DIRECT AND RESIDUAL EFFECTS OF BIOORGANIC AND INORGANIC FERTILIZERS IN RICE (ORYZA-SATIVA) WHEAT (TRITICUM-AESTIVUM) CROPPING SYSTEM

A field experiment was carried out for 2 years to find out the optimum combination of chemical fertilizers with blue-green algae and farmyar d manure in rice (Oryza sativa L.)-wheat (Triticum aestivum L. emend. Fiori and Paol.) cropping system. Rice-grain yield was statistically s imilar under treatments of blue green algae @ 10 kg culture/ha and far myard manure @ 5 tonnes/ha, but was significantly higher (16-17%) than the unfertilized control. Organic manure and blue green algae combine d with 60 kg N + 37.5 kg P2O5 + 22.5 kg K2O/ha as inorganic fertilizer s proved superior to other treatments and showed significantly higher yield and crop nutrient uptake than other treatments. The residual eff ect of blue green algae and organic manure with inorganic fertilizer w as significant on grain yield of wheat and on N, P and K uptake by the crop. Residual fertility in terms of organic carbon and available P i ncreased under blue green algae and farmyard manure with and without i norganic fertilizers, whereas these sources had no impact on build-up of N and K in the soil.