Degradation-Resistant Biochar Improves Soil Organic Carbon Storage: Promoting Autotrophic Metabolism & Increasing Refractory Organic Carbon

Abstract

Biochar, as a soil amendment to enhance soil carbon sink, is a dual-effect carbon neutralization technology. However, the dissolved solids released from biochar not only shorten the duration of carbon sequestration but also diminish its efficacy on improving soil carbon fixation. In this study, biochar prepared from cellulase-treated lignocellulose (BC-SR) was utilized to address the defect. After one year, BC-SR promoted a net increase of 4.39 mg C/g in soil (equivalent to fixing 16.10 mg CO₂/g), which was 28 % higher than ordinary biochar. The role of BC-SR was primarily achieved by three aspects: (1) Enhance microbial autotrophic metabolism; (2) Promote the formation of soil macroaggregates to protect easily degradable organic carbon; (3) Increase the proportion of refractory organic matter. This study demonstrated that compared with ordinary biochar, BC-SR exerted a stronger effect on autotrophic metabolism, and the newly generated organic matter persisted in the soil for a longer time.