Principal Investigator: D. E. Brune (University of Georgia)
Principal Investigator: H. D. Gunther (University of Georgia)
Principal Investigator: David E. Radcliffe (University of Georgia)
Principal Investigator: D. J. Drommerhausen (University of Georgia)
Sponsor: GWRI
Start Date: 1994-04-01; Completion Date: 1994-04-01;
Keywords: Nitrate, Animal Waste, Dairy, Electromagnetic Conductivity.
Description:
Nine dairies in north Georgia were surveyed using a ground electromagnetic (EM) conductivity meter to determine the source of high nitrate in dairy wells in the region. Ground EM conductivity increases with water and soluble salt content and has been used to map contaminant plumes from landfills and animal waste lagoons. A consistent pattern of EM readings was found at all of the dairies. There was evidence of seepage from lagoons at four of the seven dairies. However, it appeared that a more likely source of contamination in the wells was the unpaved loafing areas near the milking barns. EM readings in these areas were typically 15-20 mS m-l, whereas background readings were near 5 mS m-1. To supplement the EM readings, a total of seven groundwater observation wells were installed, five at one dairy (MO-l) and one each at two other dairies (MO-6 and PU-l). The wells at MO-l were installed at five locations: one next to the dairy barn, three in the loafing area, and one beyond the loafing area. Nitrate contents in the three wells in the loafing area ranged between 74- 96,60-105, and 83-120 mg L-1 N03-N. Concentrations in the well next to the barn and beyond the loafing area were between 12-43 and 12-16 mg L-\ respectively. The wells at MO-6 and PU-2 were located in loafing areas and had N03-N concentrations ranging from 53-83 and 105-135 mg L-1. We conclude that the loafing areas at the dairies we surveyed are a likely source of groundwater contamination by nitrate because of the high animal density and consequent high waste deposition rate.