Forms of soil potassium-A review

Abstract

The knowledge about different forms and availability of potassium is must while studying the response of crops to K. Because Potassium supply to crop plants is a complex phenomenon involving relationships among various K fractions in soil. Potassium availability to plants in general is governed by different forms of K viz water soluble K, exchangeable K, fixed K and mineral K. Plants utilize not only the readily available K but also the non-exchangeable and mineral K during the crop growth. The potassium availability to plants is determined by the rate of change in the dynamic equilibrium between different forms of K in the soil which in turn is controlled by the mineral make up, rate of weathering and exchange properties of the soil.