The Use of Extractants in Studies on Trace Metals in Soils, Sewage Sludges, and Sludge-Treated Soils

Abstract

When the main problems of trace metals in the soil were deficiencies, it was usually sufficient to know how much of an essential trace metal was “available” to an extractant, usually acetic acid, ethylene diamine tetracetic acid (EDTA), diethylene triamine pentacetic acid (DTPA), etc. (e.g., Lindsay and Norvell, 1969; Viets and Lindsay, 1973; Ministry of Agriculture, Fisheries and Food, 1981). This is fortunate because the soil chemistry of trace metals is rarely simple, and it is particularly obscure at deficiency levels, when even the least unavailable trace metal ions are held on “specific sites” whose character is difficult to establish or define, rather than in identifiable salts (Lindsay, 1979).