Location: Agroecosystems Management ResearchTitle: Effects of tillage and poultry manure application rates on Salmonella and fecal indicator bacteria concentrations in tiles draining Des Moines Lobe soils Author
|Hruby, Claire - Iowa State University|
|Soupir, Michelle - Iowa State University|
|Moorman, Thomas - Tom|
|Shelley, Mack - Iowa State University|
|Kanwar, Ramesh - Iowa State University|
Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2016
Publication Date: 1/30/2016
Citation: Hruby, C.E., Soupir, M.L., Moorman, T.B., Shelley, M., Kanwar, R.S. 2016. Effects of tillage and poultry manure application rates on Salmonella and fecal indicator bacteria concentrations in tiles draining Des Moines Lobe soils. Journal of Environmental Management. 171:60-69.
Interpretive Summary: Application of poultry manure (PM) to cropland as fertilizer is a common practice in the Upper Midwest. Much of the land in this region has subsurface drainage which could potentially transport pathogenic bacteria from poultry manure to downstream waters. In this 3-year study (2010-2012), poultry manure was applied annually in spring, prior to planting corn at rates needed for corn production. Control plots received no manure. Manure and drainage water samples were analyzed for Salmonella, E. coli, and Enterococcus. All three bacteria were detected in drainage waters, with the high Salmonella concentrations in some samples. Concentrations of Enterococcus were more strongly correlated to Salmonella than for E coli, suggesting that Enterococcus might be a better indicator of contamination. The study demonstrates that subsurface drainage can transport pathogenic bacteria present in poultry manure. This information is of interest to scientists, poultry producers and water quality specialists in state government.
Technical Abstract: Application of poultry manure (PM) to cropland as fertilizer is a common practice in artificially drained regions of the Upper Midwest. To assess the potential for PM to contribute pathogenic bacteria to downstream waters, information is needed on the impacts of manure management and tillage practices on bacteria transport to drainage tiles under a wide range of field conditions. In this 3-year study (2010-2012), PM was applied annually in spring, prior to planting corn. PM application rates ranged from 5 – 40 kg/ha to achieve target rates of 112 and 224 kg/ha nitrogen (PM1 and PM2). Control plots received no manure (PM0). Each treatment was replicated on three chisel-plowed (CP) plots and one no-till (NT) plot. Water samples were collected weekly from drainage tile outlets and following precipitation events from 30 days before manure application to 100 days post application, when tiles were flowing. In 2011 and 2012, additional tile monitoring was employed to capture the hydrographic response to precipitation, and in 2012, smoke-testing was used to determine macropore densities. Manure and tile-water samples were analyzed for the pathogen, Salmonella spp. (SALM), fecal indicator bacteria (FIB), E. coli (EC), and enterococci (ENT). All three bacterial species were detected in tile-waters, with the highest plot-normalized concentrations observed under the NT PM2 plot in 2010 (3.7 × 104 cfu/100 mL EC, 3.6 × 106 cfu/100 mL ENT, and 1.6 × 104 cfu/100 mL SALM). Individual and 30-day geometric mean ENT concentrations correlated more strongly to SALM than EC.