BY BARB BAYLOR ANDERSON, Special to FarmWeekNow.com
It might look like Colby Hunt dumped a row of woodchips in the grass strip along the edge of one of his fields. But in reality, the woodchips are part of an innovative strategy that, based on preliminary findings, will help continue the conservation tradition on the Hunt family farm.
Hunt, who farms near Blandinsville and is president of the McDonough County Farm Bureau, shared at the Nutrient Stewardship Field Day held at his farm, June 21, his impressions about the woodchip bioreactor that has been installed as an edge-of-field conservation practice.
“We always want to do what we are doing even better, so we put in the bioreactor to improve on our stewardship efforts,” said Hunt. “My grandpa and dad started no-tilling and strip-tilling in the 1980s. They were also believers that every year you don’t use field tile is a year you ‘pay’ for it. So, since we have good draining soils, this was a way to replace a pond and silted-in dam.”
Hunt began looking into adding a woodchip bioreactor in 2017. With the pandemic, supply chain challenges, fewer workers and less equipment available, the project was completed in the fall of 2021. Austin Ramirez, Illinois Natural Resources Conservation Service (NRCS) ag engineer working with the Hunts, recommended pipe drainage and a dropdown structure replace the pond to go along with the woodchip bioreactor constructed on higher ground.
“The field is 40 acres and has subsurface drainage. By adding the bioreactor as a conservation practice correctly on what is a well-suited site, the Hunts get top performance,” Ramirez said.
Hunt’s woodchip bioreactor is 15 feet by 60 feet and handles 0.117 cubic feet per second (approximately seven-eighths of a gallon and about 75,000 gallons per day), to reduce nitrates flowing from the field. A control structure diverts water into the bioreactor, and the woodchips become a food source for bacteria. The bacteria convert nitrate in the water into stable nitrogen gas, a process known as denitrification. Any excess water flows up and over the bioreactor, while a dirt berm around the bioreactor diverts surface water away.
Grant Curtis, a local contractor with the Illinois Land Improvement Contractors Association (ILICA), helped with the bioreactor construction. He added that the new dam his team installed down from the bioreactor has an emergency overflow, a structure that stops trash from entering the dam and an anti-vortex feature that keeps the water from whirlpooling.
“The transformation of this area was amazing,” said Curtis. “From 2017 to 2019, I was thinking it might not work. But a great group effort made the project a reality.”
Lauren Lurkins, Illinois Farm Bureau (IFB) director of environmental policy, said the bioreactor is partly funded through the Woodchip Bioreactor Partnership. Since 2015, IFB has invested $2.4 million to nutrient loss reduction initiatives in 70 counties, including $850,000 to the Nutrient Stewardship Grant Program, that funded the field day. The funding also supports the Woodchip Bioreactor Partnership with ILICA, NRCS, and the University of Illinois. This is the fourth bioreactor installed through the alliance; two are in Henry County and one is in Bureau County.
“The goal is to install one woodchip bioreactor per year, monitoring the subsequent water quality improvements, and providing education and outreach about the practice,” said Lurkins. “We follow the science. Almost one year here, we have data to show how it works. We have come a long way and will continue to work toward nitrate reduction.”
University of Illinois ag engineering researchers are also partners in the project. Luciano Alves de Oliveira, Ph.D., helps lead the data collection and analysis at Hunt Farms.
“Water needs to be in the bioreactor for a minimum three hours for the microbes to work,” he said. “From October to May, water spent an average five hours in the bioreactor. The autosampler collected 80 samples during that time that showed a 5.6 pound-per-acre nitrate reduction and 22% efficiency, which is what we expected. During winter, nitrates were reduced 60-70% and in spring, 15-20%. We are working on designs to improve efficiency even more.”
Woodchip bioreactors can be used alone or in combination with other, edge-of-field and in-field practices. Ramirez told field day participants that bioreactors can work on a variety of sites.
“Implementing new technology is always a leap, but we have found the sweet spot for a woodchip bioreactor is 40 acres,” he said. “You need an open, grassy area and you want to minimize surface inlets to avoid crop residue getting into the structure. Farmers who install bioreactors must monitor woodchips for replacement, but they should last about 10 years. Any farmer interested can contact NRCS with questions and learn how to help cover their costs.”
Rabin Bhattarai, Ph.D., associate professor, U of I Department of Agricultural and Biological Engineering, has been working with bioreactors since 2010. Looking forward, he said the goal is to join them with other practices to reduce nitrate loss even further. He is exploring computer programs, cover crops and more as companion strategies that may supplement success.
To read more about IFB’s nutrient stewardship field days, visit www.ilfb.org/fielddays.
This story was provided by FarmWeekNow.com.