Transport of Fecal Pollution Indicators: Impacts from the Land Spreading of Liquid Manure on Water Quality

This thesis is a case study to determine if groundwater and/or drainage tiles are important pathways for fecal migration to streams resulting from the application of liquid manure to cropland at a small dairy farm, the Little River Animal and Environmental Unit, near Townsend, TN. Traditional biological indicators, coliforms and E.coli, were used in conjunction with a bovine specific Bacteroides assay to measure fecal microbes. Total nitrates, turbidity, and other chemical parameters for water quality also were used to identify related fecal contamination. This thesis covers three separate manure applications. The first manure application occurred in May 2013, the second in November 2013, and the third in May 2014. Water samples were collected from shallow groundwater wells, a drainage ditch, drainage tiles, and the river adjacent to the dairy

The first liquid manure application resulted in significant changes in E.coli, AllBac, and nitrates. During the first manure application E.coli concentrations in the drainage tiles, drainage ditch, and Little River had statistically significant increases compared to samples collected before the application. AllBac only significantly increased in the Little River, and cannot be definitely ascribed to the liquid manure application because of possible upstream inputs. However, the sudden presence of detectable levels of BoBac in the surface drainage ditch, wells, and Little River after the application provides a strong line of evidence that fecal pollution was transported around the study site.

In contrast to the first manure application, no significant changes were observed for any of the fecal markers in subsequent applications. During the second application, November 4^th through 7^th of 2013, and third manure application, May 21^st through 24^th of 2014, there was no precipitation in the weeks before and after the applications, and the depth to the water table was greater than the first application.

These results suggest it is possible to apply large volumes of liquid manure and have minimal/non-detectable impacts on surface and ground water quality. However, this is only true when the liquid manure occurs during optimum hydrologic conditions and best management practices are in place to prevent direct application of liquid manure to surface waters.