A study explores how microbially driven iron cycling enhances organic carbon accumulation in biochar-amended soils over decades. Biochar, a carbon-rich material derived from organic matter, has shown potential in increasing soil organic carbon (SOC) and reducing CO₂ emissions. The research found that biochar amendment led to a 2-fold increase in SOC over a decade and reduced CO₂ emissions by about 11% during a 56-day incubation. This effect was attributed to biochar facilitating iron reduction and subsequent Fenton-like reactions, which may enhance microbial extracellular electron transfer and carbon utilization efficiency. The study also showed that mineral-associated organic matter (MAOM) and biochar particles contribute to microbial carbon accumulation and plant debris preservation. Soil slurry experiments confirmed the role of microbes in hydroxyl radical generation and biotic carbon sequestration in biochar-amended soils. The findings highlight the intricate biotic and abiotic mechanisms governing carbon dynamics in long-term biochar-amended upland soils. The study underscores the importance of microbial activities in soil carbon cycling and the potential of biochar as a tool for carbon sequestration in agricultural soils.A study explores how microbially driven iron cycling enhances organic carbon accumulation in biochar-amended soils over decades. Biochar, a carbon-rich material derived from organic matter, has shown potential in increasing soil organic carbon (SOC) and reducing CO₂ emissions. The research found that biochar amendment led to a 2-fold increase in SOC over a decade and reduced CO₂ emissions by about 11% during a 56-day incubation. This effect was attributed to biochar facilitating iron reduction and subsequent Fenton-like reactions, which may enhance microbial extracellular electron transfer and carbon utilization efficiency. The study also showed that mineral-associated organic matter (MAOM) and biochar particles contribute to microbial carbon accumulation and plant debris preservation. Soil slurry experiments confirmed the role of microbes in hydroxyl radical generation and biotic carbon sequestration in biochar-amended soils. The findings highlight the intricate biotic and abiotic mechanisms governing carbon dynamics in long-term biochar-amended upland soils. The study underscores the importance of microbial activities in soil carbon cycling and the potential of biochar as a tool for carbon sequestration in agricultural soils.