Nitrogen and Tillage Management Affect Corn Cellulosic Yield, Composition, and Ethanol Potential

Corn (Zea mays L.) stover and cobs remaining after grain harvest can serve as a feedstock for cellulosic ethanol production. Field trials were conducted at two locations in Minnesota over three years to determine how corn cellulosic yield composition and ethanol yield are influenced by tillage system [chisel tillage (CT), strip-tillage (ST), and no-tillage (NT)] and fertilizer N rate (0, 45, 90, 134, 179, and 234 kg N ha⁻¹). Stover biomass yield, C and N concentrations and content, and potential ethanol yield increased with increasing fertilizer N rate. Stover biomass yield, C content, and potential cellulosic ethanol yield were less with NT than CT and ST by ≥9, 8, and 8 %, respectively. Theoretical ethanol yield of stover was maximized at a fertilizer N rate lower than the economically optimum N rate (EONR) for grain yield. Cob biomass yield, C concentration and content, N concentration, and potential ethanol yield increased with fertilizer N rate, but not at the same magnitude observed for stover. Tillage system did not influence cob biomass yield, C and N concentrations and content, or potential ethanol yield. These results demonstrate that biomass and ethanol production of stover and cobs can be affected by N and tillage management. Cobs may be a more viable feedstock option than stover because nearly all measured variables were less sensitive to management and their harvest removes less C and N from a field compared to full harvest of combined cobs and stover.