Potassium mineralogy, dynamics and availability in Orissa Soils

Potassium is an essential nutrient element for all living organisms including plant and animals. It is the univalent “Master Cation ” found in largest concentration (100 – 200 m M-K) in the plant cell sap. Potassium is ionic, free (not bound to any constituent) and mobile in the plants. It is nomadic in nature (can move into and out of the plants). It plays vital roles in translocation of assimilates, photosynthesis, enzyme activation (more than sixty), osmotic regulation, hence in water relations, resistance to pests and diseases and tolerance to cold, frost and crop quality. Most of the K in soil is held in the primary minerals like micas and potassic feldspars (microcline) and secondary minerals. As primary minerals weather, their rigid lattice structure becomes unstable increasingly. With passage of time, the K+ held in the interlayer spaces of 2:1 type minerals (micas) becomes more mobile, fastly through non-exchangeable but slowly available (held in between the 2:1 type crystal layers) form and finally through the readily exchangeable (held on surface of soil colloids) and the soil solution forms from which K is absorbed by plant roots. The K+ ion absorbed by plants from the soil solution is cycled through plants, human being