Saturated Buffer: A water level control structure is installed near the outlet of a tile line, but within or immediately adjacent to an existing stream buffer. A portion of the water is diverted into a tile line parallel to the stream and within the buffer. Excess nitrate in the tile flow is converted to harmless nitrogen gas in the soil of the stream buffer due to organic matter and low oxygen.
Saturated buffers are a relatively new practice for improving water quality. This practice has considerable potential due to its reliability, effectiveness and low cost. US Department of Agriculture Natural Resources Conservation Service has approved an interim practice standard.
The advantages of saturated buffers include: low maintenance, relatively simple to install and a reasonable cost. The challenges for this practice include: site specific soil investigations are required to determine if the practice can be applied; interim practice standard complicates using this practice within Conservation Reserve Program areas; very few people have experience with site assessment, design, and installation; and a buffer of perennial vegetation is needed. The site assessment and design must assure that impacts of impeded drainage on the cropland upstream are minimal and that streambank soils will remain stable with prolonged saturation.
Presentation on saturated buffers and Prairie STRIPS
Cleaning Iowa’s waters with saturated buffers
Saturated Buffer Fact Sheet