GRAINS-U.S. soybeans firm, pull corn higher

* Soybeans top $15 on bull spreading, strong export demand

* Corn follows soy higher but U.S. weather weighs

* Wheat drops to lowest since March 3

(Recasts, adds new analyst quote, updates prices, changes byline, dateline) CHICAGO, June 2 (Reuters) - U.S. soybean futures rallied on Monday on signs of strong export demand that threatened to further deplete thin U.S. supplies, traders said. The gains in soybeans pulled corn higher, but wheat futures sagged to a three-month low on ample global stocks and lackluster demand. CBOT wheat has fallen for nine sessions in row. Tight U.S. soybean supplies, combined with expectations of a huge harvest this fall amid forecasts for good crop weather in the Midwest, led investors to add to bull spreads. The spreading pushed the front-month soybean contract above $15 a bushel while new-crop months were close to unchanged. Corn prices followed a similar pattern. The U.S. Agriculture Department will release its first ratings for the recently seeded corn crop on Monday afternoon. Analysts expected the USDA to show good-to-excellent ratings for corn at 70 percent.

"This weather continues to benefit most of the U.S. crop," Matt Zeller, director of market information at INTL FCStone, said in a note to clients. "Early-season prospects couldn't be shaping up much better." Soybean prices surged to session highs after the USDA said weekly export inspections of the oilseed were a better-than-expected 156,364 tonnes. The benchmark Chicago Board of Trade July soybean futures contract was up 13-3/4 cents at $15.07 a bushel at 11:35 a.m. CDT (1635 GMT). CBOT July corn rose 2-1/2 cents at $4.68-1/4 a bushel, and CBOT July wheat was 6 cents lower at $6.21-1/4 a bushel. The front month contract bottomed out at $6.16-1/4, its lowest since hitting $6.08-1/4 on March 3. Weekend rains in the southern U.S. Plains and forecasts for more precipitation this week may help heading and maturing hard red winter wheat crops in some areas. The improving U.S. picture has reinforced a bearish mood in the wheat market, with good crop conditions across Europe and promising sowing prospects in Australia and Argentina. Favorable weather in May has also brightened prospects for the 2014 grain harvest in Russia and Ukraine, easing risks related to the lack of financing available for sowing, analysts and traders said. Russia and Ukraine have already clinched a series of new-crop export sales deals, putting further pressure on U.S. prices. Prices at 11:37 a.m. CDT (1637 GMT)

LAST NET PCT YTD CHG CHG CHG CBOT corn 468.25 2.50 0.5% 11.0% CBOT soy 1506.25 13.00 0.9% 14.8% CBOT meal 507.40 7.20 1.4% 15.9% CBOT soyoil 38.48 -0.02 -0.1% -0.9% CBOT wheat 620.75 -6.50 -1.0% 2.6% CBOT rice 1487.00 -11.50 -0.8% -4.1% EU wheat 190.50 -1.00 -0.5% -8.9% US crude 102.25 -0.46 -0.5% 3.9% Dow Jones 16,735 18 0.1% 1.0% Gold 1243.79 -6.90 -0.6% 3.2% Euro/dollar 1.3590 -0.0040 -0.3% -0.5% Dollar Index 80.6690 0.3000 0.4% 0.8% Baltic Freight 934 0 0.0% -59.0%

In U.S. cents, benchmark contracts, except EU wheat (euros) and soymeal (dollars). CBOT wheat, corn and soybeans per bushel, rice per hundredweight, soymeal per ton and soyoil per lb.

(Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Jeffrey Benkoe)