Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: March 15, 2003
Publication Date: October 12, 2003
Citation: WOODBURY, B.L., NIENABER, J.A., EIGENBERG, R.A. NITROGEN MANAGEMENT OF A FEEDLOT RUNOFF CONTROL SYSTEM WITH VEGETATIVE FILTER STRIP. AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS MEETINGS PAPERS. Proc. 9th Int'l. Symp.ISAAFPW 2003.pg. 372-380. Interpretive Summary: Precipitation runoff from beef cattle feedlots is typically collected in large storage ponds. These ponds are relatively expensive to build and seepage may occur. A runoff control system was designed and constructed to eliminate the need for traditional storage ponds. This system features a temporary storage basin for removing solids contained in the runoff. The liquid portion is drained to a grassed field where the water and nutrients are used to produce a hay crop. This report is a summary of the system performance. Up to 80% of the solids in the runoff were collected in the basin. No runoff water was measured leaving the hay field, indicating it was used to produce a hay crop. A greater amount of nutrients was removed by the hay than was discharged to the field in the runoff. This would indicate the runoff control system is appropriately sized and adequately protects the environment. Soil tests indicate a build-up of nutrients near the outlet of the basin discharge. However, this build-up is located only on the surface but could move deeper into the soil with time. Continued maintenance of the system should sustain treatment performance and protect the environment.
Technical Abstract: Runoff from beef cattle feedlots is usually stored in holding ponds. These ponds can be a concentrated source for contaminating surface and groundwater. Vegetative filter strips (VFS) can be effective in protecting surface and groundwater by reducing diffuse contamination. The objectives of this project were to evaluate the contaminant control by the system, and to determine the sustainability of the VFS for nutrient and runoff water control. A runoff control system for a small feedlot was constructed to utilize a VFS for water and nutrient control. To reduce contamination load, a debris basin was constructed to collect and store suspended solids. The basin provided 5 - 8 minute hydraulic retention, before evenly discharging the water across the VFS. Over a three year period, the debris basin effectively reduced the mass of total and volatile suspended solids, and chemical oxygen demand by 80, 67, and 59%, respectively. Significant contaminant reductions in the runoff water were measured as it passed through the system for most precipitation events. No water was measured exiting the VFS during the three year study period by either infiltration below the root zone or by direct release from the site; therefore, the discharge water from the basin was effectively used for hay crop production. The estimated total nitrogen load in the discharge water entering the VFS was equivalent to or less than the total nitrogen removed by the crop. Two-dimensional electromagnetic induction maps have been generated beginning before the VFS was put in operation and have continued to the present. These maps were used to illustrate zones within the VFS where salt and nutrient loading are occurring. The apparent electrical conductivity of the VFS in the region of the debris basin discharge tubes have been disproportional increased due to salt and nutrient loading. Surface soil nitrate-nitrogen levels, particularly closest to the discharge tubes, have also increased.