Rotary Tillage Combined with Reducing Nitrogen Application Decreased Greenhouse Gas Emission from Rice Fields in South China

Rice yield and greenhouse gas (GHG) emission were investigated under different tillage and nitrogen treatments to obtain the suitable mode in increasing rice yield and reducing GHG emission from rice fields. The field experiments with four tillage methods (micro tillage C as CK, no tillage T, rotary tillage R, smash ridging tillage S) and two nitrogen rates (conventional nitrogen rate N1, 225 kg ha−1; reducing nitrogen rate N2, 150 kg ha−1) were conducted during 2021–2022 seasons to measure the rice yield and methane (CH4) and nitrous oxide (N2O) fluxes in rice fields using the static chamber-GC method, and then global warming potential (GWP) and GHG emission intensity (GHGI) were calculated. (1) RN2 had higher rice yield and was 9.9–12.7% higher than CN2. (2) RN2 had the lowest total CH4 emission and was 27.6–66.0% lower than other treatments. (3) RN2 had lower total N2O emission and was 20.1–21.1% lower than CN2. (4) The GWP and GHGI in RN2 were the lowest, and were 27.4–65.6% and 27.2–64.3% lower than other treatments, respectively. Rotary tillage combined with reducing nitrogen application can increase the rice yield, but decrease the greenhouse gas emission in rice fields.