Barge freight bids on the Illinois River, lower Ohio River and Mississippi River at St. Louis were lower as the harvest neared completion, freight brokers said.
"The harvest is starting to wind down," a broker said. Freight was bid at 550 percent of tariff at St. Louis, 575 percent on the Illinois and 525 percent on the Ohio.
Hard and soft red winter wheat basis offers were mostly steady, supported by expectations of fresh sales.
A senior Iraqi trade official said the country would finalise details to buy 1 million tonnes of US wheat on Wednesday. It's worth about $170 million based on Tuesday's prices for HRW wheat, Iraq's wheat of choice.
"They are in negotiations," a trader said, referring to Iraq's Grain Board, which will purchase the wheat.
News of the imminent purchase helped to rally KCBT hard red winter wheat futures on Tuesday. It also helped to calm anxious traders waiting for word on the purchase.
On October 9, Iraq's Deputy Prime Minister Ahmad Chalabi said the country would buy 1 million tonnes of wheat from the United States in the next few days.
Corn basis offers were steady, supported by export demand from Asia and Latin America, traders said.
The traders were also keeping an eye on developments to the spread of bird flu from Asia to mainland Europe, adding that any mass culling of poultry could affect soyabean sales.
Top soyabean importer China reported another outbreak of the deadly H5N1 strain of bird flu among farm geese.