SIST EN ISO 11274:2014

SLOVENSKI STANDARD
SIST EN ISO 11274:2014
01-maj-2014
.DNRYRVWWDO'RORþHYDQMHNDUDNWHULVWLN]DGUåHYDQMDYRGH/DERUDWRULMVNHPHWRGH
,62&
Soil quality - Determination of the water-retention characteristic - Laboratory methods
(ISO 11274:1998 + C1:2009)
Bodenbeschaffenheit - Bestimmung des Wasserrückhaltevermögens - Laborverfahren
(ISO 11274:1998 + Cor. 1:2009)
Qualité du sol - Détermination de la caractéristique de la rétention en eau - Méthodes de
laboratoire (ISO 11274:1998 + C1:2009)
Ta slovenski standard je istoveten z: EN ISO 11274:2014
ICS:
13.080.40 Hidrološke lastnosti tal Hydrological properties of
soils
SIST EN ISO 11274:2014 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 11274:2014

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SIST EN ISO 11274:2014

EUROPEAN STANDARD
EN ISO 11274

NORME EUROPÉENNE

EUROPÄISCHE NORM
March 2014
ICS 13.080.40
English Version
Soil quality - Determination of the water-retention characteristic -
Laboratory methods (ISO 11274:1998 + Cor 1:2009)
Qualité du sol - Détermination de la caractéristique de la Bodenbeschaffenheit - Bestimmung des
rétention en eau - Méthodes de laboratoire (ISO Wasserrückhaltevermögens - Laborverfahren (ISO
11274:1998 + Cor 1:2009) 11274:1998 + Cor 1:2009)
This European Standard was approved by CEN on 13 March 2014.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11274:2014 E
worldwide for CEN national Members.

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SIST EN ISO 11274:2014
EN ISO 11274:2014 (E)
Contents Page
Foreword .3
2

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SIST EN ISO 11274:2014
EN ISO 11274:2014 (E)
Foreword
The text of ISO 11274:1998, including Cor 1:2009 has been prepared by Technical Committee ISO/TC 190
“Soil quality” of the International Organization for Standardization (ISO) and has been taken over as
EN ISO 11274:2014 by Technical Committee CEN/TC 345 “Characterization of soils” the secretariat of which
is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by September 2014, and conflicting national standards shall be
withdrawn at the latest by September 2014.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 11274:1998, including Cor 1:2009 has been approved by CEN as EN ISO 11274:2014 without
any modification.
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SIST EN ISO 11274:2014

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SIST EN ISO 11274:2014
INTERNATIONAL ISO
STANDARD 11274
First edition
1998-07-01
Soil quality — Determination of the water-
retention characteristic — Laboratory
methods
Qualité du sol — Détermination de la caractéristique de la rétention en
eau — Méthodes de laboratoire
A
Reference number
ISO 11274:1998(E)

