Farm serving as laboratory
GRANADA – To walk along Elm Creek at the edge of Darwin Roberts’ property, it would be difficult for a casual observer to notice anything unusual.
Corn grows in neat fields up to a dirt road. The opposite side of the road is wooded along the creek. The road ends at what looks like a meadow, complete with bobbing black-eyed susans and the chirping of birds.
On Thursday morning, a group of scientists, farmers, and county agency personnel met there, not to appreciate its beauty, but to talk about what lies underneath.
Roberts is known for his water conservation efforts, and this portion of his land is used by the University of Minnesota as a research station.
Water quality has always been of concern to local farmers, but the residents of the Elm Creek watershed have special reason to discuss it.
The watershed runs through Jackson, Martin and Faribault counties, and the creek is on the Minnesota Pollution Control Agency’s list of impaired waters. It is one of four watersheds in the state chosen to pilot the new Minnesota Agricultural Water Quality Certification program.
Dr. Joe Magner with the University of Minnesota acknowledged that current practices have not been enough to clean the water.
“There are water quality issues out there,” he said. “The kinds of things we have been doing in the past haven’t gotten us to where we want to be. … We need to start thinking outside the box.”
Roberts had to point out on his land where the conservation practices actually were located, and that is part of the plan.
“Our objective is to not take cropland out of production,” Magner said.
Under two feet of dirt, below the field of corn and the road, is a woodchip bioreactor. Roberts has two of them under his farm.
The bioreactors are filled with wood chips, which slow down and filter water coming off the fields. Magner said it sequesters nitrogen and holds back sediment before emptying into the creek.
Magner said Roberts’ fields use wood chips, but in areas with fallen wood, the same effect can be created. He is working in the surrounding area to create a more open system in a wooded area.
Magner recognized that there are some downsides to the systems, including the possible creation of methylmercury if poorly managed. Methylmercury is a type of mercury that can poison humans and animals.
Another conservation practice shown Thursday is a constructed wetland.
Chris Lenhart, also with the University of Minnesota, said constructing wetlands is a good way to get back the benefit of a natural resource that has been drained away in most of southern Minnesota.
Studies have shown that wetlands remove 80 percent of nitrates over time, with numbers close to 100 percent during certain times of the year. They are less effective at removing phosphorus.
He said the wetland on Roberts’ property had a rough year, being installed while the ground was still frozen, and flooded in June before the plantings were established, but they have seen some of the benefits they were hoping for, including decrease of water volume as the water slows and evaporates.
“This is the first one of its type in the area,” Lenhart said. “There haven’t been any specifically designed for nitrate removal.”
The size of the wetland depends on the size of the fields it is draining, Lenhart said, as they are connected to tiling outlets. Typically, the size is 1 percent of wetland to ag area.
Another conservation practice being studied in surrounding areas and discussed Thursday are two-stage ditches.
The ditches are a relatively simple change to existing ditches, according to Magner.
Installed in the ditch is a small floodplain area, called a bench, that gives the water room to spread out and slow down.
The ditches do take a little more space than most existing ditches, but reports in the study areas indicate farmers consider the reduction in flooding worth the small acreage lost.
It is in the combining of water-quality methods that Magner hopes to find the solution to Elm Creek’s water-quality problem.
“We don’t want just random acts of conservation,” he said. “We want a cumulative effect. … We need to recognize we aren’t necessarily going to get full treatment at each location, but there is a cumulative effect.”
Reggie Liddel, with NRCS, said many conservation programs have funding sources available, and farmers interested in water-quality projects should talk to their local offices about it.
“All these come down to managing the water coming back into the landscape,” Magner said.