Status and Desorption Kinetics of Potassium in Some Swell-Shrink Soils

An experiment was conducted to study the desorption characteristics of potassium in three soil series, viz. Islamnagar 3, 4 (Vertic Ustochrepts) and 5 (Udic Haplustalf) having similar exchangeable potassium levels but differing in the amount of clay. Estimates of exchangeable and reserve K were obtained on samples representing the prominent textural classes in the respective soil series. Reserve K and cumulative K desorption reflected well the changes in K status due to high intensity of cropping. Studies on K desorption were conducted using 0.01M CaCl₂ solution as an extractant over time varying from 12 h to 360 h. The first order equation was fitted to describe the K desorption in these soils. The desorption rate coefficient (kd) did not differ appreciably among samples tested possibly because of similarity in their mineralogy.