2014 journal article
GROUNDWATER NITRATE CONCENTRATION REDUCTIONS IN A RIPARIAN BUFFER ENROLLED IN THE NC CONSERVATION RESERVE ENHANCEMENT PROGRAM
JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, 50(3), 653–664.
Abstract Riparian buffers have been used for many years as a best management practice to decrease the effects of nonpoint pollution from watersheds. The NC Conservation Reserve Enhancement Program ( NC CREP ) has established buffers to treat groundwater nitrate‐nitrogen ( NO 3 − ‐N) from agricultural sources in multiple river basins. A maturing 46 m wide riparian buffer enrolled in NC CREP was studied to determine its effectiveness in reducing groundwater NO 3 − ‐N concentrations from a cattle pasture fertilized with poultry litter. Three monitoring blocks that included groundwater quality wells, water table wells, and soil redox probes, were established in the buffer. NO 3 − ‐N concentrations decreased significantly across the buffer in all of the monitoring blocks with mean reductions of 76‐92%. Many biological processes, including denitrification and plant uptake, may have been responsible for the observed NO 3 − ‐N reductions but could not be differentiated in this study. However, mean reductions in Cl − concentrations ranged from 48‐65% through the blocks, which indicated that dilution was an important factor in observed NO 3 − ‐N reductions. These findings should be carefully considered for future buffer enrollments when assigning nitrogen removal credits.