GRAINS-Exports push CBOT soy to 4-month high; corn, wheat firm

* S. American delays place premium on U.S. soybean supplies

* Weak dollar, rising crude provide additional support

* Wheat gains capped by world production prospects

(Updates prices, adds new analyst quote) CHICAGO, March 5 (Reuters) - Chicago Board of Trade soybean futures rose to their highest level in nearly four months in Tuesday morning trading, buoyed by strong overseas demand for U.S. supplies, traders said. Corn futures also rose, following the strength in soybeans. Wheat was firm, but rising expectations for a strong harvest in Australia as well as the U.S. Plains limited gains. Private exporters reported the sale of 675,000 tonnes of U.S. soybeans, including 330,000 tonnes for delivery during this marketing year, the U.S. Agriculture Department said on Tuesday morning. The old-crop sales, which traders said were likely purchased illustrated the difficulty that South American shippers are having in bringing the recently harvested crops to market.

"You have seen about a 55-day delay getting the boats loaded up down in Brazil," said Chris Robinson, a senior trader at Top Third Ag Marketing. "They are cancelling those sales down there and they are coming up to the Pacific Northwest and they are paying up for old-crop soybeans." Typically, soy supplies from Brazil and Argentina dominate the export market in March. But port delays have slowed the flow of beans leaving those countries, forcing importers to look to the United States to fill their needs despite higher prices. At 11:28 a.m. CST (1628 GMT), CBOT May soybeans were up 5-1/2 cents at $14.67-1/2 a bushel. The thinly traded March contract was up 7 cents at $14.97-1/2 a bushel after peaking at $15.11, the highest level for the spot contract since Nov. 8. "The logistical nightmare that is South America is overshadowing the needed early harvest and making the balance of a good South American crop and poor U.S. crop a moot point until it is cured," commodities brokerage INTL FCStone said in a note to clients. CBOT May corn was up 4-1/2 cents at $7.07-3/4 a bushel, while CBOT May wheat was 2-3/4 cents higher at $7.05-1/4 a bushel. Like soybeans, corn was strongest in old-crop months. "I think we are just still a little bit concerned about the tightness in the supply," said Frank Cholly, a senior commodities broker at RJO Futures. "Traders are comfortable with this $7 level. We have little dips and it comes right back." Gains in equities markets lent bullish support to risky assets such as grains and oilseeds. The Dow Jones Industrial Average surged to a record high on Tuesday, breaking through levels last seen in 2007. CME Group Inc on Tuesday said it would cut back its grain and oilseed trading hours on April 8. The exchange operator expanded the trading day in May 2012, but the move quickly came under sharp criticism, with many traders saying it reduced liquidity and made for a less efficient market.

EXPECTATIONS FOR WHEAT CROP ON RISE The gains in wheat were capped by the improved outlook for a large global crop this year. In the U.S. Plains, warmer temperatures this week in the Plains would melt much of the snowcover from a pair of big blizzards in late February, adding crop-friendly moisture to the drought-stricken hard red winter wheat region, said Andy Karst, meteorologist for World Weather Inc. USDA's National Agricultural Statistics Service said late on Monday that good-to-excellent ratings for wheat in Kansas, the biggest hard red winter producer, and in Oklahoma rose following the storms. Australia on Tuesday forecast wheat production in the 2013/14 marketing year would rise 13 percent from the previous year, boosted by increased planting and higher yields from better growing conditions. Wheat production there is expected to be 24.9 million tonnes, up from 22.077 million in the 2012/13 season, the Australian Bureau of Agriculture and Resource Economics and Sciences said. Prices at 11:30 a.m. CST (1730 GMT)

LAST NET PCT YTD CHG CHG CHG CBOT corn 730.50 7.50 1.0% 4.6% CBOT soy 1497.75 7.50 0.5% 5.6% CBOT meal 433.90 1.70 0.4% 3.2% CBOT soyoil 50.14 0.09 0.2% 2.0% CBOT wheat 696.25 0.25 0.0% -10.5% CBOT rice 1535.00 1.50 0.1% 3.3% EU wheat 246.50 -0.75 -0.3% -1.5%US crude 90.16 0.04 0.0% -1.8% Dow Jones 14,266 138 1.0% 8.9% Gold 1574.66 1.32 0.1% -6.0% Euro/dollar 1.3017 -0.0008 -0.1% -1.3% Dollar Index 82.2180 0.0230 0.0% 3.1% Baltic Freight 806 17 2.2% 15.3%

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 Sam Nelson in Chicago and Naveen Thukral in Singapore; Editing by John Wallace and Bob Burgdorfer)