* Concerns over Chinese economic growth weigh on soybeans, corn
* Forecasts of much-needed rains in the U.S. grain belt
* Ukraine sea corridor hopes boosted by food aid cargo
CHICAGO, Aug 16 (Reuters) - Chicago corn, wheat and soybean futures fell for a second day on Tuesday, pressured by rainfall across parts of the U.S. Midwest, as well as economic uncertainty in China and grain shipments from war-torn Ukraine.
The most-active soybean contract on the Chicago Board of Trade (CBOT) fell 31-1/4 cents to $13.81 a bushel.
CBOT corn lost 18 cents to $6.10-1/4 a bushel, while CBOT wheat ended down 15 cents to $8.02-3/4 a bushel.
Soybeans extended Monday's losses after falling to their lowest in more than a week as an unexpected interest rate cut in China fanned worries about faltering growth in the world's biggest soy importer.
Forecasts for rain this week in dry western parts of the U.S. corn and soybean belt pressured markets, despite declining crop conditions last week as reported by the U.S. Department of Agriculture (USDA).
"The extended forecast looks wet and cool," said Ed Duggan, Senior Risk Management Specialist at Top Third Ag Marketing. "We ran it up on hot and dry, and now we’re backing off because of rain."
Weather concerns in Europe have also been tempered by showers and cooler temperatures this week that could provide late relief for corn crops.
Supply fears related to Russia's invasion of Ukraine have also been eased by initial grain shipments under a safe-passage agreement.
A first cargo of food aid bound for Africa since Russia's invasion left Ukraine on Tuesday, while the country's deputy infrastructure minister said it could export 3 million tonnes of grain from its ports in September.
"The flows out of Ukraine, even though they’re small … that’s bearish for the market," said Joe Davis, director of commodity sales at Futures International. (Reporting by Christopher Walljasper; Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore Editing by Marguerita Choy)
