Elevated carbon dioxide in atmosphere trims wheat, sorghum moisture needs

March 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: Replicating Climate Change to Forecast its Effects

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

Related Stories

Replicating Climate Change to Forecast its Effects

December 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.

The Baltic Sea contributes carbon dioxide to the atmosphere

October 11, 2011

The Baltic Sea emits more carbon dioxide than it can bind. Local variations have increased the exposure of the Bay of Bothnia. These are the results from a study of how carbon dioxide flows between the water of the Baltic ...

Poorer quality wheat when carbon dioxide levels in the air rise

December 11, 2012

Rising levels of atmospheric carbon dioxide have a negative impact on the protein content of wheat grain and thus its nutritional quality. This is the finding of researchers at the University of Gothenburg, Sweden, in a recently ...

Recommended for you

Can Paris pledges avert severe climate change?

November 26, 2015

More than 190 countries are meeting in Paris next week to create a durable framework for addressing climate change and to implement a process to reduce greenhouse gases over time. A key part of this agreement would be the ...

Amazon deforestation leaps 16 percent in 2015

November 28, 2015

Illegal logging and clearing of Brazil's Amazon rainforest increased 16 percent in the last year, the government said, in a setback to the aim of stopping destruction of the world's greatest forest by 2030.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.