2013 Annual Report
1a.Objectives (from AD-416):
A field study will be conducted to evaluate the effectiveness of a vegetative treatment system (VTS) in removing nutrients, pathogens and fecal indicator microorganisms, and hormones in the runoff from a beef cattle feedlot in central Nebraska over a two-year period. Collaborations with University of Nebraska, Lincoln (UNL) engineers and scientists will be utilized to accomplish this research objective. Two sub-objectives have been developed to answer key questions about the effectiveness of the VTS system. These sub-objectives are:
1. Evaluate the removal efficiency of the VTS during standard operation.
2. Determine the vertical movement and persistence of nutrients and pathogens and fecal indicator organisms within the VTA.
1b.Approach (from AD-416):
Sub-objective #1, Normal VTS operation: …during 2010 and 2011… [add to the end]--Pooled samples of ‘clean’ rainwater runoff (two per event), feedlot runoff (four per event) and excess infiltration runoff (two per event) will be analyzed in the University of Nebraska Water Science Laboratory for hormones (nearly three dozen, including estradiols, testosterones, progesterones, estriols, and trenbolone) and antibiotics (tetracyclines/sulfonamides and macrolide/betalactams). These samples will also be screened for resistance the third generation antibiotic ceftiofur that is widely used in cattle (Excede, Naxcel) for problems such as foot rot or eye infections.
Sub-objective #2, Movement and persistence of nutrients and pathogens and fecal indicator organisms: Once each year, wastewater will be applied to four of the VTA treatment cells followed by collection of surface soil samples from five sites within each of the four cells and then sample those sites periodically over two weeks in order to understand how constituents in the wastewater are utilized, transformed, or removed. Soil depth profiles down to 30 cm (5 cm increments) will also be determined at those five sites in each of the four cells to help gauge the downward movement of microbes and nutrients. The 30-cm soil profile will be collected once each year to determine the movement of constituent over the two-year study.
An additional set of soil profile samples were collected from the VTS demonstration site near Rockford, NE in November. Analyses of antibiotic resistance in isolates were also completed. Statistical analysis of trends in nutrient, pathogen, antibiotic, and hormone data are being conducted.
Consistent with earlier initial analyses, the pattern of nutrients in the soil of the treatment cells shows trends for greater nutrient concentration at the surface compared to the deeper samples (50 cm). Phosphorus clearly shows this trend, and it is related to feedlot runoff inputs since the berm samples were generally uniform and lower in concentration. Sodium appears to show a general increase in treatment cells throughout the profile (compared to berm samples). Temporal trends in nutrient content indicate that some constituents (phosphorus) are accumulating very slowly over time. Transport and persistence of pathogens, hormones, and antimicrobial compounds in the soil are limited but dependent upon the compound. Monensin, which is high in applied wastewater, is remarkably low in surface soils and is likely broken down quickly.
From multiple environmental perspectives, the VTS is a good alternative to current systems handling runoff from cattle feedlot production systems.