Corn yields are hurting in the U.S. Midwest following a cold, wet spring slowing the crop's planting.

According to NBC News, corn plantings in the Midwest are at 19 percent this year compared to 28 percent last year at the same time, the U.S. Department of Agriculture found.

"What we're seeing over the last 15 to 20 years is very little (yield) growth in bad conditions, which tend to be very hot and/or dry, and much, much better growth during good conditions, which usually means a moderate amount of moisture and not too much extreme heat," Michael Roberts, an associate professor of environmental economics at the University of Hawaii - Manoa, told NBC News.

In a new study, published in the journal Science, researchers estimate crop yields will fall 15 to 30 percent over the next half-century. Study co-author Roderick Rejesus, a associate professor of agricultural and resource economics at North Carolina State University, said weather conditions will be a factor.

"Yield increases are getting smaller in bad conditions," Rejesus said in a press release. "Agronomic and genetic crop improvements over the years help a lot when growing conditions are good, but have little effect when growing conditions are poor, like during droughts."

Study lead author David Lobell, associate professor of environmental Earth system science at Stanford University, said agricultural research has been important for maximizing crop yields as the climate continues to change.

"The data clearly indicate that drought stress for corn and soy comes partly from low rain, but even more so from hot and dry air," he said in a press release. "Plants have to trade water to get carbon from the air to grow, and the terms of that trade become much less favorable when it's hot.

"Recent yield progress is overall a good news story. But because farm yields are improving fastest in favorable weather, the stakes for having such weather are rising. In other words, the negative impacts of hot and dry weather are rising at the same time that climate change is expected to bring more such weather."