Distinct soil bacterial communities revealed under a diversely managed agroecosystem

Land-use change and management are normally enacted to manipulate environments to improve conditions that relate to production, remediation, and accommodation. However, soil microbial community complexity after manipulations is still difficult to quantify. In this study, replicate soil samples were collected from a demonstration farm in which three land-use systems were used (grazed pine forest, cultivated crop, and grazed pasture) on a single soil type in Perry County Alabama. Bacterial-tag encoded FLX amplicon pyrosequencing was used to generate genomic libraries targeting 16S rRNA. The different land use systems showed distinction in the structure of their bacterial communities with respect to the differences detected in cluster analysis as well as diversity indices. Specific taxa (particularly Actinobacteria, Acidobacteria, and classes of Proteobacteria) showed significant shifts across the land-use strata. Selected soil properties (soil organic matter [SOM], soil texture, pH, and phosphatase enzyme activity) also differed significantly across land-use systems, while SOM and pH showing variation consistent with shift in community structure and composition. Higher enzymatic activity (alkaline phosphatase, phosphodiesterase), SOM, and bacterial richness were observed in the grazed pasture. Together these results suggest that pyrosequencing along with traditional analysis of physiochemical soil properties may provide insight into the impact of land management practices on bacterial communities across heterogeneous landscapes.