LEXINGTON, Ill. — A demonstration farm that focuses on
conservation-oriented agricultural practices that benefit water quality in
nearby streams has taken its research another step forward.
Research at the Franklin Demonstration Farm over the past
seven years has found that wetlands significantly reduce the amount of nitrate
and phosphorous runoff into the Mackinaw River Watershed. New studies are
focusing on the affects of cover crops to further reduce nutrient loss.
“We’re trying to determine how effective these wetlands are
in reducing nitrogen and phosphorous, but also what size do they need to be to
have that kind of effectiveness,” Krista Kirkham, Nature Conservancy assistant
aquatic ecologist, said during a recent tour of cover crop sites in McLean
“We started to build in this research by adding a cover
crop,” she said.
This marks the third year of the cover crop research. The
plots are located on the farm’s east side and a wetland system on the west side
to compare the effectiveness of both systems in reducing nutrient loss in
Various methods of applications and the type of crops are
both examined in the corn-soybean rotation.
A cover crop mixture of cereal rye and radishes was applied
aerially this year in corn, and annual rye was planted with a drill after
soybeans the previous year.
“The tenant didn’t have to change his management practices
because he does a burndown in the spring,” Kirkham said.
“This is a big learning process for us. This is the first
time we’ve delved into cover crops and learning what to expect for the
producers. We’re planning to do this project for a number of years,” she
The research is through a partnership between the Nature
Conservancy, McLean County Natural Resources Conservation Service, University of
Illinois and Illinois State University.
The cover crop research has two primary objectives.
“The main part is we’ve been doing wetland research on this
farm for about seven years, but we wanted to incorporate the addition of cover
crops to see if they can further reduce nutrients coming into tile drainage
water, specifically in wetlands, and we think they will,” Kirkham said. “We want
to be able to monitor that, and we’re lucky we have a nice research design to be
able to do that.
“We have a side of the farm that drains into wetlands that
we put the cover crops on and the other side of the farm also drains into
wetlands with no cover crops, so we have a control and we have an
The flow and content of water entering and exiting both the
wetland and cover crop areas will be monitored to compare the effectiveness of
“The second goal is for demonstration. We want to be able to
show producers and landowners what they look like on a farm and have them be
able to come out and ask questions, and we want to be able get enough data for
not only just cover, but also more soil organic data, showing the nutrients in
the soil itself to show improvements that way,” Kirkham said.
Soil testing will be conducted every other year through a
partnership with ISU’s Agriculture Department.
Research at the site has shown the benefits of a wetlands
“Over the seven years, we’ve found these wetlands can reduce
nitrate concentration anyway from 19 (percent) to about 47 percent, and
phosphorous concentrations are reduced 45 (percent) to 55 percent,” Kirkham
“That’s not really considering the cover crop aspect yet.
That’s pretty strong to be able to take to producers. Of course, the bigger the
wetland, the more you’re going to see.
“We’re seeing some very significant reductions with the
wetlands, and we’re hoping that with the addition of cover crops we’ll see even
less nitrates and phosphorous coming through.”