Mitchell Hora walks to a field on his family’s southeast Iowa farm, where 5-inch-high soybeans grow in alternating rows with 4-foot-tall cereal rye.

The 25-year-old admits that combining the two crops would make most farmers freak out.

“We’re harvesting rye with soybeans on the same acre,” Hora says. “We take a yield hit with both crops,” damaging some soybeans when the cereal rye is harvested in July. “But the combination of the two really pumps up soil health and really pumps up carbon sequestration.”

Hora and his father, Brian, hope the test will boost the farm’s bottom line, helping them earn more from emerging markets that pay farmers who adopt practices that store carbon, a major component of the greenhouse gases leading to global warming.

The basic process of carbon capture is straightforward: Plants suck carbon from the atmosphere for food. When the crops die, the carbon is trapped in the soil, blocked from contact with the atmosphere, where it would combine with oxygen to create carbon dioxide, one of the greenhouse gases that warm the Earth.

Trials like the Horas’ show practices like planting cover crops such as rye along with staples such as soybeans build soil health, help suppress weeds, hold nutrients for plants instead of allowing them to wash into streams, and prevent erosion.

Carbon farming isn’t “a huge money maker” now, Mitchell Hora says, but farmers are struggling with low corn and soybean prices, and it could be enough to push them closer to profitability.

It’s among a growing number of initiatives springing up in Iowa and the nation that pay farmers for practices that can help save the planet, while leaving growers with better soil and more sustainable operations.

Former U.S. Agriculture Secretary Tom Vilsack sees “tremendous opportunity” around improved sustainability, especially for Iowa, given the vast scale of farming in the state, agriculture’s role in environmental challenges, and the difficulties growers face in making money with traditional farming techniques.

Sequestering carbon can boost soil health, crop yields and revenue, while it improves the health of local rivers, streams and lakes and adds wildlife habitat, experts say.

It’s part of building “climate smart” farming systems that hold the potential to transform rural economies, said Vilsack, Iowa’s former governor and CEO of the U.S. Dairy Export Council. Such systems would spark new technology that adds value to crops and produces agricultural byproducts that can be used to produce electricity, chemicals and other products that now come from oil, he said.

The work can “create a series of new commodities for agriculture, and for Iowa,” said Vilsack, who’s part of a group working with the U.S. Farmers & Ranchers Alliance on developing those opportunities.

Building farm sustainability is a message that’s been preached before in Iowa, where environmental discussions have been contentious. Residents have fought over odor from large hog confinements and over fertilizer runoff into state waterways that are sources of drinking water.

The politics around climate change have made it difficult for farmers to play a role in the discussions, said Matthew Russell, executive director of Iowa Interfaith Power & Light, a nonprofit group that seeks a religious response to climate change.

Activists on the left want farmers to apologize “for wrecking the world,” Russell said, and conservatives want growers to “carry the water” on climate skepticism.

But national concern about climate change brings dollars, expertise and urgency that could shift the discussion and bring more farmers into the effort.

Farmers understand the science behind conservation practices that make their land more resilient with extreme weather, Russell said. After all, they’re among those most affected by changes.

“We might be part of the problem, but we’re also a big part of the solution,” he said.

Hora sidesteps talking about climate change, leaning on the adage that farming needs to be sustainable economically as well as environmentally. “If the farm goes out of business, none of this matters,” he said.

Cash for carbon

Corporate giants like General Mills, Cargill and Mars are setting aggressive sustainability goals and are willing to pay farmers to help meet them by growing crops and raising livestock with less water, chemicals and greenhouse gas emissions.

Startups Indigo Agriculture, Nori and the Iowa Soybean Association’s Soil and Water Outcomes Fund are among the groups setting up carbon and water quality markets to provide the financial links between farmers and businesses. Farmers can volunteer to participate and get paid for the positive outcomes they provide.

“Companies are very concerned about climate change,” said Debbie Reed, executive director of the Ecosystem Services Market Consortium, another emerging carbon and water quality market.

That’s partly because they want to take steps to safeguard their future profitability, Reed said, but also because their customers want to know “who’s producing their food and what their environmental and climate footprint is.”

