(Updates U.S. market activity to close)
By Michael Hirtzer
CHICAGO, Sept 7 (Reuters) - U.S. corn, soybeans and wheat each rose 1 percent or more on Wednesday, lifted by short-covering linked to export demand prospects and expectations of bullish supply data due next week from the U.S. Department of Agriculture.
The USDA earlier said exporters sold 484,000 tonnes of U.S. soybeans to China and unknown destinations, and more such announcements could be forthcoming after China last week signed deals to buy nearly 4 million tonnes of U.S. soybeans.
Wheat traders were optimistic that cheap U.S. grain could be sold to Northern African destinations such as Algeria and Morocco, while top importer Egypt rejected a cargo of Romanian wheat because of strict quality specifications.
A steep decline in the dollar against a basket of currencies on Tuesday made U.S. goods more competitive in global markets, supporting grain and soy futures at the Chicago Board of Trade. The dollar reversed a portion of the decline on Wednesday while the Federal Reserve said the U.S. economy expanded at a modest pace in July and August.
"It's a lot of little things. Add it all up and you get some short-covering," EFG Group's Tom Fritz said of bullish factors that prompted gains.
Soybean and soymeal futures led the way higher, with most-active CBOT November soybean futures finishing up 15-3/4 cents to $9.75-1/2 per bushel, a 1-1/2-week high.
CBOT December corn gained 4-3/4 cents to $3.33-1/4 per bushel, and CBOT December wheat was 4-1/4 cents higher at $4.02-3/4 per bushel.
Paris milling wheat for September delivery sank to a contract low after news of the Egypt cargo rejection.
The USDA was widely expected to trim soybean ending stocks for the 2016/17 marketing season in the agency's monthly supply and demand report due on Monday. A Reuters poll of analysts ahead of the report was due later on Wednesday.
"Soybeans are seeing support from strong U.S. exports while at the same time the market assesses just how much of a record large size the U.S. harvest will reach," said Stefan Vogel, head of agricultural commodity markets research at Rabobank.
Additional reporting by Michael Hogan in Hamburg and Naveen Thukral in Singapore; Editing by Meredith Mazzilli and Steve Orlofsky