CHICAGO, May 2 (Xinhua) -- Chicago Board of Trade (CBOT) grains closed lower on Wednesday, with soybean futures falling nearly one percent on concerns about decreased export demand from China as well as rising expectations for a bumper crop in Brazil, traders said.

Corn futures were close to unchanged but closed in negative territory. The yellow grain was underpinned by the slow start to planting in the U.S. Midwest but traders were reluctant to push prices past the 9-1/2-month top hit during the session.

The most active corn contract for July delivery went down 0.75 cent, or 0.18 percent to close at 4.05 dollars per bushel. July wheat delivery fell 2.5 cents, or 0.47 percent to close at 5.2675 dollars per bushel. July soybean delivery dropped 10.25 cents, or 0.97 percent to close at 10.43 dollars per bushel.

As for international market, agriculture weather forecasts are concerning. There is no rain in sight for Australian wheat areas with winter grain seeding normally underway. Black Sea weather forecasts offer limited rain for the next 2 weeks with warm to hot temperatures this week and cooling next week.

And the winter Brazilian corn areas will be bone dry into mid-May. Finally, the other South American weather extreme is flooding rains for portions of Argentina. World crop production is in decline with European traders very focused on emerging Black Sea dryness.