| Abstract: | Abstract Some of the common methods used for the evaluation of available phosphate in soils were studied with respect to their power of releasing phosphate present in certain phosphatic compounds and in the sorbed form. Considerable differences in the amounts extracted were observed, The anion resin extracted relatively larger quantities from Ca than from Al or Fe phosphate materials. EDTA extracted very small amounts from the Al‐phosphates in comparison with the amounts obtained from the Ca and the iron materials. Ammonium fluoride at low pH released considerable amounts of phosphate from all the phosphate materials including sorbed phosphate. The quantities of phosphate extracted by sodium bicarbonate and water were relatively low as well as those determined by isotopic exchange. |
