COPPER DISTRIBUTION ZINC DISTRIBUTION Soil P, Fe, Cu, and Zn levels were greatest in the open barn area. The run of retention area contained equally high levels of Fe and Zn as the open barn area. Soil P levels throughout the site exceeded the general environmentally safe level. Probably due to the nutrient recycling by forages grazing area contained much lower P, Fe, Cu, and Zn concentrations as compared to the open barn and run-off retention areas.. CONCLUSIONS Open barn area can serve as a significant source of P, Fe. Cu, and Zn contamination. Phosphorus contamination appeared to be a major threat from the beef cattle backgrounding. Elevated P, Fe, and Cu contents and the clay pane underlying the run-off retention area demands further study to examine the hydrologic connectivity between the run-off retention area with the nearby sink hole. REFERENCES Bradord, G.L.,J.A. Boling, S.R. Rutledge, and T.W. Moss, Comparing management Systems for beef cattle backgrounding: A multidisciplinary approach. Southern Journal of Agricultural Economics, Gerba, C.P., and J.E.Smith Sources of pathogenic microorganisms and their fate during land application of wastes. J Environ Qual 34: Jongbloed, A.W., and N.P.Lenis Environmental concerns about animal manure. J Anim Sci 76: Mehlich, A Mehlich 3 soil test extractant: A modification of Mehlich 2 extractant. Commun. Soil Sci. Plant Anal. 15: Meyer, M.T Use and environmental occurrence of veterinary pharmaceuticals in the United States. In. Pharmaceuticals in the environment: Sources, fate, effects, and risks. Ed. K.Kummerer. New York Springer-Verlag, EXPERIMENTAL SITE Western Kentucky University Agricultural Research and Education Complex, Bowling Green, KY. OPEN BARN AREA GRAZING AND RUN OFF RETENTION AREAS DIGITAL ELEVATION MODEL (DEM) AND THE SOIL SAMPLING LOCATIONS ABSTRACT Many beef cattle back grounding operations adopt either feedlot or combination of feedlot /grazing systems that create stocking situations similar to the concentrated animal feeding operational (CAFO). Under heavy rainfall events contaminants from these sites can move directly to the surrounding environments impairing soil and water quality. We examined the field scale soil nutrient variability in a beef cattle backgrounding site located within a close proximity to a sinkhole from open barn to run-off retention basin through a grazing area. Results indicated that the open barn area contained the highest soil test P, Fe, Cu, and Zn levels while the run off retention area also contained similarly high levels of Fe and Zn as the open barn area. The soil test P levels throughout the site exceeded the general environmentally safe level. The grazing area contained comparatively lower P, Fe, Cu, and Zn concentrations than the open barn and run-off retention areas. These findings suggest that open barn area of the site can be a significant source of P, Fe. Cu and Zn contamination. Phosphorus contamination appeared to be a major threat from the beef cattle backgrounding. Elevated nutrient levels and the underlying clay pane (as shown by the SSURGO soil masp) at the run-off retention area suggests further study to investigate the hydrologic connectivity between the run-off retention area with the nearby sink hole. INTRODUCTION The beef cattle backgrounding functions as the intermediate tier between the cow-calf enterprises and the feedlot finishing. Cattle backgrounding receives weaned calves of different growth stages from cow-calf operations and assembles them ready for feed lots as feeder calves. Many beef cattle backgrounding operations adopt either feedlot or combination of feedlot /grazing systems (Garnett et al. 1978) that keep steers/heifers confined to rather smaller areas creating stocking situations similar to the concentrated animal feeding operational (CAFO). CAFOs can contain contaminants like soil nutrients (Jongbloed and Lenis, 1998), microbial pathogens (Gerba and Smith, 2005), and veterinary pharmaceuticals (Meyer, 2004). Under heavy rainfall events, contaminants from these sites can enter the surrounding environments impairing soil and water quality. Beef cattle backgrounding on karst topography face extra problems because of karst geomorphic features like sink holes can funnel surface runoff from these sites rapidly into ground water. Understanding the spatial distribution of contaminants within beef cattle backgrounding sites becomes important to identify the critical source areas and to develop suitable best management practices (BMPs). MATERIALS AND METHODS As baseline information for a long term study that investigate the soil nutrient, microbial pathogen, and the veterinary pharmaceutical distribution and movement from beef cattle backgrounding sites on karst topography, we characterized the soil nutrient distribution within a beef cattle backgrounding site. This particular cattle backgrounding operation annually hosted six batches of fatteners (120 steers/heifers weighing 200 kg in each batch) for the past six years. We collected 66 geo referenced soil samples to a depth of 0-15cm, across the landscape from open barn area (n = 20) to runoff retention area (n=16) across a grazing land (n=30). We analyzed soil samples for Mehlich -3 (Mehlich, 1984) P, Fe, Cu, and Zn contents and measured the soil pH and the organic matter content. We interpolated point data for measured soil variable to the filed scale using geostatistical procedures. RESULTS SOIL ORGANIC MATTER DISTRIBUTION SOIL pH VARIABILITY TOTAL SOIL PHOSPHORUS DISTRIBUTION IRON DISTRIBUTION Field Scale Soil Nutrient Variability in a Beef Cattle Backgrounding Operation on Karst Topography Annesly Netthisinghe 1, Rebecca Gilfillen 1, Kimberley Cook 2, and Karamat Sistani 2. 1 Department of Agriculture, Western Kentucky University, 1906 College Heights Blvd. # 41066, Bowling Green, KY USDA-ARS Animal Waste Management Research Unit, 230 Bennett Lane, Bowling Green, KY SINK HOLE The authors wish to acknowledge the USDA-ARS for cooperation and funding of this research.