GRAINS-Wheat hits one-month low on big supply, acreage forecast

(Rewrites throughout, adds quote, updates prices, changes byline, changes dateline from HAMBURG)

CHICAGO, Jan 16 (Reuters) - U.S. wheat futures fell to a one-month low on Tuesday, pressured by ample global grain supplies and a government forecast on Friday that said U.S. farmers planted more winter wheat this season than had been expected.

Soybeans climbed to a one-week high on short-covering and concerns that dry conditions in Argentina could trim yields in the world's No. 3 supplier. Corn was flat, with values capped by ample supplies.

Grain markets were still responding to Friday's U.S. Department of Agriculture crop supply and demand reports. Markets had been closed on Monday for the Martin Luther King Jr. Day holiday in the United States.

"We've not only got an ample world supply of wheat but a larger prospective domestic supply than we were expecting. That weighed on the market on Friday and that's spilling into today's trade," said Brian Basting, analyst with Advance Trading.

Wheat slumped almost 3 percent on Friday after the USDA estimated 2018 U.S. winter wheat plantings at 32.608 million acres, above analyst expectations for 30.1 million to 32 million acres.

Chicago Board of Trade March soft red winter wheat fell 4 cents to $4.16-1/2 per bushel by 12:11 p.m. CST (1811 GMT) after earlier hitting a low of $4.13-1/4, the lowest since Dec. 13.

U.S. wheat was not among the offers in a tender by top importer Egypt, which ultimately bought 295,000 tonnes of Russian wheat on Tuesday.

Soybeans edged higher amid worries about a dry start to Argentina's growing season and after weekend rains that were lighter than expected in some areas.

Strong U.S. domestic demand also supported soybeans after the National Oilseed Processors Association reported a record-large December soy crush of 166.382 million bushels among its members.

But gains in soybeans were capped by widespread rains in Brazil over the weekend, which fueled speculation that the world's largest exporter could harvest a larger-than-expected crop this season. Brazil's bumper crop could create headwinds for U.S. soybean exports.

The USDA on Friday raised its Brazilian soy crop forecast and lowered its U.S. export outlook.

CBOT March soybeans gained 5-1/2 cents to $9.66 a bushel. March corn rose 3/4 cent to $3.47 a bushel after hitting a contract low of $3.45-1/2 on Friday. (Additional reporting by Michael Hogan in Hamburg, Naveen Thukral in Singapore; editing by David Evans and Phil Berlowitz)