The most active corn contract for March delivery was down 3 cents, or 0.77 percent to close at 3.87 dollars per bushel. March wheat was down 8 cents, or 1.44 percent to settle at 5.4825 dollars per bushel. January soybeans were down 0.25 cent, or 0.03 percent to close at 9.285 dollars per bushel.
China and the United States agreed last week on the text of a phase one economic and trade agreement, which significantly pushed up CBOT crop futures, especially soybeans, in the past four straight sessions.
Profit taking on Wednesday dragged down CBOT prices, said market watchers.
Market participants are also awaiting a weekly export sales report to be released on Thursday by the U.S. Department of Agriculture.