Monday, November 13, 2006 - 2:00 PM
90-3

Differences in Release and Transport of Manure-Borne E. Coli and Enterococci in Grass Buffer Conditions.

Y.A. Pachepsky1, Andrey Guber2, Jeffrey Karns1, Ali M. Sadeghi3, Jo Ann S. van Kessel1, and Thanh H. Dao4. (1) USDA-ARS-BA-ANRI-EMSL, Bldg. 173, Rm. 203, BARC-EAST, Powder Mill Road, Beltsville, MD 20705, (2) Dept. of Environmental Sci, University of California, Riverside, A135 Bourns Hall, Riverside, CA 92521, (3) USDA-ARS-BA-ANRI-HRSL, Bldg. 007 Rm 104 BARC-WEST, Baltimore Ave 10300, Beltsville, MD 20705, (4) USDA-ARS-BA-ANRI-AMBUL, 306 Powder Mill Rd, BARC-East, Beltsville, MD 20705

Escherichia coli and enterococci are common indicator organisms used to detect potential fecal contamination of surface and ground water and to determine water quality. Coupled monitoring of both organisms in the karst environment demonstrated differences in dynamics of their concentrations in waters that were reached by fecal contamination. Little is known about the differences in transport of the two indicator organisms in soil, or about the differences in their overland transport. The objective of this work was to test the hypothesis that the two organisms have similar patterns of release from animal feces and subsequent transport in the environment. The turfgrass soil sod was placed into boxes that were 10 cm deep, 40 cm wide and 200 cm long, and had top 25-cm section separated to monitor the release and infiltration of bacteria that occurred in the rest of the box. Boxes with either live or dead grass were placed under rainfall simulator and tilted to have 4 % slopes. Dairy manure was broadcast on the upper 50-cm section. Rainfall was simulated for 90 min and runoff samples were collected and analyzed for Br, E. coli, enterococci and turbidity. Significant differences in release kinetics of E. coli and enterococci were found. Differences in the subsequent transport could not be observed for E. coli and enterococci. The change from the first order release kinetics to the zero order release kinetics after 1 h of rainfall was observed. Because both E. coli and enterococci are currently used as indicator organisms for manure-borne pathogens, differences in their release rates may affect the efficiency of using these organisms as indicators of fecal contamination from lands in agricultural use.