Biochar loss from rice paddies: A bottomless pit for carbon sequestration?

The application of biochar (BC) in rice paddies holds great potential for sequestering atmospheric carbon dioxide (CO 2 ).However, the efficiency of BC in enhancing soil organic carbon (SOC) may be lower than expected due to potential BC loss.In this study, we propose several mechanisms and pathways of potential BC loss, including wind erosion during application, water erosion post-application, the downward migration of fine BC particles following physical disintegration, and microbial mineralization to CO 2 .Despite these potential pathways, our understanding of the fate of applied BC in rice fields remains limited.Therefore, it is crucial to investigate BC dynamics under actual rice cultivation conditions.We suggest that using 13 C-labeled BC is the most feasible approach for tracing its fate.Furthermore, to mitigate BC loss via wind and water erosion, it is necessary to increase the sedimentation of BC by modifying its pore structure, thereby increasing its envelope density.