Quantifying the global methane mitigation potential of deep nitrogen placement in rice paddies

• The effectiveness of deep nitrogen (N) placement in reducing CH 4 emissions increases with higher N application rates. • Deep N placement reduces organic matter decomposition and soil mcrA gene abundance under high N application rates. • Deep N placement could potentially reduce CH 4 emissions from global rice paddies by 14.6 %. Rice paddies are major sources of methane (CH₄), a potent greenhouse gas, with emissions influenced by soil nitrogen (N) availability. Deep nitrogen placement (DN) is emerging as a promising strategy to improve rice yields, N use efficiency, while also impacting CH₄ emissions. However, the variability in DN's effects on CH₄ emissions complicates the extrapolation of experimental results to broader geographical regions. This study, combining meta-analysis and experiments, identifies N application rate as a key factor in DN's impact on CH₄ emissions. DN is more effective at CH₄ emission mitigation with higher N application rates, mainly through reducing organic matter decomposition and suppressing soil mcrA gene abundance. We estimate that DN could lower CH₄ emissions from global rice paddies by 14.6 %. These findings underscore the potential of DN to mitigate CH₄ emissions on a global scale while enhancing rice yields and N efficiency, particularly in regions with high N application rates.