The grains have turned mixed in early trading Thursday, with corn and wheat lower while soybeans hang on to a slight upward ledge.

In morning trading, December 2010 corn futures are trading 5 cents lower at $5.68 1/2 per bushel, while December wheat is 9 1/4 cents lower at $6.73 3/4, according to Barchart.com. November soybeans are clinging to a 3/4 cent gain at $12.12 3/4 per bushel.

Exports are keeping soybeans from turning lower so far, according to a Dow Jones Newswires report, while corn is slipping mostly from lower-than-expected weekly export demand figures.

But, the U.S. Dollar index remains the biggest factor in the pits in Chicago, says CME options trader, GFI Group ag products manager and Bradford Capital Management CEO in Chicago, Scott Shellady.

"Still a dollar based trade. Not what I like to see but that is the world we live in," he says Thursday morning in a Marketing Talk discussion. "So far the dollar is quiet which means we will be as well."

• See more commodity prices