Fungicide-induced shifts in soil microbial and enzyme activity

Soil microbial communities are key indicators of biogeochemical processes; however, their response to fungicides across various agro-management systems remains underexplored. This study assessed the impact of carbendazim and iprodione, applied at both recommended and elevated doses, on bacterial community composition, enzymatic activities, and predictive functional profiles in Typic Haplustoll soils under conventional monoculture and conservation crop rotation systems. High-throughput 16S rRNA gene sequencing, enzymatic assays (ß-glucuronidase, ß-glucosidase, xylanase), and functional inference using Tax4Fun2 demonstrated that iprodione induced greater shifts in bacterial diversity and community structure, resulting in significant reductions in Proteobacteria and Acidobacteria, along with increases in Firmicutes. Enzymatic activity faced more severe inhibition from carbendazim, particularly within monoculture settings. Functional predictions indicated that iprodione suppressed pathways related to amino acid and carbohydrate metabolism, energy production, and nitrogen cycling genes (nirK, nosZ), while carbendazim exhibited milder effects. Although crop rotation alleviated some negative impacts, both fungicides altered critical microbial functions. These findings underline the necessity of implementing refined management strategies to preserve soil microbiological integrity and maintain agroecosystem functionality.