| Stephen Long
Robert Emerson Professor
Department of Crop Sciences
(217) 333-2487; firstname.lastname@example.org
USDA-ARS and Professor
Department of Crop Sciences
(217) 333-2093; email@example.com
Carbon dioxide (CO2) in the world’s atmosphere is on the rise. In the last century, it rose 20 percent and this geologically unprecedented pace will continue, resulting in an atmosphere in 2050 containing 50 percent more CO2 than it did in 1900. While this enrichment of the atmosphere portends certain hazards, of which global warming is the most publicized, it also offers the potential for increases in plant production. This will be a result of increased photosynthetic efficiency at elevated CO2 in important crops such as soybean, wheat, and oats, as well as making it possible for all crop plants to be more water efficient. Carbon dioxide is, in effect, a fertilizer and is used as such in greenhouse production of horticultural crops. But just as germplasm had to be specially selected to achieve the potential increases in yields provided by nitrogen fertilization, so too will selection be necessary to maximize response to the rise in CO2. However, there is little evidence that plant breeding has, to date, selected lines capable of fully realizing this potential.
Perhaps less well known is the fact that the pollutant ozone also is on the rise in the portion of the atmosphere closest to the earth’s surface. In fact, in agricultural areas of the industrialized regions of the world, such as the Midwest, ozone is increasing more rapidly than is CO2. The effects of ozone pollution on crop production already cost U.S. agriculture an estimated $2 billion in lost production per year. In central Illinois, ozone reaches, on average, 60 parts per billion (ppb) each day during the growing season. On occasional days, levels exceed 100 ppb. Levels above 40 ppb decrease soybean production (Figure 1), but the transient and unpredictable nature of ozone pollution levels has prevented successful selection for ozone tolerance in sensitive crop species.
Until recently, information on crop responses to global atmospheric change has depended on experiments in greenhouses or small outdoor enclosures. While much of importance has been learned from these works, enclosing crops in a greenhouse affects growth, production, and appearance to an extent that they respond very differently to environmental treatments than do plants in the field. The lack of a realistic experimental system to investigate the underlying physiological, molecular, and genetic bases of how specific crop plants respond to the interacting components of atmospheric change has been a considerable obstacle in a now-highly politically charged research arena.
SoyFACE is an innovative facility for growing crops under production field conditions in an atmosphere that is anticipated for the middle of this century, namely one with higher levels of carbon dioxide and ozone. SoyFACE is designed to discover the effects of atmospheric change on the agronomy and productivity of Midwestern crops as well as to find solutions that will lead to crops better adapted to this future. This unique facility and the highly interdisciplinary research teams that it serves seek answers to important questions, including:
As the name suggests, the primary research focus is on soybean, but the impacts of atmospheric change on corn also are under investigation. SoyFACE is situated on 80 acres at the southern edge of the new South Farms of the University of Illinois, making it the largest “open-air laboratory” worldwide for investigating the impacts of the changing composition of the atmosphere on crops. It exploits a new technology, Free Air Concentration Enrichment (FACE), now being implemented at four other international sites. It consists of rings (each approximately 70 feet in diameter) of pipes that release carbon dioxide or ozone into the wind as it flows across the crop (Figure 2). A computer continuously measures wind speed and direction and the gas concentration within the ring to determine which pipes release the gas and how much they release. The carbon dioxide or ozone is released into the naturally moving air so that the concentration within the ring is elevated to a preset level. The rings use about a ton of carbon dioxide or about a pound of ozone a day. Downwind of the rings, the added gas is diluted quickly in the flowing air so that concentrations are close to background within about 300 feet.
A standard corn-soybean rotation is practiced, so that each year, 40 acres are in each crop. In 2001, the western half was in soybean and the eastern in corn, switching in 2002. In 2001, four elevated and four ambient CO2 rings were established within the 40 acres of soybean. In 2002, corn is being grown in these eight rings. Twelve additional rings have been added to the 40 acres now in soybean: four ambient, four elevated CO2, and four elevated ozone. In 2003, four more rings will be added to study the interactive effects of elevated ozone and CO2 (Figure 3). With the development of funding and appropriate technology, there are plans to add free air temperature increase treatments to simulate the global warming that is anticipated for the Midwest by the middle of the century.
How well does the present system work? The fast computer feedback results in surprisingly good control; the concentration achieved is within 20 percent of the target for 97 percent of the time. Figure 4 provides a graphic illustration. Increased CO2 decreases evaporation of water and therefore cooling of leaves in sunlight. As a result, leaves are warmer. In Figure 4, an even increase of temperature of about 5°F across the half of the ring illustrated can be seen. One half of each ring is reserved for studies on one commonly used cultivar, the other for trials of a range of germplasm.
