Kinetics of Potassium Desorption from Inceptisols and Entisols

The kinetics of K desorption from eleven alluvial soils of Bihar was investigated at temperatures 10, 20 and 42°C. The first order rate equation described K desorption from Inceptisols and Entisols. Approximately 85 to 98 per cent adsorbed K was subsequently desorbed from the soils. The rate coefficient of K desorption showed positive and significant correlation with clay and CEC. There was some deviation in diffusion plots during the initial period of K desorption in some soils. It indicated that diffusion-controlled exchange may not be strictly obeyed during the initial period of K desorption due to mass action exchange at sites on external surfaces. Potassium desorption as plotted by the Elovich equation in ea-saturated soils was rapid at first and leveled off with the time indicating more difficult desorption reaction. A curvilinear response of equation was observed. The non-linear Elovich plot may support the hypothesis of multireactive nature of soils.