Water Resources Research Act Program

Details for Project ID 2012SD215B

Evaluating the Nitrate-Removal Effectiveness of Denitrifying Bioreactors

Institute: South Dakota
Year Established: 2012 Start Date: 2012-03-01 End Date: 2014-02-28
Total Federal Funds: $39,286 Total Non-Federal Funds: $78,614

Principal Investigators: Jeppe Kjaersgaard, Christopher Hay, Todd Trooien

Project Summary: Subsurface (tile) drainage on agricultural land with poor natural drainage allows more timely field operation access and contributes to improved crop yields. While properly designed and installed subsurface drainage typically reduces sediment and phosphorus losses, many studies show that subsurface drainage enhances the movement of nitrate-nitrogen to surface waters. Nitrogen is an essential plant nutrient, but excess nitrogen leads to eutrophication and hypoxic conditions in aquatic ecosystems, particularly in estuaries. Many scientists suspect that nitrogen from agricultural runoff in the Mississippi River Basin is a leading contributor to the annual hypoxic zone in the northern Gulf of Mexico. Additionally, high concentrations of nitrate-nitrogen in drinking water supplies pose a health hazard, especially for infants and pregnant women, and are expensive to treat. This creates a critical need for strategies that minimize nitrate losses through subsurface drainage of agricultural land. While improved management of nitrogen fertilizer and animal manure is one important method for reducing nitrate losses, it is often not enough: therefore, water quality goals for nitrate require additional, off-field drainage water and nutrient management methods. Our long-term goal is investigating, developing, evaluating, and transferring practices that maintain the benefits of agricultural subsurface drainage while minimizing unwanted environmental impacts. The overall objective of this project is demonstrating and evaluating denitrification drainage bioreactors placed on the edge of fields to reduce nitrate loads from subsurface drainage systems to receiving waters in eastern South Dakota. Several studies show bioreactors as effective methods for reducing nitrate concentrations of drainage flow (e.g. van Driel et al., 2006; Appleford et al., 2008; and Jaynes et al., 2008). Van Driel et al. (2006) found bioreactors remove nitrate at rates of an order of magnitude greater than treatment wetlands and use only 10% of the area typically required for constructed wetlands (Kovacic, et al., 2000). However, bioreactors for treatment of drainage water are still an emerging technology, and a recent focus group study conducted among drainage professionals indicated a need for further information and demonstration to establish their effectiveness (Lewandowski, 2010). This proposal will cover the assistantship and tuition for one graduate student for the first of two years of a graduate program in Agricultural and Biosystems Engineering. We anticipate submitting a second proposal for the Water Resources Institute USGS 104b grant program (or other program, as applicable) for FY 2013, also, to cover the second year of the assistantship. The work we propose in this proposal takes advantage of the unique opportunity to utilize the infrastructure and bioreactor installations already covered though other funds to train a graduate student in problem solving using a well-defined yet complex water quality problem.