Shaping the succession patterns of different soil nutrients, enzyme stoichiometry, and microbial communities through rotation systems

The ecological environment and function of farmland soil are strongly affected by crops. However, there is still a lack of understanding of how the soil microbial environment responds to crop changes in rotation systems. Therefore, we studied wheat-maize (W-M) and garlic-maize (G-M) crop rotation systems to explore the re-sponses in terms of soil nutrients and the microbial community to different tillage systems. The results showed that the W-M cropping system was continuously limited by phosphorus nutrition, and the G-M cropping system was alternately affected by nitrogen and phosphorus nutrition due to the different nutrient requirements of crops. The bacterial communities were significantly affected by the cropping systems and crop types, whereas the fungal communities were only affected by the crop types. Compared with W-M, G-M increased the abundances of Nitrospirae, Bacteroidetes, and Rokubacteria in the bacterial community, and decreased the abundance of Basidiomycota in the fungal community, as well as increasing the nodes and links between bacterial communities but weakening the links between fungal communities. Compared with W-M, G-M decreases the contents of soil organic carbon and total nitrogen, increases the diversity and abundance of bacteria, and decreases the diversity of fungi, thereby reducing extracellular enzyme C/N and N/P, and increasing the activity ratio of C/P, ultimately reduces C and P limitations and increases N limitations. Differences in crop types result in greater changes in soil bacteria than fungi in crop rotation systems. Our study provides more insights into the relationship between soil nutrient limitation and microenvironment in rotation systems.