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Evaluating the Effectiveness of Best Management Practices (BMPs): Controlling Pathogenic Bacteria from CAFOs
Pathogenic microorganisms of fecal origin are one of the leading causes of impairment of rivers and streams in the United States, and pose significant risk to human health. Nonpoint source pollution from agricultural operations, particularly spreading animal manure on cropland, may be a source of pathogens in these impaired waters. The use of antibiotics as promoters of growth or for treatment of animal disease may exacerbate health risks by creating antibiotic-resistant strains, which may inhibit treatment for exposed individuals.
Vegetative buffer strips are non-basin management practices that have found wide application for the control of sediment and nutrient runoff in agricultural areas. However, the ability of this technology to control pathogens from confined animal feedlot effluents and manure-treated croplands is poorly understood. This study evaluates vegetative buffer strips for reducing pathogen discharge to streams adjacent to, or running through, manure-treated croplands and animal feedlot effluent application areas. Of particular interest are the application rates necessary to achieve discharge objectives based on ambient water quality criteria in impacted watersheds, or maximum loading rates, which are critical when establishing basic pre-application treatment objectives.
Current microbial indicators of fecal contamination, such as E. coli, enterococci, and Bacteroides, will be used to quantify vegetative buffer strip effectiveness through a mass balance approach. E. coli and enterococci harboring specific genetic virulence traits or exhibiting antibiotic resistance will be used as markers for bacterial pathogenicity. Completion of the project objectives relies on the use of quantitative molecular microbiological techniques to monitor selected fecal bacteria and genetic virulence indicators. Complicating factors that will be addressed in this study include the potential for bypassing the treatment area through drainage tiles and the storage and subsequent release of pathogens in stream sediments during rainfall events. As vegetative buffer strips may be the only management practices widely used to control agricultural runoff, a better understanding of their effectiveness for pathogen removal is imperative before establishing total maximum daily loads (TMDLs) for manure application, and improving water quality in agricultural areas. The results of this study are expected to complement current research into the reduction of environmental risk from synthetic and natural hormones, pharmaceuticals, and nutrients originating from concentrated animal feeding operations, and lead to better manure management practices.
Contact: Shane Rogers (EIMS#116064)