Abstract
Subtropical agricultural systems face dual challenges of enhancing soil carbon sequestration and mitigating greenhouse gas emissions, particularly nitrous oxide (N2O). This study investigated the efficacy of different biochar types (wood-derived and manure-derived) and application rates (5 t ha-1 and 10 t ha-1) in optimizing soil carbon accumulation and N2O mitigation in a typical subtropical agricultural soil over a two-year field experiment. Results showed that all biochar treatments significantly increased soil organic carbon (SOC) content compared to the control, with the 10 t ha-1 wood-derived biochar demonstrating the highest SOC increase (up to 18% over control). Concurrently, biochar amendments led to substantial reductions in cumulative N2O emissions, ranging from 25% to 55%, with the 10 t ha-1 manure-derived biochar showing the most pronounced mitigation. The observed effects were attributed to biochar's stable carbon structure, altered soil pH, enhanced microbial community shifts, and improved soil aeration. This research identifies optimal biochar strategies for dual climate benefits in subtropical agriculture, providing evidence-based insights for sustainable land management and climate policy development.
