CHICAGO, May 11 (Reuters) - Chicago Board of Trade soybean futures rose on Thursday, snapping a three-session losing streak as a wave of bargain buying hit the market after prices sank to their lowest in 6-1/2 months, traders said.

Corn and wheat futures fell, with poor demand for U.S. supplies pushing prices toward lows hit earlier this month.

"Export sales were really bad," said Ted Seifried, chief market strategist for the Zaner Group. "They were within expectations but the expectations are so poor at this point."

The U.S. Agriculture Department said on Thursday morning that weekly export sales of corn totaled just 340,400 tonnes. Seifried said the total showed that end users could bypass U.S. supplies and wait for farmers in Brazil to harvest their crop.

Wheat export sales were 359,900 tonnes but traders focused on deals made around the globe that showed cheaper supplies were easy to come by for overseas buyers. Soybean export sales came in at 112,300 tonnes.

Chicago Board of Trade July soybean futures settled up 1-1/2 cents at $14.05-1/2 a bushel. Prices bottomed out at $13.85-1/4 a bushel, the lowest on a continuous basis for the most-active contract since Oct. 28.

CBOT July corn was down 11-3/4 cents at $5.82-1/4 a bushel and CBOT May soft red winter wheat was 14 cents lower at $6.27-1/4 a bushel.

The USDA will release its closely watched monthly World Agricultural Supply and Demand Estimates report on Friday, which will include forecasts for the 2023/24 marketing year for the first time.

Analysts were expecting the report to show that supplies of corn and soybeans will rise sharply in the coming year.

In the wheat market, talks over the Black Sea export deal remain center stage.

No deal was made to extend an agreement allowing for grain shipments from certain Ukraine ports on the Black Sea after discussions on Thursday between Ukraine, Russia, Turkey and the United Nations. (Reporting by Mark Weinraub; Additional reporting by Naveen Thukral in Singapore and Sybille de La Hamaide in Paris; Editing by Kirsten Donovan and Jonathan Oatis)