At the University of Minnesota, researchers are growing corn in greenhouses like it's the year 2065.
The effort is part of a long-term plan to study how corn will grow under weather conditions considerably different from today's, predicted in climate change models for a half-century out.
"Many models show that with increasing temperatures we could be seeing a reduction in corn yields, so that's something we would like to investigate under controlled conditions," said Tim Griffis, University of Minnesota professor of biometeorology and one of several researchers directing projects.
Different models predict that corn yields could drop from 30 to 80 percent by the end of the century depending on locations and as a result of extreme heat, wetter springs, more intense rainstorms and drier summers.
The setting for the experiments is a state-of-the-art greenhouse addition on the University's St. Paul campus, funded mainly by the National Science Foundation. Researchers have constructed huge chest-high planters that contain 55 inches of soil excavated layer by layer from a traditional crop farm near Kenyon in southeastern Minnesota. To match the soil density, they painstakingly installed the layers in the same order within the containers, one inch at a time.
Six of the containers — each with 9.5 tons of soil — are growing small groupings of 18 corn plants that last week reached the open greenhouse roof and were tasseling.
Three of the containers are a control group and are receiving the same amount of rainfall that's been typical for southeastern Minnesota during the past 30 years. Three other containers are an experimental group that received 20 percent more rain than usual in the spring and are receiving 10 percent less rain than normal in the summer — similar to what climate models project for the years 2045 to 2065.
Researchers will compare the yields from each group, as well as nitrogen use and greenhouse gas emissions from the soil. Sensors at different soil depths also allow them to collect data on soil temperatures and soil water content.
"We're trying to assess how farmers can adapt to different precipitation by understanding how soils respond to a different climate," said Peter Turner, a graduate student involved in the research, which is funded in part by the Minnesota Corn Research & Promotion Council.
John Baker, research leader for the Agricultural Research Service of the U.S. Department of Agriculture, is also using the greenhouse corn to study a more immediate problem: the amount of nitrogen fertilizer that runs off farm fields as nitrate or is changed to nitrous oxide and escapes to the atmosphere. He is also studying the relationship between spring rains and extra water applied to replicate snowmelt and whether that changes the nitrate levels moving through the soil.
Corn is a phenomenally productive crop that needs a lot of nitrogen in June and July, Baker said, and if climate change causes more intense storms, that could cause even greater fertilizer loss, runoff and pollution.
"We're investigating whether there are things we can do to reduce those losses with respect to landscape water storage," he said. Areas that flood consistently might be better used to store water instead of growing crops, he said, and that water could be used to irrigate upland areas that are predicted to get less rain in late summer (instead of depleting groundwater reserves).
Griffis said it's hard to replicate nature in a greenhouse, but repeated experiments under controlled conditions can provide valuable insights. "It allows us to think about different cropping or rotation strategies," he said. "And perhaps in the long term, plant breeders can come up with varieties that can better adapt or take advantage of these changing climate conditions."
Another advantage to greenhouses is that researchers can grow three crops of corn each year instead of one, and they're using special LED lights to mimic summer sunlight for corn grown during the winter.
Researchers also are preparing six additional containers in an adjacent greenhouse that will each be enclosed. That will enable them to control the temperatures not just of the room, but the air temperature and carbon dioxide concentrations surrounding each cluster of plants and measuring what happens as they grow. One future experiment will dose the plants with elevated levels of carbon dioxide to measure how they behave, Griffis said.
"We'll be managing things like carbon uptake by the plants and carbon released by the plants to understand dynamically their photosynthetic rates and how they're changing over time," he said.
Predictions about the potential effects of climate change on agriculture need to be validated, Griffis said, and it's easier to do that in a greenhouse than in the field. "What we're hoping to do is turn up the temperature to a plausible future projection and learn what happens to corn yields," he said.