Climate change mitigation in rice fields: A global synthesis of agronomic interventions

Rice sustains half the global population, yet its cultivation is a major source of greenhouse gas (GHG) emissions. Meeting rising demand calls for agronomic interventions that increase yields while curbing GHG emissions. Here, for the first time, we present a meta-synthesis of 91 meta-analyses, quantifying the effects of 54 rice agronomic interventions, grouped into 14 categories, on yield, CH₄ and N₂O emissions, global warming potential (GWP), and GHG emission intensity (GHGI). Biochar consistently delivered co-benefits, increasing yield by 12%, and reducing CH₄, N₂O, and GHGI by 15-18%. In contrast, residue incorporation and organic amendment raised yields (5% and 19%), but sharply increased CH₄ emissions (144% and 76%) and GWP (96% and 65%). No-till or reduced tillage lowered GWP by 15% without a yield penalty. Water-saving technologies cut CH₄ emissions by 50% and GHGI by 39%, with a slight yield decline (-3%). Within this category, intermittent irrigation offered the best balance, while non-flooded systems achieved greater emission reductions but incurred larger yield losses (-9%). Inorganic nitrogen fertilizer increased yields by 31% but raised N₂O emissions by 130%. Innovations, including deep placement and enhanced-efficiency fertilizers, reduced N₂O emissions by up to 38% and improved yields by 6%-19%. Symbiotic systems (e.g., rice-duck) reduced CH₄, though effects on N₂O were variable. While several agronomic interventions show promise, evidence remains limited for others (e.g., liming, crop establishment, weed management). Assessment of integrated approaches is needed to elucidate synergies and trade-offs, enabling the design of scalable, sustainable rice systems tailored to diverse contexts.