GRAINS-Corn falls ahead of US crop estimate; wheat and soybeans firm

By Michael Hogan

HAMBURG, Sept 8 (Reuters) - Chicago corn futures fell on Monday as traders awaited U.S. government harvest estimates later this week, with a record U.S. crop expected.

A weaker dollar, making U.S. supplies cheaper in export markets, underpinned grains and soybeans. USD/

Chicago Board of Trade most-active corn Cv1 was down 0.4% at $4.16-1/4 per bushel by 1158 GMT.

Wheat Wv1 rose 0.1% to $5.20-1/2 a bushel, soybeans Sv1 rose 0.1% to $10.28-1/4 a bushel.

Dealers were positioning ahead of world supply and demand reports from the U.S. Department of Agriculture on Friday, including U.S. corn and soybean harvests.

Matt Ammermann, commodity risk manager at StoneX, said corn is facing weakness due to expectations the reports will confirm a record U.S. corn harvest.

"Dryness in August may mean the U.S. corn crop may not be as large as forecast earlier, but on the bottom line it’s still likely to be a record, which is bearish," he said.

“Soybeans are supported by some belief the USDA may not be as optimistic on U.S. crop yields as previously."

However, a lack of Chinese buying of U.S. soybeans remains a bearish factor, with no substantive news from U.S./China trade talks, he said.

"The likelihood of Chinese buying of U.S. soybeans this season is declining as the weeks go by and the trade talks continue.”

Last week, S&P Global forecast U.S. corn and soybean production above the USDA's August outlook. Other private forecasts last week projected yields and production below the USDA.

Wheat was slightly firmer as the dollar softened, Ammermann said, but he added the market retained a bearish tone, with plentiful supply to export markets.

“Some support comes from Black Sea cash wheat prices, especially Russian, which have been falling but pretty moderately, with farmers dissatisfied with current low prices,” he said.