Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/3/2012
Publication Date: 5/1/2012
Citation: Borchardt, M.A., Jokela, W.E., Spencer, S.K. 2012. Pathogen transport in surface runoff from manured agricultural fields. Meeting Abstract. September 23-26, 2012.
Technical Abstract: Research objective: Manure application to cultivated land is a sustainable approach for enhancing soil fertility and tilth. However, enteric pathogens are often common in manure and can be transported from the application site via runoff and potentially transmitted to livestock and humans. Our objectives are several: 1. Quantify a diverse group of bovine and zoonotic pathogens (protozoan, bacterial, viral) in surface runoff from field-scale sites, to which dairy manure is applied. 2. Relate pathogen occurrence and quantities to measurements of indicator E. coli, which is a common pathogen surrogate in runoff studies and water monitoring for public health. 3. Identify manure /crop/ tillage management practices that reduce pathogen transport from the application sites. Approach/innovation: A 6.4 hectare field located in central Wisconsin, USA, was divided by drive-through drainageways and berms into four 1.6 ha fields so that each has a single drainage point. The fields are comprised of Withee silt loam soil with 1-3% slope, and are cropped annually in corn harvested for silage. Manure (56,000 L/ha), obtained from the same herd every year, is applied once per year. Runoff stations are equipped with 60-cm H-flumes, flow meters, and automated samplers. During runoff pathogens are concentrated continuously using glass wool filtration. Samples are analyzed for enteric pathogenic protozoa, bacteria, and viruses by qPCR and for indicator E. coli by chromogenic assay. Treatment effects (i.e., different manure/cropping systems) on pathogen runoff are being evaluated by a paired-watershed design. Pathogen types and concentrations in the applied manure and subsequent runoff were highly variable by year. Runoff continued to contain pathogens many months after manure application. Indicator E. coli was not correlated with pathogen levels. In three years of runoff monitoring, total pathogen export ranged from 106 to 109 genomic copies/year, constituting 0.001% to 7% of the pathogen load applied to the land surface via manure. Importance: Unlike fecal indicator bacteria, data on pathogen quantities in agricultural field runoff are rare, particularly for manure related viruses. These data are valuable for identifying best management practices for reducing pathogen transport from agricultural sites and for assessing the health risk to livestock and humans from exposure to runoff and receiving waters.