Certain crops can yield a significant amount of plant matter at the time of harvest. This plant matter includes almost all of the plant above ground level except grain. Grain is typically harvested and moved from the fields in the case of crops like wheat, corn, soybeans, etc. The remaining plant matter, called crop residue, is left on the farm ground for erosion control, nutrient recycling, and organic matter build-up purposes. Residue removal practices for stover used as bedding for livestock or as silage for feed purposes have been practiced for decades. Spent bedding is typically recycled back on farm ground by land application. Industrial use of crop residue is a new and emerging trend, in addition to its on-going use for Livestock production.
Agri-fiber board manufacturing involves using crop reside use along with certain adhesives. Wheat straw and corn stover have been used to make agri-fiber board, which can be used as replacement for wood for furniture and doors. Such crop residues present opportunities as they can be grown and used locally.
Crop residue consists of cellulose, hemi-cellulose, and lignin (complex sugar polymers) which can be synthesized into ethanol with the exception of lignin. Use of plant matter as a source of complex sugars for ethanol production is turning corn stover, wheat straw, switch grass, etc. into cellulosic feedstocks. Such crop residues are of interest as they can be re-grown and directly used as fuel or converted into solid (compressed pallets), liquid (pyrolysis to bio-crude or char, or hydrolysis of sugars with processing to ethanol, bio-butanol), or gaseous (pyrolysis to gas or gasification to syngas, or biogas from anaerobic co-digestion) forms of energy.
Corn stover is gaining specific attention for industrial uses in Iowa as corn is a major crop grown locally.