Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/1998
Publication Date: N/A
Interpretive Summary: Agricultural nonpoint source pollution has been a major water quality concern, particularly where intensive operations exist near environmentally sensitive waters. To address these concerns, a water quality project was initiated in the Coastal Plain of North Carolina. A swine farm in a monitored watershed expanded its operation from 3,300 to more than 14,000 animals. Groundwater on this farm and stream water downstream from the farm were studied. Seven wells were installed in the field and surrounding riparian area. Three of these wells had increasing nitrate concentrations. Stream nitrate concentrations increased during the colder months of the year after the operation expanded, but remained the same during the warmer months. Stream ammonia concentrations increased after the farm was expanded. Stream ortho-phosphate concentrations remained approximately the same. The riparian zone appears to be reducing nitrate concentrations in groundwater and nutrient loadings in an adjacent stream.
Technical Abstract: Nonpoint source pollution from agriculture has been a major concern, particularly where intensive agricultural operations exist near environmentally sensitive waters. To address these concerns, a water quality project was initiated in Duplin County, NC in the 2044-ha Herrings Marsh Run watershed. A swine farm within this monitored watershed expanded its operation from 3,300 to more than 14,000 animals. Groundwater nitrate-N increased significantly in three of the seven wells located adjacent to the spray field and in the adjoining riparian zone. Stream nitrate-N concentrations have increased after the expansion of the swine operation in the colder months, but concentrations have remained approximately the same during the warmer months. Stream ammonia-N baseline concentrations after expansion have increased as well as the frequency and magnitude of ammonia-N concentration spikes. Ortho-phosphate concentrations in the stream water have been relatively consistent over the study period. The riparian zone is reducing the impact of spray field groundwater nitrate concentrations and ammonia loadings in an adjacent stream.