ICP Forest Manual 2016 Sampling & Analysis of Soils
Source: environment.data.gov.uk (2026-01-05)

NFI+ Soil Condition & Health. This dataset contains comprehensive soil chemical and physical indicators collected as part of the NFI+ (National Forest Inventory Plus) programme and the BioSoil forest soil and biodiversity monitoring network. The dataset covers forest soil sampling sites across Great Britain and provides baseline and monitoring data on soil condition and health in forest ecosystems.

Chemical indicators measured include: soil pH (measured in water and CaCl2), organic carbon content (%), total nitrogen (%), available phosphorus (mg/kg), exchangeable cations (Ca, Mg, K, Na in cmol/kg), cation exchange capacity (cmol/kg), base saturation (%), and heavy metal concentrations where applicable.

Physical indicators measured include: soil texture (% sand, silt, clay), bulk density (g/cm³), porosity (%), aggregate stability, moisture content at sampling, and soil depth profiles.

Samples were collected at multiple depth intervals (0-10cm, 10-20cm, 20-40cm) using standardised protocols aligned with ICP Forests and BioSoil methodologies.  Each sampling location includes associated metadata on forest type, soil type, elevation and forest origin (plantation or natural).  The data include chemical and physical soil properties.

Quality assurance procedures included duplicate sampling, laboratory reference standards, and inter-laboratory comparisons.

Limitations:  Data coverage is limited to forest soils only. Some historical samples may have incomplete heavy metal analysis. Seasonal variation should be considered when interpreting results.

Data are georeferenced using a delocalised grid. The bounding coordinates for each grid square are included in the dataset. Further information about the delocalisation process is provided in the dataset evidence pack.

The 'NFI+ Soil Condition & Health' is a project funded by the UK Government through Defra’s Natural Capital and Ecosystem Assessment programme (NCEA), England sites, and the Department for Energy, Security and Net Zero (DESNZ), Scotland sites.  Users should ensure they have read the supporting documentation before viewing or making use of the data. This includes the NCEA Analysis Ready Data Limitations Statement and dataset specific limitations/caveats outlined in the supporting documentation, please refer to the 'Metadata' tab on the 'Soil Condition Data 2022-24' dataset  Attribution statement: © Forestry Commission copyright and/or database right 2025. Includes data from Ordnance Survey, British Geological Survey, and the Met Office. All rights reserved.

United Nations Economic Commission for Europe (UNECE)
Convention on Long-range Transboundary Air Pollution (CLRTAP)
International Co-operative Programme on Assessment and
Monitoring of Air Pollution Effects on Forests (ICP Forests)
ANNEX II–VII TO MANUAL
on
methods and criteria for harmonized sampling, assessment,
monitoring and analysis of the effects of air pollution on forests
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CONTENTS

ANNEX II
– GUIDELINES FOR FOREST SOIL DESCRIPTION ................................................................. 105
0
INTRODUCTION ................................................................................................................................... 105
1
GENERAL SITE INFORMATION ............................................................................................................ 105
1.1
OBSERVATION PLOT NUMBER ............................................................................................................................................................ 105
1.2
PROFILE ID .................................................................................................................................................................................................. 105
1.3
DATE OF PROFILE DESCRIPTION ........................................................................................................................................................ 105
1.4
PROFILE LATITUDE-/ LONGITUDE COORDINATES ....................................................................................................................... 106
1.5
ELEVATION ................................................................................................................................................................................................. 106
2
SOIL FORMING FACTORS .................................................................................................................... 106
2.1
CLIMATE AND WEATHER CONDITIONS ............................................................................................................................................ 106
2.2
SOIL CLIMATE ............................................................................................................................................................................................ 107
2.3
TOPOGRAPHY ........................................................................................................................................................................................... 108
2.4
LAND USE ................................................................................................................................................................................................... 110
2.5
HUMAN INFLUENCE ................................................................................................................................................................................ 110
2.6
VEGETATION .............................................................................................................................................................................................. 111
2.7
PARENT MATERIAL .................................................................................................................................................................................. 111
2.8
NATURAL DRAINAGE CLASSES ........................................................................................................................................................... 111
2.9
WATER AVAILABILITY ............................................................................................................................................................................. 113
2.10
PERIOD OF WATER SATURATION ................................................................................................................................................. 113
2.11
EXTERNAL DRAINAGE ...................................................................................................................................................................... 113
2.12
FLOODING ............................................................................................................................................................................................ 114
2.13
GROUNDWATER TABLE ................................................................................................................................................................... 114
2.14
ROCK OUTCROPS ............................................................................................................................................................................... 115
2.15
COARSE SURFACE FRAGMENTS ................................................................................................................................................... 116
2.16
EROSION AND SEDIMENTATION .................................................................................................................................................. 116
2.17
SURFACE SEALING ............................................................................................................................................................................ 118
2.18
SURFACE CRACKS .............................................................................................................................................................................. 118
2.19
SALT ........................................................................................................................................................................................................ 119
2.20
PROFILE DEPTH .................................................................................................................................................................................. 119
3
SOIL HORIZON DESCRIPTION ............................................................................................................. 120
3.1
HORIZON BOUNDARY (MODIFIED FROM FAO, 2006) ................................................................................................................. 121
3.2
PHOTOGRAPHIC RECORDINGS ........................................................................................................................................................... 122
3.3
SOIL COLOUR ............................................................................................................................................................................................ 123
3.4
MOTTLING .................................................................................................................................................................................................. 123
3.5
REDOXIMORPHIC PROPERTIES (IUSS WORKING GROUP WRB, 2015) .................................................................................... 125
3.6
TEXTURE OF THE FINE-EARTH FRACTION ....................................................................................................................................... 127
3.7
ROCK FRAGMENTS .................................................................................................................................................................................. 129
3.8
ANDIC MATERIAL ..................................................................................................................................................................................... 130
3.9
SOIL STRUCTURE (MODIFIED FROM FAO, 2006) ........................................................................................................................... 130
3.10
CONSISTENCE ..................................................................................................................................................................................... 133

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3.11
CUTANIC FEATURES.......................................................................................................................................................................... 134
3.12
POROSITY ............................................................................................................................................................................................. 136
3.13
CEMENTATION AND COMPACTION ............................................................................................................................................ 136
3.14
NODULES AND OTHER MINERAL CONCENTRATIONS .......................................................................................................... 138
3.15
ROOTS.................................................................................................................................................................................................... 139
3.16
OTHER BIOLOGICAL FEATURES .................................................................................................................................................... 140
3.17
CARBONATES ...................................................................................................................................................................................... 141
3.18
GYPSUM ................................................................................................................................................................................................ 141
3.19
READILY SOLUBLE SALTS (MODIFIED FROM FAO, 2006) .................................................................................................... 142
3.20
MAN-MADE MATERIALS .................................................................................................................................................................. 142
3.21
HUMAN-TRANSPORTED MATERIAL (SIMPLIFIED FROM FAO, 2006) ............................................................................... 143
3.22
SOIL HORIZON DESIGNATION ...................................................................................................................................................... 143
4
REFERENCES ......................................................................................................................................... 143
ANNEX III
– RECOMMENDATIONS FOR LOCATING AND DESCRIBING A SOIL PROFILE ................... 145
ANNEX IV
– FIELD EQUIPMENT .............................................................................................................. 148
ANNEX V
– ADDITIONAL INFORMATION ON COLOUR MEASUREMENTS ......................................... 150
ANNEX VI
– GUIDELINES FOR FIELD ESTIMATES OF TEXTURAL CLASSES ......................................... 151
ANNEX VII
– DETAILED DEFINITIONS, RULES AND CONVENTIONS ON MASTER AND SUBORDINATE
HORIZON SYMBOLS ...................................................................................................................................... 152
1
VOCABULARY ...................................................................................................................................... 152
2
SOIL HORIZON DESIGNATION ............................................................................................................ 154
2.1
MASTER HORIZONS AND LAYERS ...................................................................................................................................................... 154
2.2
TRANSITIONAL HORIZONS ................................................................................................................................................................... 163
2.3
SUBORDINATE CHARACTERISTICS WITHIN MASTER HORIZONS AND LAYERS ................................................................. 163
2.4
VERTICAL SUBDIVISIONS ....................................................................................................................................................................... 165
2.5
DISCONTINUITIES ..................................................................................................................................................................................... 165

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Annex II – Guidelines for Forest Soil Description
0 Introduction
These guidelines are intended to help you to make the necessary field recordings and to collect
other additional information enabling proper description of a forest soil profile and subsequent
classification according to the World Reference Base for Soil Resources (IUSS Working Group WRB,
2015) as asked by the Manual Part X on Sampling and Analysis of Soil. These guidelines elaborate
on variables which are not described elsewhere in this ICP Forests Manual. On the other hand,
information collected in the other surveys can be very relevant to understand and interpret the soil
profile correctly. In that case, reference is made to the concerning Parts of this Manual.
These guidelines are largely based on the FAO (2006) Guidelines for soil description (4th edition) but
do deviate for a number of parameters:
Concerning the horizon designation of the organic layer (master symbol ‘O’), the ICP Forests
Manual continues to use the symbols OL, OF and OH, which is a tradition in the description of
European forest soils whereas the FAO (2006) adopted recently the subordinate symbols i, e and a
from the American soil classification system.
By consequence, there is not need to change the subordinate symbol ‘a’ standing for ‘evidence of
cryoturbation’ as in FAO (1989) into the @ symbol as in FAO (2006).
1 General site information
1.1 Observation plot number
(to be reported in *.PLS, *.PRF, *.PFH, *.SOM and *.LQA file)
The observation plot number is the unique number given to each plot. It is reported with 4 digits.
Example: Observation plot number [1012]
1.2 Profile ID
(to be reported in *.PRF and *.PFH file)
The soil profile identification number/code. It is reported with 4 characters.
Example: Profile number [0149]
1.3 Date of profile description
(to be reported in *.PRF file)
The date of description in forms how old the data are and in what season they are recorded. The
date of description is given as DDMMYY (6 digits).

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Example: 160504 (16 May 2004)
1.4 Profile latitude-/ longitude coordinates
(to be reported in *.PRF file)
The coordinates of the centre of the observation plot is mandatory information. In addition it is
also recommended to record the latitude and longitude coordinates of the soil profile pit as
accurately as possible (in degrees and sexagesimal minutes and seconds). The point observation of
the soil profile is the central point of the described soil profile wall.
If possible, by preference a Global Positioning System (GPS) is used. If recording of the soil profile
coordinates is impossible, then the distance (in metres and centimetres) and direction (in degrees)
from the experimental plot centre should be measured and recalculated in coordinates.
The location of the profile pit is reported as:
Latitude geographic coordinates (+/- degrees, minutes, seconds) [WGS84]
Longitude geographic coordinates (+/- degrees, minutes, seconds) [WGS84]
Example:
Latitude:
51° 23´ 31´´ N; is reported as +512331

Longitude:
11° 52´ 40´´ E; is reported as +115240
1.5 Elevation
(to be reported in *.PRF file)
The elevation or altitude (m above sea level) of the site should be obtained as accurately as
possible.
2 Soil forming factors
Although the description of the soil forming factors are important for the correct interpretation of
the soil profile, the soil module of the database does not ask to report most of these parameters,
except for land use, parent material, water availability, mean highest and mean lowest
groundwater level, profile depth (root, rock, obstacle depths). On the other hand, FSCC strongly
recommends to record and store all soil forming variables at national level. The information may be
derived from a combination of field measurements/observations, climatic records, topographical,
geological and geomorphological maps and documents, and partly from the other surveys already
conducted on the observation plots.
2.1 Climate and weather conditions
For the collection of meteorological data, see Manual IX on Meteorological Measurements.
2.1.1
Present weather conditions
The weather condition at the time of the profile description is recorded, using following classes
(after BBC weather)

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Code
Description
1
sunny
2
partly cloudy
3
overcast
4
light rain
5
heavy rain
6
thunder storm
7
sleet 1)
8
hail 2)
9
snow

1) Sleet refers to snow that has partially melted when it touches the ground, due to surrounding air that is sufficiently
warm to partially melt it while falling, but not warm enough to fully melt droplets into rain. Thus it refers to partially
melted droplets, a mixture of snow and rain. It does not tend to form a layer on the ground, unless the ground has a
temperature that is below freezing, when it can form a dangerous layer of invisible ice on surfaces known as 'black ice'.
This similarly occurs when rain freezes upon contact with the ground (freezing rain) [http://en.wikipedia.org/].

2) Hail is a type of graupel, a form of precipitation, composed of spears or irregular lumps of ice. It occurs when
supercooled water droplets (remaining in a liquid state despite being below the freezing point, 0 °C) in a storm cloud
aggregates around some solid object, such as a dust particle or an already-forming hailstone. The water then freezes
around the object. Depending on the wind patterns within the cloud, the hailstone may continue to circulate for some
time, increasing in size. Eventually, the hailstone falls to the ground, when the updraft is no longer strong enough to
support its weight (http://en.wikipedia.org/).
2.1.2
Former weather conditions (AG-Boden, 2004)
This refers to the weather conditions prior to the time of the profile description.

Code
Description
1
no rain during the last month
2
no rain during the last week
3
no rain during the last 24 hours
4
light rain during the last 24 hours
5
heavy rain or thunder during the last 24 hours
6
extremely rainy or snow melting
2.2 Soil climate
2.2.1
Cryic horizon
Providing information on the soil climate is optional, except for those soils that may have a cryic
horizon1 . A cryic horizon has following definition with respect to soil temperature:
A cryic horizon must have a soil temperature at or below 0°C for two or more years in succession.
2.2.2
Soil climate classification (FAO, 2006)
The soil climate classification can be indicated, if applicable. The soil moisture and temperature
regimes according to the USDA Keys to Soil Taxonomy (Soil Survey Staff, 2003) may be used. Where
such information is not available or cannot be derived from representative climatic data with

1 Note that the temperature requirement for a cryic diagnostic horizon is different than for a cryic soil temperature
regime. Whereas the temperature for the cryic soil temperature regime is measured at 50 cm depth, the cryic horizon
may be present in all depths within the upper 100 cm to qualify for Cryosols, or within the upper 200 cm for other
reference soil groups.

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confidence, it is better to leave the space blank. Other agro-climatic variables worth mentioning
would be a local climate class, the agro-climatic zone and length of growing period.
Soil Temperature Regime
Soil Moisture Regime
Code Description
Code
Description
Code
Description
Code Description
PG
Pergelic

AQ
Aquic
PQ
Peraquic
CR
Cryic

AR
Aridic

FR
Frigid
IF
Isofrigid
TO
Torric

ME
Mesic
IM
Isomesic
UD
Udic
PU
Perudic
TH
Thermic
IT
Isothermic
US
Ustic

HT
Hyperthermic
IH
Isohyperthermic
XE
Xeric

2.3 Topography
2.3.1
Slope position
(after FAO, 2006)
The position of the soil profile with respect to the slope is very important. Not only will the slope
position have an influence on the external and internal drainage, but also the runoff and the
subsurface flow are affected. A separate terminology is used for flat or almost flat (slopes of <10%)
and undulating to mountainous terrains (slopes >10%) (Figure 1):

Position in flat or almost flat terrain
Position in undulating to mountainous terrain
Code
Description
Code
Description
1
Higher part (rise)
5
Crest (summit)
2
Intermediate part
6
Upper slope (shoulder)
3
Lower part (and dip)
7
Middle slope
4
Bottom (drainage line)
8
Lower slope (foot slope)

9
Toe slope

10
Bottom (flat)
Figure 1: Slope positions in undulating and mountainous terrain (after Ruhe, 1975; Schoeneberger et al.,
2002; FAO, 2006)
2.3.2
Slope form
(after Schoeneberger et al., 2002; FAO, 2006)
The slope form is described in two directions: up and down slope, which is perpendicular to the
contour, and across slope, which is along the horizontal contour. The slope form classes defined are
provided in Figure 2:
Channel
5
6
8
9
7
5
10
8
6
7
Alluvium

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Code

Description

SS
VS
CS
SV
VV
CV
SC
VC
CC
surface flow pathway
Figure 2: Slope forms and surface drainage path-
ways (after Schoeneberger et al., 2002)
1
SS
Straight, straight
2
SV
Straight, convex
3
SC
Straight, concave
4
VS
Convex, straight
5
VV
Convex, convex
6
VC
Convex, concave
7
CS
Concave, straight
8
CV
Concave, convex
9
CC
Concave, concave
10

Terraced
11

Complex (irregular)
2.3.3
Slope gradient
(Modified from FAO, 2006)
The slope gradient in the immediate surrounding of the soil profile should be measured using a
clinometer, an abney level or a similar instrument. If measurements in the field are not possible,
then the gradient can be calculated from the contour lines on detailed topographical maps.
In practice, measuring slopes in forest can be problematic especially when the slope gradient is
very gentle because then a longer distance is necessary to make an accurate measurement. If so, it
is advised to base very gentle gradients (<2%) on topographical map readings.
If the slope gradient is measured in degrees, then the gradient is calculated into percent, knowing
that 45° equals 100%. Values above 100% are possible (often such steeps slopes are indeed left for
forests).

