material: Eolian sands

Slope: 5 to 12 percent

Surface runoff class: Very low

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Rapid

Slowest permeability class within a depth of 80 inches: Rapid

Drainage class: Somewhat excessively drained

Available water capacity: About 5.4 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R084AY018OK, Deep Sand Savannah PE 48-64

Typical profile:

A—0 to 5 inches; fine sand

E—5 to 40 inches; fine sand

E and Bt—40 to 80 inches; fine sand

Additional Components

Derby soils: 10 percent of the map unit

Konawa soils: 10 percent of the map unit

Dougherty soils: 4 percent of the map unit

Bocox soils: 1 percent of the map unit

FaA—Foard silt loam, 0 to 1 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 800 to 2,650 feet

Mean annual precipitation: 18 to 38 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Foard

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on pediments on uplands
Supplement to the Soil Survey of Comanche County, Oklahoma

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Position on the landform: Treads

Parent material: Granitic, clayey alluvium over shale and siltstone

Slope: 0 to 1 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Moderately well drained

Available water capacity: About 8.3 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Sodic within a depth of 30 inches

Land capability classification, nonirrigated: 4s

Land capability classification, irrigated: 2s

Ecological site number and name: R078CY042OK, Hardland (South) PE 32-44

Typical profile:

A—0 to 9 inches; silt loam

Bt—9 to 22 inches; clay

Btk—22 to 48 inches; clay

BCk—48 to 56 inches; clay

C—56 to 80 inches; clay

Additional Components

Hinkle soils: 5 percent of the map unit

Hollister soils: 5 percent of the map unit

Waurika soils: 5 percent of the map unit

Tillman soils: 4 percent of the map unit

Roscoe soils: 1 percent of the map unit

FsA—Foard-Hinkle complex, 0 to 1 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 800 to 2,650 feet

Mean annual precipitation: 18 to 38 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Foard

Extent: 65 percent of the map unit

Geomorphic setting: Paleoterraces on pediments on uplands

Position on the landform: Treads

Parent material: Granitic, clayey alluvium over shale and siltstone

Slope: 0 to 1 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Moderately well drained

Available water capacity: About 8.3 inches
Supplement to the Soil Survey of Comanche County, Oklahoma

21

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Sodic within a depth of 30 inches

Land capability classification, nonirrigated: 4s

Land capability classification, irrigated: 2s

Ecological site number and name: R078CY042OK, Hardland (South) PE 32-44

Typical profile:

A—0 to 9 inches; silt loam

Bt—9 to 22 inches; clay

Btk—22 to 48 inches; clay

BCk—48 to 56 inches; clay

C—56 to 80 inches; clay

Hinkle

Extent: 25 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Treads

Parent material: Saline, clayey alluvium and/or residuum weathered from granite

Slope: 0 to 1 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 5.8 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Sodic within a depth of 30 inches

Land capability classification, nonirrigated: 4s

Ecological site number and name: R078CY091OK, Slickspot PE 32-44

Typical profile:

An—0 to 6 inches; silt loam

Btn—6 to 16 inches; silty clay

Btnss—16 to 33 inches; silty clay

Btknss—33 to 60 inches; silty clay

C—60 to 80 inches; silty clay

Additional Components

Hollister soils: 4 percent of the map unit

Tillman soils: 2 percent of the map unit

Waurika soils: 2 percent of the map unit

Indiahoma soils: 1 percent of the map unit

Roscoe soils: 1 percent of the map unit

FsB—Foard-Hinkle complex, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 900 to 2,250 feet

Mean annual precipitation: 22 to 30 inches
Supplement to the Soil Survey of Comanche County, Oklahoma

22

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 230 days

Major Component Description

Foard

Extent: 70 percent of the map unit

Geomorphic setting: Paleoterraces on pediments on uplands

Position on the landform: Treads

Parent material: Granitic, clayey alluvium over shale and siltstone

Slope: 1 to 3 percent

Surface runoff class: Very high

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Moderately well drained

Available water capacity: About 8.3 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Sodic within a depth of 30 inches

Land capability classification, nonirrigated: 4s

Land capability classification, irrigated: 3e

Ecological site number and name: R078CY042OK, Hardland (South) PE 32-44

Typical profile:

A—0 to 9 inches; silt loam

Bt—9 to 22 inches; clay

Btk—22 to 48 inches; clay

BCk—48 to 56 inches; clay

C—56 to 80 inches; clay

Hinkle

Extent: 25 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Treads

Parent material: Saline, clayey alluvium and/or residuum weathered from granite

Slope: 1 to 3 percent

Surface runoff class: Very high

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 5.8 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Sodic within a depth of 30 inches

Land capability classification, nonirrigated: 4s

Ecological site number and name: R078CY091OK, Slickspot PE 32-44

Typical profile:

An—0 to 6 inches; silt loam

Btn—6 to 16 inches; silty clay

Btnss—16 to 33 inches; silty clay

Btknss—33 to 60 inches; silty clay

C—60 to 80 inches; silty clay
Supplement to the Soil Survey of Comanche County, Oklahoma

23

Additional Components

Tillman soils: 5 percent of the map unit

FtB—Foard and Tillman soils, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 900 to 3,000 feet

Mean annual precipitation: 17 to 30 inches

Mean annual air temperature: 37 to 68 degrees F

Frost-free period: 185 to 230 days

Major Component Description

Foard

Extent: 60 percent of the map unit

Geomorphic setting: Paleoterraces on pediments on uplands

Position on the landform: Treads

Parent material: Granitic, clayey alluvium over shale and siltstone

Slope: 1 to 3 percent

Surface runoff class: Very high

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Moderately well drained

Available water capacity: About 8.3 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Sodic within a depth of 30 inches

Land capability classification, nonirrigated: 4s

Land capability classification, irrigated: 3e

Ecological site number and name: R078CY042OK, Hardland (South) PE 32-44

Typical profile:

A—0 to 9 inches; silt loam

Bt—9 to 22 inches; clay

Btk—22 to 48 inches; clay

BCk—48 to 56 inches; clay

C—56 to 80 inches; clay

Tillman

Extent: 30 percent of the map unit

Geomorphic setting: Paleoterraces on pediments on uplands

Position on the landform: Treads

Parent material: Calcareous, clayey and loamy alluvium derived from claystone

Slope: 1 to 3 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Slow

Slowest permeability class within a depth of 80 inches: Slow

Drainage class: Well drained

Available water capacity: About 7.0 inches
Supplement to the Soil Survey of Comanche County, Oklahoma

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Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 2e

Land capability classification, irrigated: 2e

Ecological site number and name: R078CY042OK, Hardland (South) PE 32-44

Typical profile:

A—0 to 6 inches; silty clay loam

BA—6 to 13 inches; clay loam

Bt—13 to 24 inches; silty clay

Btk—24 to 40 inches; silty clay

BCk—40 to 50 inches; silty clay

C—50 to 80 inches; clay

Additional Components

Vernon soils: 4 percent of the map unit

Hinkle soils: 3 percent of the map unit

Stamford soils: 3 percent of the map unit

Gc—Brico-Rock outcrop complex, 5 to 40 percent slopes

Map Unit Setting

Major land resource area: 82B

Elevation: 500 to 2,200 feet

Mean annual precipitation: 22 to 48 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 190 to 240 days

Major Component Description

Brico

Extent: 50 percent of the map unit

Geomorphic setting: Mountain slopes on mountains

Position on the landform: Mountainflanks

Parent material: Clayey colluvium derived from granite

Slope: 5 to 20 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 5.5 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R082BY004OK, Boulder Ridge Savannah PE

38-48

Typical profile:

A—0 to 11 inches; very cobbly loam

Bt—11 to 40 inches; very cobbly clay loam

BC—40 to 80 inches; extremely cobbly clay loam
Supplement to the Soil Survey of Comanche County, Oklahoma

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Rock outcrop

Extent: 45 percent of the map unit

Geomorphic setting: Mountain slopes on mountains

Position on the landform: Mountainflanks

Parent material: Granite

Slope: 5 to 40 percent

Surface runoff class: Very high

Land capability classification, nonirrigated: 8s

Additional Components

Lawton soils: 5 percent of the map unit

Go—Granite outcrop

Map Unit Setting

Major land resource area: 82B

Elevation: 500 to 2,200 feet

Mean annual precipitation: 22 to 48 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 190 to 240 days

Major Component Description

Granite outcrop

Extent: 90 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Slope: 20 to 90 percent

Surface runoff class: Very high

Land capability classification, nonirrigated: 8

Additional Components

Brico soils: 10 percent of the map unit

HoB—Hollister silt loam, 0 to 1 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 1,000 to 2,100 feet

Mean annual precipitation: 24 to 30 inches

Mean annual air temperature: 59 to 64 degrees F

Frost-free period: 190 to 230 days

Major Component Description

Hollister

Extent: 100 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Treads

Parent material: Calcareous, clayey alluvium

Slope: 0 to 1 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Slow

Slowest permeability class within a depth of 80 inches: Slow
Supplement to the Soil Survey of Comanche County, Oklahoma

26

Drainage class: Well drained

Available water capacity: About 9.3 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 2s

Land capability classification, irrigated: 1

Ecological site number and name: R078CY042OK, Hardland (South) PE 32-44

Typical profile:

A—0 to 8 inches; silt loam

BA—8 to 16 inches; silty clay loam

Bt—16 to 30 inches; silty clay

C—30 to 80 inches; silty clay loam

KnB3—Konawa loamy fine sand, 3 to 8 percent slopes,

severely eroded

Map Unit Setting

Major land resource area: 84A

Elevation: 500 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 66 degrees F

Frost-free period: 190 to 240 days

Major Component Description

Konawa

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Risers

Parent material: Loamy and sandy alluvium

Slope: 3 to 8 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 8.5 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R084AY818OK, Eroded Deep Sand Savannah PE

48-64

Typical profile:

A—0 to 6 inches; loamy fine sand

Bt—6 to 41 inches; sandy clay loam

C—41 to 80 inches; fine sandy loam

Additional Components

Eufaula soils: 7 percent of the map unit

Stephenville soils: 7 percent of the map unit

Windthorst soils: 6 percent of the map unit
Supplement to the Soil Survey of Comanche County, Oklahoma

27

KoB—Konawa loamy fine sand, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 84A

Elevation: 500 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 190 to 230 days

Major Component Description

Konawa

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Treads

Parent material: Loamy and sandy alluvium

Slope: 1 to 3 percent

Surface runoff class: Low

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 8.0 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R084AY018OK, Deep Sand Savannah PE

48-64

Typical profile:

A—0 to 8 inches; loamy fine sand

E—8 to 17 inches; loamy fine sand

Bt—17 to 41 inches; sandy clay loam

C—41 to 80 inches; fine sandy loam

Additional Components

Dougherty soils: 5 percent of the map unit

Newalla soils: 5 percent of the map unit

Stephenville soils: 5 percent of the map unit

Eufaula soils: 4 percent of the map unit

Bocox soils: 1 percent of the map unit

KoC—Konawa loamy fine sand, 3 to 5 percent slopes

Map Unit Setting

Major land resource area: 84A

Elevation: 500 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Konawa

Extent: 80 percent of the map unit
Supplement to the Soil Survey of Comanche County, Oklahoma

28

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Risers

Parent material: Loamy and sandy alluvium

Slope: 3 to 5 percent

Surface runoff class: Low

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 8.0 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R084AY018OK, Deep Sand Savannah PE

48-64

Typical profile:

A—0 to 8 inches; loamy fine sand

E—8 to 17 inches; loamy fine sand

Bt—17 to 41 inches; sandy clay loam

C—41 to 80 inches; fine sandy loam

Additional Components

Dougherty soils: 5 percent of the map unit

Newalla soils: 5 percent of the map unit

Stephenville soils: 5 percent of the map unit

Eufaula soils: 4 percent of the map unit

Bocox soils: 1 percent of the map unit

KoC2—Konawa loamy fine sand, 3 to 5 percent slopes,

eroded

Map Unit Setting

Major land resource area: 84A

Elevation: 500 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 190 to 230 days

Major Component Description

Konawa

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Risers

Parent material: Loamy and sandy alluvium

Slope: 3 to 5 percent

Surface runoff class: Low

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 8.5 inches
Supplement to the Soil Survey of Comanche County, Oklahoma

29

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 4e

Ecological site number and name: R084AY818OK, Eroded Deep Sand Savannah PE

48-64

Typical profile:

A—0 to 6 inches; loamy fine sand

Bt—6 to 41 inches; sandy clay loam

C—41 to 80 inches; fine sandy loam

Additional Components

Stephenville soils: 6 percent of the map unit

Dougherty soils: 5 percent of the map unit

Eufaula soils: 4 percent of the map unit

Newalla soils: 4 percent of the map unit

Bocox soils: 1 percent of the map unit

LaB—Lawton loam, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 82B

Elevation: 1,000 to 2,650 feet

Mean annual precipitation: 18 to 32 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Lawton

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Treads

Parent material: Granitic outwash and loamy alluvium

Slope: 1 to 3 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 10.1 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 2e

Ecological site number and name: R082BY056OK, Loamy Prairie PE 38-48

Typical profile:

A—0 to 11 inches; loam

BA—11 to 18 inches; clay loam

Bt—18 to 47 inches; clay loam

BC—47 to 80 inches; sandy clay loam

Additional Components

Foard soils: 5 percent of the map unit
Supplement to the Soil Survey of Comanche County, Oklahoma

30

Hollister soils: 5 percent of the map unit

Tillman soils: 5 percent of the map unit

Indiahoma soils: 4 percent of the map unit

Roscoe soils: 1 percent of the map unit

LaC—Lawton loam, 3 to 5 percent slopes

Map Unit Setting

Major land resource area: 82B

Elevation: 1,000 to 2,500 feet

Mean annual precipitation: 20 to 32 inches

Mean annual air temperature: 57 to 66 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Lawton

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Risers

Parent material: Granitic outwash and loamy alluvium

Slope: 3 to 5 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 10.1 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R082BY056OK, Loamy Prairie PE 38-48

Typical profile:

A—0 to 11 inches; loam

BA—11 to 18 inches; clay loam

Bt—18 to 47 inches; clay loam

BC—47 to 80 inches; sandy clay loam

Additional Components

Foard soils: 7 percent of the map unit

Tillman soils: 7 percent of the map unit

Vernon soils: 6 percent of the map unit

LaC2—Lawton loam, 3 to 5 percent slopes, eroded

Map Unit Setting

Major land resource area: 82B

Elevation: 1,000 to 2,500 feet

Mean annual precipitation: 20 to 32 inches

Mean annual air temperature: 57 to 66 degrees F

Frost-free period: 185 to 240 days
Supplement to the Soil Survey of Comanche County, Oklahoma

31

Major Component Description

Lawton

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Risers

Parent material: Granitic outwash and loamy alluvium

Slope: 3 to 5 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 9.8 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R082BY856OK, Eroded Loamy Prairie PE

38-48

Typical profile:

A—0 to 5 inches; loam

BA—5 to 12 inches; clay loam

Bt—12 to 41 inches; clay loam

BC—41 to 80 inches; sandy clay loam

Additional Components

Foard soils: 7 percent of the map unit

Tillman soils: 7 percent of the map unit

Vernon soils: 6 percent of the map unit

Lc—Lela clay, 0 to 1 percent slopes, occasionally flooded

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 230 days

Major Component Description

Lela

Extent: 75 percent of the map unit

Geomorphic setting: Flood plains in river valleys

Parent material: Clayey alluvium

Slope: 0 to 1 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Somewhat poorly drained

Available water capacity: About 7.4 inches

Depth to the top of the seasonal high water table: Greater than 6 feet
Supplement to the Soil Survey of Comanche County, Oklahoma

32

Flooding: Occasional

Ponding: None

Land capability classification, nonirrigated: 4w

Ecological site number and name: R080AY045OK, Heavy Bottomland PE 44-64

Typical profile:

A—0 to 16 inches; clay

C—16 to 80 inches; clay

Additional Components

Miller soils: 10 percent of the map unit

Ashport soils: 5 percent of the map unit

Port soils: 5 percent of the map unit

Mclain soils: 4 percent of the map unit

Lebron soils: 1 percent of the map unit

LfC—Lawton-Foard complex, 3 to 5 percent slopes

Map Unit Setting

Major land resource area: 82B

Elevation: 900 to 2,250 feet

Mean annual precipitation: 22 to 32 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 230 days

Major Component Description

Lawton

Extent: 60 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Risers

Parent material: Granitic outwash and loamy alluvium

Slope: 3 to 5 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 10.1 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R082BY056OK, Loamy Prairie PE 38-48

Typical profile:

A—0 to 11 inches; loam

BA—11 to 18 inches; clay loam

Bt—18 to 47 inches; clay loam

BC—47 to 80 inches; sandy clay loam

Foard

Extent: 30 percent of the map unit

Geomorphic setting: Paleoterraces on pediments on uplands

Position on the landform: Risers

Parent material: Granitic, clayey alluvium over shale and siltstone
Supplement to the Soil Survey of Comanche County, Oklahoma

33

Slope: 3 to 5 percent

Surface runoff class: Very high

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Moderately well drained

Available water capacity: About 8.3 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Sodic within a depth of 30 inches

Land capability classification, nonirrigated: 4s

Land capability classification, irrigated: 3e

Ecological site number and name: R078CY042OK, Hardland (South) PE 32-44

Typical profile:

A—0 to 9 inches; silt loam

Bt—9 to 22 inches; clay

Btk—22 to 48 inches; clay

BCk—48 to 56 inches; clay

C—56 to 80 inches; clay

Additional Components

Tillman soils: 4 percent of the map unit

Hinkle soils: 3 percent of the map unit

Rock outcrop: 3 percent of the map unit

Lm—Somervell very cobbly loam, 8 to 45 percent slopes

Map Unit Setting

Major land resource area: 82B

Elevation: 500 to 2,300 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 60 to 68 degrees F

Frost-free period: 200 to 240 days

Major Component Description

Somervell

Extent: 85 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy, gravelly residuum weathered from limestone