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SIST EN ISO 11274:2014
ISO 11274:1998(E)
Contents Page
1 Scope . 1
2 Definitions . 1
3 Guidelines for choice of method . 2
4 Sampling . 3
Determination of the soil water characteristic using sand,
5
kaolin and ceramic suction tables . 5
6 Determination of soil water characteristic using a porous
plate and burette. 8
7 Determination of soil water characteristic by pressure
plate extractor. 11
8 Determination of soil water characteristic using pressure
membrane cells . 13
9 Precision . 15
Annexes .
A (informative)  Construction of suction tables . 16
B (informative)  Bibliography. 20
©  ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
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SIST EN ISO 11274:2014
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ISO ISO 11274:1998(E)
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.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard ISO 11274 was prepared by Technical Committee
ISO/TC 190, Soil quality, Subcommittee SC 5, Physical methods.
Annexes A and B of this International Standard are for information only.
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Introduction
Soil water content and matric pressure are related to each other and
determine the water-retention characteristics of a soil. Soil water which is in
equilibrium with free water is at zero matric pressure (or suction) and the
soil is saturated. As the soil dries, matric pressure decreases (i.e. becomes
more negative), and the largest pores empty of water. Progressive
decreases in matric pressure will continue to empty finer pores until
eventually water is held in only the finest pores. Not only is water removed
from soil pores, but the films of water held around soil particles are reduced
in thickness. Therefore a decreasing matric pressure is associated with a
decreasing soil water content [5], [6]. Laboratory or field measurements of
these two parameters can be made and the relationship plotted as a curve,
called the soil water-retention characteristic. The relationship extends from
6
saturated soil (approximately 0 kPa) to oven-dry soil (about 210 kPa).
The soil water-retention characteristic is different for each soil type. The
shape and position of the curve relative to the axes depend on soil
properties such as texture, density and hysteresis associated with the
wetting and drying history. Individual points on the water-retention
characteristic may be determined for specific purposes.
The results obtained using these methods can be used, for example:
- to provide an assessment of the equivalent pore size distribution (e.g.
identification of macro- and micropores);
- to determine indices of plant-available water in the soil and to classify
soil accordingly (e.g. for irrigation purposes);
- to determine the drainable pore space (e.g. for drainage design,
pollution risk assessments);
- to monitor changes in the structure of a soil (caused by e.g. tillage,
compaction or addition of organic matter or synthetic soil
conditioners);
- to ascertain the relationship between the negative matric pressure and
other soil physical properties (e.g. hydraulic conductivity, thermal
conductivity);
- to determine water content at specific negative matric pressures (e.g.
for microbiological degradation studies);
- to estimate other soil physical properties (e.g. hydraulic conductivity).
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SIST EN ISO 11274:2014
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INTERNATIONAL STANDARD  ISO ISO 11274:1998(E)
Soil quality — Determination of the water-retention
characteristic — Laboratory methods
1  Scope
This International Standard specifies laboratory methods for determination of the soil water-retention characteristic.
This International Standard applies only to measurements of the drying or desorption curve.
Four methods are described to cover the complete range of soil water pressures as follows:
a) method using sand, kaolin or ceramic suction tables for determination of matric pressures from 0 kPa to
- 50 kPa;
b) method using a porous plate and burette apparatus for determination of matric pressures from 0 kPa
to - 20 kPa;
c) method using a pressurized gas and a pressure plate extractor for determination of matric pressures from
- 5 kPa to - 1500 kPa;
d) method using a pressurized gas and pressure membrane cells for determination of matric pressures from
- 33 kPa to - 1500 kPa.
Guidelines are given to select the most suitable method in a particular case.
2  Definitions
For the purposes of this International Standard, the following definitions apply.
2.1
soil water-retention characteristic
relation between soil water content and soil matric head of a given soil sample
2.2
matric pressure
amount of work that must be done in order to transport, reversibly and isothermally, an infinitesimal quantity of
water, identical in composition to the soil water, from a pool at the elevation and the external gas pressure of the
point under consideration, to the soil water at the point under consideration, divided by the volume of water
transported
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2.3
water content mass ratio
w
mass of water evaporating from the soil when dried to constant mass at 105 °C, divided by the dry mass of the soil
(i.e. the ratio between the masses of water and solid particles within a soil sample)
2.4
water content volume fraction
q
volume of water evaporating from the soil when dried to constant mass at 105 °C, divided by the original bulk
