Call it the ethanol effect.

Nationally, farmers are planting 15 percent more corn than a year ago, a total of 90.5 million acres, the most since the end of World War II.

Last year, the U.S. corn crop was valued at a record $33.8 billion. Corn climbed to a 10-year high of $4.50 a bushel on Feb. 26. The price has fallen since then amid concerns about overplanting, with corn for September delivery at $3.87 a bushel at Thursday's close on the Chicago Board of Trade.

The economics of farming mean that not everyone will be rolling in cash after the harvest. Farmers face higher fuel costs and higher feed costs for their livestock. Landowners have raised rents on farmland. And the higher cost of all that corn means ethanol plants may not be as profitable as in years past.

Some of this year's increase will mean fewer acres of other crops, including soybeans, wheat, barley, dry beans, sugar beets and flaxseed. Some crops still will be increased, including oats, sunflower, canola and hay plantings, according to the U.S. Department of Agriculture (USDA).

Despite farmers' corn intentions, the weather has reminded everyone that nothing in farming comes easy. A cold April and early rains have slowed farmers in southern Minnesota, and especially in Iowa, the heart of the nation's corn crop, where farmers had just 14 percent of the crop in the ground by last Sunday, compared with 58 percent in the ground by the same time last year, according to the USDA.