Organic Fertilization Mitigates Long-Acting Herbicide Mesosulfuron-Methyl Effects via Rhizosphere Soil Bacterial Community Regulation in Wheat

Mesosulfuron-methyl is a long-residual herbicide widely used in wheat fields. This study demonstrates that organic fertilizer application accelerates its degradation by reshaping the rhizosphere bacterial community. 16S rRNA sequencing showed fertilization consistently enriched multiple sulfonylurea-degrading taxa (e.g., Rhodococcus, Streptomyces, Sphingomonas, Pseudomonas) across various growth stages. Notably, the abundance of taxa such as Rhodococcus, Streptomyces, and Microbacterium was negatively correlated with herbicide residues. These microbes dominated during seedling and jointing stages, coinciding with rapid herbicide degradation. Furthermore, soils amended with organic fertilizer formed more resilient microbial networks, with Sphingomonas as a keystone taxon. Structural equation modeling identified Sphingomonas, Pseudomonas, and community diversity as key degradation drivers. Tax4Fun analysis indicated increased abundances of monooxygenase, dioxygenase, carboxylesterase, and hydrolase. Organic fertilization thus promotes beneficial bacterial communities that enhance pesticide degradation, thereby improving soil health in wheat systems.