Freight on the lower Ohio River was under additional pressure following the reopening of the lock and dam in Belleville, Ohio, which freed up numerous stranded barges.
Traders said barge freight on the lower Ohio River fell 30 percentage points, adding to a 20-point drop on Tuesday.
Corn basis offers were steady to lower, weighed by a lack of fresh export interest, traders said.
Prices in the CIF barge market were weighed by improving conditions on the Ohio and Illinois rivers, where high water had slowed barge traffic in recent weeks.
Traders said there was no Chinese demand for US soyabeans, but added that there was talk of processors from China buying one to two cargoes from Brazil.
There was also talk of China buying soyabeans from Argentina, whose farmers are still holding on to large amounts of supplies harvested last year, the traders said.
"They sold some beans to China after a pick up in farmer selling recently," a trader said, adding that another round of farmer selling could result in more export sales.
Hard and soft red winter wheat basis offers were steady, with both markets lacking fresh export demand.
Both markets were quiet ahead of Thursday's announcement of wheat export subsidies to be doled out by the European Union. Traders have speculated anywhere from 3 to 11 euros ($4-$14).
Traders said the wheat market remained hobbled by delays in railcar deliveries, sometimes up to 30 days.