Typical corn stover harvest occurs within a short time frame anywhere from a few days to a few weeks following grain harvest. In Iowa, this harvest occurs prior to fall tillage and fertilization. PM 3051B - Corn Stover Harvest Window explains the variability in the time period available for stover harvest.
Several unit processes are involved in getting the corn plant material into bales. These processes may include shredding, windrowing, baling of the stover and gathering the distributed bales and moving them to storage sites. PM 3051A - Corn Stover Harvest Machinery describes the various performance details of equipment involved in corn stover harvest.
Windrowing of Corn Stover
Windrowing refers to the placement of corn stover material into rows of appropriate size suitable for baling. The windrowed stover can then be collected in the baling process and put together into round or square bales. The amount of material windrowed depends upon the height of cut, number of rows on the corn head, combine head chopper settings, combine spreader settings, and any subsequent shredding of plant material.
Baling of Corn Stover
The baling process is an additional machine pass on the field that produces round or square bales by picking up and compacting the loose windrowed stover material. The type of equipment used defines the configuration and density of the bale. Material baled is directly dependent upon the material windrowed.
PM 3051H - Productivity of Corn Stover Bale Handling Systems describes the commercial scale squeeze loading systems and automatic load securement trailers.
Collection of Stover Bales
Gathering the bales and moving them to a storage site is a critical step in the industrial harvest of corn stover. Different types of equipment currently available on the market allow for multiple bales to be collected at the same time, whether the bales are round or square. Collection and movement of large bales to the end of the field is typically achieved by the use of hydraulically powered lift tables or bale racks. The hydraulic lift arms pick up and place the bales on the tables/racks for moving them to the edge of the field or a storage site.
Transportation of Bales
Supply chain needs will require a daily or an every work-day transportation of bales from storage sites to the industrial plants. It is estimated that the 25-million-gallon cellulosic ethanol plants being built in Iowa will require approximately 400,000 dry tons of corn stover per year. This translates to approximately 60 semi-loads of stover per day running between storage sites and the plants. Whether rounds bales or square bales are transported, consideration should be given to Iowa Department of Transportation regulations. PM 3051G - Transportation Biomass on Iowa Roadways describes the vehicle length, width, and height restrictions in terms of number of bales on the load.