When the heavy rains came to Iowa this spring, corn farmer Dave Miller tilled the rolling portions of his 255-hectare plot. Cutting into the soil slows runoff and, particularly, prevents water from gouging big gullies in the fertile but softly held land. A few years back such tilling would have cost him money, thanks to an attempt to pair farmers improving the carbon management of their soils and companies looking to reduce pollution.

"We know that raising soil organic matter is good for soil, good for society and good for climate," says Miller, whose day job is as an economist for the Iowa Farm Bureau (IFB). He once ran the nation's largest agricultural carbon credit service. The idea is simple: The soil is one of the best places to put the carbon dioxide causing climate change, which has reached new highs in the atmosphere. Plants help put the carbon into the soil through photosynthesis—knitting CO2 and water into carbohydrates using the power of sunlight. And farmers can boost the process further by turning some of those plants into charcoal—or biochar, as advocates of the approach like to call it.

But farmers need incentives to adopt such practices. One of the few efforts to encourage farmers across the U.S. to tend to their land and the atmosphere alike was the now defunct Chicago Climate Exchange (CCX), a trading outfit that brought together a set of companies that volunteered to adopt a cap on CO2 pollution and traded carbon credits to meet that goal.

With the CCX, Miller set out to craft a climate program that would also "work for agriculture," as he puts it, rather than being designed by "suits in Chicago." In short, a program like CCX is put in place that establishes a limit for greenhouse gas emissions by a set of companies, such as electric utilities. Polluting companies in the program would have to reduce their own emissions or buy pollution-reduction credits from others. The farmers—represented by the IFB—would provide some of those extra CO2 reductions to the CCX market.

At its peak, Miller's program enrolled more than 4,000 farmers, ranchers and foresters across 31 states. A similar program from the North Dakota Farmers Union engaged yet more farmers. The Iowa program’s rules as devised by Miller and his colleagues were simple: no till for five years. By not turning over the soil and exposing organic matter to the sky, Miller and farmers like him kept carbon in the ground. (The practice is not a panacea, however—it does not store carbon in all landscapes.) The no-till policy helped growers to both build better soil and combat climate change. In exchange, the farmers received roughly $1 per acre. "Most participants were not in it for the money," Miller notes, but instead hoped to figure out how to adapt to potential new rules for CO2 pollution. "They were there to learn."

Between 2003 and 2010 Miller’s program covered roughly 810,000 hectares of farmland, more than two million hectares of rangeland and around 400,000 hectares of forest. "We were gearing up for millions of tons of carbon offset credits a year," Miller recalls. The service had plans to go national by selling credits in a proposed nationwide cap-and-trade program, although the approach did face criticism from environmentalists, among others. "It wasn't about generating a lot of money,” Miller says. “It was about a low-cost solution to climate change."

Instead, there was no national program to combat climate change, neither cap-and-trade nor any other alternative, after legislation to establish such a program failed to pass the U.S. Congress in 2009. Part of the reason that the climate legislation fell short is that the American Farm Bureau, of which the IFB is a part, pulled its support at the last moment. "We do think cap-and-trade would significantly impact the agriculture industry," particularly in terms of energy costs, explains Mace Thornton, a Farm Bureau spokesperson. The organization, he adds, also has "concerns about agricultural lands being used as a carbon sink and taking it out of food production."

As a result, the plans to expand Miller’s service fell apart almost immediately—and so did the CCX market as a whole, shutting down in 2010. "We were one of the few participants that honored all our commitments," Miller says. "We lost money doing that."

There's more tilling happening these days in the Corn Belt—and more CO2 piling up in the atmosphere. The U.S. Department of Agriculture has rolled out conservation programs to help farmers build up carbon in the soil and has supported more research on soil health, which will provide some climate relief in the absence of a cap-and-trade market for greenhouse gases. "We thought that was the best market-based approach to deal with climate change," says Roger Johnson, president of the National Farmers Union and a North Dakota farmer. "That's clearly not going to happen for some while, if ever."

For Miller's part, when torrential rains of more than six inches came earlier this year, he tilled the slopes to protect the land. "Does that release carbon? Yes it does," Miller acknowledges. Instead of reducing the risk of climate change, farmers will just have to learn how to adapt to it—until given a reason to do otherwise.