Impact of Organic-Matter Application on Phosphorus-Desorption Kinetics in Two Agricultural Soils in Southeastern Iran

Phosphorus (P) desorption from soil is one process that governs P uptake by roots and its subsequent utilization in plant growth. The objective of this research was to study the kinetics of P desorption in agricultural soils of Kerman in the unamended and amended soils. For this purpose, 4% of organic manure was added to each soil. The soils were incubated for 90 days. Afterward, the desorption of P was studied by the successive extraction with 0.5 M sodium bicarbonate (NaHCO3). The results of this research indicated that the P-desorption rate was initially rapid and then became slower until equilibrium was approached. The addition of the organic matter increased P desorption in the soils studied. The kinetic data were best described by power function and simple Elovich equations. The parabolic diffusion equation was also well fitted to the time-dependent P-desorption data.