GRAINS-Soybeans slide on slowing U.S. exports, Argentina rains

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By Karl Plume

CHICAGO, March 17 (Reuters) - U.S. soybean futures retreated on Wednesday on slowing export sales as global demand shifts to South American supplies and as U.S. farmers prepare to dramatically increase plantings of the oilseed this spring.

Corn futures were mixed, with the nearby contract firming as strong sales to China stoked concerns about tightening supplies.

Wheat eased, led by hard red winter wheat contracts on improving crop conditions following rains in the U.S. Plains and signs of a larger-than-expected crop in top supplier Russia. nR4N2KS013

The soybean slide anchored grain prices in general, as improving rains in dry areas of Argentina and projections for a bumper Brazilian harvest weighed on prices.

However, lingering concerns about harvest delays in Brazil, the world's top soy exporter, limited declines. nS0N2FH02O

"We're coming to the end of our (soybean) export period, the South American weather premium is coming out and it's too early to put in a weather premium here in the U.S.," said Craig Turner, a commodities broker with StoneX.

"Bull markets need to be fed and we're not getting any day-to-day bullish news on the beans to support prices where they are right now," he said.

Chicago Board of Trade May soybean futures SK1 fell 5-1/2 cents to $14.17-3/4 a bushel, although prices remain near multi-year peaks hit earlier this month.

May corn futures CK1 were 3-3/4 cents higher at $5.58 a bushel after touching a near three-week high after the U.S. Department of Agriculture (USDA) confirmed large sales to China for a second straight day. Deferred contracts were all lower.

The USDA has confirmed 2.38 million tonnes in U.S. old-crop corn sales to China over the past two days. The department is due to release weekly export sales data early on Thursday. nFWN2LF0PK nFWN2LF0PK

CBOT May wheat WK1 fell 7 cents to $6.40 a bushel, while May K.C. HRW wheat KWK1 dropped 7-1/4 cents to $6.01 a bushel.

(Additional reporting by Naveen Thukral in Singapore and Sybille de La Hamaide in Paris; Editing by Marguerita Choy)

((karl.plume@thomsonreuters.com; +1 313 484 5285; Reuters Messaging: karl.plume.thomsonreuters.com@reuters.net))