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A field study was carried out at the Indian Agricultural Research Institute, New Delhi, India, for three crop years (2000-2001 to 2003-2004) to find out the effect of cropping systems on the production and chemical and biological properties of soil. Rice-potato-mungbean cropping system gave 59-89% higher productivity, 30-46% higher protein yield, 18-38% higher energy output and resulted in 7-16% higher available P, 60% higher fungi population, 15% higher actinomycetes population, 14% higher microbial biomass and 3% higher CO2 evolution in soil than rice-wheat cropping system. Rice-rapeseed-mungbean cropping system also gave 12-15% higher productivity, 19-26% higher protein yield and resulted in 11-18% higher available P, 65% higher fungi population, 22% higher actinomycetes population, 12% higher microbial biomass and 2% higher CO2 evolution in soil than rice-wheat cropping system. However, the rice-potato-mungbean cropping system was significantly superior to the rice-rapeseed-mungbean cropping system in productivity, protein yield and energy output and thus recommended as in alternative to rice-wheat cropping system. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A field study conducted for two crop cycles of five cropping systems supplied with six nutrient combinations at the Indian Agricultural Research Institute, New Delhi indicated that the cropping systems having a legume increased organic C content over initial level by 0.02-0.05%, available N by 3.5-14.1 kg ha-1, whereas the rice-wheat cropping system resulted in a reduction in organic C and available N over initial level by 0.05% and 1.5 kg ha-1, respectively after 2 years of study. Rice-potato-mungbean cropping system resulted in a negative balance of available P and rice-clover cropping system had a negative balance of both available P and available K content in soil and thus call for adequate P and K fertilization. Application of P and K helped in building up their content in soil; NPK + FYM showed the highest increase in organic C, available N, available P and available K content in soil. These results suggest the inclusion of a legume in a cropping system for maintaining organic C and available N in soil and adequate P and K fertilization for arresting the depletion of available P and K content in soil. Integrated nutrient management is one of the best methods for resilience of soil fertility under rice-wheat cropping system. [ABSTRACT FROM AUTHOR]