Chicago | Reuters — Chicago soybean futures approached a two-week high near US$10 a bushel Wednesday on technical buying ahead of the U.S. Thanksgiving holiday, analysts said.

Additional support stemmed from worries that the La Nina weather phenomenon, expected to emerge next month, could stress soy and corn crops in South America.

The La Nina weather effect, characterized by unusually cold ocean temperatures in the equatorial Pacific Ocean, is linked with floods and droughts.

Chicago Board of Trade January soybean futures settled up 8-1/4 cents at $9.97-1/4 per bushel after reaching $9.99-1/2, the contract’s highest since Nov. 9 (all figures US$).

CBOT December corn ended 1/4 cent higher at $3.45-1/4 a bushel while December wheat fell two cents at $4.22-3/4 a bushel.

U.S. markets will be closed on Thursday, with CBOT trade resuming Friday at 8:30 a.m. CT.

CBOT soybeans firmed on slow farmer selling now that the harvest of a record-large U.S. crop is virtually complete.

“Producers shut the bin door, and (cash) basis levels are trying to firm. There is just a lack of country movement out here,” said Don Roose, president of Iowa-based U.S. Commodities.

Worries about dryness expanding in Argentina’s crop belt lent support, although crop weather has been favourable in Brazil, the world’s top soybean exporter and No. 2 corn supplier.

Australia’s Bureau of Meteorology issued an alert for a La Nina weather event starting next month, saying the chance it would take place was triple the normal likelihood.

“It’s a reminder that we are in a La Nina year, and we know that that increases the odds for dry (conditions) in Argentina,” Roose said.

Corn closed fractionally higher after a choppy session. Chris Benson, owner of advisory The Ag Fix, said traders were taking profits on short positions ahead of the holiday.

“There’s money flow and short-covering across the board,” Benson said.

Wheat futures ended mixed, with front-month December losing ground to back months on spreads.

A decline in U.S. wheat crop conditions and market chatter about radioactive pollution reported in Russia encouraged some short-covering this week, but analysts said there was little impetus yet for a price rally in wheat.

The meteorological service in Russia, the world’s biggest wheat exporter, said on Tuesday it had measured pollution of a radioactive isotope at nearly 1,000 times normal levels in the Ural mountains.

“With net short positions at a high level, such reports may prompt short-term-oriented market participants to reshuffle their investments,” Commerzbank analysts said in a note.

— Julie Ingwersen is a commodities correspondent for Reuters in Chicago; additional reporting by Naveen Thukral in Singapore and Gus Trompiz in Paris.