Critical limits of phosphorus in relation to the growth and dry matter yield of green gram (Vigna radiata L.) in acid soils of Kakching District

In a pot culture experiment, the response of Green gram plants (Vigna radiata L.) cv. DGGS-4 to phosphorus was studied on twenty acidic soils of Kakching district, Manipur. The soils were found to be acidic with a mean pH of 4.98, organic carbon content 16.76 g kg-1, EC 0.22 dSm-1, CEC 14.01 cmol (p+) kg-1, and clay content ranged from 19.79 to 83.12 per cent. Dry matter yield in the plants increased significantly with the increase of phosphatic fertilizer application. The initial P concentration in plants as well the P uptake increased significantly with increase in phosphatic fertilizers. Bray 1 (r=0.774**) and Bray 2 (r=0.741**) extracted phosphorus was found significantly correlated with Bray’s per cent yield. The critical limits of phosphorus in soils were found to be 20 kg P2O5 ha-1 for Bray 1 extracted soil phosphorus and 26 kg P2O5 ha-1 for Bray 2 extracted soil phosphorus. The critical limit of phosphorus in plant tissues were found to be 0.43 per cent.