Slope: 8 to 45 percent

Surface runoff class: High

Soil depth: 20 to 40 inches to bedrock (lithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Slow

Drainage class: Well drained

Available water capacity: About 1.8 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 7e
Supplement to the Soil Survey of Comanche County, Oklahoma

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Ecological site number and name: R082BY048OK, Limestone Ridge PE 38-48

Typical profile:

A—0 to 10 inches; very cobbly loam

Bk—10 to 20 inches; very cobbly clay loam

R—20 to 30 inches; bedrock

Additional Components

Kiti soils: 8 percent of the map unit

Rock outcrop: 7 percent of the map unit

LzD—Lucien-Grainola-Zaneis complex, 5 to 12 percent

slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 190 to 230 days

Major Component Description

Lucien

Extent: 35 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy residuum weathered from sandstone and shale

Slope: 5 to 12 percent

Surface runoff class: Very high

Soil depth: 10 to 20 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately rapid

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 1.8 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R080AY083OK, Shallow Prairie PE 44-64

Typical profile:

A—0 to 10 inches; loam

Cr—10 to 15 inches; bedrock

Grainola

Extent: 30 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Calcareous, clayey residuum weathered from shale

Slope: 5 to 12 percent

Surface runoff class: Very high

Soil depth: 20 to 40 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Slow

Slowest permeability class within a depth of 80 inches: Impermeable
Supplement to the Soil Survey of Comanche County, Oklahoma

35

Drainage class: Well drained

Available water capacity: About 5.7 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R080AY011OK, Claypan Prairie (South) PE 44-64

Typical profile:

A—0 to 4 inches; clay loam

BA—4 to 17 inches; stony clay loam

Btk—17 to 36 inches; silty clay

Cr—36 to 50 inches; bedrock

Zaneis

Extent: 20 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy residuum weathered from sandstone and shale

Slope: 5 to 8 percent

Surface runoff class: High

Soil depth: 40 to 60 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Impermeable

Drainage class: Well drained

Available water capacity: About 8.1 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 4e

Ecological site number and name: R080AY056OK, Loamy Prairie PE 44-64

Typical profile:

A—0 to 6 inches; loam

BA—6 to 12 inches; clay loam

Bt—12 to 50 inches; clay loam

Cr—50 to 61 inches; bedrock

Additional Components

Minco soils: 5 percent of the map unit

Rock outcrop: 5 percent of the map unit

Yahola soils: 5 percent of the map unit

M-W—Miscellaneous water

Map Unit Setting

Major land resource area: 78C

Elevation: 250 to 4,000 feet

Mean annual precipitation: 26 to 30 inches

Mean annual air temperature: 59 to 63 degrees F

Frost-free period: 200 to 220 days

Major Component Description

Water

Extent: 100 percent of the map unit
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36

Definition: This map unit consists of areas of waste water. Examples include sewage

lagoons and impoundments for industrial waste water.

Geomorphic setting: Sewage lagoons

Land capability classification, nonirrigated: 8

Mc—Miller clay, 0 to 1 percent slopes, occasionally

flooded

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 230 days

Major Component Description

Miller

Extent: 80 percent of the map unit

Geomorphic setting: Flood plains in river valleys

Parent material: Calcareous, clayey alluvium

Slope: 0 to 1 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Moderately well drained

Available water capacity: About 9.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: Occasional

Ponding: None

Land capability classification, nonirrigated: 4w

Ecological site number and name: R080AY045OK, Heavy Bottomland PE 44-64

Typical profile:

A—0 to 22 inches; clay

AC—22 to 38 inches; clay

C—38 to 80 inches; clay

Additional Components

Ashport soils: 5 percent of the map unit

Lela soils: 5 percent of the map unit

Port soils: 5 percent of the map unit

Mclain soils: 4 percent of the map unit

Hibsaw soils: 1 percent of the map unit

MnC—Minco loam, 3 to 8 percent slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches
Supplement to the Soil Survey of Comanche County, Oklahoma

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Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Minco

Extent: 85 percent of the map unit

Geomorphic setting: Stream terraces in river valleys

Position on the landform: Risers

Parent material: Loamy alluvium and/or eolian deposits

Slope: 3 to 8 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 11.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 4e

Ecological site number and name: R080AY056OK, Loamy Prairie PE 44-64

Typical profile:

A—0 to 18 inches; loam

Bw—18 to 80 inches; loam

Additional Components

Lucien soils: 8 percent of the map unit

Zaneis soils: 7 percent of the map unit

NorB—Norge silt loam, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 190 to 230 days

Major Component Description

Norge

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Treads

Parent material: Loamy alluvium

Slope: 1 to 3 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 11.3 inches

Depth to the top of the seasonal high water table: Greater than 6 feet
Supplement to the Soil Survey of Comanche County, Oklahoma

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Flooding: None

Ponding: None

Land capability classification, nonirrigated: 2e

Ecological site number and name: R080AY056OK, Loamy Prairie PE 44-64

Typical profile:

A—0 to 8 inches; silt loam

BA—8 to 12 inches; silty clay loam

Bt—12 to 46 inches; silty clay loam

BC—46 to 80 inches; silty clay loam

Additional Components

Grant soils: 9 percent of the map unit

Pond Creek soils: 5 percent of the map unit

Renfrow soils: 5 percent of the map unit

Waurika soils: 1 percent of the map unit

NorC—Norge silt loam, 3 to 5 percent slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 190 to 230 days

Major Component Description

Norge

Extent: 85 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Risers

Parent material: Loamy alluvium

Slope: 3 to 5 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 11.3 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R080AY056OK, Loamy Prairie PE 44-64

Typical profile:

A—0 to 8 inches; silt loam

BA—8 to 12 inches; silty clay loam

Bt—12 to 46 inches; silty clay loam

BC—46 to 80 inches; silty clay loam

Additional Components

Grant soils: 10 percent of the map unit

Huska soils: 5 percent of the map unit
Supplement to the Soil Survey of Comanche County, Oklahoma

39

NOTCOM—Area not surveyed, access denied

Map Unit Setting

Major land resource area: 82B

Pc—Ashport clay loam, 0 to 1 percent slopes,

occasionally flooded

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 2,250 feet

Mean annual precipitation: 20 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Ashport

Extent: 75 percent of the map unit

Geomorphic setting: Flood plains in river valleys

Parent material: Fine-silty alluvium

Slope: 0 to 1 percent

Surface runoff class: Negligible

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 11.5 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: Occasional

Ponding: None

Land capability classification, nonirrigated: 2w

Ecological site number and name: R080AY050OK, Loamy Bottomland PE 44-64

Typical profile:

A—0 to 15 inches; clay loam

C—15 to 80 inches; loam

Additional Components

Clairemont soils: 5 percent of the map unit

Miller soils: 5 percent of the map unit

Port soils: 5 percent of the map unit

Wheatwood soils: 5 percent of the map unit

Lela soils: 4 percent of the map unit

Retrop soils: 1 percent of the map unit

PIT—Pits

Map Unit Setting

Major land resource area: 78C

Elevation: 500 to 2,200 feet
Supplement to the Soil Survey of Comanche County, Oklahoma

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Mean annual precipitation: 26 to 30 inches

Mean annual air temperature: 59 to 63 degrees F

Frost-free period: 200 to 220 days

Major Component Description

Pits

Extent: 100 percent of the map unit

Geomorphic setting: Borrow pits

Parent material: Mine spoil or earthy fill

Slope: 0 to 4 percent

Surface runoff class: High

Land capability classification, nonirrigated: 8

Po—Ashport loam, 0 to 1 percent slopes, occasionally

flooded

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 2,000 feet

Mean annual precipitation: 22 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Ashport

Extent: 80 percent of the map unit

Geomorphic setting: Flood plains in river valleys

Parent material: Fine-silty alluvium

Slope: 0 to 1 percent

Surface runoff class: Negligible

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 11.8 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: Occasional

Ponding: None

Land capability classification, nonirrigated: 2w

Ecological site number and name: R080AY050OK, Loamy Bottomland PE 44-64

Typical profile:

A—0 to 18 inches; loam

C—18 to 80 inches; loam

Additional Components

Easpur soils: 9 percent of the map unit

Port soils: 5 percent of the map unit

Wheatwood soils: 5 percent of the map unit

Retrop soils: 1 percent of the map unit
Supplement to the Soil Survey of Comanche County, Oklahoma

41

Ps—Ashport-Oscar complex, 0 to 1 percent slopes,

occasionally flooded

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 2,250 feet

Mean annual precipitation: 20 to 40 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Ashport

Extent: 69 percent of the map unit

Geomorphic setting: Flood plains in river valleys

Parent material: Fine-silty alluvium

Slope: 0 to 1 percent

Surface runoff class: Negligible

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 11.5 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: Occasional

Ponding: None

Land capability classification, nonirrigated: 2w

Ecological site number and name: R080AY050OK, Loamy Bottomland PE 44-64

Typical profile:

A—0 to 15 inches; clay loam

C—15 to 80 inches; loam

Oscar

Extent: 20 percent of the map unit

Geomorphic setting: Flood plains in river valleys

Parent material: Saline, loamy alluvium

Slope: 0 to 1 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Slow

Slowest permeability class within a depth of 80 inches: Slow

Drainage class: Moderately well drained

Available water capacity: About 7.9 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: Occasional

Ponding: None

Other properties: Saline within a depth of 30 inches; sodic within a depth of 30 inches

Land capability classification, nonirrigated: 6s

Ecological site number and name: R080AY001OK, Alkali Bottomland PE 44-64

Typical profile:

A—0 to 5 inches; loam

Btn—5 to 20 inches; silty clay loam

C—20 to 80 inches; silty clay loam
Supplement to the Soil Survey of Comanche County, Oklahoma

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Additional Components

Clairemont soils: 2 percent of the map unit

Lela soils: 2 percent of the map unit

Miller soils: 2 percent of the map unit

Port soils: 2 percent of the map unit

Wheatwood soils: 2 percent of the map unit

Retrop soils: 1 percent of the map unit

QUA—Quarry

Map Unit Setting

Major land resource area: 78C

Elevation: 500 to 2,500 feet

Mean annual precipitation: 26 to 30 inches

Mean annual air temperature: 59 to 63 degrees F

Frost-free period: 200 to 220 days

Major Component Description

Quarries

Extent: 100 percent of the map unit

Geomorphic setting: Surface mines

Parent material: Mine spoil or earthy fill

Slope: 0 to 99 percent

Surface runoff class: Very high

Land capability classification, nonirrigated: 8

Ro—Rock outcrop-Brico complex, 3 to 20 percent slopes

Map Unit Setting

Major land resource area: 82B

Elevation: 500 to 2,200 feet

Mean annual precipitation: 22 to 48 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Rock outcrop

Extent: 70 percent of the map unit

Geomorphic setting: Mountain slopes on mountains

Position on the landform: Mountainflanks

Parent material: Granite

Slope: 3 to 20 percent

Surface runoff class: Very high

Land capability classification, nonirrigated: 8s

Brico

Extent: 20 percent of the map unit

Geomorphic setting: Mountain slopes on mountains

Position on the landform: Mountainflanks

Parent material: Clayey colluvium derived from granite

Slope: 3 to 20 percent

Surface runoff class: High

Soil depth: Greater than 60 inches
Supplement to the Soil Survey of Comanche County, Oklahoma

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Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 6.1 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R082BY004OK, Boulder Ridge Savannah PE 38-48

Typical profile:

A—0 to 11 inches; cobbly loam

Bt—11 to 40 inches; very cobbly clay loam

BC—40 to 80 inches; very cobbly clay loam

Additional Components

Foard soils: 5 percent of the map unit

Lawton soils: 5 percent of the map unit

Sc—Hinkle loam, 0 to 3 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 900 to 2,250 feet

Mean annual precipitation: 22 to 32 inches

Mean annual air temperature: 57 to 65 degrees F

Frost-free period: 185 to 230 days

Major Component Description

Hinkle

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on uplands

Position on the landform: Treads

Parent material: Saline, clayey alluvium and/or residuum weathered from granite

Slope: 0 to 3 percent

Surface runoff class: Very high

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 5.8 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Sodic within a depth of 30 inches

Land capability classification, nonirrigated: 4s

Ecological site number and name: R078CY091OK, Slickspot PE 32-44

Typical profile:

An—0 to 6 inches; loam

Btn—6 to 16 inches; silty clay

Btnss—16 to 33 inches; silty clay

Btknss—33 to 60 inches; silty clay

C—60 to 80 inches; silty clay
Supplement to the Soil Survey of Comanche County, Oklahoma

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Additional Components

Foard soils: 7 percent of the map unit

Lawton soils: 7 percent of the map unit

Tillman soils: 6 percent of the map unit

SmA—Stamford clay, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 1,000 to 3,000 feet

Mean annual precipitation: 17 to 30 inches

Mean annual air temperature: 37 to 68 degrees F

Frost-free period: 190 to 230 days

Major Component Description

Stamford

Extent: 85 percent of the map unit

Geomorphic setting: Flats on uplands

Position on the landform: Treads

Parent material: Calcareous, clayey residuum weathered from claystone

Slope: 1 to 3 percent

Surface runoff class: Very high

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 9.0 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R078CY042OK, Hardland (South) PE 32-44

Typical profile:

A—0 to 14 inches; clay

AC—14 to 50 inches; clay

C—50 to 80 inches; clay

Additional Components

Vernon soils: 8 percent of the map unit

Knoco soils: 7 percent of the map unit

St—Brico soils and Rock outcrop, 15 to 50 percent slopes

Map Unit Setting

Major land resource area: 82B

Elevation: 500 to 2,200 feet

Mean annual precipitation: 22 to 48 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Brico

Extent: 50 percent of the map unit
Supplement to the Soil Survey of Comanche County, Oklahoma

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Geomorphic setting: Mountain slopes on mountains

Position on the landform: Mountainflanks

Parent material: Clayey colluvium derived from granite

Slope: 15 to 20 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Well drained

Available water capacity: About 5.5 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 6e

Ecological site number and name: R082BY004OK, Boulder Ridge Savannah PE

38-48

Typical profile:

A—0 to 11 inches; very cobbly loam

Bt—11 to 40 inches; very cobbly clay loam

BC—40 to 80 inches; very cobbly clay loam

Rock outcrop

Extent: 40 percent of the map unit

Geomorphic setting: Mountain slopes on mountains

Position on the landform: Mountainflanks

Parent material: Granite

Slope: 15 to 50 percent

Surface runoff class: Very high

Land capability classification, nonirrigated: 8s

Additional Components

Foard soils: 5 percent of the map unit

Lawton soils: 5 percent of the map unit

Ta—Kiti-Rock outcrop complex, 3 to 25 percent slopes

Map Unit Setting

Major land resource area: 82B

Elevation: 500 to 2,300 feet

Mean annual precipitation: 22 to 48 inches

Mean annual air temperature: 57 to 68 degrees F

Frost-free period: 190 to 240 days

Major Component Description

Kiti

Extent: 55 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy residuum weathered from limestone

Slope: 3 to 25 percent

Surface runoff class: Very high

Soil depth: 4 to 20 inches to bedrock (lithic)
Supplement to the Soil Survey of Comanche County, Oklahoma

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Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 0.8 inch

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 7e

Ecological site number and name: R085XY026OK, Edgerock PE 56-66

Typical profile:

A—0 to 7 inches; flaggy silt loam

R—7 to 10 inches; bedrock

Rock outcrop

Extent: 35 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Limestone

Slope: 3 to 25 percent

Surface runoff class: Very high

Land capability classification, nonirrigated: 8s

Additional Components

Somervell soils: 10 percent of the map unit

TmC—Tillman clay loam, 3 to 5 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 1,000 to 2,500 feet

Mean annual precipitation: 20 to 32 inches

Mean annual air temperature: 57 to 66 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Tillman

Extent: 80 percent of the map unit

Geomorphic setting: Paleoterraces on pediments on uplands

Position on the landform: Risers

Parent material: Calcareous, clayey and loamy alluvium derived from claystone

Slope: 3 to 5 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Slow

Slowest permeability class within a depth of 80 inches: Slow

Drainage class: Well drained

Available water capacity: About 7.0 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e
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Ecological site number and name: R078CY042OK, Hardland (South) PE 32-44

Typical profile:

A—0 to 6 inches; clay loam

BA—6 to 13 inches; clay loam

Bt—13 to 24 inches; silty clay

Btk—24 to 40 inches; silty clay

BCk—40 to 50 inches; silty clay

C—50 to 80 inches; clay

Additional Components

Foard soils: 7 percent of the map unit

Lawton soils: 7 percent of the map unit

Vernon soils: 6 percent of the map unit

VaA—Vanoss loam, 0 to 1 percent slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Vanoss

Extent: 85 percent of the map unit

Geomorphic setting: Paleoterraces in valleys

Position on the landform: Treads

Parent material: Loamy alluvium

Slope: 0 to 1 percent

Surface runoff class: Negligible

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 11.0 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 1

Ecological site number and name: R080AY056OK, Loamy Prairie PE 44-64

Typical profile:

A—0 to 12 inches; loam

BA—12 to 18 inches; loam

Bt—18 to 36 inches; clay loam

BC—36 to 48 inches; sandy clay loam

C—48 to 82 inches; fine sandy loam

Additional Components

Zaneis soils: 8 percent of the map unit

Stephenville soils: 7 percent of the map unit
Supplement to the Soil Survey of Comanche County, Oklahoma

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VaB—Vanoss loam, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Vanoss

Extent: 85 percent of the map unit

Geomorphic setting: Paleoterraces in valleys

Position on the landform: Treads

Parent material: Loamy alluvium

Slope: 1 to 3 percent

Surface runoff class: Low

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 11.0 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 2e

Ecological site number and name: R080AY056OK, Loamy Prairie PE 44-64

Typical profile:

A—0 to 12 inches; loam

BA—12 to 18 inches; loam

Bt—18 to 36 inches; clay loam

BC—36 to 48 inches; sandy clay loam

C—48 to 82 inches; fine sandy loam

Additional Components

Zaneis soils: 8 percent of the map unit

Stephenville soils: 7 percent of the map unit

VeC—Vernon clay, 3 to 5 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 1,000 to 3,000 feet

