Different Fonns of Soil K as Influenced by K Application in Normal and K Exhausted Soils

The transformation of fertilizer K in soil and its effect on the displacetment of Ca and Mg from the exchange complex was studied in a laboratory experiment. The results indicated that the Inceptisol and Vertisol had higher concentration of K, Ca and Mg than other soils and these were comparatively low in the Ultisol. Increasing K addition increased the retained Kill all the soils. Potassium retentive power did not change much in most of the cases due to exhautive cropping. In general, the extent of displacement of Ca+ Mg was about 35 to 50 per cent of K which entered into the exchange complex. The distribution of K was more in loosely bound fraction after short term anaerobic contact, both for the uncropped and exhausted soils. Part of the applied K was converted to non-exchangeable form.