Organic Amendments for Simultaneous Soil Carbon Sequestration and Soil-Borne Pathogen Suppression: Mechanisms and Perspectives

The depletion of soil organic carbon (SOC) and the escalating prevalence of soil-borne plant pathogens represent critical challenges to terrestrial biogeochemical stability and global food security. With approximately 24% of terrestrial carbon reserves lost and over US$220 billion in annual crop losses attributed to soil-borne diseases, understanding biotic and geochemical controls on soil health is essential. This review evaluates the dual functionality of organic amendments (agricultural residues, animal manures, and urban biosolids) as drivers of simultaneous carbon restoration and pathogen suppression. We analyze the mechanisms governing these benefits, focusing on the biogeochemical coupling of element cycles and microbiome-mediated processes such as the formation of recalcitrant carbon, organo-mineral protection, and microbial carbon use efficiency (CUE). Biochar applications can increase SOC stocks by 26–33% (11.5–14.6 Mg ha⁻¹), while silicon-modified biochar reduces the bacterial wilt index caused by Ralstonia solanacearum by 73.4%. Furthermore, we examine the geochemical mechanisms of pathogen suppression through antibiosis, resource competition, and signaling disruption. Comparative analysis reveals that while composts facilitate broad-spectrum biological antagonism, engineered biochar provide superior long-term carbon stability and biocontrol selectivity. However, the synthesis of biogeochemical monitoring data remains fragmented due to non-standardized evaluation protocols. We propose that advancing precision amendment engineering and establishing standardized monitoring frameworks will be essential for quantifying carbon sequestration at global scales and elucidating the mechanisms driving patterns in biogeochemical cycles. Integrating these data into ecosystem management is vital for enhancing agroecosystem resilience and achieving global sustainability targets.