Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: 5/9/2008
Publication Date: 7/7/2008
Publication URL: asae.frymulti.com/
Citation: Woodbury, B.L., Eigenberg, R.A., Nienaber, J.A. 2008. Nutrient Distribution within VTA Pilot Sites in Iowa and Nebraska. Amer. Soc. of Agric. and Biol. Eng. Paper No. 083982. St. Joseph, MI:ASABE. Interpretive Summary: Feedlot owners are interested in controlling runoff from their operations and protecting the environment. Traditionally, runoff is collected and stored for long periods before being applied to crop land as irrigation and fertilizer. A method that uses the runoff to raise hay without storing the water has been developed. Five sites in Iowa and six sites in Nebraska were selected to determine how well this method works. Initial condition of the hay field soil was determined to understand how effective the hay crop was at using the runoff water.
Technical Abstract: Cattle feeding operators are interested in alternative runoff control and treatment systems that eliminate the need for long-term liquid storage; however, the feasibility and sustainability of these systems is yet to be determined. Five demonstration sites in Iowa and six sites in Nebraska utilizing vegetative treatment areas (VTAs) have been constructed to determine their sustainability for feedlot runoff control. These sites represent variations in climate, site considerations (i.e., management, soil texture, topography etc.), and design. A geospatial statistical method using multi-linear regression (MLR) models combined with soil analysis was used to predict nutrient distributions and mean concentrations within the VTA. The over-all objective of the study was to report the preliminary chloride, total nitrogen (TN), and total phosphorus (TP) distribution and mean concentrations in the VTAs for two sites. Some of the VTAs appear to have a history of feedlot runoff; however, the spatial pattern from this history was complicated by site construction. Mean concentrations for chloride, TN, and TP were either calculated by the MLR model or by actual soil analysis. Predicted concentrations for each of these nutrients was less than expected from VTAs that have been in operation for many years. Difference maps showing the change in ECa values from 2006 to 2007 indicate areas of preferential flow. Preferential flow reduces the effective area of the VTA receiving runoff resulting in excessive nutrient loading along flow paths. However, these differenced maps provide valuable information for modifying VTA management to improve performance. Information from this preliminary study will be used with similar analyses during subsequent years of operation to determine overall feasibility and sustainability of vegetative infiltration basin (VIB) and VTA for controlling feedlot runoff.