Impact of Poultry Mortality Pits on Farm Groundwater Quality

Abstract

Results of a 15-county survey revealed that intensive animal agriculture may impact shallow groundwater resources. Objectives of this study are to assess water quality on poultry farms and determine if there is a relationship between waste disposal practices and groundwater quality. Twenty poultry farms representing concentrated areas of commercial poultry production and four major soil provinces were evaluated using site assessments, questionnaires, electromagnetic (EM) survey readings, and chemical and microbiological analysis of domestic well water. Based upon the EM survey results, five farms were instrumented with lysimeters and test wells to determine possible nutrient and microbiological movement to groundwater. Site evaluations revealed that 10 of the 47 (21 %) domestic wells did not have appropriate well head protection to prevent surface water contamination. Five of the 47 (11 %) wells were located downslope and/or within 100 ft. of a nitrogen source other than pits and averaged nitrate-N (N03-N) levels above background (3 ppm). Thirty-eight percent had elevated coliform levels and 10.6% contained Salmonella in at least one sample during the sampling period. EM surveys and monitoring data indicated that nutrients migrate less than 100 ft. laterally down gradient from the pits. Poultry mortality pits on the 20 farms did not appear to elevate nitrate levels above background. Groundwater nitrate-N levels were higher on farms containing uncovered litter stacks. Preliminary results indicate that uncovered litter stacks may have a greater impact on groundwater quality than poultry mortality pits. Additional testing on various soil types is needed.