Elevated carbon dioxide in atmosphere trims wheat, sorghum moisture needs

Mar 26, 2013

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 of water," said K-State 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 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 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. is decreased.

Studies done subsequent to the early work confirmed the findings.

Over the past few months, the researcher said she's heard people comparing the dry summer of 2012 with the Dust Bowl years of the 1930s and the drought of the mid-1950s in Kansas.

The first of were made in 1958, so while scientists do not know what the concentration of CO2 was in the 1930s, Kirkham said, she used the data that she and her students collected to calculate how much the water use efficiency of sorghum has increased since 1958, which was about the time of the middle of 1950s drought.

"Due to the increased in the atmosphere, it now takes 55 milliliters (mL) less water to produce a gram of sorghum grain than it did in 1958," she said. "Fifty-five mL is equal to about one-fourth of a cup of water. This may not seem like a lot of water savings, but spread over the large acreage of sorghum grown in Kansas, the more efficient use of water now compared to 1958 should have a large impact.

"The elevated carbon dioxide in the atmosphere in 2012 ameliorated the drought compared to the drought that occurred in the mid-1950s."

At the basis of Kirkham's book are experiments that she and other researchers conducted in the Evapotranspiration Laboratory at K-State from 1984-1991.

"They were the first experiments done in the field in a semi-arid region with elevated carbon dioxide," Kirkham said. The lab no longer exists, but the work continues.

Explore further: Dead floppy drive: Kenya recycles global e-waste

More information: More information about Kirkham's research is available at www.agronomy.ksu.edu/MBKirkham

add to favorites email to friend print save as pdf

Related Stories

Replicating Climate Change to Forecast its Effects

Dec 17, 2009

(PhysOrg.com) -- Agricultural Research Service (ARS) scientists are replicating the effects of climate change to see what the future holds for soybeans, wheat and the soils where they grow.

Recommended for you

Dead floppy drive: Kenya recycles global e-waste

17 hours ago

In an industrial area outside Kenya's capital city, workers in hard hats and white masks take shiny new power drills to computer parts. This assembly line is not assembling, though. It is dismantling some ...

New paper calls for more carbon capture and storage research

22 hours ago

Federal efforts to reduce greenhouse gas emissions must involve increased investment in research and development of carbon capture and storage technologies, according to a new paper published by the University of Wyoming's ...

Coal gas boom in China holds climate change risks

Aug 22, 2014

Deep in the hilly grasslands of remote Inner Mongolia, twin smoke stacks rise more than 200 feet into the sky, their steam and sulfur billowing over herds of sheep and cattle. Both day and night, the rumble ...

User comments : 0