John L. Smith, the football coach for the University of Arkansas, has filed for bankruptcy protection over debts he incurred through real estate investments in Kentucky, the Associated Press reported yesterday. Documents filed in the case show Smith has assets of between $1 million and $10 million and debts of between $10 million and $50 million. Smith said in July that he began the land investments when he was coach at Louisville from 1998-2002 and that he and other investors lost money when the real estate market softened.