A life cycle assessment (LCA) of greenhouse gas emissions from SRI and flooded rice production in SE India

Abstract

Rice feeds more people than any other crop, but each kilogram of rice is responsible for substantially more greenhouse gas (GHG) emissions than other key staple foods. The System of Rice Intensification (SRI) has recently received considerable attention for its ability to increase yields while using less water. Yet so far there has been little research into the GHG emissions associated with SRI production systems, and how they compare to those from conventional flooded-rice production techniques. A streamlined Life Cycle Assessment (LCA) methodology was used to compare the GHG emissions and groundwater use from SRI and from conventional rice production. Input data were derived from farmer questionnaires in SE India and appropriate secondary data sources. The results showed that SRI methods substantially raised farmers' yields, from 4.8 tons to 7.6 ton per hectare, a 58% increase, while reducing water applications. At the same time it was seen that SRI management offered opportunities for significant GHG reductions, both per hectare and per kilogram of rice produced. These savings principally arise from reduced methane emissions and reduced embodied emissions in the electricity used to pump water for irrigation. SRI nitrous oxide emissions were somewhat higher than on control farms, but the difference was significant only per hectare, not per kg of rice. The net effects of SRI practice on reducing global warming potential were positive in that the small increases in N2O did not offset the larger diminishment of CH4.