Start Date: Oct 17, 2013
End Date: Aug 31, 2016
At least two saturated riparian buffers will be used in the study. One buffer is a three-zone design with a zone of trees next to the stream, followed by a grass-shrub zone, and a zone of grasses on the uphill side of the buffer. The other buffer has a single uniform zone of switch grass. Tile flow from a field used for corn/soybean production will be intercepted and some of the flow infiltrated as shallow groundwater at the top of the buffers. Flow and nitrate concentrations in the tile drainage will be measured continuously. The fate of the nitrate in the buffers will be followed by sampling the groundwater within the buffers from multiple transects of wells spanning the width of the buffers. Denitrification within the buffer soil will be measured at multiple times and locations. Since denitrification rate is difficult to measure, we will use a range of in situ methods, including push-pull and radio labeled methods, as well as laboratory incubation methods using intact soil cores from the buffers. The production of N2O will be measured in multiple vented chambers placed within the buffer and by measuring dissolved N2O in groundwater within the buffer.