prEN ISO 25177

SLOVENSKI STANDARD
01-september-2026
Kakovost tal - Terenski opis tal
Soil quality - Field soil description
Bodenbeschaffenheit - Bodenbeschreibung im Felde
Qualité du sol - Description du sol sur le terrain
Ta slovenski standard je istoveten z: prEN ISO 25177
ICS:
13.080.01 Kakovost tal in pedologija na Soil quality and pedology in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 25177
ISO/TC 190
Soil quality — Field soil description
Secretariat: DIN
Qualité du sol — Description du sol sur le terrain
Voting begins on:
2026-06-30
ICS: 13.080.01
Voting terminates on:
2026-09-22
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Reference number
ISO/DIS 25177:2026(en)
DRAFT
ISO/DIS 25177:2026(en)
International
Standard
ISO/DIS 25177
ISO/TC 190
Soil quality — Field soil description
Secretariat: DIN
Qualité du sol — Description du sol sur le terrain
Voting begins on:
ICS: 13.080.01
Voting terminates on:
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 25177:2026(en)
ii
ISO/DIS 25177:2026(en)
Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 How to use this document . 2
4.1 General .2
4.2 Combined use with other description standards .3
4.3 Mandatory or optional observations .3
4.4 Accuracy and units .4
4.5 Encoding .4
5 Description objectives and methods . 4
5.1 General .4
5.2 Investigation objectives .4
5.3 Quality assurance and quality control .5
5.4 Description structure .5
6 Description of general references and general information . 5
6.1 General .5
6.2 Site/profile numbers .6
6.3 Location .6
6.4 Geographical coordinates .6
6.5 Date and time of observations .6
6.6 Author and organization .6
7 Profile environment . 7
7.1 General .7
7.2 Previous precipitation .7
7.3 Land use at plot level (checked by detailed field survey) .7
7.4 Type of cultivation or vegetation or human utilization (at the plot level) .8
7.5 Landform of the site . .8
7.6 Slope length .8
7.7 Slope value (gradient) .8
7.8 Slope orientation (aspect) .8
7.9 Nature of natural and anthropogenic soils and materials .9
7.9.1 Natural material .9
7.9.2 Anthropogenic material .9
7.10 Presence and depth to water table .10
7.10.1 General .10
7.10.2 Present depth to water table .10
7.10.3 Minimum depth to water table .10
7.10.4 Maximum depth to water table .11
7.10.5 Nature of the water .11
8 Surface appearance .11
8.1 General .11
8.2 Description of the surface material .11
8.3 Percentage of land surface occupied by rock outcrops or surface exposures of “non-
natural” material .11
8.4 Evidence of erosion . 12
9 Soil profile description . .12
9.1 General . 12
9.2 Soil descriptions made or changed after the fieldwork . 13
9.3 Soil layer or horizon description method . 13

iii
ISO/DIS 25177:2026(en)
9.4 Horizon or layer number . 13
9.5 Horizon or layer depth .14
9.6 Nature of lower horizon boundary .14
9.7 Estimation of moisture status .14
9.8 Colour of the horizon or layer matrix . 15
9.8.1 Colour description method . 15
9.8.2 Colour description . .16
9.9 Mottles .17
9.9.1 General .17
9.9.2 Mottle abundance .17
9.9.3 Mottle colour .17
9.10 Estimated organic matter content .17
9.11 Texture.18
9.11.1 Classification system used .18
9.11.2 Field determination/ estimation of particle sizes .18
9.11.3 Field determination/estimation of the coarseness of a sandy soil .18
9.11.4 Sampling for texture analyses.21
9.11.5 Description of texture diagram .21
9.12 Coarse elements.21
9.12.1 General .21
9.12.2 Coarse element abundance (in % volume fraction) .21
9.12.3 Maximum size of the most frequently observed coarse elements . 22
9.12.4 Nature of the coarse element(s) . 22
9.12.5 Non-natural or unknown coarse elements . 22
9.13 Carbonates and effervescence . 22
9.13.1 Intensity of effervescence . 22
9.13.2 Location of effervescence . 23
9.14 Main categories of soil structure . 23
9.15 Compactness .24
9.16 Total estimated porosity .24
9.17 Roots .24
9.17.1 Root abundance .24
9.17.2 Size (diameter) of most frequently observed roots . . 25
9.18 Density of worm channels . 25
9.19 Odour . . . . 25
9.20 Field detection of mineral oil in soil samples (oil-water reaction pan) . 26
9.20.1 General . 26
9.20.2 Oil floating on water . 26
9.20.3 Other oil observations . 26
10 General designation .27
10.1 General .27
10.2 Type of soil profile classification used .27
10.3 Soil type with reference to the soil classification system used .27
10.4 Type of horizon designation used . .27
10.5 Sequence of horizons .27
11 Reporting .28
11.1 General . 28
11.2 Presentation of field soil descriptions . 28
11.3 Profile diagram . 28
11.4 Documented information . 28
Annex A (informative) Landform .29
Annex B (informative) Charts for estimating proportions of mottles, coarse elements, etc. .30
[1]
Annex C (informative) Soil horizon designation — Example of the WRB .31
Annex D (informative) Examples of texture diagrams .35
Annex E (informative) Determination of soil texture in the field .37

