Water balance of a dairy loafing lot using geotextile and its impact on water quality

ABSTRACT:

To lessen soil erosion due to high animal stocking rates on small Georgia dairies, the Natural Resources Conservation Service (NRCS) recommends a system that utilizes geotextile material covered with crusher run gravel as a soil cover in high animal traffic areas. Our objective was to determine the runoff and leachate characteristics of a typical system. At a 60-cow dairy in Oglethorpe County, Georgia, a loafing lot was constructed on a Pacolet sandy loam soil (clayey, kaolinitic, thermic, Typic Kanhapludult). Tile drains were installed at 0.65 m (26 in) depth on 7.5 m (25 ft) spacing. Approximately 18 percent of the rainfall became surface runoff. Surface runoff water typically contained levels of NH₄-N and PO₄-P that exceeded the Environmental Protection Agency (EPA) guidelines for surface water. Approximately 32 percent of the rainfall became drainage water that moved below the top 1.5 m (60 in) soil profile and had nitrate levels ranging from 10 to 40 mg NO₃-N L⁻¹. Our results indicate that surface water running off of these sites should be impounded in a lagoon or similar structure and these systems should not be located in areas where groundwater contamination is a concern.