Growing Season

Earlier planting-not climate-may be boosting corn yields.

How much difference can two weeks make? For corn growers in the northern United States, plenty. New research is finding that a two-week extension of the corn growing season is likely a significant factor driving up U.S. corn yields during the past 30 years.
Chris Kucharik, a scientist with UW-Madison’s Nelson Institute for Environmental Studies, set out to explain why Midwest corn growers produce three times more corn today than they did a half-century ago. After modeling the influence of several factors, including planting dates and climate change, he determined that earlier plantings account for 20 to 50 percent of the yield gains seen since 1979.
“What I found was that while climate probably has contributed in a small way to the yield trend, the overwhelming contribution has been from this land management change,” says Kucharik, an expert on climate and agriculture with the Nelson Institute’s Center for Sustainability and the Global Environment.
It also doesn’t appear to be the case that farmers are planting earlier because of warming temperatures. Instead, Kucharik says new corn seeds are engineered to endure the colder and wetter soils of early spring, which has allowed northern corn growers to adopt hybrids with a longer growing season.
“Before we jump to conclusions about the impacts of climate change on agriculture, we really need to consider subtle management changes that are taking place and will likely take place in the future,” says Kucharik. “Anytime you deal with a system that’s being managed by people, it makes for a more complicated story.”