Effects of soil properties on the kinetics of desorption of phosphate from Alfisols by anion‐exchange resins

Abstract

AbstractPhosphorus‐desorption rates by anion‐exchange resins were best described by three empirical kinetic models: Elovich equation, the parabolic diffusion equation, and the fractional power equation in that order. The objective of this study was to determine the relationship between kinetic rate constants from Elovich, fractional power, and parabolic rate equations and soil physical and chemical properties from soils of different lithogenic origins from the Nigerian savanna. Phosphorus‐desorption patterns included an initial fast reaction, followed by a slow release that continued up to 20 h. Particle diffusion was observed to be the rate‐limiting step in the kinetic desorption of native P in the soils studied as opposed to ligand exchange or surface reaction. The influence of parent material is not prominent due to long history of pedogenesis over the soils. The rate coefficients from the Elovich equation, parabolic diffusion equation, and the fractional power model were best predicted from clay, pH, and extractable Al and Fe oxides and therefore exert a profound influence on the rate of P release from the soils. These soil properties together explained between 93% and 99% of the variance in the rate coefficients of P desorption from the soils.