Insights into the changes of soil microorganism communities and carbon cycle metabolic functions caused by the application of L-glufosinate-ammonium
L-glufosinate-ammonium (L-GLA), a widely used herbicide, exerts detrimental non-target effects on crops, soil microorganisms, and ecosystems. However, its impacts on soil microbial communities and metabolic functions remain poorly understood. In this study, we applied L-GLA at two concentrations—600 g a.i. hm−2 (low, L) and 3,000 g a.i. hm−2 (high, H)—to yellow-brown soil and investigated its effects on microbial community composition, carbon cycle-related metabolic functions, and soil metabolites using integrated metagenomics and soil environmental pseudotargeted metabolomics at 30 and 60 days post-application. The degradation rate of L-GLA was concentration-dependent, with half-lives of 18.8 days (L) and 29.7 days (H). Both doses significantly reduced soil organic matter (SOM) and available potassium (AK) content, and markedly altered microbial community richness, structure, and composition. L-GLA exposure also disrupted the complexity of soil microbial co-occurrence networks and the activities of carbon-cycle-related enzymes. Metabolomic analysis further revealed significant (p < 0.05) and dose-dependent alterations in the soil metabolite profile. Correlation analysis indicated strong associations between characteristic microbial taxa and differential metabolites. Our findings provided critical insights into how L-GLA influences the soil microecological environment and contributed to a deeper understanding of soil microbial ecology in the context of modern agricultural practices.