The Positive Effect of Biochar on Rice Growth Increases Methanotrophs to Mitigate Methane Emissions: A Meta‐Analysis

ABSTRACT Rice paddies are a major source of methane (CH 4 ), and effective mitigation strategies are urgently needed. Biochar has been proposed as a promising option; however, quantitative effects on CH 4 ‐cycling microbial processes and their underlying mechanisms remain unclear. Here, we conducted a meta‐analysis and a random‐effects model to evaluate the effects of biochar on CH 4 emissions, crop yield, and key microbial functional genes and soil properties, drawing primarily on studies conducted in China. Overall, biochar application reduced CH 4 emissions by 26.4% and increased rice yield by 6.2%. These responses were associated with enhanced plant biomass, which suppressed methanogen activity while stimulating methanotrophs, likely mediated by increased root oxygen release and rhizosphere carbon availability. Notably, the decreased mcrA / pmoA ratio highlighted a shift in microbial functional balance favoring CH 4 mitigation. Our study provides a more comprehensive synthesis by linking biochar‐induced changes in microbial functional genes to CH 4 mitigation and crop productivity. These findings offer quantitative evidence and practical guidance for biochar application in climate‐smart and sustainable rice cultivation.