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) and minimize methane emission, but might be responsible for increased carbon dioxide and 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, cow dung, poultry manure and vermicompost treated plots. Closed chamber techniques were used for determining emissions of greenhouse gases. In comparison with CF, the AWD significantly reduced total GWP by 23-46% depending on soil amendments; but alleviated carbon dioxide and nitrous oxide fluxes by 5-6% and 39-46%, respectively. Depending on soil amendments, the AWD reduced EF of CH4 (28-56%) but increased WP by 34-35% compared to CF system along with 21-43% reduction in GHG intensity (GHGI). Vermicompost treatment had the lowest GHG emission, GWP, EF and GHGI than cow dung, poultry manure under both irrigation methods. Rice yield varied because of soil amendments but not with irrigation methods. The use of vermicompost improved soil organic carbon (SOC) storage significantly than cow dung 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.

Author(s): Md Mozammel Haque, Jatish C Biswas, M Maniruzzaman, M B Hossain and M R Islam

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