Low prices have attracted interest from exporters in US corn, with Chicago Board of Trade corn futures dropping to their lowest level in more than three years.
Strong export demand for US soybeans through December has tightened loading capacity at the Gulf, leaving little available for corn and other grains.
Also, strong basis levels at corn ethanol and soy processing plants in the US interior continue to support export premiums.
USDA said private exporters reported US soybean sales of 115,000 tonnes to China and 33,000 tonnes to unknown destinations for delivery in 2013-14.
Offers for soft red winter and hard red winter wheat were mostly unchanged.
Barge freight offers fell on Friday on the Mississippi River and Illinois River as heavy rains this week helped raise water levels, allowing barges to carry heavier loads.