Potassium Availability in Relation to Growth of Rice in Different Soils

Changes in the progressive availability of potassium in three major soil groups of Tamil Nadu under the influence of graded doses of NPK fertilizers at successive growth stages of paddy were investigated. Black soil recorded higher available potassium than red and alluvial soils. The available potassium status steadily increased with the time of submergence. This increase was attributed to the increase in the exchangeable K from non-exchangeable form during submergence. The available potassium increased with increase in fertilizer dose at tillering stage while at flowering and post-harvest stages the differences were not marked.