This undergraduate research program is investigating nutrient management on the University of Delaware Newark Farm. Its objective is to identify management practices which will minimize nutrient movement into groundwater and local streams.
The main University Farm is located immediately south of the main University campus. The smaller Webb Farm is located immediately to the east, across Route 72. Both farms span a divide between the White Clay Creek Watershed to the north and the Christina River Watershed to the south. The color-infrared photograph below was taken in April, 1992. It was scanned and geo-referenced to UTM (NAD 1983) coordinates for congruence with other GIS data layers.
Soil survey maps were scanned, geo-referenced and processed to create a digital soils map of the farm. Predominant soils are Matapeake silt loam (yellow to light green reflecting increasing slope), Elton silt loam and sandy loam (mid-greens), Sassafras sandy loam (dark greens) and Woodstown loam (blues). Field boundaries and other features are superimposed in black.
Vector hypsography (elevation countour line) data were used to create a 10x10-meter resolution digital elevation model (DEM) for the farm. Slope and aspect maps are then calculated from the DEM. The hill-shaded DEM displayed below was created as a composite of elevation (hue) and aspect (intensity). Field boundaries are superimposed in black. The map below shows the drainage system inferred from the elevation data using the GRASS r.watershed module, superimposed in red.
r.watershed was used to identify drainage basins and sub-basins 50 acres or larger. The colors of the drainage network represent the natural logarithm of the calculated flow volume passing through each cell from a uniformly-distributed rain event. The red and magenta portions of the network coincide fairly closely with small surface streams. The remainder of the network represents lesser overland or sub-surface accumulations.
We indexed phosphorous runoff from 28 fields on the two farms based on P concentrations from soil test data. r.watershed was used to calculate P flows from these fields only. The following map displays the logarithm of inferred P concentrations in runoff. The principal P runoff "hot spot" is the west dairy pasture.
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