Changing climate will reduce corn production, University of Minnesota study predicts

Minnesota corn farmers enjoyed record yields in 2015. But that may look like the good old days in a generation or two if a new study from the University of Minnesota proves true.

Changing climate could dramatically reduce corn production in the coming decades, according to the research. Higher summer temperatures — interspersed with cycles of drought followed by heavy rain — could shrink the number of bushels per acre by 15 to 50 percent beginning midcentury, scientists said.

Tracy Twine, lead researcher on the project and an associate professor in the Department of Soil, Water and Climate, hopes the study will alert the agriculture industry and speed up strategies to adapt, such as developing and field testing more heat-tolerant corn varieties, or considering whether irrigation might need to be a future option in some locations.

Officials from the corn growers industry had not seen the study, but expressed confidence that corn breeders can develop new seeds that can better tolerate drought and other environmental stress.

"It's not like we would say this is cause for alarm," said Paul Meints, research director for the Minnesota Corn Growers Association.

Twine said the study ran simulations using six different climate computer models and a variety of scenarios about the amount of global warming gases in the atmosphere. It focused on Iowa because of its central location in the Corn Belt and its long-term status as the nation's largest producer of corn.

The two climate variables most important to corn production are air temperature and precipitation, Twine said, and most computer models predict a range of higher average temperatures, less midsummer rain, and five to 20 additional days of 95-degree temperatures in the Midwest by 2050.

If those changes occur, she said, corn will grow earlier and mature faster, leaving it vulnerable to extreme heat that will affect photosynthesis, reduce carbon assimilation and cause declines in pollination and grain development.

"If the plant matures quicker and then faces higher stress later with higher temperatures and not enough rain, then that decreases the yield," she said.

Minnesota corn growers produced a record 1.43 billion bushels in 2015, with yields that averaged 188 bushels per acre, 11 bushels above the previous record set in 2010, according to the U.S. Department of Agriculture.

Twine's research was funded in part by the USDA and the U.S. Department of Energy, with collaboration from the International Center for Tropical Agriculture in Kenya. It was published in the journal PLOS ONE this week.

In some computer simulations, researchers also "turned off" the factor of rainfall, hypothetically assuming that the corn would receive all the moisture it needed each season. In those scenarios, Twine said, bushels per acre still dropped 10 to 20 percent by the end of the century based on projected higher air temperatures alone.

Twine said the findings are based on what would happen if farmers use the same varieties of corn and do not use any irrigation. "This is mostly to quantify what would happen if we keep going like we are right now," she said.

Meints from the corn growers association agreed that potential changes in climate are a concern, and something that both public universities and private companies are addressing.

"The agriculture industry and particularly the corn breeding industry has already been working on releasing some new genetic lines that have better drought tolerance," he said.

Seed industries are keeping track of climate and other environmental influences in their breeding efforts, he said, and have a good record in developing technology quickly.

"Our awareness of climate change directs our research," Meints said, "as well as our trust in other aspects of the industry to keep pace as fast as they can with what we see coming out in the future."

Tom Meersman • 612-673-7388