Improving Biomass and Ethanol Yield by Intercropping a Winter Cereal with Corn

Abstract

Core Ideas Incorporation of a cover crop improved ethanol and biomass yield regardless of harvest time. Stover‐only treatments yielded greater ethanol and biomass when harvest in the fall. Despite differences in fermentable sugars among feedstocks, biomass yield was the strongest driver of per hectare ethanol yield. Corn (Zea mays L.) stover is readily available and can be used as a feedstock for cellulosic ethanol. The addition of a winter annual cereal crop to the corn stover system could increase potential ethanol yield by adding harvestable biomass. The objective of this study was to evaluate the potential bioethanol yield resulting from the harvest of mixed stands of corn stover interseeded with winter cereals. The winter cereal crop factor consisted of three treatments; cereal rye (Secale cereale L.), triticale (Triticale hexaploide Lart.), and no winter cereal crop (control). The harvest time factor consisted of two treatments; a two‐harvest system (fall + spring), and a one‐harvest system (fall or spring). Two‐harvest feedstock ethanol content [EtOH] was the greatest (0.305 kg kg−1 and 0.307k g kg−1) followed by the spring‐harvested stover (0.201 kg kg−1). Biomass production and [EtOH] were then multiplied to calculate ethanol yields. Ethanol yield (L ha−1) decreased by 47% when stover‐only feedstock was harvested in the spring compared to the fall. When only considering a single harvest system, incorporation of a cover crop did improve ethanol yield by 242 L ha−1 at spring harvest. The two‐harvest mixed feedstock system was the most productive with 41.8% greater ethanol yield when compared to the single harvest. Overall, the mixed biomass feedstocks resulting from the incorporation of a winter annual cereal with corn stover improved biomass yield and [EtOH] relative to stover‐only feedstocks.