ASTM D 4972 : 2019

1.1These test methods cover the measurement of the pH of soils that will pass the 2.00 mm (No. 10) sieve. Such measurements are used in the agricultural, environmental, geotechnical, 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 given in Refs (1-6)2.

1.2Two methods for measuring the pH of soils are provided. The method to be used shall be specified by the requesting authority. When no method is specified, Method A shall be used. The pH is determined in test water and a calcium chloride solution for both methods.

1.3Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4All measured and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.

1.5This 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.