Submitted to: American Society for Microbiology
Publication Type: Abstract only
Publication Acceptance Date: 4/4/2011
Publication Date: 4/21/2011
Citation: Borchardt, M.A., Jokela, W.E., Spencer, S.K. 2011. Pathogen losses in surface runoff from dairy manure applied to corn fields. American Society for Microbiology. Abstract #1436. Interpretive Summary:
Technical Abstract: Background: Pathogens in manure applied to agricultural fields may be transported offsite via runoff and potentially transmitted to livestock and humans. This study is quantifying runoff losses of bovine enteric pathogens from dairy manure applied to corn silage fields under different manure/crop/tillage management systems. Methods: The paired-watershed research site in central Wisconsin consists of four 1.6 ha adjacent fields, each equipped with 60-cm H-flumes, flow meters, and automated runoff samplers. During runoff pathogens are concentrated continuously using glass wool filtration. Samples are analyzed for bovine enteric protozoa, bacteria, and viruses by qPCR and for indicator E. coli by fluorogenic assay. Data reported here are from one year of the calibration period (Nov 2007 – August 2008), during which all fields were treated identically with a single manure application (56,000 L/ha) in autumn immediately followed by chisel plowing. Results: The applied manure contained bovine enterovirus, rotavirus, Campylobacter jejuni, Salmonella enterica serovar Typhimurium, and Cryptosporidium parvum at concentrations ranging from 8.4 x 104 to 6.5 x 105 genomic copies/L. The first runoff occurred 6 months after application during snow melt in April; all pathogen types originally detected in the manure were present at concentrations ranging from 1 x 100 to 6.8 x 102 gc/L. Pathogen loss was greatest during snowmelt, however rotavirus, the pathogen applied at the highest concentration, continued to be detected in runoff into July. Of the 18 runoffs events through August, pathogens were measured in 10. Opposite to the seasonal levels of pathogens, indicator E. coli concentrations were highest in summer runoff and appeared correlated with daily soil temperatures. Conclusion: Pathogen genomes in dairy manure applied and tilled into fields in Wisconsin in autumn can be lost in runoff for many months following application. The time when exposure risk to pathogen-contaminated runoff is potentially greatest is not necessarily shown by measuring indicator E. coli.