U.S. corn futures are expected to start weaker Thursday after the government confirmed its projection for farmers to significantly expand plantings this spring.

Traders and analysts predict corn for May delivery, the most-active contract, will open 2 to 3 cents a bushel lower at the Chicago Board of Trade. In overnight electronic trading, the contract slipped 2 cents, or 0.3%, to $7.00 1/4 a bushel.

Futures may slip as the U.S. Department of Agriculture's Chief Economist Joe Glauber projected U.S. farmers will increase corn plantings 4.3% to 92 million acres for the 2011-12 marketing year, which covers the crop that will be sown this spring and harvested in the fall. The projection was identical to the USDA's baseline forecast issued Feb. 14, which pressured prices last week because it was larger than expected.

The forecast could ease supply concerns after futures rallied to 31-month highs earlier this week, partly to entice farmers to expand plantings to replenish tight supplies. If farmers plant 92 million acres of corn, they could reap a record crop of 13.75 billion bushels, which could add 300 million bushels to bare-bone reserves, according to Wisconsin-based risk management firm Stewart-Peterson.

"A projection of 92 million acres may put at least a near-term top in the market," the firm told clients in a note.

Still, large plantings do not ensure a large harvest because poor weather could hurt the crop. Users of corn are nervous because supplies are projected to come in at a 15-year low at the end of the 2010-11 marketing year on Aug. 31. Demand has stayed strong despite high prices.

Futures could feel additional pressure from selling by commodity funds, which have been exiting the grain markets this week as political turmoil in Libya raised concerns about the global economy, analysts said. Open interest in CBOT corn futures dropped 39,942 contracts Wednesday, according to preliminary data from the exchange.

The decline in open interest reflects that funds have been moving their money from the grains to energies and metals, where the potential for gains is considered to be greater because of the unrest in North Africa and the Middle East, according to AgResource Company, an agricultural consultancy in Chicago. Some market participants also may have been exiting the nearby March contract ahead of first notice day Monday, which is the first day that notices of intention to deliver actual commodities against futures-market positions can be received.

The "main market ingredients" for the moment are the protests in North Africa and the Middle East, said John Roach, president of Roach Ag Marketing, an agricultural advisory firm in Florida. Political and economic uncertainty is "scaring investors out of nearly all markets except gold and energies," he said.