Abstract
AbstractAlthough the land application of livestock manure has numerous agronomic benefits, runoff from manured fields can degrade water quality. Setbacks instruct a minimum distance be maintained between manure application and surface waters. They are commonly used to manage nutrient contamination of surface waters; however, their utility for reducing microbial inputs remains unclear. Here we evaluated the efficacy of five setback distances in no‐till wheat (Triticum aestivum L.) residue plots for reducing runoff fecal indicator concentrations from swine manure‐amended fields. Also, since there is increasing interest in the use of water quality indicators to monitor antibiotic resistance in environmental systems, Escherichia coli and Enterococcus isolates were collected, and evaluated for resistance to 12 antibiotics. Seven of the 12 antibiotics evaluated in this study are critically important to human health and another four of the antibiotics evaluated are highly important to human health, according to World Health Organization (WHO) guidelines. Significant differences existed in amounts of indicators from pre‐ and post‐manure application time points; however, no significant differences were observed for any of the five setback distances measured (range 4.9–23.2 m). Antibiotic‐resistant E. coli and Enterococcus were isolated from pre‐ and post‐application runoff, indicating presence of antibiotic‐resistant fecal indicators in both manured and in non‐manured soils, although the source manure had a higher percentage of isolates displaying resistance. It remains difficult to provide recommendations for concurrent reduction of nutrient and microbial contaminants.
Highlights
IntroductionSetbacks are rules or guidelines instructing a certain minimum distance be maintained between two points of interest
Significant differences were observed between setback distances for nutrient removal by Gilley et al (2016), who used the same setback distances and the same agronomic fields as this current study
One of the primary mechanisms identified for the removal of nutrients via setbacks or vegetative buffer strips is that the vegetation slows overland flow, allowing particulate matter and associated nutrients to settle before reaching surface waters (Dabney, Meyer, Harmon, Alonso, & Foster, 1995; Meyer, Dabney, & Harmon, 1995)
Summary
Setbacks are rules or guidelines instructing a certain minimum distance be maintained between two points of interest They are commonly used in agricultural settings as part of mandated nutrient management plans (Henry, 2003). Setbacks are required as part of the 1987 Water Quality Act (40 CFR 122.26) administered by the EPA National Pollutant Discharge Elimination System (NPDES) programs (USEPA, 2012a). They are used to limit contamination of surface waters from manure-borne nutrients. CAFOs may establish a 10.68 m wide (35 ft) permanent vegetated buffer strip, but this land may not be used for row crops. A third option for compliance is to demonstrate that an alternative practice provides reduction equivalent to the 30.48 m (100 ft) setback
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
