DuPont Danisco Cellulosic Ethanol LLC, a subsidiary of  E.I. du Pont de Nemours & Co., said Monday that it has agreed to buy a parcel of land in Nevada for construction of a refinery to convert crop stover into ethanol. The site is adjacent to Lincolnway Energy LLC’s ethanol plant. DuPont Danisco said it is launching a stover collection program to to supply the biorefinery. Stover is the cobs, stalks and leaves of plants, including corn and wheat, that remain after grain is harvested.