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Demonstrating the Nitrogen-Removal Effectiveness of Denitrifying Bioreactors for Improved Drainage Water Management

Subsurface (tile) drainage on agricultural land with poor natural drainage allows timelier 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.

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 denitrifying bioreactors placed on the edge of fields to reduce nitrate loads from subsurface drainage systems in eastern South Dakota.

We will install 4–6 bioreactor demonstration sites in eastern South Dakota and monitor their performance in removing nitrate. The sites will be open for at field days and the monitoring results will be publically available.

The work involves researchers from the Department of Agricultural and Biosystems Engineering and Water Resources Institute at SDSU and is supported by a grant from the USDA Natural Resources and Conservation Service. Additional support comes from SDSU, East Dakota Water Development District, the South Dakota Farm Bureau, the South Dakota Soybean Research and Promotion Council and the Vermillion Basin Water Development District.

Contact information
Dr. Jeppe Kjaersgaard, SDSU Water Resources Institute
Dr. Chris Hay, Department of Agricultural and Biosystems Engineering, SDSU
Dr. Erin Cortus, Department of Agricultural and Biosystems Engineering, SDSU
Dr. Todd Trooien, Department of Agricultural and Biosystems Engineering, SDSU

Tractor trenching in drain tile





Drain tile model at Farmest Booth