SDSU Researchers Say Saturated Buffers Are Good For Nitrate Removal

May 13, 2019

South Dakota State University researchers evaluated the use of saturated buffers in eastern South Dakota through a three-year, $75,000 Conservation Innovation Grant from the U.S. Department of Agriculture’s Natural Resources Conservation Service.
Credit SDSU

South Dakota State University researchers say saturated buffers provide a cost-effective way to remove water.

The three year study shows 90 percent of nitrate removal is possible in the right places.

In 2015 and 2016, SDSU researchers installed two saturated buffers, one near Flandreau and Baltic. Both had riparian buffers near waterways, which filter nutrients from surface runoff.

A saturated buffer is one where water from a drain tile flows slowly through a vegetation strip where plants and microbes can convert nitrates to nitrogen gas and plants use nitrates before it reaches surface water.
Slope for the buffer must be just right.

Rachel McDaniel is an assistant professor and water resource engineer at South Dakota State University.
She says a saturated buffer is similar to a riparian area.

“On the surface all you’ll see is a buffer adjacent to a stream as well as maybe a control structure that then diverts flow into that buffer through the tile system,” McDaniel says.

McDaniels says they had a range of nitrate removal rate, anywhere from 65 to 90 percent.

Nitrates impact local water quality, as well as collect in the Gulf of Mexico. Those can cause algae blooms and dead zones for fish.

Professor Todd Trooien says a saturate buffer is one of the tools farmers can use to reduce nitrate concentrations sent down stream from a drainage system.

“It’s not the only tool but it is one of them that works pretty well and is cost effective if you have the correct site, if your site meets some criteria,” Trooien says.

More information available at a workshop set for mid-July on conservation drainage practices.