Code
Description
Class limits
1
Flat
0 – 0.2 %
2
Level
0.2 – 0.5 %
3
Nearly level
0.5 – 1.0 %
4
Very gently sloping
1 – 2 %
5
Gently sloping
2 – 5 %
6
Sloping
5 – 10 %
7
Strongly sloping
10 – 15 %
8
Moderately steep
15 – 30 %
9
Steep
30 – 60 %
10
Very steep
60 – 100 %
11
Extremely steep
>100 %
2.3.4
Slope length (FAO, 2006)
In addition to the above attributes of slope, the slope length along the slope (particularly above
the site) is recorded in meters.
2.3.5
Slope orientation
The slope orientation (azimuth) of the plot is mandatory to report in the general plot file at the
time of the installation of the monitoring plot (XXGENER.PLT file) according to classes. See Part II of
this Manual.

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2.4 Land use
(to be reported in *.PRF file)
Land use applies to the current use of the land. Land use greatly influences the direction and rate
of soil formation; its recording greatly enhances the interpretative value of the soil data. The land-
use should be described according to following list:

Code
Description
50
Natural forest and woodland (mostly natural regeneration)

51
Natural forest and woodland without felling

52
Natural forest and woodland with selective felling

53
Natural forest and woodland with clear felling

60

Plantation forestry (mostly planted)

61
Plantation forestry without felling

62
Plantation forestry with selective felling

63
Plantation forestry with clear felling

70
Agro-forestry
80
Nature protection
90
Other (explain)
Further information:
•
Is hunting allowed? (Y/N/X; where X stands for no information)
•
Is the wild life protected including density control? (Y/N/X; where X stands for no information)
•
Is grazing by domesticated animals (e.g. cattle, pigs…) practised, or not? (Y/N/X; where X
stands for no information)
2.5 Human influence
(modified from FAO, 2006)
Any evidence of human activity, which is likely to have affected the landscape or the physical and
chemical properties of the soil should be recorded (erosion is dealt with separately, see paragraph
2.16). Below are the most common examples of human influence listed. Observations of human
impact on the soil profile is reported in chapter 3.20 (Man Made Materials) and 3.21 (Human
Transported materials). Here only observations observed in the landscape on meso and micro scale
are recorded.
Code
Description
Code
Description
1
No influence
15
Raised beds
2
Vegetation disturbed (not specified)
16
Terracing
3
Vegetation slightly disturbed
17
Land fill
4
Vegetation moderately disturbed
18
Levelling
5
Vegetation strongly disturbed
19
Artificial drainage
6
Mineral additions (not specified)
20
Irrigation (not specified)
7
Sand additions
21
Clearing
8
Organic additions (not specified)
22
Burning
9
Ploughing (not specified)
23
Surface compaction
10
Shallow ploughing (<20 cm)
24
Traffic traces
11
Ploughing (20-40 cm)
25
Application of fertilizers
12
Deep ploughing (>40 cm)
26
Pollution
13
Spitting (traces of spade marks)
30
Others (explain)
14
Plaggen

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2.6 Vegetation
2.6.1
Forest type classification
The forest type is described, according the European forest type classification, which was validated
in the BioSoil biodiversity project of the majority o the Level I plots (EEA, 2007). On Level I, Level II
and the Level II core plots, the forest type should be described in the general plot file (see Manual
Part II).
2.6.2
Tree species composition
The main tree species together with the type of tree species mixture (single tree wise mixture,
group wise mixture, mixture by layers, etc.) is to be reported in the general plot file at the
installation of the monitoring plot. See Manual Part II. The social class is mandatory to report on
Level II for crown condition assessment.
2.7 Parent material
(originating from Finke et al. 2001; to be reported in *.PRF file)
The parent material is the material from which the soil has been derived and in which the soil
profile has been developed. There are two groups of parent material: either unlithified materials
(mostly sediments), or weathering materials overlying the hard rock from which they originate.
There are also restored natural soil materials or sediments as well as man-made (technogenic)
materials.
The detailed table on parent material applied by the Soil Geographical Data Base (-Finke et al.
2001) is presented in the explanatory items. The parent material should be described at least on
the major class level. The 9 major classes summarised below are not listed hierarchically:
Code
Description of Major Class level
0000
No information
1000
Consolidated-clastic-sedimentary rocks
2000
Other sedimentary rocks (chemically precipitated, evaporated, or organogenic or biogenic in
origin)
3000
Igneous rocks
4000
Metamorphic rocks
5000
Unconsolidated deposits (alluvium, weathering residuum and slope deposits)
6000
Unconsolidated glacial deposits / glacial drift
7000
Aeolian deposits
8000
Organic materials
9000
Anthropogenic deposits
2.8 Natural Drainage Classes
(Soil Survey Staff, 1993)
Soil drainage is usually reflected by soil colour, but relict features may persist after natural or
artificial changes in drainage. The depth of occurrence and intensity of gley features usually
indicate the drainage status of the soil but not always: some soil materials will not develop strong
features of gleying because of their specific chemical composition, texture, structure or porosity,
other mottles may be the results of weathering minerals, rather than an impact of drainage
conditions.

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Code
Class name
Description
1
Excessively drained
Water is removed from the soil very rapidly. Internal free
(“gravitational”) water commonly is very rare or very deep. The
soils are commonly coarse-textured, and have very high
saturated hydraulic conductivity, or are very shallow.
2
Somewhat excessively
drained
Water is removed from soil rapidly. Internal free water occurrence
commonly is very rare or very deep. The soils are commonly
coarse-textured, and have high saturated hydraulic conductivity
or are very shallow.
3
Well drained
Water is removed from the soil readily, but not rapidly. Internal
free water occurrence commonly is deep or very deep; annual
duration is not specified. Wetness does not inhibit growth of
roots for significant periods during most growing seasons. The
soils are mainly free of the deep to redoximorphic features that
are related to wetness.
4
Moderately well drained
Water is removed from the soil somewhat slowly during some
periods of the year. Internal free water commonly is moderately
deep and may be transitory or permanent. The soil is wet for only
a short time within the rooting depth during the growing season,
but long enough that most mesophytic crops are affected. The
soil commonly has a moderately low or lower saturated hydraulic
conductivity within 1 m of the surface, or periodically receives
high rainfall, or both.
5
Somewhat poorly drained
Water is removed slowly so that the soil is wet at a shallow depth
for significant periods during the growing season. Internal free
water is commonly shallow to moderately deep and transitory to
permanent. Unless the soil is artificially drained, the growth of
most mesophytic plants is markedly restricted. The soil
commonly has a low or very low saturated hydraulic conductivity
or a high water table, or receives water from lateral flow, or
persistent rainfall, or some combination of these factors.
6
Poorly drained
Water is removed so slowly that the soil is wet at shallow depths
periodically during the growing season or remains wet for long
periods. Internal free water is shallow to very shallow and
common or persistent. Unless the soil is artificially drained, most
mesophytic crops cannot be grown, unless the soil is artificially
drained. The soil, however, is not continuously wet directly below
ploughing depth (±25 cm). Free water at shallow depth is usually
present. The water table is commonly the result of low or very
low saturated hydraulic conductivity or persistent rainfall, or a
combination of both factors.
7
Very poorly drained
Water is removed from the soil so slowly that free water remains
at or near the soil surface during much of the growing season.
Internal free water is very shallow and persistent or permanent.
Unless the soil is artificially drained, most mesophytic crops
cannot be grown. The soils are commonly level or depressed and
frequently ponded. If rainfall is persistent or high, the soil can be
very poorly drained even on gentle slopes.
X
Not known

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2.9 Water availability
(to be reported in *.PLS file)
An estimate of the water availability to principal tree species during the growing season is made:

Code
Description
1
Insufficient
2
Sufficient
3
Excessive
2.10 Period of water saturation
(FAO, 1990)
In the description of drainage classes, the period when the soil is saturated or very wet is not
satisfactory, especially where the rainfall is strongly seasonal or irregular. Very permeable sands
may be permanently or seasonally waterlogged and impermeable clays may never be saturated or
only for a few days a year.
The period during which the soil near the surface is saturated should be indicated, based on local
information or judgment supplemented by gleying features in the profile:

Code
Description
1
Never saturated
2
Rarely saturated (a few days in some
years)
3
Saturated for short periods in most years
(up to 30 days)
4
Saturated for long periods every year
5
Always saturated
2.11 External drainage
(FAO, 1990)
The external drainage of a site refers to its relative position in the landscape. Is the site in a
landscape position where it will overall receive water from upslope or rather shed water
downslope? And if shedding, by which speed is the water lost? The following classes are defined:

Code
Description
1
Ponded (run-on site)
2
Neither receiving nor shedding water
3
Slow run-off
4
Moderately rapid run-off
5
Rapid run-off

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2.12 Flooding
(FAO, 1990)
Flooding is described according to its frequency, duration and depth. At most sites it is difficult to
assess flooding accurately. Information may be obtained from records of past flooding or from
local enquiry. The frequency and duration classes give an indication of the average occurrence of
flooding. It is very important to evaluate if the flooding is a relict or if it is still active at present.
2.12.1 Frequency

Code
Description
1
Daily
2
Weekly
3
Monthly
4
Annually
5
Biennially
6
Once every 2-4 years
7
Once every 5-10 years
8
Rare (less than once in 10 years)
9
Inactive today, but has been active in
historical time
10
Inactive today, but has once been active
(ancient time)
11
None
2.12.2 Duration (days/year)

Code
Description
1
Less than 1 day
2
1- 15 days
3
15- 30 days
4
30- 90 days
5
90 -180 days
6
180- 360 days
2.12.3 Depth (of standing water)

Code
Description
Class limits
1
Very shallow
0 - 25 cm
2
Shallow
25 - 50 cm
3
Moderately deep
50 - 100 cm
4
Deep
100 - 150 cm
5
Very deep
> 150 cm
2.13 Groundwater table
(Modified from SG-DBEM, 2003)
The groundwater table level within or below a soil profile often varies in time. Therefore, the mean
highest and mean lowest permanent or perched groundwater table level should be the average for
at least the past 10 years. This information can in some cases be derived from maps. Seasonal
variations are not recorded. The different groundwater table classes to be used are as follows:

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2.13.1 Mean highest and mean lowest groundwater table
(to be reported in *.PRF file)
The mean highest and mean lowest permanent or perched groundwater table level is the average
level for at least the past 10 years. Generally this information is lacking and so these values need
generally to be estimated by an expert.
The depth classes for groundwater for mean lowest and mean highest depth levels are:

Code
Description
Class limits
9
No water table observed or unknown
1
Very shallow to shallow
0 - 50 cm
2
Moderately deep
50 - 100 cm
3
Deep
100 - 150 cm
4
Very deep
150 - 200 cm
5
Extremely deep
>200 cm
2.13.2 Type of water table
(to be reported in *.PRF file)

Code
Description
9
No water table
1
Perched water table
(= stagnating water table)
2
Permanent water table
( = groundwater table)
2.14 Rock outcrops
(after FAO, 2006)
Rock outcrops should be described in terms of percentage surface cover, size and spacing of the
individual outcrops. It is necessary to walk around in increasing larger circles around the profile
plot in order to make a correct estimate. The classes of percentage of surface cover and of average
distance between rock outcrops (single or clusters) are as follows:
2.14.1 Surface cover

Code
Description
Class limits
1
None

0 %
2
Very few

0 - 2 %
3
Few

2 - 5 %
4
Common

5 - 15 %
5
Many

15 - 40 %
6
Abundant

40 - 80 %
7
Dominant

>80 %
8
Rock outcrops are present but mostly hidden
below forest litter

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2.14.2 Distance between rock outcrops

Code

Description
1

>50 m
2

20 - 50 m
3

5 - 20 m
4

2 - 5 m
5

<2 m
2.15 Coarse surface fragments
(FAO, 2006)
Coarse surface fragments, boulders and stones, including those that are partly buried, should be
described in terms of percentage of surface cover and size of the fragments. It is often not easy to
observe boulders and stones under forest due to the litter layer, so a careful survey may be
necessary. Remember, a stone or boulder partly buried is only included in the coverage and class
estimate based on the visible part, it is not the purpose to uncover partly or completely buried
coarse fragments. The classes of coverage and size handled are:
2.15.1 Surface cover
Code
Description

Class limits
9
None

0 %
1
Very few

0 - 2 %
2
Few

2 - 5 %
3
Common

5 - 15 %
4
Many

15 - 40 %
5
Abundant

40 - 80 %
6
Dominant

>80 %
2.15.2 Size classes
Size classes according to the greatest dimension of the individual gravels/stones:
Code
Description
Class limits
1
Fine gravel

0.2 - 0.6 cm
2
Medium gravel

0.6 - 2.0 cm
3
Coarse gravel

2 - 6 cm
4
Stones

6 - 20 cm
5
Boulders

20 - 60 cm
6
Large boulders

- 200 cm
2.16 Erosion and sedimentation
(modified from FAO, 2006)
Although under most forest covers erosion and sedimentation will be of minor importance, these
variables have been included in these guidelines. Since, when it is present, it is of great importance
for the soil formation and dynamics.
2.16.1 Type of erosion/sedimentation
Erosion and sedimentation can be described according to the agency - water, wind, mass
movements (landslides and related phenomena). In forested sites the major or only erosion may

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occur along patches, roads, timber tracks etc. Description should also include deposition of
transported material:
Code
Description
9
No evidence of erosion
1
Water erosion and sedimentation
2
Sheet erosion by water
3
Rill erosion by water
4
Gully erosion by water
5
Tunnel erosion by water
6
Mass movement (landslides and similar phenomena)
7
Sedimentation by water
8
Wind erosion and sedimentation
9
Sedimentation by wind
10
Shifting sands
11
Salt deposition
12
Other erosion/sedimentation, related to human
2.16.2 Area affected
The proportion of total area affected by erosion/sedimentation is estimated:
Code
Description
9

0 %
1

0 - 5 %
2

5 - 10 %
3

10 - 25 %
4

25 - 50 %
5

> 50 %
2.16.3 Degree
It is difficult to define classes of the degree of erosion which are equally appropriate for all soils,
environments, and the various types of erosion. Classes may have to be defined further for each
type or combination of erosion and sedimentation and each specific environment. For example, in
the case of gully and rill erosion, the depth and spacing may be recorded; for sheet erosion the loss
of topsoil; for dunes the height; for sedimentation the thickness of the layer. The following classes
are recommended to describe the degree of erosion:
Code
Class name
Description
9
None
No erosion nor sedimentation
1
Heavy sedimentation
Soils buried below >50 cm of accumulated
sediment
2
Considerable sedimentation
Soils buried below 5 - 50 cm of accumulated
sediment
3
Noticeable sedimentation
Soils buried below <5 cm of accumulated sediment,
continuously distributed
4
Traces sedimentation
Soils buried below <5 cm of accumulated sediment,
discontinuously distributed
5
Slight erosion
Some evidence of damage to the topsoil; original
biotic functions largely intact
6
Moderate erosion
Removal of topsoil; original biotic functions partly
destroyed
7
Severe erosion
Surface layers completely removed and subsurface
layers exposed
8
Extreme erosion
Substantial removal of deeper subsurface horizons
(badlands)

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2.16.4 Activity
The period of activity of accelerated erosion, or sedimentation, may be described as follows:
Code
Description
9
Accelerated and natural erosion not observed
1
Period of activity not known
2
Active in historical times
3
Active in recent past (up till past 50 - 100 years)
4
Active at present
2.17 Surface sealing
(FAO, 2006)
Where the mineral soil is exposed, a surface crust may develop. Only in extreme cases a surface
sealing will develop on forest soils, as the soil should be exposed to wetting and drying and not be
protected by a litter layer. If surface crusts develop it will have a negative effect on seed
germination, reduce water infiltration and increase run-off. The thickness and the consistence of
the crust is described (for consistence definitions see paragraph 3.11):
2.17.1 Thickness
Code
Description
Class limits
9
None

1
Thin

<2 mm
2
Medium

2 - 5 mm
3
Thick

5 - 20 mm
4
Very thick

>20 mm
2.17.2 Consistence when dry
Code
Description
1
Slightly hard
2
Hard
3
Very hard
4
Extremely hard
2.18 Surface cracks
(FAO, 2006)
Mineral surface cracks develop in many clay-rich soils during drying. The width (average, or
average width and maximum width) of the cracks, and the average spacing between cracks are
measured.
2.18.1 Size (Width)
Code
Description
Class limits
1
Fine

<1 cm
2
Medium

1 - 2 cm
3
Wide

2 - 5 cm
4
Very wide

5 - 10 cm
5
Extremely wide

>10 cm

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2.18.2 Distance between cracks
Code
Description
Class limits
1
Very closely spaced

<0.2 m
2
Closely spaced
0.2 - 0.5 m
3
Moderately widely
spaced
0.5 - 2 m
4
Widely spaced

2 - 5 m
5
Very widely spaced

>5 m
2.19 Salt
(FAO, 2006)
The occurrence of surface salt may be described in terms of cover and appearance. Classes for the
percentage of surface cover and thickness are:
2.19.1 Cover
Code
Description
Class limits
9
None

0 - 2 %
1
Low

2 - 15 %
2
Moderate
15 – 40 %
3
High
40 – 80 %
4
Dominant

>80 %
2.19.2 Thickness
Code
Description
Class limits
1
Thin

<2 mm
2
Medium
2 - 5 mm
3
Thick
5 - 20 mm
4
Very thick
>20 mm
2.20 Profile depth
(to be reported in *.PRF file)
The depth of the soil is defined with 3 attributes: effective rooting depth, rock depth and obstacle
depth. The depth must be given in cm from the top of the mineral soil surface.
The ‘Effective rooting depth’ is defined as the depth of the soil at which root growth is strongly
inhibited. As rooting depth is plant specific, it is recommended that representative species are used
to indicate the effective rooting depth of the soil. The effective rooting depth is governed by such
factors as the presence of cemented, toxic or compacted layers, hard rock, or indurated gravel
layers. A high permanent water table may also control the rooting depth, but may change after
drainage. The effective hydrological depth may be much greater. Apart from obvious situations
such as the presence of hard rock, it is realized that the estimation of effective soil depth is subject
to individual interpretation.
The depth to the underlying bedrock should be recorded under ‘Rock depth of the soil profile’.
The field ‘Obstacle depth of the soil profile’ can be used to record the depth to any other limiting
horizon, such as a petrocalcic horizon, fragipan, duripan, waterlogging, accumulation of toxic
elements.

