Effect of soil manipulation and resource management on carbon and nitrogen turnover under rice-wheat cropping system

Field and laboratory studies were carried out at the IARI Farm, New Delhi to evaluate the impact of three factors, viz. tillage, water and integrated nutrient management (INM) on some biological indicators of soil quality under rice-wheat system. The objective was to monitor the carbon and nitrogen mineralization kinetics induced by soil microbial biomass under influence of different soil management practices. Two tillage practices, three water regimes and six nutrient treatments were applied to the rice-wheat system in a split-split plot design. The field experiment revealed that the most sensitive indicator, i.e. microbial biomass carbon (MBC), and soil organic carbon (SOC) responded positively to application of organics (farmyard manure, Leucaena leucocephala and rice residues) in conjunction with inorganics to the soil. Both SOC and MBC contents were higher where higher amount of irrigation water was applied to both rice and wheat. Carbon and nitrogen mineralization studies also revealed that application of FYM and Leucaena along with inorganics were better in terms of both carbon build-up and sustained release of nitrogen to the crops.