Mitigating greenhouse gas and nitrogen loss with improved fertilizer management in rice: quantification and economic assessment

Several technologies have been developed to improve the recovery efficiency of N (RE_N) but their impacts on greenhouse gas (GHG) emission, N loss and economic implication are rarely analysed. A decision support system (DSS) has been developed to quantify inputs, outputs and balance of N in soil; GHG emission and RE_N with the prominent N management technologies in rice. This DSS, named InfoNitro (Information on Nitrogen Management Technologies in Rice), integrated analytical and expert knowledge with databases on bio-physical, agronomic and socio-economical features to establish input–output relationships related to N management in rice. Sixteen technologies, which differed in terms of water regime, method of N application, forms of N and tools of fertilizer recommendation were analysed for their RE_N, N losses, GHG emission and economic return in Haryana, a rice growing region in India. In the current farmers’ practice, RE_N was 32.7%, which increased up to 40.8% with various technologies except in mid-season drainage and alternate flooding technologies where it decreased up to 29.3%. Loss of N through leaching, volatilization and denitrification in the farmers’ practice (67.5 kg N ha⁻¹) decreased up to 40.5 kg N ha⁻¹ except in mid-season drainage and alternate flooding technologies where it increased. The technologies also reduced global warming potential (GWP) by 1 to 9%. However, the technologies except no tillage, mid-season drying and alternate flooding reduced the net income of the farmers. When the environmental cost (cost of N loss and GWP) was included net income with various technologies was either at par or more than the farmers’ practice. The marginal abatement cost of N loss was Rs. 8 to 134 kg⁻¹ N and for GWP was Rs. 766 to 4854 Mg⁻¹ CO₂ eq. Resource conserving technology was the most cost effective strategy to reduce N loss and GHG emission whereas integrated N management cost high for mitigating GHG emission.