The new findings are based on on-going open-air research at the University of Illinois at Urbana-Champaign and results gleaned from five other temperate-climate locations around the world. According to the analysis, published in the June 30 issue of the journal Science, crop yields are running at about 50 percent below conclusions drawn previously from enclosed test conditions.
Results from the open-field experiments, using Free-Air Concentration Enrichment (FACE) technology, "indicate a much smaller CO2 fertilization effect on yield than currently assumed for C3 crops, such as rice, wheat and soybeans, and possibly little or no stimulation for C4 crops that include maize and sorghum," said Stephen P. Long, a U. of I. plant biologist and crop scientist.
FACE technology, such as the SoyFACE project at Illinois, allows researchers to grow crops in open-air fields, with elevated levels of carbon dioxide simulating the composition of the atmosphere projected for the year 2050. SoyFACE has added a unique element by introducing surface-level ozone, which also is rising. Ozone is toxic to plants. SoyFACE is the first facility in the world to test both the effects of future ozone and CO2 levels on crops in the open air.
Older, closed-condition studies occurred in greenhouses, controlled environmental chambers and transparent field chambers, in which carbon dioxide or ozone were easily retained and controlled.
Such tests provided projections for maize, rice, sorghum, soybean and wheat ?the world's most important crops in terms of global grain production.By 2050 carbon dioxide levels may be about 1.5 times gre
Source:University of Illinois at Urbana-Champaign