Mean annual precipitation: 17 to 30 inches

Mean annual air temperature: 37 to 68 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Vernon

Extent: 80 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes
Supplement to the Soil Survey of Comanche County, Oklahoma

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Parent material: Calcareous, clayey residuum weathered from claystone

Slope: 3 to 5 percent

Surface runoff class: Very high

Soil depth: 17 to 40 inches to bedrock (densic)

Depth to paralithic bedrock: 40 to 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 2.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 4s

Land capability classification, irrigated: 4e

Ecological site number and name: R078CY031OK, Clay Prairie (South) PE 32-44

Typical profile:

A—0 to 4 inches; clay

Bk—4 to 17 inches; clay

Cd—17 to 50 inches; bedrock

Cr—50 to 80 inches; bedrock

Additional Components

Foard soils: 7 percent of the map unit

Stamford soils: 7 percent of the map unit

Tillman soils: 6 percent of the map unit

VeD—Vernon-Knoco complex, 5 to 12 percent slopes

Map Unit Setting

Major land resource area: 78C

Elevation: 1,000 to 3,000 feet

Mean annual precipitation: 17 to 30 inches

Mean annual air temperature: 37 to 68 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Vernon

Extent: 60 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Calcareous, clayey residuum weathered from claystone

Slope: 5 to 12 percent

Surface runoff class: Very high

Soil depth: 17 to 40 inches to bedrock (densic)

Depth to paralithic bedrock: 40 to 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 2.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None
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Land capability classification, nonirrigated: 6e

Ecological site number and name: R078CY031OK, Clay Prairie (South) PE 32-44

Typical profile:

A—0 to 4 inches; clay

Bk—4 to 17 inches; clay

Cd—17 to 50 inches; bedrock

Cr—50 to 80 inches; bedrock

Knoco

Extent: 30 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Calcareous, clayey residuum weathered from shale

Slope: 5 to 12 percent

Surface runoff class: Very high

Soil depth: 4 to 10 inches to bedrock (densic)

Depth to paralithic bedrock: 10 to 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Well drained

Available water capacity: About 1.3 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Sodic within a depth of 30 inches

Land capability classification, nonirrigated: 7s

Ecological site number and name: R078CY066OK, Shallow Clay Prairie PE 32-44

Typical profile:

A—0 to 9 inches; clay

Cd—9 to 19 inches; bedrock

Cr—19 to 60 inches; bedrock

Additional Components

Stamford soils: 4 percent of the map unit

Foard soils: 3 percent of the map unit

Tillman soils: 3 percent of the map unit

W—Water

Map Unit Setting

Major land resource area: 78C

Elevation: 250 to 4,000 feet

Mean annual precipitation: 22 to 48 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 190 to 240 days

Major Component Description

Water

Extent: 100 percent of the map unit

Definition: This map unit consists of areas of fresh water, including ponds, lakes, and

rivers.

Geomorphic setting: Valleys

Land capability classification, nonirrigated: 8
Supplement to the Soil Survey of Comanche County, Oklahoma

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Wa—Waurika silt loam, 0 to 1 percent slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 2,000 feet

Mean annual precipitation: 22 to 38 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 185 to 230 days

Major Component Description

Waurika

Extent: 80 percent of the map unit

Geomorphic setting: Plains on paleoterraces on uplands

Position on the landform: Talf

Parent material: Clayey alluvium and/or residuum weathered from shale

Slope: 0 to 1 percent

Surface runoff class: Very high

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Very slow

Drainage class: Somewhat poorly drained

Available water capacity: About 9.6 inches

Depth to the top of the seasonal high water table: 0.5 to 1.5 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3w

Ecological site number and name: R080AY011OK, Claypan Prairie (South) PE 44-64

Typical profile:

A—0 to 11 inches; silt loam

E—11 to 14 inches; silt loam

Bt—14 to 32 inches; clay

BCk—32 to 45 inches; clay

C—45 to 80 inches; clay loam

Additional Components

Foard soils: 10 percent of the map unit

Hinkle soils: 5 percent of the map unit

Vanoss soils: 5 percent of the map unit

We—Tribbey fine sandy loam, 0 to 1 percent slopes,

frequently flooded

Map Unit Setting

Major land resource area: 84A

Elevation: 700 to 2,200 feet

Mean annual precipitation: 22 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Tribbey

Extent: 80 percent of the map unit
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Geomorphic setting: Flood plains in river valleys

Parent material: Loamy and/or sandy alluvium

Slope: 0 to 1 percent

Surface runoff class: High

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately rapid

Slowest permeability class within a depth of 80 inches: Moderately rapid

Drainage class: Somewhat poorly drained

Available water capacity: About 8.5 inches

Depth to the top of the seasonal high water table: 0.5 to 3.5 feet

Flooding: Frequent

Ponding: None

Land capability classification, nonirrigated: 5w

Ecological site number and name: R084AY095OK, Subirrigated PE 48-64

Typical profile:

A—0 to 10 inches; fine sandy loam

C1—10 to 40 inches; fine sandy loam

C2—40 to 80 inches; stratified loamy fine sand to loam

Additional Components

Gracemont soils: 5 percent of the map unit

Gracemore soils: 5 percent of the map unit

Pulaski soils: 5 percent of the map unit

Ezell soils: 3 percent of the map unit

Yahola soils: 2 percent of the map unit

WhB—Windthorst sandy loam, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 84B

Elevation: 500 to 2,000 feet

Mean annual precipitation: 22 to 40 inches

Mean annual air temperature: 57 to 66 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Windthorst

Extent: 85 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Shoulders

Parent material: Clayey and/or loamy alluvium over residuum weathered from

sedimentary rock

Slope: 1 to 3 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Moderately well drained

Available water capacity: About 8.4 inches

Depth to the top of the seasonal high water table: Greater than 6 feet
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Flooding: None

Ponding: None

Land capability classification, nonirrigated: 2e

Ecological site number and name: R084BY076OK, Sandy Savannah PE 44-64

Typical profile:

A—0 to 8 inches; sandy loam

Bt1—8 to 21 inches; sandy clay

Bt2—21 to 48 inches; sandy clay

2C—48 to 80 inches; clay

Additional Components

Konawa soils: 8 percent of the map unit

Lawton soils: 7 percent of the map unit

WhC—Windthorst sandy loam, 3 to 5 percent slopes

Map Unit Setting

Major land resource area: 84B

Elevation: 500 to 2,000 feet

Mean annual precipitation: 22 to 40 inches

Mean annual air temperature: 57 to 66 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Windthorst

Extent: 85 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Clayey and/or loamy alluvium over residuum weathered from

sedimentary rock

Slope: 3 to 5 percent

Surface runoff class: Medium

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Moderately slow

Drainage class: Moderately well drained

Available water capacity: About 8.4 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R084BY076OK, Sandy Savannah PE 44-64

Typical profile:

A—0 to 8 inches; sandy loam

Bt1—8 to 21 inches; sandy clay

Bt2—21 to 48 inches; sandy clay

2C—48 to 80 inches; clay

Additional Components

Konawa soils: 8 percent of the map unit

Lawton soils: 7 percent of the map unit
Supplement to the Soil Survey of Comanche County, Oklahoma

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ZaB—Zaneis loam, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Zaneis

Extent: 80 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Shoulders

Parent material: Loamy residuum weathered from sandstone and shale

Slope: 1 to 3 percent

Surface runoff class: Medium

Soil depth: 40 to 60 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Impermeable

Drainage class: Well drained

Available water capacity: About 8.1 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 2e

Ecological site number and name: R080AY056OK, Loamy Prairie PE 44-64

Typical profile:

A—0 to 6 inches; loam

BA—6 to 12 inches; clay loam

Bt—12 to 50 inches; clay loam

Cr—50 to 61 inches; bedrock

Additional Components

Grainola soils: 5 percent of the map unit

Lucien soils: 5 percent of the map unit

Stephenville soils: 5 percent of the map unit

Vanoss soils: 5 percent of the map unit

ZaC—Zaneis loam, 3 to 5 percent slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Zaneis

Extent: 80 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes
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Parent material: Loamy residuum weathered from sandstone and shale

Slope: 3 to 5 percent

Surface runoff class: Medium

Soil depth: 40 to 60 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Impermeable

Drainage class: Well drained

Available water capacity: About 8.1 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R080AY056OK, Loamy Prairie PE 44-64

Typical profile:

A—0 to 6 inches; loam

BA—6 to 12 inches; clay loam

Bt—12 to 50 inches; clay loam

Cr—50 to 61 inches; bedrock

Additional Components

Grainola soils: 7 percent of the map unit

Lucien soils: 7 percent of the map unit

Stephenville soils: 6 percent of the map unit

ZaC2—Zaneis loam, 3 to 5 percent slopes, eroded

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 1,500 feet

Mean annual precipitation: 26 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 200 to 230 days

Major Component Description

Zaneis

Extent: 80 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Backslopes

Parent material: Loamy residuum weathered from sandstone and shale

Slope: 3 to 5 percent

Surface runoff class: High

Soil depth: 40 to 60 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Impermeable

Drainage class: Well drained

Available water capacity: About 7.2 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 3e

Ecological site number and name: R080AY856OK, Eroded Loamy Prairie PE 44-64
Supplement to the Soil Survey of Comanche County, Oklahoma

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Typical profile:

A—0 to 6 inches; loam

BA—6 to 12 inches; clay loam

Bt—12 to 44 inches; clay loam

Cr—44 to 61 inches; bedrock

Additional Components

Grainola soils: 7 percent of the map unit

Lucien soils: 7 percent of the map unit

Stephenville soils: 6 percent of the map unit

ZsB—Zaneis-Huska complex, 1 to 3 percent slopes

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 2,000 feet

Mean annual precipitation: 22 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 185 to 230 days

Major Component Description

Zaneis

Extent: 40 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Shoulders

Parent material: Loamy residuum weathered from sandstone and shale

Slope: 1 to 3 percent

Surface runoff class: Medium

Soil depth: 40 to 60 inches to bedrock (paralithic)

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderately slow

Slowest permeability class within a depth of 80 inches: Impermeable

Drainage class: Well drained

Available water capacity: About 8.1 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Land capability classification, nonirrigated: 2e

Ecological site number and name: R080AY056OK, Loamy Prairie PE 44-64

Typical profile:

A—0 to 6 inches; loam

BA—6 to 12 inches; clay loam

Bt—12 to 50 inches; clay loam

Cr—50 to 61 inches; bedrock

Huska

Extent: 30 percent of the map unit

Geomorphic setting: Hillslopes on hills on uplands

Position on hillslope: Shoulders

Parent material: Saline, clayey residuum weathered from sandstone and shale

Slope: 1 to 3 percent

Surface runoff class: Very high

Soil depth: 40 to 60 inches to bedrock (paralithic)
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Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Very slow

Slowest permeability class within a depth of 80 inches: Impermeable

Drainage class: Moderately well drained

Available water capacity: About 4.6 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: None

Ponding: None

Other properties: Saline within a depth of 30 inches; sodic within a depth of 30 inches

Land capability classification, nonirrigated: 6s

Ecological site number and name: R080AY091OK, Slickspot PE 44-64

Typical profile:

A—0 to 9 inches; loam

Btn—9 to 18 inches; silty clay

Btnz—18 to 50 inches; silty clay loam

Cr—50 to 61 inches; bedrock

Additional Components

Grainola soils: 8 percent of the map unit

Lucien soils: 8 percent of the map unit

Foard soils: 7 percent of the map unit

Stephenville soils: 7 percent of the map unit

Zv—Cyril fine sandy loam, 0 to 1 percent slopes,

occasionally flooded

Map Unit Setting

Major land resource area: 80A

Elevation: 700 to 2,200 feet

Mean annual precipitation: 22 to 40 inches

Mean annual air temperature: 57 to 64 degrees F

Frost-free period: 185 to 240 days

Major Component Description

Cyril

Extent: 80 percent of the map unit

Geomorphic setting: Flood plains in river valleys

Parent material: Calcareous, loamy alluvium

Slope: 0 to 1 percent

Surface runoff class: Negligible

Soil depth: Greater than 60 inches

Slowest permeability class of the soil to a depth of 60 inches or above a restrictive

layer: Moderate

Slowest permeability class within a depth of 80 inches: Moderate

Drainage class: Well drained

Available water capacity: About 8.5 inches

Depth to the top of the seasonal high water table: Greater than 6 feet

Flooding: Occasional

Ponding: None

Land capability classification, nonirrigated: 2w

Ecological site number and name: R080AY050OK, Loamy Bottomland PE 44-64

Typical profile:

A—0 to 18 inches; fine sandy loam

C—18 to 80 inches; loam
Supplement to the Soil Survey of Comanche County, Oklahoma

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Additional Components

Gracemont soils: 5 percent of the map unit

Gracemore soils: 5 percent of the map unit

Yahola soils: 5 percent of the map unit

Pulaski soils: 4 percent of the map unit

Ezell soils: 1 percent of the map unit
59

For general and detailed information regarding the use and management of the

map units in this survey, see the soil reports and report descriptions on the Web

Soil Survey at http://websoilsurvey.nrcs.usda.gov. A soil survey is an inventory

and evaluation of the soils in the survey area. It can be used to adjust land uses

to the limitations and potentials of natural resources and the environment. Also, it

can help to prevent soil-related failures in land uses.

In preparing a soil survey, soil scientists, conservationists, engineers, and

others collect extensive field data about the nature and behavioral characteristics

of the soils. They collect data on erosion, droughtiness, flooding, and other

factors that affect various soil uses and management. Field experience and

collected data on soil properties and performance are used as a basis in

predicting soil behavior.

Information developed during a soil survey can be used to plan the use and

management of soils for crops and pasture; as rangeland and woodland; as sites

for buildings, sanitary facilities, highways and other transportation systems, and

parks and other recreational facilities; and for wildlife habitat. It can be used to

identify the potentials and limitations of each soil for specific land uses and to

help prevent construction failures caused by unfavorable soil properties.

Interpretive ratings help engineers, planners, and others understand how soil

properties influence important nonagricultural uses, such as building site

development and construction materials. The ratings indicate the most restrictive

soil features affecting the suitability of the soils for these uses.

Soils are rated in their natural state. Only normal practices for the rated use are

considered. Unusual modifications to the site or soil material are not considered

in the ratings. Where soils have limitations, engineers and others may be able to

modify soil features or adjust the plans for a structure to compensate for most of

the limitations. Most of these modifications, however, are costly. The final decision

in selecting a site for a particular use generally involves weighing the costs of site

preparation and maintenance.

Planners and others using soil survey information can evaluate the effect of

specific land uses on productivity and on the environment in all or part of the

survey area. The survey can help planners to maintain or create a land use

pattern in harmony with the natural soil.

Contractors can use a survey to locate sources of sand, gravel, roadfill, and

topsoil. They can use it to identify areas where bedrock, wetness, or very firm soil

layers can cause difficulty in excavation.

Health officials, highway officials, engineers, and others may also find a soil

survey useful. The survey can help them plan the safe disposal of wastes and

locate sites for pavements, sidewalks, campgrounds, playgrounds, lawns, and

trees and shrubs.

Use and Management of the Soils
Supplement to the Soil Survey of Comanche County, Oklahoma

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Rangeland

Mark Moseley, range conservationist, Natural Resources Conservation Service, helped prepare this

section.

Range, grazed forestland, and native pasture provide forage for livestock in the

survey area.

Range is defined as land on which the native vegetation (the climax, or natural

potential, plant community) is predominantly grasses, grasslike plants, forbs, and

shrubs suitable for grazing and browsing. Range includes natural grasslands,

savannas, many wetlands, some deserts, tundra, and certain shrub and forb

communities. Range receives no regular or frequent cultural treatment. The

composition and production of the plant community are determined by soil, climate,

topography, overstory canopy, and grazing management.

Grazed forestland is defined as land on which the understory includes, as an

integral part of the forest plant community, plants that can be grazed without

significant impairment of other forest values.

Native pasture is defined as land on which the potential (climax) vegetation is

forest but which is used and managed primarily for the production of native forage

plants. Native pasture includes cutover forestland and forestland that has been

cleared and is managed for native or naturalized forage plants.

Approximately 75 percent of the annual production on rangeland grows in April,

May, and June, coinciding with spring rains and moderate temperatures. A secondary

growth period generally occurs in September and October, coinciding with fall rains

and cooling temperatures.

Most of the local ranches and livestock farms are cow-calf operations. There are

also some pure stocker enterprises and some ranches that diversify their cow-calf

operation with stockers to provide greater flexibility.

Several livestock operations supplement the grazing of native rangeland with

introduced grasses, such as bermudagrass and “plains” bluestem. Forage crops are

also used. Protein, hay, and small-grain crops are used to supplement livestock

through winter.

Droughts of varying lengths occur, and short-term summer droughts are common.

Longer periods of drought, some lasting several months, are also frequent.

The pre-settlement vegetation evolved with periodic natural fires, droughts,

migratory grazing by bison, and impact from many other wildlife species. The bison

would heavily impact an area and then move to other grazing range.

Early settlement brought continuous grazing and eliminated much of the highquality vegetation on some ecological sites. Areas that were once open-savannah

ecological sites with a mixture of grasses, forbs, and scattered trees are now covered

with oaks, a few tall and mid grasses, and low successional grasses and forbs. Some

prairie sites are now growing low successional grasses and forbs instead of tall

grasses. The amount of forage presently produced may be less than half of that

originally produced. On some sites, the number of eastern redcedar has increased

significantly due to a lack of prairie fires. Remnants of the original plant species are

still found on most rangeland, however, and progressive grazing management can

allow these high quality plants to re-establish without reseeding.

