GRAINS-U.S. soybeans, corn tumble as China includes crops in tariff riposte

* China says tariffs on $50 bln U.S. goods include soybeans, corn

* Soybeans fall as much as 5 pct, corn 4 pct

* Investors rattled as China targets huge soybean trade flows

* Analysts skeptical that China could avoid U.S. soybeans

(Recasts with price drop after China's announcement of tariffs on U.S. goods) PARIS, April 4 (Reuters) - Chicago soybean futures plunged on Wednesday after China rattled investors by including the crop in retaliatory tariffs against the United States, despite its heavy reliance on U.S. supplies of the oilseed. U.S. corn fell sharply too as the feed grain was also mentioned in a list of goods worth $50 billion subject to a 25 percent additional import tax.

Chicago Board of Trade soybean futures, which had traded little changed prior to the news of China's tariffs, fell as much as 5 percent to $9.83-1/2 a bushel, the lowest in almost two months, breaching the $10 psychological barrier. "The big reaction is on soybeans because the trade impact is the greatest, with 35 million tonnes of U.S. soybeans imported a year by China," said Michel Portier, head of consultancy Agritel. "But I think the price move looks excessive because South America cannot replace the U.S. in supplying soybeans to China, especially with the drought in Argentina." Widespread expectations that China would keep soybeans out of retaliatory trade measures left some investors surprised by Wednesday's announcement and fearful of trade disruption. "A big market storm is brewing," one European trader said. "This will bring huge disruption to the world soybean market, in my view." CBOT corn was down 3.9 percent at $3.73-1/2 a bushel, after falling to as low as $3.72. China, which also imports U.S. corn, listed the feed grain among agricultural products to be subject to extra tariffs. CBOT wheat tracked the losses in soybeans and corn, slipping 1.3 percent to $4.51.1-/2 and giving up an earlier gain linked to poor crop conditions for U.S. wheat. Analysts cautioned that details were still needed on how and when China would implement the tariffs. "Confirmation of the details are needed for a full assessment, but it seems there will be an import levy on U.S. soybeans," said Matt Ammermann, Commodity Risk Manager at INTL FCStone. "In the near term it looks bearish for prices as some investors are selling futures right now and will likely ask questions later."

Prices at 0913 GMT

Last Change Pct End Ytd Pct Move 2017 Move CBOT wheat 451.50 -6.00 -1.31 427.00 5.74 CBOT corn 373.50 -15.00 -3.86 350.75 6.49 CBOT soy 990.25 -47.75 -4.60 961.75 2.96 Paris wheat May 165.50 -0.75 -0.45 162.50 1.85 Paris maize Jun 165.25 -1.25 -0.75 163.50 1.07 Paris rape May 349.00 -2.75 -0.78 352.75 -1.06 WTI crude oil 62.29 -1.22 -1.92 60.42 3.10 Euro/dlr 1.23 0.00 0.18

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

(Additional reporting by Sybille de La Hamaide in Paris, Michael Hogan in Hamburg and Colin Packham in Sydney Editing by Manolo Serapio Jr. And Louise Heavens)