Abstract
This study was undertaken to assess the effect of 6 green manure legumes viz., mungbean (Vigna radiata), cowpea (Vigna unguiculata), soybean (Glycine max), sesbania (Sesbania rostrata), pigeonpea (Cajanus cajan) and guar (Cyamopsis tetragonoloba) and N fertilizer on wheat yield in rice-wheat system for three years (2001/02-2003/04) at Agriculture Research Institute, Tarnab, Peshawar, Pakistan. The grain, straw and N yields of wheat were significantly greater in the green manure legumes than in the fallow-based rice-wheat rotation during all the three years. The average improvement gained from the green manure legumes relative to fallow-based cropping, was 18.1% for grain yield, 18.4% for straw yield and 59.7% for total N uptake in grain and straw of wheat crop. The greatest gain of 27.5% in grain yield, 24.5% in straw yield and 82.8% in N uptake of wheat occurred due to green manuring of sesbania. The effects of N fertilizer on grain, straw and N yields of wheat were also significant during all the three years. The average increase by N fertilizer was 18.2% in grain, 19.2% in straw and 46.8% in N yields of wheat crop compared with no N fertilizer treatment. Our results thus suggest that involvement of green manure legumes in rice-wheat system is highly beneficial for sustainable crop production and must be made an integral part of the cropping system.