Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/26/1997
Publication Date: N/A
Technical Abstract: An objective of the USDA Water Quality Demonstration Project on the Herrings Marsh Run in Duplin Co, NC, was to improve water quality via voluntary methods. To this end, a 3.3-ha in-stream wetland was established in an abandoned pond at the exit of the 425-ha watershed. Before establishment of the wetland, the stream had ammonia-N and TKN means sof no more than 1 mg/L, but the nitrate-N mean was 7 mg/L. The wetland dropped nitrate-N concentration in the stream to < 1 mg/L, and dramatically lowered nitrogen export during the warmer months. However, during the cooler months, the nitrogen load was only slightly reduced so that the annual mass reduction was about 65%. In order to obtain more nitrate-N reduction during the cooler months, an additional 1-ha in-stream wetland was added. The new wetland had minimal effect on ammonia-N and TKN, but it reduced nitrate-N from 11 to 8 mg/L.