A diffusion interpretation of soil phosphorus desorption
1983
Sharpley, Andrew N. | AHUJA, L. R.
In earlier papers, we showed the applicability of a power-form equation to describe the kinetics of soil P desorption for several soils in laboratory batch experiments and in a rainfall-runoff processwhere Pd is the amount of P desorbed in time t at a water: soil ratio of W, with Po being the initial amount of desorbable P present in the soil, and K, α, and β constants for a given soil. In this note, we have attempted to explain the above equation in terms of diffusion-controlled desorption. The development utilized some empirical deductions from the literature. The basic desorption rate equation is formulated as a diffusion equation, with the diffusion coefficient taken as a power function of the fraction of Po yet to be desorbed. This basic formulation is tested on experimental data for different levels of Po and t, at a large value of W. The basic equation is integrated and the results are simplified to derive the equation for Pd given above.
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