GRAINS-Soybeans firm on shrinking Argentine crop, brisk U.S. demand

* Soybeans rise for second day

* Wheat down again; U.S. rain relief, Black Sea crops weigh

* Corn pressured by wheat after 7-month top this week

(Updates with European trading, changes byline/dateline) PARIS/SINGAPORE, March 16 (Reuters) - Chicago soybeans rose for a second session on Friday as dwindling harvest prospects in drought-hit Argentina and stronger than expected U.S. crushing demand supported the oilseed market. Wheat fell, adding to Thursday's steep losses, as forecasts of rain in part of the U.S. Plains and good crop conditions in the Black Sea export zone kept attention on large global supplies. Corn edged lower, curbed by weaker wheat prices but underpinned by brisk U.S. exports and falling expectations for Argentina's crop. The Chicago Board of Trade most-active soybean futures were up 0.5 percent at $10.45-1/2 a bushel by the end of the overnight session. The CBOT wheat contract was down 1.1 percent at $4.73-1/2, keeping on course for a second straight weekly decline. Corn was down 0.4 percent at $3.85-1/4 as it continued to consolidate below a seven-month peak of $3.95-1/4 struck earlier this week. Weather forecasts were projecting some rain in Argentina's parched grain belts in the week ahead, but analysts said benefit for crops would be limited. Argentina's Rosario Grains Exchange on Thursday said the drought, now in its fourth month, would limit the soybean harvest to 40 million tonnes versus its previous estimate of 46.5 million. That was also well below the 47 million tonnes forecast by the U.S. Department of Agriculture (USDA) this month its widely followed world crop report. "According to the USDA, the global soybean market is set to show a supply deficit of 3 million tonnes in 2017/18, even on the basis of the (USDA's) now outdated crop estimate for Argentina," Commerzbank analysts said in a note. "In other words, the deficit is likely to be considerably higher, so the soybean price remains well supported." In the United States, soybean plants crushed more bushels of the oilseed than expected in February, exceeding last year's processing pace for the month National Oilseed Processors Association said on Thursday. However, expectations for increased U.S. soybean plantings this year have capped soybean prices. For wheat, rains next week in the northeast section of the drought-hit U.S. southern Plains are expected to boost soil moisture, although parts of Kansas and Oklahoma are likely to remain abnormally dry, meteorologists said. At the same time, favorable weather ahead of spring grain sowing in Black Sea producers Russia and Ukraine is bolstering the chances of another large harvest due to good levels of soil moisture, analysts and industry officials said. "As far as the Black Sea production looks good, buyers are not too worried about U.S. drought," said one Singapore-based trader who sells wheat to millers across Southeast Asia. "Mills are not going to chase a rally in prices at this stage."

Prices at 1252 GMT

Last Change Pct End Ytd Pct Move 2017 Move CBOT wheat 473.50 -5.25 -1.10 427.00 10.89 CBOT corn 385.25 -1.50 -0.39 350.75 9.84 CBOT soy 1045.50 4.75 0.46 961.75 8.71 Paris wheat May 165.00 -0.50 -0.30 162.50 1.54 Paris maize Jun 164.50 -0.50 -0.30 163.50 0.61 Paris rape May 349.00 0.25 0.07 352.75 -1.06 WTI crude oil 61.36 0.17 0.28 60.42 1.56 Euro/dlr 1.23 0.00 0.15

Most active contracts - Wheat, corn and soy US cents/bushel, Paris futures in euros per tonne

(Reporting by Naveen Thukral in Singapore and Gus Trompiz in Paris Editing by Joseph Radford and John Stonestreet)