CHICAGO, Nov 25 (Reuters) - Chicago wheat futures fell more than 3% on Wednesday and corn and soybean futures also slipped as traders booked profits after recent highs in all three markets, and ahead of Thursday's U.S. Thanksgiving holiday, analysts said.

Chicago Board of Trade March wheat futures settled down 21 cents at $5.96-1/2 a bushel, turning lower after rising to a three-week high of $6.22-3/4 in early moves.

Last month, the most-active CBOT wheat contract neared a six-year top at $6.38-1/4 as dry conditions in parts of Russia and the United States raised supply concerns.

But spring weather is typically more important in determining crop size, and in the absence of fresh supportive news, traders on Wednesday opted to book profits.

"Most of the wheat stuff is known. So there is not a lot of new news," said Don Roose, president of Iowa-based U.S. Commodities.

Also bearish, the Sovecon agriculture consultancy raised its forecast for Russia's 2020/21 wheat exports by 1.0 million tonnes, to 40.8 million tonnes, due to a higher crop estimate and a high pace of exports.

CBOT soybeans and corn closed lower. Benchmark soybean futures ended down 7-1/4 cents at $11.84 a bushel, retreating farther from Monday's four-year high of $12 a bushel, and corn settled down 5 cents at $4.27-1/2 a bushel.

Traders have been liquidating long positions in CBOT December corn, wheat, soymeal and soyoil futures ahead of first notice day for deliveries on Monday, Nov. 30.

Soybeans were pressured by signs that Chinese buyers may be balking at lofty U.S. prices. Some Chinese soybean importers and processors are looking to cancel U.S. cargoes for December and January shipment, after crushing margins collapsed following the CBOT rally, three trade sources said.

"The bottom line is more demand uncertainty going forward," Roose said.

However, soybean and corn futures had underlying support from worries about dry conditions in parts of Brazil and Argentina, where crops are still developing.

The CBOT will be closed on Thursday before reopening for a shortened session on Friday.

The U.S. Department of Agriculture is scheduled to release its weekly export sales report on Friday, a day later than normal, due to the holiday.

(Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Kirsten Donovan and Grant McCool)