As Corn Yields in the US Grow, So Does Sensitivity to Drought

Corn yields have been increasing in the U.S. Midwest’s Corn Belt between 1995 and 2012, but the crop’s sensitivity to drought appears to be increasing as well, according to a new study by David Lobell and colleagues. In fact, drought sensitivity has increased steadily over the past 18 years, as plants have been bred to grow at higher planting densities. However, densely planted corn appears to be unexpectedly more sensitive to water scarcity, the researchers note. One key driver of this trend appears to be water vapor pressure deficit (VPD), which is a measure of air dryness. Corn yields fall under the high VPD levels associated with drought. If climate predictions for future drought conditions in the area are correct, the trend in VPD levels would reduce corn yields by about 15 percent over the next 50 years -- or possibly by 30 percent if the plants become increasingly drought sensitive. In a related Perspective, Donald Ort and Stephen Long note the implications of this finding for the future of U.S. agriculture, which currently provides half of the global corn exports.

"Greater Sensitivity to Drought Accompanies Maize Yield Increase in the U.S. Midwest," by D.B. Lobell at Stanford University in Stanford, CA; M.J. Roberts at University of Hawaii at Manoa in Honolulu, HI; W. Schlenker at Columbia University in New York, NY; N. Braun; R.M. Rejesus at North Carolina State University in Raleigh, NC; B.B. Little at Tarleton State University in Stephenville, TX; G.L. Hammer at The University of Queensland in Brisbane, QLD, Australia; G.L. Hammer at Queensland Alliance For Agriculture and Food Innovation in Brisbane, QLD, Australia.

Science Magazine 2nd May 2014