Soybeans and corn declined on Monday after falling equity markets and a credit crunch prompted investors to sell commodities to raise cash.
Soybean futures for May delivery fell by 3.7 percent, or 50 cents, to $13.0275 a bushel on the Chicago Board of Trade.
Soybean prices fell by 12 percent in the past two weeks.
Soybean-oil futures for May delivery declined by 3.3 percent or 2 cents, to 58.56 cents a pound, the lowest since Feb. 15.
Soybean-oil prices dropped by 12 percent in the past two weeks.
The most active contract for the oil almost doubled in the past 12 months, increasing as high as 72.69 cents on March 4, boosted by an increase in demand for bio-fuels and cooking oil.
Corn futures for May delivery fell by 3.6 percent or 20 cents to $5.3925 a bushel.
Corn prices increased by 38 percent last year, to $5.795 on March 11, boosted by high demand for grain based ethanol and livestock.
Wheat futures for May delivery dropped by 4.2 percent or 50.5 cents to $11.4775 a bushel.
Wheat had increased to $13.495 a bushel on Feb. 27 after global reserves were forecast to decline.
According to the U.S. Department of Agriculture, Russia was forecasted to harvest 5 percent more grain this year after producing 49.4 million tons in the year that ended May 31.