Medicinal plant intercropping is a new intercropping method. However, as a new intercropping model, the influence of intercropping of alfalfa on microorganisms has not been clarified clearly. In this study, the composition and diversity of microbial communities in alfalfa intercropping were studied, and the differences of bacterial and fungal communities and their relationships with environmental factors are discussed. Intercropping significantly decreased soil pH and significantly increased soil total phosphorus (TP) content, but did not increase soil total carbon (TC) and total nitrogen (TN). Intercropping can increase the relative abundance of Actinobacteria and reduce the relative abundance of Proteobacteria in soil. The relative abundance and diversity of bacteria were significantly correlated with soil pH and TP, while the diversity of fungi was mainly correlated with TC, TN and soil ecological stoichiometry. The bacterial phylum was mainly related to pH and TP, while the fungal phylum was related to TC, TN, C: P and N: P. The present study revealed the stoichiometry of soil CNP and microbial community characteristics of mulberry-alfalfa intercropping soil, clarified the relationship between soil stoichiometry and microbial community composition and diversity, and provided a theoretical basis for the systematic management of mulberry-alfalfa intercropping in northwest Liaoning.

China is a country dominated by agriculture, but due to its geographical reasons, the western Liaoning region has caused sandstorms, and the desertified soil has reduced crop yields and suppressed the agricultural economy. Therefore, the concept of ecological agriculture and the agroforestry system received extensive attention. Arachis hypogaea are the main crop in the north of China. At present, the research on peanuts mainly focuses on grain crop intercropping, and there is limited research on the agroforestry of peanuts. In addition, Morus alba is a restorative plant emerging in China in recent years, which takes into account both ecological and economic benefits. Based on the above problems, we intercropped mulberry and peanut to explore their effects on farmland soil characteristics and rhizosphere soil bacterial and fungal communities. Our study showed that intercropping did not improve soil nutrients, but significantly reduced soil C:N, and reduced soil C:P and N:P to some extent. Intercropping improves the diversity and richness of soil microorganisms in farmland. The abundance of dominant bacterial and fungal phyla and genera increased in the soil. Actinobacteria were significantly negatively correlated with N:P, Proteobacteria was negatively correlated with TP and positively correlated with N:P., Ascomycota was positively correlated with soil nutrients and C:N, while Basidiomycota and Mortierellomycota were negatively correlated; Mycobacterium and RB41 were significantly correlated with phosphorus in soil, and Talaromyces were significantly positively correlated with soil nutrients and C:N. In conclusion, mulberry and peanut intercropping promoted soil humus, increased soil-available phosphorus content, and provided a good environment for microbial growth. These results provide new ideas for peanut agroforestry production and theoretical support for the construction of mulberry and peanut composite systems in Northeast China.