A simple and precise colorimetric method of determining phosphate in ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid (NTA) extracts of soils is described. It involved extraction of the phosphate in soil with EDTA or NTA solution, titration of the extract with dilute hydrochloric acid to pH 1.5, filtration (to remove the slightly soluble, H-EDTA or H-NTA and mimic acid precipitates formed), and colorimetric determination of the phosphate in the filtrate by an ascorbic acid method. The method is sensitive and accurate', and it permits determination of phosphate extracted from soils by using up to 300 mM EDTA and NTA solutions.Studies of the factors affecting the release of phosphate from soils by EDTA or NTA solution showed that the release of phosphate from soils is affected by the pH, time of extraction, soil: solution ratio, and concentration of the chelating solution used, and that the organic phosphate extracted from soils by these reagents is stable at room temperature for several days.