Long-Term Straw Return Reverses Antibiotic Resistance Accumulation in Maize Rhizosphere through Integrated Soil-Microbial Mechanisms

The impact of long-term agricultural cultivation on antibiotic resistance has emerged as a critical environmental concern. However, previous studies have primarily examined organic fertilizers, and the effects of sustained chemical fertilizer use combined with straw incorporation over extended periods remain poorly understood. Here, we employed a 25-year field trial combined with metagenomic analysis to investigate the differential effects of chemical fertilization and straw incorporation on soil antibiotic resistance gene (ARG) dynamics in the maize rhizosphere. Results showed that long-term cultivation progressively increased ARG and virulence factor gene (VFG) abundance. Metagenomic analyses suggested that shifts in Pseudomonas populations and microbial metabolic pathways were associated with elevated levels of ARGs in the rhizosphere. Field inoculation with a synthetic Pseudomonas community further increased the ARG abundance, accompanied by reduced genomic GC content and enrichment of specific metabolic pathways. In contrast, straw amendment treatments reduced Pseudomonas abundance and soil acidification while increasing the soil total carbon and lignin degradation functional capacity. Our findings indicate that long-term straw incorporation represents a promising strategy for controlling antibiotic resistance dissemination in agricultural systems, offering valuable insights into sustainable crop management practices.