U.S. wheat ended nearly flat on Wednesday as concerns about dry conditions underpinned the market, but corn and soybeans slid in choppy trading the day before the U.S. Thanksgiving holiday.
Trading was light ahead of the break, leaving markets vulnerable to sudden changes.
"In a thin market like this you can push it down a few cents, and then get to some technical or psychological level and... two hours from now see it up a few cents," said analyst Bill Nelson of Doane Advisory Services.
Chicago Board of Trade (CBOT) December wheat rose 1/4 cent to $8.45-1/4 per bushel, shrugging off comments by Russia's deputy agriculture minister that Russian grain exports could reach 15.5 million tonnes in the current crop season (all figures US$). Some back months weakened slightly.
Dry weather and record-setting high temperatures are maintaining "severe stress" on hard red winter wheat from South Dakota to Texas, the U.S. Department of Agriculture (USDA) said Wednesday.
"I'm surprised we're not getting more publicity out of the poor wheat conditions," said Jason Roose, vice-president at U.S. Commodities.
USDA said Monday its rating of the winter wheat crop fell to 34 per cent good-to-excellent, below analysts' expectations, due to persistent dry conditions in the U.S. Plains.
Chicago December corn lost 0.3 per cent, or 2-1/4 cents, at $7.41 a bushel, snapping a three-day winning streak on profit-taking and slowing demand for ethanol production.
After recent disappointing weekly corn export data from USDA, more poor results are expected Friday, as U.S. corn remains too pricey to be competitive, Roose said.
"You have historically very high prices, and I think even the best merchandisers in the country are saying, 'How long can we keep these strong premiums?'"
Firm U.S. cash markets and tight supplies underpinned corn prices, said Rabobank analyst Erin FitzPatrick.
Chicago January soybeans lost 0.3 per cent, or 4-1/2 cents, to $14.08-1/4 a bushel, on technical selling.
Traders were also digesting contradictory demand signals from China during the past week.
Private exporters reported the sale of 120,000 tonnes of U.S. soybeans to China for delivery during the 2012-13 marketing year, according to USDA on Wednesday.
China, the world's top soy importer, is expected to step up purchases from the overseas market with the government halting the sale of state reserves. Just last week, however, China cancelled orders for 600,000 tonnes of U.S. soybeans, sending soybean prices to a five-month low.
The South American weather forecast appeared slightly supportive for soybean and corn prices, with Argentina looking wetter and southern Brazil drier in the longer term, said Dan Cekander, director of grain market analysis for Newedge USA.
The shorter-term outlook for southern Brazil's dry soybean farms is more favorable, with rain expected by the weekend and into next week, weather forecaster Somar said on Wednesday. That would help kick-start germination of the newly seeded crop.
Hamburg-based oilseed analysts Oil World on Tuesday cut their forecasts for 2013 soybean harvests in Argentina and Brazil by a combined 3 million tonnes because unfavourable weather disrupted sowing.
-- Rod Nickel writes for Reuters from Winnipeg. Additional reporting for Reuters by Tom Polansek in Chicago, Michael Hogan in Hamburg and Naveen Thukral in Singapore.