River bids came under pressure as barge freight began to rise amid increased demand from shippers planning to haul grain in November, said an Iowa dealer.
"We'll probably see a short-term spike in the market," the dealer said.
Farmers were facing some of the lowest cash prices in years and were storing as much of their corn and soyabean crops as possible. Besides delivering on contracts negotiated when prices were higher, dealers were seeing little new business.
Farmers continued having trouble getting firm quotes on what nitrogen fertiliser would cost in the spring. Fertiliser prices have risen dramatically because of increased natural gas costs, a major component in making nitrogen fertiliser.
As a result, farmers were considering planting wheat, which requires less nitrogen fertiliser than corn, and soyabeans, which produce their own nitrogen.
Loan deficiency payments (LDPs) for soyabeans disappeared in several states on Tuesday and dropped to 2 cents in Iowa, Missouri and Nebraska.
LDPs for corn rose 1 to 2 cents on Tuesday and ranged from 44 to 49 cents - approaching highs reached in late September.
The US government offers LDPs to compensate for low cash prices. Farmers can claim LDPs without having to immediately sell their grain. Instead, they can store the crop and sell it later when prices rise in the cash market.
The US Department of Agriculture said late Monday that the soyabean harvest was 87 percent complete, compared with 76 percent a week ago and the five-year average of 79 percent.
USDA said the corn harvest was 65 percent complete compared with 49 percent a week ago and the five-year average of 62 percent.