Corn futures ended sharply lower Thursday as traders worry about excess supplies of the grain.
Energy and metals prices also closed mostly lower.
Corn for May delivery fell 11.5 cents, or 1.8 percent, to $6.30 a bushel.
Wheat fell 2.5 cents to $6.94 a bushel and soybeans fell 8.25 cents to $13.72 a bushel.
Corn has been falling sharply since last week, when the Agriculture Department reported that the country's corn stocks were far higher than the market expected.
The U.S.D.A. said in its quarterly grains report that corn stocks totaled 5.4 billion bushels as of the beginning of March, and that farmers intend to plant the most corn in nearly 80 years. Corn closed at $7.33 a bushel March 27, the day before the report came out.
"The corn market has been in dire straits since the stocks report came out," said Sterling Smith, a vice president with Citibank Institutional Client Group.
Crude oil fell as an increase in the number of people seeking unemployment aid raised concerns about energy demand.
Oil fell $1.19 to finish at $93.26 a barrel. That makes a two-day drop of $3.93, or 4 percent.
Wholesale gasoline futures fell 2 cents to end at $2.90 a gallon and have dropped about 7 percent so far this week.
In other energy trading, heating oil fell 4 cents to end at $2.96 a gallon and natural gas rose 5 cents to finish at $3.95 per 1,000 cubic feet.
In metals trading:
— April gold fell $1 to $1,551.80 an ounce
— May silver fell 3 cents to $26.767 an ounce
— May copper rose 1.85 cents to $3.3515 a pound
— July platinum fell $24.10 to $1,517.80 an ounce
— June palladium fell $30 to $725.45 an ounce.