* Soy plummets on record U.S. production forecast

* Corn acreage smaller than expected

* Wheat drops on Black Sea competition

CHICAGO, Aug 12 (Reuters) - Chicago soybeans took a nosedive on Monday to their lowest level since September 2020 as the U.S. Department of Agriculture released data showing a record production forecast for the crop.

Meanwhile, corn rose as the USDA saw smaller than expected acreage, and wheat fell on competition from Black Sea crops.

The Chicago Board of Trade's most active soybean contract ended down 16-1/2 cents to $9.86 a bushel and corn settled up 6-1/2 cents to $4.01-1/2 a bushel.

Wheat fell 5-3/4 cents to finish at $5.36-3/4 a bushel.

The USDA's monthly world agricultural supply and demand report forecast a record soybean crop at 4.589 billion bushels, surpassing analysts' already record expectations and prompting major losses.

"USDA is looking for a potential record crop, so the beans are down pretty hard," said Jack Scoville, vice president at Price Group.

Meanwhile, some analysts were taken aback by a lower-than-expected harvested acres forecast in corn.

"Apparently farmers, looking at low (grain) prices and high inputs, decided to plant less corn and more beans. That area up in Minnesota, Iowa and up there in the Northern Plains that had some excess water, they switched to some beans," said Jim Gerlach, president of A/C Trading.

In a separate report after markets closed, the USDA held its ratings of the soy and corn crops steady, besting analyst expectations that had seen a percentage point drop for both.

Wheat faced pressure from the disclosure of offers on Egypt's biggest ever wheat tender, highlighting the competitive pricing of Black Sea supplies.

However, Egypt's state grains buyer later said it bought only 280,000 metric tons of wheat, falling short of its target of 3.8 million. Egypt was unable to meet its target largely due to higher-than-expected prices in the tender, traders said.

Wheat's fall was limited by bad crop news from France and elsewhere in Europe.

France's 2024 soft wheat crop is expected to be 25% below last year's after relentless rain. (Reporting by Renee Hickman in Chicago; Addiitonal reporting by Naveen Thukral in Singapore and Michael Hogan in Hamburg; Editing by Will Dunham)