CHICAGO (Reuters) - Facing mounting bills and nervous creditors, U.S. farmers are beginning to sell off their crop stockpile - sometimes at a loss - and easing a months-long logjam prompted by the lowest grains prices in at least five years.

A farmer poses with a handful of corn kernels in DeWitt, Iowa July 12, 2012. REUTERS/Adrees Latif

Farmers now looking for cash to pay off debts and buy seeds for next season have been lured to sell by a four percent rise in corn futures over the past two weeks. That rise came after speculators with huge short positions were caught off guard when the U.S. Department of Agriculture (USDA) cut its corn and soybean harvest views on Jan. 12.

Speculators slashed their bearish bets in the CBOT corn market by more than 36,000 contracts in the week ended Jan. 19. They also cut net short holdings by nearly 28,000 contracts in soybeans, according to data released by the Commodity Futures Trading Commission on Friday.

In the eastern Corn Belt, tiny bumps in grain basis bids - the differential with futures that is paid for cash deliveries - have helped generate some selling interest in recent days.

Archer Daniels Midland Co ADM.N has lifted its spot corn basis bid at its massive Decatur, Illinois, processing plant by 6 cents per bushel over the past two weeks. Given gains in the futures market, cash prices there are up more than 20 cents a bushel.

But the amount of grain that moved into the supply chain is thought to be more of a trickle than a tsunami, say traders. And futures prices have not roared back, they say, in large part because of persistent concerns among grain traders over massive global stocks and tepid demand growth.

Soybean prices, up about 1 percent over the last two weeks, are facing headwinds as the harvest of another bumper South American crop ramps up.

Benchmark March futures for corn on the Chicago Board of Trade ended on Friday at $3.70-1/4 per bushel while March soybeans closed at $8.76-1/2 a bushel.

How much of the near-historic volumes of corn and soybeans stored on farms has been sold and moved into the supply chain in recent weeks is not known. Cash prices for these sales are also hard to pin down in a market without screen trading.

But traders are beginning to question the assumption that low prices had farmers hoarding as much grain as they thought.

“There’s still a significant amount of bushels to be sold, but not nearly as many as we had originally thought,” said Ted Seifried, chief market strategist at Zaner Ag Hedge.

About 61 percent of the country’s corn stockpile was held on farm on Dec. 1, the lowest since 2012, USDA data showed. Grain traders had expected that percentage to be closer to 69 or 70 percent.

Nevertheless, on-farm soybean stocks were still the second-highest level in more than seven decades, and on-farm corn stocks hit their third highest in nearly a century, USDA data shows.

U.S. farmers typically sell off much of their grain between Dec. 1 and March 1 to pay operational loans, fertilizer and seed purchases, taxes and land rent bills. But selling slowed when grain prices sharply dropped in the fourth quarter of 2015.

But now prices still remain lower. Ohio farmer Keith Truckor sold some grain late last year at just over $4, but is holding back some of his crop, hoping for a rally.

“Corn prices need to hit $4 for us to make a profit,” said Truckor, 53, who is storing the rest of the corn on his 1,400 acre family farm in northwest Ohio.