Chicago agricultural commodities closed mixed Wednesday. The most active corn contract for March delivery remained unchanged at 7.64 dollars per bushel. March wheat rose 2.75 cents, or 0.31 percent, to settle at 8.9125 dollars per bushel. January soybeans slipped 3 cents, or 0.21 percent, to close at 14.4625 dollars per bushel. Low water levels on the Mississippi River continued to be a support to corn. But the slightly stronger trade in wheat market has been offset by the bearish performance of soybean market, leaving the corn market unchanged. Wheat rose slightly thanks to a strong cash market and the terrible weather conditions in the U.S. western plains, which has aggravated investors\' worries over tight winter wheat supply in 2013. Besides, the U.S. soft red winter wheat has been competitive on the world\'s market, and some traders are expecting the U.S. wheat export sales to pick up in 2013, which could add an additional support to wheat trade. January soybean gained slightly on the concern that the low water levels on the Mississippi River may reduce the supply, but the gain is limited due to favorable weather outlook for South America in the coming weeks, when most of the area will see rainfalls.