iv
ISO/DIS 25177:2026(en)
Annex F (informative) Some types of soil structure .40
Annex G (informative) List of common materials found in soil and on the soil surface .42
Annex H (informative) Soil description observations to record for specific types of soil
investigations .44
Annex I (informative) Example field layer description method .48
Bibliography .50

v
ISO/DIS 25177:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the World
Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL:
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 190, Soil quality.
This second edition cancels and replaces the first edition (ISO 25177:2019), which has been technically
revised.
The main changes compared to the previous edition is as follows.
[1]
— The fourth edition of the World Reference Base for soil resources (2022) has been adapted.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

vi
ISO/DIS 25177:2026(en)
Introduction
Traditionally, description of soils and their environment was carried out as parts of soil surveys and soil
inventories, the purpose being to describe the pedogenic context of the soil and assess applied aspects,
principally agronomic potentials.
Today, many soil observations are made as part of either much broader, or alternatively more focused,
environmental studies, and might include analysis for objectives such as:
— identifying human influences on soils, with, particular attention being paid to the negative effects of
these influences (for example contamination with possible hazardous substances, or deterioration of
physical soil properties);
— land protection within the context of sustainable agriculture and forestry;
— assessing the fate of contaminants introduced to the soil;
— assessing the consequences arising from changes in the use of the soil;
— setting up monitoring programs for specific purposes (such as observation of changes of soil properties
over time);
— developing spatial databases (used in the context of GIS) aimed at facilitating the geographical
representation of soils;
— and for many other purposes.
While the general framework of this document has stayed the same in this updated version, additions include
references to the ISO 18400 series (see Figure 1), observations for soil contamination, and description of
artificial material and soil layers.
The description of soils and sites is often accompanied by field and laboratory measurements, and therefore
field measurement observations are included in this document.
The original text was based on aspects of the traditional approach to soil description, for example the
“Guidelines for soil description” from the FAO (Rome 2006) and the soil type classification from the World
Reference Base for soil resources (2006). The "Guidelines for soil description" is nowadays part of WRB
and the WRB is managed by a special Working Group of the International Union of Soil Sciences (IUSS). In
[1]
thisdocument, the 2022 version of WRB is used as a reference.
Soil descriptions and associated soil data are used and re-used for a variety of purposes. For wider utilization
of data from soil descriptions, this document can be used in conjunction with other (commonly and publicly
available) standards. Some types of soil information, specifically soil contamination data and data on
anthropogenic and exogenous material, were not available in earlier versions and have been included here.
Depending on the objective/s of an investigation, specific observations of interest are made and recorded.
Even within a particular field of interest, the degree of detail in the soil description in the field varies,
depending on the scope of the project.
The quality of field soil descriptions is strongly dependent on the knowledge and especially the experience
of the person making and/or recording the observations in the field, since most field observations are
estimations (sometimes with the help of reference materials and devices like colour-charts, magnifiers,
sieves, or scatter diagrams).
vii
DRAFT International Standard ISO/DIS 25177:2026(en)
Soil quality — Field soil description
1 Scope
This document provides guidance on the description of soil in the field and its environmental context. It is
applicable to natural, near-natural, urban and industrial sites. The soil observations and measurements can
be made on a project site level, on a plot level, on layer or horizon level and on specific soil constituents.
It also provides guidance on how to describe layers of anthropogenic (artificial) material or layers that were
not modified by pedogenic processes in the strict sense and how to describe coarse material of natural or
artificial origin.
This document can be used in combination with other publications that provide guidance or requirements
regarding specific aspects of soil observations and measurements.
NOTE 1 It might not be possible or necessary to record data under all the headings listed in Clause 4 to Clause 11.
[2]
NOTE 2 Overall guidance for presentation of information from soil surveys is given in ISO 15903 .
NOTE 3 The guidance provided assumes that sampling is done in accordance with ISO 18400.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 3166-1, Codes for the representation of names of countries and their subdivisions — Part 1: Country code
ISO 3166-2, Codes for the representation of names of countries and their subdivisions — Part 2: Country
subdivision code
ISO 11074, Soil quality — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11074 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at: http:// www .electropedia .org
3.1
observation
act of observing a property, with the goal of producing an estimate of the value of the property
[3]
Note 1 to entry: Adapted from ISO 19156 .

