Alternative Agricultural Ditch Designs, NO3-N Treatment, Construction Costs, and Benefits—Mower County, Minnesota, USA

Krider, Lori; Kramer, Geoff; Wilson, Bruce; Magner, Joe; Lazarus, William F.; Hansen, Brad M. S.; Nieber, John L.

doi:10.17265/2162-5263/2022.06.002

Cited by 1 publication

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“…In recent years, new edge-of-field practices such as strategically placed treatment wetlands and saturated buffer zones have provided NO 3 -N attenuation. Further, channel re-construction with two-stage ditches (TSDs) can reduce NO 3 -N [37,38]. Research findings indicate that this alternative drainage system, featuring a two-stage ditch, a rock trench, a rock inlet and two in-ditch linear treatment systems, is more naturally stable and capable of absorbing NO 3 -N while providing a healthy ecosystem.…”

Section: Conclusion and Recommendationsmentioning

confidence: 99%

The Evaluation of a Novel Denitrifying Woodchip Bioreactor: Fairmont, MN, USA

Xu,

Holmberg,

Magner

2024

Nitrogen

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The risk of nitrate contamination became a reality for Fairmont in Minnesota, when water rich in NO3-N exceeded the drinking water standard of 10 mg/L. This was unexpected because this city draws its municipal water from a chain of lakes that are fed primarily by shallow groundwater under row-crop land use. Spring soil thaw drives cold water into a subsurface pipe where almost no NO3-N reduction occurs. This paper focuses on NO3-N reduction before the water enters the lakes and no other nitrogen management practices in the watershed. A novel denitrifying bioreactor was constructed behind a sediment forebay, which then flowed into a chamber covered by a greenhouse before entering a woodchip bioreactor. In 2022 and 2023, water depth, dissolved oxygen, and temperature were measured at several locations in the bioreactor, and continuous NO3-N was measured at the entry and exit of the bioreactor. The results showed better performance at a low water depth with lower dissolved oxygen and higher water temperature. The greenhouse raised the inlet temperature in 2022 but did not in 2023. The forebay and the greenhouse may have impeded the denitrification process due to the high dissolved oxygen concentrations in the influent and the stratification of dissolved oxygen caused by algae in the bioreactor.

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Section: Conclusion and Recommendationsmentioning

confidence: 99%