* Soy, corn, wheat pull back from multi-year highs

* Brazil, Argentina showers ease soy, corn crop concerns

CHICAGO, Jan 20 (Reuters) - Chicago soybean futures fell on Wednesday, touching their lowest in more than a week, pressured by technical selling combined with rains across South America which ease supply concerns.

Corn followed, also pressured by beneficial South American rains, while wheat hovered just under even, supported by export optimism.

The Chicago Board of Trade (CBOT) most-active soybean contract was down 6-3/4 cents at $13.79 per bushel by 11:56 a.m. (1756 GMT).

CBOT corn slid 1-1/2 cents to $5.24-1/2 per bushel, while wheat was 1-1/4 cents lower at $6.71 per bushel.

Soybeans fell 32 cents in early-session trading, before regaining ground midday, as funds sold long positions.

"We’re just seeing a little setback due to profit taking, after the improvement of South American weather," said Terry Reilly, senior analyst with Futures International, noting that the market needs to see additional exports or further dryness in Brazil or Argentina to move higher.

China's soybean imports from the United States rose 52.8% in 2020, according to U.S. Customs data.

Soybeans could face increased volatility as markets look for direction before the South American harvest begins in force.

"It’s going to take more bullish news to get this thing back toward its highs," said Dan Smith, senior risk manager at Top Third Ag Marketing. "I’m looking for a high volatility period in the next month."

Meanwhile, wheat traded just under even, supported by impending Russian export taxes, though expected rainfall across the United States muddied the trading waters on Wednesday.

"The eastern areas of the U.S. southern Great Plains are expected to get some precipitation over the next seven days, which is good for the winter wheat crop," said Reilly.

Corn slipped overnight but regained much of the losses.

The U.S. Environmental Protection Agency on Tuesday granted three waivers to oil refiners that exempt them from biofuel blending obligations, a last-minute move before President Donald Trump leaves office. (Reporting by Christopher Walljasper; additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore. Editing by Mark Potter)