Removal of Non-exchangeable Potassium through Intensive Cropping in Greenhouse Study with Alluvial Soils

Greenhouse experiments on ten soils of alluvial origin successively cropped with maize, cowpea and wheat showed that in the absence of applied potassium, its non-exchangeable form contributed to a greater extent towards total K removal by the crops as compared with K-treated soils. Coarse textured soils appeared to be exhausted at a faster rate than the finer ones. The lower dose of 40 kg K₂O/ha resulted in less uptake from fixed (non-exchangeable) form and 80 kg K₂O/ha further reduced it. At still higher level of 120 kg K₂O/ha none of the soils released any amount of fixed K for the plants. A dose of 40 to 80 kg K₂O/ha thus appeared to be justified from uptake as well as soil fertility point of view.