2007 Annual Report
1a.Objectives (from AD-416)
Our overall goals are 1. to understand better the survival kinetics and hydrologic transport characteristics of manure pathogens and their associated fecal indicator bacteria in agricultural watersheds, and 2. to improve our understanding of the emissions of ammonia and greenhouse gases from manures and manure applications. To accomplish goal 1., we propose three interrelated objectives: A) develop a method detection limit for Salmonella in environmental soil, poultry litter, and water samples with quantitative, real-time polymerase chain reaction (qPCR); B) determine inactivation or die off rates of Salmonella and the fecal indicator bacteria Escherichia coli and fecal Enterococcus spp. In field soils under controlled and field conditions; and C: determine the hydrologic transport characteristics of manure pathogens and fecal indicator bacteria at the field plot and small zero-order watershed scales. To accomplish goal 2., we propose to pursue the following two objectives: D) to measure ammonia and global-change trace gas emissions from land application of poultry litter under different tillage management, and E) from wetlands receiving nitrogen inputs from pastures.
1b.Approach (from AD-416)
Goal 1.: A real-time, quantitative polymerase chain reaction (qPCR) method will be developed to quantity the concentrations of Salmonella in poultry litter, and in environmental soil and water samples exposed to field applied poultry litter. With sentinel chambers, the aforementioned qPCR method, and defined cultural methods inactivation rates of Salmonella, and fecal indicator bacteria in agricultural soils will be determined under laboratory and field conditions. In collaboration with the Poultry Microbiological Safety Unit at the Russell Research Center, Athens,GA, and Southeast Watershed Research Laboratory, Tifton, GA overland transport of manure pathogens and fecal indicator bacteria from field applied poultry litter will be characterized at the field-plot level under various slope and aspect and under conditions of simulated rain, and at the small watershed-scale level that will depend on natural weather conditions. Goal 2.: Soil chambers will be used to measure gaseous emissions from poultry litter after soil application. Emissions will be evaluated under different tillage management systems. Small riparian/wetland areas will be studied to determine the proportion of hydrologic input nitrogen is transformed into gaseous nitrogenous emissions.
1) Practical Method for Enumerating Small Numbers of Salmonella in Surface Waters Developed. Watersheds with animal agriculture have the potential to adversely impact recreational waters and threaten public health by contaminating surface waters with fecal pathogens such as Salmonella. To understand better and manage the fate and transport of Salmonella in agricultural watersheds a most probable number (MPN) method for enumerating dilute densities of Salmonella in environmental waters was developed. This method has determined the density of Salmonella in 20 liter samples taken from the inflow and outflow streams of a pond in an agricultural watershed as low as 0.1 Salmonella cells/liter and identified substantial fluxes of Salmonella when the fecal indicator bacterium E. coli was not detected. The sensitivity of this method will enhance our understanding of the fate and transport of Salmonella in agricultural watersheds and because it has the potential for developing culture collections of this pathogen it may prove helpful in identifying the actual sources of this pathogen. This accomplishment contributes to the Manure and Byproduct Utilization National Program (206) Action Plan Area 3.C. Pathogens and Pharmaceutically Active Compounds (PACs) Component. Focus Area 1. Methods Assessment and Development. Focus Area 2. Fate and Transport of pathogens.
2) Intact Soil Column Experiments Demonstrated that the Sex Hormones Estradiol and Testosterone Can Move Through Worm Holes, Large Interconnected Pores, and Cracks in Soil to Contaminate Groundwater. The potent sex hormones estradiol and testosterone have been detected in surface waters throughout the developed world. Both hormones have been shown to adversely affect aquatic life, and have the potential of being a serious public health concern. The poultry industry generates millions of tons of poultry litter annually, much of which is applied to pastures and cropped fields as fertilizer, and both estradiol and testosterone are natural components of poultry litter. A study was initiated to determine if and how these hormones leach through soil to groundwater after a litter application. Intact soil columns were removed from an experimental field site and under laboratory conditions radioactively labeled estradiol and testosterone were applied to the surface of the soil columns in concentrations comparable to those contained in litter; several liters of water were applied and the water that leached out of the column was collected and analyzed for the hormones and the chloride tracer. Results of these soil column experiments indicated that these two sex hormones can move through worm holes, large interconnected pores, and cracks in the soil column, a phenomenon referred to as preferential flow and may contaminate groundwater. This is important information for the poultry industry and those responsible for developing manure management practices. This accomplishment contributes to the Manure and Byproduct Utilization National Program (206) Action Plan Area 3.C. Pathogens and Pharmaceutically Active Compounds (PACs) Component. Pathogens Focus Area 3. Pharmaceutically Active Compounds.
5.Significant Activities that Support Special Target Populations
|Number of non-peer reviewed presentations and proceedings||5|
|Number of newspaper articles and other presentations for non-science audiences||3|
Sangsupan, H.A., Radcliffe, D.E., Hartel, P.G., Jenkins, M., Vencill, W.K., Cabrera, M.L. 2006. Sorption and transport of 17b-estradiol and testosterone in undisturbed soil columns. Journal of Environmental Quality. 35:2261-2272.