(Maryland News Connection) The owner of Deep Roots Farm in rural Maryland and her workers finished the fall harvest last month, but some of their most vital plantings are still in the ground - and growing fast.

Four species of cover crops - plants such as winter rye and hairy vetch, later removed in the spring - are key to soil resuscitation efforts underway at Deep Roots, 53 acres of rolling hills that used to be part of a tobacco farm.

After purchasing the property two years ago, owner Gale Livingstone set about rebuilding the soil's health, by nurturing the microbiome beneath, planting cover crops, and doing no tilling at all.

The changes mean "you're going to have an abundance of harvest," the 49-year-old said.

Deep Roots is one of a rising number of so-called "regenerative" farms that are improving soil quality not only for its environmental and human health benefits but to trap more planet-heating emissions and curb climate change.

Changing farm practices could capture and store up to 250 million metric tons of carbon dioxide annually in the United States - or 4 percent of the nation's emissions - the National Academy of Sciences found in 2019.

Scientists, advocacy groups and newly-formed companies are working to quantify the amount of carbon farmers store in their soil, fueling offset markets where the resulting credits are sold.

Several commodities and agriculture companies have set up carbon farming programs in recent years, drawing growing interest from companies that have made net-zero pledges and are seeking to reduce their carbon footprints, in part through purchasing offsets.

The government has also lent its support. In September, the U.S. Department of Agriculture announced a first-ever round of grants focused on "climate-smart" commodity production, part of a $3 billion program aiming to boost crops' ability to store carbon.

"Suddenly everyone is hearing about soil carbon storage," said Lauren Miller, an executive vice president with Grassroots Carbon, a firm that connects businesses interested in buying soil carbon credits with regenerative farming operations.

Farmers "should be aware of this as another revenue stream – if they adopt regenerative practices, it will improve the soil health ... but they can also get paid for it," she added.

Yet many farmers - including Livingstone of Deep Roots - and climate campaigners are skeptical about the effectiveness of soil carbon markets.

Some are concerned they could help climate polluters who purchase offsets avoid cutting their own firms' emissions, or that the carbon stored in soils may not remain there permanently.

These markets "face a number of really big challenges," said Freya Chay, a program associate with Carbon Plan, a nonprofit that analyzes climate solutions.

Soil carbon levels vary widely and are very hard to measure, and standards set up to facilitate such markets have shown a "huge variation in verification rigor", she said.

And while prices for soil carbon are rising, they remain too low to widely change farmer behavior, Chay added.

University of Maryland regenerative agriculture fellow Matthew Houser likened soil carbon markets to "the Wild West".

"It's like a gold rush. People are trying to figure it out, but there's not a lot of clear structure and knowledge," he said.

'Putting carbon on the farm balance sheet'

Today there are around 100,000 regenerative farms in North America, according to Jonathan Lundgren, director of the Ecdysis Foundation, which is assessing hundreds of operations a year.

In doing the assessments, "we're trying to answer a few simple questions," he said.

That includes whether regenerative agriculture works no matter what you grow and where you grow it, and whether it genuinely cuts pollution, provides lasting carbon sequestration and helps battle climate change.

For example, he said, early findings from almond orchards in California suggest that farms that use regenerative practices have around 30 percent more soil carbon than conventional ones.

Another initiative, called the Soil Inventory Project, is seeking to develop a national map of soil health.

The efforts aim, in part, at "putting carbon on the farm balance sheet", said Kristofer Covey, its co-founder and president.

At last month's COP27 U.N. climate summit in Egypt, a group of 12 agribusiness firms, from PepsiCo and Mars to McDonald's, committed to boosting regenerative practices and raising farm includes with strategies including carbon removals.

PepsiCo last year announced it would seek to spread regenerative practices among its supply chain's farmers across at least 7 million acres globally by 2030.

"Climate change poses significant risks to farmers in our supply chain," said Rob Meyers, the company's vice president of agriculture.

Many farmers don't talk about climate change, but say things are "not normal anymore", he said, noting it was "one consistent thing we hear from them".

Giving farmers cash for storing carbon can help pay for a switch to regenerative agriculture - and help commodity companies meet their own goals, said Grassroots Carbon's Miller.

"Companies aren't just trying to reduce their carbon footprint anymore," she added.

"They're looking at going carbon-neutral, carbon-negative and working toward regenerative (agriculture)."

Still, the effect of such shifts on climate change remains unclear, said Chay of Carbon Plan.

With many contracts for storing soil carbon lasting just 20 years, for example, carbon sequestered on farmland today could be released in the future, she warned.

"If you're allowing low-quality offset credits and that's influencing (corporate) planning in the short, medium and long term, we have a real problem regarding being honest about what we're achieving," she said.

New economic structure

For now, many farmers across the United States are believed to be taking a wait-and-see attitude on soil carbon markets - especially smaller-scale producers.

An October report from the Farm Journal - a trade magazine - found that of 500 farmers surveyed, 97 percent said they would not get involved under current conditions, although nearly a third expressed interest and said they were monitoring developments.

One obstacle is the low current value of soil carbon, often around $15 to $20 per ton, said Ben Hushon, an agronomist and partner at the Mill chain of agricultural products stores, one company that has worked with farmers to experiment with soil carbon markets.

That price translates to income of around $15 to $30 per acre, according to an estimate from Duke University.

By comparison, an acre of corn was worth more than $900 last year, while soybeans were $650 per acre, according to the U.S. Department of Agriculture.

There is already rising tension over who should receive soil carbon storage payments - landowners or farmers - given that many farmers are only renting the land they work, Hushon said.

But the most frustrating aspect for many farmers, he said, is that those already growing using sustainable practices often are not rewarded, with corporations purchasing soil carbon credits mainly interested in trying to change farm practices.

"That's resulted in disappointment, frustration and anger," Hushon added.

Still, the incentives are working for Loy Sneary and his son, who raise cattle on 7,000 acres near Bay City, Texas.

They recently shifted their operations to move their herds frequently and let used pastures sit for months before the animals return.

The pair have already seen the regrowth of native grasses with deeper carbon-holding roots, Sneary said - and they have halted the use of herbicides on the land.

"The more we move the cattle, the faster the soil will heal and the more carbon we'll sequester," he added.

While the new approach took upfront investment, Sneary said carbon storage payments he is receiving will let him pay off his costs by the second year.

Neighbors initially thought he was "crazy", he admitted.

But "now we have a lot of folks saying, 'Maybe we should take a second look at this' – especially now that we're getting a payment for it," he said.