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3 Soil horizon description
In the following chapter, the horizon variables are presented. The sequence is different from those
presented in the FAO guidelines (FAO 1990; FAO 2006).
Usually a forest soil is composed of mineral and organic horizons, stones, bedrock etc., which
together constitute the soil profile. In the following chapter a series of variables are listed, but not
all of them are equal relevant to particular organic horizons. For the definitions of organic material
and organic horizons, see Annex 7.
In principle knowledge of the content of organic matter is required to differentiate between
organic and mineral materials. In the field, organic horizons are usually easy to recognise, only
border cases will need analytical data to check for the content of organic carbon. In the table below
the subchapters relevant for organic and mineral horizons are summarised:
Relevant for:
organic horizons
mineral horizons
3.1 Horizon boundary
Yes
Yes
3.2 Photographic recordings
Yes
Yes
3.3 Soil Colour
Yes
Yes
3.4 Mottling
No
Yes
3.5 Redoximorphic properties
Yes
Yes
3.6 Texture
No
Yes
3.7 Rock fragments
Yes
Yes
3.8 Andic material
No
Yes
3.9 Soil structure
No
Yes
3.10 Consistence
No
Yes
3.11 Cutanic features
No
Yes
3.12 Porosity
Yes
Yes
3.13 Cementation and compaction
No
Yes
3.14 Nodules
No
Yes
3.15 Roots
Yes
Yes
3.16 Other biological features
Yes
Yes
3.17 Carbonates
Yes
Yes
3.18 Gypsum
No
Yes
3.19 Readily soluble salts
Yes
Yes
3.20 Man-made materials
Yes
Yes
3.21 Human transported material
No
Yes
3.22 Soil horizon designation
Yes
Yes
After having selected the most representative location for the soil profile (see also Annex 3), the
profile is opened and cleaned. A list of suggested field equipment is presented in Annex 4. The
recommended sequence of description is as follows:
•
delineation and description of the horizon boundaries,
•
photographic recordings of the soil in general and of special features in detail,
•
colour measurements (see also Annex 5),
•
from this stage on, the profile wall is gently broken apart to record texture, rock fragments,
structure, consistence, porosity, cutans, cementations and nodules, this is followed by
•
the description of roots and other biological activity, and by
•
the description of carbonates, gypsum and salts,
•
each horizon is designated one or more horizon master and subordinate symbols, and
•
the necessary samples are collected.

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3.1 Horizon boundary (modified from FAO, 2006)
The nature of the boundaries between soil layers, or horizons, may indicate the processes that have
formed the soil. In some cases, they reflect anthropogenic impacts. Horizon boundaries are
described in terms of depth, distinctness and topography.
3.1.1
Horizon number
(to be reported in *.PFH file)
After delineation of the horizon boundaries, each horizon is numbered: 1, 2, 3 etc. While the
horizon symbols may change according to new information, the horizon number is not to be
changed at any point of the further profile description and sampling. The numbering starts from
the interface between air and soil no matter whether the surface horizon is an organic or a mineral
horizon (see Figure 3). If at a later stage, a new horizon is discovered or an existing horizon is
subdivided, a new number should be created. Avoid renumbering of the existing horizons to keep
the link with the initial description in the field.
3.1.2
Depth of horizon limits
(to be reported in *.PFH file)
The depth of the upper and lower boundary of each horizon is measured in centimetres from the
surface of the mineral soil.
If the soil is covered by (an) organic layer(s), either:
(a) 10 cm or more thick from the soil surface to a lithic or paralithic contact, or
(b) 40 cm or more thick,
then the depth is measured from the surface of the organic cover. The depth requirements
correspond to the limit for Histosols (organic soils).

Figure 3: Examples on how the horizon depth should be recorded in the field. These depths are
important for the profile description and for the sampling.
•
If the organic layer(s) is (are) too shallow to fulfil the above depth requirement(s), then its depth
is recorded from the zero-point and upwards (see Figure 3), using negative depths.
•
The depth is measured perpendicular to the slope.
•
Most soil boundaries are zones of transition rather than sharp breaks. The distinctness together
with the topography describe the transition between the different horizons and substitute for
the need to describe the depth ranges as for instance from 28 (25-31) cm to 45 (39-51) cm.
Depth
H1: OL
-7-0 cm
Depth
H1: OL
+30-26 cm
Depth
H2: OH
+26-0 cm
H1: A
0-12 cm
H3: A
0-12 cm
H2: A
42-54 cm
H3: A
42-54 cm
H2: E
12-20 cm
H4: E
12-20 cm
H3: E
54-62 cm
H4: E
54-62 cm
H3: B
20-70 cm
H5: B
20-70 cm
H4: B
62-112 cm
H5: B
62-112 cm
H4: C
70-100 cm
H6: C
70-100 cm
H5: C
112-142 cm
H6
C
112-142 cm
H
0-42 cm
0-42 cm
H
H1:
H2:

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a digital camera, use a high resolution (5 Mega Pixels or more) and a camera with a good quality
lens. The photographic database can/should include following images:
•
General photo illustrating the geomorphology and vegetation of the area surrounding the
profile
•
Photo of the immediate vicinity of the profile
•
The profile after cleaning and before indication of the soil horizons on the profile wall.
•
The profile after the soil horizons are outlined gently on the profile wall with e.g. a knife
•
The profile with partly visible structure and partly with a cleaned surface
•
The profile with indications where to sample
•
Close-up of the organic topsoil horizon(s)
•
Horizontal sections, e.g. in de depths where the bulk density (BD) is sampled
•
Special features
3.3 Soil colour
(to be reported in *.PFH file)
The colour of the soil matrix in each horizon should be recorded in moist and dry condition using
the Munsell notation (e.g. Munsell, 2000). The colour notation is composed of hue, value and
chroma. Hue is the dominant spectral colour (red, yellow, green, blue, violet), value is the lightness
or darkness of colour ranging from 1 (dark) to 8 (light), and chroma is the purity or strength of
colour ranging from 1 (pale) to 8 (bright). If there is no dominant colour, the horizon is described as
mottled and two or more colours are given, making use of the observation field. In addition to the
colour notations, the standard Munsell colour names should be recorded as well.
Example:
Greyish brown 10YR 5/2 (moist) and light brownish grey 10YR 6/2 (dry);

where 10YR (yellowish red) is the hue, 5 (or 6) is the value and 2 the chroma.
Example:
Dark greyish brown to greyish brown 2.5Y 4.5/2 (moist) and light brownish grey

2.5Y 6/2 (dry);

Notice that interpolation between colours is possible for hue, value and/or chroma
Example:
Dark greenish grey 5GY 4/1 (moist) and greenish grey 10GY 5/1 (dry);

where 5GY or 10GY (greenish yellow) is the hue, 4 (or 5) is the value and 1 is the

chroma.
More detailed information about optimal colour measurements and special colours required for
soil classification is to be found in Annex 5.
3.4 Mottling
(FAO, 2006)
Mottles are spots of different colours interspersed with the dominant colour of the soil. They
commonly indicate that the soil has been subject to alternate wet (reducing) and dry (oxidizing)
conditions. Other mottles can be the result of rock weathering, clay (+iron) migration and
accumulation, selective decay by fungi of organic matter etc.

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Mottling is described in terms of abundance, size, contrast, boundary and colour. In addition, the
shape, position or any other feature may be recorded.
3.4.1
Colour
Measure the colours using the Munsell Soil Colour Charts.
If the colour changes after exposure to the air, measure both the colours before and after
oxidation.
3.4.2
Abundance
Abundance is described as an exact figure or in classes indicating the percentage of the exposed
surface occupied by the mottles. When mottles are so abundant that distinction of matrix and
mottle colour is not possible, the predominant colours should be described as soil matrix colours.
Code
Description
Class limits
1
None

0 %
2
Very few

0 - 2 %
3
Few

2 - 5 %
4
Common

5 - 15 %
5
Many

15 - 40 %
6
Abundant

>40 %
3.4.3
Size
The following classes are used to indicate the approximate diameters of individual mottles.
Code
Description
Class limits
1
Very fine

< 2 mm
2
Fine

2 - 6 mm
3
Medium

6 - 20 mm
4
Coarse
20 - 40 mm
5
Very coarse
40 - 80 mm
6
Extremely coarse

> 80 mm
3.4.4
Contrast
The colour contrast between mottles and soil matrix can be described as:
Code
Description
1
Faint: mottles are evident only on close examination. Soil colours in both the matrix and mottles
are similar.
2
Distinct: although not striking, the mottles are readily seen. The hue, chroma or value of the
matrix is easily distinguished from the mottles. They may vary by as much as 2.5 units of hue or
several units in chroma or value.
3
Prominent: the mottles are conspicuous. Hue, chroma and value, alone or in combination, are
several units apart.
3.4.5
Boundary
The boundary between mottle and matrix is described according to the width of the transition
zone.
Code
Description
Class limits
1
Sharp

<0.5 mm
2
Clear
0.5 - 2 mm
3
Diffuse

2 - 5 mm
4
Very diffuse

>5 mm

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3.5 Redoximorphic properties (IUSS Working Group WRB, 2015)
Redoximorphic features concerns a colour pattern observed in the soil, which is the result of
depletion or concentration compared to the matrix colour, formed by oxidation/reduction of iron
and/or manganese.
3.5.1
Reducing conditions
If reducing conditions prevail in a soil horizon, it can be tested in following ways:
•
Is the negative logarithm of the hydrogen partial pressure (rH, calculated as Eh 29-1 + 2pH) less
than 20?
•
Are Fe2+ ions present, as tested by spraying the freshly exposed soil surface with a 0.2% (m/v)
α,α dipyridyl solution in 10% (v/v) acetic acid solution? The test yields a striking reddish colour
in the presence of Fe2+ ions (be careful, the chemical is slightly toxic). Did a reddish colour
(almost like red wine) appear on the tested soil surface after a few minutes?
•
Is iron sulphide present?
•
Is methane present?
If the answer to any of above 4 questions is yes, report:

Y
If none of the test above are positive, report:

N
If data for some reason are missing or impossible to collect, indicate: X
3.5.2
Reductimorphic and oximorphic colours
If oximorphic and/or reductomorphic mottles as present they are first of all described according to
the chapter on mottles (see chapter 3.4). Note that gleyic mottles should be recorded as fast as
possible after the profile has been prepared, sometimes even while digging the profile, due to the
fast oxidation of certain minerals.
•
Are reductimorphic colours, reflecting permanently wet conditions, present on more than 90%
of the soil surface? Reductimorphic colours are neutral white to black (Munsell N1/ to N8/) or
bluish to greenish (Munsell 2.5Y, 5Y, 5G, 5B).
Y/N/X (Yes/No/Not known)
•
Oximorphic colours reflect alternating reducing and oxidizing conditions, as is the case in the
capillary fringe and in the surface horizons with fluctuating groundwater levels. They comprise
any colour, excluding reductimorphic colours (see above). Are 5% or more of the soil surface
cover by oximorphic coloured mottles?
Y/N/X (Yes/No/Not known)
The above described field tests may to some degree illustrate the actual redoximorphic conditions
at the moment of fieldwork, rather than the general condition of the soil. For the same reason it is
strongly recommended in case of gley soils to give special attention to:
•
roots (presence/absence), and
•
the soil water (indications of a fluctuating or permanent water tables etc.)
3.5.3
Stagnic and gleyic colour pattern
Depending on the origin of the water, which is either the groundwater table, either surface water
that is (at least temporarily) saturating the soil layer, two different colour patterns will develop. It is
important to distinguish between both type of colour patterns during the profile description.

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Note: When a stagnic colour pattern is identified in a genetic horizon, it is designated by the
horizon subordinate symbol ‘g’. When a gleyic colour pattern is seen, the horizon received the
subordinate symbol ‘l’. See Annex 7. The latter symbol did not yet exist during the BioSoil
demonstration project (Mikkelsen et al., 2006) and so is only applied in the ICP Forests programme
from 2010 onwards.
Stagnic properties
General description
Soil materials develop stagnic properties (from Latin stagnare, to stagnate) if they are, at least
temporarily, saturated with surface water (or were saturated in the past, if now drained) for a
period long enough that allows reducing conditions to occur (this may range from a few days in
the tropics to a few weeks in other areas).
Diagnostic criteria
Stagnic properties comprise one of the following:
(1) a mottled layer with two or more colours and one or both of the following:

(a) mottles and/or concretions and/or nodules, the colour of which is considered to be

oximorphic, that:

(i) are, if soil aggregates are present, predominantly inside the aggregates; and

(ii) are black, surrounded by lighter-coloured material, or have, moist, a Munsell colour

hue ≥ 2.5 units redder than the surrounding material and a Munsell colour chroma ≥ 1

unit higher than the surrounding material; or

(b) parts, the colour of which is considered to be reductimorphic, that:

(i) are predominantly around root channels, and if soil aggregates are present,

predominantly at or near the surfaces of the aggregates; and

(ii) have, moist, a Munsell colour value ≥ 1 unit higher than the surrounding material and

a Munsell colour chroma ≥ 1 unit lower than the surrounding material; or
(2) a layer with albic material, the colour of which is considered as being reductimorphic, above an
abrupt textural difference; or
(3) a combination of two layers: a layer with albic material, the colour of which is considered as
being reductimorphic, and a directly underlying mottled layer with the colour properties as
specified in diagnostic criterion 1.
Additional characteristics
Stagnic properties result from a reduction of iron and/or manganese (hydr-)oxides around the
larger pores. Mobilized Mn and Fe may be washed out laterally resulting in albic material
(especially in the upper part of the profile that is in many soils coarser textured) or may migrate
into the interiors of the soil aggregates where they are reoxidized (especially in the lower part of
the profile).
If the stagnic properties are weakly expressed, the reductimorphic and oximorphic colours cover
only some parts of the soil volume, and the other parts show the original colour that prevailed in
the soil before the redox processes started. If the stagnic properties are strongly expressed, the
whole volume of the fine earth shows either reductimorphic or oximorphic colours. In the latter
case, the chroma requirements of criteria 1a and 1b sum up to a difference of two units.

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Gleyic properties
General description
Soil materials develop gleyic properties (from Russian gley, mucky soil mass) if they are saturated
with groundwater (or were saturated in the past, if now drained) for a period that allows reducing
conditions to occur (this may range from a few days in the tropics to a few weeks in other areas).
Diagnostic criteria
A gleyic colour pattern shows one of the following:
(1) a layer with ≥ 95% (exposed area) having colours considered to be reductimorphic, that have:

(a) a Munsell colour hue of N, 10Y, GY, G, BG, B, PB, moist; or

(b) a Munsell colour hue of 2.5Y or 5Y with a chroma of . 2, moist; or
(2) a layer with > 5% (exposed area) mottles, the colour of which is considered to be oximorphic,

that:

(a) are predominantly around root channels, and if soil aggregates are present, predominantly

at or near the surfaces of the aggregates; and

(b) have, moist, a Munsell colour hue . 2.5 units redder than the surrounding material and a

Munsell colour chroma . 1 unit higher than the surrounding material; or
(3) a combination of two layers: a layer fulfilling diagnostic criterion 2 and a directly underlying
layer fulfilling diagnostic criterion 1.
Field identification
Gleyic properties results from a redox gradient between groundwater and capillary fringe causing
an uneven distribution of iron and manganese (hydr)oxides. In the lower part of the soil and/or
inside the peds, the oxides are either transformed into insoluble Fe/Mn compounds or they are
translocated; both processes lead to the absence of colours with a hue redder than 2.5 Y.
Translocated Fe and Mn compounds can be concentrated in the oxidized form (Fe[III], Mn[IV]) on
ped surfaces or in biopores (rusty root channels), and towards the surface even in the matrix.
Manganese concentrations can be recognized by strong effervescence using a 10-percent H2O2
solution.
3.6 Texture of the fine-earth fraction
(FAO, 1990) (to be reported in *.PFH file)
Soil texture refers to the proportion of the various particle-size classes in a given soil volume and is
described as soil textural classes (see Figure 5). The 2000 – 63 – 2 μm system for particle-size
fractions is used.
The names of the textural classes, which describe combined particle-size classes, are coded as in
Figure 5. With a lot of training field estimates of the texture can be made, a method for finger
testing of the textural classes is presented in Annex 6. Otherwise calculating the texture class based
on the analytical data from pipette texture is recommended.

