Long-term effect of integrated nutrient management on yield sustainability and soil fertility of rice (Oryza sativa)-wheat (Triticum aestivum) cropping system

A long-term experiment was conducted on integrated nutrient management in rice (Oryza sativa)-wheat (Triti- cum aestivum L. emend. Fiori & Paol.) system at Jabalpur (Madhya Pradesh) since rainy (kharif) season 1987-88 to maintain the sustainable and high grain yields of this system without degradation of soil health under irrigated production system. The present paper deals with the studies conducted during the 2002-03 and 2003-04. Substituion of 50% N by green leaf manuring with sunnhemp (Crotalaria juncea L.) attained highest system pro- ductivity (33.12 kg grainlhdday). While determining the sustainability yield index (SYI), the value was also maxi- mum with 50% NPK + 50% N through green manuring with sunnhemp to rice, followed by 100% NPK to wheat. Maximum soil available nitrogen, phosphorus, potassium, sulphur and zinc, and minimum bulk density were no- ticed with substitution of 50% N by green manure. However, the pH value and EC were almost constant in all the treatments. lntegrated use of 50% NPK and 50% N through green manuring of sunnhemp to rice followed by 100% NPK to wheat also fetched the maximum net monetary returns (Rs 34,403lhdyear) with the benefit: cost ratio 2.40.