Soil chemical properties drive the structure of bacterial communities in the cotton soil of arid Northwest China

Abstract

Over the last few decades, much of the desert-oasis ecotone in northwestern China has been reclaimed for cotton cultivation. However, we still know little about the composition of the soil bacterial community relative to soil chemical properties in reclaimed soil after long-term monocultural cotton production in arid and extremely arid areas. Here, we collected soil samples from two farms where cotton has been continuously planted for more than 20 years. We found that the composition of the soil bacterial communities was significantly different between these two farms, variance in which could be explained by available K, N, and P, total N, and soil pH. The relative abundance of Verrucomicrobia was significantly higher at the Xinhu farm, while Bacteroidetes and Nitrospirae predominated at the Tenth farm. Across sites, the abundance of Bacteroidetes was positively correlated with available N and P, while the abundance of Verrucomicrobia was positively correlated with total N and available K. Moreover, bacterial community diversity, as quantified via phylogenetic diversity, Shannon diversity, and operational taxonomic unit richness, was higher at the Tenth farm. These soil bacterial diversities were all positively correlated with available N, but negatively correlated with available K in arid and extremely arid areas. Our results suggest that available K, N, and P, total N, and pH are all key factors in shaping soil bacterial communities. The influence of available N and K on bacterial community diversity should therefore be considered for cotton cultivation in reclaimed soil.