The Quality of Grape Berries and Wine Is Enhanced Due to the Intercropping of Green Manure by Regulating Soil Microecology

Planting green manure between rows is an excellent green orchard cultivation practice. However, there is a lack of research on the application of such measures in vineyards. In this study, the ‘Beibinghong’ grape was used as experimental material, and clear tillage was used as a control. The effects of intercropping rape and pea between rows for two consecutive years on soil microecology and grape and wine quality were studied. The main results were as follows: intercropping green manure increased the berry pH. Intercropping green manure differentially modulated phenolic profiles in grape berries: pea intercropping significantly increased total phenolic and tannin contents relative to clean tillage across both years, whereas rapeseed intercropping showed variable effects depending on phenolic class and vintage. Green manure treatments also altered the accumulation of aldehydes, alcohols, and terpenoids. The intercropping of green manure could effectively reduce soil temperature and maintain soil moisture in the surface soil layer, reduce soil pH and electrical conductivity, and increase soil microbial biomass, aggregate amount, enzyme activity and soil fertility. Intercropping green manure changed soil microbial diversity and community structure. At the phylum level, the relative abundances of Chloroflexi (bacteria) and Mortierellomycota (fungi) were significantly increased. At the genus level, the genera Plectosphaerella and Alternaria—both dominant saprotrophic fungi—were also significantly enriched. The results of a comprehensive evaluation of principal component and membership function and sensory evaluation showed that intercropping peas was the best strategy. Soil pH, electrical conductivity, nitrate content, LAP activity, and the phyla Acidobacteriota, Chloroflexi, and Mortierellomycota were significantly correlated with the acid content of wine, while soil enzyme activity was significantly correlated with the phenolic content of wine. These results indicated that intercropping green manure could drive the quality of grapefruits and wine by regulating soil nutrients, enzyme activities, basic physical and chemical properties, and microbial communities.