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United States Department of Agriculture

Agricultural Research Service

Title: Ground Water Nitrate-N Concentrations on a Demonstration Watershed in the Eastern Coastal Plains

Authors
item Stone, Kenneth
item Hunt, Patrick
item Johnson, Melvin
item Matheny, Terry

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 6, 1997
Publication Date: N/A

Interpretive Summary: Nonpoint pollution from agriculture has been a major concern, particularly where intensive operations exist near environmentally sensitive waters. A Water Quality Demonstration project initiated in Duplin County, NC, on the Herrings Marsh Run watershed was intended to improve the quality of water in streams and ground water near farms and ranches. Scientists are trying to find ways to reduce the amounts of fertilizer and pesticides that leak into streams and ground water. While farmers change from traditional to more environmentally friendly methods, scientists are monitoring ground water on several farms in the watershed. Monitoring wells were installed in and around farmers' fields to evaluate the ground water quality. Most of the farms have good ground water quality. Fields on a few farms have ground water that occasionally does not meet drinking water standards. The farms with the worst water quality lie near several hog and poultry farms. One farm with poor water quality is improving their ground water quality by expanding the waste disposal area to be in compliance with more recent guidelines.

Technical Abstract: Nonpoint pollution from agriculture has been a major concern, particularly where intensive operations exist near environmentally sensitive waters. A Water Quality Demonstration Project was initiated in 1990 to address these and other agricultural concerns on environmental quality and to facilitate the voluntary adoption of improved management practices. One hundred and five ground water monitoring wells were installed on 21 farms in the Herrings Marsh Run watershed in Duplin County, NC. Farms were selected to represent the major farming practices on the watershed. Nitrate-N concentrations were below the maximum contaminate level (MCL) of 10 mg/L on all but 4 farms. Of these four farms, only one had concentrations that exceeded 20 mg/L. This farm had an undersized and overloaded spray field. After the spray field was expanded and application rates reduced, ground water concentrations declined, but they remained above 10 mg/L. Other farms with similar practices had ground water nitrate-N concentrations less than 20 mg/L throughout the study period. Ground water nitrate-N concentrations under row crops were below 10 mg/L on all but one farm. A trend analysis showed that most farms with concentration less that 10 mg/L had no detectable increase in nitrate-N concentration during the study.

Last Modified: 11/24/2014
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