UPDATE 2-U.S. corn, soy stocks steady, wheat stocks seen up -USDA

* USDA cuts Argentina soy crop by 3 pct, corn by 2 pct

* Traders expected deeper cuts in Argentina crops

* Brazil soy, corn steady, trade expected small cuts

(Adds additional comments, FAPRI estimates released)

WASHINGTON, March 8 (Reuters) - The U.S. Agriculture Department delivered few surprises in its monthly crop and world agricultural supply/demand reports, keeping U.S. corn and soybean supplies tight but raising global soybean and wheat stockpiles from a month ago.

Chicago Board of Trade wheat futures traded about 1 percent lower on the report, retesting levels last seen in mid-2012, with soybeans also lower and corn up 1 percent.

"This is really picking at a carcass to get much new out of this," said Jim Gerlach, president, A/C Trading.

The Argentine soybean and corn crops were both lowered by drought, USDA said. Projected soybean output was trimmed by 3 percent, to 51.5 million tonnes, and the corn crop by 2 percent, to 26.5 million tonnes. Analysts had expected slightly deeper cuts.

U.S. soybean end stocks were forecast for 125 million bushels, the smallest in nine years and a thin two-week supply when the new crop is ready for harvest - but unchanged on the month.

"(I was) a little surprised about USDA's decision to keep their numbers unchanged for soybeans. At a minimum, the trade was 100 percent certain of an adjustment on exports. The way this South American situation looks, we would expect further gains for U.S. sales," said Rich Nelson, director of research for Allendale Inc.

USDA analysts noted that although the U.S. soybean export sales and shipments pace has been brisk so far this season, they expect demand to drop off significantly once new-crop supplies from Brazil and Argentina hit the market.

Corn ending stocks were also forecast steady on the month at 632 million bushels, the smallest in 17 years and a bare three-week supply.

USDA cut its estimate of corn exports by 75 million bushels but said larger production of beef and poultry will increase demand for corn for feed.

Brazil was forecast to reap a record 83.5 million tonnes of soybeans. USDA stood by its forecast, although Brazil's forecasting agency lowered its estimate to 82.1 million tonnes this week.

USDA raised its forecast of world wheat ending stocks by 1 percent, or 1.5 million tonnes, to 178.2 million tonnes, due to larger stockpiles in India, the United States and Iran.

"World (wheat) supplies are growing. The market has priced in more wheat production coming, and that's definitely going to weigh on prices," said Sterling Smith, futures specialist at Citigroup.

The world wheat and soybean figures were larger than traders expected and the corn figure was a bit below expectations.

Global ending stocks for soybeans would be up slightly, to 60.2 million tonnes, while corn dipped by half a million tonnes, to 117.5 million tonnes, USDA said.

USDA will estimate spring plantings of U.S. corn, soybeans, wheat and nearly two dozen other crops on March 28. That annual report is based on a survey of more than 80,000 growers and is the first official measure of farmers' plans for this year.

USDA has projected record corn and soybean crops if weather and yields are normal, bouncing back from the severe 2012 drought. An influential U.S. think tank, FAPRI, made similar projections on Friday.

Also on March 28, USDA will report on the size of U.S. corn, soybean and wheat stockpiles as of March 1.

(Reporting By Charles Abbott; Editing by Ros Krasny, Alden Bentley and Nick Zieminski)