T. Pandiaraj - Department of Agronomy, University of Agriculture and Technology, GBPUAT, Pantnagar – ۲۶۳۱۴۲, India.
S. Selvaraj - Department of Agronomy, University of Agriculture and Technology, GBPUAT, Pantnagar – ۲۶۳۱۴۲, India.
N. Ramu - Department of Agronomy, University of Agriculture and Technology, GBPUAT, Pantnagar – ۲۶۳۱۴۲, India.

The objective of this study was to investigate the effects of addition of pulses in crop sequences, crop residue management, and application of fertilizer N on soil nitrogen content, soil organic carbon, nutrient uptake, and its consequences for wheat yields. The field experiments were carried out from ۲۰۰۹ to ۲۰۱۲ in the sub-humid and sub-tropical zone of northern India. The treatments were (i) crop residue retained (+Residue) or (ii) removed (-Residue), (iii) ۱۲۰ kg N ha-۱ applied to wheat, (iv) ۱۵۰ kg N ha-۱ to maize, and (v) a control with no nitrogen applied to either wheat or maize. The cropping systems consisted of a rotation of wheat and maize or wheat and green gram. Postharvest incorporation of crop residues significantly (P< ۰.۰۵) increased the wheat grain and straw yields during ۲۰۱۰-۲۰۱۱ and ۲۰۱۱-۲۰۱۲. On average, crop residues incorporation increased the wheat grain yield by a factor of ۱.۳۱ and straw yield by ۱.۳۸. The wheat crop also responded strongly to the previous legume (green gram); grain yield increased by a factor of ۱.۸۹ and straw yield by ۲.۰۵, compared to the control. Application of fertilizer N to the preceding maize crop exerted a strong carryover effect on grain (۱.۱۸) and straw yield (۱.۲۶) wheat. Application of N fertilizer to wheat increased grain and straw yields by, respectively, a factor of ۱.۶۹ and ۱.۷۹ on average. The overall conclusion is that an improved crop residue management, combined with application of fertilizer N or incorporation of legumes greatly improves the N economy of cereal cropping systems and enhances crop productivity in soils with a low N content on the short term.

Crop rotation, Legume, maize, Organic carbon