Part X

Page 128
Figure 5
adopted
8
5: The fine ea
by FAO (1990
arth by size a
0) and refined
and defined
d by FAO (FAO
in textural c
O, 2006)
classes. Text
Sampling
http://icp-fo
ural classes b
g and Analys
orests.org/ma
based on USD
sis of Soil
anual.htm

DA (1951),

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3.7 Rock fragments
(modified from FAO, 2006)
Large fragments (>2 mm) are described according to abundance, size, shape, state of weathering
and nature of the fragments. The abundance classes correspond with those for surface coarse
fragments and mineral nodules.
3.7.1
Abundance
(to be reported in *.PFH file)
The abundance of rock fragments is estimated (Figure 6) and expressed as a percent (by volume) of
the total soil. By preference, the exact figure is provided rather than abundance classes.

Code
Description (FAO, 2006)
Class limits (volume%)
Description SGDBE
(Lambert et al. 2003)
9
None
0 %
No stones or gravel
1
Very few to few
0 - 5 %
Very few
2
Common
5 - 15 %
Few
3
Many
15 - 40 %
Frequent or many
4
Abundant
40 - 80 %
Very frequent, very many
5
Dominant
>80 %
Dominant or skeletal

Figure 6: Charts for estimating proportions of coarse fragments, mottles or other elements
25 %
30 %
40 %
50 %
75 %
90 %
1 %
3 %
5 %
10 %
15 %
20 %

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http://icp-forests.org/manual.htm
3.7.2
Size of rock fragments and artefacts

Code
Description
Class limits
1
Fine gravel

0.2 - 0.6 cm
2
Medium gravel

0.6 - 2 cm
3
Coarse gravel

2 - 6 cm
4
Stones

6 - 20 cm
5
Boulders

20 - 60 cm
6
Large boulders

60 - 200 cm
3.7.3
Dominant shape of rock fragments

The shape may be described as:
Code
Description
1
Flat
2
Angular
3
Sub-rounded
4
Rounded
3.7.4
State of weathering of rock fragments
The state of weathering is described as:
Code
Description
9
Fresh or slightly weathered: fragments show little or no signs of weathering
1
Weathered: partial weathering is indicated by discolouration and loss of crystal form in the outer
parts of the fragments while the centres remain relatively fresh; fragments have lost little of their
original strength.
2
Strongly weathered: all but the most resistant minerals are strongly discoloured and altered
throughout; the fragments tend to disintegrate under hand pressure.
3.7.5
Nature (type) of rock fragments
The nature of rock fragments is described by the same terminology as for the parent material.
3.8 Andic material
(modified from FAO, 2006)
Soils formed from young volcanic materials often have andic properties: a bulk density of 900
kg/m3 or less, and <10 % clay with a smeary consistence (caused by allophane and/or ferrihydrite).
Surface horizons with andic material are normally black because of the combination of allophane
with humic material, or humic material immobilized by aluminium. Andic material may exhibit
thixotropy, changing under pressure, or by rubbing, from a plastic solid into a liquefied stage and
back into the solid condition.
Is andic material present? Yes/No/Not known (reported as: Y/N/X)
3.9 Soil structure (modified from FAO, 2006)
Soil structure relates to the grouping or arrangement of soil particles into discrete soil units (peds).
The aggregates are separated from each other by pores or voids and are characterised primarily on
basis of their dominant shape: spheroidal (granular, crumb), platy, prism (columnar- top of the
prisms are rounded and prismatic- top of the prisms are level) and blocky (angular blocky and
subangular blocky).

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Figure 7: Soil structure types and their formation (FAO, 2006)
With decreasing soil humidity, the soil structure becomes increasingly pronounced. In moist or wet
conditions, if no clear structure is visible, a large lump of undisturbed soil material can be dried,
which will possible reveal a specific structure. Another method is to take a large lump of soil on the
spade and let it fall from about a meter height, and then to observe how the block of soil breaks
into pieces. A third possibility is to use a knife to gentle loosen the soil material on the profile wall.
Try to loosen the soil in such a way that it breaks along the natural ped faces rather than breaking
through the peds (it demands a bit of practice).
Besides the structure type, also grade and size of aggregates are recorded. When a soil horizon
contains aggregates of more than one grade, size or type, the different kinds of aggregates should
be described separately and their relationship indicated.
3.9.1
Type
(to be reported in *.PFH file)
The soil can be structureless or shows some kind of structure. If a structure is present the degree of
development and the size characteristics to record.
In structureless soil, no aggregates are observable in place and there is no definite arrangement of
natural surfaces of weakness. Structureless soils are subdivided into single grain and massive (see
Figure 7).

Figure 7: Absence of structure, either as single grain (left) or as massive (right) soil material
(http://soil.gsfc.nasa.gov)
Blocky
subangular
Clody
Lumpy
Crumbly
Platy
Columnar
Prismatic
Blocky
angular
Worm-
casts
Granular
Single
grain
Massive
(coherent)
Humus
Iron
Silica
Formed by cementation
from precipitates of
Pedogenic ped formation?
no
yes

Layered
(coherent)
Formed by assemble
(biotic)
Formed by separation
(abiotic)
Formed by fragmentation
or compaction
Carbonates
Gypsum
Cloddy

Part X

Page 132
Structure
Code
1
2
3
4
5
6
7
8
9
10
11
12
13
14
The natu
is possib
Figure 8:
granular,
smaller o
3.9.2
If a struc
granular
equidim
measure
plates ar

2
ed soils:
Structure
name
Platy
Prismatic
Columnar
Angular
Blocky
Subangula
blocky
Granular
Crumbs,
lumps and
clods
Massive
(coherent)
Single grai
Wedge-
shaped
Nutty
Rock struct
Worm cast
Layered
(coherent)
ural types of
ble.
: Illustrations
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Size
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Structure
Code
Size class
Crumbly
/ Blocky
(mm)
Granular / Prismatic /
Columnar / Wedge-shaped
(mm)
Platy

(mm)
1
Very fine or thin
< 5
< 10

< 1
2
Fine or thin
5 - 10
10 - 20
1 - 2
3
Medium
10 - 20
20 - 50
2 - 5
4
Coarse or thick
20 - 50
50 - 100
5 - 10
5
Very coarse or thick
> 50
100 - 500
> 10
6
Extremely coarse
-
> 500

-
3.9.3
Grade
If the structure is not well developed it can be difficult to estimate the degree of development of
the structure, especially if the moisture content is high. Observe if the structural units are well
defined on all sides, or only on a few and how easy the units are separated from each other. Grades
of structured soil materials are defined as follows:
Code
Class
Description
0
None
Structureless, such as for single grain and massive.
1
Weak
Aggregates are barely observable in place and there is only a weak arrangement of natural
surfaces of weakness. When gently disturbed, the soil material breaks into a mixture of few
entire aggregates, many broken aggregates, and much material without aggregate faces.
2
Moderate
Aggregates are observable in place and there is a distinct arrangement of natural surfaces of
weakness. When disturbed, the soil material breaks into a mixture of many entire aggregates,
some broken aggregates, and little material without aggregates faces. Aggregates’ surfaces
generally show distinct differences with their interiors.
3
Strong
Aggregates are clearly observable in place and there is a prominent arrangement of natural
surfaces of weakness. When disturbed, the soil material separates mainly into entire
aggregates. Aggregates’ surfaces generally differ markedly from their interiors.
3.10 Consistence
(FAO, 2006)
Consistence refers to the degree of cohesion or adhesion of the soil mass - friability, plasticity,
stickiness and resistance to compression. It depends on the amount and type of clay, organic
matter and moisture content of the soil.
For reference descriptions, consistence is required for the soil in dry, moist and wet (both stickiness
and plasticity) state. If applicable, thixotropy may be recorded. For routine descriptions, the soil
consistence is described in the natural moisture condition of the profile. Wet consistence can
always be described, and moist conditions if the soil is dry, by adding water to the soil sample.
3.10.1 Consistence when dry
This is determined by breaking the air-dried soil in the hand:
Code
Class
Description
9
Loose
Non-coherent.
1
Soft
Very weakly coherent and fragile; breaks to powder or individual grains under
very slight pressure.
2
Slightly hard
Weakly resistant to pressure; easily broken between thumb and forefinger.
3
Hard
Moderately resistant to pressure; can be broken in the hands but not between
thumb and forefinger.
4
Very hard
Very resistant to pressure; can be broken in the hands only with difficulty.
5
Extremely
hard
Extremely resistant to pressure; cannot be broken in the hands.

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http://icp-forests.org/manual.htm
3.10.2 Consistence when moist
This is determined by squeezing a mass of moist soil material:
Code
Class
Description
9
Loose
Non-coherent.
1
Very friable
Soil material crushes under very gentle pressure, but coheres when pressed
together.
2
Friable
Soil material crushes easily under gentle pressure between thumb and
forefinger, and coheres when pressed together.
3
Firm
Soil material crushes under moderate pressure between thumb and forefinger,
but distinct resistance is felt.
4
Very firm
Soil material crushes under strong pressure; barely crushable between thumb
and forefinger.
5
Extremely
firm
Soil material crushes only under very strong pressure; cannot be crushed
between thumb and forefinger.
3.10.3 Consistence when wet
Stickiness depends on water content and the extent to which soil structure is broken down. Wet
consistence is described in terms of stickiness and plasticity. It should be assessed under standard
conditions on a soil sample in which structure is completely destroyed and which contains just
enough water to create maximum stickiness.
Stickiness is the quality of adhesion of the soil to other objects, assessed by observing its
adherence when pressed between thumb and finger.
Code
Class
Description
9
Non sticky
After release of pressure, practically no soil material adheres to thumb and
finger.
1
Slightly sticky
After pressure, soil adheres to both thumb and finger but comes off one or the
other rather cleanly; it is not appreciably stretched when the digits are
separated.
2
Sticky
Soil adheres to both thumb and finger and tends to stretch and pull apart
rather than pulling free.
3
Very sticky
Soil adheres strongly to both thumb and finger and is decidedly stretched
when they are separated.
Plasticity is the ability of soil material to change shape continuously under stress and to retain the
given shape on removal of stress. It is determined by rolling the soil into a wire about 3 mm in
diameter, then bending the wire.
Code
Class
Description
9
Non plastic
Will not form a wire.
1
Slightly
plastic
Wire can be formed but immediately breaks if bent; soil deformed by very
slight force.
2
Plastic
Wire can be formed but breaks if bent into a ring; slight to moderate force
required for deformation of the soil mass.
3
Very plastic
Wire formed and can be bent into a ring; strong force required for deformation
of the soil.
3.11 Cutanic features
(FAO, 2006)
This section describes clay or mixed-clay illuviation features, coatings of other composition such as
calcium carbonate, manganese, organics or silt; reorientations such as slickensides and pressure
faces, and concentrations associated with surfaces but occurring as stains in the matrix

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(hypodermic coatings). All these features are described according to their type, abundance,
contrast, and location.
3.11.1 Type
The type of coatings may be described, following Schoeneberger et al. (2002), as:
Code
Description
1
Clay
2
Iron oxides (sesquioxides)
3
Clay and iron oxides (sesquioxides)
4
Clay and humus
5
Humus
6
Silt coatings
7
Sand coatings
8
Calcium carbonate
[CaCO3]
9
Silica (opal)

[SiO2·nH2O]
10
Gibbsite

[Al(OH)3]

Jarosite
[KFe3+3(OH)6(SO4)2]
11
Manganese oxide
[Mn2O3]
12
Pressure faces
13
Shiny faces
14
Slickensides2, predominantly intersecting
15
Slickensides, partly intersecting
16
Slickensides, non-intersecting
3.11.2 Abundance
For coatings (cutans), an estimate is made how much of the faces of soil aggregates, stones, or
pores is covered. Similarly, the proportion of the soil layer occupied by lamellae is estimated.
Code
Description
Class
9
None

0 %
1
Very few

0 - 2 %
2
Few

2 - 5 %
3
Common

5 - 15 %
4
Many

15 - 40 %
5
Abundant

40 - 80 %
6
Dominant

>80 %
3.11.3 Contrast
Code
Class
Description
1
Faint
Surface of coating shows little contrast with the adjacent surface. Fine sand grains
are readily apparent in the coating. Lamellae are less than 2 mm thick.
2
Distinct
Surface of coating is smoother than, or different in colour from the adjacent
surface. Fine sand grains are enveloped but their outlines are visible. Lamellae are
between 2 and 5 mm thick.
3
Prominent
Surface of coating contrasts strongly in smoothness or colour with the adjacent
surface. Outlines of fine sand grains are not visible. Lamellae are more than 5 mm
thick.

2 A slickenside, is a term describing the surfaces of the cracks produced in soils containing a high proportion of swelling
clays. Slickensides are a type of cutan (http://en.wikipedia.org/wiki/Slickenside)

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http://icp-forests.org/manual.htm
3.11.4 Location
The location of the coatings is indicated. For pressure faces and slickensides no location is given
since they are, by definition, located on the faces of structural aggregates (ped faces).
Code
Description
9
No specific location
1
Ped faces
2
Horizontal ped faces
3
Vertical ped faces
4
Bridges between sand grains
5
Lamellae (clay bands)
5
Voids
6
Coarse fragments
If the coatings are associated with coarse fragments, following subdivision can be made:
Code
Description
7
Above stones
8
Below stones
9
All around stones
3.12 Porosity
(simplified from FAO, 2006) (to be reported in *.PFH file)
Voids are related to the arrangement of the primary soil constituents and aggregates. They are the
results of rooting, burrowing of animals and other soil forming processes such as cracking,
translocation, leaching. The term void includes all air and water-filled spaces in the soil; the term
pore is often used in a more restrictive way and does not include fissures or planes.
For many purposes, a qualitative description of porosity will suffice. For reference descriptions,
voids are described in terms of type, size and abundance; continuity and orientation may also be
recorded.
The porosity is an indication of the total volume of voids discernible with a x10 hand lens assessed
by area and recorded as the percentage of the surface occupied by pores.
Code
Description
Class limits
1
Very low

<2 %
2
Low

2 - 5 %
3
Medium

5 - 15 %
4
High

15 - 40 %
5
Very high

> 40 %
3.13 Cementation and compaction
(modified from FAO, 2006)
The occurrence of cementation or compaction, as pans or otherwise, is described according to
their nature, continuity, structure, agent and degree. Cemented material does not slake after one
hour of immersion in water.

