Spatial Nutrient Distribution of VTA Pilot Sites in Iowa

Abstract

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 utilizing vegetative treatment areas (VTAs) have been constructed to determine their sustainability for feedlot runoff control. These sites represent an array of climate, site considerations (i.e. topography, soil texture, management, 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. The over-all objective was to report the preliminary chloride, total nitrogen (TN), and total phosphorus (TP) nutrient distribution and mean concentrations in the VTAs for two sites. Some of the VTAs appear to have a history of feedlot runoff; however, the extensiveness of this history is complicated by site construction. Mean concentrations for chloride, TN, and TP were either calculated by MLR model or by actual soil analysis. The determined concentrations for each of these nutrients were at the lower end expected from VTAs that have been in operation for many years. When MLR model fit was sufficient for determining predicted nutrient distributions, these distributions were predominately clustered at the low end expected by VTAs with many years of operation. Preliminary analysis appears to have provided sufficient base-line understanding as to the status of these VTAs at the on-set of their operation. This information will be used with similar analyses after subsequent years of operation to determine over-all VTA feasibility and sustainability for controlling feedlot runoff.