1a. Objectives (from AD-416):
Use the SWAT modeling framework to evaluate the transport of antimicrobials from swine manure applied to field-scale plots after simulated rainfall events. This project will address two components of antimicrobial transport: surface runoff and adsorption to soil in the upper unsaturated root zone.
1b. Approach (from AD-416):
The Soil and Water Assessment Tool currently does not model the transport and fate of emerging contaminants, such as antimicrobial compounds. Therefore, a numerical model will be developed from field experimental data to quantify the effect of rainfall and manure application method on antimicrobial transport from agricultural fields amended with swine manure. Data for model development were collected in summer 2011 and funded by the National Pork Board. Swine manure was obtained from the US Meat Animal Research Center (MARC) in Clay Center, Nebraska. Manure was applied at an agronomic N rate for corn. Application methods evaluated included a negative control (no manure applied), broadcast, broadcast with immediate incorporation and injection. Target antimicrobial compounds for evaluation include: chlortetracycline, tetracycline, carbodox, and bacitracin. Soil and surface run-off samples were collected in three sequential rainfall simulation experiments and analyzed for antimicrobial concentration, total and dissolved phosphorus, total nitrogen, NO3-N, NH4-N, chloride, pH, conductivity, antibiotic resistance genes (ARG), and total solids. This field data will be used to develop a plot-scale SWAT simulation to evaluate antimicrobial transport in this system.
3. Progress Report:
In a previous study, streams in the Shell Creek Watershed in Nebraska were monitored, and data on concentrations of pesticides and antimicrobials were collected. SWAT (Soil and Water Assessment Tool) input files were developed for Shell Creek, and data on pesticide and antimicrobial concentrations are being processed for comparison and validation of SWAT results.