Divergent mitigation mechanisms of soil antibiotic resistance genes by biochar from different agricultural wastes

Biochar, produced from agricultural waste, provides a sustainable solution for effective waste management and soil remediation. The potential and mechanisms of biochar derived from primary agricultural sources (plant residues and animal manure) to mitigate the antibiotic resistance genes (ARGs) pollution in agricultural soil remain unexplored. To address this, a 60-day microcosm experiment was conducted, applying biochar derived from either corn straw (B1) or chicken manure (B2) to sulfamethazine and tetracycline-contaminated soil. The results demonstrated that B1 had richer functional groups than B2. B1 increased soil pH (+1.63 %) and total carbon (+24.56 %), but it decreased the abundance of norank_Vicinamibacteraceae (−35.71 %) and Haliangium (−42.11 %), and inhibited the dissemination of tetM and tetW by 57.76 % and 39.17 %, respectively. Comparatively, B2 significantly increased soil dissolved organic carbon (+161.66 %) and decreased the abundance of potential ARGs hosts ( Acidibacter , −40.32 %), leading to reduced sul2 abundance (−33.47 %). Besides, B2 enhanced soil total nitrogen and bacterial diversity, and further reduced tetW abundance (−33.76 %). Overall, this study revealed divergent mechanisms and potential for mitigating soil ARGs transmission by biochar derived from corn straw and chicken manure. This study contributes to developing more effective strategies for managing ARGs in contaminated soil and mitigating their environmental risks.