Grain prices were roiled early by a fresh recommendation from Goldman Sachs, which advised underweighting commodities for three to six months.
Trading was choppy through most of the day, although deferred corn contracts gained amid jitters over weather forecasts for the Corn Belt as farmers get ready to plant.
A US Department of Agriculture announcement of the sale of 165,000 tonnes of US soybeans to China for delivery in 2011/12 was supportive.
* A bumper crop of soy is expected in South America, although rain and thunderstorms through Brazil's Rio Grande do Sul crop region is further delaying the soybean harvest there.
Thunderstorms may develop over the weekend in Argentina, which would be unfavorable for maturing crops and harvest of summer crops.
Basis bids for corn and soybeans shipped by barge to the US Gulf Coast were steady early on Friday, capped by weak barge freight but underpinned by slow grain movement, traders said.