Submitted to: Applied Engineering in Agriculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/18/2005
Publication Date: 7/1/2005
Citation: Woodbury, B.L., Nienaber, J.A., Eigenberg, R.A. 2005. Effectiveness of a passive feedlot runoff control system using a vegetative treatment area for nitrogen control. Applied Engineering in Agriculture 21(4):581-588. Interpretive Summary: Precipitation runoff from beef cattle feedlots is typically collected and stored in large volume ponds. These ponds are expensive to build, may leak after a few years, and pose a risk to groundwater quality. A runoff control system was designed and built that eliminated the need for storage ponds. The system had a temporary solid storage basin. Liquid was drained by gravity to a grass hay field where water and nutrients were utilized. No runoff was discharged from the grass hay field during the 3-year period, indicating all runoff was used by the crop. Total nitrogen removed by the hay crop equaled or exceeded the amount released from the settling basin. However, some areas in the grass hay field are accumulating nitrogen near the surface. Also, soil analysis in the basin indicates some nitrate is moving downward. These issues will continue to be addressed.
Technical Abstract: Producers are looking for cost-effective alternatives for controlling feedlot runoff. However, regulating agencies need to know these alternatives will protect the environment. As a result, a passive runoff control and treatment system was designed to provide solid separation and eliminate long-term liquid storage. This study was initiated to investigate the sustainability of a debris basin and vegetative filter strip (VFS) for nutrient control. The estimated total nitrogen load entering the VFS was equivalent to or less than the total nitrogen load removed by the crop. No water was measured exiting the VFS, either by deep percolation or by direct release, during the three-year study period. As a result, the discharge water from the basin was effectively used for hay crop production. Electromagnetic induction maps were produced to illustrate zones within the VFS where salt and nutrient loading occurred. Soil analyses in these zones indicated that surface soil nitrate-nitrogen levels, particularly closest to the discharge tubes, had increased. Currently nitrogen is contained near the surface, and has not started to infiltrate deeper into the VFS soil. However, nitrate-nitrogen appears to be infiltrating below the debris basin where concentrations as high as 60 mg NO3-N kg-1 soil were measured to a depth of three meters. Annual removal of the solids and organic material from the debris basin may have compromised sealing of the basin. Continued evaluation of the potential seepage is planned.