Reducing the Accumulation of Antibiotic Resistance Genes (ARGs) in Soil Through Organic Manure Amendment Combined with Mineral Drip Fertigation in a Semi-Arid Region

Combining basal organic manure amendment with mineral drip fertigation sustains soil productivity in water-limited agroecosystems, yet its complex impact on the accumulation risks of antibiotic resistance genes (ARGs) requires careful evaluation. However, the distribution, dissemination, and driving mechanisms of soil ARGs remain unclear. Based on high-throughput sequencing and high-throughput quantitative PCR (HT-qPCR) techniques, this study evaluated six fertilization regimes within a semi-arid maize field: no fertilization (CK), organic fertilizer alone (OM), mineral fertilizer alone (CF), integrated organic-mineral fertilization (CF+OM), drip fertigation with mineral fertilizer (FDI), and organic fertilization combined with mineral drip fertigation (FDI+OM). We targeted specific ARGs (tetracyclines, aminoglycosides, and multidrug resistance) due to their agricultural prevalence and high clinical risks. FDI+OM significantly enhanced bacterial abundance and diversity, whilst the fertilization regimes significantly altered bacterial community structure, with dissolved organic carbon (DOC) as the primary factor. Compared with CF and FDI, the application of organic fertilizer (OM, CF+OM, FDI+OM) significantly increased ARG diversity and abundance; in contrast to conventional fertilization (CF, OM, CF+OM), drip fertigation (FDI, FDI+OM) significantly reduced ARG abundance. Organic carbon pools indirectly affect ARG loads via altering bacterial abundance and further mediating the abundance of mobile genetic elements (MGEs). In summary, the combined application of organic fertilizer can increase soil carbon storage and microbial diversity, but may also increase the load of ARGs, whereas combining it with mineral drip irrigation fertilization helps reduce the accumulation of ARGs.