The kinetics of sulphate adsorption was studied with six Calciorthents using K235SO4 at periods ranging from 3–60 minutes. Of the six kinetic equations (first order, second order, parabolic diffusion, two constant rate, Elovich and radial diffusion) tested, radial diffusion emerged as best model followed by two constant rate and Elovich equations to describe sulphate adsorption kinetics for these soils. The amount of sulphate adsorbed varied from one soil to another, and 56 to 75 per cent of applied sulphate was adsorbed at the initial stage and thereafter the rate became slower.
Kinetic models, sulphate adsorption, radial diffusion, calcareous soil
