Abstract: We assessed the effects of cover crops on soil physicochemical properties and microbial community structure composition and function in winemaking vineyards (‘Chardonnay’ grapes) in the eastern foothills of Helan Mountains. There were three cover cropping modes, namely, clear tillage, natural grassing, and planting Vicia villosa. Soil microbial community characteristics were analyzed by high-throughput sequencing technology. The results showed that compared with clear tillage, soil organic matter, total nitrogen, available nitrogen and total phosphorous contents were significantly increased in the grassing treatments. The best effect was found in Vicia villosa treatment, with the contents of soil organic matter, total nitrogen, available nitrogen and total phosphorous being 8.76 g·kg^-1, 1.16 g·kg^-1, 26.13 mg·kg^-1 and 0.58 g·kg^-1, respectively. The grassing treatments increased the   activities of soil peroxidase, cellulase, and amylase. In contrast to clean tillage, the grassing treatments significantly increased the Shannon and Chao1 indices of soil bacterial community, whereas no significant differences were observed for the fungal community. The results of microbial community composition analysis showed that Proteobacteria (25.78%-30.46%), Actinobacteriota (14.12%-16.15%), and Bacteroidota (9.37%-15.91%) were the dominant bacterial phyla, and Ascomycota (68.77%-88.20%) was the dominant fungal phylum. Intergroup community difference analysis (LEfSe) showed that the three groups of soil samples obtained a total of 65 significantly different bacterial taxa and 38 significantly different fungal taxa. Tax4Fun functional prediction obtained a total of six first-level functional layers, which showed the high functional richness of bacteria, and the soil bacterial community was functionally active in metabolism, genetic information processing, and environmental information processing. FunGuild analysis showed that planting Vicia villosa facilitated the colonization of soil saprotroph, pathotroph-saprotroph and pathotroph-saprotroph-symbiotroph fungi. In conclusion, cover crops enhance soil fertility and enzyme activities, and optimize the structure and function of microbial communities, which is conducive to the improvement of soil ecological environment in vineyards.

Key words: eastern foothills of Helan Mountain, vineyard, cover cropping, soil microorganisms, functional prediction