Bioreactor technology emerges as powerful tool for nutrient stewardship

Geneseo Republic


For Illinois Press Association

WOODSTOCK – Corn and soybean farmer Michael Ganschow was an easy recruit for Lauren Lurkins, the Illinois Farm Bureau’s director of environmental policy, as she was encouraging farmers to install woodchip bioreactors on their farms.

“I met Lauren in 2016, and less than two years later, she’s showing up at my farm with equipment, digging a hole and filling it with woodchips,” Ganschow said to a crowd of farmers, agriculture leaders and state and national representatives and staff Tuesday morning at the latest in the IFB’s series of Nutrient Stewardship Field Days.

Ganschow is a sixth-generation farmer in Bureau County, and his grandfather was among the first Illinois farmers to implement no-till practices.

“Conservation has always been a big part of what we do,” he said.

A woodchip bioreactor might sound like something straight out of Marvel Comics. In reality, it’s essentially a trench filled with woodchips that filter out nitrates that would otherwise pollute tile drainage water, and then streams, and then the Mississippi River, and then the Gulf of Mexico. You get the idea.

Jeff Kirwan, a Mercer County farmer, speaks during an event Tuesday in Woodstock about the value of a woodchip bioreactor to his operations. He said he’s considering installing a second bioreactor on his farm.

Once a pipe system directs drainage water through control structures and into the bioreactor, bacteria in the woodchips eat the nitrates from fertilizers that go unused by crops, and then convert those nitrates into nitrogen gas that’s just as safe for the environment as the 78 percent of stable nitrogen in the air we breathe.

“It sounds like something out of ‘Iron Man,’ but really it’s a trench full of woodchips with a little bit of plumbing,” said Laura Christianson, assistant professor with the University of Illinois’ Department of Crop Sciences, which monitors 15 of the 50 or so bioreactors around the state.

The McHenry County Conservation District, in partnership with the local and state Farm Bureaus, installed a 30-by-30-foot bioreactor last summer just north of Woodstock, where nearly 100 people gathered Tuesday to learn about the technology.

State Reps. Steve Reick, R-Woodstock, and Tom Weber, R-Fox Lake, attended the event, along with staff from Lt. Gov. Juliana Stratton’s office and the office of U.S. Rep. Lauren Underwood, D-West Chicago.

“Our farmers are always asking three questions: How much does it cost. How hard is it to maintain it? And does it work?” Lurkins said.

First things first, it cost nearly $10,000 to build the McHenry County bioreactor, and there will be another investment 10 or 15 years down the road, when the woodchips need replacing – or recharging, as Christianson calls it.

But does it work? Absolutely, according to the water samples MCCD volunteers had collected, frozen and sent to Christianson for analysis since May 1.

The bioreactor converted about 80 of the 150 pounds of nitrate into nitrogen gas – roughly 53 percent.

“It’s working, and it’s working well,” Christianson said, adding that the state’s bioreactors on average remove about 25 percent of nitrates.

Most of those other sites followed the federal government’s rectangular blueprint for a bioreactor, which local Natural Resource Conservation Service offices use when they help farmers design their trenches.

Christianson and her team, weighing myriad factors at the McHenry County site, custom-designed a square trench that works like a dream.

The bioreactors are relatively new technology, so it’s being rapidly developed through experimentation. Ganschow’s trench, for instance, is wide open. Most others are sealed with a plastic sheet and then graded, so you might not know you’re standing on top of it.

He was joined on a panel Tuesday by Jeff Kirwan, an IFB Board member who’s considering installing a second bioreactor at his Mercer County farm near the Quad Cities, and a third corn and soybean farmer, Brian Corkill, whose Henry County farm splits the distance between Peoria and Moline.

Whereas Ganschow and Kirwan had plenty of inside knowledge because of their close work with the bureau, Corkill began the process the way Christianson recommended all farmers do: He reached out to his local NRCS office.

The bioreactor was the next logical step for Corkill, given his commitment to stewardship through no-till farming, cover crops, and only fertilizing as much as necessary.

Reick asked the panel how many woodchip bioreactors would be needed to reach the nation’s conservation goals.

Christianson said it will take 60,000 bioreactors and better stewardship across the board to turn the tide.

“We need every practice, and wide use of every practice,” she said. “But it starts one bioreactor at a time.”

This story was distributed through a cooperative project between Illinois Farm Bureau and the Illinois Press Association. For more food and farming news, visit