Introducing intercropping into rotation system altered the structure, function and network complexity of soil microbial communities in farmlands of the North China Plain

Although diversified crop rotation systems can enhance crop productivity, the impact of such practices on soil microorganisms remains unclear. Therefore, we conducted a 4 - year field experiment in the North China Plain, involving 3 crop rotation systems: wheat - maize (WM), wheat - soybean (WS), and wheat - maize / soybean (‘/’ means intercropping, WMS), to analyze the structure, function and network complexity of soil microbial communities. The results indicated that compared to WM, the microbial abundance and diversity significantly increased in WMS, as evidenced by the rise in chao and shannon indices and the decrease in simpson index, which were not observed in WS. The microbial community structure also varied among different treatments, with significant increases observed in the total number of differential eutrophic bacteria in WMS and the total number of differential pathogenic fungi and archaea linked to Fe(II) oxidation and methane emission in WS. The abundance of microbial genes, encoding Glycoside hydrolases, Glycosyltransferases, Garbohydrate esterases, and Auxiliary activities, as well as those involved in Metabolism, Cellular processes and Genetic information processing, were clearly higher than those in WM or WS. Microbial co - occurrence network in WMS exhibited a greater number of nodes and edges, more positive edges, and higher average degrees and clustering coefficients when compared to WM or WS. For Hub nodes of these networks, they belonged to p_Proteobacteria in WM and WS, while in WMS they belonged to p_Actinobacteria. Organic carbon, alkaline hydrolysis nitrogen, and available phosphorus emerged as the predominant factors regulating the community composition of soil microorganisms. Consequently, we conclude the wheat - maize / soybean rotation system improves the abundance and diversity of soil microbial communities, strengthens microbial degradation and metabolism, and synthesis capabilities, thereby facilitating the establishment of favorable soil environment for crop growth.