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Research turns focus toward finding solutions to nitrate contaminated groundwater

Published: Jun. 30, 2021 at 9:01 PM CDT
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PLOVER, Wis. (WSAW) - As research continues to analyze the full scope and impact of the problem of nitrate-contaminated groundwater in the central sands region of Wisconsin, newer research is turning toward finding solutions to the problem.

Kevin Masarik has been working with communities impacted by nitrate contamination over the last five years to understand the problem and its source. He is a groundwater education specialist with UW-Stevens Point and UW-Madison Extension. The impacted region is in portions of Portage, Wood, Adams, Juneau, and Marinette counties and the research has found the largest source of the contamination is from farms, with a small source being septic systems.

At community meetings throughout the region over the years, the source of the problem was debated despite the local research, but Masarik said now, attitudes are shifting.

“I feel like they are really interested in finding ways to improve water quality. I think there’s an acceptance that this is an issue and that the only way it’s going to be addressed is if we all kind of pool our resources and our skill sets,” he said. “They are really good at growing crops and growing food. We are really good at designing experiments that can monitor and quantify the water quality benefits. So, being able to have those open conversations has really been helpful.”

Experimentation

Last year, after receiving a grant, Masarik conducted his first phase of an experiment to find ways to minimize nitrate contamination with a commercial potato crop. He chose potatoes for a few reasons; 1) it is one of the biggest crops grown in the region, 2) it has a great need for nitrogen nutrient application, and 3) it was one of the crops that leached the most nitrogen into the groundwater.

The way potato crops are planted, the plants are on high mounds with valleys of ground in between where there are no other plants or roots and where water can pool easily.

“There’s a lot of parts of the field where there’s just not root mass that’s going to be able to remove water and nutrients from the soil,” Masarik explained. “So, it’s partially the amount of fertilizer that that crop needs, but also the physics of how water moves in that system that leads to more nitrogen loss.”

To target that problem, he and his students planted grass between the potato crops to create a root mass that would soak up extra water and nutrients the potatoes did not absorb. Last year it was a mix of ryegrass and millet. This year, they changed the grass to a mix of barley oats and millet because they found the ryegrass preferred cooler conditions and could not grow fast enough to compete for sunlight between the potatoes.

“The nitrate challenge is really a challenge of that upper foot,” Masarik began. “It’s how do we ensure that we maintain the nitrate in the part of the soil profile where plants are actively able to interact and scavenge it.”

Isherwood Family Farm allows them to conduct experiments on a portion of their commercial potato farm and have access to the land whenever they need it. Masarik and his students placed 10 wells strategically around the experimental area and in the control area which they test regularly. The Isherwoods farm the fields as they would normally. Masarik made sure the monitoring equipment and wells would not interfere with the farming operation not only to work cooperatively with the farm but also so the farming practices would not be inhibited by the equipment and impact the research.

Making changes

Justin Isherwood said he has allowed his alma mater to conduct experiments on the farm since the 1970s. His motto is “science matters” and he encourages experimentation to continue to “move the needle” towards more sustainable farming. He said the experiments he has focused on have targeted water quality because of his upbringing on a dairy farm and the implementation of irrigation in central Wisconsin in the 1950s; he also lives near water. His philosophy is that his farming should allow the water to go back to the community as clean as reasonably possible.

“That’s part of agriculture; it’s conscious, if not it’s best practice,” Isherwood stated.

The experimentation and the implementation of positive results on his farm are often small and calculated, however.

“There’s a risk factor. If you try something that is a risk to the crop or a risk to the production, you’re hesitant to do that on a large scale,” he said.

Masarik is cognizant of the barriers, risks, and costs farmers will have to make to change and incorporates that into his experiments.

“We’re also really interested in knowing what impact that’s going to have on the potato crop itself because, obviously, we don’t want to recommend practices if they’re going to be overly burdensome to the farmer,” he said, adding that meaningful change will not happen if the farmers cannot get on board with the change.

They are going to monitor the crop yield along with the shape and size of the potatoes as they factor the farmers’ needs into the research. There is existing research to show cover crops and having multiple types of crops in an area versus the same crop across a field leads to more environmentally sustainable farming, however, Masarik notes the industry is not structured to support that type of farming.

“The reason our food tends to be so cheap is that the environment absorbs a lot of those costs and if we truly want to incorporate environmentally sustainable practices, it might come at an added cost,” he said adding that there are a lot of companies willing to absorb that cost or pay farmers more to implement conservation practices.

“Being able to quantify the benefits makes it more attractive for companies to feel confident that it’s worth that added cost for them to be paying farmers to do that.”

The magnitude of the problem

Masarik says this one experiment will not solve the problem of nitrogen-contaminated groundwater, though the thought is it will help farmers move in that direction once they find a viable option. Whatever method is found to work for potatoes, though, may not work well for other crops that need a lot of nitrogen, like corn.

There is also a big problem between the harvest season and the growing season since there is nothing to absorb the nitrogen on the topsoil during the winter. He said that is an area that needs more exploration, with the knowledge that cover crops during the growing season work well to take in those nutrients left behind.

Whatever mitigation system for potatoes they find, Masarik said it also will not likely be an immediate solution for the people with contaminated wells, especially if they are beyond the point where a reverse osmosis system works to filter out the nitrogen.

He said it has taken time to get farmers and others to understand the complexity and urgency of this problem that could take a long time to mend.

”The magnitude of the problem is that the drinking water standard is 10 milligrams per liter and we have some wells that are 30-40 milligrams per liter. So, the solutions-- the tools we have in our toolbox right now, 10-20% reduction does not get those wells that are at 30 or 40 below the drinking water standard,” he said.

“So, the magnitude of the challenge is that we have significant amounts of nitrate that are lost and meaningful progress means, sometimes, substantial changes to the current system or to the current status quo, and if that’s not possible, then it’s a question of how to compensate people that might be aggrieved or might have wells that are contaminated,” Masarik continued.

“So I’ve always said it’s got to be a two-pronged approach. We have to find ways to reduce nitrate loss to groundwater, but in those areas where it might take too long, you know, it might take years or decades to notice measurable improvement, and in some areas, that improvement might be too small to get people safe water, we as a state have to find ways to compensate those people to get them safe water and right now we’re not doing a good job of either of those things.”

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