Integrating Cover Crops and Manure to Boost Goji Berry Yield: Responses of Soil Physicochemical Properties and Microbial Communities

A sustainable Goji berry (<i>Lycium barbarum</i> L.) planting system that integrates forage radish cover crops (<i>Raphanus sativus</i> L.) and animal manure has been established in northwestern China. This study investigated the effects of different cropping systems and manure application levels on soil physicochemical properties, microbial community structure, and <i>L. barbarum</i> yield under field conditions. A split-plot design was used, with the main-plot treatments consisting of two cropping systems and the sub-plot treatments involving three manure application levels. The results showed that compared to <i>L. barbarum</i> monocropping, cover cropping with <i>R. sativus</i> led to a decrease in soil bulk density (1.90%) and increase in soil electrical conductivity (11.5%), nutrient contents (total N and available N, P, and K: 30.3-138%), and microbial biomass (C: 79.0%; N: 184%). Cover cropping additionally enhanced the community diversity and richness of soil bacteria. Beta-diversity analysis revealed significant differences in bacterial rather than fungal community composition among various treatments. The bacterial network showed a lower ratio of positive to negative correlations and reduced complexity in response to cover cropping, which contrasted with fungal network patterns. Integration of cover cropping and medium manure application increased fruit yield by 8.71%. Cover crops and manure influenced soil microbial diversity mainly through their positive effects on soil total and available N contents.