Soil Bacterial Community Composition and Diversity as Affected by Animal Manure Application in Pasture and Cropping Systems of the Southern Piedmont USA.
Kamlesh Jangid1, Mark A. Williams2, Alan Franzluebbers3, Michael Jenkins3, David C. Coleman1, and William B. Whitman1. (1) Univ of Georgia, Dept of Microbiology, Athens, GA 30606, (2) Mississippi State Univ, Mail Stop 9555, Dorman Hall, MS State, MS 39762, (3) USDA-ARS, 1420 Experiment Station Rd., Watkinsville, GA 30677
Soil is one of the largest reservoirs of prokaryotes in the biosphere, and may contain approximately 2.6 x 1029 cells worldwide or 5% of all the prokaryotic cells on earth. The prokaryotic diversity in soil is also enormous, with some theoretical estimates suggesting that typical soil communities contain 3,000-8,000 species. While land management practices are known to have a tremendous impact on agro-ecosystems and their microbial activities, its effects on prokaryotic diversity are not well described. We used molecular methods to examine the bacterial communities in pasture and cropped soil with and without animal manure application. Mixed community DNA was extracted from soil and the bacterial 16S rRNA genes were amplified in low cycle number PCR, cloned, and sequenced. The composition and diversity of the community were analyzed by RDPquery, LIBSHUFF, and other methods. Seven management systems were investigated on Typic Kanhapludults at the J. Phil Campbell, Sr., Natural Resource Center near Watkinsville, Georgia: (1) control forest without agriculture since the Civil War, (2) cropping with inorganic fertilizer, (3) cropping with poultry litter fertilizer, (4) bermudagrass hay with inorganic fertilizer, (5) bermudagrass hay with poultry litter fertilizer, (6) bermudagrass grazed by cattle receiving inorganic fertilizer, and (7) bermudagrass grazed by cattle receiving poultry litter fertilizer. This treatment arrangement allowed us to discern the effects on soil biological diversity from (i) land use with and without manure inputs, (ii) poultry manure applied to crop and pasture lands, and (iii) the combined effects of cattle and poultry manure in pasture land.