The table “Rangeland Productivity and Characteristic Plant Communities” is

available on the Soil Data Mart at http://soildatamart.nrcs.usda.gov. This table shows,

for each soil, the ecological site; the total annual production of vegetation in

favorable, normal, and unfavorable years; the characteristic vegetation; and the

average percentage of each species. Only those soils that are used as rangeland or

are suited to use as rangeland are listed. Explanation of the column headings in this

table follows.
Supplement to the Soil Survey of Comanche County, Oklahoma

61

An ecological site for rangeland is a distinctive kind of land and vegetation with

specific physical characteristics that makes it different from other kinds of land in its

ability to produce a distinctive kind and amount of vegetation.

Many different ecological sites are in the survey area. Over time, the combination

of plants best suited to a particular soil and climate has become dominant. If the soil

is not excessively disturbed, this group of plants is the natural plant community for the

site. Natural plant communities are not static but vary slightly from year to year and

place to place.

The relationship between soils and vegetation was ascertained during this survey;

thus, ecological sites generally can be determined directly from the soil map. Soil

properties that affect moisture supply and plant nutrients have the greatest influence

on the productivity of range plants. Soil reaction, salt content, and a seasonal high

water table are also important. The “Electronic Field Office Technical Guide,” which is

available at the local office of the Natural Resources Conservation Service or online

at http://www.nrcs.usda.gov/technical/efotg/, can provide specific information about

ecological sites.

Total production is the amount of vegetation that can be expected to grow

annually on well managed rangeland. It includes all vegetation, whether or not it is

palatable to grazing animals. It includes the current year’s growth of leaves, twigs,

and fruit of woody plants. It does not include the increase in stem diameter of

trees and shrubs. It is expressed in pounds per acre of air-dry vegetation for

favorable, normal, and unfavorable years. In a favorable year, the amount and

distribution of precipitation and the temperatures make growing conditions

substantially better than average. In a normal year, growing conditions are near

the historical monthly average. In an unfavorable year, growing conditions are

well below average, generally because of low available soil moisture. Figure 2

shows a typical growth curve that represents the percentage of total growth that

occurs each month for native vegetation and other forage. Dry weight is the total

annual yield per acre of air-dry vegetation. Yields are adjusted to a percent of airdry moisture content. The relationship of green weight to air-dry weight varies

according to such factors as stage of maturity, exposure, amount of shade, recent

rains, and unseasonable dry periods.

Characteristic vegetation consists of the grasses, forbs, and shrubs that make up

most of the potential natural plant community on each soil. The plants are listed by

common name. Under composition, the anticipated percentage of the total annual

production is given for each species making up the characteristic vegetation. The

amount that can be used as forage depends on the kinds of grazing animals and on

the grazing season.

Similarity Index

The similarity index indicates on a percentage basis the extent to which the

present plant community resembles a specified vegetative state on an ecological site.

The Natural Resources Conservation Service uses similarity index two ways.

The first use compares the present vegetation on an ecological site to the

presumed historic vegetation for that site. A similarity index of 70 would suggest that

the present plant community contains 70 percent of the presumed historic plant

community for that site. This comparison provides a basis for examining the extent

and direction of changes between current vegetation and historic vegetation.

The second use measures how near the current plant community is to the

landowners goal for the land. The management goal for rangeland is not necessarily

a similarity index of 100 as compared to the historic plant community. Therefore, the

similarity index can represent the percentage of the plant community that resembles

a desired plant community.
Supplement to the Soil Survey of Comanche County, Oklahoma

62

Abnormal disturbances that change the natural plant community include repeated

overuse by livestock, excessive burning, erosion, and cultivation. Grazing animals

select the most palatable plants. These plants eventually die if they are continually

grazed at a severity that does not allow for recovery. A very severe disturbance can

completely destroy the natural community. Under such conditions, the less desirable

plants, such as annuals and weed-like plants, can increase in abundance. If the plant

community and the soils have not deteriorated significantly and proper range

management is applied, the site can eventually return to predominantly natural plants.

Knowledge of the ecological site is necessary as a basis for planning and applying

the management needed to maintain or improve the desired plant community for

selected uses. Such information is needed to support management objectives,

planned grazing systems, stocking rates, and wildlife management practices; to

improve the potential of an area for recreational uses; and to improve the condition of

watersheds.

Rangeland Management

Rangeland management requires a knowledge of the kinds of soil in an area and

of the potential natural plant community. It also requires an evaluation of the similarity

index.

Effective range management conserves rainfall, enhances water quality, reduces

the hazard of downstream flooding, improves yields, provides forage for livestock and

wildlife, enhances recreational opportunities, and protects the soil. The main

management concern is recognizing important changes in the plant cover or the

range trend. These changes occur gradually and can be overlooked.

Each range manager should evaluate the type of plant community that best

supports the ranch and then apply management and ecological principles to

achieve the goals. The desired plant community should be within the capabilities

of the land.

Figure 2.—Typical growth curves for various kinds of forage in the survey area. The growth curve

for each kind of forage indicates the percentage of the total annual growth that occurs each

month.
Supplement to the Soil Survey of Comanche County, Oklahoma

63

The range management practices used in the county include prescribed grazing,

stock-water developments, and fences. If undesirable plants become dominant,

range seeding, brush management, or prescribed burning are commonly used.

Range management includes four major considerations:

• Grazing distribution, which is achieved by managing livestock to graze all parts

of the grazing unit equally.

• Selective grazing, which occurs because animals graze preferred plants to

balance their diets. If selective grazing occurs repeatedly, the preferred plants

are damaged.

• Proper stocking rates, which are achieved by balancing animal numbers with

forage production.

• Rest periods, during which grazed plants are given enough rest to recover and

to maintain growth.

An important principle of range management is that forage production is controlled

by rainfall while composition is determined by grazing management.

The setting of stocking rates is not an exact science because of influences from

grazing management, season of use, mix of livestock, and seasonal production of

forage. Some general rules, however, can be helpful. To maintain a nutritional cover

of plants, about 50 percent of the annual growth of the most important grazing plants

should remain at the end of the grazing season. Plants can be removed not only

through grazing by livestock but also through grazing by rodents, insects, and wildlife

and through the deterioration caused by climatic variations. Because of these factors,

a safe initial stocking rate for livestock should be calculated on the basis of 25

percent of the total annual growth, by weight, of the vegetation.

For example, production could be 3,500 pounds per acre of air-dry grasses, forbs,

and limited woody species for an average season on a Loamy Prairie ecological site

with a similarity index of 70 to the historic plant community. Twenty-five percent of this

production would be 875 pounds per acre.

A 1,000-pound cow and her calf is equivalent to one animal unit (AU) and consume

about 2.6 percent of her body weight (26 pounds) of forage per day. Therefore, in 1

month an animal unit could consume 790 pounds of native vegetation, depending on

the quality and stage of growth of the plants (26 pounds per day times 365 days per

year divided by 12 months per year).

Dividing 875 pounds (the forage allocation) by 26 pounds (the forage required per

day for 1 animal unit) suggests that 1 acre of Loamy Prairie ecological site with a

similarity index of 70 would feed 1 cow and calf for 33.6 days. To convert forage

available from 1 acre to animal unit months (AUM), the available forage (875 pounds)

is divided by the amount required to feed 1 animal unit for 1 month (790 pounds).

Therefore, 1 acre would provide 1.1 AUM of grazing and 10.9 acres would feed 1 cow

and calf for 12 months.

Another approach is to calculate the annual forage needs of an animal unit (790

pounds per month times 12 months equals 9,490 pounds). Dividing the 875 pounds

of usable forage per acre into the 9,490 pounds needed by the cow and calf reveals

that approximately 10.9 acres is needed for 1 cow annually. Stocking rate calculations

should be adjusted for animal size, grazing system, and grazing season.

More information about planning a grazing program is available from the local

office of the Natural Resources Conservation Service.

Ecological Site Descriptions

Twenty-eight ecological sites are recognized in Comanche County. The ecological

site identifier has eleven characters. The “R” indicates an ecological site. The next

four characters identify the major land resource area. The sixth character identifies

the major land resource unit subdivision. The next three characters identify the
Supplement to the Soil Survey of Comanche County, Oklahoma

64

individual ecological site number. The final two characters identify the state. The

identifier is followed by the proper name for the ecological site. The following

descriptions include a list of the plants that are characteristic of the sites. Detailed

ecological site descriptions are available at the local office of the Natural Resources

Conservation Service.

R078CY031OK, Clay Prairie (South) PE 32-44.—This site is in areas of rolling,

broken topography with some gentle slopes. The soils are red clay. The historic climax

vegetation includes sideoats grama, buffalograss, silver bluestem, tobosagrass, hairy

grama, and slim tridens. Woody species include mesquite and pricklypear.

R078CY038OK, Gyp PE 32-44.—This site is on upland prairies that have gypsum

outcrops and shallow gyp beds. The historic climax vegetation includes little

bluestem, blue grama, sideoats grama, slim tridens, hairy tridens, and sand

dropseed. Forbs include hairy goldenaster and false broomweed.

R078CY042OK, Hardland (South) PE 32-44.—This site is in areas of deep,

productive, slowly permeable, clayey soils on upland prairies. The historic climax

vegetation includes sand bluestem, little bluestem, switchgrass, western wheatgrass,

sideoats grama, blue grama, vine mesquite, and meadow dropseed. Woody species

include mesquite.

R078CY050OK, Loamy Bottomland PE 32-44.—This site is in level to gently

sloping areas on bottomlands along larger drainageways. It is subject to occasional

overflow from streams and runoff from hillsides. The historic climax vegetation

includes sand bluestem, big bluestem, switchgrass, little bluestem, Indiangrass,

western wheatgrass, vine mesquite, tall dropseed, eastern gamagrass, tall dropseed,

Canada wildrye, and sideoats grama.

R078CY065OK, Clay Prairie (North) PE 32–44.—This site was formerly named

Red Clay Prairie. It is in areas of rolling and broken topography that has some gentle

slopes. The historic climax vegetation includes little bluestem, sideoats grama, hairy

grama, and slim tridens.

R078CY066OK, Shallow Clay Prairie PE 32-44.—This site is in areas of rolling

and broken topography that has some gentle slopes. The site is overblown by sand.

The historic climax vegetation includes sideoats grama, little bluestem, tall dropseed,

western wheatgrass, blue grama, hairy grama, buffalograss, slim tridens, and silver

bluestem. Forbs include heath aster, western ragweed, Louisiana sagewort, and

annual broomweed. Woody species include pricklypear and junipers.

R078CY084OK, Shallow Prairie (South) PE 32-44.—This site is in areas where

dolomitic limestone beds are interbedded with red clays. The topography is smooth to

rolling. The historic climax vegetation includes little bluestem, sideoats grama, hairy

grama, composite dropseed, big bluestem, Indiangrass, switchgrass, and Canada

wildrye. Legumes include rushpea, prairie clover, prairie bundleflower, and catclaw

sensitive-briar. Forbs include Maximilian sunflower, compassplant, purple coneflower,

leadplant, and tall blazing star. Woody species include skunkbush sumac, roughleaf

dogwood, and winged sumac.

R078CY091OK, Slickspot PE 32-44.—This site is in crusted, upland alkali spots.

It is typically intermingled with areas of Claypan Prairie and Loamy Prairie. The

historic climax vegetation includes alkali sacaton, switchgrass, white tridens, tall

dropseed, blue grama, dropseed, purple threeawn, mourning lovegrass, gummy

lovegrass, and fall witchgrass. Legumes include yellow neptune. Forbs include

rhombopod, pricklypear, curlycup gumweed, wax goldenweed, and hairy goldenaster.

R078CY842OK, Eroded Hardland PE 32-44.—This site is in areas where part or

all of the A horizon has been removed by erosion. The soil integrity has been

changed. Because of the past erosion and the probability of ongoing erosion, the

plant community can be determined only by onsite inspection. The productivity of this

site has not been determined. See R078CY042OK, Hardland (South) PE 32-44, for

the historic climax vegetation on the parent site.
Supplement to the Soil Survey of Comanche County, Oklahoma

65

R078CY865OK, Eroded Clay Prairie PE 32-44.—This site is in areas where part

or all of the A horizon has been removed by erosion. The soil integrity has been

changed. Because of the past erosion and the probability of ongoing erosion, the

plant community can be determined only by onsite inspection. The productivity of this

site has not been determined. See R078CY065OK, Clay Prairie (North) PE 32-44, for

the historic climax vegetation on the parent site.

R080AY001OK, Alkali Bottomland PE 44-64.—This site is in areas of level to

gently sloping, somewhat poorly drained soils on bottomlands. The historic climax

vegetation includes alkali sacaton, western wheatgrass, vine mesquite, inland

saltgrass, switchgrass, and eastern gamagrass. Forbs include narrowleaf

rhombopod, catclaw sensitive-brier, yellow neptunia, dotted gayfeather, ironweed,

curlycup gumweed, curly dock, seacoast sumpweed, western ragweed, yellow thistle,

common yarrow, and white heath aster. Shrubs and woody plants include pricklypear,

honey mesquite, American elm, black willow, and willow baccharis.

R080AY011OK, Claypan Prairie (South) PE 44-64.—This site is in areas of deep,

nearly level to gently sloping soils on uplands. The historic climax vegetation includes

switchgrass, little bluestem, big bluestem, Indiangrass, sideoats grama, dropseed

species, blue grama, hairy grama, and Canada wildrye. Forbs include leadplant,

yellow neptunia, prairie clover, western ragweed, scurfpea, green antelopehorn,

Illinois bundleflower, pitcher sage, common yarrow, Louisiana sagewort, heath aster,

wavyleaf thistle, mare’s-tail, Texas croton, and daisy fleabane. Shrubs and vines

include honey locust, pricklypear, and honey mesquite.

R080AY045OK, Heavy Bottomland PE 44-64.—This site is on bottomlands. The

soils are clayey and droughty but are excessively wet during periods of high rainfall.

The historic climax vegetation includes switchgrass, prairie cordgrass, Virginia

wildrye, western wheatgrass, vine mesquite, buffalograss, longspike tridens, white

tridens, and Texas wintergrass. Woody species include mesquite.

R080AY050OK, Loamy Bottomland PE 44-64.—This site is on flood plains or

terraces. The soils are nearly level to sloping, loamy, and very deep. They are subject

to stream overflow and runoff from hillsides. The historic climax vegetation includes

big bluestem, switchgrass, Indiangrass, eastern gamagrass, Florida paspalum, and

little bluestem. Cool-season grasses include Canada wildrye, Virginia wildrye, Texas

bluegrass, and western wheatgrass. Forbs include Maximilian sunflower, stiff

sunflower, and Jerusalem artichoke. Woody species include elm, willow, pecan, oak,

cottonwood, green ash, and coralberry.

R080AY056OK, Loamy Prairie PE 44-64.—This site is in areas of deep, loamy

soils on uplands. The historic climax vegetation includes little bluestem, big bluestem,

Indiangrass, switchgrass, Canada wildrye, sideoats grama, and blue grama.

Legumes include leadplant, wild indigo, scurfpea, and prairie acacia. Woody species

are rare.

R080AY083OK, Shallow Prairie PE 44-64.—This site is in areas of gently sloping

to moderately steep, shallow soils in prairies. Rock outcrop is common on the surface

and typically covers 15 to 20 percent of the area. The historic climax vegetation

includes little bluestem, big bluestem, Indiangrass, switchgrass, dropseed species,

and Scribner’s panicum. Legumes include catclaw sensitive-brier, Illinois bundleflower,

Virginia tephrosia, leadplant, and white, purple, and roundhead prairie clovers.

R080AY091OK, Slickspot PE 44-64.—This site is on uplands in areas of level to

gently sloping, deep, loamy soils that have a clayey, blocky, alkali subsoil. The

historic climax vegetation includes alkali sacaton, switchgrass, western wheatgrass,

tall dropseed, white tridens, blue grama, dropseed, gummy lovegrass, fall witchgrass,

yellow neptunia, mourning lovegrass, and purple threeawn. Forbs include dotted

gayfeather, curly cup gumweed, goldenweed, and hairy goldenaster.

R080AY856OK, Eroded Loamy Prairie PE 44-64.—This site is in areas where

part or all of the A horizon has been removed by erosion. The soil integrity has been
Supplement to the Soil Survey of Comanche County, Oklahoma

66

changed. Because of the past erosion and the probability of ongoing erosion, the

plant community can be determined only by onsite inspection. The productivity of this

site has not been determined. See R080AY056OK, Loamy Prairie PE 44-64, for the

historic climax vegetation on the parent site.

R082BY004OK, Boulder Ridge Savannah PE 38-48.—This site is on the lower

slopes and ridges near the Wichita Mountains. The soils are deep, are gravelly, and

have small rocks on or near the surface. The historic climax vegetation is dominantly

big bluestem, Indiangrass, switchgrass, and little bluestem with lesser amounts of

sideoats grama, blue grama, hairy grama, wildrye, dropseed, and forbs. Some areas

have a few woody species, including post oak and blackjack oak.

R082BY048OK, Limestone Ridge PE 38-48.—This site is on hills and ridges,

mostly to the north of the Wichita Mountains. The historic climax vegetation includes

big bluestem, Indiangrass, little bluestem, switchgrass, sideoats grama, hairy grama,

tall grama, blue grama, slim tridens, hairy tridens, and tall dropseed. Woody species

include skunkbush and pricklypear cactus.

R082BY056OK, Loamy Prairie PE 38-48.—This site is in areas of productive,

deep, loamy soils on uplands. The historic climax vegetation includes little bluestem,

sand bluestem, switchgrass, and Indiangrass with an understory of sideoats grama,

western wheatgrass, blue grama, and buffalograss. Legumes include leadplant,

Illinois bundleflower, and scurfpea. Forbs include Maximilian sunflower, Louisiana

sagewort, and heath aster.

R082BY856OK, Eroded Loamy Prairie PE 38-48.—This site is on uplands in

areas of nearly level to moderately steep, coarse textured soils where part or all of

the A horizon has been removed by erosion. The soil integrity has been changed.

Because of the past erosion and the probability of ongoing erosion, the plant

community can be determined only by onsite inspection. The productivity of this site

has not been determined. See R082BY056OK, Loamy Prairie PE 38-48, for the

historic climax vegetation on the parent site.