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3.13.1 Nature (type)
The cementing agent or compaction activity composes of:
Code
Description
1
Gypsum
2
Silica
3
Carbonates
4
Iron oxides
5
Iron-manganese oxides
6
Iron-organic matter
7
Organic matter
8
Others
9
Not known
3.13.2 Continuity

Code
Class
Description
1
Broken
The layer is less than 50 % cemented/compacted and appears irregular
2
Discontinuous
The layer is 50 - 90 % cemented/compacted and appears regular
3
Continuous
The layer is more than 90 % cemented/compacted, and has few cracks only
3.13.3 Structure
The structure (or fabric) of the cemented/compacted layer may be described as:
Code
Class
Description
9
None
Massive without recognizable orientation
1
Platy
The cemented/compacted parts are plate-like with more or less horizontal
orientation
2
Vesicular
The layer has large, equidimensional voids which may be filled with
uncemented material
3
Pisolithic
The layer is composed of cemented, spherical nodules
4
Nodular
The layer is composed of cemented nodules or concretions of irregular
shape
3.13.4 Degree

Code
Class
Description
9
Non-cemented
and non-
compacted
No compaction/compaction is observed (slakes in water)
1
Compacted
Compacted soil material is harder or more brittle than non-compacted soil
material. Non-cemented.
2
Weakly
cemented
Cemented mass is brittle and hard, but can be broken in the hands
3
Moderately
cemented
Cemented mass cannot be broken in the hands but is discontinuous (less
than 90 % of soil mass)
4
Cemented
Cemented mass cannot be broken in the hands and is continuous (more
than 90 % of soil mass)
5
Indurated
Cemented mass cannot be broken by body weight (75 kg standard soil
scientist) (more than 90% of soil mass)

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3.14 Nodules and other mineral concentrations
(FAO, 2006)
Mineral nodules cover a large variety of secondary concentrations. There are gradual transitions
with mottles. Nodules are described according to their kind, type, abundance, size, shape, hardness
and colour, as well as their presence within the horizon:
3.14.1 Kind

Code
Class
Description
1
Crystal

2
Concretion
A discrete body with a concentric internal structure, generally
cemented
3
Soft segregation
Differs from the surrounding soil mass in colour and composition
but is not easily separated as a discrete body
4
Nodule
Discrete body without an internal organization
5
Pore infillings
Including pseudomycelium of carbonates and opal
6
Crack infillings

7
Residual rock fragment
Discrete body still showing rock structure
3.14.2 Type
Nodules are described according to their composition or impregnating substance. Examples:
Code
Description
1
Gypsum
2
Silica
3
Carbonates
4
Carbonates-silica
5
Salt
6
Clay
7
Clay-oxides
8
Manganese oxides
9
Iron-manganese oxides
10
Iron oxides
11
Sulphur
12
Not known
3.14.3 Abundance (by volume)

Code
Description
Class limits
9
None
0 %
1
Very few
0 - 2 %
2
Few
2 - 5 %
3
Common
5 - 15 %
4
Many
15 - 40 %
5
Abundant
40 - 80 %
6
Dominant
> 80 %
3.14.4 Size

Code
Description
Class limits
1
Very fine
< 2 mm
2
Fine
2 - 6 mm
3
Medium
6 - 20 mm
4
Coarse
> 20 mm

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3.14.5 Shape

Code
Description
1
Rounded (spherical)
2
Elongated
3
Flat
4
Irregular
5
Angular
3.14.6 Hardness

Code
Class
Description
1
Hard
Cannot be broken between the
fingers
2
Soft
Can be broken between
forefinger and thumb nail
3

Both hard and soft
3.14.7 Colour
General colour names are usually sufficient to describe nodules, in the same way as mottles:
Code
Description
1
White
2
Yellow
3
Yellowish red
4
Reddish yellow
5
Red
6
Yellowish brown
7
Reddish brown
8
Brown
9
Green
10
Blue
11
Bluish-black
12
Grey
13
Black
14
Multicoloured
3.15 Roots
3.15.1 Abundance
(FAO, 2006) (to be reported in *.PFH file)
Presence/absence of roots is the most essential information to take notice of. A qualitative
description of the size and the abundance of roots is important. Remember the abundance of roots
should only be compared within the same size class.
Abundance (number of roots/dm2) per size class:
Code
Size class
Very fine
<0.5 mm
Fine
0.5-2 mm
Medium
2-5 mm
Coarse
>5 mm
Abundance
9
None

0
0
0

0
1
Very few

1 - 20
1 - 20
1 - 2

1 - 2
2
Few

20 - 50
20 - 50
2 - 5

2 - 5
3
Common

50 - 200
50 - 200
5 - 20

5 - 20
4
Many

>200
>200
>20

>20

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3.15.2 Distribution
If there is a sudden change in the quantity and/or size of the roots it is very important to explain
why. Possible root limiting factors are: compaction (check the bulk density), cementations,
discontinuous pore system, etc. Sometimes it may be useful to record additional information, such
as an abrupt change in root orientation.
Code
Description
1
Continuous
2
in the space of cracks
3
in the space of vughs and channels
4
concentrated in nests
3.16 Other biological features
(FAO, 2006)
Krotovinas (an animal burrow which has been filled with material from another horizon), termite
burrows, insect nests, worm casts, burrows or other disturbances of larger animals are described in
terms of abundance and kind. In addition, specific locations, patterns, size, composition or any
other characteristic may be recorded.
3.16.1 Kind
Examples of biological features are the following:
Code
Description
1
Burrows (unspecified)
2
Open large burrows
3
Infilled large burrows
4
Earthworm channels
5
Termite or ant channels and nests
6
Other insect activity
7
Pedotubules3 (voids filled with soil
material by faunal and floral activity, for
further info read the footnote)
8
Charcoal
3.16.2 Abundance
Abundance of biological activity is recorded as a percentage of the exposed surface:
Code
Description
Class limits
1
Few

<5%
2
Common

5 - 15%
3
Many

15 - 40%
4
Abundant

> 40%

3 The term pedotubules is proposed for a group of pedological features which have a tubular external form
and which are distinguished from cutans by their complex internal composition and fabric. Pedotubules are
classified according to their internal fabric and composition, details of external form, distinctness, and by a
comparison of their fabric and composition with that of the horizons of the soil profile. Their general
morphology suggests their origin as voids caused by faunal and floral (root) activity which have been filled,
or partially filled, with soil material. Since little is known of the details of the effects of faunal activity on soil
materials, such interpretations are tentative (Brewer and Sleeman, 1963)

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3.16.3 Continuity
Abundance of biological activity is recorded as a percentage of the exposed surface:
Code
Description
1
Continuous
2
Discontinuous
3
Patchy
4
Locally
5
Other (explain)
3.17 Carbonates
(modified from FAO, 2006)
The presence of calcium carbonate (CaCO3) is indicated by adding some drops of 10% HCl to the
soil. Following information should be collected per horizon:
•
Is the matrix calcareous or non-calcareous (the exact quantity of carbonates will be tested in
the laboratory). If traces are found in at least one horizon of the profile, the presence/absence
should be recorded for all horizons.
•
Is the carbonate at least partly secondary (pedogenic).
3.17.1 Presence of carbonates
Following categories apply:
Code
Description
9
No presence of carbonates
1
Matrix is non-calcareous,
presence of secondary carbonate
2
Matrix is calcareous,
no evidences of secondary carbonate
3
Matrix is calcareous,
presence of secondary carbonates
3.17.2 Type of secondary carbonates
The type of secondary carbonates should be described. Following categories has been defined,
more can be defined where applicable:
Code
Description
1
Capping
2
Coatings
3
Nodules
4
Pendants
5
Pseudomycelia
6
Others (define)
3.18 Gypsum
(modified from FAO, 2006)
Gypsum (CaSO4•2H2O) may occur as residual, gypsous parent material or as newly formed features
such as pseudomycelia, coarse crystals (commonly as nests, beards or coatings, or as elongated
groups of fibrous crystals), or loose to compact powdery accumulations.

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Is gypsum present in the horizon? If so, where is it present (in the matrix, as nodules… …) and in
which form is it present (crystals, powder,…; primary or secondary etc.). If gypsum is present in the
soil, recommendations should be made for the laboratory on which samples the content of
gypsum should be measured. The presence/absence of gypsum is explained applying following
categories:
3.18.1 Abundance of gypsum

Code
Abundance (by volume)
9
0%
1
0 - 5%
2
5 - 15%
3
15 - 25%
4
25 - 60%
5
> 60%
3.18.2 Abundance of secondary gypsum

Code
Abundance (by volume)
0
0%
1
0 - 5%
2
> 5%
3.19 Readily soluble salts (modified from FAO, 2006)
Readily soluble salts are more soluble than gypsum; the most common salts are chlorides. The salt
content of the soil can be estimated from the electrical conductivity (EC in dS/m = mS/cm)
measured in a saturated soil paste or a more diluted suspension of soil/water.
If salts are observed during fieldwork, the electric conductivity of a saturated paste should be
analysed for all horizons in the soil.
Is salt present?
Y
Evidences of soluble salts
N
No evidences of soluble salts
X
Not known
3.20 Man-made materials
(simplified from FAO, 2006)
The areas dominated or significantly changed by human activity are rapidly extending, especially
in urban and mining areas. Of particular importance are the man-made materials found in soils;
their age, amount, state and composition determine their durability and environmental impact.
Any human impact on the soil should be recorded. Examples are:
•
Evidences of past agriculture
•
Presence of artefacts (e.g. ceramics)
•
Remains of past structures (e.g. postholes)
•
Other features of possible human origin (e.g. charcoal, brick fragments)

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3.21 Human-transported material (simplified from FAO, 2006)
This is any material brought onto the site. This may be for agricultural purposes (e.g. large-scale
terracing, mine spoil…), for human settlement, or simply to dispose of material (e.g. dredged
sediment). It is a soil parent material in the same way as alluvium.
3.22 Soil horizon designation
The term horizon indicates a soil layer presumed to bear the imprint of soil forming processes, as
opposed to layers that are laid down by sedimentation, volcanic activity or other geological events.
Horizons are identified by symbols that consist of one or two capital letters for the master horizon
and lower case letter suffixes for subordinate distinctions, with or without a figure suffix. The
detailed definitions of the different horizon symbols and rules that apply are found in Annex 7. This
annex also explains the use of symbols to express lithologic discontinuities and the vertical
subdivision when two horizons have the same set of master and subordinate symbols.
4 References
AG-Boden (2004). KA5: Bodenkundliche Kartieranleitung (5th edition). W. Eckelmann, H. Sponagel, W.
Grottenthaler, & K. J. Hartman. Schweizerbart, Hannover,

[http://www.schweizerbart.de/pubs/isbn/bgr/bodenkundl-3510959205-desc.html].
Brewer, R. and Sleeman, J.R. (1963). Pedotubules their definition, classification and interpretation. European
Journal of Soil Science 14 (1), 156–166.
Englisch, M., Katzensteiner, K., Jabiol, B., Zanella, A., de Waal, R. & Wresowar, M. 2005. An attempt to create a
[Forest Floor] Classification key for BioSoil. Lecture notes presented on the 1st Training Course on WRB
Soil Profile Description and Classification within the BioSoil Project. 3-7th October, 2005, Vienna.
FAO (1990). Guidelines for soil description (3rd edition). Soil Resources, Management and Conservation
Service. Land and Water Development Division, Food and Agricultural Organization of the United
Nations, Rome.
FAO. (2006). Guidelines for Soil Profile Description and Classification (4th edition) by R. Jahn, H.-P. Blume, V.B.
Asio, O. Spaargaren and P. Schad (Eds) and by R. Langohr, R. Brinkman, F.O. Nachtergaele and P.
Krasilnikov (Contributors), FAO, Rome.
FAO/ISRIC/ISSS, (1998). World Reference Base for Soil Resources. World Soil Resources Report, no. 84. FAO,
Rome.
Finke, P. Hartwich, R., Dudal, R., Ibàñez, J., Jamagne, M., King, D., Montanarella, L., Yassoglou, N. 2001.
Georeferenced soil database for Europe. Manual of Procedures. Version 1.1. Edited by European Soil
Bureau Scientific Committee, Research Report N°5. EUR 18092 EN.
IUSS Working Group WRB, 2015. World reference base for soil resources 2014, update 2015. World Soil
Resources Report No. 103. FAO, Rome.
Langohr, R. (1994). Directives and rationale for adequate and comprehensive field soil databases. In: New
waves in Soil Science. Refresher Course for Alumni of the International Training Centre for Post-
Graduate Soil Scientists of the Gent University, Harare 1994. ITC-Gent Publications series 5, 176-191.
Mikkelsen, J. Cools, N., Langohr, R. (2006). Guidelines for Forest Soil Profile Description, adapted for optimal
field observations within the framework of the EU Forest Focus Demonstration Project. BIOSOIL. Partly
based on the 4th edition of the Guidelines for Soil Profile Description and Classification (FAO, 2006).
Munsell, (2000). Munsell Soil Color Charts. Gretagmacbeth, New Windsor, NY, US.

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Ruhe, R.V. (1975). Geomorphology: geomorphic process and surficial geology. Houghton-Mefflin Co., Boston,
MA, US.
Schlichting, H., Blume, P. & Stahr, K. 1995. Bodenkundliches Praktikum (2nd edition). Blackwell Science, Berlin.
Schoeneberger P.J., D.A. Wysocki, E.C. Benham and W.D. Broderson (Eds.) (2002). Field book for describing
and sampling soils (version 2.0). Natural Resources Conservation Service, National Soil Survey Center,
Lincoln, NE, US.
SG-DBEM. (2003). Soil geographical Database for Eurasia & the Mediterranean: Instruction Guide for
Elaboration at scale 1:1,000,000 (version 4). J.J. Lambert, J. Daroussin, M. Eimberck, C. Le Bas, M.
Jamagne, D. King & L. Montanarella (Eds.). European Soil Bureau Research Report No. 8, EUR 20422 EN,
Office for Official Publications of the European Communities, Luxembourg.
Soil Survey Staff. (2003). Keys to Soil Taxonomy (9th edition). Natural Resources Conservation Service, United
States Department of Agriculture, Washington, D.C.
UN-ECE, (2004). United Nations Economic Commission for Europe: Convention on Long-Range
Transboundary Air Pollution. International Co-operative Programme on Assessment and Monitoring of
Air Pollution Effects on Forests. Manual on methods and criteria for harmonized sampling, assessment,
monitoring and analysis of the effects of air pollution on forests. 4th edition 1998, updated June, 2004
(http://www.icp-forests.org/Manual.htm).
WGS84. World Geodetic System 84. http://www.wgs84.com/

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Annex III – Recommendations for locating and describing a
soil profile
Location of the soil profile
The location of the soil profile should be as representative for the level plot as possible. Obviously
only surface characteristics can help us in this search. Factors of importance can be:
•
Composition of ground vegetation, e.g. if most of the experimental plot hosts no ground
vegetation do not locate the profile where vegetation is present
•
Composition of tree stand; dig the profile under the canopy of dominant tree species.
•
Avoid areas of strong human influence, such as ditches, earth banks, forest roads, tracks from
tree harvesting machines…
•
Avoid micro-lows and micro-highs, as they will allow more or less litter to accumulate, which
will have an influence on the biological activity and hydrology.
•
On experimental plots with steeper slopes, it is important to locate the profile as representative
as possible with respect to the general slope inclination. If the general slope is concave or
convex, then try to locate the profile at the level of the plot centre with respect to the slope
(meaning in the zone immediate outside the experimental plot to the left or the right of this
plot centre: not down- or upslope).
•
Other factors such as surface stoniness, rock outcrop, different land-use practice etc. should
also be taken into consideration so that the profile location is as representative as possible.
Orientation of the soil profile
Factors to take into consideration are:
•
If the slope inclination is such that it will have an important impact on the hydrology, then the
profile should be oriented with its long axe in the slope direction.
•
If the slope inclination is not important, the profile is oriented in such a way that by the time
the profile is to be studied the light should be equally distributed over the complete profile
wall (e.g. if you start to dig at 10 AM and you estimate that it takes 2h to dig the profile, and
30min to clean it for taking photos, then orient the profile towards SSW (180-200°). By the time
you can take photos the profile will have a perfect angle towards the sun. A wall that is partly
shaded partly with sunshine is impossible to describe optimally, and no quality photos can be
produced.
•
If the slope and light is not a problem, then other factors can help with the orientation of the
profile, such as microtopography, vegetation, etc. For example, if the experimental plot is
characterised by drainage ditches, orienting the profile with its long axis perpendicular to the
ditch will result in a profile where on the side walls it will be possible to observe the changes
from a wetter soil closest to the ditch towards a drier soil between the ditches.
Observations to be made while digging the profile
If the field work is organised in such a way that the person that will do the profile description will
be present when the profile is dug, it is advisable to make some first observations during this
process. Following aspects of a standard profile description can by substantially improved if
already considered during the profile digging, simply because the observations are made not only

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based on a two dimensional profile wall, but based on about one cubic metre of soil that is
removed:
•
The rock fragments: description of the abundance, size, shape, and type is considerable
improved, and special features such as presence/absence of pendants/cappings on the stones
are better observed.
•
Soil structure, especially type and degree of development
•
Cutanic features, especially if the quantity is low working in a three dimension will improve the
chance to observe such features
•
Presence of cementations and compactions will undoubtedly be discovered when the profile is
worked with the spade, shovel and pickaxe.
•
If carbonate is present, observing if at least part of the carbonate is secondary will be easier.
•
Quantification and size estimates of roots, as well as the total root depth is more accurately
observed
Observations in three dimensions
A standard profile is typically 80-100 cm wide, 180-200 cm long and should have a depth of 200
cm. The wideness and length can be reduced if e.g. the soil is very stony, but be careful not to
diminish the profile beyond the size where proper use of spade, showel, pickaxe is restricted. The
profile depth can be limited by a series of factors, such as:
•
The groundwater table. If the permeability of the soil is low, digging below the groundwater
table is possible and even soil sampling and/or making a few observations such as colour,
reductomorphic properties, … is possible. Remember to measure the actual groundwater
depth
•
Bedrock, either continuous or discontinuous rock that prevents further digging
•
Cementations of any kind, For example a Petrocalcic, Petroduric, Petrogypsic, Petroplinthic or
Pisoplinthic cemented horizon which makes any further digging impossible.
•
Parent material. If the C horizon material is reached at a shallower depth than 200 cm, further
digging can be stopped. It is though recommended to continue 20-50 cm to control that it
indeed is the C-horizon that has been reached.
When the profile in its full length has reach a depth of about 100-120 cm, further digging is
restricted to the 80-100 cm of the profile closest to the front wall. This creates a soil pit with 2 or
more steps.

