QUAntifying ricE gReenhouse gas Emissions (QUAERE): Mitigation Potential of Sustainable Irrigation Practice in India

The case for mitigating greenhouse gas emissions from rice production systems is well recognised. Among different strategies, alternate wetting and drying (AWD) has emerged as a low-tech, water-saving approach with strong emission mitigation potential. Intermittent drying of rice fields creates an aerobic environment that suppress methane production. We present a multi-season, landscape-scale assessment of AWD in intensive rice cultivation systems of Telangana state in Southern India. Using a robust experimental design, we quantified irrigation water use, crop productivity, and methane emissions, measuring methane fluxes with static closed chambers. Across seasons, AWD consistently lowered methane emissions relative to conventional continuously flooded systems while maintaining grain and biomass yield. Irrigation demand was reduced under AWD, with water savings ranging from ~14% to ~37%. When conservatively scaled, emission reductions correspond to mitigation potentials of 2.5-3.5 Mt CO2-eq ha-1 season-1. These observations enabled the calibration and validation of process-based biogeochemical crop models, which were subsequently extrapolated to the project region using a remote-sensing-based framework. Overall, this work highlights AWD as a scalable lever for reducing emissions, conserving water and improving regional inventories, while strengthening voluntary carbon market accounting and sustainability assessments in rice production systems.