volume of the soil (i.e. the ratio between the volume of liquid water within a soil sample and the total volume
including all pore space of that sample)
NOTE 1  The soil water-retention characteristic is identified in the scientific literature by various names including soil water
release curve, soil water-retention curve, pF curve and the capillary pressure-saturation curve. Use of these terms is
deprecated.
NOTE 2  The pascal is the standard unit of pressure but many other units are still in use. Table A.1 provides conversions for
most units.
NOTE 3  Sometimes suction is used instead of pressure to avoid the use of negative signs (see Introduction). However, this
term can cause confusion and is deprecated as an expression of the matric pressure.
NOTE 4  For swelling and shrinking soils, seek the advice of a specialist laboratory since interpretation of water-retention data
will be affected by these properties.
3  Guidelines for choice of method
Guidelines are given below to help select the most suitable method in a particular case.
3.1  Sand, kaolin or ceramic suction tables for determination of pressures from 0 kPa to – 50 kPa
The sand, kaolin and ceramic suction table methods are suitable for large numbers of determinations at high
pressures on cores or aggregates of different shapes and sizes. Analyses on samples of a wide range of textures
and organic matter contents can be carried out simultaneously since equilibration is determined separately for each
core. The suction table methods are suitable for a laboratory carrying out analyses on a routine basis and where
regular equipment maintenance procedures are implemented.
3.2  Porous plate and burette apparatus for determination of pressures from 0 kPa to – 20 kPa
The porous plate and burette apparatus allows analysis of only one sample at a time, and several sets of equipment
are therefore necessary to enable replication and full soil profile characterization. The method is particularly suited
to soils with weak structures and sands which are susceptible to slumping or slaking, since minimal sample
disturbance occurs. Capillary contact is not broken during the procedure and all samples, particularly soils with
higher organic matter content or sandy textures, will equilibrate more rapidly using this technique. This is a simple
technique suitable for small laboratories.
3.3  Pressure plate extractor for determination of pressures from – 5 kPa to – 1500 kPa
The pressure plate method can be used for determinations of all pressures to - 1500 kPa. However, different
specifications of pressure chambers and ceramic plates are required for the range of pressures, e.g. 0 kPa to
20 kPa, 20 kPa to 100 kPa and 100 kPa to 1500 kPa. The method is, however, best suited to pressures of - 33 kPa
or lower, since air entrapment at high negative pressures can occur. It is preferable that soils with similar water-
release properties are analysed together to ensure equilibration times are approximately the same, though in
practice it may be difficult. Sample size is usually smaller than for the previous two methods and therefore the
technique is less suitable for heterogeneous soil horizons, or for those with a strong structural composition. Analysis
of disturbed soils is traditionally carried out using this method.
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3.4  Pressure membrane cells for determination of pressures from – 33 kPa to – 1500 kPa
The pressure membrane cell should only be used for pressures below - 33 kPa. Capillary contact at higher
pressures is not satisfactory for this method. The method is appropriate for all soil types though the use of double
membranes is recommended for coarse (sandy) textured soils. Sample size can be selected (according to the size
of the pressure cell) to take into account soil structure. Different textures can be equilibrated separately using a
suite of cells linked to one pressure source.
4  Sampling
4.1  General requirements
It is essential that undisturbed soil samples are used for measurement at the high matric pressure range 0 kPa to
– 100 kPa, since soil structure has a strong influence on water-retention properties. Use either undisturbed cores or,
if appropriate, individual peds for low matric pressure methods (< - 100 kPa).
Soil cores shall be taken in a metal or plastic sleeve of a height and diameter such that they are representative of
the natural soil variability and structure. The dimensions of samples taken in the field are dependent on the texture
and structure of the soil and the test method which is to be used. Table 1 provides guidance on suitable sample
sizes for the different methods and soil structure.
Take soil cores carefully to ensure minimal compaction and disturbance to structure, either by hand pressure in
suitable material or by using a suitable soil corer. Take a minimum of three representative replicates for each freshly
exposed soil horizon or layer; more replicates are required in stoney soils. Record the sampling date, sample grid
reference, horizon and sampling depths. Dig out the sleeve carefully with a trowel, trim roughly the two faces of the
cylinder with a knife and if necessary adjust the sample within the sleeve before fitting lids to each end, and label
the top clearly with the sample grid reference, the direction of the sampling (horizontal or vertical), horizon number
and sample depth.
Wrap the samples (e.g. in plastic bags) to prevent drying. Wrap aggregates (e.g.in aluminium foil or plastic film) to
retain structure and prevent drying. Alternatively, excavate blocks measuring approximately 30 cm cube of
