Effect of wheat, legume and legume enriched wheat residue and nitrogen application on soil fertility under rice-wheat cropping system

Abstract

The field experiments were conducted for two crop years of 1997 – 98 and 1998 – 99 at the Indian Agricultural Research Institute, New Delhi to study the effect of wheat, legume and legume enriched wheat residue (WR) on soil fertility under the rice-wheat cropping system. A rice-wheat cropping system without incorporation of residue depleted organic C over initial level by 0.061%, kjeldahl-N by 0.012%, available P by 0.7 kg ha − 1 and available K by 36 kg ha − 1, whereas incorporation of Sesbania green manure (SGM), mungbean residue (MBR), SGM + WR and MBR + WR increased organic C over the initial level by 0.071, 0.100, 0.163 and 0.133%, respectively, kjeldahl-N by 0.001, 0.004, 0.001 and 0.005% respectively, available P by 2.7, 5.0, 8.5 and 3.2 kg ha − 1, respectively and available K by 35, 5, 92 and 12 kg ha − 1, respectively in 2 years. As compared with no residue control, incorporation of WR increased organic C by 0.036 – 0.102%, kjeldahl-N by 0.002 – 0.007% and available K by 23 – 45 kg ha−1, whereas incorporation of SGM and MBR increased organic C by 0.082 – 0.132 and 0.103 – 0.161%, respectively, kjeldahl-N by 0.009 – 0.023 and 0.005 – 0.013%, respectively and available K by 5 – 71 and 4 – 45 kg ha − 1, respectively. Incorporation of WR with SGM and MBR was more effective and increased organic C by 0.121 – 0.224 and 0.125 – 0.194%, respectively, kjeldahl-N by 0.005 – 0.029 and 0.010 – 0.021%, respectively and available K content by 23 – 128 and 11 – 116 kg ha − 1. Nitrogen application to rice also increased organic C, kjeldahl-N, available P and available K content in soil and also increased effects of crop residues. Crop residues had no significant effect on available P content in soil. Incorporation of WR with SGM and MBR with adequate fertilizer-N is, thus, recommended for building up organic C, kjeldahl-N and available K content in soil.