UPDATE 3-US soy, corn supplies seen scant; to boost prices

* U.S. soybean stockpile to dip below two-week supply

* Rainy Midwest spring to lower corn yield, harvest

* Soybean carry-over stocks smallest in 32 years

* Corn carry-over stocks in 2010 smallest in six years (Updates with comment from American Farm Bureau economist, paragraph 6)

By Charles Abbott

WASHINGTON, June 10 (Reuters) - U.S. livestock feeders, exporters and food makers will have less than a two-week supply of soybeans, barely enough to keep running, when the fall harvest begins, the government forecast on Wednesday.

Analysts said the corn market faces a similar squeeze in 2010, a ripple effect of a rainy spring that delayed planting and will reduce this year's corn harvest. The corn stockpile would drop to a four-week supply.

The tight supplies are forecast to boost farm gate prices. Producers would sell this year's corn crop for a record $4.30 a bushel at the farm gate, up 10 cents from the 2008 crop, said the U.S. Agriculture Department (USDA). It forecast a farm gate price for soybeans of $10 a bushel for 2008 and 2009 crops, 10 cents below the record set by the 2007 crop.

Soybean supplies will rebound, with a record crop of 3.195 billion bushels projected by USDA for this year. Corn is projected at 11.935 billion bushels, but the crop could be smaller if bad weather blocked farmers from planting corn. [ID:nDAT001263] [ID:nN10435355]

USDA's corn-crop projections assume plantings of 85 million acres. It will survey growers ahead of the Acreage report on June 30 to update plantings and project harvest area.

"Many market analysts are expecting a 3 million acre reduction in 2009 corn plantings, with nearly all of that acreage being shifted into soybeans, so concerns about acreage will continue to influence the market until the end of June," said Terry Francl, an American Farm Bureau Federation economist.

Corn and soybeans are widely used in livestock rations and in an array of foods, besides serving as raw materials for biofuels. They are among the largest U.S. farm exports too.

Jack Scoville, vice president of Price Futures Group, said soybean users face "a pretty tight situation" with the stockpile forecast to bottom out at 110 million bushels, the smallest "carry over" in 32 years.

In seven of the past 10 years, the soybean stockpile actually was larger than forecast, said Darrell Good, a University of Illinois agricultural economist. He said high prices will help ensure America "will not run out of soybeans prior to harvest of the 2009 crop."

A corn crop of 11.935 billion bushels would be the third largest on record. USDA projects usage of 12.460 billion bushels, which would reduce the stockpile by one-third, to a comparatively small 1.090 billion bushels next fall.

The forecasts of higher crop prices boosted Wall Street prices of farm suppliers and exporters while hitting meat processors, whose profits are hit by higher costs.

Fertilizer giants gained the most. Mosaic Co (MOS.N) rose $1.55 to close at $55.28 and Potash Corp (POT.N) rose $1.80 to close at $117.34. Crop processor Archer Daniels Midland Co (ADM.N) rose 55 cents to close at $28.80 and General Mills Inc (GIS.N) rose 12 cents to close at $54.53.

With tight supplies likely to boost the price of livestock feed, meat processors Tyson Foods Inc (TSN.N) fell 43 cents to close at $12.80 and Smithfield Foods (SFD.N) fell 42 cents to close at $11.74. Farm equipment maker Deere & Co (DE.N) fell 23 cents to close at $45.71 after an early surge to $46.93. (Reporting by Charles Abbott; Editing by David Gregorio)