(Updates with closing prices) CHICAGO, Oct 11 (Reuters) - U.S. corn and wheat futures fell to one-month lows on Wednesday, a day ahead of monthly U.S. Department of Agriculture reports that are expected to confirm big crops and plentiful global grain supplies, analysts said. Soybeans closed fractionally lower after a choppy session. Chicago Board of Trade December corn settled down 3-1/4 cents at $3.46 per bushel, December wheat ended down 2 cents at $4.33-1/4 a bushel, and November soybeans fell 3/4 cent at $9.65-1/4 a bushel. Corn dipped to $3.45-1/2 near the close, its lowest level since Sept. 12 and just above its contract low of $3.44-1/4. The market was anchored by plentiful supplies and ideas that the USDA will raise its estimate of the U.S. corn harvest in its supply/demand reports on Thursday. "The expectations for this report, with a higher yield in corn, have got us under pressure," said Ted Seifried, chief market strategist with Zaner Ag Hedge. Rains slowed the U.S. Midwest harvest in recent days. The USDA in a weekly crop progress report said the corn harvest was 22 percent complete, lagging the five-year average of 37 percent. The soybean harvest was 36 percent complete, behind the five-year average of 43 percent. The corn harvest was only 8 percent finished in Iowa, the top U.S. corn state, and 4 percent complete in Minnesota, the No. 4 producer. Yet the futures market seemed unconcerned. "We are way behind up here and it has people nervous. But eventually you get it harvested. It's more a function of what the size of the crop is going to be," said Mark Schultz, chief analyst at Minnesota-based Northstar Commodity Investment Co. Some analysts noted that the USDA's weekly crop condition ratings improved for both corn and soybeans, a possible sign of rising yield prospects. CBOT wheat fell on technical selling, with the December contract dipping to $4.29-3/4, its lowest level since Sept. 12. The CBOT and K.C. December wheat contracts settled roughly 10 cents above their respective contract lows. The USDA confirmed that private exporters in the last day sold 104,202 tonnes of U.S. hard red winter wheat and 150,000 tonnes of corn to Mexico. Exporters also sold 264,000 tonnes of soybeans to China and another 132,000 tonnes of soy to unknown destinations. "While this was in fact positive news, the fact that yearly sales trail expectations (is) limiting market response," MaxYield Cooperative analyst Karl Setzer wrote in a note.
CBOT settlement prices:
Net Pct Volume
Last change change
CBOT wheat WZ7 433.25 -2.00 -0.5 69235 CBOT corn CZ7 346.00 -3.25 -0.9 147560 CBOT soybeans SX7 965.25 -0.75 -0.1 137857 CBOT soymeal SMZ7 314.90 -1.30 -0.4 34066 CBOT soyoil BOZ7 33.15 0.04 0.1 37766
NOTE: CBOT December wheat, December corn and November soybeans shown in cents per bushel, December soymeal in dollars per short ton and December soyoil in cents per lb.
(Additional reporting by Naveen Thukral in Singapore; Editing