* Corn, soy areas slightly above expectations
* Soy area 3 pct larger than March estimate
* Largest corn area since 1937, 3rd largest soy
* Spring, durum wheat below expectations
* Corn stocks slightly below trade estimate (Adds details)
By Charles Abbott
WASHINGTON, June 29 (Reuters) - U.S. farmers planted slightly more corn and 3 percent more soybeans than they had initially planned, the government said Friday, but drought in the heartland jeopardized the harvest in a year when bumper crops are needed.
The Agriculture Department said growers planted the largest amount of corn in 75 years, and the third-largest amount of soybeans on record. The plantings were slightly larger than traders had expected.
"None of the numbers were dramatically different than the trade expected and we can get back to trading the weather," said Rich Nelson, an analyst at Allendale Inc.
Ordinarily, large plantings would be a virtual guarantee of a mammoth crop.
But the crop is threatened by a searing drought stretching from the central U.S. Plains to the eastern Corn Belt, with little relief in sight as the corn crop enters the crucial pollination stage.
In a tacit recognition of the drought, USDA said 8 percent of corn land would not be harvested, up 1 percentage point from a projection made two weeks ago. A record corn crop was still within reach, but hot and dry weather already reduced the harvest by 1 billion bushels, according to traders' estimates.
USDA's projections of plantings were based on a survey of 70,000 growers. It said wheat plantings were up slightly from its March estimate, but sowings of durum and spring wheat were below expectations.
Overall, corn, soybeans and wheat plantings were up marginally from USDA's March estimate while cotton was down 4 percent. Compared to last year, corn plantings are 5 percent larger, soybeans up 1 percent, wheat up 3 percent and cotton down 14 percent.
"Planted area is up in most states compared to last year due to expectations of better net returns in 2012 compared to other commodities," said USDA in referring to corn. It said the planted corn area set records in six states.
In a separate report, USDA said the corn stockpile was 3.15 billion bushels on June 1, the smallest amount since 2004 for this time of the year. That was 0.7 percent less than traders had expected.
The corn stockpile was expected to the smallest in 16 years by the time the fall harvest begins.
USDA's figures for soybean and wheat stocks were slightly larger than traders had expected.
(Reporting By Charles Abbott; Editing by John Picinich)