Rice cultivation plays a pivotal role in global food security but remains a major source of greenhouse gas (GHG) emissions, particularly methane (CH 4 ) and nitrous oxide (N 2 O). To tackle this, several researchers have shown the potential of biochar, a carbon-rich material derived from biomass pyrolysis, in lowering emissions, optimizing yield emission trade-offs, and enhancing soil health. However, most of these studies are highly region and context-specific. Therefore, a robust and comprehensive, global-scale investigation is important to quantify the actual impact of biochar on rice yield, emission trade-offs, and soil health. This meta-analysis systematically evaluated the effects of biochar application on GHG emissions, global warming potential (GWP), greenhouse gas intensity (GHGI), total soil carbon stock response (TSCSR), and rice yield. From an initial pool of 27,000 publications, 54 studies were selected based on strict inclusion criteria, contributing a total of 1,143 paired observations: 197 for CH 4 , 164 for N 2 O, 176 for GWP, 176 for GHGI, 336 for grain yield, and 94 for TSCSR. On average, biochar application was associated with reductions in CH 4 (18.11%) and N 2 O (15.54%) emissions, along with decreases in GWP (25.51%) and GHGI (33.16%). Additionally, TSCSR increased by 69.96%, and rice yield increased by 11.13%. However, the increase in TSCSR may, to some extent, reflect the direct contribution of biochar-derived carbon, along with changes in native soil organic carbon. The magnitude of these responses varied across climatic conditions, soil properties, management practices, and biochar properties. Subtropical regions showed consistent reductions across all variables, whereas tropical regions exhibited the strongest reductions in integrated indices (GWP and GHGI). Across soil textures, emission reductions (CH 4 , GWP, and GHGI) were more pronounced in coarse-textured soils, while yield and TSCSR responses were greater in fine-textured soils. Stronger responses were also observed in acidic soils with moderate organic carbon and low total nitrogen. Additionally, biochar produced from high C:N ratio feedstocks, with an acidic pH, and generated at lower pyrolysis temperatures (<650°C), showed a comparatively stronger response. Although puddled transplanted rice systems with continuous flooding and high nitrogen inputs typically enhance CH 4 emissions, biochar application at moderate rates (10-30 t ha -1 ) was associated with reduced GHG emissions and improved productivity. These findings emphasize biochars potential to support sustainable rice production by reducing emissions and improving yield. Future efforts should focus on large-scale, long-term trials and incentivizing adoption through carbon credit frameworks to advance climate-resilient agriculture. • Biochar reduced CH₄, N₂O, GWP and GHGI by 18, 15, 25 yield gains were higher in fine-textured, acidic soils with moderate OC and low N • Biochar derived from high C:N feedstocks at low pyrolysis temperatures (˂650°C), with acidic pH proved most effective • Optimal emission mitigation and yield gains were observed in PTR, and moderate biochar application (10-30 t/ha) • The study identifies key characteristics for scaling biochar use in climate smart rice cultivation
Sinha et al. (2026) studied this question.