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ARS Home » Plains Area » Lincoln, Nebraska » Agroecosystem Management Research » Research » Publications at this Location » Publication #338305
Title: Setback distance requirements for removal of swine slurry constituents in runoff

Author
item Gilley, John
item BARTELT-HUNT, SHANNON - University Of Nebraska
item ESKRIDGE, KENT - University Of Nebraska
item LI, XU - University Of Nebraska
item SCHMIDT, AMY - University Of Nebraska
item SNOW, DANIEL - University Of Nebraska

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2017
Publication Date: 12/1/2017
Citation: Gilley, J.E., Bartelt-Hunt, S.L., Eskridge, K.M., Li, X., Schmidt, A.M., Snow, D.D. 2017. Setback distance requirements for removal of swine slurry constituents in runoff. Transactions of the ASABE. Vol. 60(6):1885-1894.
DOI: https://doi.org/10.13031/trans.12310

Interpretive Summary: The establishment of vegetative filter strips at the bottom of a hillslope has been shown to significantly reduce pollutants in runoff. The use of setback distances on cropland areas where manure is not applied could serve a similar function. However, there is little information available to help identify setback distances required to effectively reduce contaminants in runoff. The objective of this study was to determine the effects of setback distance on concentrations of selected constituents in runoff following land application of swine slurry to a no-till cropland area. The study site consisted of 20 plots located on a benchmark soil in southeast Nebraska. An initial set of tests were completed using simulated rainfall to identify background concentrations of selected constituents. Swine slurry was then applied to an upper portion of each plot and additional field tests were conducted. The concentration of contaminants in runoff was found to rapidly decrease with increasing setback distance. A setback distance of 40 feet reduced the concentration of contaminants in runoff to background values similar to those measured on the no-slurry treatment. The transport of selected pollutants in runoff can be reduced significantly when appropriate setback distances are used.

Technical Abstract: The establishment of vegetative filter strips at the bottom of a hillslope has been shown to substantially reduce nutrients and sediment in runoff. The use of setback distances on cropland areas could serve a similar function. However, there is little information available to help identify setback distances required to effectively reduce the transport of contaminants in runoff. The objective of this study was to determine the effects of setback distance and runoff rate on concentrations of selected constituents in runoff following land application of swine slurry to a no-till cropland area. The study site had a residue cover of 7.73 Mg ha-1 and a slope gradient of 4.9%. The twenty plots examined during the investigation were 3.7 m across the slope by 4.9, 7.9, 11.0, 17.1 or 23.2 m long. An initial set of rainfall simulation tests were completed to identify background concentrations of selected constituents. Swine slurry was then applied to the upper 4.9 m of each plot and additional rainfall simulation tests were conducted. A first-order exponential decay function was used to estimate of the effects of setback distance on concentration values. A setback distance of 12.2 m reduced measurements of dissolved phosphorus, ammonium, total nitrogen, boron, chloride, manganese, potassium, sulfate, zinc, EC, and pH to background values similar to those measured on the no-slurry treatment. Runoff rate significantly influenced several of the constituents with concentration values generally decreasing as runoff rate increased. The transport of selected pollutants in runoff was significantly reduced when appropriate setback distances were used.