R084AY018OK, Deep Sand Savannah PE 48-64.—This site is in areas of nearly

level to moderately steep, coarse textured soils on uplands. The historic climax

vegetation includes big bluestem, sand bluestem, Indiangrass, little bluestem,

switchgrass, broadleaf uniola, beaked panicum, purpletop, tall dropseed, Scribner’s

panicum, and sand lovegrass. Woody species include post oak, blackjack oak,

hickory, winged elm, and persimmon.

R084AY075OK, Sandy Savannah PE 44-64.—This site is in areas of gently

sloping to steep fine sandy loams that support mid grasses and tall grasses mixed

with an overstory of oak. The historic climax vegetation includes sand bluestem, little

bluestem, Indiangrass, switchgrass, and sideoats grama. Forbs include Maximilian

sunflower, ashy sunflower, stiff sunflower, compassplant, daisy fleabane, goldenrods,

and numerous other species in trace amounts. Woody species include post oak,

blackjack oak, and hickory.

R084AY095OK, Subirrigated PE 48-64.—This site is on uplands and flood plains.

The soils are deep, nearly level to very gently sloping, and sandy. They have a high

water table. The historic climax vegetation includes switchgrass, big bluestem,

Indiangrass, and eastern gamagrass. Woody species include willow and cottonwood.

R084AY818OK, Eroded Deep Sand Savannah PE 48-64.—This site is in areas

where part or all of the A horizon has been removed by erosion. The soil integrity has

been changed. Because of the past erosion and the probability of ongoing erosion,

the plant community can be determined only by onsite inspection. The productivity of

this site has not been determined. See R084AY018OK, Deep Sand Savannah PE 48-

64, for the historic climax vegetation on the parent site.

R084AY876OK, Eroded Sandy Savannah PE 48-64.—This site is in areas where

part or all of the A horizon has been removed by erosion. The soil integrity has been

changed. Because of the past erosion and the probability of ongoing erosion, the
Supplement to the Soil Survey of Comanche County, Oklahoma

67

plant community can be determined only by onsite inspection. The productivity of this

site has not been determined. See R084AY075OK, Sandy Savannah PE 44-64, for

the historic climax vegetation on the parent site.

R084BY076OK, Sandy Savannah PE 44-64.—This site is in areas of gently

sloping to steep, sandy soils that support mid grasses and tall grasses mixed with

post oak, blackjack oak, and associated woody vegetation. The historic climax

vegetation includes little bluestem, Indiangrass, big bluestem, switchgrass, Canada

wildrye, Virginia wildrye, Texas bluegrass, and flatsedge species. Woody species

include post oak, blackjack oak, hickory, ash, elm, bumelia, coralberry, persimmon,

poison ivy, grape, and hackberry.

R085XY026OK, Edgerock PE 56-66.—This site is in areas of rolling limestone

hills where exposed bedrock has uplifted to form characteristic limestone rows on the

surface. The historic climax vegetation includes little bluestem, Indiangrass, big

bluestem, switchgrass, sideoats grama, hairy grama, Scribner’s panicum, meadow

dropseed, a few forbs, and woody species.

69

This section summarizes the major factors of soil formation and describes the

system of soil classification. The classification of each soil in the survey area is

shown in the table “Classification of the Soils” at the end of this section. The Official

Soil Series Descriptions, including the range of important characteristics of the soils,

for the series in this survey area are online at http://soils.usda.gov/technical/

classification/osd/. Characteristics of the soil and the material in which it formed are

identified for each soil series. A pedon, a small three-dimensional area of soil, which

is typical of the series is described. The detailed description of each soil horizon

follows standards in the “Soil Survey Manual” (Soil Survey Division Staff, 1993). Many

of the technical terms used in the descriptions are defined in “Soil Taxonomy” (Soil

Survey Staff, 1999).

Formation of the Soils

Soil is produced by the action of soil-forming processes on materials deposited or

accumulated by geologic agencies. The characteristics of the soil at any given point

are determined by the physical and mineralogical composition of the parent materials;

the climate under which the soil material has accumulated and existed since

accumulation; the plant and animal life on and in the soil; the relief, or lay of the land;

and the length of time the forces of soil development have acted on the soil material.

Climate and vegetation are the active factors of soil formation. They act on parent

material that has accumulated through the weathering of rocks and slowly change it

into a natural body that has genetically related horizons. The effects of climate and

vegetation are conditioned by relief. Parent material also affects the kind of profile

that can be formed and, in extreme cases, determines it almost entirely. Finally, time

is needed for the changing of the parent material into a soil profile. The time may be

long or short, but some time is always required for differentiation of horizons.

Generally, a long time is required for the development of distinct horizons.

The factors of soil formation are so closely interrelated in their effects that few

generalizations can be made regarding the effects of any one unless conditions are

specified for the other four.

Classification of the Soils

The system of soil classification used by the National Cooperative Soil Survey has

six categories (Soil Survey Staff, 1999 and 2003). Beginning with the broadest, these

categories are the order, suborder, great group, subgroup, family, and series.

Classification is based on soil properties observed in the field or inferred from those

observations or from laboratory measurements. The categories are described in the

following paragraphs.

ORDER. Twelve soil orders are recognized. The differences among orders reflect

the dominant soil-forming processes and the degree of soil formation. Each order is

identified by a word ending in sol. An example is Mollisol.

Formation and Classification

of the Soils
Supplement to the Soil Survey of Comanche County, Oklahoma

70

SUBORDER. Each order is divided into suborders primarily on the basis of

properties that influence soil genesis and are important to plant growth or properties

that reflect the most important variables within the orders. The last syllable in the

name of a suborder indicates the order. An example is Ustoll (Ust, meaning dry, plus

oll, from Mollisol).

GREAT GROUP. Each suborder is divided into great groups on the basis of close

similarities in kind, arrangement, and degree of development of pedogenic horizons;

soil moisture and temperature regimes; and base status. Each great group is

identified by the name of a suborder and by a prefix that indicates a property of the

soil. An example is Argiustolls (Argi, meaning argillic horizonation, plus ustoll, the

suborder of the Mollisols that has an ustic moisture regime).

SUBGROUP. Each great group has a typic subgroup. Other subgroups are

intergrades or extragrades. The typic is the central concept of the great group; it is

not necessarily the most extensive. Intergrades are transitions to other orders,

suborders, or great groups. Extragrades have some properties that are not

representative of the great group but do not indicate transitions to any other known

kind of soil. Each subgroup is identified by one or more adjectives preceding the

name of the great group. The adjective Typic identifies the subgroup that typifies the

great group. An example is Typic Argiustolls.

FAMILY. Families are established within a subgroup on the basis of physical and

chemical properties and other characteristics that affect management. Generally, the

properties are those of horizons below plow depth where there is much biological

activity. Among the properties and characteristics considered are particle-size class,

mineral content, temperature regime, thickness of the root zone, consistence,

moisture equivalent, slope, and permanent cracks. A family name consists of the

name of a subgroup preceded by terms that indicate soil properties. An example is

fine, mixed, superactive, thermic Typic Argiustolls.

SERIES. The series consists of soils that have similar horizons in their profile.

The horizons are similar in color, texture, structure, reaction, consistence, mineral

and chemical composition, and arrangement in the profile. The texture of the surface

layer or of the substratum can differ within a series.
Supplement to the Soil Survey of Comanche County, Oklahoma

71

Table 5.--Classification of the Soils

______________________________________________________________________________________________________

 |

 Soil name | Family or higher taxonomic class

__________________________|___________________________________________________________________________

 |

 Acme---------------------|Fine-silty, mixed, superactive, thermic Gypsic Calciustolls

 Ashport------------------|Fine-silty, mixed, superactive, thermic Fluventic Haplustolls

 Bathel-------------------|Fine-loamy, mixed, superactive, thermic Aquic Hapludalfs

 Bocox--------------------|Loamy, mixed, active, thermic Aquic Arenic Hapludalfs

 Brico--------------------|Clayey-skeletal, mixed, active, thermic Typic Argiustolls

 Clairemont---------------|Fine-silty, mixed, superactive, calcareous, thermic Typic Ustifluvents

 Cornick------------------|Loamy, mixed, superactive, thermic Lithic Haplustolls

 Cyril--------------------|Coarse-loamy, mixed, superactive, thermic Cumulic Haplustolls

 Derby--------------------|Mixed, thermic Lamellic Ustipsamments

 Dougherty----------------|Loamy, mixed, active, thermic Arenic Haplustalfs

 Easpur-------------------|Fine-loamy, mixed, superactive, thermic Fluventic Haplustolls

 Eufaula------------------|Siliceous, thermic Psammentic Paleustalfs

 Ezell--------------------|Sandy, mixed, thermic Aeric Fluvaquents

 Foard--------------------|Fine, smectitic, thermic Vertic Natrustolls

 Gracemont----------------|Coarse-loamy, mixed, superactive, calcareous, thermic Oxyaquic Udifluvents

 Gracemore----------------|Sandy, mixed, thermic Oxyaquic Udifluvents

 Grainola-----------------|Fine, mixed, active, thermic Udertic Haplustalfs

 Grant--------------------|Fine-silty, mixed, superactive, thermic Udic Argiustolls

 Hibsaw-------------------|Fine-silty, mixed, superactive, nonacid, thermic Aeric Halaquepts

 Hinkle-------------------|Fine, smectitic, thermic Vertic Natrustalfs

 Hollister----------------|Fine, smectitic, thermic Typic Haplusterts

 Huska--------------------|Fine, mixed, superactive, thermic Mollic Natrustalfs

 Indiahoma----------------|Fine, smectitic, thermic Typic Haplusterts

 Kiti---------------------|Loamy-skeletal, mixed, superactive, thermic Lithic Haplustolls

 Knoco--------------------|Clayey, mixed, active, calcareous, thermic, shallow Aridic Ustorthents

 Konawa-------------------|Fine-loamy, mixed, active, thermic Ultic Haplustalfs

 Lawton-------------------|Fine, mixed, superactive, thermic Typic Argiustolls

 Lebron-------------------|Clayey over sandy or sandy-skeletal, mixed, superactive, thermic

 | Fluvaquentic Hapludolls

 Lela---------------------|Fine, mixed, superactive, thermic Udic Haplusterts

 Lucien-------------------|Loamy, mixed, superactive, thermic, shallow Udic Haplustolls

 Mclain-------------------|Fine, mixed, superactive, thermic Pachic Argiustolls

 Meno---------------------|Loamy, mixed, superactive, thermic Aquic Arenic Haplustalfs

 Miller-------------------|Fine, mixed, superactive, thermic Udertic Haplustolls

 Minco--------------------|Coarse-silty, mixed, superactive, thermic Udic Haplustolls

 Newalla------------------|Fine-loamy over clayey, siliceous, superactive, thermic Udic Haplustalfs

 Norge--------------------|Fine-silty, mixed, active, thermic Udic Paleustolls

 Oscar--------------------|Fine-silty, mixed, superactive, thermic Typic Natrustalfs

 Pond Creek---------------|Fine-silty, mixed, superactive, thermic Pachic Argiustolls

 Port---------------------|Fine-silty, mixed, superactive, thermic Cumulic Haplustolls

 Pulaski------------------|Coarse-loamy, mixed, superactive, nonacid, thermic Udic Ustifluvents

 Renfrow------------------|Fine, mixed, superactive, thermic Udertic Paleustolls

 Retrop-------------------|Fine-silty, mixed, superactive, calcareous, thermic Oxyaquic Udifluvents

 Roscoe-------------------|Fine, smectitic, thermic Typic Haplusterts

 Somervell----------------|Loamy-skeletal, carbonatic, thermic Typic Calciustolls

 Stamford-----------------|Fine, smectitic, thermic Chromic Haplusterts

 Stephenville-------------|Fine-loamy, siliceous, active, thermic Ultic Haplustalfs

 Tillman------------------|Fine, mixed, superactive, thermic Vertic Paleustolls

 Tribbey------------------|Coarse-loamy, mixed, superactive, nonacid, thermic Oxyaquic Udifluvents

 Vanoss-------------------|Fine-silty, mixed, superactive, thermic Udic Argiustolls

 Vernon-------------------|Fine, mixed, active, thermic Typic Haplustepts

 Waurika------------------|Fine, smectitic, thermic Vertic Argialbolls

 Wheatwood----------------|Fine-silty, mixed, active, thermic Fluventic Haplustepts

 Windthorst---------------|Fine, mixed, active, thermic Udic Paleustalfs

 Yahola-------------------|Coarse-loamy, mixed, superactive, calcareous, thermic Udic Ustifluvents

 Zaneis-------------------|Fine-loamy, siliceous, active, thermic Udic Argiustolls

__________________________|___________________________________________________________________________

73

Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.

U.S. Department of Agriculture Handbook 18. http://soils.usda.gov/technical/

Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for

making and interpreting soil surveys. 2nd edition. Natural Resources

Conservation Service. U.S. Department of Agriculture Handbook 436.

http://soils.usda.gov/technical/

Soil Survey Staff. 2003. Keys to soil taxonomy. 9th edition. U.S. Department of

Agriculture, Natural Resources Conservation Service. http://soils.usda.gov/

technical/

United States Department of Agriculture. 1967. Soil survey of Comanche County,

Oklahoma.

References

75

Many of the terms relating to landforms, geology, and geomorphology are defined

in more detail in the “National Soil Survey Handbook” (available at local offices of the

Natural Resources Conservation Service or on the Internet).

ABC soil. A soil having an A, a B, and a C horizon.

AC soil. A soil having only an A and a C horizon. Commonly, such soil formed in

recent alluvium or on steep, rocky slopes.

Aeration, soil. The exchange of air in soil with air from the atmosphere. The air in a

well aerated soil is similar to that in the atmosphere; the air in a poorly aerated

soil is considerably higher in carbon dioxide and lower in oxygen.

Aggregate, soil. Many fine particles held in a single mass or cluster. Natural soil

aggregates, such as granules, blocks, or prisms, are called peds. Clods are

aggregates produced by tillage or logging.

Alkali (sodic) soil. A soil having so high a degree of alkalinity (pH 8.5 or higher) or

so high a percentage of exchangeable sodium (15 percent or more of the total

exchangeable bases), or both, that plant growth is restricted.

Alluvial fan. A low, outspread mass of loose materials and/or rock material,

commonly with gentle slopes. It is shaped like an open fan or a segment of a

cone. The material was deposited by a stream at the place where it issues from a

narrow mountain valley or upland valley or where a tributary stream is near or at

its junction with the main stream. The fan is steepest near its apex, which points

upstream, and slopes gently and convexly outward (downstream) with a gradual

decrease in gradient.

Alluvium. Unconsolidated material, such as gravel, sand, silt, clay, and various

mixtures of these, deposited on land by running water.

Alpha,alpha-dipyridyl. A compound that when dissolved in ammonium acetate is

used to detect the presence of reduced iron (Fe II) in the soil. A positive

reaction implies reducing conditions and the likely presence of redoximorphic

features.

Animal unit month (AUM). The amount of forage required by one mature cow of

approximately 1,000 pounds weight, with or without a calf, for 1 month.

Aquic conditions. Current soil wetness characterized by saturation, reduction, and

redoximorphic features.

Argillic horizon. A subsoil horizon characterized by an accumulation of illuvial clay.

Aspect. The direction toward which a slope faces. Also called slope aspect.

Association, soil. A group of soils or miscellaneous areas geographically associated

in a characteristic repeating pattern and defined and delineated as a single map

unit.

Available water capacity (available moisture capacity). The capacity of soils to

hold water available for use by most plants. It is commonly defined as the

difference between the amount of soil water at field moisture capacity and the

amount at wilting point. It is commonly expressed as inches of water per inch

of soil. The capacity, in inches, in a 60-inch profile or to a limiting layer is

expressed as:

Glossary
Supplement to the Soil Survey of Comanche County, Oklahoma

76

Very low .............................................................. 0 to 3

Low ...................................................................... 3 to 6

Moderate ............................................................. 6 to 9

High ................................................................... 9 to 12

Very high ................................................ more than 12

Backslope. The position that forms the steepest and generally linear, middle portion

of a hillslope. In profile, backslopes are commonly bounded by a convex shoulder

above and a concave footslope below.

Backswamp. A flood-plain landform. Extensive, marshy or swampy, depressed areas

of flood plains between natural levees and valley sides or terraces.

Badland. A landscape that is intricately dissected and characterized by a very fine

drainage network with high drainage densities and short, steep slopes and

narrow interfluves. Badlands develop on surfaces that have little or no vegetative

cover overlying unconsolidated or poorly cemented materials (clays, silts, or

sandstones) with, in some cases, soluble minerals, such as gypsum or halite.

Basal area. The area of a cross section of a tree, generally referring to the section at

breast height and measured outside the bark. It is a measure of stand density,

commonly expressed in square feet.

Base saturation. The degree to which material having cation-exchange properties is

saturated with exchangeable bases (sum of Ca, Mg, Na, and K), expressed as a

percentage of the total cation-exchange capacity.

Base slope (geomorphology). A geomorphic component of hills consisting of the

concave to linear (perpendicular to the contour) slope that, regardless of the

lateral shape, forms an apron or wedge at the bottom of a hillside dominated by

colluvium and slope-wash sediments (for example, slope alluvium).

Bedding plane. A planar or nearly planar bedding surface that visibly separates each

successive layer of stratified sediment or rock (of the same or different lithology)

from the preceding or following layer; a plane of deposition. It commonly marks a

change in the circumstances of deposition and may show a parting, a color

difference, a change in particle size, or various combinations of these. The term

is commonly applied to any bedding surface, even one that is conspicuously bent

or deformed by folding.

Bedrock. The solid rock that underlies the soil and other unconsolidated material or

that is exposed at the surface.

Bedrock-controlled topography. A landscape where the configuration and relief of

the landforms are determined or strongly influenced by the underlying bedrock.

Bisequum. Two sequences of soil horizons, each of which consists of an illuvial

horizon and the overlying eluvial horizons.

