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Evaluation of Best Management Practices for Controling the Release of Pathogenic Bacteria Originating from Concentrated Animal Feed Operations
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. Non-point-source pollution from agricultural operations, particularly spreading animal manure on cropland, may be a major source of pathogens in these impaired waters. The use of antibiotics as growth promoters or for treatment of animal disease may exacerbate health risks by creating antibiotic resistant strains that may resist treatment in 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 efficacy of this technology for controlling pathogens from confined animal feedlot effluents and manure-treated croplands is poorly understood. This study aims to evaluate 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 is to obtain a better understanding of appropriate application rates to achieve discharge objectives based on ambient water quality criteria in affected watersheds. These maximum loading rates are critical to 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 and/or exhibiting antibiotic resistance will be used as markers for bacterial pathogenicity. Completion of the project objectives will rely 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 in use to control agricultural runoff, a better understanding of their effectiveness for pathogen removal is imperative to 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 ongoing research concerning the reduction of environmental risk from synthetic and natural hormones, pharmaceuticals, and nutrients originating from confined animal feed operations, and lead to better manure management practices.
Contact: Shane W. Rogers, 513/569-7104, (EIMS#116064)