Reducing tillage and carbon dioxide

Mounting concerns about the buildup of carbon dioxide in the atmosphere has led many to ask how the world's food supply could be affected. In holding back the building carbon dioxide tide, it turns out the food supply may be part of the solution. Charles Rice, a professor of soil microbiology at Kansas State University, insists it is.

In addition to his professorial duties, Rice is a fellow of the Soil Science Society of America and American Society of Agronomy. He is also director of the Consortium for Agricultural Soils Mitigation of Greenhouse Gases. The consortium brings together 10 institutions to conduct research on how agricultural soil can sequester carbon dioxide and still remain beneficial for farmers.

Fresh from testimony before the Senate Agricultural Committee, Rice recently spoke with Delta Farm Press about his work, the potential of farming practices to buy time and the fledgling carbon credits market. Among his comments:

DFP: How do you approach the topic of global warming with farmers?

PRICE: (Global warming) is definitely not a foregone conclusion with farmers. There's even debate — although less so — within the scientific community. I work with a grass-roots group, Kansas Coalition for Carbon Management. It's made up of farming organizations, commodity groups, and others. The group meets quarterly, and I am involved. It's an informed group and includes many farmers.

Sure, there are skeptics. But the things I work with are win/win for everyone. Even if global warming proves to be wrong, there are still opportunities for gaining benefits from this work.

DFP: In your congressional testimony, you said, “Currently, the amount of carbon dioxide in the air is increasing by over 1,500 million metric tons per year.” Can you put that into context?

PRICE: In the last 100 to 150 years, there has been about a 40 to 45 percent increase in carbon dioxide in the atmosphere. We've gone from 260 parts per million up to almost 370 parts per million currently.

In the 1800s, a portion of that came from clearing of lands. When you cut forests and plow up grasslands, carbon dioxide is released because of soil microbes decomposing organic matter. Over the last 50 years or so, some 80 percent of the carbon dioxide increase is due to the burning of fossil fuels.

This exponential increase in carbon dioxide doesn't have any appearance of slowing down because of our need and demand for energy.

So, we know carbon dioxide is increasing. The implication is that it may cause warming of the atmosphere. carbon dioxide, as a compound, absorbs heat. Some carbon dioxide is good — without it, our planet would be much colder. The question is: how much carbon dioxide is too much of a good thing?

If we want to reduce the carbon dioxide in the atmosphere, there are several strategies. Long-term, we can reduce our reliance on oil and coal and become more fuel efficient.

Another, short-term strategy and the one I'm working on, is to reduce carbon dioxide through sequestration through soils. Basically, that means using plants to take up carbon dioxide as they grow. Once a crop is harvested, the leftover material is left in the soil. How we manage the soils determines how much carbon dioxide stays there. We want to know how much agricultural land can retain or store carbon.

DFP: What is the potential for this?

PRICE: Using a variety of crop and soil management practices, somewhere around 15 to 20 percent of the current U.S. carbon emissions can be recycled or stored on the soil. That's due to a menu of cropping systems. Any reduction in tillage encourages the retention of carbon in soils as organic matter. No-till is the ultimate example of this.

There's enough data available — and I'm working in producer fields on this — that con-till and no-till can do this job.

Another practice that's important is wheat/fallow rotations. The fallow period is a time when there are no plants growing and no carbon going into the soil. At that time, microorganisms are decomposing organic matter and there's a loss of carbon.

With better water conservation, newer varieties and different tillage systems, we can go with two crops every three years. In some cases, crops can be grown every year. When there are crops being grown yearly, there's a large increase in the carbon content of soils.

Another practice is the Conservation Reserve Program (CRP) taking marginal lands out of production and planting them back to perennial crops. In Kansas, that's planting land back to native grasses. In other areas, it might be going to woodlands.

DFP: If fossil fuel use stayed at current levels and everyone around the world adopted con-till or no-till, what kind of carbon sequestration percentage could we get to?

PRICE: It would depend on the level of adoption. But there have been estimates that if the world adopts these practices, we will stabilize the increase in carbon dioxide for the next 30 to 50 years. It can make that big of a difference — we can use agricultural lands as a mitigation strategy.

Now, there are several things to point out. First, the 30- to 50-year estimate shows this has an impact and would allow us a window to discover and improve energy technologies and also make them economically feasible. But that timeframe also shows that this won't be a permanent solution. What happens is there's only so much carbon that can be held in soils. Eventually, the capacity is reached and after that carbon emission will increase again.

DFP: Since you have the ear of politicians, what are their attitudes towards your research now versus a decade ago?

PRICE: It's true — I've worked with members of Congress on this. They've moved from saying, ‘Global warming doesn't exist’ to a great awareness and appreciation (for the subject). I think the current administration is pursuing the research and building a research base. They're not enacting policies yet, though.

The two senators from Kansas — Roberts and Brownback — are highly involved and well-informed on global warming. The senators from Iowa, Nebraska and Indiana are also very active.

DFP: How about the carbon credits market? What are your views on that?

PRICE: It's in infancy, right now. There are a couple of ways producers could benefit from this.

From the governmental side, there is increasing interest in having farmers provide ‘environmental services.’ Those services include water quality, wildlife and soil quality. In the future, government programs may be directed to enhance or reward such services.

On the private market side, there is an emerging interest in ‘carbon credits.’ That's where companies that emit carbon dioxide — like power plants — could offset those emissions by paying farmers to do carbon reduction practices. Farmers could be paid for going with reduced tillage, rotations, or planting grasses or trees.

There are currently some regional projects that have been instituted. The Chicago Climate Exchange is setting up something like a stock market. The energy companies can go there and buy carbon credits. The companies are looking for off-setters of carbon — in this case, agricultural producers.

That's just been started and producers in Kansas, Iowa, Nebraska and the Delta could benefit. Right now, the prices for these credits is pretty low. Nobody will say publicly what the prices are, but I suspect they're around $1 or $2 per year. No one will get rich off this, but it does provide some income.

Another group, Environmental Defense, has a project going on with Entergy (a Delta-based energy company). Entergy has a 10-year carbon lease with a no-till farming organization in the northwest. They're actually paying farmers under contract to farm no-till for the next decade.

In both these examples, there must be an aggregator. A company isn't going to want to work with 1,000 farmers — they want to work with an organization that represents 1,000 farmers. The companies don't want 1,000 contracts floating around. (Such organizations) need to develop in agricultural areas.

The point is agricultural soils can play a key role in reducing carbon dioxide in the atmosphere. Plus, there are all kinds of ancillary benefits. The greatest need is to learn how to develop these markets.

e-mail: [email protected]

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.