An overview of the adsorption, desorption and release kinetics of phosphorus in soils

Phosphorus (P) fertilizers are added to agricultural soils to improve the soil P fertility, but the release rate of P can greatly influence on P fertility of soils. In high weathered soils there are more difficulties for management of phosphorus (P) fertilization due to their high adsorption rates. The P release kinetics process in highly weathered soils mainly governed by the rapid sites on adsorption and slow sites on desorption, resulting in high levels of hysteresis. Organic acids are most effective in the release of inorganic P (Pi). P release was found higher in sandy loam texture as compared to loam texture soils due to low positive charge points and adsorption capacity. Other soil properties such as organic matter (OM) contents and cation exchange capacity (CEC) also found highly correlated in respect to P release. The main objectives of this study to understand the effects of kind of soils and land-use type on the release kinetics of P under different management practices as well as to investigate the relationship between physical and chemical properties of soils and kinetics parameters from soils. Observed that release kinetics were rapid initially later on it slower rate. To explain this kinetics of P release used different models i.e. parabolic diffusion and power equation model were found to be satisfactory for P release.