GRAINS-Soybeans, corn, wheat weaken ahead of monthly crop report

* Soybeans, corn fall from six-month highs

* Traders squaring positions ahead of USDA supply-demand report

* Worries about Chinese economy weigh on grains

(Updates with U.S. trading, adds new analyst quote, byline, dateline) CHICAGO, March 10 (Reuters) - U.S. soybean futures fell early on Monday, pulling back from a six-month high as investors locked in profits ahead of a key U.S. government supply and demand report. Corn and wheat also weakened on position-squaring ahead of the report. Concerns about disappointing economic data out of China, a big buyer of both U.S. corn and soybeans, added further pressure to the market after the country reported an unexpected drop in exports during February. "The corn market is lower overnight on follow-through selling from weaker Chinese economic data," said Sterling Smith, futures specialist with Citigroup. There also was talk China was looking to back out of some deals to buy Brazilian soybeans. At 9:42 a.m. CDT (1442 GMT), Chicago Board of Trade May soybean futures were down 14-1/2 cents at $14.43-1/4 a bushel. CBOT May corn was down 3 cents at $4.86 a bushel and CBOT May soft red winter wheat was 2 cents lower at $6.52 a bushel. "It is more of a position squaring ahead of (the) USDA report as the market had obviously rallied very strongly over the past month and a half or so," said Luke Mathews, a commodities strategist at Commonwealth Bank of Australia, referring to corn futures. The U.S. Agriculture Department's monthly supply and demand report, which analysts expect to show a lowering of the U.S. soybean stocks due to a robust export pace, will be released at 11 a.m. CDT (1600 GMT). Export commitments for U.S. soybeans for the 2013/14 marketing year, which began on Sept. 1, have already surpassed USDA forecasts. USDA also will put out global crop production forecasts, including closely watched estimates for soybean and corn crops in Brazil and Argentina.

Prices at 9:44 a.m. CST (1444 GMT)

LAST NET PCT YTD CHG CHG CHG CBOT corn 479.50 -1.50 -0.3% 13.6% CBOT soy 1443.00 -14.50 -1.0% 9.9% CBOT meal 460.50 -4.50 -1.0% 5.2% CBOT soyoil 44.08 -0.01 0.0% 13.5% CBOT wheat 653.25 7.00 1.1% 7.9% CBOT rice .00 0.00 0.0% -100.0% EU wheat 212.00 -3.25 -1.5% 1.4% US crude 101.27 -1.31 -1.3% 2.9% Dow Jones 16,346 -107 -0.7% -1.4% Gold 1343.50 3.65 0.3% 11.5% Euro/dollar 1.3869 -0.0006 -0.1% 1.6% Dollar Index 79.7830 0.0640 0.1% -0.3% Baltic Freight 1562 19 1.2% -31.4%

In U.S. cents, benchmark contracts, except EU wheat (euros) and soymeal (dollars). CBOT wheat, corn and soybeans per bushel, rice per hundredweight, soymeal per ton and soyoil per lb.

(Additional reporting by Naveen Thukral in Singapore and Sybille de La Hamaide in Paris; Editing by Meredith Mazzilli)