Figure 1. Saturated buffer lateral line installation in Moody County.
Written collaboratively by Scott Cortus (Environmental Research Coordinator, S.D. Water Resources Institute) and David Kringen.
Saturated buffers can be an effective technique for removing nitrates from tile drainage water before they are released into waterways. A saturated buffer is essentially a perennially-vegetated riparian buffer with a raised water table. To raise the water table, drainage water is diverted through drainage tile that is placed parallel to the stream and below the riparian buffer. A control structure diverts a fraction of the drainage water flow through the lateral tile lines, and releases the water into the buffer as shallow groundwater. The saturated buffer can then reduce the nitrate concentration and load through (1) direct uptake of nitrogen by the vegetation in the buffer, (2) converting nitrate-nitrogen into harmless nitrogen gas that is released back into the atmosphere, and (3) reducing the water volume entering the stream through water uptake by the vegetation.
Recent Saturated Buffer Projects
During the summer of 2016, staff from the SDSU Department of Agricultural & Biosystems Engineering and the SD Water Resources Institute installed two field-scale saturated buffer systems in Minnehaha County and Moody County. The systems will be monitored to determine the buffers’ nitrate removal effectiveness from tile drainage water. Data collection at the saturated buffer sites started in late summer 2016 but no results are available yet.
About the South Dakota Water Resources Institute
The South Dakota Water Resources Institute (WRI) at South Dakota State University provides leadership on evolving water concerns and problems being faced by South Dakota citizens through research, educational opportunities for students and professionals, and community outreach.
The Institute is a is a federal–state partnership that:
- Plans, facilitates, and conducts research to aid in the resolution of State and regional water problems.
- Provides for the training and education of scientists and engineers through their participation in research and outreach.
- promotes technology transfer and the dissemination and application of water related information.
- Provides for competitive grants for students and researchers.
Authorized by Congress as one of the nation’s 54 water resources research institutes, we also connect the research expertise at South Dakota State University to water related problems at the local, regional or national level. The Institute is affiliated with the University’s College of Agriculture and Biological Sciences, Department of Agricultural and Biosystems Engineering and the South Dakota Agricultural Experiment Station.