Green manure (Raphanus stativus L.) alters soil microbial structure and promotes acetochlor degradation

Microorganisms play important roles in the remediation of contaminated soil. However, the relationship between the soil microbial communities and herbicide degradation remains unclear after applying green manure. The aim of this study was to investigate the effect of green manure on soil physicochemical properties, between acetochlor degradation and microbial communities. Adoption of pot experiments, the effects and mechanism of four fertilization treatments (CK: without green manure; GMV: Vicia villosa Roth; GML: Lolium perenne L.; GMR: Raphanus stativus L.) on the degradation of acetochlor were evaluated. Appling to Raphanus stativus L., acetochlor degraded in 5.82 days, which was 74.81 % higher than that of CK. Community differences in soil microbes were analysed using high-throughput sequencing. The predominant phyla of fungi were Ascomyocta, Mortierellomycota, Basidiomycota, unclassified_k_Fungi, and Chytridiomycota, which accounted for 85.01 %–116.46 % of the fungal OTUs. The green manure treatment showed higher abundance of Mortierella (9.54 %–13.05 %), diversity of saprotrophic fungi and symbiotic fungi and faster rate of degradation of acetochlor as compared to CK. In addition, soil properties such as soil total phosphorus (TP) and pH have significant effects on microorganisms. Fungal functional analysis revealed that the microorganisms associated with acetochlor biodegradation mainly belonged to Ascomycota and Glomeromycota. This study offers new insights into the relationship between soil properties and the environmental risks associated with the presence of pesticides in soil and the related mechanisms.