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Testing the water

Team of scientists formed the Judith River Watershed Nitrogen Project to solve high nitrate concentration in local groundwater
Posted at 10:23 AM, Jun 06, 2021
and last updated 2021-06-06 12:23:41-04

In the middle of Montana, folded among the gentle island ranges of the Little Belt, Big Snowy, Judith, Moccasin and Highwood mountains, a blanket of working lands stretches to the horizon. With the Upper Missouri River Breaks just a stone’s throw away, the scenic backdrops of Judith Basin and Fergus counties are Charles M. Russell paintings brought to life, where Montana’s postcard beauty is on full display, where wide open spaces linger beneath a blue big sky.

(Cover photo: MSU researcher and Extension specialist Adam Sigler checks a data logger that has been recording groundwater levels in an abandoned well near a historic granary. Shallow hand-dug wells like this are common in the area where groundwater is only 20 feet below the surface, and many of these wells are still in use.)

Agriculture has driven the local economy of small central Montana communities for at least 120 years. Within the two counties’ 6,400 square miles, there are more than 200,000 acres of wheat planted each year and fewer than 14,000 people. Beneath the grain fields, hay grounds and cattle pastures, underground rivers run like veins and arteries, supplying drinking water to hundreds of residents and recharging nearby rivers and streams. But historically, groundwater in the shallow aquifers of this area has contained a high level of nitrate, a form of nitrogen, which can pose health risks to the community and indicates nitrogen loss from the soils where it is needed, potentially threatening the long-term viability of the area.

In 2011, researchers from Montana State University, including MSU Extension, and Utah State University partnered with the community to identify the causes of the high nitrate concentration and try out agricultural practices that might reverse the problem. A four-year study that has led to ongoing research in the area, the Judith River Watershed Nitrogen Project, was funded by a grant from the USDA National Institute of Food and Agriculture and brought the university’s land-grant mission to life using applied science to serve the needs of a rural Montana community.

“Extension integrates teaching, learning and engagement,” said Cody Stone, executive director of MSU Extension. As the executive director, Stone oversees numerous Extension projects across the state. “We’re really focused on strengthening social, economic and environmental viability for communities in Montana. The Judith River Watershed Nitrogen Project is a really excellent example of the ways in which Extension is working across the state in communities and in the lives of people in Montana.”

Above the threshold

When W. Adam Sigler joined MSU Extension 16 years ago, his predecessor, water quality specialist Jim Bauder, had a robust dataset from well testing, but it was from the 1980s. So, in 2005, Sigler launched a new well testing program.

“Central Montana had always come up with the highest levels of groundwater nitrate in the state,” Sigler said, adding that levels were higher than the federally recognized drinking water threshold of 10 milligrams of nitrogen per liter. Drinking water above that nitrate concentration can put babies and infants at risk of developing methemoglobinemia, or blue baby syndrome — a condition where a baby’s skin turns blue because the blood is unable to carry a normal amount of oxygen through the body.

Sigler added that some research has also found a correlation between exposure to high nitrate levels and an increased risk of cancer in adults, and the downstream effects of nitrates can lead to algae growth once groundwater makes it to the surface in rivers and streams, which can disrupt ecosystem health.

High nitrate concentrations also have economic implications for crop growers, who are concerned with soil health and productivity. Nitrogen fertilizer is commonly applied to crops, such as wheat, to maximize profit. But with up to 12 million pounds of nitrogen in groundwater per 100 square miles in the area — well below the soil and inaccessible to crops — some started to question what the opportunities were for increasing the efficiency of nitrogen use.

Sigler said it might be logical to conclude that high groundwater nitrate is the result of nitrogen fertilizer application, but in a place like the Judith, where high levels have likely been occurring since before fertilizer was a common practice, “the story is a lot more nuanced than that.”

Uncertain of the cause of the high nitrates, let alone how to resolve them, Sigler partnered with an interdisciplinary team of scientists in 2011 and undertook the research as the focus of his doctoral degree, completed in 2020.

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MSU researcher and Extension specialist Clain Jones examines pea crops at the MSU Post Farm in Bozeman. The researchers found that crop rotation — replacing fallow with pea crops — was a solution to the nitrate leaching in the Judith Basin.

Stephanie Ewing, associate professor of soil science in MSU’s Department of Land Resources and Environmental Sciences, served as lead investigator on the USDA grant and graduate adviser to Sigler. She said it was a true team effort that required involvement from the community, and each member of the research group lent valuable insight from the perspectives of soil health, water quality and the social sciences. Joining Sigler and Ewing were MSU soil fertility Extension specialist Clain Jones, rural sociologist Doug Jackson-Smith, formerly of USU and now at Ohio State University, and the local producers and stakeholders themselves.

“It required a patient conversation to really appreciate each other’s perspectives,” Ewing said, adding that the research team genuinely got to know area producers and sought to integrate their knowledge and experiences. “We were talking to people who are the third or fourth generation to work this landscape. We looked at how their relationship with the land could inform what we were doing. It was about figuring out the picture together of what’s going on, and what we, as a community, (were) going to do about it.”

