Abstract

Rice is a staple food for much of the global population, but its traditional cultivation methods, particularly prolonged flooding, contribute to significant methane (CH₄) emissions. Introducing a rice-maize rotation system has the potential to reduce greenhouse gas (GHG) emissions. This study compared double-cropping rice fields with rice-maize rotation systems, with and without tillage, over two consecutive growing periods. The closed chamber method was employed to measure carbon dioxide (CO₂) and CH₄ fluxes in each field, assessing GHG emissions across different cropping systems. Results indicate that tillage is an effective management practice for reducing emissions in double-cropping rice systems. The total net carbon absorption (CO₂ + CH₄) over two periods ranked as follows: double-cropping rice in field A (AR1-AR2) at 4.93 t C/ha > rice-no-tilled maize in field B (BR1-BNTC2) at 3.46 t C/ha > rice-till maize in field B (BR1-BTC2) at 3.41 t C/ha > rice-no-till maize in field C (CR1-CNTC2) at 2.24 t C/ha > rice-tilled maize in field C (CR1-CTC2) at 1.79 t C/ha. The global warming potential (GWP) of the rice-maize rotation systems was notably lower than that of double-cropping rice, primarily due to the high CH₄ emissions from waterlogged conditions in control fields. Among treatments, the rice-no-till maize system exhibited the lowest GWP and greenhouse gas intensity (GHGI) while also achieving the highest crop yield, implying it the most environmentally and economically sustainable option.

Keyword: Greenhouse gas emissions, greenhouse gas intensity, global warming potential, climate-smart agriculture