undisturbed soil in the field, wrap in metal foil, wax (to retain structure and prevent drying) and take to the laboratory
for subdivision. Store the samples at 1 °C to 2 °C to reduce water loss and suppress biological activity until they are
required for analyses. Treat samples having obvious macrofaunal activity with a suitable biocide, e.g. 0,05 % copper
sulfate solution.
Table 1 — Recommended sample sizes (height 3 diameter) for the different test methods
Dimensions in millimetres
Test Structure
method
Coarse Medium Fine
Suction table 50 3 100 40 3 76 24 3 50
Porous plate 50 3 76 40 3 76 20 3 36
Pressure plate 10 3 76 10 3 50
Pressure membrane 20 3 76 10 3 50
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NOTE 1 The points mentioned here are specific to water-retention analyses. Reference is made to ISO 10381-1 in which
general advice on sampling and problems encountered is given.
NOTE 2 In moist conditions, soil is easier to sample and in shrink/swell soils the bulk density under natural conditions is
lowest. It is therefore preferable to take samples in the wet season when soil matric pressures are at or near - 5 kPa. Dry
conditions should be avoided, especially for clayey soils, which are both difficult to core when dry and contract and swell with
varying water content. Samples of swelling and shrinking soils can be taken in cores only under completely saturated
conditions, i.e. under the water table and in the full capillary zone. In all other circumstances peds should be taken.
NOTE 3 Other relevant site information should be noted, e.g. soil water status, topsoil/surface conditions, etc. (see clause 5.6).
4.2  Sample preparation
To prepare samples for water-retention measurements at pressures greater than - 50 kPa (see clause 3), trim
undisturbed cores flush with the ends of the container and replace one lid with a circle of polyamide (nylon) mesh,
similar close-weave material or paper if the water-retention characteristic is known, secured with an elastic band.
The mesh will retain the soil sample in the sleeve and enable direct contact with the soil and the porous contact
medium. Avoid smearing the surface of clayey soils. Remove any small projecting stones to ensure maximum
contact and correct the soil volume if necessary. Replace the other lid to prevent drying of the sample by
evaporation. Prepare soil aggregates for high matric pressure measurements by levelling one face and wrapping
other faces in aluminium foil to minimize water loss. Disturbed soils should be packed into a sleeve with a mesh
attached. Firm the soil by tapping and gentle pressure to obtain a specified bulk density.
Weigh the prepared samples. Ensure that the samples are brought to a pressure of less than the first equilibration
point by wetting them, if necessary, by capillary rise, mesh side or levelled face down on a sheet of foam rubber
saturated with de-aerated tap water or 0,005 mol/l calcium sulfate solution. Weigh the wet sample when a thin film
of water is seen on the surface. This water content represents the total or maximum water-holding capacity and is
calculated according to clause 6.5.
Report the temperature at which the water-retention measurements are made.
NOTE 1  It may be necessary to discard samples with large projecting stones. The chemical composition of the wetting fluid
can affect the water-retention characteristic, particularly in fine-textured soils with swelling clays. Wetting with distilled or freshly
drawn tap water is not generally recommended. De-aerated 0,005 mol/l calcium sulfate solution is suggested to represent the
chemical composition of the soil solution.
NOTE 2  The time required for wetting varies with initial soil water content and texture, being a day or two for sands and two
weeks or more for clayey soils. Except for sands, wetting needs to be slow to prevent air entrapment in samples. Care should
be taken not to leave sandy soils wetting for too long because their structure may collapse. Low-density subsoil sands without
the stabilizing influence of organic matter or roots are the most susceptible. The burette method is most suitable for this type of
soil and samples can be wetted using the procedure in 6.3. Soils should, ideally, be field-moist when the wetting is
commenced; dried soils may cause differences in the water-retention characteristic due to hydrophobia or hysteresis.
General guidelines for wetting times are:
sand 1 to 5 days
loam 5 to 10 days
clay 5 to 14 days or longer
peat 5 to 20 days.
NOTE 3  Increasing temperature causes a decrease in water content at a given pressure. It is recommended that all water-
retention measurements be made at a constant temperature of (20 ± 2) °C. Where temperature control is not available, the
laboratory temperature should be monitored as the work is conducted, and reported in the test report.
NOTE 4  Very coarse pores are not water-filled when the soil sample is saturated by capillary rise.
NOTE 5  Water can be de-aerated by boiling for 5 min. It should be stored cool in a stoppered vessel.
NOTE 6  The water-retention characteristic of swelling and shrinking soils should be determined under the same load as that
occurring in the field. Otherwise the laboratory data can deviate from the water-retention characteristic of the soil under natural
field conditions.
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5  Determination of the soil water characteristic using sand, kaolin and ceramic suction
tables
5.1  Principle
A negative matric pressure is applied to coarse silt or very fine sand held in a rigid watertight non-rusting container
