|Thurston Enriquez, Jeanette|
Submitted to: Journal of Water and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2004
Publication Date: January 1, 2005
Citation: Thurston Enriquez, J.A., Gilley, J.E., Eghball, B. 2005. Microbial quality of runoff following land application of cattle manure and swine slurry. Journal of Water and Health 3(2):157-171. Interpretive Summary: Waterborne outbreaks of disease have been associated with precipitation events that carry microorganisms to water bodies serving as recreational and drinking water sources. In order to determine the load of health related microorganisms from manure-applied land, rainfall simulation events were conducted and runoff was collected from experimental plots treated with swine manure, cattle manure, or inorganic fertilizer. The health-related microorganisms assessed in this study included those used to evaluate the microbial quality of surface water. Relatively high concentrations of these microorganisms were observed in runoff from plots containing manure compared to those treated with inorganic fertilizer. These results suggest that heavy precipitation events may release large numbers of health-related microorganisms from manure treated land and impact water bodies within the watershed.
Technical Abstract: Concentrations of human health-related microorganisms in runoff from agricultural plots (0.75 x 2 m) treated with fresh and aged cattle manure, swine slurry, and no manure (control) were determined. Three consecutive simulated rainfall events, producing 35 mm rainfall each and separated by 24 hr, were carried out for each plot. Fecal indicator (Escherichia coli, enterococci, Clostridium perfringens, and coliphage) loads released in rainfall runoff from plots treated with fresh cattle manure, aged cattle manure, and swine slurry treatments ranged from 5.52 x 105 to 4.36 x 109, 3.92 x 104 to 4.86 x 108, and 9.63 x 105 to 3.05 x 108, respectively. Plot runoff concentrations of protozoa (Cryptosporidium oocysts and Giardia cysts) ranged from 1.65 x 105 to 1.04 x 106, 2.93 x 103 to 2.75 x 105, and 9.12 x 104 to 3.58 x 106 for fresh cattle manure, aged cattle manure, and swine slurry plot treatments, respectively. These results suggest that large microbial loads could be released via heavy precipitation events that produce runoff from livestock manure-applied agricultural fields, of even modest size, and could significantly impact water bodies within the watershed. Because of the lack of multiplication in the environment, highly elevated concentrations in manured land runoff, and correlation to protozoan parasite presence, Clostridium may be an alternative indicator for livestock manure contamination.