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 2009 to 2012 in the sub-humid and sub-tropical zone of northern India. The treatments were (i) crop residue retained (+Residue) or (ii) removed (-Residue), (iii) 120 kg N ha^-1 applied to wheat, (iv) 150 kg N ha^-1 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< 0.05) increased the wheat grain and straw yields during 2010-2011 and 2011-2012. On average, crop residues incorporation increased the wheat grain yield by a factor of 1.31 and straw yield by 1.38. The wheat crop also responded strongly to the previous legume (green gram); grain yield increased by a factor of 1.89 and straw yield by 2.05, compared to the control. Application of fertilizer N to the preceding maize crop exerted a strong carryover effect on grain (1.18) and straw yield (1.26) wheat. Application of N fertilizer to wheat increased grain and straw yields by, respectively, a factor of 1.69 and 1.79 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.

Keywords: Crop rotation, Legume, maize, Organic carbon

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