Soybeans traded as high as $12.43 a bushel on June 26.
Todd Hultman, a grains and beans analyst at DTN, said the U.S. government estimated June 30 that U.S. growers have planted 84.8 million acres of soybeans, suggesting a record high crop of 3.8 billion bushels.
Hultman said the weather across growing regions in the U.S. Corn Belt has also been "very pleasant" in July, suggesting that the fall crop will be large.
Other crop futures also fell. Wheat lost half a penny to $5.56 a bushel and corn fell 2 cents to $4.04 a bushel.
Metals prices closed mixed.
August gold fell 50 cents to $1,316.50 an ounce, September silver was little changed at $21.01 an ounce and September copper edged down less than a penny to $3.26 a pound.
Palladium for October delivery rose $3.95 to $872.90 an ounce. The metal has risen 22 percent this year. September platinum rose 90 cents to $1,496.50 an ounce.
Energy prices closed broadly lower.
U.S. crude oil fell 13 cents to $103.40 a barrel in New York.
In other energy futures trading, wholesale gasoline fell 2 cents to $2.97 a gallon, heating oil lost 4 cents to $2.87 a gallon and natural gas fell 2 cents to $4.20 per 1,000 cubic feet. .