Tackling the 'big brown spot': Keeping fields in living cover could be path to reducing nitrate

A portrait of a man in a field
Farmer Paul Novotny stands in a field near Chatfield. Novotny has grown both Kernza and winter camelina to help reduce nitrogen loss and soil erosion.
Courtesy of Dodd Demas for Friends of the Mississippi River | 2021

Paul Novotny grows mostly corn and soybeans on his farm in Chatfield, about 20 miles southeast of Rochester. 

But in the fall of 2016, Novotny planted a perennial grain called Kernza on about 25 acres as part of a research study.

Kernza’s deep roots — extending 10 feet or more — help absorb excess nitrogen in the soil, preventing it from running into streams and lakes or leaching into the groundwater.

Novotny continues to plant Kernza off and on. The past couple of years, he’s also tried planting winter camelina, used as a healthy cooking oil or to produce aviation fuel.

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“Somebody’s got to help figure it out. You’ve got to try new things,” Novotny said. “I think there’s other ways to grow certain things on certain pieces of land that I farm that would be better used in a different manner than you do in corn or soybeans. The only way to find out if it's viable and if you can cash-flow it is to try it, so that's what I try to do.”

A close-up of grass
Kernza grows in a plot near Edgerton is pictured on July 27.
Courtesy of Dodd Demas for Friends of the Mississippi River

As a Chatfield City Council member, Novotny knows the importance of cleaning drinking water. Chatfield’s water is safe to drink, but other cities in Minnesota have had to dig new wells or treat their water due to high nitrate levels.

Novotny thinks continuous living cover crops such as Kernza could be one way to help prevent nitrate contamination — if farmers and researchers figure out which crops and practices benefit water, the soil and farmers’ bottom line.

“It’s definitely one avenue that has some potential,” he said. “Nothing’s proven that this is going to fix it. We don’t have a solution. But can it help? One hundred percent.”

Commercial fertilizer and manure applied to crop farms is a major source of nitrate contamination in Minnesota. That’s especially true in parts of the state with sensitive geology that allows water and contaminants to move quickly from the surface to the groundwater.

Last month, the U.S. Environmental Protection Agency told state agencies they need to take action to address nitrate in southeast Minnesota's karst region to protect public health.

One potential remedy is planting crops outside of the traditional summer growing season that protect the soil with living cover.

A man stands in a field of tall grass
Farmer Paul Novotny stands in a field near Chatfield. Novotny has grown both Kernza and winter camelina to help reduce nitrogen loss and soil erosion.
Courtesy of Dodd Demas for Friends of the Mississippi River | 2021

Decades ago, Minnesota’s farmers planted a diverse mix of crops throughout the year, said Trevor Russell, water program director for the nonprofit advocacy group Friends of the Mississippi River. 

But more recently, agricultural markets have pushed many farmers into growing summer annual crops such as corn and soybeans, Russell said. They’re harvested every fall, leaving bare soil that's prone to erosion and losing nutrients.

“There’s millions and millions of acres of cropland in Minnesota every year that are left brown and barren and exposed to the elements for seven or eight months or more each and every year, year after year,” Russell said.

The University of Minnesota launched the Forever Green Initiative more than 30 years ago to develop new crops that grow year-round, to protect the water and soil and provide farmers with new economic opportunities.

“We’re developing crops that cover the soil and provide cover all year-round, and they can be harvested,” said Mitch Hunter, the program’s associate director. “Because we think that’s really important to long-term sustained broad farmer adoption.”

Two flags stand in a field of tall grasses
A Kernza plot near Edgerton is pictured on July 27.
Courtesy of Dodd Demas for Friends of the Mississippi River

That includes perennials such as Kernza that come back year after year, and winter crops like pennycress or camelina, that are planted in the fall and harvested in the spring. 

“Right now, traditional cover crops are on a few percent of the cropland acres in Minnesota and we would love to see those grow,” Hunter said. “But we think that we’ll have much broader uptake, much faster uptake, if farmers are able to protect their soil and get an economic return.”

There’s evidence to suggest that planting continuous living cover crops could have a fairly large impact on Minnesota’s nitrate problem, while also providing benefits for farmers.

A new report from Forever Green and Friends of the Mississippi analyzed the environmental and economics impacts of planting continuous living cover crops compared to the “big brown spot,” as it calls cropland left barren and unprotected.

It found that if adopted on a medium-range number of acres across the state, they have the potential to reduce nitrogen loss by more than 20 percent, soil erosion by 35 percent and increase farmers’ net profits by about 20 percent by 2050.

“We would really be able to measure the impact of these cropping systems on the landscape, in farmers’ pocketbooks and in our water quality,” Russell said.

There’s keen interest among researchers to find ways to reduce nitrate contamination that threatens drinking water supplies, where it’s difficult and costly to remove. Drinking water with high levels of nitrate can lead to health problems, including a sometimes-fatal condition in infants called blue baby syndrome.

A field of tall grass
A Kernza plot near Edgerton is pictured on July 27.
Courtesy of Dodd Demas for Friends of the Mississippi River

Forever Green is working with some cities to plant Kernza in areas from which the community’s drinking water is drawn. 

The city of Edgerton in Pipestone County contracted with a local landowner to rent land around the city’s well to grow Kernza. It's hard to draw conclusions from one project, but the results look promising, Hunter said.

“There’s actually local data from those from those areas showing a decline in the nitrates in their water system,” he said.

There are challenges to getting more farmers to plant cover crops. Markets for some, such as Kernza, are still developing. And adding a new crop means additional cost — and risk — for farmers.

“We have to be realistic that these are not silver bullets. These are not going to make everybody rich and change things overnight,” Hunter said. “There’s more work to be done to really make the systems work well in a robust way.” 

Forever Green helps farmers by providing financial and technical assistance. It also can bring on a commercial partner to buy the crop, so farmers know what they will get paid, Hunter said.

The program received $6 million from the state’s Clean Water Fund last session, as well as $1.6 million over two years from the state’s agriculture budget — the first time it’s been included.

Novotny said money spent on programs such as Forever Green is a small price to pay compared to the high cost of removing nitrate from drinking water once it’s contaminated.

“It’s a small amount of funding that's doing a lot of good work,” he said.