(Recasts, updates with U.S. trading, adds new analyst quote, changes byline, dateline; previous HAMBURG)
By Mark Weinraub
CHICAGO, May 2 (Reuters) - U.S. soybean futures fell on Wednesday on concerns about decreased export demand from China as well as rising expectations for a bumper crop in Brazil, traders said.
Wheat futures were mixed. Soft red winter wheat offerings held steady near a nine-month top after a rally on Tuesday, while hard red winter wheat contracts rose due to worries about the drought-stressed crop in the U.S. Plains.
Corn futures were close to unchanged, underpinned by the slow start to planting in the U.S. Midwest.
The United States is sending a top-level trade delegation to China this week, but the market was discounting hopes of an agreement between the two countries.
"Most of the China watchers do not think they are going to come up with any breakthroughs," said Jim Gerlach, president of A/C Trading. "There is some nervousness in the soybean market."
At 10:34 a.m. CDT (1534 GMT), Chicago Board of Trade July soybean futures were down 4-1/2 cents at $10.48-3/4 a bushel.
U.S. soybean export sales to China have come to a halt, the chief executive of agricultural merchant Bunge Ltd said on Wednesday, over mounting trade tensions between the world's top two economies.
Additionally, INTL FCStone raised its estimate of soybean production in Brazil, the top supplier to China, to 117.0 million tonnes.
CBOT July soft red winter wheat futures were unchanged at $5.29-1/4 a bushel while K.C. July hard red winter wheat was up 4-1/4 cents at $5.57-1/4 a bushel.
The most-active K.C. hard red winter wheat contract peaked at $5.59-3/4 a bushel, its highest since July 11.
Yield prospects for hard red winter wheat in north Kansas were estimated at 38.2 bushels per acre (bpa), said crop scouts on the first day of the Wheat Quality Council's annual tour of the state. That is down from the tour's 2017 average yield of 43 bpa and the five-year average of about 42 bpa.
"First results of the crop tour are not positive," said Matt Ammermann, commodity risk manager with INTL FCStone. "There is also concern about dryness in Black Sea and Australia, so there is lots of dryness talk."
CBOT July corn was flat at $4.05-3/4 a bushel.
"For U.S. plantings, there is a lot of focus on the date May 15 as an important deadline for U.S. corn to be sown, Ammermann said. "Corn sown after May 15 could have lower yields." (Additional Reporting by Michael Hogan in Hamburg; editing by David Evans and Jonathan Oatis)