Fungal communities are more sensitive to nitrogen fertilization than bacteria in different spatial structures of silage maize under short-term nitrogen fertilization

Soil microbial diversity plays key roles in plant nutrient acquisition and resilience. In recent years, interactions between plants and their associated microorganisms in soil have decreased due to the large-scale use of chemical fertilizers. Silage maize is one of the main silage feeds with high yield and rich nutrition. However, there is a lack of knowledge on how nitrogen application affects the soil (rhizosphere and bulk soil) and endosphere microbial communities of silage maize. In this study, the effects of nitrogen application rates on bacterial and fungal communities in the bulk soil, rhizosphere, and endophytic environment of silage maize were assessed. Our results showed that microbiome assembly along the soil-root continuum is shaped predominantly by spatial structures rather than by fertilization practice. From bulk soil to endophytic environment, the effects of nitrogen application on microbial communities decreased, and bacterial diversity and network coefficient consequently reduced. Moreover, nitrogen fertilization rates significantly affected fungal alpha diversity in bulk soil and endophytic environment, and nitrogen fertilization had greater impact on fungal community composition than bacterial in different sample types. The biomarkers of fungi sensitive to nitrogen treatment accounted for 25.5%, 11.4%, and 6.9% of all the taxonomic groups, respectively. The non-random collinearity analysis showed that Mortierellaceae, Sporormiaceae, and Geminibasidiaceae were the dominant fungal residing groups in bulk soil, rhizosphere, and endophytic environment, respectively. Therefore, the fungal community can be considered as an important indicator for silage maize in response to nitrogen application. In the N240 (240 kg N ha - 1) treatment, there was a more precise relationship between bacterial and fungal communities; however, this relationship weakened under higher nitrogen rates, and an increase in the nitrogen application rate weakened the interaction of the fungal community.