Nationwide, farming generates about 11% of the greenhouse emissions — carbon, methane and nitrous oxide — that contribute to climate change as lands are tilled, trees are cleared, and crop diversity and small livestock operations dwindle.

But it’s farming’s role in absorbing greenhouse gases, not just in generating less of them, that is key to achieving climate and sustainability goals, Reed said.

“That’s the big thing that came out of the Paris (Climate) Accord in 2015, and scientists are aligned on it: We cannot possibly meet our goals by just continuing to reduce emissions,” she said.

“We need to increase the uptake of carbon from the atmosphere,” Reed said. “We know that soil is the world’s largest sink” where carbon is stored. “It’s also the one that’s lost the most carbon. We can put that carbon back. Not all of it, but a lot.”

U.S. farmers and ranchers could sequester as much as 300 million metric tons of carbon each year, which would equal about 15% of the country’s total emissions annually, said Rattan Lal, a soil scientist at Ohio State University and leading expert on carbon-capture farming. He was named this year’s laureate Thursday by the Des Moines-based World Food Prize.

“That’s a lot of potential,” Lal said, adding that it would be “a good start” in moving the the country closer to its United Nations climate change and zero-hunger goals.

Capturing 1 trillion tons

Indigo Agriculture, which has raised about $850 million, has set a goal of capturing 1 trillion tons of carbon, or a terraton, across 3.6 billion acres of farmland globally.

Jon Hennek, an Indigo vice president, said the terraton target is a long-term aspirational goal that’s grabbed attention. “It helps us understand what’s possible,” he said.

So far, the Boston startup has enrolled about 7.5 million acres in its programs, with about 500,000 coming from Iowa farmers.

“We’re focused on building the technology and data and infrastructure required to lead us to those goals,” Hennek said.

Indigo guarantees farmers in the carbon program will earn at least $10 for every ton of carbon equivalent sequestered this year, with the potential for making more, he said.

How much farmers earn depends on the conservation practices they use and the outcomes, Hennek said.

The company believes farmers can sequester half a ton to 1 ton of carbon per acre. “The potential is significantly higher at 2 to 3 tons per acre,” he said.

Tillage releases carbon from the soil, so Iowa farmers are reducing that, Hennek said. They’re growing cover crops that help capture more carbon through photosynthesis and are adding livestock to build soil fertility. They’re also working alfalfa, oats or other cover crops into corn-and-soybean rotations, and are cutting the use of synthetic, oil-based fertilizer, a large source of nitrous oxide, he said.

Mitchell Hora has some of his family’s 700 acres enrolled with both Indigo Ag and Nori, another carbon market that’s based in Seattle. The Iowa State University grad wants the experience so he can help other farmers through his soil health consulting business, Continuum Ag.

He said he thinks his family can generate $12 to $18 per acre in revenue with their conservation practices.

Hora and his dad already “plant green,” drilling corn seed between rows of growing winter wheat and soybeans into cereal rye cover crops. Typically, farmers kill the cover crops a couple of weeks before planting other crops, often before they have had much time to grow, limiting how much carbon the plants can absorb.

And the men are experimenting with “relay crops,” tweaking their 10-acre test of soybeans planted together with cereal rye. On another farm, they are planting corn in two narrow rows, then leaving a large gap where they’ll soon plant next year’s winter wheat cover crop. By doing so, they think they can more easily harvest the cover crop without damaging the corn.

Hora said his father has been decreasing tillage since the late 1980s, and they now are practicing no-till agriculture on all the family’s land. Combined with cover crops, they have cut their fertilizer use by half, and herbicide applications by 25%.

Brian Hora, 57, likes what he sees in his fields. The soil better absorbs large rains, and the cover crops help keep the valuable dirt from eroding. As the father and son talk, they dig up chunks of soil riddled with wormholes, showing where the crawlers have chewed through decaying plants that bacteria and fungi break down into nutrients plants can use.

“The last couple of days, you dig up a shovelful, and there are worms everywhere,” Mitchell Hora said. “It’s just amazing.”

Tallying ‘environmental yields’

Part of the challenge around paying farmers to store carbon in their soil lies in how to measure its effectiveness.

