Fate of Applied Phosphorus in Some Soils of U.P.

Studies revealed that the added phosphate in soil kept infield moisture capacity for 3 days is almost completely recovered as saloid bound phosphate (NH₄Cl soluble), Al-PO₄, Fe-PO₄ and Ca-PO₄. Of the latter three forms of phosphate, Al-PO₄ was in abundance in all the soils. Recovery of added P as saloid bound P was associated with phosphate fixation capacity. Recovery in the form of reductant soluble P and occluded Fe-PO₄ was nothing. When the soil was fractionated for the above fractions after 100 days of P application, it was observed that, as the time elapsed, the saloid bound phosphate and Al-PO₄ changed gradually into iron phosphate which was the least soluble among them.