Contribution of Potassium from Non-exchangeable Sources in Soil to Crops

Changes in soil potassium supply and contribution of K to crops from the non exchangeable source were investigated in two soils (Typic Ustochrepts) subjected to continuous cropping and fertilizer use. While exchangeable K content of both the soils did not change appreciably even after a long period, there were pronounced changes in the non-exchangeable form. Contribution of non-exchangeable K to crops was more in untreated plots than in those receiving fertilizer K. There was significant correlation between K removal in crops and non-exchangeable K released from the soil. The non-exchangeable K contribution to crops estimated by chemical extraction method were also significantly correlated.