Potential and promisingness of technical options for mitigating greenhouse gas emissions from rice cultivation in Southeast Asian countries
Paddy fields are considered as one of the most important sources of anthropogenic methane (CH4) and nitrous oxide (N2O) emissions. While several technical options have been proposed to reduce these emissions, gaps in data and information based on application of these options in the field are a key barrier to scaling-up. To address these gaps, we conducted a review of literature to analyze the potential of technical options in Southeast Asia (SEA). Using screening criteria based on reliability of experimental data, 31 region-specific cases were selected for the analysis. A meta-analysis indicated that water management options, including single and multiple drainage approaches such as alternative wetting and drying (AWD), significantly reduced CH4 emissions by 35% as a mean effect size (95% confidential interval: 41–29%), as well as the combined effects of CH4+N2O (net GWP) by 29% (36–23%). The effect on reducing CH4 emissions in the dry season was significantly larger than that in the wet season. Application of biochar reduced both CH4 and N2O emissions by 20% (40% to −7%), while significantly increased rice yield by 28% (8–52%). Other options such as removal of rice straw from the previous crop, composting rice straw and manure, application of sulfate-containing fertilizer, and soil drying in the fallow season also have recognized potential to reduce emissions but require further data and consideration of possible trade-offs. Based on the analysis of mitigation potential, promising technical options were assessed by considering together with constraints and additional co-benefits in order to provide a useful guide for policy makers and rice value chain operators in SEA countries for adopting mitigation options in rice cultivation to tackle climate change and enhance agriculture sector sustainability.
