ASTM D4972-13
(Test Method)Standard Test Method for pH of Soils
Standard Test Method for pH of Soils
SIGNIFICANCE AND USE
5.1 The pH of the soil is a useful variable in determining the solubility of soil minerals and the mobility of ions in the soil and assessing the viability of the soil-plant environment.
5.2 pH measurements are made in both water and a calcium chloride solution because the calcium displaces some of the exchangeable aluminum. The low ionic strength counters the dilution effect on the exchange equilibrium by setting the salt concentration of the solution closer to that expected in the soil solution. The pH values obtained in the solution of calcium chloride are slightly lower than those measured in water due to the release of more aluminum ions which then hydrolyses. Therefore, both measurements are required to fully define the character of the soil's pH.
5.3 For the purpose of this test method the test soil must be sieved through a 2-mm (No. 10) sieve. Measurements on soils or soil fractions having particle sizes larger than 2 mm by this test method may be invalid. If soil or soil fractions with particles larger than 2 mm are used, it must be stated in the report since the results may be significantly different.
5.4 All water used for this test method must be ASTM Type III or better. Type III water is defined by Specification D1193. It is prepared by distillation, ion exchange, reverse osmosis, or a combination thereof.
SCOPE
1.1 This test method covers the measurement of the pH of soils for uses other than for corrosion testing. Such measurements are used in the agricultural, environmental, and natural resources fields. This measurement determines the degree of acidity or alkalinity in soil materials suspended in water and a 0.01 M calcium chloride solution. Measurements in both liquids are necessary to fully define the soil's pH. This variable is useful in determining the solubility of soil minerals and the mobility of ions in the soil and assessing the viability of the soil-plant environment. A more detailed discussion of the usefulness of this parameter is not warranted here; however, it can be found in many discussions of the subject. A few such discussions are given as Refs (1-6)2 at the end of the text.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 All measured and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
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Designation: D4972 − 13
Standard Test Method for
1
pH of Soils
This standard is issued under the fixed designation D4972; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* D1193 Specification for Reagent Water
D3740 Practice for Minimum Requirements for Agencies
1.1 This test method covers the measurement of the pH of
Engaged in Testing and/or Inspection of Soil and Rock as
soils for uses other than for corrosion testing. Such measure-
Used in Engineering Design and Construction
ments are used in the agricultural, environmental, and natural
D6026 Practice for Using Significant Digits in Geotechnical
resources fields. This measurement determines the degree of
Data
acidity or alkalinity in soil materials suspended in water and a
G51 Test Method for Measuring pH of Soil for Use in
0.01 M calcium chloride solution. Measurements in both
Corrosion Testing
liquids are necessary to fully define the soil’s pH.This variable
is useful in determining the solubility of soil minerals and the
3. Terminology
mobility of ions in the soil and assessing the viability of the
3.1 Definitions:
soil-plant environment. A more detailed discussion of the
3.1.1 For common definitions of terms used in this standard,
usefulness of this parameter is not warranted here; however, it
refer to Terminology D653.
can be found in many discussions of the subject. A few such
2
discussions are given as Refs (1-6) at the end of the text.
4. Summary of Test Method
1.2 The values stated in SI units are to be regarded as
4.1 Measurement of the pH of soils in both suspensions of
standard. No other units of measurement are included in this
water and a calcium chloride solution are made with either a
standard.
potentiometer using a pH sensitive electrode system (Method
1.3 All measured and calculated values shall conform to the
A), or pH sensitive paper (Method B). The potentiometer is
guidelines for significant digits and rounding established in
calibrated with buffer solutions of known pH.The pH sensitive
Practice D6026.
paper is a less accurate measurement and should only be used
1.4 This standard does not purport to address all of the
for a rough estimate of the soil pH.The electrode must be used
safety concerns, if any, associated with its use. It is the
forthismeasurementunlessthepHsensitivepaperisspecified.
responsibility of the user of this standard to establish appro-
NOTE 1—The quality of the result produced by this standard is
priate safety and health practices and determine the applica-
dependent on the competence of the personnel performing it, and the
bility of regulatory limitations prior to use.