The crux

After surveying some 275 farmers and gathering 14 area stakeholders to form a research advisory committee, the scientists began to survey the land and collect data. Obtaining samples from beneath a growing crop proved to be a formidable challenge, as producers seeded and harvested around moisture sensors and lysimeters that were installed in their fields. The scientists had to install their instruments in pits in the fields and cover them when farmers planned to operate machinery.

Based on the area landform and rock properties, the research team concluded the nitrate levels weren’t naturally occurring from bedrock, meaning that the only way for nitrogen to end up in the groundwater had to be through the soil. Interestingly, though, Ewing said that in addition to the suspected nitrogen fertilizer, soil organic matter — the dark part of soil that provides much of the nutrients and health of a soil originated from plant material — turned out to be a major contributor to the nitrate concentration. As the leftover plant parts break down in the ground, microbes contribute to the decomposition, converting nitrogen that’s unavailable in organic matter into nitrate, which plants can use. Nitrogen is an important element of soil health and contributes to crop yield and grain protein. However, heavy rainfall can leach the nitrate from the soil into the groundwater.

“That’s really where the crux is,” Ewing said. “It’s not just about what you put on crops this year, but it’s also about the sequence of crops that you plant and how you manage them.”

Throughout their research, the scientists called upon six area producers and the 14-member advisory committee to determine what research questions were applicable and what agricultural strategies should be tested to see if they limit the nitrate loss to leaching from the soil. They held regular meetings, hosted field days to engage the broader community, knocked on the doors of dozens of landowners, worked with local radio stations and newspapers, and held public presentations where the farmers presented the research.

“I feel like we were learning alongside the producers,” Sigler says. “We came to the meetings with data and ideas but not always with the answers.”

The scientists presented nine management practices that could be field tested for their effects on nitrogen, and the producer and stakeholder advisory committees opted to test three: replacing fallow rotations with a pea crop; testing slow-release nitrogen fertilizer; and splitting nitrogen applications over time rather than applying all at once. These practices were tested between 2011 and 2015, and only one limited nitrate leaching levels: planting peas.

“Replacing fallow with peas came out as the winner, and we think that’s partly because peas leave the soil somewhat drier than fallow going into the next year,” Jones said. “Peas are also very good nitrate scavengers, so before they start fixing their own nitrogen, they take it up from the soil. So, where peas were planted, they were able to decrease both water and nitrate levels in the soil, lowering the amount of nitrate moving to groundwater.”

A path forward

Katie Hatlelid, the Judith Basin County Extension agent, served on the research project’s advisory committee and has continued to work with area producers on questions of soil and water health. “It’s been a pretty eye-opening project for producers in the area in just how easily nitrogen can leach into the groundwater,” she said. Hatlelid’s family farms in the area, reinforcing her personal interest in the issue. She said employing the three elements of MSU’s land-grant mission — research, education and outreach — has been an important aspect of the Judith River Watershed Nitrogen Project.

“It really reinforces the importance of our land-grant university.”

To gauge the applicability of their research, the scientists conducted surveys in 2012 and 2015 that measured whether farmers considered nitrate leaching in their overall management decisions. With the help of Jackson-Smith, the team found that by 2015, 85 percent reported that they were considering the issue and were interested in making management changes, up from 35 percent in 2012.

Jones is certain it wouldn’t have been nearly that high if it hadn’t been for the real, personal relationships the team spent years forming with the people who knew the land best.

“It was an evolution,” he said. “If we’d come in, done the research and showed them the results, there wouldn’t have been nearly the buy-in. But because we worked together through every step of the process, we had that level of trust.”

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Soil science professor Stephanie Ewing, left, and graduate student Caitlin Mitchell, right, sample water from Louse Creek near the town of Moccasin. The researchers found that creeks in the area are almost exclusively groundwater fed, and that management of both soils and stream corridors can influence nitrogen loss.

Among producers involved in the project, Nita Bronec and her husband farm near Denton, where they grow predominantly spring and winter wheat. Bronec says she was interested in the study because it addresses a social and agricultural issue that is directly linked to the future of her community. Since learning that cover crops like peas can potentially mitigate high amounts of nitrate leaching, they are implementing new farming practices and trying cover crops and continuous cropping. “We want to do our part to see if it helps,” she said. “If everybody starts doing a little bit, somewhere along the line it helps.”

While finished with the Judith River Watershed Nitrogen Project, the soil and water scientists are far from finished working with the Judith Basin community. Sigler is continuing his well education program through MSU Extension. With funding from the Montana University System’s $20 million National Science Foundation EPSCoR grant, Ewing is leading an expanded team in conducting follow-up soil, groundwater and surface water studies that continue to integrate soil health and water quality with applicable results that can improve livelihoods in Montana.

“The influence of the work is ongoing, including in some subtle ways that I think we’re not even aware of,” Sigler said. “It was a special project.” •