Ethanol production is forecast to double by the end of 2008 to more than 13 billion gallons. Demand for corn will continue to grow in the near term despite mammoth crops. A bushel of corn, the major feedstock for ethanol, yields 2.8 gallons of the renewable fuel.

Based on a survey of 88,000 growers in the first half of June, the Agriculture Department said farmers planted 92.9 million acres of corn this spring, the largest sowing since 1944 and 3 percent more than growers planned in March.

With normal weather and yields, the crop would top 12.8 billion bushels, 1 billion bushels larger than the record set in 2004. Some analysts, including David Driscoll of Citigroup, said more than 13 billion bushels may be harvested.

"It's just incredible," said USDA chief economist Keith Collins of the possible huge crop and the prospect of a larger corn stockpile. It meant "a little cushion" against bad weather, he said, and will "give livestock feeders some relief."

The corn stockpile could be roughly 500 million bushels larger than expected a month ago because of the upturn in corn plantings and a quarterly USDA report showing more corn was in warehouses than expected.

Some 3.4 billion bushels of this year's crop are forecast to be used for ethanol during the 2007/08 marketing year, up sharply from the 2.15 billion bushels being used from the 2006 crop.

Because of the sudden surge in demand for corn, USDA says the average farm-gate price for corn will run at record levels.

The high prices have resulted in less corn being fed to livestock over the past couple of years.

"Many farmers across the country shifted to planting more corn this year at the expense of soybeans," said USDA.

In Illinois and Iowa, the two leading corn and soybean states, growers cut soybean plantings by a total of 2.1 million acres from 2006.

Soybean plantings were pegged at 64.1 million acres, down 15 percent from the record set last year. Based on USDA's projected yields and estimates of harvest area, the soybean harvest would be 2.62 billion bushels, the smallest since 2003.

Wheat sowings were up 6.0 percent from last year at 60.5 million acres. The wheat harvest would reach 2.178 billion bushels based on harvested acreage of 52.484 million acres.