Nitrogen Management In Clusterbean-Indian Mustard Cropping System Under Semi-Arid Northwest Indian Conditions.

Inclusion of legumes in a cropping system can reduce reliance on synthetic fertilizers and promote crop diversification. A three year field study was conducted to investigate the nitrogen requirement of Indian mustard (Brassica juncea L.) following legume grain crop of clusterbean (Cyamopsis tetragonoloba L.). After the harvest of clusterbean, four levels of N (0, 33, 66, and 100 kg N ha^-1) were applied to the subsequent crop of Indian mustard. The seed yield of Indian mustard planted after clusterbean increased significantly up to 66 kg N ha^-1, beyond which a marginal decline in seed yield occurred during all the three years of experiment. Similarly, the highest system productivity was observed at 66 kg N ha^-1. The uptake of N, P, and K in the mustard seed increased significantly up to 66 kg N ha^-1. In the straw, however, the N, P, and K uptake increased significantly up to 100 kg N ha^-1 during all the three years. Agronomic efficiency of N decreased with increased level of N. The benefit: cost ratio recorded was the highest (11.9) at 66 kg N ha^-1 and decreased with further increase in N. The results indicated that integrating clusterbean in the cropping system could save up to 33 kg N ha^-1 in raising subsequent Indian mustard crop.