Blowout. A saucer-, cup-, or trough-shaped depression formed by wind erosion on a

preexisting dune or other sand deposit, especially in an area of shifting sand or

loose soil or where protective vegetation is disturbed or destroyed; the adjoining

accumulation of sand derived from the depression, where recognizable, is

commonly included. Blowouts are commonly small.

Bottom land. An informal term loosely applied to various portions of a flood plain.

Boulders. Rock fragments larger than 2 feet (60 centimeters) in diameter.

Breaks. A landscape or tract of steep, rough or broken land dissected by ravines and

gullies and marking a sudden change in topography.

Breast height. An average height of 4.5 feet above the ground surface; the point on

a tree where diameter measurements are ordinarily taken.

Brush management. Use of mechanical, chemical, or biological methods to make

conditions favorable for reseeding or to reduce or eliminate competition from

woody vegetation and thus allow understory grasses and forbs to recover. Brush

management increases forage production and thus reduces the hazard of

erosion. It can improve the habitat for some species of wildlife.
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Butte. An isolated, generally flat-topped hill or mountain with relatively steep slopes

and talus or precipitous cliffs and characterized by summit width that is less than

the height of bounding escarpments; commonly topped by a caprock of resistant

material and representing an erosion remnant carved from flat-lying rocks.

Calcareous soil. A soil containing enough calcium carbonate (commonly combined

with magnesium carbonate) to effervesce visibly when treated with cold, dilute

hydrochloric acid.

Caliche. A general term for a prominent zone of secondary carbonate accumulation

in surficial materials in warm, subhumid to arid areas. Caliche is formed by both

geologic and pedologic processes. Finely crystalline calcium carbonate forms a

nearly continuous surface-coating and void-filling medium in geologic (parent)

materials. Cementation ranges from weak in nonindurated forms to very strong in

indurated forms. Other minerals (e.g., carbonates, silicate, and sulfate) may

occur as accessory cements. Most petrocalcic horizons and some calcic horizons

are caliche.

Canopy. The leafy crown of trees or shrubs. (See Crown.)

Canyon. A long, deep, narrow valley with high, precipitous walls in an area of high

local relief.

Capillary water. Water held as a film around soil particles and in tiny spaces

between particles. Surface tension is the adhesive force that holds capillary water

in the soil.

Catena. A sequence, or “chain,” of soils on a landscape that formed in similar kinds of

parent material and under similar climatic conditions but that have different

characteristics as a result of differences in relief and drainage.

Cation. An ion carrying a positive charge of electricity. The common soil cations are

calcium, potassium, magnesium, sodium, and hydrogen.

Cation-exchange capacity. The total amount of exchangeable cations that can be

held by the soil, expressed in terms of milliequivalents per 100 grams of soil at

neutrality (pH 7.0) or at some other stated pH value. The term, as applied to soils,

is synonymous with base-exchange capacity but is more precise in meaning.

Catsteps. See Terracettes.

Channery soil material. Soil material that has, by volume, 15 to 35 percent thin, flat

fragments of sandstone, shale, slate, limestone, or schist as much as 6 inches

(15 centimeters) along the longest axis. A single piece is called a channer.

Chemical treatment. Control of unwanted vegetation through the use of chemicals.

Chiseling. Tillage with an implement having one or more soil-penetrating points that

shatter or loosen hard, compacted layers to a depth below normal plow depth.

Clay. As a soil separate, the mineral soil particles less than 0.002 millimeter in

diameter. As a soil textural class, soil material that is 40 percent or more clay,

less than 45 percent sand, and less than 40 percent silt.

Clay depletions. See Redoximorphic features.

Clay film. A thin coating of oriented clay on the surface of a soil aggregate or lining

pores or root channels. Synonyms: clay coating, clay skin.

Clay beds. Old, buried, alluvial clay sediments.

Claypan. A dense, compact, slowly permeable subsoil layer that contains much more

clay than the overlying materials, from which it is separated by a sharply defined

boundary. A claypan is commonly hard when dry and plastic and sticky when wet.

Climax plant community. The stabilized plant community on a particular site. The

plant cover reproduces itself and does not change so long as the environment

remains the same.

Coarse fragments. Mineral or rock particles larger than 2 millimeters in diameter.

Coarse textured soil. Sand or loamy sand.

Cobble (or cobblestone). A rounded or partly rounded fragment of rock 3 to 10

inches (7.6 to 25 centimeters) in diameter.
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Cobbly soil material. Material that has 15 to 35 percent, by volume, rounded or

partially rounded rock fragments 3 to 10 inches (7.6 to 25 centimeters) in

diameter. Very cobbly soil material has 35 to 60 percent of these rock fragments,

and extremely cobbly soil material has more than 60 percent.

COLE (coefficient of linear extensibility). See Linear extensibility.

Colluvium. Unconsolidated, unsorted earth material being transported or deposited

on side slopes and/or at the base of slopes by mass movement (e.g., direct

gravitational action) and by local, unconcentrated runoff.

Complex slope. Irregular or variable slope. Planning or establishing terraces,

diversions, and other water-control structures on a complex slope is difficult.

Complex, soil. A map unit of two or more kinds of soil or miscellaneous areas in

such an intricate pattern or so small in area that it is not practical to map them

separately at the selected scale of mapping. The pattern and proportion of the

soils or miscellaneous areas are somewhat similar in all areas.

Concretions. See Redoximorphic features.

Conglomerate. A coarse grained, clastic sedimentary rock composed of rounded or

subangular rock fragments more than 2 millimeters in diameter. It commonly has

a matrix of sand and finer textured material. Conglomerate is the consolidated

equivalent of gravel.

Conservation cropping system. Growing crops in combination with needed cultural

and management practices. In a good conservation cropping system, the soilimproving crops and practices more than offset the effects of the soil-depleting

crops and practices. Cropping systems are needed on all tilled soils. Soilimproving practices in a conservation cropping system include the use of

rotations that contain grasses and legumes and the return of crop residue to the

soil. Other practices include the use of green manure crops of grasses and

legumes, proper tillage, adequate fertilization, and weed and pest control.

Conservation tillage. A tillage system that does not invert the soil and that leaves a

protective amount of crop residue on the surface throughout the year.

Consistence, soil. Refers to the degree of cohesion and adhesion of soil material

and its resistance to deformation when ruptured. Consistence includes resistance

of soil material to rupture and to penetration; plasticity, toughness, and stickiness

of puddled soil material; and the manner in which the soil material behaves when

subject to compression. Terms describing consistence are defined in the “Soil

Survey Manual.”

Contour stripcropping. Growing crops in strips that follow the contour. Strips of

grass or close-growing crops are alternated with strips of clean-tilled crops or

summer fallow.

Control section. The part of the soil on which classification is based. The thickness

varies among different kinds of soil, but for many it is that part of the soil profile

between depths of 10 inches and 40 or 80 inches.

Coprogenous earth (sedimentary peat). A type of limnic layer composed

predominantly of fecal material derived from aquatic animals.

Corrosion (geomorphology). A process of erosion whereby rocks and soil are

removed or worn away by natural chemical processes, especially by the solvent

action of running water, but also by other reactions, such as hydrolysis, hydration,

carbonation, and oxidation.

Corrosion (soil survey interpretations). Soil-induced electrochemical or chemical

action that dissolves or weakens concrete or uncoated steel.

Cover crop. A close-growing crop grown primarily to improve and protect the soil

between periods of regular crop production, or a crop grown between trees and

vines in orchards and vineyards.

Crop residue management. Returning crop residue to the soil, which helps to maintain

soil structure, organic matter content, and fertility and helps to control erosion.
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79

Cropping system. Growing crops according to a planned system of rotation and

management practices.

Cross-slope farming. Deliberately conducting farming operations on sloping

farmland in such a way that tillage is across the general slope.

Crown. The upper part of a tree or shrub, including the living branches and their

foliage.

Cuesta. An asymmetric ridge capped by resistant rock layers of slight or moderate

dip (commonly less than 15 percent slopes); a type of homocline produced by

differential erosion of interbedded resistant and weak rocks. A cuesta has a long,

gentle slope on one side (dip slope) that roughly parallels the inclined beds; on

the other side, it has a relatively short and steep or clifflike slope (scarp) that cuts

through the tilted rocks.

Decreasers. The most heavily grazed climax range plants. Because they are the

most palatable, they are the first to be destroyed by overgrazing.

Deferred grazing. Postponing grazing or resting grazing land for a prescribed period.

Deflocculation. Dispersion, or breaking up , of soil aggregates into individual

particles. Sodium salts, for example, deflocculate, or disperse, granulated

particles of clay to form a clay that runs together, or puddles.

Depth, soil. Generally, the thickness of the soil over bedrock. Very deep soils are

more than 60 inches deep over bedrock; deep soils, 40 to 60 inches; moderately

deep, 20 to 40 inches; shallow, 10 to 20 inches; and very shallow, less than 10

inches.

Diatomaceous earth. A geologic deposit of fine, grayish siliceous material composed

chiefly or entirely of the remains of diatoms.

Dip slope. A slope of the land surface, roughly determined by and approximately

conforming to the dip of the underlying bedrock.

Diversion (or diversion terrace). A ridge of earth, generally a terrace, built to protect

downslope areas by diverting runoff from its natural course.

Drainage class (natural). Refers to the frequency and duration of wet periods under

conditions similar to those under which the soil formed. Alterations of the water

regime by human activities, either through drainage or irrigation, are not a

consideration unless they have significantly changed the morphology of the soil.

Seven classes of natural soil drainage are recognized—excessively drained,

somewhat excessively drained, well drained, moderately well drained, somewhat

poorly drained, poorly drained, and very poorly drained. These classes are

defined in the “Soil Survey Manual.”

Drainage, surface. Runoff, or surface flow of water, from an area.

Drainageway. A general term for a course or channel along which water moves in

draining an area. A term restricted to relatively small, linear depressions that at

some time move concentrated water and either do not have a defined channel or

have only a small defined channel.

Draw. A small stream valley that generally is shallower and more open than a ravine

or gulch and that has a broader bottom. The present stream channel may appear

inadequate to have cut the drainageway that it occupies.

Duff. A generally firm organic layer on the surface of mineral soils. It consists of fallen

plant material that is in the process of decomposition and includes everything

from the litter on the surface to underlying pure humus.

Dune. A low mound, ridge, bank, or hill of loose, windblown granular material

(generally sand), either barren and capable of movement from place to place or

covered and stabilized with vegetation but retaining its characteristic shape.

Earthy fill. See Mine spoil.

Ecological site. An area where climate, soil, and relief are sufficiently uniform to

produce a distinct natural plant community. An ecological site is the product of all

the environmental factors responsible for its development. It is typified by an
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association of species that differ from those on other ecological sites in kind

and/or proportion of species or in total production.

Eluviation. The movement of material in true solution or colloidal suspension from

one place to another within the soil. Soil horizons that have lost material through

eluviation are eluvial; those that have received material are illuvial.

Endosaturation. A type of saturation of the soil in which all horizons between the

upper boundary of saturation and a depth of 2 meters are saturated.

Eolian deposit. Sand-, silt-, or clay-sized clastic material transported and deposited

primarily by wind, commonly in the form of a dune or a sheet of sand or loess.

Ephemeral stream. A stream, or reach of a stream, that flows only in direct response

to precipitation. It receives no long-continued supply from melting snow or other

source, and its channel is above the water table at all times.

Episaturation. A type of saturation indicating a perched water table in a soil in which

saturated layers are underlain by one or more unsaturated layers within 2 meters

of the surface.

Erosion. The wearing away of the land surface by water, wind, ice, or other geologic

agents and by such processes as gravitational creep.

Erosion (geologic). Erosion caused by geologic processes acting over long

geologic periods and resulting in the wearing away of mountains and the

building up of such landscape features as flood plains and coastal plains.

Synonym: natural erosion.

Erosion (accelerated). Erosion much more rapid than geologic erosion, mainly as

a result of human or animal activities or of a catastrophe in nature, such as a

fire, that exposes the surface.

Erosion surface. A land surface shaped by the action of erosion, especially by

running water.

Escarpment. A relatively continuous and steep slope or cliff breaking the general

continuity of more gently sloping land surfaces and resulting from erosion or

faulting. Most commonly applied to cliffs produced by differential erosion.

Synonym: scarp.

Fallow. Cropland left idle in order to restore productivity through accumulation of

moisture. Summer fallow is common in regions of limited rainfall where cereal

grain is grown. The soil is tilled for at least one growing season for weed control

and decomposition of plant residue.

Fan remnant. A general term for landforms that are the remaining parts of older fan

landforms, such as alluvial fans, that have been either dissected or partially

buried.

Fertility, soil. The quality that enables a soil to provide plant nutrients, in adequate

amounts and in proper balance, for the growth of specified plants when light,

moisture, temperature, tilth, and other growth factors are favorable.

Field moisture capacity. The moisture content of a soil, expressed as a percentage

of the ovendry weight, after the gravitational, or free, water has drained away; the

field moisture content 2 or 3 days after a soaking rain; also called normal field

capacity, normal moisture capacity, or capillary capacity.

Fill slope. A sloping surface consisting of excavated soil material from a road cut. It

commonly is on the downhill side of the road.

Fine textured soil. Sandy clay, silty clay, or clay.

Firebreak. An area cleared of flammable material to stop or help control creeping or

running fires. It also serves as a line from which to work and to facilitate the

movement of firefighters and equipment. Designated roads also serve as

firebreaks.

First bottom. An obsolete, informal term loosely applied to the lowest flood-plain

steps that are subject to regular flooding.
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Flaggy soil material. Material that has, by volume, 15 to 35 percent flagstones. Very

flaggy soil material has 35 to 60 percent flagstones, and extremely flaggy soil

material has more than 60 percent flagstones.

Flagstone. A thin fragment of sandstone, limestone, slate, shale, or (rarely) schist 6

to 15 inches (15 to 38 centimeters) long.

Flood plain. The nearly level plain that borders a stream and is subject to flooding

unless protected artificially.

Flood-plain landforms. A variety of constructional and erosional features produced

by stream channel migration and flooding. Examples include backswamps, floodplain splays, meanders, meander belts, meander scrolls, oxbow lakes, and

natural levees.

Flood-plain splay. A fan-shaped deposit or other outspread deposit formed where an

overloaded stream breaks through a levee (natural or artificial) and deposits its

material (commonly coarse grained) on the flood plain.

Flood-plain step. An essentially flat, terrace-like alluvial surface within a valley that is

frequently covered by floodwater from the present stream; any approximately

horizontal surface still actively modified by fluvial scour and/or deposition. May

occur individually or as a series of steps.

Fluvial. Of or pertaining to rivers or streams; produced by stream or river action.

Foothills. A region of steeply sloping hills that fringes a mountain range or highplateau escarpment. The hills have relief of as much as 1,000 feet (300 meters).

Footslope. The concave surface at the base of a hillslope. A footslope is a transition

zone between upslope sites of erosion and transport (shoulders and backslopes)

and downslope sites of deposition (toeslopes).

Forb. Any herbaceous plant not a grass or a sedge.

Forest cover. All trees and other woody plants (underbrush) covering the ground in a

forest.

Forest type. A stand of trees similar in composition and development because of

given physical and biological factors by which it may be differentiated from other

stands.

Fragipan. A loamy, brittle subsurface horizon low in porosity and content of organic

matter and low or moderate in clay but high in silt or very fine sand. A fragipan

appears cemented and restricts roots. When dry, it is hard or very hard and has a

higher bulk density than the horizon or horizons above. When moist, it tends to

rupture suddenly under pressure rather than to deform slowly.

Genesis, soil. The mode of origin of the soil. Refers especially to the processes or

soil-forming factors responsible for the formation of the solum, or true soil, from

the unconsolidated parent material.

Gilgai. Commonly, a succession of microbasins and microknolls in nearly level areas

or of microvalleys and microridges parallel with the slope. Typically, the

microrelief of clayey soils that shrink and swell considerably with changes in

moisture content.

Gleyed soil. Soil that formed under poor drainage, resulting in the reduction of iron

and other elements in the profile and in gray colors.

Grassed waterway. A natural or constructed waterway, typically broad and shallow,

seeded to grass as protection against erosion. Conducts surface water away

from cropland.

Gravel. Rounded or angular fragments of rock as much as 3 inches (2 millimeters to

7.6 centimeters) in diameter. An individual piece is a pebble.

Gravelly soil material. Material that has 15 to 35 percent, by volume, rounded or

angular rock fragments, not prominently flattened, as much as 3 inches (7.6

centimeters) in diameter.

Green manure crop (agronomy). A soil-improving crop grown to be plowed under in

an early stage of maturity or soon after maturity.
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Ground water. Water filling all the unblocked pores of the material below the water

table.

Gully. A small channel with steep sides caused by erosion and cut in unconsolidated

materials by concentrated but intermittent flow of water. The distinction between a

gully and a rill is one of depth. A gully generally is an obstacle to farm machinery

and is too deep to be obliterated by ordinary tillage; a rill is of lesser depth and

can be smoothed over by ordinary tillage.

Hard bedrock. Bedrock that cannot be excavated except by blasting or by the use of

special equipment that is not commonly used in construction.

Hardpan. A hardened or cemented soil horizon, or layer. The soil material is sandy,

loamy, or clayey and is cemented by iron oxide, silica, calcium carbonate, or

other substance.

Head slope (geomorphology). A geomorphic component of hills consisting of a

laterally concave area of a hillside, especially at the head of a drainageway. The

overland waterflow is converging.

High-residue crops. Such crops as small grain and corn used for grain. If properly

managed, residue from these crops can be used to control erosion until the next

crop in the rotation is established. These crops return large amounts of organic

matter to the soil.

Hill. A generic term for an elevated area of the land surface, rising as much as 1,000

feet above surrounding lowlands, commonly of limited summit area and having a

well defined outline. Slopes are generally more than 15 percent. The distinction

between a hill and a mountain is arbitrary and may depend on local usage.

Hillslope. A generic term for the steeper part of a hill between its summit and the

drainage line, valley flat, or depression floor at the base of a hill.

