During the debate in Congress over climate change legislation, no-till is seen as one way to sequester carbon in the soil.

By practicing "no-till," a farm could earn carbon offsets, which he could then sell to gain another revenue stream.

But there's a potential catch, say proponents. In Congress, no-till really means "never-till."

What's the difference? Depending on the farmer, they can either be identical or very different, say agricultural experts.

Once the soil is plowed, the carbon is no longer sequestered. Because of that, to maintain a carbon offset, a farmer would never till his field.

This never-till practice is gaining popularity in some areas of the country. One is southern Virginia.

Paul Davis, a retired Virginia Polytechnic Institute and State University agricultural extension agent, says a growing number of farmers in parts of Virginia use "never-till."

It's a method in which farmers never plan to till because of the soil qualities they gain, says Davis, who specialized in crops and soils.

"A lot of farmers will no-till one crop, but they'll till the land to plant a crop next year," Davis says. "We don't till the land at any time before or after any crops we're growing."

Nobody in his area is doing carbon trading because the value received per ton of carbon is not worth consideration for the short-term, he said. Many growers in Virginia are waiting for potentially better opportunities later in the legislation Congress is considering.

"Someone asked me, was it an evolution or a revolution in agriculture with never-till, and I think it's just an evolution," Davis says. "You're saving not only soil, oil and toil, but now you benefit from nutrient and fertilizer savings. It's been a tremendous program here in the southern part of Virginia, and it's spreading very fast."

"Not many places can do what we're doing," Davis says. "We're growing carbon to put in the soil. These plants are converting the CO2 into a skeleton of plant materials. We can actually harvest the grains and leave the residue on the soil surface. It decays slowly and is improving everything in the soils."

Colfax, Wash., farmer John Aeschliman is a no-till pioneer. He has used single-pass no-till on his operation for about 30 years. Aeschliman's area receives about 20 inches of rainfall per year.

"It doesn't release carbon, it doesn't let the moisture out and it doesn't disturb the microbial system that's breaking down your residue," Aeschliman says.

In a single-pass system, the farmer fertilizes and seeds all in one pass, Aeschliman says.

In a two-pass system, a farmer fertilizes first and then plants the seed with a no-till drill.

Aeschliman said there can be some confusion over the name.

"There's a lot of things that are called no-till that really almost aren't no-till," he says. "You have a single-pass no-till, a two-pass no-till and then people who sometimes, because they can't get through the straw for whatever reason, they till it in the fall and the next spring they use a no-till drill on it and they call it no-till."