The SoyFACE project, while just getting underway, has already resulted in important discoveries. In 2001, growth of soybean in elevated CO2 showed significant increases in photosynthetic carbon uptake and decreases in water loss from emergence to final senescence of the crop. Total soybean seed production was increased from 59 to 69 bushels per acre. Although large, this 17 percent increase is less than half of the 40 percent increase in photosynthesis, documenting a large unrealized potential of modern cultivars in responding to carbon dioxide fertilization. The yield increase was in the number rather than the size of seeds. There was no significant change in oil and protein content, but isoflavone content rose significantly. Great variation was observed within the germplasm trials, with yield increases from 10 to 30 percent. The most striking effect of elevated CO2 was a delay in crop senescence of almost two weeks, which was apparent in all germplasm (Figure 5).
What factors have led to the development of this leading international facility in Illinois? The unique combination of expertise on the UIUC campus, including the Illinois State Water Survey, National Soybean Research Laboratory, USDA Agricultural Research Service, Keck Center, and National Center for Supercomputer Applications provides as large a range of complementary expertise in crop sciences and related expertise as could be found anywhere. This unusual concentration of expertise allows what is probably the most comprehensive examination of the growth and environmental relations of the soybean crop, from gene expression, nodule development, and germplasm differences to final yield, seed quality, and soil carbon storage.
Corn and soybeans were planted in 153 million acres of the contiguous United States in 2002. In terms of area sown, corn and soybeans are the number one and number two crops of the U.S. Central Illinois is at the center of this system and among the most productive areas for both crops. While CO2 is rising at the same rate across the world, ozone is not affecting the soybean growing areas equally. The largest increases in ozone have been and continue to be in the Midwest, the eastern U.S., Western Europe, and China, with little increase in the soybean growing regions of South America. Therefore, developing tolerance is critical to the competitiveness of production in Illinois. Corn-soybean is the largest ecosystem of the contiguous U.S. The system is one of the most important not only for U.S. exports but also for international food security. A small change in yields in this system has a profound effect on world food supply and future surpluses/shortages on the world market. The research from SoyFACE will allow better predictions of the future supply.
The size of the U.S. soy-corn system means that any changes in its interaction with the environment can have profound influences on water and air quality, as well as on regional climate within the U.S. For example, rising CO2 and ozone both are predicted to decrease the rate of evaporation of water from these crops into the atmosphere. During the summer, these crops are the major source of water vapor to the westerly flow of air across the Corn Belt. Decreased evaporation would result in lower rainfall in the east and increased surface temperature within the Corn Belt. SoyFACE offers the first opportunity to discover if these predictions of lower evaporation occur under realistic open-air conditions and will provide a sounder basis for predicting future regional climates.
Globally, industry and transportation are adding almost seven billion tons of carbon to the atmosphere each year. Fortunately, only about half of this remains in the atmosphere. Trees and crops remove more carbon in the process of photosynthesis than they return in respiration. Without this, global atmospheric and climate change would occur even more rapidly. But can we rely on this protection from plants in the coming decades? Soils of the Corn Belt historically have held large deposits of carbon. Theoretical and enclosure studies have produced conflicting predictions of carbon content in the future. SoyFACE is allowing us to determine both whether carbon accumulation will occur with atmospheric change and what management will maximize this accumulation. As the largest ecosystem in the U.S., any change in carbon uptake in soy-corn will have a profound effect on the rate of global rise in CO2.
SoyFACE is having a major impact on our understanding of how global atmospheric change will impact crops over the coming decades. However, the atmosphere already has changed substantially in ways that directly affect crops and crop systems. By discovering how to adapt our crops and crop systems to the future atmosphere, we also will adapt them to the changes that have already occurred.
SoyFACE also provides a unique training environment for future leaders in this emerging research area. (Figure 6) Over 40 graduate students, undergraduates, and postdoctoral fellows are undertaking research in SoyFACE, developing large teams to gain an integrated picture of the effects of atmospheric change from soil chemistry and water balance to gene expression and metabolism. The opportunities within SoyFACE are leveraging expertise from a wide range of U.S. universities (eight), USDA groups (five), and national laboratories (three). It also has attracted experts from a wide range of European, Australian, Canadian, and South American institutions.
Figure 6. A montage of research in SoyFACE from germplasm trials and molecular studies to soil analyses and final harvest.
The SoyFACE facility and project were launched with enabling funding from the Sentinel program of C-FAR (Illinois Council for Food and Agricultural Research). With this key funding in place, ADM, Argonne National Laboratory (ANL), Pioneer Hi-Bred, USDA-ARS, and USDA-NRI have provided funding and further support that has greatly expanded and enhanced the facility.
College of Agriculture, Consumer and Environmental Sciences
University of Illinois Extension
© 2002 University of Illinois
Email site problems to the webmaster