After digging the profile, it is essential to clean the profile walls.
•
This is done by e.g. a knife, trowel, or another scraping tool with an metal blade, make sure that
the metal blade has rounded edges to avoid sharp scraping lines on the profile wall.
•
While the profile is cleaned, the soil is carefully observed, with respect to colours, presence
absence of roots, biogalleries, stones and other characteristics that might be important to
outline the horizons.
•
Take the first round of photos (see paragraph 3.2 of Annex 2): Of the profile, details of the
profile, and the surrounding landscape
•
Draw on the profile wall with the knife the horizon boundaries. The most important feature to
delineate horizons from each other is change of colour. Other feature that can be used to
differentiate genetic horizons from each other are a relatively sharp change over (vertical)

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distance of mottles, texture, coarse fragments, structure, porosity, cementation, compaction,
nodules, roots or carbonates.
•
A second round of photos ((see paragraph 3.2 of Annex 2) is taken of the profile with and
without the horizon boundaries indicated, and of particular details such as mottles, involutions,
biogalleries, disturbances etc.
If a soil is composed of well-developed relatively uniform horizons, focussing on the front wall for
the profile description is usually sufficient. If on the other hand the profile is more irregular and/or
the horizons are less developed, it might be necessary to study also the side walls. This should
appear from the profile description. For example the horizon depths in soil profiles located on a
strong slope should be measured perpendicular to the surface, which is easiest on the side wall.
For certain pedological features, it might be useful to study them on a horizontal surface. This is for
example possible while digging the profile, or when the first or second stair has been made at the
correct depth. If necessary, a new sub-profile is dug on the sidewall to the depth(s) where a
horizontal section is needed.

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Annex IV – Field equipment
Equipment for profile
description:
Number
Further information
Spade, pickaxe
1
Shovel
2
Bucket
1
Scraper
1
Make the corners rounded to avoid sharp lines on the cleaned
profile wall
Trowel
1
Sharpen the edges to allow a better cutting in the soil
Knife
1
The blade should be straight (e.g. to cut bulk density samples
straight) and as long as possible (recommended is 15-20 cm)
Field umbrella
1
To shade for sun and rain
Pruner or horticulture
sheer
1
To cut roots
Small painting brush
optional
To highlight certain special features e.g. slickensides, stones, etc.
Munsell Colour Chart
1
Try to avoid dirt on the colour chips
Folding ruler or measuring
tape
2
Two coloured ones are preferred
Note book
1
Large enough e.g. A5 format, with squared lines on the paper to
facility profile drawings
Writing pen/pencil
2
Marker pen
2
For sample labelling, black colours are more resistant to sun light
Sample labels
sufficient
Hand lens
1
Magnifications x10 (4 +6 or 2 + 8)
Soil thermometer
optional
Especially if the soil at or below 0°C
Penetration rod
1
Required if the soil is compacted, cemented or is stony
Clinometer or Abney-level
1
To measure slope inclinations
GPS system
1
Measuring coordinates of key points on the plot
Compass
1
For orientation of e.g. slope direction
Auger handle
1
Auger heads
selection
Selection in accordance to soil type, see table below
Extension rods
1
With one extension a depth of 225 cm can be reach
Photo camera and tripod
1
Water bottle
1
Water sprayer
1

For sampling
Number
Further information
Sampling tray
optional
Sample recipients
sufficient
Quality bags (plastic, cloth..) or boxes
Sample labels
sufficient
Sample frame
1 - 3
To sample the organic layer

For pF and BD
Number
Further information
Bulk density cylinders
(volume between 100 cm3
and 250 cm3) and lids
sufficient
Take care not to destroy the cutting edge of the ring while
inserting it into the soil
Ring holder
optional
Needed if the soil is hard (e.g. due to dryness and/or a high clay
content)
Impact free hammer
1
Eventually a geological hammer if fieldwork is done in
mountainous regions
Wood piece
1
To distribute the hammer impact equally
Hammering head
optional
For very hard soils, to be used with the guide cylinder
Cylinder guide
optional
Small iron saw
1
To cut the edges of the sampling rings

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Liquids:
Number
Further information
Distilled water*
±100 cl
To test moist colours; testing for water repellence
Concentrated H2O2*
±100 cl
Reacts to manganese (charcoal and organic matter not)
10% HCl*
±100 cl
Reacts to carbonates
α, α dipyridyl*
±100 cl
Reddish colour reaction if Fe2+ is present
Read also:
http://soils.usda.gov/use/hydric/ntchs/tech_notes/note8.html
* The liquids are by preference stored in bottles, which allow drop wise application (like eye drops). If this is
not possible, bring along plastic pipettes for careful application.

Soil augers:

Soil texture
Moisture
condition
Type of Edelman
augers
Riverside auger
Gouge auger

wet
Sand
-
-
Sandy
moist
Combi, sand
(+)
+

dry
Sand
-
(+)

wet
Combi
-
+
Loamy/silty
moist
Combi
-
+

dry
-
+
-

wet
Clay
-
+
Clayey
moist
Clay
-
+

dry
-
+
-

wet
Gravel
-
-
Stony
moist
Gravel
-
-

dry
-
+
-
Frozen soil

(Gravel)
(+)
-
"-" : not suitable
"(+)" : possibly suitable
"+" : suitable (recommended)
Clay-auger: thin blades, good for clayey and/ sticky soils when moist and wet
Combi-auger: all round auger best for medium textured soils when moist and wet
Sand-auger: has wide blades, so the sand stays in the auger even if the soil is relatively dry
Gravel-auger: with two cutting blades at the end that can drill and remove small stones
Riverside-auger: closed with drilling blades, the only auger that can be used in dry loamy or dry
clayey soils. It should be avoided when these soils are moist or wet! Sometimes also useful in frozen
soils
Gouge-auger: for non-stony soils preferentially moist or wet. It can take undisturbed samples.
Mode length variable, mostly 50 to 100 cm long.
For the sampling of the organic layer a frame of 25 by 25 cm is recommended, but alternatives with
a minimum total surface of 500 cm2 are acceptable. For mor humus, an auger with a diameter of 8
cm can be used.

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Annex V – Additional information on colour measurements
This annex provide additional information on the colours, particular for optimal measurements for
classification purposes (IUSS WG on WRB, 2015)
Colour should be determined, if possible, under uniform conditions out of direct sunlight. Early
morning and late evening readings are not accurate. Determination of colour has proven to be
often inconsistent between individuals or, even for the same person. Since colour is significant with
respect to many soil properties and for soil classification, routine cross-checks are recommended.
To save time in the field and to improve the colour measurements, it is recommended to measure
the colours in the laboratory. Let fragments of the soil air-dry before the dry colours are measured,
then gently add vaporised water to moisten the sample to field capacity. The wet colour can be
measured after saturation of the sample with water. Colours for waterlogged soils should be
measured immediately before the soil gets oxidised.
For all horizons, at least the moist colours should be recorded (if the soil is arid or wet, respectively
dry and wet colours may replace the moist ones). In those soils where one or more diagnostic
horizons or properties might be present, additional colours are mandatory as summarised in the
table. For example, for a soil with a spodic horizon (diagnostic for Podzols), information on the
moist crushed colour is required according to the WRB.
Table 4: Required colour measurements
Soil
moisture
condition
Measured
colour
Horizons for which colours are required
O, H
A
E
B
C
Dry
Matrix
(broken)

2a, 2b
4
5
3

Crushed

2a, 2b

Moist
Matrix
(broken)
1
1, 2a, 2b
1
1
1

Crushed

2a, 2b
6

Wet
Matrix
1b
1b
1b
1b
1b
1 Moist colours should always be recorded for all horizons in the profile, except for those soils that
1b) naturally are wet (e.g. Gleysols, Histosols). For those soils, the wet colours are measured instead
of moist colours. The matrix colour can be considered the same as the broken colour.
2a Broken colours are mandatory to record if the soil has a dark topsoil with colours of 3.5/3.5
(value/chroma) or less when moist, and a value of 5.5 or darker when dry.
2b If the soil may have aridic properties (relative low organic carbon content, evidences of aeolian
activity, high base saturation…) these colour measurements are required too.
3 Should be measured if the topsoil has colours of 3.5/3.5 (value/chroma) or less when moist, and a
value of 5.5 or darker when dry (see 2a). If no C-horizon is present, the colour should be measured
for the horizon immediately underlying the surface horizon(s).
4 If the eluvial horizon has a colour value of 4 or more and a chroma of 4 or less, then measure also
the dry colour.
5 If the moist colour is redder than 5YR (3.5YR or redder) then also the dry colour should be
measured (required for the rhodic qualifier).
6 If the soil may have a spodic horizon (required for Podzols), then the crushed colour is mandatory
to record. The colour required for a spodic horizon (moist) is 10YR or redder with value of 3 or less
and chroma of 2 or less. If the colour is 7.5YR or redder the value required is 5 or less and the
chroma 4 or less.

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Annex VI – Guidelines for field estimates of textural classes
The textural class can be estimated in the field by feel. For this, the soil sample must be moist (as
close as possible but not exceeding the field capacity). Fragments >2 mm must be removed.

Clay
Soil can be rubbed, is sticky, can be moulded but is stiff (high plasticity), smeared surface is shiny
Silt
Soil can be rubbed, is non-sticky, and feels floury (like talc)
Sand
Cannot be moulded, does not soil fingers and feels gritty
Key to the soil texture classes (adapted from Schlichting et al., 1995)
y
Cannot be rolled into a ball

% clay

• Not dirty, not floury, no fine material adhering to fingers: sand
S
<5

• If grain sizes are mixed: Unsorted sand
US
<5

• If most grains are very coarse (>0.5 mm): very coarse and coarse sand
CS
<5

• If most grains are of medium size (0.25-0.5 mm): medium sand
MS
<5

• If most grains are of fine size (<0.25 mm) but still grainy: fine sand
FS
<5

• If most grains are of very fine size (<0.1 mm), almost floury: very fine sand
VFS
<5
2
Can be rolled into a ball but not into a wire

• Not floury, grainy, scarcely any fine material sticking to fingers, forms a ball
weakly, adheres slightly to the fingers: loamy sand
LS
<12

• As 2.1 but floury: sandy loam
SL
<10
3
Can be rolled into a wire of about 3 to 7 mm in diameter (about half the
diameter of a pencil) but breaks when trying to bend into a ring, sticks to
the fingers

Floury and not cohesive

• Some grains to feel: silt loam
SiL
<10

• Floury and not cohesive, no grains to feel: silt
Si
<12

Cohesive, sticks to the fingers, has a rough and smeared surface after squeezing
between fingers

• Is very grainy and not sticky: sandy loam
SL
10-25

• Neutral feel, neither sticky, nor gritty, nor floury: loam
L
8-27

• Is not grainy but distinctly floury and somewhat sticky: silt loam
SiL
10-27

• Is very grainy and not sticky: sandy loam
SL
10-25

• Sticky and grainy to very grainy: sandy clay loam
SCL
20-35
4
Can be rolled into a wire smaller than 3 mm in diameter (less than half of
that of a pencil) and bent to form a ring of about 2-3 cm in diameter,
cohesive, sticky, shiny smeared surface

• Very grainy: sandy clay
SC
35-55

• Grains can be seen and felt: clay loam
CL
25-40

• No grains to see and to feel, low plasticity: silty clay loam
SiCL
25-40

• No grains to see and to feel, high plasticity: silty clay
SiC
40-60
5
Shiny smeared surface and high plasticity

• Some grains to see or to feel, grates between teeth: clay
C
40-60

• No grains to see or to feel, does not grate between teeth: heavy clay
HC
>60

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Annex VII – Detailed definitions, rules and conventions on
master and subordinate horizon symbols
1 Vocabulary
Organic material (OM) (IUSS Working Group WRB, 2007) (from Greek organon, tool) consists of a
large amount of organic debris that accumulates at the surface under either wet or dry conditions
and in which the mineral component does not significantly influence the soil properties.
Diagnostic criteria. Organic soil material must have one of the two following:
(1) 20 percent or more organic carbon (by mass) in the fine earth; or
(2) if saturated with water for 30 consecutive days or more in most years (unless drained), one or
both of the following:
(a) (12 + [clay percentage of the mineral fraction * 0.1] percent or more organic carbon in

the fine earth (by mass), or

(b) 18 percent or more organic carbon (by mass) in the fine earth.

Organic horizons
The organic horizons (codes: OL, OF, OH) are formed by dead organic matter (OM), mainly leaves,
needles, twigs, roots and, under certain circumstances, materials such as mosses and lichens. This
OM can mainly be transformed in animal faeces. An organic horizon contains 20 % or more organic
carbon (by mass) in dry samples, without living roots.
Hemorganic horizons
The hemorganic horizons (code: A) are formed near the soil surface, generally beneath the organic
horizons. Coloured by organic matter, these horizons are generally darker than the underlying
mineral part of the soil profile. It is generally accepted that in the soil fraction < 2mm of the A
horizon, the organic carbon has to be less than 20% by mass (following WRB, FAO 2006, Broll et al.
2006).
Recognisable remains
Recognisable remains within an organic or hemorganic horizon are organic materials like leaves,
needles, roots, bark, twigs and wood, fragmented or not, whose original organs are recognizable
by the naked eye or with a 5-10 X magnifying hand lens. Fresh litter generally consists for 100% of
recognizable remains (Zanella et al. 2010)
Humic components
Humic components of an organic or hemorganic horizon are small particles of organic remains
and/or grains of organic or organo-mineral matter mostly comprised of animal droppings of
different sizes. The original organs which compose the litter and generate the small particles (free
or incorporated in animal faeces) are not recognizable by the naked eye or with a 5-10 X
magnifying hand lens. Bound mineral particles can be visible within the mass.

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Well decomposed organic substrate generally consists for 100% out of humic components.
However, the generated humic component can also be in the hemorganic (A) and organic (OL, OF,
OH) horizons. Thus, an A horizon made of anecic and endogeic earthworm hemorganic faeces as
well as a totally, finely decomposed and mostly organic OH horizon resulting from enchytreid and
microarthropod activities, can both be composed for 100% of humic components, despite
differences in the animals responsible for the structure of the horizons (Zanella et al. 2010).
Fibric component
Non-decomposed or very weakly decomposed hygrophilous plant remains like sphagnum species,
sedges, rushes, reeds... Whole plants, parts of them and/or free plant organs (leaves, needles, twigs,
wood, roots...) sometimes lying in more or less dark coloured layers.
Sapric component
Homogeneous dark organic and organo-mineral matter comprised of well decomposed plant
remains partly mixed with mineral particles. Plant structures are not visible to the naked eye or with
a 5-10 X magnifying hand lens. Animal droppings are possible in periodically drained horizons and
can be abundant in drained peats.
Mineral components
Mineral components of an organic or hemorganic horizon are mineral particles of different sizes,
free or very weakly bound to humic components and visible by the naked eye or with a 5-10 X
magnifying hand lens.
Zoogenic transformed material
Zoogenic transformed materials are recognizable remains and humic components processed by
animals (i.e. leaves, needles and other plant residues more or less degraded by soil animals, mixed
with animal droppings. A fine, powdered and/or grained structure (less than 1 mm) is typical in a
terminal stage of faunal attack in an organic horizon. At this last level of biotransformation, the
substrate (OH horizon) is essentially comprised of organic animal droppings of varying size
(droppings of epigeic earthworms, macro-arthropods such as millipedes, woodlice and insect
larvae, micro-arthropods such as mites and springtails and enchytraeids dominate). Within
hemorganic horizons, animal activity leads to different types of A horizons, depending on the
animals’ ability to dig into the mineral soil and thoroughly mix organic and mineral matter.
Non zoogenic transformed material
Non zoogenic transformed materials are recognizable remains and humic component processed
by fungi or other non-faunal processes (i.e. leaves, needles and other plant residues more or less
fragmented and transformed into fibrous matter by fungi. Recognizable and recent animal
droppings are absent or not detectable by the naked eye in the organic horizons; fungal hyphae
can be recognized as white, brown or yellow strands permeating the organic or hemorganic
substrates; traces of animal activity (old bite marks, mucus) may sometimes be detectable but are
always marginal. In the last stage of biodegradation of an organic horizon, non zoogenic substance
may essentially be composed of brown, dry plant residues more or less in powder form or tiny
fragments (OF and OH horizons), or be massive like a dark wet plastic clay (OH or very organic A
horizons).
By the naked eye or with a 5-10 X magnifying hand lens, each topsoil horizon appears to be
composed of recognizable remains, humic and mineral components (fig. 1). At the soil surface, the
animals or plant cover shed litter (remains) on and within the soil. Animal remains exist too, but
they are quite negligible compared to plant remains and often overlooked by the neophyte. Litter
is made up of recognizable residues and humic components (because of soil biological activity). In

