Water management and soil amendment for reducing emission factor and global warming potential but improving rice yield

Alternate wetting and drying (AWD) for growing rice improves water productivity (WP), minimize methane emission and net ecosystem carbon balance (CO2), but might be responsible for increased nitrous oxide emissions. The combined effects of water management and different organic manure application on methane emission, carbon dioxide and nitrous oxide fluxes, emission factor (EF) and WP are not well documented, which has been evaluated during dry seasons of 2018 and 2019. AWD and continuous flooding (CF) were imposed in NPKSZn, cowdung (CD), poultry manure (PM) and vermicompost (VC) treated plots. Closed chamber techniques were used for determining emissions of greenhouse gases. In comparison with CF, the AWD significantly reduced total GWP by 15-44% depending on soil amendments and 2-29% net ecosystem carbon balance (CO2); but additional N2O contribution to GWP was about 0.61-1.18% compared to sole chemical fertilizer treatments. Depending on soil amendments, the AWD reduced EF of CH4 (22-36%) but increased WP by 25-27% compared to CF system along with 14-43% reduction in GHG intensity (GHGI). Vermicompost treatment had the lowest GHG emission, GWP, EF and GHGI than cowdung, poultry manure under both irrigation methods. Rice yield varied because of soil amendments but not with irrigation methods. Use of vermicompost improved soil organic carbon (SOC) storage significantly than cowdung and poultry manure. In conclusion, AWD practice and amendment of rice soil with vermicompost could be an effective strategy for reducing GHG emission, GWP, EF and GHGI without sacrificing rice yield.

Automated summary

AWD for rice cultivation can reduce methane and CO2 emissions but may increase N2O emissions. Different organic manure applications can affect greenhouse gas emissions and water productivity.