Corn Residue as a Feedstock for Cellulosic Ethanol

By Kolby Hoagland | September 13, 2013

This week, Biomass Magazine took part in the National Advanced Biofuels Conference & Expo and the Corn Stover Harvest & Transport Seminar, which were held in conjunction at the CenturLink Center in Omaha. I was given the honor to MC the Corn Stover Harvest & Transport Seminar where soil scientists, crops specialists, equipment manufacturers, farmer associations, and numerous other experts from industry and academia candidly discussed how corn residue ought to be harvested and aggregated to maintain soil quality and provide a consistent feedstock for cellulosic ethanol plants. In this week’s DataPoint, I will build on a previous article by Anna Simet and provide an in-depth analysis on the benefits of combining corn residue removal with no/low-till field management.

The first panel of the Corn Stover Harvest & Transport Seminar, “From Soil to Pump: The Impact of Organic Matter and Nutrient Loss on Our Farmland,” looked at key considerations of corn residue removal on soil conservation and corn yield improvement. The presenters from ARS, Monsanto, and Iowa Corn provided a succinct research-backed that either too little or too much stover left on a field can have negative effects to subsequent corn crops and soil health. The panelists agreed that no-till and low-till field management schemes are some of the most effective practices for farmers to protect their soil from erosion, soil organic matter volatilization, and nutrient run-off. As average annual corn yields trend upwards, the reduction of corn residue left from the previous year’s grain harvest becomes more important. Corn residue encountered during planting in the spring poses a number of problems to farmers. Fall and spring tillage have historically been practiced to incorporate the previous season’s corn residue back into the soil in order reduce the quantity left on the surface of the field. The prime motivators of plowing corn residue back into the soil are to reduce pathogens that might be in the residue and to encourage better seed to soil contact, which excess corn residue inhibits. Plowing the corn residue back into the field provides a clean and even seed bed for strong stand establishment. Furthermore, tillage schemes have been practiced by generations of farmers and are a proven way to manage residue.

The panel acknowledged the historic nature of tillage practice, but also conveyed the negative consequences tillage poses to soil health and yield. Once the residue has been tilled back into the soil, the carbon in the previous year’s corn residue binds nitrogen that would otherwise be available to the current corn crop. Furthermore, the tillage of agricultural soil volatilizes considerable quantities of soil organic matter, destroys soil aggregates, and encourages erosion and runoff. By combining no/low-till practices with stover removal in field management schemes, studies not only show yield increases in subsequent corn crops but improved soil health. Soil aggregates are maintained in the fields soil profile, valuable soil organic matter is prevented from volatilizing to the atmosphere, and healthy amounts of stover are left on the field to protect from erosion and runoff when stover removal and no/low-tillage practices are combined in a field management shceme. The panel determined that pairing crop residue removal with no/low-tillage practices would support farmer’s intent to manage excess crop residue, support soil health, and provide sufficient quantities of feedstock to the burgeoning cellulosic ethanol industry.

The in-field variability of soil and the dynamic relationship that corn residue has on positive and negative yield effects necessitate ingenuity and practice. The conclusion of the panel stated that corn stover can be done in a manner that would sustain soil health when paired with no and low-till practices. The experiences gained by farmers supplying Abegnoa Bioenergy Biomass of Kansas, DuPont Cellulosic, and Poet-DSM will support a better understanding of best practices for future suppliers of corn residue to the burgeoning cellulosic ethanol industry.