SEDL / STP / STP805-EB / STP33543S

A Method for Evaluating the Soil's Effective Cation Exchange Capacity and Exchangeable Base Content Using Silver-Thiourea

Hoddinott, KB
Soil scientist, U.S. Army Environmental Hygiene Agency, Aberdeen Proving Ground, MD

Pages: 16    Published: Jan 1983

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Abstract

Measurement of the soil's in situ or effective cation exchange capacity (ECEC) is of major concern to professionals dealing with land disposal of cation-containing wastes. The ECEC is a measurement of the amount of excess negative charge a unit weight of soil will display under the environmental conditions experienced in the field. The measurement is accomplished by extracting all of the cations that would be released under field conditions using an unbuffered 0.01 M silver-thiourea solution and analyzing this extract for total calcium, magnesium, hydrogen, aluminum, potassium, and sodium. The ECEC then is calculated as the sum of these six cations in units of milliequivalents per 100 g of oven-dried soil.