Maximizing nitrous oxide mitigation potential of straw-derived biochar in China with optimal application strategies

Abstract Agricultural soils are a significant source of nitrous oxide (N 2 O) emissions. The application of biochar to soil offers a synergistic approach to establishing stable organic carbon (C) storage while reducing greenhouse gas (GHG) emissions, particularly through effective reductions in N 2 O emissions. However, current biochar application strategies often lack consideration of locally tailored application rates and biochar properties, limiting its N 2 O mitigation potential. Here, we conduct a spatially explicit analysis to investigate the N 2 O mitigation potential of straw-derived biochar in China’s croplands, exploring optimal application strategies under both ideal and realistic conditions. The key drivers that influence the spatial patterns of straw-derived biochar’s mitigation potential and application strategies are also revealed. We find that applying biochar with optimal strategies could avoid approximately 50% and 36% of nationwide cropland N 2 O emissions under ideal and realistic conditions, respectively. The optimal biochar application rate and properties required to achieve the maximum N 2 O reduction potential exhibit significant spatial variability, differing among biochar types. Key factors determining the optimal biochar application rate in various regions include N fertilizer application rates and soil organic carbon (SOC) content, while water input—including precipitation and irrigation water input—is the primary factor determining the optimal biochar properties. These findings may inform the development of site-specific biochar application strategies aimed at enhancing the N 2 O mitigation efficacy in croplands across China. Graphical Abstract