Corn prices plunged Thursday after the government predicted corn production would set a record this summer.

The U.S. Agriculture Department forecast corn production at 14.8 billion bushels compared with 12.4 billion bushels a year ago. It also expects yields to reach a record 166 bushels per acre and corn stockpiles on hand this August to total 851 million bushels.

A mild spring and ample moisture allowed farmers to get an early start on planting this year. They are expected to plant 91.9 million acres in corn, the most since 1937. Many hoped to capitalize on prices that have been at or above $6 per bushel for much of the year because of smaller stockpiles and strong export demand.

The forecast was released at the beginning of the growing season. Many factors could affect the outcome, such as a hot, dry summer. Telvent DTN analyst John Sanow noted that corn production has fallen short of the government's May forecast in the last few years and said there is a small margin for error during the growing season.

Corn for July delivery fell 19.75 cents, or 3.3 percent, to finish at $5.875 per bushel. That's the lowest since Dec. 16 when corn ended at $5.83 per bushel.

July wheat rose 1.25 cents to end at $6.0125 per bushel. July soybeans increased 25 cents to $14.5525 per bushel.

In other trading, cotton prices plummeted 4.7 percent after the government predicted record world stockpiles of 73.75 million bales by the end of August 2013. It also increased the estimate for stockpiles on hand in August to 66.88 million bales.

Penson/FCG analyst Sharon C. Johnson said that traders probably sold off contracts because of the ample stocks projected by the end of the 2013 season. Cotton for July delivery ended down 4 cents at 81.82 cents per pound.

Other commodities were mixed after the Labor Department said the number of people applying for U.S. unemployment benefits fell slightly last week to 367,000. That offered fresh evidence that U.S. hiring may increase in May, which took investors' minds off worries about Europe's debt crisis.

Gold for June delivery rose $1.30 to end at $1,595.50 an ounce. May silver fell 6.1 cents to $29.136 per ounce, May copper increased 2.2 cents to $3.6915 per pound, July platinum fell $5.40 to $1,493.80 an ounce and June palladium ended up $1.70 at $615.35 an ounce.

Benchmark oil rose 27 cents to finish at $97.08 per barrel on the New York Mercantile Exchange. Heating oil fell 1.57 cents to $2.9834 per gallon, gasoline futures dropped 1.39 cents to $3.0102 per gallon and natural gas rose 2.2 cents to $2.487 per 1,000 cubic feet.