(Rewrites after closing, adds analyst quote)
By Mark Weinraub
CHICAGO, Sept 14 (Reuters) - U.S. wheat and corn futures firmed slightly on Wednesday, supported by a round of bargain buying, traders said.
Wheat received additional support from a weakening dollar and hopes that export demand for U.S. supplies will perk up in the coming weeks amid a production shortfall in Europe.
Export demand also provided underlying support to soybeans, but the oilseed closed lower on the expectations for a record harvest that have anchored prices for weeks.
"The U.S. export program had some positive news hit the wires overnight, with France reinforcing their lack of available wheat for export and Argentina waffling on soy export tax cuts, but the beginning of the massive 2016 grain harvest will continue to weigh heavily on the market," Matt Zeller, director of market information at INTL FCStone, said in a note to clients.
Chicago Board of Trade December soft red winter wheat futures rose 2 cents to close at $4.03 a bushel and CBOT December corn rose 1-3/4 cents to $3.31-3/4 a bushel.
France, Europe's largest grain producer, harvested 28.5 million tonnes of soft wheat this year, down from a record 40.9 million in 2015, FranceAgriMer said on Wednesday after adverse spring weather hampered crop development.
CBOT November soybeans dropped 1-1/4 cents to $9.42-3/4 a bushel.
Uncertainty about Argentina's plans for soybean exports limited the decline in soy futures.
Argentina's government is mulling postponing a tax cut planned for next year on soy exports, cabinet chief Marcos Pena said on Tuesday, as a recession in Latin America's third largest economy eats into fiscal revenue.
Markets slumped earlier this week after the U.S. Department of Agriculture increased its estimate of a record-large U.S. soybean yield by more than expected. The USDA also forecast a record-large U.S. corn crop this year. (Additional reporting by Michael Hogan in Hamburg and Naveen Thukral in Singapore, editing by W Simon and Grant McCool)