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the other direction, the geological substrate “leaks” fragments of rock, which in the topsoil become
mineral (free grains) and humic (grains incorporated in faeces) components. The mineral
component can also be increased by surface erosion. The process perceived by the naked eye
hides a more complex world of chemical-physical–biological processes. In unfavourable conditions
for soil fauna the process is mainly dominated by fungi. Therefore, the new definitions of zoogenic
and non zoogenic transformed material have been coined to distinguish zoogenic biological
transformation from mycogenic transformation. The aim of a naked eye examination is to collect
initial data and information for the purposes of a more detailed research on the same system. The
vocabulary terms have been selected with regards to a dynamic interpretation of current
knowledge on the topsoil.
2 Soil horizon designation
2.1 Master horizons and layers
2.1.1
The Organic horizons
2.1.1.1 O horizon or layer
The O horizon or layer is dominated by organic material, consisting of fresh, partially or completely
decomposed litter (such as leaves, needles, twigs, mosses, and lichens) that has accumulated on
the surface; it may be on top of either mineral or organic soil. It is not saturated with water for
prolonged periods. The mineral fraction of such material is only a small part of the volume of the
material and generally is much less than half of the mass.
An O layer may be at the surface of a mineral soil or at any depth beneath the surface if it is buried.
However, a horizon formed by illuviation of organic material into mineral subsoil is not an O
horizon (FAO, 2006).
A subdivision of the organic O-layers is made according to the following definitions (Zanella et al.
2010):
OL-horizon (Litter, Förna): this organic horizon is characterised by an accumulation of mainly
leaves/needles, twigs and woody materials (including bark), fruits etc.
This sublayer is generally indicated as litter (Klinka et al., 1981, Green et al., 1993, Jabiol et al., 1995,
Delecour, 1980). It must be recognized that, while the litter is essentially unaltered, it is in some
stage of decomposition from the moment it hits the floor and therefore it should be considered as
part of the humus layer.
There may be some fragmentation, but the plant species can still be identified. So most of the
original biomass structures are easily discernible. Leaves and/or needles may be discoloured and
slightly fragmented. The humic components amounts to less than 10 % by volume; recognisable
remains 10% and more, up to 100% in non-decomposed litter.
OL types (suffixes: n, v, t)
•
OLn: new litter (age < 1 year), neither fragmented nor transformed/discoloured leaves and/or
needles;
•
OLv: old litter (aged more than 1 year, vetust, verändert, verbleicht), slightly altered,
discoloured, bleached, softened up, glued, matted, skeletonized, sometimes only slightly
fragmented leaves and/or needles.

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•
OLt: transitional (t) litter made of leaf petioles, twigs, bark and surface cast accumulation in very
active mull forms (eumull generally in mixed hardwood forest – described in ash/beech
stands).
Note: The passage from OLn to OLv can be very rapid (1 to 3 months) or very slow (more than a
year) according to types of litter (plant species composition), climate, season and level of soil
biological activity
OF-horizon (fragmented and/or altered) is a zone immediately below the litter layer. This organic
horizon is characterised by an accumulation of partly decomposed (i.e. fragmented, bleached,
spotted) organic matter derived mainly from leaves/needles, twigs and woody materials. The
material is sufficiently well preserved to permit identification as being of plant origin (no
identification of plant species).The proportion of humic components is between 10 % and 70 % by
volume. Depending on humus form, decomposition is mainly accomplished by soil fauna (OFzo) or
cellulose-lignin decomposing fungi (OFnoz). Slow decomposition is characterised by a partly
decomposed matted layer, permeated by hyphae.
Note: this is the fragmented layer in non-saturated soils (Klinka et al., 1981, Green et al., 1993,
Jabiol et al., 1995, Delecour, 1980)
OF types (suffixes: zo, noz)
OFzo = content in zoogenic transformed material > 10% of the volume of the horizon;
OFnoz = content in non-zoogenic transformed material 90% or more of the volume of the horizon;
OH-horizon (humus, humification): characterised by an accumulation of dark, well-decomposed,
amorphous organic matter. It is partially coprogenic, whereas the F horizon has not yet passed
through the bodies of soil fauna. The humified H horizon is often not recognized as such because it
can have friable crumb structure and may contain considerable amounts of mineral materials. It is
therefore often misinterpreted and designated as the Ah horizon of the mineral soil and not as part
of the forest floor as such. To qualify as organic horizon, it should fulfil the FAO requirement, as
described above. The original structures and materials are not discernible. Humic components
amounts to more than 70 % by volume. The OH is either sharply delineated from the mineral soil
where humification is dependent on fungal activity (mor) or partly incorporated into the mineral
soil (moder).
Note: This horizon coincides with what is called the humus layer (Klinka et al., 1981, Green et al.,
1993, Jabiol et al., 1995, Delecour, 1980)
OH types (suffixes: zo, noz, r, f)
•
OHzo = content in zoogenic transformed material > 30% of the volume of the horizon;
•
OHnoz = content in non-zoogenic transformed material 70% or more of the volume of the
horizon;
Concerning the organic layers, a distinction is made between the water saturated organic layers,
designated as ‘H’, and the aerated organic materials indicated as ‘O’.
2.1.1.2 H horizon or layer
The H horizon or layer is dominated by organic material, formed from accumulations of fresh or
partially decomposed organic material at the soil surface (which may be under water). All H
horizons are saturated with water for prolonged periods or were once saturated but are now
drained. A H horizon may be on top of mineral soils or at any depth beneath the surface if it is
buried (FAO, 2006).

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Distinction of subhorizons in the organic H-layers (Zanella et al., 2010):
Hf (from Histic and fibric) horizon
Histic organic horizon consisting almost entirely of almost unchanged plant remains. Fibric
component ≥ 90%, sapric component < 10% of horizon volume. Content of rubbed fibres ≥ 40% of
soil by dry weight (105 °C)4. Von Post scale of decomposition: 1 to 3 (4, 5 possible)5.
Remarks: Plant remains from mosses like Sphagnum species, sedges, rushes and reeds are
recognizable. Fibric horizons are quite common in bogs and oligotrophic parts of isolated fens.
These horizons are mainly composed of remains of Sphagnum and Eriophorum species. In
mesotrophic fens, the Hf-horizon is mainly composed of remains of sedges and rushes. Fibric
horizons in eutrophic fens are less common because of the fast decomposition in those
environments. A further differentiation could be made on the base of the origin of the plant
material (oligotrophic mosses, mesotrophic sedges, mesotrophic sedges and reeds).This could be
adapted to national, regional and local circumstances.
Note: this horizon coincides with what is classified as fibric (Klinka et al., 1981, Green et al., 1993) or
fibrist (Delecour, 1980).
Hfs (from Histic, between fibric and sapric)
Histic organic horizon consisting of half decomposed organic material not fitting the definition of
fibric (Hf) or sapric (Hs). Fibric component 10% to 70%, sapric component 90% to 30% by volume
(Figure 9). Content of rubbed fibres 10 to 40% of soil by dry weight (soil dried at 105 °C), Von Post
scale of decomposition: 4 to 7 (8 possible)6.
Note: This horizon coincides with what is classified as mesic (Klinka et al., 1981, Green et al., 1993)
or hemist layer in saturated soils;
Hs (from Histic and sapric)
Histic organic horizon in advanced stage of decomposition. Sapric content ≥ 70% of the horizon
volume; fibric component less than 30% (Figure 9). Content of rubbed fibres < 10% of soil by dry
weight (soil dried at 105 °C). Von Post scale of decomposition: 8 to 107.

4 The content (by mass) of the total organic fraction is generally more than 80%. When saturated, this fibric
horizon can have a water content of far more than 850% of the oven-dry weight (Soil Taxonomy 1975).
5 von Post scale: (1) Undecomposed; plant structure unaltered; yields only clear water coloured light yellow
brown; (2) almost undecomposed; plant structure distinct; yields only clear water coloured light yellow
brown; (3) very weakly decomposed; plant structure distinct; yields distinctly turbid brown water, no peat
substance passes between the fingers, residue not mushy.
6 von Post scale: (4) weakly decomposed; plant structure distinct; yields strongly turbid water, no peat
substance escapes between the fingers, residue rather mushy; (5) Moderately decomposed; plant structure
evident, but becoming indistinct; yields much turbid brown water, some peat escapes between the fingers,
residue very mushy; (6) strongly decomposed; plant structure somewhat indistinct, but more evident in the
squeezed residue than in the undisturbed peat; about one-third of the peat escapes between the fingers,
residue strongly mushy; (7) Strongly decomposed; plant structure indistinct, but recognizable; about one-
half of the peat escapes between the fingers.
7 von Post scale: (8) very strongly decomposed; plant structure very indistinct; about two-thirds of the peat
escapes between the fingers, residue almost entirely resistant remnants such as root fibres and wood; (9)
Almost completely decomposed; plant structure almost unrecognizable; nearly all the peat escapes between
the fingers; (10) Completely decomposed; plant structure unrecognizable; all the peat escapes between the
fingers.

Samplin

Version 0
Remarks
fraction
structure
and soil
Note: Th
or sapri
The follo
Hszo =
earthwo
semiterr
The min
Hsnoz =
ponds.
oligotro
nutrient
Hsl = H
fraction
bioactiv
2.1.2
2.1.2.1 T
A miner
structure
followin
•
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05/2016
s: Sapric hor
than those
e, pH, nutrie
organisms.
his horizon c
st (Delecour
owing three
Meso or m
orms. The m
restrial hum
eral fraction
= Massive Hs
Humificatio
phic enviro
ts and bases
Hs horizon w
is more th
ity is compa
The miner
The A horiz
al horizon fo
e of the pa
g:
accumulatio
displaying p
perties result
ysis of Soil
rizons of bro
in fens or b
ent content
oincides wit
r, 1980).
horizons ca
macrostructu
mineral frac
us forms (bo
n (clay, loam
s horizon w
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tion is less
oth naturally
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the activit
of humic su
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ster horizon
below an O
obliterated
matter intim
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asturing, or s
around wel
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e to differen
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a high acti
(Figure 10
ally drained
nly high com
animals. Com
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particles (c
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horizon, in w
d and charac
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rizons (see b
similar kinds
ls have mos
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ka et al., 198
horizon:
ivity of soil
). Typically
). Activity of
mpared to th
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re acid and
ineral fractio
clay, silt and
in the form

rs
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Part X
Page 157
r mineral
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al., 1993)
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•
A morphology that is different from the underlying B or C horizon, resulting from processes
related to its surface position.
If a surface horizon has properties of both A and E horizons but the dominant feature is an
accumulation of humified organic matter, it is designated an A horizon.
Where the climate is warm and arid, the undisturbed surface horizon may be less dark than the
underlying horizon and contains only small amounts of organic matter. It has a morphology
distinct from the C layer, though the mineral fraction may be unaltered or only slightly altered by
weathering; such a horizon is designated A because it is at the surface. Examples of surface
horizons which may have a different structure or morphology due to surface processes are
Vertisols, soils in pans or playas with little vegetation, and soils in deserts.
Recent alluvial, colluvial or aeolian deposits that retain fine stratification are not considered to be
an A horizon unless cultivated.
The different diagnostic A horizons are identified in the field observing the soil mass by the naked
eye or with 5-10X magnifying hand lens, assessing the structure (Soil Survey Manual (1993) and
FAO Guidelines 2006) and consistence, and measuring the acidity (pHwater).
Zanella et al. (2010) distinguishes the following five diagnostic A horizons:
maA: biomacrostructured A horizon = A aneci-endovermic
General characteristic: mixed biogenic organo-mineral peds dominate
Diagnostic criteria:
To be identified as a biomacrostructured A horizon, a layer must have at least four of the following:
•
structure grade, observable in place in undisturbed soil: never weak, never lack of structure;
•
presence of peds, observable in place in undisturbed soil as well as in the palm of the hand
after applying a weak-moderate pressure on a sample of soil: all sizes of peds are present, but
the volume of peds larger than 4 mm is greater than the volume of all other peds or units of
soil;
•
structure (FAO and USDA) - grade: moderate or strong; size if granular shape: medium (2-5 mm)
and/or coarser; size if subangular blocky shape: fine (5-10 mm) or fine (5-10 mm) and very fine
(< 5 mm);
•
living earthworms, or earthworm galleries and/or casts;
•
earthworm galleries within underlying horizon;
•
pH in water >5.
Origin:
Biological: the whole horizon is made of anecic and endogeic earthworm faeces (the limit of 4 mm
is rarely reached by droppings of arthropods and epigeic earthworms); roots and fungal hyphae
(visible or not) also play an important role in the formation and stability of aggregates. Living
earthworms or their galleries and casts are always present within the horizon.
meA: biomesotructured A horizon = A endo-epivermic
General characteristic: composed of coloured organic (dark) or/and organo-mineral biogenic peds

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Diagnostic criteria:
The biomesotructured A horizon has all the following properties:
•
structure grade, observable in place in undisturbed soil: never weak, never lack of structure;
•
presence of peds, observable in place in undisturbed soil as well as in the palm of the hand
after applying weak pressure on a sample of soil: all sizes of peds are present, but the volume
of the peds larger than 1 mm and smaller than 4 mm is greater than the volume of all the other
peds or parts of soil;
•
structure (FAO and USDA) - grade: moderate or strong (rarely weak); size if granular shape: fine
(1-2 mm) and/or medium (2-5 mm); size if subangular blocky shape: very fine (<5 mm).
•
living earthworms, arthropods or enchytraeids or their droppings.
Origin:
Biological: earthworms (mostly epigeic and small endogeic), enchytraeids and arthropods are
responsible for the structure; roots and fungal hyphae are also involved. Anecic and large endogeic
earthworm droppings, classified typically as biomacro peds, are generally larger than 4 mm.
NB.: Green et al. (1993) described a rhizomull characterized by an A horizon which could be a
biomesostructured A horizon. In this case, the thick mat of fine roots of grasses plays a major role in
determining the type of structure of the topsoil.
miA: biomicrostructured A horizon = A enchy-arthropodic
General characteristic: composed of fine mineral grains mixed with fine organic particles and dark-
coloured biogenic peds (holorganic or hemiorganic)
Diagnostic criteria:
The biomicrostructured A horizon has at least five of the following properties:
•
absence of peds > 4 mm; observable both in situ, in undisturbed soil, and in the palm of the
hand after applying a slight pressure on a sample of soil: peds of varying size can be present,
but the volume of peds smaller than 1 mm is greater than the volume of all other peds or
parts of the soil; gently squeezing the soil, almost all large peds easily reduce into smaller
units;
•
structure (FAO and USDA) - grade: moderate, strong; shape: granular; size: very fine (< 1 mm);
•
presence of (generally uncoated) mineral grains (mineral component > 10%);
•
> 10% organic particles and dark-coloured biogenic peds (holorganic or hemiorganic = humic
component)
•
living arthropods, enchytraeids or their droppings;
•
pH in water <5.
Origin:
Biological: the horizon has an important amount of faecal pellets, droppings of enchytraeids
(potworms) (larval stages, insects, spiders, mites, springtails…), micro-arthropods and particles of
organic matter (remains of decomposed litter). Hyphae and roots are also very common.