ISO/DIS 25177:2026(en)
3.2
litter layer
loose layer that contains > 90% (by volume, related to the fine earth plus all dead plant residues) recognizable
dead plant tissues (e.g. undecomposed leaves) but excluding dead plant material still connected to living
plants (e.g. Sphagnum mosses)
Note 1 to entry: Soil quality investigations generally describe the full subsurface, with the surface as depth 0 (zero).
[1]
WRB) defines the top of the mineral soil surface as depth zero and a litter layer should be noted as greater than
zero. See also 9.5.
[1]
[SOURCE: Adapted from WRB 2022 .]
4 How to use this document
4.1 General
This document describes the most commonly used field observations in soil quality investigations. The
observations are recorded at different levels:
— general/site (see Clause 6);
— profile/surface point (see Clause 7 and Clause 8);
— horizon/layer (see Clause 9 and Clause 10).
Pre-defined observations (selection list or picklists) are tabulated with their corresponding codes. Where
relevant, explanatory text is given before or after the observation to be recorded [e.g. in this subclause (4.1)].
Some observations to be recorded are so commonly understood that they are simply listed, for example in
6.5.
Where possible values associated with observations are pre-defined (picklists) and these values are defined
with percentages (%), it is also permissible to record estimated specific percentage values.
EXAMPLE Recording of a mottle abundance value of 10 % is allowed (see 9.9.2). This can also be recorded as code
“3” or as “common”.
This means that a more precise estimate can be recorded (e.g. rather than a range), however it does not
mean that the estimates are in fact more accurate, since accuracy may depend on both the requirements of
the project and skill of the observer.
For soil descriptions in the field and for digital data exchange, only the codes and values can be recorded. In
the full field report, the text of the description can also be provided. The full text descriptions belonging to
codes shall be available.
NOTE In the digital exchange of data, this might be in the form of a hint or link to the table.
The context of the information is important for the application of the results. In Figure 1, the process for soil
description is provided.
ISO/DIS 25177:2026(en)
Key
optional routes (specific part of) soil descriptions
possible purposes soil investigations (can be combined)
soil investigation primary process route
Figure 1 — Soil description process
4.2 Combined use with other description standards
This document can be used separately or in combination with standards that provide further guidance or
requirements for specific aspects of soil observations and measurements.
Where relevant, this document can be applied with the following references:
[1]
— World Reference Base for soil resources (WRB) , for example when determining soil types;
[4] [5]
— ISO 14688-1 and ISO 14688-2 .
If additional codes, descriptions or requirements from these or other complementary references is used,
these shall be recorded (see 6.1).
EXAMPLE
[1]
— ISO 25177:2027 WRB 2022
[6]
— ISO 25177:2027, ISO 18400-203:2018
4.3 Mandatory or optional observations
Where observations are mandatory, it is explicitly indicated by underlined text in this document. If not
mandatory the observations to record are optional.

ISO/DIS 25177:2026(en)
For a number of common soil investigation types, the mandatory observations are listed in Annex H. If
optional observations are described, they shall be recorded according to this document.
NOTE National legislation or project rules can demand that optional observations can be mandatory in some
contexts.
4.4 Accuracy and units
Because of the very different objectives for most field observations, no minimum accuracy is stipulated. For
some observations, the unit to be used is mandatory. The unit specified is generally the most commonly
used one and fit for the purpose for most soil descriptions.
EXAMPLE x- and y- coordinate in metres.
Depending on the accuracy required for an investigation, recording the coordinates in whole metres may
be sufficient, however, more accuracy is needed at times (for example, plus or minus 0,01 metres). The unit
used in the second case is still metres, although the accuracy may be significantly better than a whole metre.
NOTE The units and number of digits output from a given device do not automatically reflect its accuracy. For
example, a GPS measurement with 3 digits after comma or point (depending on the convention used) does not mean
that the value is accurate to 1 mm.
4.5 Encoding
Field observations can comprise different types of results. For some observations, the result should be one
of the results given in the pre-defined in picklists. For other observations, results should be recorded as
estimated or measured values. At least at all main levels (site-, profile-, layer/horizon-) there should be
capacity for free text for observations that do not match those in the pre-defined picklists.
Numeric codes in this document are defined with the same number of digits. If there are more than 9 and
less than 99, a zero is added to the codes 1 until 9 (i.e. 01, 02, 03, etc.). Numeric codes start in principle with
1, unless the first value class is zero or near-zero. In that case, the numeric codes start with zero (0).
EXAMPLE In 8.4, Code 0 = no visible erosion.
If not observed, but a code is needed for an observation, an “X” can be used.
NOTE X does not mean observed with result 0 (zero).
[1] [4]
In this document, some descriptions and associated codes are derived from WRB and/or ISO 14688-1 .
In addition, new observation results have been added, codes from the earlier version of this document might
have been changed, and new codes might have been added.
5 Description objectives and methods
5.1 General
If another reference is used in addition, this shall be clearly stated in the text of the written report or in the
meta-data of the digital data that is reported.
5.2 Investigation objectives
Soil investigations usually have specific objectives. Other standards adapted to various scopes can be
combined with this document.
Main investigation types based on project objectives or approaches include:
[7]
— investigation for contamination (e.g. according to ISO 18400-203 );
[8]
— investigation for nature or near-nature management (e.g. according to ISO 18400-205 );

