GRAINS-Soybeans hit 6-week low as Brazilian harvest looms; corn, wheat sag

By Julie Ingwersen

CHICAGO, Dec 12 (Reuters) - Chicago soybean futures fell to six-week lows on Friday as worries about slowing export demand for U.S. supplies and the looming harvest of a large Brazilian crop spurred a round of long liquidation, analysts said.

Corn and wheat futures followed the weak tone, pressured by rising global grain supplies.

Chicago Board of Trade January soybeans SF26 settled down 16-3/4 cents at $10.76-3/4 a bushel after dipping to $10.75-3/4, the contract's lowest since October 30.

CBOT March corn CH26 ended down 5-3/4 cents at $4.40-3/4 a bushel and March wheat WH26 finished down 4-1/4 cents at $5.29-1/4 per bushel.

Soybeans posted the biggest percentage declines as traders worried that the window for U.S. soybean exports was closing, with Brazilian farmers set to start harvesting a bumper crop in just a few weeks.

The U.S. Department of Agriculture (USDA) confirmed sales of 132,000 tons of U.S. soybeans to China on Friday, the latest in a series of bookings since late October. U.S. officials have said top global buyer China would purchase 12 million tons of the oilseed following a trade truce in late October.

But analysts are concerned that export demand for U.S. soy may soon dry up as South American supplies become available.

"Once China is done, who is there to buy U.S. beans, with the Brazilian discounts and the size of the crop down there?" asked Dan Basse, president of Chicago-based AgResource Co.

Brazilian crop agency Conab on Thursday lowered its forecast of the country's 2025-26 soybean crop to 177.12 million tons, still a record high, if confirmed.

Meanwhile, data from the U.S. Commodity Futures Trading Commission showed that managed commodity funds built a massive net long position in CBOT soybean futures by mid-November, leaving the market prone to bouts of long liquidation. The CFTC has been slowly releasing backdated commitments-of-traders reports from weeks when the U.S. government was shut down.

Corn futures fell on technical selling. The benchmark CBOT contract Cv1 was unable all week to break through overhead resistance at the $4.50 mark, anchored by ample global grain supplies.

A huge wheat harvest in Argentina threatens to compete with corn as a feed grain. The Rosario Grains Exchange raised its estimate of Argentina's 2025/26 wheat harvest to a record 27.7 million metric tons, from 24.5 million previously.

"Argentina is offering low-protein wheat under $200 a ton. They are pushing that wheat everywhere they can; it is competing with corn," Basse said.