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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 4/19/2013 Publication Date: N/A Citation: N/A Interpretive Summary: Runoff from cattle feedlots is a mixture of rain and animal manure. It is nutrient rich, and can potentially be used to irrigate fields, but it also contains microorganisms that can make animals and people sick. We examined a system that collects the runoff, and uses it to irrigate perennial cool season grasses that are harvested for animal feed. We examined fecal indicator organisms, and two pathogens (E. coli O157:H7 and Salmonella) in feedlot runoff used for irrigation in a vegetative treatment system, and the persistence of these organisms in the fields over multiple years and at multiple soil depths. Fecal bacteria and pathogens numbers declined over time in the soil. The repeated application of manure-impacted irrigation water did not enrich the pathogens in the soil, and no evidence was seen to indicate that these bacteria were being vertically transported through the soil at this site. Results suggest that livestock-contaminated runoff can be effectively used for irrigation in this kind of system for the production of animal feed crops. Technical Abstract: Rainwater that is mixed with animal manures contains microorganisms that can adversely impact human and animal health, including fecal indicator microbes, pathogenic bacteria, and antibiotic resistant bacteria. Vegetative treatment areas have been proposed as a way to reduce nutrient and microbial concentrations and reduce the potential for environmental or human contamination. Through the use of vegetative treatment systems, cattle feedlot runoff was collected and used to irrigate perennial cool season grasses that were harvested for animal feed. We examined fecal indicator organisms, E. coli O157:H7 and Salmonella in feedlot runoff used for irrigation in a vegetative treatment system, and the persistence of these organisms in the fields over multiple years and at multiple soil depths. Soil depth profile samples of total coliforms, E coli, and Enterococcus from four replicate treatment areas showed distinct vertical profiles. Fecal bacteria and pathogens numbers declined over time in the soil. The repeated application of manure-impacted irrigation water did not enrich the pathogens in the soil, and no evidence was seen to indicate that these bacteria were being vertically transported through the soil at this site. The vegetative treatment system effectively reduces the concentrations of manure-associated bacteria in the soil over time in the treatment areas. |
