Movement of Nitrogen through an Agricultural Riparian Zone: 1. Field Studies

Forested riparian areas are believed to be important for reducing nonpoint source pollutants. These areas along streams, lakes, and wetlands have been reported to trap sediment and nutrients and enhance denitrification. Past research on the effectiveness of riparian areas has been based on existing forests rather than restored areas. An experiment using the paired-watershed design was established in northeastern Connecticut during 1992 to determine the water quality effects of reforestation on a riparian zone currently cropped in maize. Water quality fluxes in precipitation, overland flow, soil solution, groundwater, and streamflow were determined. Results indicate that this 35 m wide riparian zone had little attenuating influence on N concentrations in groundwater based on NO3−N concentrations and NO3−N:C1 ratios. The primary N flux to the stream was in the groundwater. Denitrification did not appear to be a major process operating in this system. Reforestation of this riparian buffer should result in improved surface and groundwater quality.