Surface samples from 3 altitudes were analysed for physico-chemical parameters, K forms, mineralogy, Q/I and K release kinetic. Dominant clay minerals were illite, mixed layer, HIV. Significant correlation of clay minerals with K forms indicated their dependence on minerals. Activity ratios values were higher in low altitude than mid & high altitudes. PBCK showed wide variation. Ca2+ saturated soils and their separates were equilibrated with oxalic acid and H+-resin for NEK release. Much higher K released to H+-resin than oxalic acid. NEK release was faster initially and then gradual. NEK was maximum in clay, followed by whole soil. Sand fractions released higher quantities of K than silt, using oxalic acid but in H+-resin, silt and fine sand released almost equal K and sand released low K. kinetics of K release were evaluated using kinetic equations. Potassium releasing power of soils was assessed by successively growing mustard, maize and oat. Better correlation coefficients between...
