(Recasts, updates prices, adds analyst comments; changes byline; dateline, previously HAMBURG/SINGAPORE)
By Michael Hirtzer
CHICAGO, Sept 7 (Reuters) - U.S. corn, soybeans and wheat each jumped about 1 percent on Wednesday, lifted by short-covering linked to export demand prospects and expectations for bullish supply data due next week from the U.S. Agriculture of Department.
The USDA earlier said exporters sold 484,000 tonnes of U.S. soybeans to China and unknown destinations.
Wheat traders were optimistic cheap U.S. grain could be sold into Northern African destinations such as Algeria and Morocco, while top importer Egypt rejected a cargo of Romanian wheat due to 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.
"It's a lot of little things. Add it all up and you get some short-covering," EFG Group Tom Fritz said of bullish factors that prompted gains.
Soybean and soymeal futures led the way higher, with most-active CBOT November soybean futures up 14-1/4 cents to $9.74 per bushel as of 12:17 p.m. CDT (1717 GMT), a 1-1/2-week high.
CBOT December corn gained 4-1/4 cents to $3.32-3/4 per bushel and CBOT December wheat was 3-3/4 cents higher at $4.02-1/4 per bushel.
Paris milling wheat for September delivery sank to a contract low after news of the Egypt cargo rejection.
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. Reuters poll of analysts ahead of the report were 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 Dale Hudson and Meredith Mazzilli