(a ceramic sink is particularly suitable). Soil samples placed in contact with the surface of the table lose pore water
until their matric pressure is equivalent to that of the suction table. Equilibrium status is determined by weighing
samples on a regular basis and soil water content by weighing, oven drying and reweighing. The maximum negative
pressure which can be applied before air entry occurs is related to the pore size distribution of the packed fine sand
or coarse silt which is determined by the particle size distribution, the shape of the particles and their consolidation.
5.2  Apparatus
5.2.1  Large ceramic sink or other watertight, rigid, non-rusting container with outlet in base [dimensions about
(50 · 70 · 25) cm] and with close-fitting cover.
5.2.2  Tubing and connecting pieces to construct the draining system for the suction table.
5.2.3  Sand, silt or kaolin, as packing material for the suction table.
Commercially available graded and washed industrial sands with a narrow particle size distribution are most
suitable. The particle size distributions of some suitable sand grades and the approximate suctions they can attain
are given in table 2. It is permissible to use other packing materials, such as fine glass beads or aluminium oxide
powder, if they can achieve the required air entry values.
5.2.4  Levelling bottle, stopcock and 5-litre aspirator bottle.
5.2.5  Tensiometer system (optional).
5.2.6  Drying oven, capable of maintaining a temperature of (105 – 2) °C.
5.2.7  Balance capable of weighing with an accuracy of 0,1 % of the measured value.
NOTE  Examples of a drainage system, sand and kaolin suction tables and details of their construction are described in
Annex A.
Table 2 — Examples of sands and silica flour suitable for suction tables
Type Coarse sand Medium sand Fine sand Silica flour
Use Base of suction Surface of suction Surface of suction Surface of suction
tables tables (5 kPa matric tables (11 kPa matric tables (21 kPa matric
pressure) pressure) pressure)
Typical particle size Percent content
distribution
> 600 μm 1 1 1 0
200 μm to 600 μm 61 8 1 0
100 μm to 200 μm 36 68 11 1
63 μm to 100 μm 1 20 30 9
20 μm to 63 μm 1 3 52 43
< 20 μm 0 0 5 47
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5.3  Preparation of suction tables
Prepare suction tables using packing material that can attain the required air entry values (see table 2). In Annex A
the detailed procedure for one specific type of suction table is given as an example.
5.4  Procedure
Prepare soil cores as described in 4.2. Weigh the cores and then place them on a suction table at the desired matric
pressure. Leave the cores for 7 days. The sample is then weighed, and thereafter weighed as frequently as needed
to verify that the daily change in mass of the core is less than 0,02 %. The sample is then regarded as equilibrated
and is moved to a suction table of a lower pressure or oven dried. Samples which have not attained equilibrium
should be replaced firmly onto the suction table and the table cover replaced to minimize evaporation from the table.
NOTE  The time for reaching equilibrium is proportional to the square of the height of the sample but, as a guide, cores
normally require at least 7 days to equilibrate at each potential and sometimes 20 days or more. A minimum of 7 days is
recommended so that samples establish good capillary connectivity, enabling an equilibrium status to be more rapidly attained.
5.5  Expression of results
5.5.1  Procedure for soils containing less than 20 % stones (diameter greater than 2 mm)
5.5.1.1  Calculate the water content mass ratio at a matric pressure p using the formula:
m
mp()−m
m d
wp()=
m
m
d
where
w(p ) is the water content mass ratio at a matric pressure p , in grams;
m m
m(p ) is the mass of the soil sample at a matric pressure p , in grams;
m m
m is the mass of the oven-dried soil sample, in grams.
d
5.5.1.2  Calculate the water content on volume basis at matric pressure p using the formula:
m
mp()−m
m d
q()p =
m
V× r
w
where
u(p ) is the water content volume fraction at a matric pressure p , in cubic centimetres water per cubic
m m
centimetre soil;
m(p ) is the mass, in grams of the soil sample at a matric pressure p ;
m m
m is the mass of the oven-dried soil sample, in grams;
d
V is the volume of the soil sample, in cubic centimetres;
-3
r is the density of water, in grams per cubic centimetre (= 1 g cm ).
w
NOTE 1  If a containing sleeve, mesh and elastic band are used, these should be weighed and their weights deducted from
the total weight of the soil core to give n(p ).
m
NOTE 2  The water content volume fraction is related to the water content mass ratio as follows:
b
r

m
d s
q()p =w(p) =w()p
mm m
V × r r
w w
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where
w(p ) is the water content mass ratio at a matric pressure p , in grams water per gram soil;
m m
b
r is the bulk density of the oven-dried soil, in grams per cubic centimetre.
s
5.5.2  Conversion of results to a fine earth basis
The stone content of a laboratory soil sample may not accurately represent the field situation and therefore
conversion of data to a fine earth basis may be required for comparison of results or for correction to a field-
measured stone content. If conversion of results derived from vacuum or suction methods to a fine earth basis (f) is
required for soils containing stones, the following method shall be used:
q
t
q
=
f
(1− q )
s
where:
q is the water content of the fine earth, expressed as a fraction of volume;
f
q is the volume of stones, expressed as a
...