How System for Rice Intensification (SRI) mitigates greenhouse gas emissions
Rice Intensification (SRI) management contributes to mitigation objectives by decreasing the emissions of greenhouse gases (GHG) when continuous flooding of paddy soils is stopped and other rice-growing practices are changed.
- Methane (CH4) is reduced between 22% and 64% as intermittent irrigation (or alternate wetting and drying, AWD) means that soils have more time under aerobic conditions (Gathorne-Hardy et al. 2013, 2016; Choi et al. 2015; Jain et al. 2014; Suryavanshi et al. 2013; Wang 2006; Dill et al. 2013).
- Nitrous oxide (N2O) emissions increase only slightly with SRI or sometimes decrease as the use of N fertilizers is reduced. No studies so far have shown N2O increases offsetting the gains from CH4 reduction (Kumar et al. 2007; Visalakshmi et al. 2014; Vermeulen et al. 2012; Gathorne-Hardy et al. 2013, 2016; Choi et al. 2015).
- Total global warming potential (GWP) from rice paddies was reduced with SRI methods in the above studies by 20-30%, and up to 73% in one of the studies (Choi et al. 2015).
- Rice production’s carbon footprint is reduced to the extent that less fertilizer and fewer agrochemicals are used. GHG emissions from producing, distributing and using these inputs equal about 5-10% of the global warming potential (GWP) from all direct emissions from food production (Vermeulen et al. 2012). GHG emission studies with SRI are still in the early stages, and more detailed studies are needed to better link and understand how individual practices contribute to increasing or reducing GHG emissions. However, the mitigation potential of alternate wetting and drying, a component of SRI, is well established (Richards and Sander 2014).