U.S. farmers this spring will plant the largest corn crop since 1944, growing supplies and driving down prices for most field crops, the U.S. Agriculture Department Chief Economist Joseph Glauber said Thursday.

The U.S. farm economy has been booming, enjoying strong prices and record returns last year. Glauber expects a slight pullback in 2012 as supplies grow, prices soften and demand cools. Still, he projected farm income for the year will be the second highest on record and crop prices will remain above historic levels.

"Prospects for U.S. agriculture continue to be strong," said Glauber, speaking here at the department's closely-watched annual outlook conference.

He expects U.S. farmers to plant 94 million acres of corn and 75 million acres of soybeans for harvest in the upcoming crop year, which runs from September 2012 to August 2013.

The corn projection was identical to the department's baseline forecast issued this month, but an increase from plantings last spring. Farmers sowed 91.9 million acres of corn in 2011. The projection for soy plantings was up from a baseline forecast of 74 million acres and even with plantings a year ago.

Recent high corn prices have made farmers more likely to plant corn instead of soybeans, according to analysts. The baseline projections to which Thursday's projection are often compared were compiled in November as part of the government's budget process.

Glauber's planting estimates largely met expectations with futures prices for corn and soybeans largely unchanged in morning trading at the Chicago Board of Trade. Still, shares of some farm suppliers, such as equipment makers Deere & Co. (DE) and Agco Corp. (AGCO), came under some selling pressure.

Glauber in his remarks forecast an 11.5% decrease from 2011 in income from farming, giving growers less money to spend on a range of products from tractors to fertilizer.

As for prices, the economist said average corn prices are likely to be around $5.00 a bushel in 2012-13, down nearly 20% from the previous year. Soybean prices are projected to fall 2% to $11.50 a bushel in 2012-13.

Helping to pressure prices is a weaker outlook for exports compared with a year ago and softening of corn demand by ethanol makers.

Total U.S. agricultural exports are likely to be $131 billion in the 2012 fiscal year, the second-highest on record behind 2011, as higher global crop production brings down prices and export volumes, Glauber said.

He added exports to China are likely to fall 15% due to concentration of trade in bulk commodities like soybeans and cotton.

Glauber said corn use for ethanol is likely to continue its slide. The amount of corn that went into ethanol in the 2011-12 marketing year fell to 5 billion bushels from 5.021 billion in 2010-11. The figure is likely to fall by another 50 million bushels more to 4.95 billion bushels in 2012-13.

The rapid rise of ethanol production in the U.S. over the past several years has come to a halt. The expiration of U.S. ethanol subsidies on Dec. 31, 2011 could limit production of the fuel this year to the 13.2 billion gallons that is required by Congress under the U.S. renewable fuel standard, if producers can't sell at attractive prices without the subsidies, Glauber said.