Corn plunged Thursday after the government reported that inventories were higher than expected and that farmers intend to plant the most corn in almost 80 years.
Stocks of corn totaled 5.4 billion bushels March 1, the U.S. Agriculture Department said in its quarterly grain stocks report, exceeding analysts' forecasts. While inventories are down 10 percent from a year ago, following last year's drought, Thursday's estimate still exceeded the expectations of traders and analysts, said Mike Zuzolo, president of Global Commodities Analytics and Consulting.
The USDA's survey of prospective plantings also weighed on prices. Corn growers intend to plant 97.3 million acres of corn for 2013, a slight increase on last year and 6 percent higher than in 2011. That would represent the highest total area planted in the U.S. since 1936, when 102 million acres were planted.
"The USDA found a lot more supply than the market was expecting," said Zuzolo. Traders "are really having to price these reports in."
May corn tumbled 40 cents, or 5.4 percent, to $6.9525 a bushel, the biggest one day drop in more than nine months.
Wheat and soybeans also dropped sharply.
May wheat dropped 49 cents, or 6.7 percent, to $6.8775 a bushel. Soybeans for the same month fell 49 cents, or 3.4 percent, to $14.0475.
Most metals declined as well.
Copper for May delivery rose 4.15 cents to $3.4020 a pound. Gold for June delivery fell $10.30 to $1,596.9 an ounce.
Silver for May delivery fell 28.90 cents to $28.3230 an ounce. Palladium for June was unchanged at $768.25 an ounce. Platinum for April delivery fell $8.6 to $1,571.20 an ounce.
In energy trading, the price of oil edged higher, pushing the May contract up 65 cents, or 0.7 percent, to $97.23 a barrel.
Wholesale gasoline fell 1 cent to $3.1054 a gallon. Heating oil was unchanged at $2.9152 a gallon. Natural gas fell 4 cents to $4.024 per 1,000 cubic feet.