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United States Department of Agriculture

Agricultural Research Service

Research Project: Denitrification Within Saturated Riparian Buffers Re-Designed to Remove Nitrate from Field Tile Drains Project Number: 5030-13000-010-29
Project Type: Reimbursable

Start Date: Oct 17, 2013
End Date: Aug 31, 2016

Objective:
Measure the mass of nitrate that is redirected into riparian buffers from field tile drain outlets, follow the fate of this nitrate as it seeps through the buffers, quantify the mass of nitrate that is removed in the buffers, and quantify denitrification of nitrate and the production of N2 and N2O gas within the buffer as a function of buffer location and season.

Approach:
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.

Last Modified: 11/23/2014
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