THE USE OF AGRICULTURAL BEST MANAGEMENT PRACTICES TO REDUCE NITROGEN LOADING TO THE SOUTH RIVER, NORTH CAROLINA

摘要

In 1999 a 5 ha tidal wetland was constructed on Open Grounds Farm (OGF) in eastern North Carolina as a best management practice (BMP) in order to remove nutrients (N+P), sediment and pathogens in surface water draining from an 809 ha area of OGF. The farm is an 18,210 ha row crop farm located in the Neuse River Watershed. The wetland area is 5.1 ha with alternating sections of emergent marsh and open water. The design includes 19 wetland cells, each approximately 30 x 30 m, and adjacent ponds of equal size. The wetland cells were planted in the summer of 1999 with one of four native plant species including Spartina alterniflora, Spartina patens, Cladium jamaicense, and Juncus roemerianus. Nutrient loading and removal were determined from twice monthly nutrient collection at 24 sites within the wetland. Data from 1999-2002 show the constructed wetland is effective at the removal of inorganic nutrients, nitrate and, ammonium. Dissolved organic nitrogen removal occurred during the first two years of monitoring but was negative during the remaining time period. These data indicate that the constructed wetland, in conjunction with other best management practices, significantly increased the quality of the surface- water runoff from agricultural operations.