This story was produced in partnership with NBCNews.com.

More than 20 years ago, Will Harris was a commodity cattle farmer who relied on common industrial tools like pesticides, synthetic fertilizers, and antibiotics. Today, his 2,500-acre ranch in Bluffton, Georgia, is a holistically managed, no-waste operation with 10 species of livestock rotated to graze the rolling pastures and fertilize the land without chemical inputs, resulting in rich, healthy soil.

Such regenerative agricultural practices have not only improved the land of White Oak Pastures, they also have led to the land becoming a carbon sink. By pulling carbon from the air and storing it in the ground, Harris’ ranch has been able to offset a majority of the emissions related to its beef production. A key supplier of General Mills’ EPIC Provisions brand, the ranch has become a model of how to transition to a form of farming the company says can provide a solution for addressing climate change.

“I’ve literally bet the farm on it working,” Harris told Civil Eats.

General Mills, the packaged food giant, is one of several Big Food corporations jumping on the regenerative agriculture bandwagon, escalating the buzz around the idea that capturing carbon in the soil could reverse climate change. The company took the lead when it announced this spring that it would apply regenerative agriculture to 1 million acres by 2030—about a quarter of the land from which it sources ingredients in North America.

Regenerative agriculture, a term that is often used synonymously with “carbon farming,” is a set of practices—from cover crops and no-tilling to compost application and managed grazing—that builds organic matter in the soil, effectively storing more water and drawing more carbon out of the atmosphere. Though scientists generally agree the practices, especially when used together, work to draw down more carbon, it’s not clear how much carbon can be stored that way or for how long.

The company has since rolled out a pilot project for oat farmers, as well an open-source self-assessment app available to anyone interested in implementing regenerative practices. Soil health academies and individualized coaching for farmers are in the works, as is the conversion of thousands of conventional acres into organic production.

“We’ve been looking at these farmers as the examples of what is possible in terms of soil health, diversity, and farmer resilience,” Mary Jane Melendez, General Mills’ chief sustainability and social impact officer, said. “Imagine what you could get if… more farmers were implementing these practices. It could be revolutionary.”

Danone, Kellogg, Nestlé, and a dozen other companies are not far behind. At the recent United Nations Climate Action Summit in New York City, they announced the One Planet Business for Biodiversity (OP2B) coalition to advance regenerative agriculture, rebuild biodiversity, and eliminate deforestation. And Land O’Lakes, the dairy and animal feed behemoth, is also touting its soil conservation efforts, including a new initiative to help bolster sustainability on 1.5 million acres of U.S.-grown corn.

The potential for global impact is significant. But the big question is whether the push for regenerative practices by some of the world’s biggest food companies will be effective at reversing climate change—or if it’ll just help them market and sell more products.

“It’s a good thing for companies to acknowledge that the system is damaging the climate and look for ways to reduce emissions. Where the rubber meets the road is in the specifics,” said Ben Lilliston, director of rural strategies and climate change at the Institute for Agriculture and Trade Policy (IATP). “Are they going to pay farmers more money to raise crops or animals in a different way? And if they have to make changes, or don’t meet their targets, what are the repercussions?”

‘It’s Pretty Magical’

The focus on regenerative agriculture is just the latest of a slew of climate-related strategies coming from Big Food, which also include efforts to minimize food waste, reduce greenhouse gas emissions and impacts on land by offering plant-based meat alternatives, and marketing organic or non-GMO product lines.

While some are concerned that such strategies only amount to greenwashing, Lilliston said that companies like General Mills and Danone “are well aware that climate change is real, that it’s bringing severe changes, and that it may disrupt their supply chains and production.”

About 50 percent of General Mills’ greenhouse gas emissions come from agriculture, said Melendez. So after a decade of investing in various sustainability practices, she said, the company realized there was a better approach. The “Aha! moment” came in 2015 at the U.N. Climate Change Conference, when her predecessor heard farmers talk about the impacts of a changing climate on soil health. It was “us getting religion from renaissance farmers about these practices,” she said. “What they have seen on their farms, how they’re getting economically resilient… we thought, it’s pretty magical.”

The company acquired the iconic organic brand Annie’s in 2014 and faced criticism that it was watering down the mission-driven company in its quest for growth. Then, in 2016, General Mills supported The Nature Conservancy in developing a Soil Health Roadmap, which made the case for investing in building healthier soil on U.S. croplands.

It later commissioned research on Harris’s ranch. The assessment, which has not yet been peer reviewed or published in a scientific journal, showed that the ranch offsets a majority of its emissions through carbon sequestration. Applying compost and using rotational grazing, which rotates cattle between paddocks of pasture for short periods of time, stimulates the growth of carbon-storing perennial grasses.

To expand such practices, Melendez said, the company decided to focus on its North American brands and key ingredients, including oats, wheat, corn, dairy feed, and sugar beets. It will provide farmers financial assistance to change their practices, including three years of monthly one-on-one coaching, soil sampling/testing, and the creation of custom transition plans. And while the company isn’t planning to pay premiums for regenerative practices, it’s betting that once they’re implemented, the farmers will use fewer chemical inputs, making them more profitable.

