Integrated nutrient management in rice-wheat cropping system for sustainable productivity

Integrated nutrient management module for rice-wheat cropping system on an InCeptISOl was developed through field experimentation for eight consecutive crop seasons (1999-2003). The treatments consisted of FYM, vermicompost, green manure, Azotobacter, phosphate solubilizing bacteria (PSB), blue, green algae (BGA), rice residue incorporation and NPK fertilizers. Significantly higher yields to the tune of 4.3 t ha-I for rice and 4.0 t ha-I for wheat were recorded when rice-wheat were grown after green manuring of dhaincha in-situ or application of FYM (10 t ha-I yearl) or vermicompost (5 t ha-I yearl) in kharif season along with reduced quantity of fertilizers per hectare per crop (30-90 kg N, 13-20 kg P and 37 kg K) accompanied by microbial cultures (Azotobacter, BGA and PSB) as compared to the yield (4.0 - 4.1 t ha-I) with recommended dose of NPK (120-26-50) per hectare per crop. Reduction to the tune of 25 in recommended dose ofN, P and K fertilizers (30 kg N, 6.5 kg P and 13 kg K ha-I crop-I) could be made with the application of FYM or vermicompost or green manuring alone without decrease in yield of rice and wheat. Quantity ofN and P fertilizers could be further reduced to half of the recommended dose (i.e. 60 kg Nand 13 kg P ha-I crop-I) with the applicatio~f Azotobacter and PSB along with FYM or vermicompost or green manuring. Application of BGA in paddy and incorporation of rice residue before sowing of wheat further reduced the recommended dose of N fertilizer by 30 kg ha-I for both rice and wheat. Cultivation of rice and wheat on the recommended dose of NPK fertilizers alone decreased the organic carbon, available P and K content of the soil. Application of FYM, vermicompost, green manuring, and rice residue incorporation alone or in combination with biofertilizers supplemented by NPK fertilizers improved the soil fertility besides maintaining higher sustainable productivity.