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Strips of native plants on as little as 10% of farmland can reduce soil erosion by up to 95%
Between two corn fields in central Iowa, Lee Tesdell walks through a corridor of native prairie grasses and wildflowers. Crickets trill as dickcissels, small brown birds with yellow chests, pop out of the dewy ground cover.
“There’s a lot of life out here, and it’s one of the reasons I like it, especially in these late summer days,” Tesdell said.
This is a prairie strip. Ranging from 10-40 metres (30120ft) in width, these bands of native perennials are placed strategically in a row-crop field, often in areas with low yields and high runoff. Tesdell has three on his farm.
He points out several native plants – big bluestem, wild quinine, milkweed, common evening primrose – that came from a 70-species seed mix he planted here six years ago. These prairie plants help improve the soil while also protecting his more fertile fields from bursts of heavy rain and severe storms, which are becoming more frequent.
“To a conventional farmer, this looks like a weed patch with a few pretty flowers in it, and I admit it looks odd in the corn and soy landscape in central Iowa. But I do it for several reasons, that I think are good reasons,” he said. “I’m trying to be more climate-change resilient on my farm.”
Research shows that converting as little as 10% of a corn or soya bean field into a prairie strip can reduce soil erosion by 95%. Prairie strips also help reduce nutrient pollution, store excess carbon underground and provide critical habitat for pollinators and grassland birds. Thanks to federal funding through the USDA’s conservation reserve programme,they’ve taken off in recent years.
But the idea started two decades ago with Iowa State University researchers and Neal Smith National Wildlife Refuge managers. Lisa Schulte Moore, a landscape ecologist and co-director of the Bioeconomy Institute at Iowa State University, who was integral to the research, knows that large patches of restored and reconstructed prairie are vital, especially for wildlife, but she argues that integrating small amounts of native habitat back into the two dominant ecosystems – corn and soya beans – can make a big difference.
“I dream of driving across Iowa [in] winter and seeing various shades of greens and yellows and oranges, rather than brown,” said Schulte Moore.
In north-central Missouri, farmer Doug Doughty has been adding and expanding conservation practices, like no-till, for decades. He also has a few hundred acres of prairie enrolled in the USDA’s conservation reserve programme. This past winter, he added prairie strips, as part of a plan to tackle nutrient pollution. High levels of nitrates and phosphorus can wreak havoc on aquatic habitats and the economies that depend on them. There are also health risks for people. Nitrates in drinking water have been associated with methaemoglobinaemia or “blue baby syndrome”, and cancer.
“Nutrients are valuable and they’re also a liability once they get out of our fields and get into streams and rivers and water supplies,” Doughty said, “and taxpayers are having to pay extra now on their water bills in locations to clean up those nitrates and phosphates.”
During an outreach event in the Iowa Great Lakes region, Matt Helmers uses a rainfall simulator to demonstrate runoff and erosion with different conservation practices. He’s one of the prairie strips researchers and director of the Iowa Nutrient Research Center at Iowa State University.
“Prairie strips can be very effective for not only reducing surface runoff, but treating water that interacts with the root zone below the prairie strip,” Helmers said.
During a big rain storm, each prairie strip in a field acts like a “mini speed-bump,” said Helmers. A thick wall of stems and leaves slows down surface water, which reduces soil erosion and gives the ground more time to soak up water. Below ground, long roots anchor layers of soil while absorbing excess water, along with nitrates and phosphorus.
Farmer Eric Hoien says he first heard about the conservation practice a decade ago, right around the time he was becoming more concerned about water issues in Iowa. But the final push to add 24 acres of prairie strips came from something Hoien saw in an plane above the Gulf of Mexico.
“I looked down and for what was probably 20 minutes, it was just like the biggest brown mud puddle I’d ever seen. And so I knew that, that stuff they say about the dead zone, from 30,000ft, was real,” Hoien said. “I know where I live, and I know that the water that comes out of our lakes eventually finds its way down there through all the river systems.”
Hoien says prairie strips offer other benefits close to home. Neighbours often tell him they appreciate the wildflowers and hearing the “cackle” of pheasants. He also enjoys hunting in the prairie strips and spotting insects he’s never seen before.
The strips are hugely beneficial for pollinator populations, which have been dropping around the world. Researchers point to a combination of habitat loss, pesticide exposure, parasites and diseases, along with warmer temperatures and more severe weather events due to climate change.
“If we can help them have a place to live and something to eat, they can be better equipped to cope with those kinds of stress that they’re inevitably going to encounter in their environments,” says Amy Toth, who is also part of the prairie strips research team and an entomology professor at Iowa State University. Research shows both the diversity of pollinator species and overall numbers are higher in prairie strips compared to field edges without native plants.
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And strips of native plants aren’t just good for pollinators. Researchers, including Schulte Moore, found a nearly threefold higher density of grassland birds on fields with prairie strips. She says that grassland birds have declined more than any other avian group in North America since 1970.
“Nationally and globally, grassland biodiversity is on very steep decline, and we need to figure out how we can share our world better with all the other species that call it home as well,” she said. We know from our data that prairie strips can help with that.”
Schulte Moore says a group of forward-thinking, innovative farmers and partnerships with non-profits, foundations, universities and agencies in the midwest have helped prairie strips gain traction, but then a
“monumental shift” happened with the 2018 Farm Act, when prairie strips became an official practice in the federal conservation reserve programme. Along with technical assistance, enrolled landowners get a 50% cost-share to install prairie strips, an incentive payment and annual payments for each acre taken out of production.
And many conservation organisations, some state agencies and even private companies are now also trying to incentivise the use of prairie strips.
“Voluntary conservation has its limits, as we can see on the landscape right now,” said Omar de Kok-Mercado, the midwest lead for land and business planning at the Colorado-based non-profit Mad Agriculture, which helps farmers with financing, market connections and community building as they transition from conventional to regenerative, organic agriculture. It recently launched a three-year pilot programme with Whole Foods Market and four farms across Minnesota, Wisconsin and Montana.
Schulte Moore and other researchers are also trying to develop new markets and economic incentives for prairie strips. This includes Grass2Gas, a federally funded, multi-institutional project investigating the feasibility of using prairie strip cuttings to produce renewable natural gas with anaerobic digestion.
Many natural resource experts and ecologists, including Schulte Moore, say prairie strips are not a magic bullet for today’s soil, water and biodiversity challenges. And they emphasise that we still need to reconstruct large prairie patches while protecting the rare remnants of original, unploughed prairie.
In Missouri, Iowa and Illinois, less than 1% of this ancient ecosystem remains. But years of research show that prairie strips can unlock some of these benefits.
“We know that we need clean water. We need to do a better job of keeping our soil in place in our fields where it can grow our crops. We know that we need to expand the home of Iowa’s native biodiversity,” said Schulte Moore. “Maybe prairie strips can be part of that solution.”
This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the midwest. It reports on food systems, agriculture and rural issues
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