GRAINS-Corn, soy flat; exports support while large supplies weigh

(New throughout; updates prices, adds quotes, changes byline, dateline, previous SYDNEY/PARIS) CHICAGO, Aug 30 (Reuters) - U.S. corn futures fell to contract lows on Thursday on fund-driven selling tied to plentiful global supplies and expectations of a large Midwest harvest, analysts said. Soybeans followed the weak trend while wheat ended steady to lower. Chicago Board of Trade December corn settled down 3-1/4 cents at $3.45-1/2 per bushel after posting a contract low, its sixth in as many sessions, at $3.45. CBOT November soybeans ended down 4 cents at $9.33-1/4 a bushel. CBOT December wheat finished flat at $4.29-3/4 a bushel as deferred contracts drifted lower. Trend-following commodity funds were net sellers of 10,000 CBOT corn contracts and 3,000 soybean contracts, traders estimated. Corn posted the biggest decline on a percentage basis, pressured by expectations that the U.S. 2017 harvest will be large, if not as big as the record 2016 crop. The global grain pipeline is still absorbing massive South America harvests. "With all these supplies around the world, and the U.S. crop being just big enough, it's causing a lot of competition. It's a race (to determine) who is going to get the demand," said Don Roose, president of Iowa-based U.S. Commodities. Soybeans fell for a fourth straight session on technical selling and optimism about U.S. yield prospects. Forecasts called for generally benign Midwest crop weather, aside from a few dry areas, and a low likelihood of frost through mid-September, which should benefit maturing crops. "Generally below-normal temperatures are expected across the Midwest but freeze threats are relatively limited," MDA Weather Services said in a daily note to clients. Wheat ended steady in rangebound trade. The December contract held above a contract low set on Tuesday, a mildly supportive chart signal.

CBOT settlement prices:

Last Net Pct Volume

change change

CBOT wheat WZ7 429.75 0.00 0.0 57112 CBOT corn CZ7 345.50 -3.25 -0.9 229704 CBOT soybeans SX7 933.25 -4.00 -0.4 91752 CBOT soymeal SMZ7 297.40 -1.80 -0.6 35706 CBOT soyoil BOZ7 34.69 0.04 0.1 51342

NOTE: CBOT September 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 Colin Packham in Sydney and Sybille de La Hamaide in Paris; Editing by David Evans and Sandra Maler)