Horizon, soil. A layer of soil, approximately parallel to the surface, having distinct

characteristics produced by soil-forming processes. In the identification of soil

horizons, an uppercase letter represents the major horizons. Numbers or

lowercase letters that follow represent subdivisions of the major horizons. An

explanation of the subdivisions is given in the “Soil Survey Manual.” The major

horizons of mineral soil are as follows:

O horizon.—An organic layer of fresh and decaying plant residue.

A horizon.—The mineral horizon at or near the surface in which an accumulation

of humified organic matter is mixed with the mineral material. Also, a plowed

surface horizon, most of which was originally part of a B horizon.

E horizon.—The mineral horizon in which the main feature is loss of silicate clay,

iron, aluminum, or some combination of these.

B horizon.—The mineral horizon below an A horizon. The B horizon is in part a

layer of transition from the overlying A to the underlying C horizon. The B

horizon also has distinctive characteristics, such as (1) accumulation of clay,

sesquioxides, humus, or a combination of these; (2) prismatic or blocky

structure; (3) redder or browner colors than those in the A horizon; or (4) a

combination of these.

C horizon.—The mineral horizon or layer, excluding indurated bedrock, that is

little affected by soil-forming processes and does not have the properties

typical of the overlying soil material. The material of a C horizon may be

either like or unlike that in which the solum formed. If the material is known

to differ from that in the solum, an Arabic numeral, commonly a 2, precedes

the letter C.

Cr horizon.—Soft, consolidated bedrock beneath the soil.

R layer.—Consolidated bedrock beneath the soil. The bedrock commonly

underlies a C horizon, but it can be directly below an A or a B horizon.

Humus. The well decomposed, more or less stable part of the organic matter in

mineral soils.
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Hydrologic soil groups. Refers to soils grouped according to their runoff potential.

The soil properties that influence this potential are those that affect the minimum

rate of water infiltration on a bare soil during periods after prolonged wetting

when the soil is not frozen. These properties are depth to a seasonal high water

table, the infiltration rate and permeability after prolonged wetting, and depth to a

very slowly permeable layer. The slope and the kind of plant cover are not

considered but are separate factors in predicting runoff.

Igneous rock. Rock that was formed by cooling and solidification of magma and that

has not been changed appreciably by weathering since its formation. Major

varieties include plutonic and volcanic rock (e.g., andesite, basalt, and granite).

Illuviation. The movement of soil material from one horizon to another in the soil

profile. Generally, material is removed from an upper horizon and deposited in a

lower horizon.

Impervious soil. A soil through which water, air, or roots penetrate slowly or not at

all. No soil is absolutely impervious to air and water all the time.

Increasers. Species in the climax vegetation that increase in amount as the more

desirable plants are reduced by close grazing. Increasers commonly are the

shorter plants and the less palatable to livestock.

Infiltration. The downward entry of water into the immediate surface of soil or other

material, as contrasted with percolation, which is movement of water through soil

layers or material.

Infiltration capacity. The maximum rate at which water can infiltrate into a soil under

a given set of conditions.

Infiltration rate. The rate at which water penetrates the surface of the soil at any

given instant, usually expressed in inches per hour. The rate can be limited by the

infiltration capacity of the soil or the rate at which water is applied at the surface.

Intake rate. The average rate of water entering the soil under irrigation. Most soils

have a fast initial rate; the rate decreases with application time. Therefore,

intake rate for design purposes is not a constant but is a variable depending

on the net irrigation application. The rate of water intake, in inches per hour, is

expressed as follows:

Less than 0.2 ................................................. very low

0.2 to 0.4 ................................................................ low

0.4 to 0.75 ........................................... moderately low

0.75 to 1.25 .................................................. moderate

1.25 to 1.75 ........................................ moderately high

1.75 to 2.5 ............................................................. high

More than 2.5 ................................................ very high

Interfluve. A landform composed of the relatively undissected upland or ridge

between two adjacent valleys containing streams flowing in the same general

direction. An elevated area between two drainageways that sheds water to those

drainageways.

Interfluve (geomorphology). A geomorphic component of hills consisting of the

uppermost, comparatively level or gently sloping area of a hill; shoulders of

backwearing hillslopes can narrow the upland or can merge, resulting in a

strongly convex shape.

Intermittent stream. A stream, or reach of a stream, that does not flow year-round

but that is commonly dry for 3 or more months out of 12 and whose channel is

generally below the local water table. It flows only during wet periods or when it

receives ground-water discharge or long, continued contributions from melting

snow or other surface and shallow subsurface sources.

Internal soil drainage. The downward movement of water through the soil profile.

The rate of movement is determined by the texture, structure, and other
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84

characteristics of the soil profile and underlying layers and by the height of the

water table, either permanent or perched. Relative terms for expressing internal

drainage are none, very slow, slow, medium, rapid, and very rapid.

Invaders. On range, plants that encroach into an area and grow after the climax

vegetation has been reduced by grazing. Generally, plants invade following

disturbance of the surface.

Iron depletions. See Redoximorphic features.

Irrigation. Application of water to soils to assist in production of crops. Methods of

irrigation are:

Basin.—Water is applied rapidly to nearly level plains surrounded by levees or

dikes.

Border.—Water is applied at the upper end of a strip in which the lateral flow of

water is controlled by small earth ridges called border dikes, or borders.

Controlled flooding.—Water is released at intervals from closely spaced field

ditches and distributed uniformly over the field.

Drip (or trickle).—Water is applied slowly and under low pressure to the surface

of the soil or into the soil through such applicators as emitters, porous tubing,

or perforated pipe.

Furrow.—Water is applied in small ditches made by cultivation implements.

Furrows are used for tree and row crops.

Sprinkler.—Water is sprayed over the soil surface through pipes or nozzles from

a pressure system.

Subirrigation.—Water is applied in open ditches or tile lines until the water table is

raised enough to wet the soil.

Karst (topography). A kind of topography that formed in limestone, gypsum, or other

soluble rocks by dissolution and that is characterized by closed depressions,

sinkholes, caves, and underground drainage.

Knoll. A small, low, rounded hill rising above adjacent landforms.

Ksat. Saturated hydraulic conductivity. (See Permeability.)

Lacustrine deposit. Material deposited in lake water and exposed when the water

level is lowered or the elevation of the land is raised.

Lake plain. A nearly level surface marking the floor of an extinct lake filled by well

sorted, generally fine textured, stratified deposits, commonly containing varves.

Lamellae. Thin bands of fibers of translocated clay that constitute illuvial, and in

many cases argillic, horizons in sandy upland soils.

Landslide. A general, encompassing term for most types of mass movement

landforms and processes involving the downslope transport and outward

deposition of soil and rock materials caused by gravitational forces; the

movement may or may not involve saturated materials. The speed and distance

of movement, as well as the amount of soil and rock material, vary greatly.

Leaching. The removal of soluble material from soil or other material by percolating

water.

Linear extensibility. Refers to the change in length of an unconfined clod as

moisture content is decreased from a moist to a dry state. Linear extensibility is

used to determine the shrink-swell potential of soils. It is an expression of the

volume change between the water content of the clod at 1

/3- or 1/10-bar tension

(33kPa or 10kPa tension) and oven dryness. Volume change is influenced by the

amount and type of clay minerals in the soil. The volume change is the percent

change for the whole soil. If it is expressed as a fraction, the resulting value is

COLE, coefficient of linear extensibility.

Liquid limit. The moisture content at which the soil passes from a plastic to a liquid

state.

Loam. Soil material that is 7 to 27 percent clay particles, 28 to 50 percent silt

particles, and less than 52 percent sand particles.
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85

Loess. Material transported and deposited by wind and consisting dominantly of siltsized particles.

Low strength. The soil is not strong enough to support loads.

Low-residue crops. Such crops as corn used for silage, peas, beans, and potatoes.

Residue from these crops is not adequate to control erosion until the next crop in

the rotation is established. These crops return little organic matter to the soil.

Map unit. Any soil, miscellaneous land type, soil complex, or undifferentiated soil

group shown on a detailed soil map and identified by a symbol.

Marl. An earthy, unconsolidated deposit consisting chiefly of calcium carbonate mixed

with clay in approximately equal proportions; formed primarily under freshwater

lacustrine conditions but also formed in more saline environments.

Mass movement. A generic term for the dislodgment and downslope transport of soil

and rock material as a unit under direct gravitational stress.

Masses. See Redoximorphic features.

Meander belt. The zone within which migration of a meandering channel occurs; the

flood-plain area included between two imaginary lines drawn tangential to the

outer bends of active channel loops.

Mechanical treatment. Use of mechanical equipment for seeding, brush

management, and other management practices.

Medium textured soil. Very fine sandy loam, loam, silt loam, or silt.

Mesa. A broad, nearly flat topped and commonly isolated landmass bounded by

steep slopes or precipitous cliffs and capped by layers of resistant, nearly

horizontal rocky material. The summit width is characteristically greater than the

height of the bounding escarpments.

Metamorphic rock. Rock of any origin altered in mineralogical composition, chemical

composition, or structure by heat, pressure, and movement at depth in the earth’s

crust. Nearly all such rocks are crystalline.

Mine spoil. An accumulation of displaced earthy material, rock, or other waste

material removed during mining or excavation. Also called earthy fill.

Mineral soil. Soil that is mainly mineral material and low in organic material. Its bulk

density is more than that of organic soil.

Minimum tillage. Only the tillage essential to crop production and prevention of soil

damage.

Miscellaneous area. A kind of map unit that has little or no natural soil and supports

little or no vegetation.

Miscellaneous land type. A map unit consisting of areas of land that have little or no

natural soil, that are too nearly inaccessible for orderly examination, or that occur

where, for other reasons, it is not feasible to classify the soil.

Moderately coarse textured soil. Coarse sandy loam, sandy loam, or fine sandy

loam.

Moderately fine textured soil. Clay loam, sandy clay loam, or silty clay loam.

Mollic epipedon. A thick, dark, humus-rich surface horizon (or horizons) that has

high base saturation and pedogenic soil structure. It may include the upper part

of the subsoil.

Morphology, soil. The physical makeup of the soil, including the texture, structure,

porosity, consistence, color, and other physical, mineral, and biological properties

of the various horizons, and the thickness and arrangement of those horizons in

the soil profile.

Mottling, soil. Irregular spots of different colors that vary in number and size.

Descriptive terms are as follows: abundance—few, common, and many; size—

fine, medium, and coarse; and contrast—faint, distinct, and prominent. The size

measurements are of the diameter along the greatest dimension. Fine indicates

less than 5 millimeters (about 0.2 inch); medium, from 5 to 15 millimeters (about

0.2 to 0.6 inch); and coarse, more than 15 millimeters (about 0.6 inch).
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Mountain. A generic term for an elevated area of the land surface, rising more than

1,000 feet (300 meters) above surrounding lowlands, commonly of restricted

summit area (relative to a plateau) and generally having steep sides. A mountain

can occur as a single, isolated mass or in a group forming a chain or range.

Mountains are formed primarily by tectonic activity and/or volcanic action but can

also be formed by differential erosion.

Mudstone. A blocky or massive, fine grained sedimentary rock in which the

proportions of clay and silt are approximately equal. Also, a general term for such

material as clay, silt, claystone, siltstone, shale, and argillite and that should be

used only when the amounts of clay and silt are not known or cannot be precisely

identified.

Munsell notation. A designation of color by degrees of three simple variables—hue,

value, and chroma. For example, a notation of 10YR 6/4 is a color with hue of

10YR, value of 6, and chroma of 4.

Natric horizon. A special kind of argillic horizon that contains enough exchangeable

sodium to have an adverse effect on the physical condition of the subsoil.

Natural drainage. Refers to conditions that existed during the development of a soil,

as opposed to altered drainage, which is commonly the result of artificial drainage

or irrigation but may be caused by the sudden deepening of channels or the

blocking of drainage outlets. Seven different classes of natural drainage are

recognized.

Neutral soil. A soil having a pH value of 6.6 to 7.3. (See Reaction, soil.)

Nodules. See Redoximorphic features.

Nose slope (geomorphology). A geomorphic component of hills consisting of the

projecting end (laterally convex area) of a hillside. The overland waterflow is

predominantly divergent. Nose slopes consist dominantly of colluvium and slopewash sediments (for example, slope alluvium).

Nutrient, plant. Any element taken in by a plant essential to its growth. Plant

nutrients are mainly nitrogen, phosphorus, potassium, calcium, magnesium,

sulfur, iron, manganese, copper, boron, and zinc obtained from the soil and

carbon, hydrogen, and oxygen obtained from the air and water.

Open space. A relatively undeveloped green or wooded area provided mainly within

an urban area to minimize feelings of congested living.

Organic matter. Plant and animal residue in the soil in various stages of

decomposition. The content of organic matter in the surface layer is described

as follows:

Very low .....................................less than 0.5 percent

Low .................................................. 0.5 to 1.0 percent

Moderately low ................................ 1.0 to 2.0 percent

Moderate ......................................... 2.0 to 4.0 percent

High ................................................. 4.0 to 8.0 percent

Very high .................................. more than 8.0 percent

Paleoterrace. An erosional remnant of a terrace that retains the surface form and

alluvial deposits of its origin but was not emplaced by, and commonly does not

grade to, a present-day stream or drainage network.

Pan. A compact, dense layer in a soil that impedes the movement of water and the

growth of roots. For example, hardpan, fragipan, claypan, plowpan, and traffic pan.

Parent material. The unconsolidated organic and mineral material in which soil

forms.

Ped. An individual natural soil aggregate, such as a granule, a prism, or a block.

Pedisediment. A layer of sediment, eroded from the shoulder and backslope of an

erosional slope, that lies on and is being (or was) transported across a gently

sloping erosional surface at the foot of a receding hill or mountain slope.
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Pedon. The smallest volume that can be called “a soil.” A pedon is three dimensional

and large enough to permit study of all horizons. Its area ranges from about 10 to

100 square feet (1 square meter to 10 square meters), depending on the

variability of the soil.

Percolation. The movement of water through the soil.

Permeability. The quality of the soil that enables water or air to move downward

through the profile. The rate at which a saturated soil transmits water is

accepted as a measure of this quality. In soil physics, the rate is referred to as

“saturated hydraulic conductivity,” which is defined in the “Soil Survey

Manual.” In line with conventional usage in the engineering profession and

with traditional usage in published soil surveys, this rate of flow continues to

be expressed as “permeability.” Terms describing permeability, measured in

inches per hour, are as follows:

Impermeable ............................. less than 0.0015 inch

Very slow ...................................... 0.0015 to 0.06 inch

Slow .................................................... 0.06 to 0.2 inch

Moderately slow .................................... 0.2 to 0.6 inch

Moderate ................................... 0.6 inch to 2.0 inches

Moderately rapid ............................... 2.0 to 6.0 inches

Rapid .................................................. 6.0 to 20 inches

Very rapid ................................... more than 20 inches

pH value. A numerical designation of acidity and alkalinity in soil. (See Reaction, soil.)

Phase, soil. A subdivision of a soil series based on features that affect its use and

management, such as slope, stoniness, and flooding.

Plastic limit. The moisture content at which a soil changes from semisolid to plastic.

Plasticity index. The numerical difference between the liquid limit and the plastic

limit; the range of moisture content within which the soil remains plastic.

Plateau (geomorphology). A comparatively flat area of great extent and elevation;

specifically, an extensive land region that is considerably elevated (more than

100 meters) above the adjacent lower lying terrain, is commonly limited on at

least one side by an abrupt descent, and has a flat or nearly level surface. A

comparatively large part of a plateau surface is near summit level.

Playa. The generally dry and nearly level lake plain that occupies the lowest parts of

closed depressions, such as those on intermontane basin floors. Temporary

flooding occurs primarily in response to precipitation and runoff. Playa deposits

are fine grained and may or may not have a high water table and saline

conditions.

Plinthite. The sesquioxide-rich, humus-poor, highly weathered mixture of clay with

quartz and other diluents. It commonly appears as red mottles, usually in platy,

polygonal, or reticulate patterns. Plinthite changes irreversibly to an ironstone

hardpan or to irregular aggregates on repeated wetting and drying, especially if it

is exposed also to heat from the sun. In a moist soil, plinthite can be cut with a

spade. It is a form of laterite.

Plowpan. A compacted layer formed in the soil directly below the plowed layer.

Ponding. Standing water on soils in closed depressions. Unless the soils are

artificially drained, the water can be removed only by percolation or

evapotranspiration.

Poorly graded. Refers to a coarse grained soil or soil material consisting mainly of

particles of nearly the same size. Because there is little difference in size of the

particles, density can be increased only slightly by compaction.

Pore linings. See Redoximorphic features.

Potential native plant community. See Climax plant community.
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Potential rooting depth (effective rooting depth). Depth to which roots could

penetrate if the content of moisture in the soil were adequate. The soil has no

properties restricting the penetration of roots to this depth.

Prescribed burning. Deliberately burning an area for specific management

purposes, under the appropriate conditions of weather and soil moisture and at

the proper time of day.

Productivity, soil. The capability of a soil for producing a specified plant or sequence

of plants under specific management.

Profile, soil. A vertical section of the soil extending through all its horizons and into

the parent material.

Proper grazing use. Grazing at an intensity that maintains enough cover to protect

the soil and maintain or improve the quantity and quality of the desirable

vegetation. This practice increases the vigor and reproduction capacity of the key

plants and promotes the accumulation of litter and mulch necessary to conserve

soil and water.

Rangeland. Land on which the potential natural vegetation is predominantly grasses,

grasslike plants, forbs, or shrubs suitable for grazing or browsing. It includes

natural grasslands, savannas, many wetlands, some deserts, tundras, and areas

that support certain forb and shrub communities.

