Effect of Rock Phosphate, Single Super Phosphate and Phosphorus Solubilizing Bacteria on Phosphorus Concentration and Dry Matter Yield of Paddy

The majority of tropical and subtropical soils are acidic which are mostly deficient in phosphorus and have strong phosphorus sorption capacity. Exploring different phosphorus inputs is essential not only to increase crop production but also to improve soil phosphorus status to avoid further soil degradation. Acidic nature of the soils of these regions help to solubilize the rock phosphate and increases the amount of phosphorus that is made available to the plants. A pot experiment was conducted in Department of Soil Science and Agricultural Chemistry of College of Agriculture, Central Agricultural University, Imphal (Manipur) during kharif season of 2021 to study the effect of rock phosphate, single super phosphate and phosphorus solubilizing bacteria on phosphorus concentration and dry matter yield of paddy. To each experimental pot, recommended dose of 60 kg of N ha-1 in the form of urea and 30 kg K2O ha-1 in the form of muriate of potash were applied as basal and thoroughly mixed with the soil. Rock phosphate and single super phosphate were administered to the pots as phosphorus sources according to different sets of treatment based on the recommended amount of 40 kg P2O5 ha-1 for paddy. Seeds were treated with Bacillus megatherium. Result revealed that the changes in soil phosphorus concentration and dry matter yield of paddy were significantly affected by rock phosphate applied either singly or in combination with single super phosphate and phosphorus solubilizing bacteria. All the parameters showed different trend of changes during the whole crop growth stages till harvest. Among the treatments higher values were recorded in soil treated with T10 (50% recommended dose of P2O5 from single super phosphate + 50% recommended dose of P2O5 from rock phosphate + phosphorus solubilizing bacteria). Addition of phosphorus solubilizing bacteria enhances release of less soluble and fixed forms into easily available form as well as reduces phosphorus fixation. Efficiency of rock phosphate as phosphorus source for crop production is improved by the solubility effect of phosphorus solubilizing bacteria.