Study shows saturated buffers effective at removing nitrates form tile drainage
A project to monitor the effectiveness of saturated buffers has produced encouraging results.
The monitoring project, done by the Agricultural Drainage Management Coalition (ADMC) and Dan Jaynes with the U.S. Department of Agriculture’s National Laboratory for Agricultural & the Environment, monitored nine saturated buffers in Iowa, Minnesota and Illinois. It found that all nine sites were consistent in reducing nitrate concentration from the main line of the drainage system to the stream-side test well.
To create a saturated buffer, a tile line is diverted into a vegetated, riparian buffer. As saturation of the buffer occurs, along with lateral water movement through the buffer, the vegetation and denitrifying soil organisms remove nitrates from the water, reducing the nitrates discharged to the streams.
This project monitored sites intentionally that included a variety of soil types, buffer vegetation, surface topographies, and ditch/stream channel depths. The monitoring timeline included a period from September 2016 through February 2017, yielding six months of flow and nutrient samples from the nine different test sites.
This new data, along with other studies, support the use of saturated buffers as a credible nitrate load reduction practice. In addition, the cost per pound of nitrate removed is low compared to other nitrate removal practices.
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