The first pilot project, which spans 50,000 acres of farmland, began this spring with a group of 45 oat farmers in North Dakota and Canada. A second pilot program, with 35 large-scale Kansas wheat farmers, will kick off in November. The training is led by Gabe Brown, a North Dakota farmer, regenerative no-till pioneer, and author of the 2018 book Dirt to Soil. Rather than prescribe a single approach to regenerative, Brown stresses that every farm is unique, and requires its own set of solutions. “I don’t want to give people recipe cards, as that’s taken people down the wrong path in the past,” Brown told AgFunder News.

In addition to boosting farmers’ incomes, reduction in the use of chemicals could help General Mills. Earlier this summer, 21 oat-based cereals and snacks, including Cheerios and many other popular General Mills products, tested positive for traces of glyphosate, the active ingredient in the herbicide Roundup. All but four of the products had glyphosate levels higher than what’s considered safe for children by the Environmental Working Group, the nonprofit that did the testing.

But it’s unclear by how much farmers in the pilot project will reduce their use of chemicals. Adopting regenerative practices will be voluntary in the General Mills’ program, and each farmer can determine how much land to devote to the project and which practices to use, said Melendez.

That, however, means farmers may set their own targets, self-report the results, and face no repercussions if the results don’t materialize, said Lilliston of IATP.

Melendez said measuring outcomes will be critical, but General Mills is still developing their own unique outcome measurements. In the oat pilot project, the company plans to use more than 50 metrics, including plant diversity, insect inventories, and water infiltration rates, as well as soil carbon testing. Farmers will also record their farm’s financial data, management practices, and the pesticides and fertilizers they use.

With 2019 as a baseline, Melendez said the company plans to follow the farmers for five to seven years. For comparison, it will evaluate control farms in the same area that are not adapting regenerative practices. General Mills is also partnering with university researchers, nonprofits, and other third parties to keep track of the farmers’ progress.

Mitigating Risks

To Harris with White Oak Pastures, the support of a large corporation in making the transition to regenerative agriculture is critical. (He became a General Mills supplier in 2014, nearly a decade after his own ranch made the transition.)

“The difficulty for any farmer trying to step out of the industrial model… is the risks they take,” said Harris. “A company like General Mills is in the position to mitigate some of the risks by guaranteeing a market for their product.”

Though in the end, it’s consumers who must decide whether they “care enough about the land, animals, community and environment” to pay more for the food produced using regenerative practices, he added.

But communicating the company’s work on regenerative agriculture to consumers isn’t always easy, Shauna Sadowski, General Mills’ Head of Sustainability, Natural & Organic Operating Unit, said recently at The Climate Underground, a conference hosted by former Vice President Al Gore. “What we’ve learned through our outreach to consumers, [is that they] don’t associate consumer product goods, like what we make, with soil. So we’re in a bit of a gap.”

And, Harris said, his profit margins have shrunk in recent years as large national and international companies have “greenwashed” competing products by portraying their practices as regenerative. “They have not really changed the way they produce the food, but they have changed the way they talk about it, so that it confuses consumers,” Harris said.

General Mills, too, has recently been accused of greenwashing. A lawsuit alleges the company misled consumers into believing dozens of Cascadian Farm food products came from a small farm in Washington state—while they’re actually sourced from large industrial farms all over the country and the world.

Science Still in Question

Some scientists remain skeptical about whether regenerative agriculture is as revolutionary as its proponents claim. For instance, Andrew McGuire, an agronomist at Washington State University, has questioned the results Gabe Brown has achieved on his farm, writing that his “extraordinary claims” haven’t been replicated enough times to prove they are “real and repeatable.” He challenged the regenerative ag community to prove that it’s not the “cold fusion of agriculture.”

At the heart of the question is uncertainty about just how long carbon can remain in the soil. The General Mills’ White Oak Pastures assessment points out that benefits of regenerative practices could actually be much smaller because the carbon sequestered could be re-emitted in the next year (or the next decade) if the ranch needs to re-integrate tillage into its practices. In addition, the study says the rate of carbon sequestration will slow in the future as soil carbon content hits a ceiling

David Montgomery, a geologist at the University of Washington and author of Dirt: The Erosion of Civilizations and Growing a Revolution: Bringing Our Soil Back to Life, said there’s no question that regenerative agriculture can sequester carbon, but the amount of carbon we can add to the soil is finite. Therefore, it’s not a panacea.

“The claims that you can reverse climate change with regenerative agriculture, that’s a real stretch. The more credible estimates are a good down payment on reducing atmospheric carbon dioxide,” he said, speaking from the Climate Underground convening. But he also stresses that the effort can easily be undone.

“If we invest in regenerative ag and 50 years later we plow it up, we undo all the benefits. We have to find a way to help maintain it there. To do that, we need policies in place to ensure that the regenerative work that’s done today is beneficial in the future.”

