Life cycle greenhouse gas emissions from five contrasting rice production systems in the tropics

Abstract

Carbon Footprints (CFs) quantification of major rice production systems (RPSs) is a prerequisite for chalking out strategies for climate change mitigation in agriculture. Total life cycle greenhouse gas emissions (LC-GHGs) from production to consumption could provide precise CFs for RPSs. Therefore, to address this issue, we assessed all the three segments of LC-GHGs for five major contrasting RPSs in India, such as, aerobic rice (AR), shallow lowland rice (SLR), system of rice intensification (SRI), deep water rice (DWR), and zero-tilled direct-seeded rice (ZTR)) to determine the CFs. The CF was found to be lowest in ZTR but the LC-GHGs were found to be lowest in case of AR, which recorded higher CF than that of ZTR. So, for short-term reduction of greenhouse gas (GHG) emission, aerobic rice (AR) is a good option. However, ZTR with lowest CF among all, could be prompted with incentives for long-term strategy. Among the segmental LC-GHGs, the ‘on-farm’ emission contributed less compared to the other two segments. The post-harvest to consumption segment contributed the maximum (54%–69%) of total LC-GHGs, followed by ‘cradle-to-farm’ (21%–27%), and on-farm operations (11%–23%). These findings suggest that post-harvest components that contribute maximum GHG emissions must be tackled scientifically with proactive policy initiatives. However, the data on this segment is limited and scattered. Therefore, real-time assessment of GHG emissions during post-harvest activities and transportation of inputs from cradle to farm require more precise quantification. Although the CF in SRI was found to be more, yet this system has the potential to fetch higher yields and better soil carbon storage. So, SRI could be encouraged for food security and long-term sustainability perspectives by reducing greenhouse gas emissions by 3-to-4 times.