The companies and groups creating markets will use satellite imagery and modeling, along with on-the-ground testing, to evaluate the environmental benefits.

Adam Kiel, the Iowa Soybean Association’s director of conservation, said his group will test 10% of acres annually, while national carbon startups are looking at sampling 1%-5%. The group also is taking water samples throughout the growing year.

“We’re stacking these outcomes together, looking at carbon and water together, and finding two buyers” for the credits, Kiel said, potentially generating $30 to $50 an acre for farmers.

Kiel hopes that farmers begin thinking about “environmental yields” along with the corn and soybean production. “We want farmers to know the changes on their farm can provide a benefit,” he said.

Farmers are responding. The Soil and Water Outcomes Fund plans to enroll 100,000 acres next year, more than 10 times the acreage that is now part of the trial. The water quality work is currently targeted in the Ames and Cedar Rapids watersheds.

Emily Heaton, a biomass crop specialist at Iowa State University, said practices such as adding cover crops to corn and soybeans are a step in the right direction.

Heaton, who’s working to quantify the greenhouse gases that various crops release and sequester, hopes that farmers look to practices that accelerate carbon capture in soils, such as restoring pastures and prairies with deep-rooted perennials.

Or they could convert some corn and soybean acres to growing Miscanthus, a perennial grass that’s part of the biomass the University of Iowa uses to fuel its power plant. The university is beefing up its purchase of Miscanthus, oat hulls and other biomass to help cut its coal and natural gas usage.

“Change happens slowly,” Heaton said, “but we’re in a bit of a rush,” given the climate change threat.

“If you have to fit in a prom dress in two months, you’d better do more than switch to Diet Coke when you order that super-sized fast-food meal,” Heaton said.

Overcoming tradition

The biggest financial benefits farmers will see from the conservation practices tied to carbon farming come from changes in their soil, says Jerry Hatfield, who led the National Laboratory for Agriculture and the Environment in Ames until retiring in January.

He said a northeast Iowa farmer doubled the organic matter in his soil, a measurement of carbon sequestration, by significantly reducing tillage and growing cover crops, adding $75 to $100 per acrein revenue with improved yields. “That’s the real value of carbon,” Hatfield said.

Possibly more important, he said, is that the work decreased the impact of intense rainfall in the spring and too little precipitation in the summer. Better soil health improves water infiltration and holds water when it’s needed in dry months.

It also decreases flooding, which has plagued the state in recent years. Damage from flooding along the Missouri and Mississippi rivers last year hit an estimated $2 billion in Iowa.

Hatfield estimates that Iowa could reduce its carbon footprint by 25 million tons of carbon annually, with farmers growing cover crops and parking the tractor during spring and fall tillage. The impact on water alone would be tremendous, he said.

Despite the benefits, tradition drives practices for farmers, Hatfield said. Carbon-capture farming “sounds kind of radical ... and there’s economic risk to all of this,” he said. Farmers can lose yields and money, for example, if they use a cover crop that ties up nutrients when cash crops need them.

And few markets exist for a third crop, such as oats, that can be added to a corn and soybean rotation to improve soil health and carbon retention.

Hatfield said the average age of Iowa and U.S. farmers — both 57 — also may make growers less receptive to change.

“You get to a certain age where you’re comfortable and you don’t want to do something different,” Hatfield said. “We’re all that way.”

But Wade Dooley, who farms with his father near Albion in central Iowa, said his generation is looking for change, primarily because of the difficulty in making money by farming.

That’s why the 37-year-old said he’s willing to try new practices and share his experience with other growers who worry adding conservation practices that build carbon will backfire.

“When you try something new, you’re more likely to screw up,” Dooley said. “And when times are tough, nobody wants to make those mistakes.”

Dooley, who’s waiting to see which carbon market program works best before joining, said adopting conservation practices is a “ladder, not a diving board.”

“It’s going to take us all putting our bits and pieces together to do dramatic things,” he said, adding that farmers have the ability. “We converted almost the entire state from tallgrass prairie to corn and soybeans. ... We can shift the biology again.”

“The climate is changing, and we’ll have to change with it or we won’t have a job,” Dooley said.