suitability of the equipment and facilities used. Agencies that meet the
criteria of Practice D3740 are generally considered capable of competent
2. Referenced Documents
and objective testing/sampling/inspection and the like. Users of this
3
standard are cautioned that compliance with Practice D3740 does not in
2.1 ASTM Standards:
itself assure reliable results. Reliable results depend on many factors;
C670 Practice for Preparing Precision and Bias Statements
Practice D3740 provides a means of evaluating some of those factors.
for Test Methods for Construction Materials
D653 Terminology Relating to Soil, Rock, and Contained
5. Significance and Use
Fluids
5.1 The pH of the soil is a useful variable in determining the
solubility of soil minerals and the mobility of ions in the soil
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
and assessing the viability of the soil-plant environment.
Rock and is the direct responsibility of Subcommittee D18.22 on Soil as a Medium
for Plant Growth.
5.2 pH measurements are made in both water and a calcium
Current edition approved Nov. 1, 2013. Published November 2013. Originally
chloride solution because the calcium displaces some of the
approved in 1989. Last previous edition approved in 2007 as D4972 – 01 (2007).
exchangeable aluminum. The low ionic strength counters the
DOI: 10.1520/D4972-13.
2
dilution effect on the exchange equilibrium by setting the salt
The boldface numbers in parentheses refer to a list of references at the end of
this standard.
concentration of the solution closer to that expected in the soil
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
solution. The pH values obtained in the solution of calcium
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
chloride are slightly lower than those measured in water due to
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the rel
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4972 − 01 (Reapproved 2007) D4972 − 13
Standard Test Method for
1
pH of Soils
This standard is issued under the fixed designation D4972; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This test method covers the measurement of the pH of soils for uses other than for corrosion testing. Such measurements
are used in the agricultural, environmental, and natural resources fields. This measurement determines the degree of acidity or
alkalinity in soil materials suspended in water and a 0.01 M calcium chloride solution. Measurements in both liquids are necessary
to fully define the soil’s pH. This variable is useful in determining the solubility of soil minerals and the mobility of ions in the
soil and assessing the viability of the soil-plant environment. A more detailed discussion of the usefulness of this parameter is not
2
warranted here; however, it can be found in many discussions of the subject. A few such discussions are given as Refs (1-6) at
the end of the text.
1.2 The values givenstated in SI units are to be regarded as the standard. No other units of measurement are included in this
standard.
1.3 All measured and calculated values shall conform to the guidelines for significant digits and rounding established in Practice
D6026.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
3
2.1 ASTM Standards:
C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
D653 Terminology Relating to Soil, Rock, and Contained Fluids
D1193 Specification for Reagent Water
D3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in
Engineering Design and Construction
D6026 Practice for Using Significant Digits in Geotechnical Data
G51 Test Method for Measuring pH of Soil for Use in Corrosion Testing
3. Terminology
3.1 Definitions:
3.1.1 For common definitions of terms used in this standard, refer to Terminology D653.
4. Summary of Test Method
4.1 Measurement of the pH of soils in both suspensions of water and a calcium chloride solution are made with either a
potentiometer using a pH sensitive electrode system (Method A), or pH sensitive paper (Method B). The potentiometer is calibrated
with buffer solutions of known pH. The pH sensitive paper is a less accurate measurement and should only be used for a rough
estimate of the soil pH. The electrode must be used for this measurement unless the pH sensitive paper is specified.
NOTE 1—The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the
1
This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.22 on Soil as a Medium for
Plant Growth.
Current edition approved Sept. 1, 2007Nov. 1, 2013. Published October 2007November 2013. Originally approved in 1989. Last previous edition approved in 20012007
as D4972 – 01.D4972 – 01 (2007). DOI: 10.1520/D4972-01R07.10.1520/D4972-13.
2
The boldface numbers in parentheses refer to a list of references at the end of the test method.this standard.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4972 − 13
equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective
testing/sampling/inspection and the like. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results.
Reliable results depend on many factors; Practice D3740 provides a means of evaluating
...
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