Core Microbiota in Agricultural Soils and Their Potential Associations with Nutrient Cycling

Revealing the ecological roles of the core microbiota in community maintaining and soil nutrient cycling is crucial for understanding ecosystem function, yet there is a dearth of continental-scale studies on this fundamental topic in microbial ecology. Here, we collected 251 soil samples from adjacent pairs of maize and rice fields at a continental scale in eastern China. We revealed the major ecological roles of the core microbiota in maintaining complex connections between bacterial taxa and their associations with belowground multinutrient cycling. By identifying the habitat preferences of the core microbiota, we built a continental atlas for mapping the spatial distributions of bacteria in agro-soils, which helps forecast the responses of agricultural ecosystems to anthropogenic disturbance. The multinutrient cycling index for maize and rice soils was related to bacterial α-diversity and β-diversity, respectively. Rice soils exhibited higher bacterial diversity and closer bacterial cooccurrence relationships than maize soils. In contrast to the macro- or microecological latitudinal richness patterns in natural terrestrial ecosystems, the bacteria in maize soils showed higher richness at high latitudes; however, this trend was not observed in rice soils. This study provides a new perspective on the distinct bacterial biogeographic patterns to predict the ecological roles of the core microbiota in agro-soils and thus helps manage soil bacterial communities for better provisioning of key ecosystem services. IMPORTANCE Disentangling the roles of the core microbiota in community maintaining and soil nutrient cycling is an important yet poorly understood topic in microbial ecology. This study presents an exploratory effort to gain predictive understanding of the spatial atlas and ecological roles of the core microbiota. A systematic, continental-scale survey was conducted using agro-soils in adjacent pairs of maize (dryland) and rice (wetland) fields across eastern China. The results indicate that the core microbiota play major ecological roles in maintaining complex connections between bacterial taxa and are associated with belowground multinutrient cycling. A continental atlas was built for mapping the bacterial spatial distributions in agro-soils through identifying their habitat preferences. This study represents a significant advance in forecasting the responses of agricultural ecosystems to anthropogenic disturbance and thus helps manage soil bacterial communities for better provisioning of key ecosystem services-the ultimate goal of microbial ecology.