SOIL ORGANIC MATTER AND NUTRIENT CYCLING TO SUSTAIN AGRICULTURE IN THE SOUTHEASTERN USA
Location: Athens, Georgia
Title: Inorganic fertilizer and poultry-litter manure amendments alter the soil microbial communities in agricultural systems
Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2008
Publication Date: June 5, 2008
Citation: Kamlesh, J., Williams, M.A., Franzluebbers, A.J., Sanderlin, J.S., Reeves, J.H., Jenkins, M., Endale, D.M., Coleman, D.C., Whitman, W.B. 2008. Inorganic fertilizer and poultry-litter manure amendments alter the soil microbial communities in agricultural systems [abstract]. Annual Meeting of the American Society for Microbiology Annual, June 1-5, 2008, Boston, Massachusetts. CD-ROM.
The effects of agricultural land management practices on soil prokaryotic diversity are not well described. We investigated three land usage systems (row cropped, ungrazed pasture, and cattle-grazed pasture) and two fertilizer systems (inorganic fertilizer or IF and poultry-litter or PL) and compared them to a >50 year old forest at the J. Phil Campbell, Sr., Natural Resource Conservation Center, Watkinsville, Georgia. Community DNA was extracted from soil in winter and summer, and the prokaryotic and microbial community composition and diversity were assessed using 16S rRNA gene clone libraries and phospholipid fatty acid (PLFA) analyses. LIBSHUFF analysis of the libraries indicated that the bacterial communities from soils under all seven treatments were significantly different. However, those from the forest were clearly distinct from the others. Hierarchical linear modeling of taxa abundance within the agricultural soils revealed that the effect of fertilizer was more dramatic than land use or season. Of the 14 taxonomic groups tested, PL amendments influenced the abundance of 7, whereas land use and season influenced the abundance of only 5 and 3, respectively. Specific associations between certain operational taxonomic units and soil types were also noted. The multivariate nonmetric multidimensional scaling of the mol % PLFA indicated that the forest communities were very different from the agricultural soils. While fungi were relatively more abundant in the forest, bacteria dominated the agricultural soils. In addition, the bacterial communities in the IF-amended cropped soils were different from the pasture and PL-amended cropped soils. The PL amendments also had a large affect on community structure. In contrast, the effects of season were generally small. The PLFA analysis reflected many of the same trends detected in the 16S rRNA gene analysis, however some of these differences may be a result of physiological responses to changing soil environments rather than a reflection of the community structure per se. The community-level differences were related to differences in soil chemical properties. Agricultural land management practices influenced the composition of soil microbial communities, most likely from their effects on the quality and quantity of organic resource inputs and differences in microclimate among systems that affected microbial activity with time.