Soybean contracts sank to their lowest price in almost four years after a government report bolstered expectations for ample supplies.
In a report out Friday, the U.S. Department of Agriculture estimates that this season's soybean harvest could reach a record 3.8 billion bushels, which is 165 million bushels higher than its estimate last month.
Soybeans sank 18 cents, or 1.6 percent, to $10.75 a bushel. That's the lowest settlement price for soybeans since October 2010, according to the data provider FactSet.
The USDA's report also projected big harvests and stockpiles of corn and wheat.
Corn slipped 8 cents, or 2 percent, to $3.85 a bushel, while wheat lost 23 cents, or 4.1 percent, to $5.26 a bushel.
In precious-metals trading, gold and silver fell as worries over Europe's banking system eased.
Gold for August delivery slipped $1.80 to settle at $1,337.40 an ounce, while silver for September lost 5 cents to $21.46 an ounce. Both metals ended the week with gains of more than 1 percent.
Industrial metals were mixed. Copper was unchanged at $3.27 a pound. Platinum fell $3.20 to $1,513.80 an ounce, and palladium rose $1.70 to $875.30 an ounce.
In oil and gas trading, the price of oil sank 2 percent Friday, the largest one-day drop since April, as Libya appeared poised to begin pumping more crude oil into the market.
Benchmark U.S. crude for August delivery fell $2.10 cents to close at $100.83 a barrel on the New York Mercantile Exchange. The price of crude oil has dropped $4.54 a barrel, or 4 percent, so far in July.
In other energy futures trading:
— Wholesale gasoline fell 5 cents to close at $2.91 a gallon.
— Heating oil fell 3 cents at $2.86 a gallon.
— Natural gas rose 3 cents to close at $4.15 per 1,000 cubic feet.