(Updates with closing prices, adds details, new analyst quote)
By Mark Weinraub
CHICAGO, Aug 17 (Reuters) - U.S. soybean futures rose to their highest in nearly four weeks on Wednesday on strong demand from China, the world's top buyer of the oilseed, traders said.
Corn and wheat futures posted mild gains on a round of short-covering. It was corn's fourth positive close in a row.
"We had some short-covering, got a little bit of a technical bounce," said Karl Setzer, market analyst at MaxYield Cooperative. "A lot of little things added up."
A global glut of wheat and expectations for a record corn harvest in the United States quelled buying in the grains. The upcoming U.S. soybean harvest also has been forecast as the biggest on record, but a recent spate of export activity underpinned the market.
The U.S. Agriculture Department said on Wednesday morning that private exporters reported the sale of 381,000 tonnes of soybeans to China for delivery during the 2016/17 marketing year.
The USDA also said that exporters reported the sale of 129,000 tonnes of soybeans to unknown destinations, correcting an Aug. 4 announcement that said corn was the commodity sold in the deal.
"Soybeans are providing at least a little lift to the grain market today, with concerns over a big crop muted by strong demand," Bryce Knorr, senior grain market analyst at Farm Futures, said in a note.
Chicago Board of Trade soybean futures for November delivery were up 8-3/4 cents at $10.16 a bushel. Prices peaked at $10.17-1/4 a bushel, the highest since July 21.
"There is market talk that U.S. soybean shipments to China in August will reach a hefty 1.8 million tonnes, which along with big shipments from Argentina and Brazil, could bring shipments to China in August to a massive 5 million tonnes," a European trader said. "China's economic slowdown is not braking soybean imports."
Spillover strength from a 1.7 percent gain in soyoil futures , which have rallied to a four-month high on the back of surging palm oil prices, lent additional support to soybeans. Soyoil futures have risen for six straight sessions.
CBOT September soft red winter wheat was up 2-1/2 cents at $4.26 a bushel. Higher-protein K.C. hard red winter wheat and MGEX spring wheat posted bigger increases.
CBOT December corn futures were 2-1/2 cents higher at $3.39-3/4 a bushel. Corn hit its highest since Aug. 1 and closed just below its session peak of $3.40 a bushel. (Additional reporting by Naveen Thukral in Singapore and Michael Hogan in Hamburg; Editing by Jeffrey Benkoe and Diane Craft)