water quality monitoring, agriculture, pollution, poultry production
In recent years, the rapid growth of poultry and hog production in Arkansas has caused concern regarding nitrate contamination of the ground water. In the study area of Pike and Howard Counties, the number of hogs has increased from 3,300 hogs in 1970 to 75,000 hogs in 1990. Poultr¥ production for the area has increased from 38,933,000 per year 1n 1970 to 62,774,000 per year in 1990. As animal production increases, so does the amount of animal waste that must be disposed. Hog production is of particular concern. Typical hog operations store concentrated animal waste in lagoons prior to land application. If the lagoons are improperly constructed and leak, they can contaminate ground water with bacteria and nitrate. Disposal of chicken litter on pastureland is also a significant source of 9round water nitrate. In response to these concerns, a study of n1trate concentrations in rural water wells was conducted for Pike and Howard Counties during "wet" and "dry" seasons in 1991. Approximately fifty samples were collected from each county and analyzed for nitrate as well as other chemical parameters. Pike and Howard Counties are divided into two distinct physiographic regions; the Ouachita Mountains and the Gulf CoastalPlain. Comparisons of nitrate concentrations indicates that the Gulf Coastal Plain portion of the study area may be more susceptible to surface contamination than the Ouachita Mountainportion. Average mean nitrate plus nitrite (NO3-N) values for the Gulf Coast portion of the study area was 1.06 mg/L as compared to 0.59 mg/L for the Ouachita Mountains. Also, nitrate data from a 1955 study indicates that the increased animal production in pike and Howard Counties corresponds with increased levels of groundwater nitrate. In 1955 the average mean NO3-N value was 0.26 mg/L (Gulf Coastal Plain area) as compared to 1.06 mg/L in 1991. Wet season average mean NO3-N values for the Gulf Coast region (0.22mg/L) and the Ouachita Mountain region (0.06 mg/L) were higher than dry season NO3-N values (0.16 mg/L and 0.02 mg/L,respectively). Nitrate levels in ground water for pike and Howard Counties were all below the 10 mg/L NO3-N drinking water standard.
Thornton, Travis and Steele, Kenneth F.. 1992. Reconnaissance Survey of Nitrate Concentrations in Ground Water in Howard and Pike Counties, Arkansas. Arkansas Water Resources Center, Fayetteville, AR. MSC085. 33