Central Rice Research Institute, Cuttack, Orissa, 753006.
Release of P from phosphate rocks in association with various dilute acetic acid solutions was investigated in the laboratory. A part or all of dilute acetic acid of 10−3 and 10−4 M concentration was consumed at the beginning by the accessory minerals present in the phosphate rocks leaving very little acetate ion towards release of P from apatite. Significant portion of 10−1 M acetic acid could be available for dissolution of reactive P from phosphate rocks which was related to the chemical nature of apatite present in them. There was a significantly high positive correlation between dilute acetic acid soluble P (10−1 M) and agronomic effectiveness of different phosphate rocks. Dilute (10−1 M) acetic acid could also be considered as a suitable extractant to predict the agronomic potential of phosphate rocks.
P supplying power, relative agronomic efficiency, phosphate rocks, laboratory extractant, reactive P