Reaction, soil. A measure of acidity or alkalinity of a soil, expressed as pH values. A

soil that tests to pH 7.0 is described as precisely neutral in reaction because it is

neither acid nor alkaline. The degrees of acidity or alkalinity, expressed as pH

values, are:

Ultra acid ................................................. less than 3.5

Extremely acid ..............................................3.5 to 4.4

Very strongly acid .........................................4.5 to 5.0

Strongly acid .................................................5.1 to 5.5

Moderately acid ............................................5.6 to 6.0

Slightly acid ...................................................6.1 to 6.5

Neutral ..........................................................6.6 to 7.3

Slightly alkaline .............................................7.4 to 7.8

Moderately alkaline ......................................7.9 to 8.4

Strongly alkaline ...........................................8.5 to 9.0

Very strongly alkaline .......................... 9.1 and higher

Red beds. Sedimentary strata that are mainly red and are made up largely of

sandstone and shale.

Redoximorphic concentrations. See Redoximorphic features.

Redoximorphic depletions. See Redoximorphic features.

Redoximorphic features. Redoximorphic features are associated with wetness and

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. 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

redoximorphic processes in a soil may result in redoximorphic features that are

defined as follows:

1. Redoximorphic concentrations.—These are zones of apparent accumulation of

iron-manganese oxides, including:

A. Nodules and concretions, which are cemented bodies that can be

removed from the soil intact. Concretions are distinguished from nodules on
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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; and

B. Masses, which are noncemented concentrations of substances within the

soil matrix; and

C. 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.

2. Redoximorphic depletions.—These are zones of low chroma (chromas less

than those in the matrix) where either iron-manganese oxides alone or both

iron-manganese oxides and clay have been stripped out, including:

A. Iron depletions, i.e., zones that contain low amounts of iron and

manganese oxides but have a clay content similar to that of the adjacent

matrix; and

B. Clay depletions, i.e., zones that contain low amounts of iron, manganese,

and clay (often referred to as silt coatings or skeletans).

3. 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.

Reduced matrix. See Redoximorphic features.

Regolith. All unconsolidated earth materials above the solid bedrock. It includes

material weathered in place from all kinds of bedrock and alluvial, glacial, eolian,

lacustrine, and pyroclastic deposits.

Relief. The relative difference in elevation between the upland summits and the

lowlands or valleys of a given region.

Residuum (residual soil material). Unconsolidated, weathered or partly weathered

mineral material that accumulated as bedrock disintegrated in place.

Rill. A very small, steep-sided channel resulting from erosion and cut in

unconsolidated materials by concentrated but intermittent flow of water. A rill

generally is not an obstacle to wheeled vehicles and is shallow enough to be

smoothed over by ordinary tillage.

Rippable. Rippable bedrock or hardpan can be excavated using a single-tooth

ripping attachment mounted on a tractor with a 200–300 drawbar horsepower

rating.

Riser. The vertical or steep side slope (e.g., escarpment) of terraces, flood-plain

steps, or other stepped landforms; commonly a recurring part of a series of

natural, steplike landforms, such as successive stream terraces.

Road cut. A sloping surface produced by mechanical means during road

construction. It is commonly on the uphill side of the road.

Rock fragments. Rock or mineral fragments having a diameter of 2 millimeters or

more; for example, pebbles, cobbles, stones, and boulders.

Root zone. The part of the soil that can be penetrated by plant roots.

Runoff. The precipitation discharged into stream channels from an area. The water

that flows off the surface of the land without sinking into the soil is called surface

runoff. Water that enters the soil before reaching surface streams is called

ground-water runoff or seepage flow from ground water.

Saline soil. A soil containing soluble salts in an amount that impairs growth of plants.

A saline soil does not contain excess exchangeable sodium.

Sand. As a soil separate, individual rock or mineral fragments from 0.05 millimeter

to 2.0 millimeters in diameter. Most sand grains consist of quartz. As a soil

textural class, a soil that is 85 percent or more sand and not more than 10

percent clay.

Sandstone. Sedimentary rock containing dominantly sand-sized particles.

Saturated hydraulic conductivity (Ksat). See Permeability.
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Saturation. Wetness characterized by zero or positive pressure of the soil water.

Under conditions of saturation, the water will flow from the soil matrix into an

unlined auger hole.

Scarification. The act of abrading, scratching, loosening, crushing, or modifying the

surface to increase water absorption or to provide a more tillable soil.

Sedimentary rock. A consolidated deposit of clastic particles, chemical precipitates,

or organic remains accumulated at or near the surface of the earth under normal

low temperature and pressure conditions. Sedimentary rocks include

consolidated equivalents of alluvium, colluvium, drift, and eolian, lacustrine, and

marine deposits. Examples are sandstone, siltstone, mudstone, claystone, shale,

conglomerate, limestone, dolomite, and coal.

Sequum. A sequence consisting of an illuvial horizon and the overlying eluvial

horizon. (See Eluviation.)

Series, soil. A group of soils that have profiles that are almost alike, except for

differences in texture of the surface layer. All the soils of a series have horizons

that are similar in composition, thickness, and arrangement.

Shale. Sedimentary rock that formed by the hardening of a deposit of clay, silty clay,

or silty clay loam and that has a tendency to split into thin layers.

Sheet erosion. The removal of a fairly uniform layer of soil material from the land

surface by the action of rainfall and surface runoff.

Shoulder. The convex, erosional surface near the top of a hillslope. A shoulder is a

transition from summit to backslope.

Shrub-coppice dune. A small, streamlined dune that forms around brush and clump

vegetation.

Side slope (geomorphology). A geomorphic component of hills consisting of a

laterally planar area of a hillside. The overland waterflow is predominantly

parallel. Side slopes are dominantly colluvium and slope-wash sediments.

Silica. A combination of silicon and oxygen. The mineral form is called quartz.

Silica-sesquioxide ratio. The ratio of the number of molecules of silica to the

number of molecules of alumina and iron oxide. The more highly weathered soils

or their clay fractions in warm-temperate, humid regions, and especially those in

the tropics, generally have a low ratio.

Silt. As a soil separate, individual mineral particles that range in diameter from the

upper limit of clay (0.002 millimeter) to the lower limit of very fine sand (0.05

millimeter). As a soil textural class, soil that is 80 percent or more silt and less

than 12 percent clay.

Siltstone. An indurated silt having the texture and composition of shale but lacking its

fine lamination or fissility; a massive mudstone in which silt predominates over clay.

Similar soils. Soils that share limits of diagnostic criteria, behave and perform in a

similar manner, and have similar conservation needs or management

requirements for the major land uses in the survey area.

Sinkhole. A closed, circular or elliptical depression, commonly funnel shaped,

characterized by subsurface drainage and formed either by dissolution of the

surface of underlying bedrock (e.g., limestone, gypsum, or salt) or by collapse of

underlying caves within bedrock. Complexes of sinkholes in carbonate-rock

terrain are the main components of karst topography.

Similarity index. The present composition of the plant community on an ecological

site in relation to the potential natural plant community for that site. Similarity

index is expressed as excellent, good, fair, or poor, on the basis of how much the

present plant community has departed from the potential.

Site index. A designation of the quality of a forest site based on the height of the

dominant stand at an arbitrarily chosen age. For example, if the average height

attained by dominant and codominant trees in a fully stocked stand at the age of

50 years is 75 feet, the site index is 75.
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Slickensides (pedogenic). Grooved, striated, and/or glossy (shiny) slip faces on

structural peds, such as wedges; produced by shrink-swell processes, most

commonly in soils that have a high content of expansive clays.

Slope. The inclination of the land surface from the horizontal. Percentage of slope is

the vertical distance divided by horizontal distance, then multiplied by 100. Thus,

a slope of 20 percent is a drop of 20 feet in 100 feet of horizontal distance. In this

survey, classes for simple slopes are as follows:

Nearly level ........................................... 0 to 1 percent

Very gently sloping ............................... 1 to 3 percent

Gently sloping ....................................... 3 to 5 percent

Moderately sloping ............................... 5 to 8 percent

Strongly sloping .................................. 8 to 12 percent

Moderately steep .............................. 12 to 20 percent

Steep ................................................. 20 to 45 percent

Very steep ................................ 45 percent and higher

Classes for complex slopes are as follows:

Nearly level ........................................... 0 to 3 percent

Gently undulating.................................. 1 to 5 percent

Undulating ............................................. 1 to 8 percent

Gently rolling ....................................... 5 to 12 percent

Rolling ................................................. 5 to 15 percent

Hilly ..................................................... 8 to 30 percent

Steep ................................................. 20 to 45 percent

Very steep ................................ 45 percent and higher

Slope alluvium. Sediment gradually transported down the slopes of mountains or

hills primarily by nonchannel alluvial processes (i.e., slope-wash processes) and

characterized by particle sorting. Lateral particle sorting is evident on long slopes.

In a profile sequence, sediments may be distinguished by differences in size

and/or specific gravity of rock fragments and may be separated by stone lines.

Burnished peds and sorting of rounded or subrounded pebbles or cobbles

distinguish these materials from unsorted colluvial deposits.

Sodic (alkali) soil. A soil having so high a degree of alkalinity (pH 8.5 or higher) or so

high a percentage of exchangeable sodium (15 percent or more of the total

exchangeable bases), or both, that plant growth is restricted.

Sodicity. The degree to which a soil is affected by exchangeable sodium. Sodicity is

expressed as a sodium adsorption ratio (SAR) of a saturation extract, or the ratio

of Na+ to Ca++ + Mg++. The degrees of sodicity and their respective ratios are:

Slight ..................................................... less than 13:1

Moderate ......................................................... 13-30:1

Strong .................................................. more than 30:1

Sodium adsorption ratio (SAR). A measure of the amount of sodium (Na) relative to

calcium (Ca) and magnesium (Mg) in the water extract from saturated soil paste.

It is the ratio of the Na concentration divided by the square root of one-half of the

Ca + Mg concentration.

Soft bedrock. Bedrock that can be excavated with trenching machines, backhoes,

small rippers, and other equipment commonly used in construction.

Soil. A natural, three-dimensional body at the earth’s surface. It is capable of

supporting plants and has properties resulting from the integrated effect of

climate and living matter acting on earthy parent material, as conditioned by relief

and by the passage of time.
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92

Soil separates. Mineral particles less than 2 millimeters in equivalent diameter and

ranging between specified size limits. The names and sizes, in millimeters, of

separates recognized in the United States are as follows:

Very coarse sand ..........................................2.0 to 1.0

Coarse sand .................................................1.0 to 0.5

Medium sand ............................................. 0.5 to 0.25

Fine sand ................................................. 0.25 to 0.10

Very fine sand .......................................... 0.10 to 0.05

Silt .......................................................... 0.05 to 0.002

Clay ..................................................... less than 0.002

Solum. The upper part of a soil profile, above the C horizon, in which the processes

of soil formation are active. The solum in soil consists of the A, E, and B horizons.

Generally, the characteristics of the material in these horizons are unlike those of

the material below the solum. The living roots and plant and animal activities are

largely confined to the solum.

Stone line. In a vertical cross section, a line formed by scattered fragments or a

discrete layer of angular and subangular rock fragments (commonly a gravel- or

cobble-sized lag concentration) that formerly was draped across a topographic

surface and was later buried by additional sediments. A stone line generally caps

material that was subject to weathering, soil formation, and erosion before burial.

Many stone lines seem to be buried erosion pavements, originally formed by

sheet and rill erosion across the land surface.

Stones. Rock fragments 10 to 24 inches (25 to 60 centimeters) in diameter if

rounded or 15 to 24 inches (38 to 60 centimeters) in length if flat.

Stony. Refers to a soil containing stones in numbers that interfere with or prevent

tillage.

Strath terrace. A type of stream terrace; formed as an erosional surface cut on

bedrock and thinly mantled with stream deposits (alluvium).

Stream terrace. One of a series of platforms in a stream valley, flanking and more or

less parallel to the stream channel, originally formed near the level of the stream;

represents the remnants of an abandoned flood plain, stream bed, or valley floor

produced during a former state of fluvial erosion or deposition.

Stripcropping. Growing crops in a systematic arrangement of strips or bands that

provide vegetative barriers to wind erosion and water erosion.

Structure, soil. The arrangement of primary soil particles into compound particles or

aggregates. The principal forms of soil structure are—platy (laminated), prismatic

(vertical axis of aggregates longer than horizontal), columnar (prisms with

rounded tops), blocky (angular or subangular), and granular. Structureless soils

are either single grained (each grain by itself, as in dune sand) or massive (the

particles adhering without any regular cleavage, as in many hardpans).

Stubble mulch. Stubble or other crop residue left on the soil or partly worked into the

soil. It protects the soil from wind erosion and water erosion after harvest, during

preparation of a seedbed for the next crop, and during the early growing period of

the new crop.

Subsoil. Technically, the B horizon; roughly, the part of the solum below plow depth.

Subsoiling. Tilling a soil below normal plow depth, ordinarily to shatter a hardpan or

claypan.

Substratum. The part of the soil below the solum.

Subsurface layer. Any surface soil horizon (A, E, AB, or EB) below the surface layer.

Summer fallow. The tillage of uncropped land during the summer to control weeds

and allow storage of moisture in the soil for the growth of a later crop. A practice

common in semiarid regions, where annual precipitation is not enough to produce
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93

a crop every year. Summer fallow is frequently practiced before planting winter

grain.

Summit. The topographically highest position of a hillslope. It has a nearly level

(planar or only slightly convex) surface.

Surface layer. The soil ordinarily moved in tillage, or its equivalent in uncultivated

soil, ranging in depth from 4 to 10 inches (10 to 25 centimeters). Frequently

designated as the “plow layer,” or the “Ap horizon.”

Surface soil. The A, E, AB, and EB horizons, considered collectively. It includes all

subdivisions of these horizons.

Talf. A geomorphic component of flat plains (e.g., lake plains, low coastal plains, lowgradient till plains) consisting of an essentially flat (0 or 1 percent slopes), broad

area dominated by closed depressions and a nonintegrated or poorly integrated

drainage system. Precipitation tends to pond locally, and lateral transport is slow

both above and below ground, favoring the accumulation of organic matter and

the retention of fine-earth sediments. Better drained soils are commonly adjacent

to drainageways.

Talus. Rock fragments of any size or shape (commonly coarse and angular) derived

from and lying at the base of a cliff or very steep rock slope. The accumulated

mass of such loose broken rock formed chiefly by falling, rolling, or sliding.

Taxadjuncts. Soils that cannot be classified in a series recognized in the

classification system. Such soils are named for a series they strongly resemble

and are designated as taxadjuncts to that series because they differ in ways too

small to be of consequence in interpreting their use and behavior. Soils are

recognized as taxadjuncts only when one or more of their characteristics are

slightly outside the range defined for the family of the series for which the soils

are named.

Terrace (conservation). An embankment, or ridge, constructed across sloping soils

on the contour or at a slight angle to the contour. The terrace intercepts surface

runoff so that water soaks into the soil or flows slowly to a prepared outlet. A

terrace in a field generally is built so that the field can be farmed. A terrace

intended mainly for drainage has a deep channel that is maintained in permanent

sod.

Terrace (geomorphology). A steplike surface, bordering a valley floor or shoreline,

that represents the former position of a flood plain, lake, or seashore. The term is

usually applied both to the relatively flat summit surface (tread) that was cut or

built by stream or wave action and to the steeper descending slope (scarp or

riser) that has graded to a lower base level of erosion.

Terracettes. Small, irregular steplike forms on steep hillslopes, especially in pasture,

formed by creep or erosion of surficial materials that may be induced or

enhanced by trampling of livestock, such as sheep or cattle.

Texture, soil. The relative proportions of sand, silt, and clay particles in a mass of

soil. The basic textural classes, in order of increasing proportion of fine particles,

are sand, loamy sand, sandy loam, loam, silt loam, silt, sandy clay loam, clay

loam, silty clay loam, sandy clay, silty clay, and clay. The sand, loamy sand, and

sandy loam classes may be further divided by specifying “coarse,” “fine,” or “very

fine.”

Tilth, soil. The physical condition of the soil as related to tillage, seedbed

preparation, seedling emergence, and root penetration.

Toeslope. The gently inclined surface at the base of a hillslope. Toeslopes in profile

are commonly gentle and linear and are constructional surfaces forming the lower

part of a hillslope continuum that grades to valley or closed-depression floors.

Topsoil. The upper part of the soil, which is the most favorable material for plant

growth. It is ordinarily rich in organic matter and is used to topdress roadbanks,

lawns, and land affected by mining.
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Trace elements. Chemical elements, for example, zinc, cobalt, manganese, copper,

and iron, in soils in extremely small amounts. They are essential to plant growth.

Tread. The flat to gently sloping, topmost, laterally extensive slope of terraces, floodplain steps, or other stepped landforms; commonly a recurring part of a series of

natural steplike landforms, such as successive stream terraces.

Upland. An informal, general term for the higher ground of a region, in contrast with a

low-lying adjacent area, such as a valley or plain, or for land at a higher elevation

than the flood plain or low stream terrace; land above the footslope zone of the

hillslope continuum.

Valley fill. The unconsolidated sediment deposited by any agent (water, wind, ice, or

mass wasting) so as to fill or partly fill a valley.

Variant, soil. A soil having properties sufficiently different from those of other known

soils to justify a new series name, but occurring in such a limited geographic area

that creation of a new series is not justified.

Variegation. Refers to patterns of contrasting colors assumed to be inherited from

the parent material rather than to be the result of poor drainage.

Water-holding capacity. See Available water capacity.

Weathering. All physical disintegration, chemical decomposition, and biologically

induced changes in rocks or other deposits at or near the earth’s surface by

atmospheric or biologic agents or by circulating surface waters but involving

essentially no transport of the altered material.

Well graded. Refers to soil material consisting of coarse grained particles that are

well distributed over a wide range in size or diameter. Such soil normally can be

easily increased in density and bearing properties by compaction. Contrasts with

poorly graded soil.

Wilting point (or permanent wilting point). The moisture content of soil, on an

ovendry basis, at which a plant (specifically a sunflower) wilts so much that it

does not recover when placed in a humid, dark chamber.

Windthrow. The uprooting and tipping over of trees by the wind.

Winnowing. The removal of clay and silt particles from the soil by strong winds. The

coarser particles remain, and the soil becomes sandier and more highly erodible

as the process continues.
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