Monitoring alternative feedlot runoff control technology effectiveness, especially vegetativetreatment systems (VTS), is of interest to both cattlemen and regulatory agencies. Producers haveconstructed VTS in several mid-western states under an agreement with the Iowa Cattlemen Associationand the Natural Resource Conservation Service. This paper describes a method of monitoring VTSperformance as applied to a system constructed at the U.S. Meat Animal Research Center (USMARC),Clay Center, Nebraska. Soil conductivity maps were generated on two separate dates separated byapproximately 14 months. A program, ESAP, developed by the Soil Salinity Lab at Riverside, CA wasused to: 1) determine soil core locations, 2) generate nutrient specific predictive maps based oncombined soil core data and a soil conductivity map using multiple linear regression methods. TheESAP program suite provided estimates of the primary variable distribution across the VTS based ontwelve core sites and high density soil conductivity (ECa) data for both sample dates. Prediction data forthe two dates were compared by differencing gridded data of each date. The difference map illustratesmanagement changes that occurred during the interval between the two survey dates. Methodologiesdescribed here demonstrate the capabilities of this analysis approach as applied to VTS in operation foreight years. The methods are sensitive enough to measure subtle management changes but robustenough to evaluate overall performance. These same methods have been applied to multiple sites inIowa and have been reported previously (Woodbury et al., 2007).
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