Archer Daniels Midland Co., the leading U.S. oilseed crusher, said on Monday its soybean crushing plant in Little Rock, Arkansas, will be shut down indefinitely. "It started with a mechanical failure. Then we looked at margins and the decision was made to keep it down indefinitely,"said Larry Cunningham, ADMspokesman. In recent months, U.S. soybean crushers have reported lower cash crushing margins, largely in reaction to low soybean product prices. Soymeal prices have dropped about $30 per ton since Jan. 1. Soybean oil prices at the Chicago Board of Trade have recently traded near 10-year lows. Reuters