Carbon dioxide has been increasing at a rate of .4 percent per year. Because plants take in carbon dioxide, this has been a positive change for plant production. In fact, rising carbon dioxide has the potential to increase yields by as much as 30 percent. But those yields are unlikely to be realized with today's soybean, because varieties are adapted to the atmosphere of a century ago.

At the same time, ozone has a negative effect on crops. The gas has increased an average of 1 percent per year and is already estimated to have cost agriculture in the United States over $2 billion in lost production. And soybeans are particularly sensitive to ozone. The problems of surface ozone changes are regional, depending in part on proximity to urban and industrial areas.

The main research facility for the project is located on 80 acres of farmland just south of the main University of Illinois campus at Urbana.

"As the name SoyFACE suggests, the primary focus of the research is on soybeans, but the impact of atmospheric changes on corn is also under investigation," said Stephen Long, professor in the U of I's Crop Sciences. "The project uses a new technology known as Free Air Concentration Enrichment (FACE). This consists of a network of tubing that delivers different concentrations of ozone and carbon dioxide into the air that surround the soybean and corn plants in the test field."

He notes that the system creates a kind of greenhouse without the walls and glass around it. The higher concentrations of gases dissipate as they rise out of the study area and into the general atmosphere without causing any change to the surrounding area.

"The open-air field laboratory gives us an opportunity to look at a whole system in a 'real-world' way that isn't possible in greenhouses or controlled chambers," Long said. "In the FACE facility, we can look at all the biological processes what's happening with the plants and soil as atmospheric gases change."

They have already observed some remarkable variations due to the changes in atmosphere inside the ring. Soybeans growing inside the ring of tubing stayed greener longer because of the elevated level of carbon dioxide than the soybeans growing just inches away, outside of the experimental arena.

"The effects of atmospheric gases on a cropping system are very complex," Long said. "Once we understand the science behind the changes we can begin to genetically modify the crop or select genotypes and management systems that take advantage of those changes to increase production under levels of atmospheric gases predicted for the future."

In mimicking the anticipated atmosphere of 2050, the researchers have found that soybean yields increased by 15 percent at the elevated carbon dioxide levels. Although the response was smaller, significant yield increases were observed in some corn cultivars.

"Other results suggest that even greater yield increases could be possible," Long said. "Decreased evaporation of water also might result in stress damage in hot years. By contrast, a 20 percent increase in ozone depressed soybean yields by 15 percent. Work during the coming growing season will aim to establish how rising ozone and carbon dioxide interact."

Although there are several other facilities of this kind around the world studying different crops, this one is the largest. The only other FACE crops facility in the United States is in Arizona and is used for cotton and wheat research. The work is funded by the Illinois Council for Food and Agricultural Research (C-FAR).