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Title: Distinct soil bacterial communities revealed under a diversely managed agroecosystem

Author
item SHANGE, RAYMON - Tuskegee University
item ANKUMAH, RAMBLE - Tuskegee University
item Ibekwe, Abasiofiok - Mark
item ZABAWA, ROBERT - Tuskegee University
item DOWD, SCOT - Molecular Research Lp (MR DNA)

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2012
Publication Date: 7/23/2012
Citation: Shange, R.S., Ankumah, R.O., Ibekwe, A.M., Zabawa, R., Dowd, S.E. 2012. Distinct soil bacterial communities revealed under a diversely managed agroecosystem. PLoS One. 7(7):e40338. doi:10.1371/journal.pone.0040338.

Interpretive Summary: Land use change and management are highly consequential actions of humans on the environment, as humans convert forested, pastured, and other natural ecosystems to meet agricultural, urban, or other needs. These disturbances have measurable impacts to their respective ecosystems in the forms of soil cycling of organic compounds, biodiversity, and soil nutrient dynamics. The sensitivity of microbial communities to changes in management as well as their importance to nutrient cycling attests to their use as early indicators of change in the quality of the soil ecosystem. In this study soil samples were collected from a farm with three land use systems, different bacterial populations were determined, and different bacterial groups were dominant in different land use systems. Soil organic matter and pH were the dominant factors controlling changes in bacterial populations. Therefore, any soil management strategy that will result in a major shift in soil pH and organic matter must be avoided so as to maintain good soil quality for sustainable agricultural practices. This research will directly benefit farmers, conservation biologists, and the public.

Technical Abstract: 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.