Tuesday, November 14, 2006

Land Use Impacts on Soil Microbial Community Dynamics.

Heidi R. Kelly, Michael E. Konen, Melissa Lenczewski, and Lesley S. Rigg. Northern Illinois University, Department of Geography, 118 Davis Hall, DeKalb, IL 60115

Atrazine is a widely used pesticide that has been found to persist in the environment.  This study aims to examine the association between land use, landscape position, and soil microorganisms, particularly those capable of degrading atrazine, by comparing microbial community dynamics of a cultivated and adjacent non-cultivated catena in northeastern Illinois.  Sampling occurred across a spatial and temporal scale.  Soil characteristics including moisture content, temperature and CO2 respiration were measured weekly during the fall of 2005 and the spring and summer months of 2006 for the summit and footslope positions.  Microbial community characteristics were analyzed by plate counting on atrazine media and BIOLOG plating techniques while phospholipid fatty acid (PFLA) analysis was performed to determine microbial community structure composition.  The presence of atzA, atzB and atzC atrazine degradation genes was determined using PCR and quantified using real-time PCR.  Data was analyzed using principal component analysis (PCA) and tree regression.  Plate counts showed variation in microbial diversity and density between the cultivated and non-cultivated sites.  BIOLOG results indicated a higher diversity of carbon utilization in the non-cultivated samples while PFLA and PCR analyses also indicated variation in microbial community structure.  Investigating land use impacts on soil microorganisms will provide more insight into the effects on microbial community composition.