There’s also some disagreement about how much carbon can be captured in the first place, said Jonathan Foley, an environmental scientist and executive director of Project Drawdown. Soil carbon sequestration rates vary significantly depending on the chemical and mineral composition of the soil, the topography, land use history, soil biodiversity, and climate, Foley said.

The best estimate of potential soil sequestration published to date suggests that if we used regenerative practices on all of the world’s croplands and pastures forever—a huge assumption—we could perhaps sequester up to 322 billion tons of carbon dioxide from the atmosphere. The claim that soils could capture a trillion tons? “It just doesn’t compute,” Foley said.

He cautioned that the current buzz around regenerative agriculture is similar to “other overhyped solutions of the past,” like ethanol, algae-based biofuels, biodiesel, biochar soil amendments, and BECCS (bioenergy with carbon capture and storage). “We need to temper the initial burst of enthusiasm with a skeptical eye and an abundance of long-term data,” he said. “[Regenerative ag] is an important, but only partial, solution.”

Private or Public Policy?

Lilliston of IATP believes the company-by-company approach is less effective than stronger climate-friendly policies that apply to everyone. “The changes they are trying to make should be integrated into a broader climate strategy,” he said. “A lot of it should be publicly funded. Some of it will require new regulations. A piecemeal company-pledged approach is not going to get us where we need to get to.”

Danone, which convened 19 corporations in the OP2B coalition, said the biodiversity coalition and public announcements put pressure on other companies to deliver what they promise. “We’re private actors; we will be very transparent about what we want to transform,” said Eric Soubeiran, vice president of nature and water cycle at Danone.

The coalition plans to announce more specific plans in 2020, along with a set of indicators to measure their impacts, and will build on member companies’ existing projects, but will also include collective actions. In announcing the coalition, Danone’s chairman and CEO Emmanuel Faber called for a radical change to the agricultural system.

“The food system that we’ve built over the last century is a dead end for the future … In a nutshell, we have broken the cycle of life,” Faber said at the U.N. Climate Action Summit.

Soubeiran believes political action is indeed needed in addition to corporate pledges to reform the system, and the coalition plans to propose policy changes as well. “If we vote alone, we’re only Danone. If we have a coalition, we can create a dialogue, a forum of discussion” to help convince others in the private and public sectors, he said.

New policies that advance and reward regenerative practices would also benefit the companies themselves, said Timothy Wise, director of the Land and Food Rights Program at the Small Planet Institute and author of Eating Tomorrow. “If you’re a company wanting to do the right thing, you have a huge interest in the government making that the norm, because you’re incurring additional money and risks to change your practices,” he said. While companies may do good things to benefit their reputation or enhance their brand, in the end they’re better when the playing field is level, he added.

The problem with a company-led approach, said Wise, is that it’s likely to tackle “low-hanging fruit” and may yield results that aren’t fully environmentally friendly. “You end up with a corporate menu of climate-smart options that’s been [reduced] to those options that promote sales or that don’t threaten sales,” says Wise.

An example, he said, is companies advocating for no-till farming and cover-cropping on wide tracts of monocultures that continue to use chemicals such as Roundup. And he’s not alone in calling out those contradictions; Friends of the Earth and other environmental groups have also recently called attention to herbicide use in regenerative agriculture and several companies are piloting a Regenerative Organic label that doesn’t allow for the use of synthetic herbicides or pesticides.

It’s also the case that corporate strategies to protect the environment and prevent climate change often don’t have a great track record. For instance, a decades-long pledge by Walmart, Nike, and other global companies to avoid deforestation has been mired in problems. Loopholes for indirect beef suppliers, the fact that only some beef slaughterhouses signed onto the agreement, and a lack of government enforcement have all allowed cattle ranchers to continue to destroy the forest, despite corporate goodwill.

“What’s striking,” said Wise, “is that cleaning up the supply chain depends entirely on government enforcement. That’s not something the companies have control over. Even big buyers couldn’t move the needle on this issue.”

And the Global Roundtable on Sustainable Palm Oil, a leading certification system for the palm oil industry instituted a few years ago to combat deforestation and aid in species conservation, has done little to improve biodiversity, reduce fire hotspots, or improve wealth for villagers, a recent study found. In fact, some organizations accuse the corporations using the scheme of greenwashing, and say the program has led to violence, human rights abuses, and more forest destruction.

The bottom line, said Lilliston of IATP, is that it’s hard for multinational companies to stop hurting the environment when they want to continue growing and making more money. “There’s a tension within these companies,” he said. “The urgency isn’t quite there. From our perspective, they will have to be forced to do the right thing.”

Even if companies can work in tandem with policymakers, most experts agree that regenerative farming won’t make up for the other carbon costs associated with producing, shipping, and packaging massive quantities of food.

As geologist David Montgomery put it: “Putting more carbon in the soil will buy us some time. But if we continue to burn fossil fuels, once we fill up the soil with the carbon, all we have done is delay things a bit.”

Illustration by Doug Chayka for NBC News/Getty Images.