ISO/DIS 25177:2026(en)
[8]
— investigation for cultivation management (e.g. according to ISO 18400-205 );
[8]
— investigation for agricultural management (e.g. according to ISO 18400-205 );
[8]
— investigation for forestry (e.g. according to ISO 18400-205 );
— investigation for archaeology;
[9]
— investigation of soil gas (e.g. according to ISO 18400-204 );
[10]
— biological investigation (e.g. according to ISO 18400-206 ).
NOTE 1 See Figure 1 for a schema of how this document can be used in combination with other standards.
NOTE 2 Annex H provides a list of the most commonly used observations of soil that can be recorded and the
importance of separate types of soil investigations.
5.3 Quality assurance and quality control
The desired accuracy and level of detail is dependent on the project scope and project objectives.
[11]
Where aspects of soil description are mentioned or given, ISO 18400-106 can be applied.
Alternatively, or in addition, other guidance on QA/QC can be applicable.
[12]
For digital exchange of soil related data ISO 28258 can be applied.
Field estimations depend on the knowledge and experience of the observer. To ensure consistent soil
observations, it is recommended to regularly undertake field soil descriptions with experienced personnel.
NOTE 1 Education and training of staff is important. Projects can benefit with staff that has experience with similar
soil sites, soil layers and scopes.
NOTE 2 Assessing inexperienced personnel’s estimates of texture for example can be done by comparing their
results with reference analysis and reference samples, and/or having them working with personnel experienced in
field soil description.
NOTE 3 A check for logical and internal consistency of field data can give a first impression of data quality.
5.4 Description structure
Soil is described at different levels.
— General level: references of a soil description, e.g. profile numbers, geographical coordinates. See Clause 5.
— Site level: observations of the location or site. The scale of the location or site is determined in the project.
A project can have different sites or locations. A site or location usually has more than one plots. See
Clause 6.
— Plot level: observations that can be made on profile level: from the borehole or in a trial pit or trench. See
Clause 7 and Clause 8.
— Layer/horizon level: observations that can be made on one spot from the surface down to the parent
material. See Clause 9.
[12]
NOTE The difference between plot and site (location) is explained in ISO 28258 .
6 Description of general references and general information
6.1 General
Record the general reference, using the following codes or descriptions:

ISO/DIS 25177:2026(en)
Table 1
Code Description
1 ISO 25177
[1]
2 ISO 25177 and WRB
[4]
3 ISO 25177 and ISO 14688-1
[1] [4]
4 ISO 25177 and WRB and ISO 14688-1
5 ISO 25177 and other standard(s) – see 4.2
Record, if relevant, (other) reference standard(s) and general information.
6.2 Site/profile numbers
Record the profile number(s) or code(s).
Record the survey number or code.
6.3 Location
Record the country.
— Codes according to ISO 3166-1 and ISO 3166-2 shall be used. For historical research, designations
[13]
according to ISO 3166-3 should be considered, when necessary.
Record the administrative division.
— To be adapted according to the country, provinces, states, regions, departments, towns. This can be
recorded uncoded and coded. If coded, the definition shall be available, for example, in code lists.
Record the toponym and address of the location.
— Place name, street and street number, postal code, local/extra place name.
6.4 Geographical coordinates
Latitude and longitude of the site should be given as accurately as possible in decimal degrees (WGS84).
Other reference systems may be used if specified.
Record the type of geographical reference system (degrees, lambert, national re
...