Influence of Cover Crop Root Functional Traits on Sweet Potato Yield and Soil Microbial Communities

The symbiotic relationship between cover crops and soil microorganisms is closely linked to nutrient cycling and crop growth within agroecosystems. However, how cover crops with different root functional traits influence soil microbial communities, soil properties, and crop yields has remained understudied. This study assessed the root traits of hairy vetch (HV) and rapeseed (RP), along with soil properties, sweet potato yield, and microbial enzyme activity under red soil dryland conditions. High-throughput sequencing was also employed to characterize the diversity, composition, and network structure of soil bacterial and fungal communities. According to the plant economic spectrum theory and our research results on plant root traits, HV can be identified as a resource-acquisitive cover crop, and RP treatment can be identified as a resource-conservative cover crop. Although RP treatment did not significantly increase the sweet potato yield, the increase rate reached 8.49%. Resource-conservative cover crops were associated with increased pH, SOC, and TP, which enhanced bacterial species diversity and boosted the populations of Chloroflexi and Alphaproteobacteria. In contrast, resource-acquisitive cover crops promoted the proliferation of Gammaproteobacteria. Network analysis indicated that resource-conservative cover crops facilitated network complexity through intensified intra-community competition. Resource-acquisitive cover crops enhanced the stability of microbial communities. Collectively, these findings underscore the distinct advantages of cover crops with varying root functional traits in shaping soil microbial communities. Appropriate cover crop rotations can effectively regulate microbial communities and hold the potential to enhance crop yield.