Changes in productivity and soil fertility under rice (Oryza sativa)-wheat (Triticum aestivum) system as influenced by long-term integrated nutrient supply

An experiment carried out for last 11–13 consecutive years at 3 locations, viz. Ludhiana, Jabalpur and Kalyani, of AICRP on Cropping Systems in rice (Oryza sativa L.)-wheat (Triticum aestivum L. emend. Fiori & Paol.) crop sequence revealed that at Ludhiana, application of 50% recommended NPK + 50% N through FYM increased rice yield over years, while wheat yield increased linearly with farmer's practice. At Jabalpur, rice yield showed an increasing trend after 3 years of experimentation in integrated nutrient supply, whereas wheat yield registered upward trend after 5 years with chemical fertilizers and also with integrated nutrient supply. At Kalyani, static trend in rice yield was noticed in chemical fertilizers and some integrated nutrient supply treatments, while linear increase in wheat yield was observed with farmer's practice. Integrated nutrient supply had favourable effect on available NPK at all the locations except N and P at Jabalpur under, continuous rice-wheat sytsem. Economic analysis indicated that the maximum net returns of Rs 38,388 could be realized at Ludhiana when 75% recommended NPK + 25% N through green-manuring was applied to rice followed by 75% nitrogen to wheat, whereas the maximum net returns of Rs 27,061/ha/year at Jabalpur and of Rs 22,658/ha/year at Kalyani could be recorded with the use of 50% recommended NPK+ 50% N through green-manuring to rice and 100% NPK to wheat.