DES MOINES, Iowa - For months, Illinois farmer David Kellerman held out hope for rain, even as the worst drought in nearly 25 years spread across the country.
He finally gave up when the temperature hit 108 three days in a row. Corn won't develop kernels if it gets too warm during pollination, and Kellerman knew the empty cobs in the fields where he works would never fill out. Just after the Fourth of July, he and the neighbor he farms with took an extraordinary step: They cut down the entire crop and baled the withered plants to use as hay for their cattle.
Almost a third of the nation's corn crop has been damaged by heat and drought, and a number of farmers in the hardest hit areas of the Midwest have cut down their crops just midway through the growing season. But the nation could still see one of the largest harvests in U.S. history, thanks to new plant varieties developed to produce more corn per acre and better resist drought.
Kellerman said he was surprised his corn fared as well as it did, growing to a decent height even though there had been less than an inch of rain since mid-April. The dirt in the area where he farms near Du Bois, Ill., has the consistency of dust, but it wasn't until the extreme heat "fried" the plants, that he lost hope.
"Genetics are much better," he said. "Corn five years ago would never have lasted this long."
Corn production has been improving steadily for decades, the result of scientific advances going back to the introduction of the first commercial hybrid in 1923. Genetic engineering accelerated the process in recent years and allowed the development of some strains that borrow DNA from other species for pest resistance.
Corn farmers expected this to be a record year when they planted, sowing 96.4 million acres, the most since 1937. The U.S. Department of Agriculture predicted they would get 166 bushels per acre.
But after months with little or no rain and extreme heat in large portions of the Corn Belt, the USDA on Wednesday revised that estimate, saying it now expects farmers to average just 146 bushels per acre this year.
That would still be an improvement from a decade ago, when the average was about 129 bushels. Agriculture Secretary Tom Vilsack still expects the nation to produce the third-largest corn crop in American history, even as he announced disaster-relief measures for farmers, like Kellerman, who have lost everything.
"It is important to point out that improved seed technology and improved efficiencies on the farm have made it a little bit easier for some producers to get through a very, very difficult weather stretch," Vilsack said. "Our hope is rains come to the central part of the United States soon to be able to salvage what can be salvaged."
The drought stretches from parts of Ohio to California. The historic drought that gripped Texas and other parts of the Southwest last year was more severe, but this year's dry spell is notable for the sheer size of the affected land.
"To see something on this continental scale, where we're seeing such a large portion of the country in drought, you have to go back to 1988," said Brad Rippey, a USDA agricultural meteorologist.
That year, farmers saw corn yields, or the amount produced per acre, drop by nearly a third.
This year's loss, so far, is expected to be half that — one reason why people like Bill Gates believe better crop technology will be the key to feeding the world as the population grows and climate changes.
Jeff Schussler, a senior research manager for DuPont Pioneer, said the company's studies show corn hybrids today can produce 50 percent more bushels of corn per inch of water than those of 50 years ago. Working with genes that affect root and leaf development and plant reproduction, scientists also have created much more stable corn plants that can withstand a wider variety of climate conditions, he said.
"All these hybrids that have been produced in the last few years are built for drought tolerance so we have a little more hope that they will be able to withstand some of this heat, more so than they would have say 10 years ago," said Garry Niemeyer, who grows corn and soybeans in Auburn, Ill., and is president of the National Corn Growers Association.
He said plants have been developed with a larger root mass, which allows them to reach deeper for water and hold more in reserve. Certain varieties also are capable of rolling up their leaves to slow moisture loss.
"There's a lot of technology that goes into our corn crop," Niemeyer said.
Still, it's hard to say how the year will turn out with about half of the growing season to go.
Corn plants today withstand drought better than they did in 1988, but no variety exists that can produce significant yields without rain for six weeks and sustained temperatures above 100 degrees, said Tony Vyn, an agronomy professor at Purdue University.
"You get to the point where the water shortage is so severe that technology is not going to guarantee yield, even when you might have that expectation," he said. "My experience thus far is that drought-tolerant hybrids are no silver bullet."