U.S. soybean futures fell early on Wednesday on concerns that China, the world's top purchaser of soybeans, may be forced to slow its imports amid signs of strain to the world's second-largest economy, traders said. Corn futures edged higher after dipping at the open, finding support amid technical buying as prices hit the 50-day moving average. Wheat futures fell but declines were limited, also due to technical buying at the 50-day moving average.

China's new export orders shrank in February by the most in eight months, a preliminary HSBC business survey shows, defying analysts' expectations of a pick up following the Lunar New Year holidays.

"One negative factor today was data out of China," said Carolyn Farndell, senior investment associate, at RBC Dain Rauscher. "The soybean market in particular is looking at larger Chinese exports so anything that would stand in the way of that is a negative. That is evidence of slowing in the economy."

Just last week, a Chinese delegation signed agreements with U.S. grain companies to buy 13.4 million tonnes of U.S. soybeans valued at $6.7 billion during the visit of China's Vice President Xi Jinping to the United States. Investors were staking out positions ahead of the U.S. Agriculture Department's annual Outlook conference on Thursday and Friday.

Traders also noted some profit-taking in soybeans following the market's run-up to its highest level since late September on Tuesday. The government is expected to project U.S. corn acreage in 2012 will be the largest since 1944, which could mean a record crop.

There is also speculation that large new soybean sales to China will encourage farmers to plant more beans. At 10:14 a.m. CST (1614 GMT), CBOT March soybean futures were down 7 cents at $12.64 a bushel.

CBOT March corn was up 1-1/2 cents at $6.31 a bushel. Corn futures hit a low of $6.25-3/4, less than 1 cent below the 50-day average, earlier in the session. CBOT March wheat was down 1/2 cent at $6.32-1/2 a bushel. Spillover pressure from the MGEX spring wheat market weighed on CBOT prices.

MGEX March spring wheat was down 3-1/2 cents at $8.13-1/4 a bushel. Significant snowfall is expected by the weekend in the dry areas of the U.S. spring wheat belt, which will provide a much-needed boost to soil moisture levels ahead of spring planting.

"This will be an improvement for them and there is another more active storm system for next week," said Don Keeney, meteorologist for MDA EarthSat Weather.

The dollar index, which measures the greenback's strength against a basket of currencies, rose 0.14 percent, making U.S.-dollar priced commodities more expensive for overseas buyers. But the main market focus remained on the upcoming USDA meeting.

"There seems to be continued positioning ahead of the USDA crop outlook this week rather than any specific new fundamental developments today," said Rabobank analyst Erin FitzPatrick.

"The U.S. corn acreage is likely to be very large, but it is still unclear what the soybean area will be."

(Additional reporting by Michael Hogan in Hamburg and Mayank Bhardwaj in New Delhi; Editing by Lisa Shumaker)