Plenty has been written about concerns over elevated levels of carbon dioxide in the earth’s atmosphere, but a Kansas State University researcher has found an upside to the higher CO2 levels. And it’s been particularly relevant in light of drought that overspread the area in recent months.
“Our experiments have shown that the elevated carbon dioxide that we now have is mitigating the effect that drought has on winter wheat and sorghum and allowing more efficient use of water,” said K-State agronomy professor Mary Beth Kirkham.
Kirkham, who has written a book on the subject, “Elevated Carbon Dioxide: Impacts on Soil and Plant Water Relations,” used data going back to 1958. That’s when the first accurate measurements of atmospheric carbon dioxide were made, she said.
“Between 1958 and 2011 (the last year for which scientists have complete data), the carbon dioxide concentration has increased from 316 parts per million to 390 ppm,” she said. “Our experiments showed that higher carbon dioxide compensated for reductions in growth of winter wheat due to drought. Wheat that grew under elevated carbon dioxide (2.4 times ambient) and drought yielded as well as wheat that grew under the ambient level carbon dioxide and well-watered conditions.”
The research showed that sorghum and winter wheat used water more efficiently as a result of the increased levels of carbon dioxide in the atmosphere, Kirkham said. Because elevated carbon dioxide closes stomata (pores on the leaves through which water escapes), less water is used when carbon dioxide levels are elevated.
Evapotranspiration is decreased.
Studies done subsequent to the early work confirmed the findings.
More information about Kirkham’s research is available at www.agronomy.ksu.edu/MBKirkham.