By Victoria Witke
A new University of Michigan study suggests cover crop mixtures improve farmland soil health while reducing carbon emissions better than traditional single-species cover crops.
But farmers often struggle to adopt sustainable practices like cover cropping because of costs, and advocates say they’re concerned that federal funding freezes will further hurt conservation efforts.
The study, to be published in the April issue of the journal Soil Biology and Biochemistry, researched soil collected from 10 farms with varying field conditions in Lenawee, Tuscola and Monroe counties.
Cover crops are sown between main crops to improve soil conditions. Cereal rye is the most common variety used in the state, according to the research..
The study instead grew a legume and grass mix.
Legumes partner with bacteria to supply new sources of nitrogen, which is important for plant growth, said Jennifer Blesh, one of the researchers. She is an associate professor at the University of Michigan School for Environment and Sustainability.
The crop cover mix increased nitrogen more than cereal rye alone.
“It’s like an organic fertilizer, basically,” Blesh said.
Because legumes increase nitrogen in soil, there’s less need for nitrogen fertilizers, which “have a big greenhouse gas footprint,” according to Blesh. That also reduces fertilizer costs.
The grass in the mixtures have large root systems that scavenge and cycle nutrients through the soil. It also promotes soil fungi.
“Soil fungi form really close associations with plant roots, so they can help to move carbon from plants to soil, and they can also help cycle nutrients,” she said.
“We’re in a time where more extreme weather is happening,” Blesh said. “We’ve got heavy spring rains coupled with late summer drought, so having healthier soils helps to buffer against that.”
Nate Lada is a co-owner of Green Things Farm Collective in Ann Arbor, which grows vegetables and emphasizes farming practices that build healthier soil.
Farmers in the collective use a variety of cover crops, including mixes.
Lada said keeping plants in the soil year-round stabilizes the soil, and cover crops can fill the gaps in the offseason after crops are harvested.
The farmers plant cover crops to suppress weeds, promote nutrients and create insect habitats as well as being great for pollinators, Lada said.
Despite the benefits, only about 5% of Midwest farms are cover cropping.
“If that increased to 10% of corn and soybean fields in the Midwest, that would be equivalent to removing more than one million cars from the road in terms of the amount of [carbon emissions],” Blesh, the researcher, said.
Yet, farmers often fail to implement new practices that mitigate climate change like cover crops due to scarce resources.
Farmers who begin planting cover crops take a financial risk, Blesh said.
Seeds and machinery cost money. Cover crops also take up space in a field, and laborers are needed to plant and maintain them, she said.
Cover cropping takes years to show beneficial results since it takes time to build carbon and nitrogen supplies, Blesh said.
“Because of market incentives to grow as much corn, soy or some other commodity as possible, that makes it hard for farmers to take the risk to plant anything that might interfere with that in the short term,” Blesh said.
Megan Goldenberg is the project manager for the Michigan Climate Smart Farms Project, which works with farms in Wayne, Lenawee, Washtenaw and Monroe counties to develop a climate smart farm verification program for the state.
The program supports farms practicing eco-friendly strategies.
Goldenberg said time and technical knowledge play a big role in the success of cover crops. Each field is unique and needs different nutrient management plans.
But the most degraded land – fields that require the most intense nutrient plans –are being bought by people who lack previous agricultural experience, Goldenberg said. Prime farmland is passed down, not sold on the market.
“We don’t have a very good system for incentivizing and rewarding farmers for doing the right thing, as far as environmental conservation, species protection, biodiversity and habitats goes,” she said.
“If we were better at paying farmers for their ecosystem services or better at paying them to make the transition, adoption would be higher,” Goldenberg said.
Existing state and federal programs might incentivize farmers for only three years, but it could take seven years to see benefits and not be operating at a loss, Goldenberg said.
Blesh said policies should expand to support farmers “in the transition state or who are beginning the practice” until their soil is built up to where they are seeing positive results.
Lada, of Green Things Farm Collective, said agriculture in the U.S. needs an overhaul.
“There’s been some movement, but conventional farming methods have been well understood now for 20 or 30 years, and we haven’t seen mass shifts to organic and regenerative farming practices,” Lada said.
“Farmers are like anyone else – a slow group of people to enact change, especially when they’re being pushed by industries and government subsidies towards unsustainable practices,” he said.
In 2024, the state budget provided $6 million for soil health and regenerative agriculture initiatives – methods to improve soil health, water health and biodiversity – from the Department of Agriculture and Natural Resources.
Rep. Jerry Neyer, R–Shepherd, who chairs the House Agriculture Committee, said legislators first need information from the initiatives to make policy decisions.
“At some point here, it’s got to have a payoff for the farmer to continue to use [cover crops],” Neyer said. “I’m looking forward to sitting down with the department and other groups and reviewing the successes that they’ve had, but also trying to figure out the issues.”
While soil health projects receive state funding, most program money comes from federal grant programs.
Neyer said the “red tape” farmers go through while applying for federal grants can be discouraging.
“By the time you get done filling out the applications, the season might already have started or have gone by,” Neyer said, “so it doesn’t have a benefit to an operation or to a farmer.”
He said state offices are more efficient.
Goldenberg, of the Michigan Climate Smart Farms Project, said she worries federal funding cuts by the Trump administration will further discourage farmers from adopting environmentally friendly solutions like cover cropping.
Her project is funded by the U.S. Department of Agriculture’s Partnerships for Climate Smart Commodities grants program.
It hasn’t received payments since Jan. 20.
“If that money is going away, how do we not lose that effort? How do we not disenfranchise our farmers who we have talked into taking this operational risk with the promise that we would support them for a couple of years?” Goldenberg said.
She said Michigan is one of the top states by acreage enrolled in Farmers for Soil Health, which advances soil health practices like cover crops.
The program is funded by the National Fish and Wildlife Foundation. The federal government has paused all program activity, including payments.
“That is going to hurt the social fabric of our farming communities a lot if we can’t figure out a way to damage control,” she said.
Neyer said the federal government is reviewing those programs, not necessarily stopping them. He said he isn’t as worried about a temporary hiccup.