Kinetics of Potassium Release from Moscuvite and Phlogopite as Influenced by Organic Acids

The release rate of potassium (K) from micaceous minerals plays a significant role in supplying K to plants. The objective of this study was to determine the most appropriate kinetic equation to describe potassium release from micaceous minerals as influenced by organic acids. Muscovite and phlogopite were made to react with 0, 500, 2000 and 4000 μM solutions of oxalic, citric and malic acids for six different periods of time with the level of released K determined through a flame photometer. Pseudo second order, Elovich, power function and parabolic diffusion models were tested to describe the K release data. The rate of K release varied with the type of organic acids and also with the kind of mica. The kinetics of K release from minerals through an application of oxalic acid was best described by a parabolic diffusion model. On the other hand, Elovich and power function models could describe potassium release from phlogopite when citric and malic acid treatments applied.