KINETICS OF POTASSIUM ADSORPTION BY ALFISOLS OF GREECE

The kinetics of potassium desorption from solution to exchangeable phases was investigated on Alfisol Haploxeralf samples, which were first saturated with calcium in the form of CaCl2. Potassium adsorption was studied using 5, 25, 100, 125, 150 and 200 mugK/ml solutions and equilibrated for 10, 20, 30, 45, 60, 120, 180 and 1440 minutes. Soil pH varied between 4.0 and 9.0. Equilibrium in potassium adsorption occurred faster in lower concentrations and higher pH values. Adsorption data were plotted according to modified Freundlich, Elovich and parabolic diffusion equations. Comparisons of coefficients of determination (r2) indicated that all of the tested models successfully demonstrated potassium adsorption with the modified Freundlich equation and the Elovich equation being superior.