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Field identification:
•
Take a sample of A horizon rich organic soil material. If squeezed gently in the palm of the
hand, the sample breaks up into units composed of organic and organo-mineral peds (single or
bound droppings, droppings bound to mineral grains), organic particles and mineral grains.
Observing the soil with a magnifying hand lens (5-10X) reveals a lot of complex holorganic and
hemorganic peds. Their mean size is less than 1 mm but the structure of the soil is clearly
expressed and never weak or absent. The appearance can be very similar to that of the OH
horizon.
•
Observed on sandy or loamy substrate (acid or non-calcareous). The large amount of quartz
grains (> 50%) seems to prevent the formation of a larger size structure or a massive one.
sgA: single grain A horizon
General characteristic: single grained structure, biological aggregation absent or involving less than
5% of the soil volume
Diagnostic criteria:
To be identified as a single grain A horizon, a layer must have at least four of the following:
•
an unbound loose consistence (undisturbed soil mass);
•
structure (FAO and USDA): single grain;
•
presence of clean (= uncoated) mineral grains;
•
<10% of fine organic particles and/or dark-coloured biogenic (holorganic or hemorganic) peds;
•
pH in water < 5.
Origin: Mineral grains coated with organic matter indicate a process of podzolisation in places.
Faecal pellets of micro-arthropods or enchytraeids are sometimes present but irrelevant (< 10%).
Field identification for structure and consistency:
In undisturbed soil - Structure: single grain. Sub-units of soil do not appear bound together or are
weakly bound in a casual manner. Sometimes, in a relatively organic sample, very small peds (< 1
mm) are detectable in the mass (animal pellets), because of their dark colour and organic
composition in a light mineral mass. At other times the horizon looks like a brownish-red coloured
nearly uniform fluffy mass. In this case, it is very difficult to separate mineral from scarcely present
organic components.
In a sample of soil in the palm of the hand - When squeezing gently with the fingers, the sample
breaks up progressively into large then fine, artificial units. The fine units are mostly mineral, more
or less coloured by organic matter in coatings. Animal pellets are absent or in traces (less than
10%). The sample could be wrongly classified as weak medium granular structured but grains,
never zoogenic, break easily into micro units because they are very weakly attached together in
variable manner and size (no apparent soil structure).
Horizon designation: Because of observable processes of eluviation or podzolisation, the horizon
could be classified as EA (or E) or AB following its similarity to mineral horizons.
msA: massive A horizon
General characteristic: massive structure, biological aggregation absent or involving less than 5% of
the soil volume

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Diagnostic criteria:
To be identified as a massive A horizon, a layer must have at least three of the following:
•
heterogeneous but one-piece matrix;
•
structure (FAO and USDA): massive;
•
presence of clean (= uncoated) mineral grains;
•
pH in water < 5.
Origin: Presence of mineral grains coloured by organic matter in coatings. Cohesion forces among
parts of soil seem equally distributed in the soil, as they depend mostly on physical or chemical
conditions rather than biological aggregation (peds originated by animals < 5%). Past biological
activity (incorporation of organic matter) could also be involved in the process of formation of the
horizon, but traces of current biological activity are never visible. Organic or hemorganic pellets of
microarthropods or enchytraeids are present (< 5% of the soil volume). A 5-10 X magnifying hand
lens is necessary to detect the composition of the pellets or grains, the size of the most common
biostructured units being less than 1 mm.
Field identification for structure and consistency:
In undisturbed soil - Structure: massive. The units of soil are bound together in a relatively compact
manner. No planes or zones of weakness are detectable in the mass, which appears as a
heterogeneous coloured layer of organo-mineral soil.
If the soil is dry, when applying a moderate to strong pressure with the fingers, the soil sample
progressively breaks up into finer artificial units. These fine units have a varying composition:
mineral, organo-mineral and organic. If the soil is moist, the shape of the sample can be modified
as in a tender, plastic, non-elastic matter.
Horizon designation: Because of observable processes of eluviation or initial podzolisation, the
horizon could be classified as AE (or EA), following its resemblance to a mineral E horizon.
Zoogenic and non-zoogenic A horizon
Azo = zoogenic A horizon.
Azo = maA (implied maAzo) or meA (meAzo) or miA (miAzo).
Anoz = A horizon considered as non-zoogenic. To the naked eye, or with the help of a hand lens,
this horizon does not show relevant (mass) signs of animal activity (absence of galleries; droppings,
mucus, animal remains etc., < 5% of the soil volume). Zoological agents are not involved in the soil
aggregation. Fungal structures can be visible.
Anoz = sgA (implied sgAnoz) or msA (msAnoz).

2.1.2.2 E horizon
A mineral horizon in which the main feature is loss of silicate clay, iron, aluminium, or some
combination of these, leaving a concentration of sand and silt particles, and in which all or much of
the original structure of the parent material has been obliterated.
An E horizon is usually, but not necessarily, lighter in colour than an underlying B horizon. In some
soils, the colour is that of the sand and silt particles but, in many soils, coatings of iron oxides or
other compounds mask the colour of the primary particles. An E horizon is most commonly
differentiated from an underlying B horizon in the same soil profile by colour of higher value or

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lower chroma, or both; by coarser texture; or by a combination of these properties. An E horizon is
commonly near the surface, below an O or A horizon and above a B horizon, but the symbol E may
be used without regard to position in the profile for any horizon that meets the requirements and
that has resulted from soil processes.
2.1.2.3 B horizon:
A horizon formed below an A, E, H or O horizon, and in which the dominant features are the
obliteration of all or much of the original structure of the parent material, together with one or a
combination of the following:
•
Illuvial concentration of clay, iron, aluminium, humus, carbonates, gypsum, silica or some
combination of these;
•
Evidence of removal of carbonates;
•
Residual concentration of iron and aluminium oxides;
•
Coatings of humus and/or oxides that make the horizon conspicuously lower in value, higher in
chroma, or redder in hue than overlying and underlying horizons;
•
Alteration that forms silicate clay or liberates oxides or both, and that forms a granular, blocky,
or prismatic structure if volume changes accompany changes in moisture content;
•
Brittle consistence.
All kinds of B horizons are, or were originally, subsurface horizons. Included as B horizons are layers
of illuvial concentration of carbonates, gypsum, or silica (these horizons may or may not be
cemented) and brittle horizons that have other evidence of alteration, such as prismatic structure
or illuvial accumulation of clay.
Examples of layers that are not B horizons are layers in which clay films either coat rock fragments
or are on finely stratified unconsolidated sediments, whether the films were formed in place or by
illuviation; layers into which carbonates have been illuviated but that are not contiguous with an
overlying pedogenetic horizon; and layers with gley colours but no other pedogenetic changes.
2.1.2.4 C horizon
A horizon, excluding hard bedrock, that is little affected by pedogenetic processes (lacks properties
of H, O, A, E, or B horizon). The material of C layers may be either like or unlike that from which the
soil is presumed to have formed. A C layer may have been modified even if there is no evidence of
pedogenesis. Plant roots can penetrate C layers, which provide an important growing medium.
Included as C layers are sediments, saprolite, and unlithified geological materials that, commonly,
slake within 24 hours when air-dry chunks are placed in water and, when moist, can be dug with a
spade. Some soils form in material that is already highly weathered; such material that does not
meet the requirements of A, E or B horizons is designated C. Changes not considered pedogenetic
are those not related to overlying horizons. Layers having accumulations of silica, carbonates, or
gypsum, even if indurated, may be included in C layers, unless the layer is obviously affected by
pedogenetic processes; then it is a B horizon.
2.1.2.5 R layer
Hard bedrock underlying the soil. Granite, basalt, quartzite and indurated limestone or sandstone
are examples of bedrock that are designated R. Air-dry or drier bits of an R layer, when placed in
water, will not slake within 24 hours and are resistant to pressure with the fingers. The R layer is
sufficiently coherent when moist to make digging with a spade impractical, although it may be
chipped or scraped. Some R layers can be ripped with heavy power equipment. The bedrock may
be fissured, but few roots can penetrate. The cracks may be coated or filled with clay or other
material.

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2.1.2.6 I layer:
Ice lenses and wedges that contain at least 75% ice (by volume) and that distinctly separate
organic or mineral layers in the soil.
In areas affected by permafrost, ice bodies may form lenses of wedges that separate entire soil
layers. Where such ice concentrations occur within the depth of soil description, they can be
designated as I layer.
2.2 Transitional horizons
There are two kinds of transitional horizons: those with properties of two horizons superimposed
and those with the two properties separate.
For horizons dominated by properties of one master horizon but having subordinate properties of
another, two capital letter symbols are used, such as AB, EB, BE and BC. The master horizon symbol
that is given first designates the dominant properties: an AB horizon, for example, has
characteristics of both an overlying A horizon and an underlying B horizon, but is more like the A
than like the B.
In some cases, a horizon can be designated as transitional even if one of the master horizons to
which it is apparently transitional is not present. A BE horizon may be recognized in a truncated soil
if its properties are similar to those of a BE horizon in a soil in which the overlying E horizon has not
been removed. An AB or a BA horizon may be recognized where bedrock underlies the transitional
horizon. A BC horizon may be recognized even if no underlying C horizon is present; it is
transitional to assumed parent material. A CR horizon can be used for weathered bedrock which
can be dug with a spade though roots cannot penetrate except along fracture planes.
Horizons or layers in which distinct parts have recognizable properties of two kinds of master
horizons are indicated as above, but the two capital letters are separated by a stroke (/), as E/B, B/E,
B/C or C/R. Commonly, most of the individual parts of one component are surrounded by the other
material.
2.3 Subordinate characteristics within master horizons and layers
Designations of subordinate distinctions and features within the master horizons and layers are
based on characteristics observable in the field. Lower case letters are used as suffixes to designate
specific kinds of master horizons and layers, and other features. The list of symbols and terms is
explained more in detail below:
Suffix
Description
Use for
a
Evidence of cryoturbation: Irregular or broken boundaries, sorted rock
fragments (patterned ground), or organic matter in the lower boundary
between the active layer and permafrost layer.
No restriction
b
Buried horizon: Used in mineral soils to indicate identifiable buried horizons
with characteristics that were formed before burial. Horizons may or may
not have developed in the overlying materials which may be either like, or
unlike, the assumed parent material of the buried soil. The symbol is not
used in organic soils or to separate an organic layer from a mineral layer, in
cryoturbated soils, or with C layers.
Mineral
horizon,
not cryoturbated
c
Concretions or nodules: In mineral soil it indicates a significant
accumulation of concretions or of nodules. The nature and consistence of
the nodules is specified by other suffixes and in the horizon description.
Mineral horizon
d
Dense layer: Used in mineral soils to indicate a layer of relatively unaltered,
mostly earthy material that is not cemented but that has such bulk density
Mineral horizon

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Suffix
Description
Use for
or internal organization that roots cannot enter except in cracks; the symbol
is not used in combination with the symbols m (cementation) and x
(fragipan).
f
Frozen soil: Designates a horizon or layer that contains permanent ice or is
perennially colder than 0°C. It is not used for seasonally frozen layers or for
bedrock (R). Dry frozen soil layers may be labelled (f).
Not in I and R
horizons
g
Stagnic conditions: Designates a horizon with a distinct pattern of mottling
that reflects alternating conditions of oxidation and reduction of
sesquioxides, caused by seasonal surface waterlogging. If aggregates are
present, the interiors of the aggregates show oxidising colours and the
surface parts reducing colours.
No restriction
h
Accumulation of organic matter: Designates the accumulation of organic
matter in a mineral horizon. The accumulation may occur in a surface
horizon or in subsurface horizons (through illuviation).
Mineral horizon
i
Slickensides: In mineral soils, denotes the occurrence of slickensides, i.e.
oblique shear faces caused by the shrink-swell action of clay; wedge-shaped
polished peds and seasonal surface cracks are commonly present.
No restriction
j
Jarosite: Indicates the presence of jarosite (straw-yellow) mottles, coatings
or hypodermic coatings.
No restriction
k
Accumulation of pedogenetic carbonates: Indicates an accumulation of
alkaline earth carbonates, commonly calcium carbonate.
No restriction
l
Capillary fringe mottling: Indicates mottling caused by ascending
groundwater. If aggregates are present, the interiors of the aggregates
show reducing colours and the surface parts oxidising colours.
No restriction
m
Strong cementation or induration: In mineral soils, indicates continuous or
nearly continuous cementation - used only for horizons that are more than
90 % cemented, though they may be fractured. The layer restricts rooting to
fracture planes. The single predominant or co-dominant cementing agent
may be indicated using defined letter suffixes single or in pairs. If the
horizon is cemented by carbonates km is used; by silica, qm; by iron, sm; by
gypsum, ym; by both lime and silica, kqm; by salts more soluble than
gypsum, zm.
Mineral horizons
n
Pedogenetic accumulation of exchangeable sodium.
No restriction
o
Residual accumulation of iron/aluminium oxides: Indicates residual
accumulation of sesquioxides, as opposed to the symbol s, which indicates
illuvial accumulation of oxides or organic and oxide mixture.
No restriction
p
Ploughing or other artificial disturbance: Indicates mixing of the surface
layer by ploughing or other tillage practices. A disturbed organic horizon is
designated Op or Hp. A disturbed mineral horizon, even though clearly
originally an E, B or C, is designated Ap.
No restriction; E, B
or C as Ap
q
Accumulation of pedogenetic silica: If silica cements the layer and
cementation is continuous or nearly continuous, qm is used.
No restriction
r
Strong reduction: Indicates presence of iron in reduced state. If r is used
with B, pedogenetic change in addition to reduction is implied; if no other
change has taken place, the horizon is designated Cr.
No restriction
s
Illuvial accumulation of iron/aluminium oxides: Used with B to indicate the
accumulation of illuvial, amorphous, dispersible organic matter-oxide
complexes if the value and chroma of the horizon are more than 3. The
symbol is also used in combination with h as Bhs if both the organic matter
and oxide components are significant and both value and chroma are
approximately 3 or less.
B horizon
t
Accumulation of clay: Used with B or C to indicate an accumulation of clay
that either has formed in the horizon or has been moved into it by
illuviation, or both. At least some part should show evidence of clay
accumulation in the form of coatings on ped surfaces or in pores, as
lamellae, or as bridges between mineral grains.
B and C horizon
u
Urban and other man-made materials: Used to indicate the dominant
H, O, A, E, B and C

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Suffix
Description
Use for
presence of man-made materials.
horizons
v
Plinthite: Indicates the presence of iron-rich, humus-poor material that is
firm or very firm when moist and that hardens irreversibly when exposed to
the atmosphere. When hardened, it is no longer called plinthite but a
hardpan, ironstone, a petroferric or a skeletic phase – in which case v is used
in combination with m.
No restriction
w
Development of colour or structure in B: Indicates development of colour or
structure, or both, in B horizons lacking other diagnostic characteristics. It is
not used to indicate a transitional horizon.
B horizons
x
Fragipan: Brittle consistency or high bulk density attributed to pedogenetic
processes.
No restriction
y
Pedogenetic accumulation of gypsum.
No restriction
z
Pedogenetic accumulation of salts more soluble than gypsum.
No restriction

Conventions for using letter suffixes
Many master horizons and layers that are symbolized by a single capital letter will have one or
more lowercase letter suffixes. More than three suffixes is cumbersome. The following rules apply:
•
Letter suffixes should immediately follow the capital letter;
•
A B horizon that has significant accumulation of clay and also shows evidence of development
of colour or structure, or both, is designated Bt (t has precedence over w, s and h);
•
Suffixes are listed alphabetically.
2.4 Vertical subdivisions
A horizon or layer designated by a single combination of letter symbols can be subdivided using
arabic numerals following the letters. Within a C, for example, successive layers could be C1, C2, C3,
etc.; or if the lower part is gleyed and the upper part is not, the designations could be C1-C2-Cg1-
Cg2 or C-Cg1-Cg2-R.
These conventions apply whatever the purpose of subdivision. A horizon identified by a single set
of letter symbols may be subdivided on the basis of morphology, such as structure, colour, or
texture. These subdivisions are numbered consecutively. The numbering restarts with 1 at
whatever level in the profile. Thus Bt1-Bt2-Btk1-Btk2 is used, not Bt1-Bt2-Btk3-Btk4.
The numbering of vertical subdivisions within a horizon is not interrupted at a discontinuity
(indicated by a numerical prefix) if the same letter combination is used in both materials: Bs1-Bs2-
2Bs3-2Bs4 is used, not Bs1-Bs2-2Bs1-2Bs2. A and E horizons can be subdivided similarly, for
example Ap1, A1, A2, Ap2, A3; and E1, E2, Eg1, Eg2.
2.5 Discontinuities
In mineral soils, arabic numerals are used as prefixes to indicate discontinuities. Wherever needed,
they are used preceding A, E, B, C and R. They are not used with I, although this symbol clearly
indicate a discontinuity. These prefixes are distinct from arabic numerals used as suffixes to denote
vertical subdivisions.
A discontinuity is a significant change in particle size distribution or mineralogy that indicates a
difference in the material from which the horizons formed or a significant difference in age, or both
-unless that difference in age is indicated by the suffix b. Symbols to identify discontinuities are

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used only when they will contribute substantially to the reader’s understanding of relationships
among horizons. The stratification common in soils formed in alluvium is not designated as
discontinuities - unless particle size distribution differs markedly from layer to layer - even though
genetic horizons have formed in the contrasting layers.
Where a soil has formed entirely in one kind of material, no prefix is used (the whole profile is
material 1). Similarly, the uppermost material in a profile having two or more contrasting materials
is understood to be material 1, but the number is omitted. Numbering starts with the second layer
of contrasting material, which is designated 2. Underlying contrasting layers are numbered
consecutively. Even though a layer below material 2 is similar to material 1, it is designated 3 in the
sequence. The numbers indicate a change in the material, not the type of material. Where two or
more consecutive horizons formed in one kind of material, the same prefix number applies to all of
the horizon designations in that material, e.g. Ap-E-Bt1-2Bt2-2Bt3-2BC. The number suffixes
designating subdivisions of the Bt horizon continue in consecutive order across the discontinuity.
If an R layer is below a soil that formed in residuum and the material of the R layer is judged to be
like that from which the material of the soil weathered, the arabic number prefix is not used. If the
R layer would not produce material like that in the solum, the number prefix is used, as in A-Bt-C-2R
or A-Bt-2R. If part of the solum formed in residuum, R is given the appropriate prefix: Ap-Bt1-2Bt2-
2Bt3-2C1-2C2-2R.
In organic soils, discontinuities between different kinds of layers are not identified. In most cases
the differences are shown by the letter suffix designations, if the different layers are organic, or by
the master symbol if the different layers are mineral.