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Conservation Drainage

By Staff | Jul 7, 2017

Clare Lindahl, executive director of the Conservation Districts of Iowa, distributed free RetaiN water-testing kits during a conservation drainage workshop held in the historic Owens barn south of Lake City. Nearly 50 people, including many area farmers, attended the June 28 meeting, which focused on bioreactors, saturated buffer strips and available cost-share programs to help improve Iowa’s water quality. Free consultations about potential site locations for these conservation drainage practices are available by contacting Loulou Dickey, a conservation planning intern with Ecosystem Services Exchange, at loulou@ecoexch.com





LAKE CITY – What if there were proven conservation practices that didn’t require taking farmland out of production? What if some of these practices could offer water quality solutions and provide wildlife habitat? Even better, what if there were cost-share dollars to make these practices a reality on your farm?

It’s all possible with conservation drainage.

“Managing farmland is a blessing and a responsibility,” said Clare Lindahl, executive director of the Conservation Districts of Iowa (CDI) who coordinated a conservation drainage meeting on June 28 at the historic Owens barn south of Lake City. “Fortunately, there’s a lot of technical assistance and funding available to help farmers implement more conservation drainage, including bioreactors, saturated buffers and more.”

Conservation drainage practices help reduce nitrate losses. A bioreactor works by incorporating a trench filled with wood chips. Drainage water is routed through the wood chips. Denitrifying bacteria in the wood chips convert nitrate in the drainage water into inert nitrogen gas, reducing the amount of nitrate delivered to the outlet.

“You can get a 30 percent to 60 percent nitrate reduction with bioreactors in any given year,” said Keegan Kult, an environmental scientist with the Iowa Soybean Association (ISA) who noted that ISA helped install one of the first bioreactors in the area in 2008 on Mike Bravard’s Greene County farm.

Bioreactors can be an edge-of-field conservation practice, since they can sometimes be installed alongside a fence, especially where a tile line goes under the road, Kult said. Since the wood chips and the geotextile fabric that’s placed with the woodchips are buried, the only visible sign of the bioreactor is a small control structure that sticks out of the ground.

Saturated buffers offer another option in the right terrain for conservation drainage, with nitrate reduction capabilities similar to bioreactors. These buffers work by diverting a fraction of the tile flow through riparian buffers as shallow groundwater. As the water flows through the soil in the buffer, it has a chance to interact with plants and microbes in the buffer for nitrate removal.

“While bioreactors are low maintenance, you have to excavate them after 10 to 15 years, add new wood chips and field-incorporate the old woodchips,” Kult said. “Saturated buffers are kind of a ‘set it and forget it’ system.”

Lake City-area farmer Mark Schleisman worked with the ISA to install a saturated buffer and bioreactor in the summer of 2016 on his land in the Elk Run Watershed.

“These practices are fairly simple to install, require little or no maintenance and have no negative effects on the field drainage,” he said.

Even more impressive are the water quality results. “The nitrate level in our tile water was in the 17 to 30 parts per million (ppm) range, but the nitrate levels in the drainage water that passes through the bioreactor is less than 1 ppm,” said Schleisman, who spoke at the conservation drainage seminar, which attracted nearly 50 people.

Practical considerations for conservation drainage

A bioreactor is designed to work with 6-inch to 10-inch field tiles and can drain 30 to 100 acres, Kult said. While bioreactors can cost $6,000 to $12,000, depending on their size, cost-share funds are available through programs like the Environmental Quality Incentives Program (EQIP).

Cost-share funds for various conservation drainage projects can also be accessed through a number of state and federal organizations, including some commodity organizations. “There are quite a few funding sources right now, and there’s quite a bit of money available,” said Jeremy Viles, a resource conservationist with the Natural Resources Conservation Service (NRCS).

In some cases, cost-share dollars can cover 50 to 75 percent or more of the cost of a conservation drainage project. It’s not always a fast process, however.

“It might take a year or two before you move any dirt,” said Viles, who noted that having tile maps available can expedite the process. “There are growing pains with scaling up these water quality practices across the state.”

Viles encourages farmers to visit their local NRCS office to start the conversation.

“If you’re not sure where to start, come in and talk to us to learn more about your options. We’ll help find funding for you.”

In addition, free consultations about potential site locations for conservation drainage practices are available by contacting Loulou Dickey (loulou@ecoexch.com), a conservation planning intern with Ecosystem Services Exchange in Iowa.

Water test kits available through retaiN program

In the meantime, farmers can focus on water quality by collecting data through water monitoring, Lindahl said. The process is similar to using a health-tracking device like a Fitbit, she added.

“The more data we have about our farm, the more we can improve,” she said.

A simple way to begin monitoring involves the retaiN program, a collaboration between CDI and Iowa State University Extension. Basically, farmers dip a nitrate test strip in a tile water sample and compare the test strip color to the color chart on the test strip bottle to determine a nitrate level range in parts per million (ppm).

“Farmers tell us they like the strips because they are easy to use, and the results are instantaneous and private,” Lindahl said.

The retaiN kits include 25 test strips and a test log to record results. Farmers can request retaiN kits at retainiowa.com.

Lindahl encourages farmers to monitor nitrate levels and explore conservation drainage practices for their acres.

“These practices offer a good balance between crop production and water quality,” Lindahl said.

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