Chemistry of Potassium in Soils

The availability of soil potassium (K) to plants is related to the nature of soil K reserves, the chemistry of the structural configurations and surface properties of soil components involved, and the dynamics and equilibria of K in soil environments. K selectivity of soil particles is affected by mineralogical and chemical factors. The kinetics and mechanisms of K release and exchange are fundamental to understanding the chemistry of soil K. The zero-order, first-order, Elovich, and parabolic diffusion equations have been used to describe K kinetics in clays and soils. Kinetics of reactions existing between solution, exchangeable, nonexchangeable, and mineral phases of K profoundly influence K chemistry of soil. The rate and direction of these reactions determines whether applied K will be leached into lower horizons, taken by plants, converted into unavailable forms, or released into available forms.