Greg Stoffel did everything right after struggling for years with his low, flood-prone cropland on the Vermillion River. He stuck the 56 acres in the government's Conservation Reserve Program, planted it with a native seed mix and got a permanent easement to ensure it would remain grassland forever.

The local school district owns the land now, a verdant field biology classroom for students with harriers, pheasants, deer and eagles. It is a notable conservation success.

And it's the opposite of what often happens.

Minnesota's grasslands continue to disappear to the plow, despite ongoing rescue efforts on multiple fronts. For every conservation win like Stoffel's, more grassland is plowed into corn, soybeans and other crops to meet relentless global demand for food and animal feed, and for ethanol and other biofuels. Farm support programs such as crop insurance can encourage expansion.

Minnesota lost nearly 2 million acres of grassland to crops from 2012 to 2019, according to the World Wildlife Fund's Northern Great Plains program. That's more than the state of Delaware. More is lost each year, though the rate has slowed in the past decade, said lead scientist Patrick Lendrum.

"This is an alarming trend of continued conversion of the least protected and most at-risk biome on the planet," said Lendrum. "This is happening in our backyard."

The clearing of grasslands is a key reason behind startling declines in pollinators and certain types of birds such as meadowlarks. It has also weakened the land's ability to filter and store water, threatening water and soil quality, and it feeds into climate change because grasslands can store substantial amounts of carbon.

Imperiled grasslands don't get as much as attention as tropical forests, said University of Wisconsin researcher Tyler Lark. But the destruction of the Great Plains across North America is on par with clearing the Amazon rainforest in Brazil, according to Lark and the World Wildlife Fund.

"I think land-use change is one of the largest environmental challenges — maybe No. 2 right behind climate change," Lark said.

Spreading agriculture

Lendrum's research is based on satellite imagery and other data from the U.S. Department of Agriculture (USDA), focusing on all intact grasslands that haven't been recently farmed, such as pasture or wetlands, that are then plowed. While that may include some untouched native prairie, there's very little of that left in Minnesota.

One of the hot spots in the state is the northwest. Marshall and Polk counties, for example, each saw more than 120,000 acres of grassland tilled for crops from 2012 through 2019, according to Lendrum. That's about 10% of each county's land.

The development of short-season seed varieties has enabled farmers to grow row crops where they couldn't before, pushing such agriculture farther north.

Though it is not the case everywhere, most of the newly plowed grass in the northwest is land taken out of the Conservation Reserve Program when the 10- to 15-year contracts expire.

Mark Haugen, for example, said he took about 1,600 acres of grassland out of conservation in 2019 to expand the family farm in Roseau County, near the border with Canada. He doesn't see a problem.

"There's no shortage of habitat in our county," said Haugen.

The Haugens farm 5,000 acres of soybeans, wheat and turf grasses such as bluegrass and ryegrass. To Haugen, the community gains from expansion far outweigh environmental impacts. Stronger farm incomes and land values have strengthened the local economy, he said.

"Every building downtown in Roseau has a business in it, and it didn't 10 years ago," Haugen said. "Our community is updating our school, and where does that come from? Land taxes."

Haugen said he works hard to care for the land. He tills as little as possible, plants cover crops and precisely applies necessary chemicals.

"If there's something you love, you're going to take care of it," Haugen said.

All the individual decisions and incremental expansions add up to big impacts, conservationists say. Habitat loss is a key driver of the great bird decline underway.

"Grassland birds in Minnesota are declining at frightening rates," said DNR nongame specialist Michael Worland.

In Minnesota, hard-hit species include the Leconte's sparrow, greater prairie chickens, the western meadowlark and marbled godwits. The birds are beautiful and play a role in the ecosystem, Worland said, although we often don't know the role until the bird is gone.

"They're excellent indicators of the conditions of grasslands," he said.

Clearing grasslands also reduces the ground's ability to store and filter water, a growing concern given Minnesota's generally wetter climate. Farming more marginal land can mean tilling more sloped areas, for example, increasing risks of nutrient runoff and erosion, said Lark.

Rylie Pelton, a researcher at the University of Minnesota's Institute on the Environment, said she sees a significant carbon sponge being lost.

"If we're going to be reaching our 1.5-degree [Celsius] climate mark, we need to minimize these changes," Pelton said. "Without doing that we're going to have a big problem."

Image problem

Nearly all of the waving native prairie that once covered southern and western Minnesota is gone. Only about 250,000 scattered acres remain, according to Greg Hoch, DNR prairie habitat coordinator. And Minnesota still loses an average of about 200 acres of native prairie every year.

It's difficult to rally people around grass, Hoch said. Most have never experienced a prairie stretching to the horizon. It's not part of our memories now, he said.

"People like mountains and majestic trees," Hoch said. "But grass is what you mow on Saturday afternoons."

Hoch called grassland conversion an "insanely complex" problem.

One thing is clear: Reserve program acres have been dropping in Minnesota. The key conservation tool just doesn't pay farmers enough to let land sit idle.

"It's not coming close to what they can making planting it in corn or beans," said Stoffel. "That's the problem."

The USDA recently boosted conservation payments 10% and added other incentives as it focuses on climate change.

Other efforts continue. Government easement programs abound. The Nature Conservancy, for example, has been piecing together a prairie corridor in western Minnesota. And the National Audubon Society has its "grazed on Audubon certified bird friendly land" seal for beef packages, which means farmers allow their cattle to graze freely on open grasslands, among other things. It has certified 139 livestock producers on 3.5 million acres of grassland so far, but none in Minnesota yet.

"The plight of grasslands is so linked to our food system," said Audubon spokesman Anthony Hauck.

Stoffel said he doesn't know how to solve the problem, besides paying farmers more for land conservation. All he knows is he's "happy as heck" seeing students and bird-watchers flock to his former fields, along with all the wildlife that has returned.

"I can go down there on any morning and sit down there on that road and listen to the roosters cackle," Stoffel said. "That's a big thing for me."

jennifer.bjorhus@startribune.com 612-673-4683