Characteristics of the microbial communities regulate soil multifunctionality under different cover crop amendments in Ultisol

The use of cover crops is a promising strategy for influencing the soil microbial consortium, which is essential for the delivery of multiple soil functions (i.e., soil multifunctionality). Nonetheless, relatively little is known about the role of the soil microbial consortium in mediating soil multifunctionality under different cover crop amendments in dryland Ultisols. Here, we assessed the multifunctionality of soils subjected to four cover crop amendments (control, non-amended treatment; RD, radish monoculture; HV, hairy vetch monoculture; and RDHV, radish–hairy vetch mixture), and we investigated the contributions of soil microbial richness, network complexity, and ecological clusters to soil multifunctionality. Our results demonstrated that cover crops whose chemical composition differed from that of the main plant crop promoted higher multifunctionality, and the radish–hairy vetch mixture rendered the highest enhancement. We obtained evidence that changes in soil microbial richness and network complexity triggered by the cover crops were associated with higher soil multifunctionality. Specifically, specialized microbes in a key ecological cluster (ecological cluster 2) of the soil microbial network were particularly important for maintaining soil multifunctionality. Our results highlight the importance of cover crop-induced variations in functionally important taxa for promoting the soil multifunctionality of dryland Ultisols.