Kinetics of monoammonium phosphate-induced potassium release from selected soils

Abstract

When monoammonium phosphate fertilizer is applied to soils, the phosphate concentration is very high and the pH is quite low in the immediate vicinity of the fertilizer granule. In this study, the combined effect of phosphate and proton on the alteration of K-bearing minerals was evidently the major mechanism of the NH4H2PO4-induced K release from the soils. The data indicated that the application of NH4H2PO4 fertilizer may enhance the rate of K supply in soils and lead to the conversion of some of N and P in the fertilizer to a slowly available form in soils because of the formation of a crystalline reaction product, ammonium taranakite. -Authors