Integrated water–carbon management reshapes trade-offs among greenhouse gas emissions, productivity, and economic returns in rice systems

CONTEXT Sustainable intensification of rice systems is hindered by the trade-off where organic inputs enhance fertility but stimulate greenhouse gas (GHG) emissions. OBJECTIVE We aimed to: (1) globally synthesize how irrigation modulates carbon-driven GHG trade-offs, and (2) evaluate management strategies that decouple agronomic returns from climate penalties. METHODS We combined a targeted meta-analysis of 39 field studies with a three-year factorial field experiment. We evaluated field-scale climate, production, water-use, soil‑carbon, and economic outcomes. Net ecosystem economic benefit (NEEB) accounted for grain income, agronomic costs, and the monetized net GHG balance, including seasonal methane (CH 4 ) and nitrous oxide (N 2 O) emissions expressed as CO 2 equivalents and the estimated soil organic carbon (SOC)-change term. RESULTS AND CONCLUSIONS The meta-analysis revealed substantial heterogeneity in irrigation-mediated CH 4 responses to organic amendments, with no consistent attenuation under water-saving irrigation (WSI). In the field experiment, relative to the corresponding flood irrigation (FI) treatments, controlled irrigation (CI) reduced seasonal CH 4 emissions by 34–55% and net GHG emissions by 23–49%, but increased N 2 O emissions. Furthermore, while all organic amendments enhanced SOC, yield, and NEEB, their climate impacts diverged. Straw incorporation amplified CH 4 emissions, whereas manure substitution reduced N 2 O emissions compared with synthetic fertilization. Among the treatments evaluated, CI-Manure showed the most consistent balance by maintaining relatively high yield and economic return while reducing NGHGE and irrigation input relative to FI-Fert. SIGNIFICANCE These findings identify conditions under which coordinated irrigation and amendment management may improve field-scale climate and production outcomes in irrigated rice systems with reliable water control and locally available organic resources.