Effects of crop rotation and tillage on CO2 and CH4 fluxes in paddy fields

Effects of crop rotation and tillage on CO2 and CH4 fluxes in paddy fields

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.