The effects of soil properties,cropping systems and geographic location on soil prokaryotic communities in four maize production regions across China

The diversity of prokaryotic communities in soil is shaped by both biotic and abiotic factors. However, little is known about the major factors shaping soil prokaryotic communities at a large scale in agroecosystems. To this end, we undertook a study to investigate the impact of maize production cropping systems, soil properties and geographic location (latitude and longitude) on soil prokaryotic communities using metagenomic techniques, across four distinct maize production regions in China. Across all study sites, the dominant prokaryotes in soil were Alphaproteobacteria, Gammaproteobacteria, Betaproteobacteria, Gemmatimonadetes, Acidobacteria, and Actinobacteria. Non-metric multidimensional scaling revealed that prokaryotic communities clustered into the respective maize cropping systems in which they resided. Redundancy analysis (RDA) showed that soil properties especially pH, geographic location and cropping system jointly determined the diversity of the prokaryotic communities. The functional genes of soil prokaryotes from these samples were chiefly influenced by latitude, soil pH and cropping system, as revealed by RDA analysis. The abundance of genes in some metabolic pathways, such as genes involved in microbe–microbe interactions, degradation of aromatic compounds, carbon fixation pathways in prokaryotes and microbial metabolism were markedly different across the four maize production regions. Our study indicated that the combination of soil pH, cropping system and geographic location significantly influenced the prokaryotic community and the functional genes of these microbes. This work contributes to a deeper understanding of the composition and function of the soil prokaryotic community across large-scale production systems such as maize.