Strategies for controlling greenhouse gas emission from lowland rice fields: A review

Abstract

Rice is one of the most extensively cultivated crops worldwide; however, traditional paddy cultivation has raised significant environmental concerns, particularly the emission of greenhouse gases (GHGs), namely methane gas. According to FAOSTAT 2020, energy consumption in agriculture is around 0.9 Gt CO2-eq in 2018. Methane, a major GHG, is released into the atmosphere from rice fields through three primary pathways: diffusion, ebullition or rising bubbles and plant-mediated transport. Its production is primarily a microbially mediated anaerobic process, promoted by the flooded conditions typical of paddy systems. Methane emissions can vary considerably based on climatic factors such as air and soil temperature, as well as the season of cultivation. Rice fields emit GHGs even during fallow periods. Additionally, varietal differences among rice cultivars significantly influence methane release, with breeding efforts targeting low-emission varieties showing promising results. Agronomic practices, including alternate wetting and drying (AWD), optimized nutrient management and the incorporation of specific organic amendments, have been effective in reducing methane emissions from paddy fields. This review provides a comprehensive overview of greenhouse gas (GHG) emission especially methane, its production process or methanogenesis, emission pathways as well as the practical mitigation strategies to be adopted in lowland rice cultivation.