Distribution of structural carbohydrates in corn plants across the southeastern USA

Authors: MOURTZINIS, SPYRIDON - Auburn University; Cantrell, Keri; ARRIAGA, FRANCISCO - University Of Wisconsin; Balkcom, Kipling; Novak, Jeffrey; FREDERICK, JAMES - Clemson University; Karlen, Douglas

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2014
Publication Date: 2/9/2014
Publication URL: http://handle.nal.usda.gov/10113/62869
Citation: Mourtzinis, S., Cantrell, K.B., Arriaga, F., Balkcom, K.S., Novak, J.M., Frederick, J.R., Karlen, D.L. 2014. Distribution of structural carbohydrates in corn plants across the southeastern USA. BioEnergy Research. 7(2):551-558.

Interpretive Summary: Corn stover, the above-ground stalk, leaves, tassels, and cobs remaining after grain harvest have been identified as an important potential feedstock for second generation biofuel production. Therefore, it is important to know more about the anticipated ash, lignin and structural carbohydrate (cellulose and hemicelluloses) composition of these materials and how they are affected from year to year by management practices such as growing a cover crop and different rates of stover harvest. We found significant variations in the distribution of all three plant components. But neither the use of a rye cover crop nor the stover harvest rates affected carbohydrate concentrations within the various plant fractions or across soil types. Total precipitation and average air temperature during the growing season were strongly correlated with stover composition indicating the effect of weather conditions on biofuel production. When compared to the above-ear fractions, bottom plant partitions contained greater lignin and cellulose concentrations. Cellulose and hemicellulose concentrations were consistently greater in cobs, tops and above-ear fractions at every location. This study suggests that the cob, top and above-ear plant portions have the most desirable characteristics for bioethanol production via fermentation and will be useful to developing those industries in the southeastern U.S.

Technical Abstract: Quantifying lignin and carbohydrate composition of corn (Zea mays L.) is important to support the emerging cellulosic biofuels industry. Therefore, field studies with 0 or 100% stover removal were established in Alabama and South Carolina as part of the Sun Grant Regional Partnership Corn Stover Project. In Alabama, cereal rye (Secale cereale L.) was also included as an additional experimental factor, serving as a winter cover crop. Plots were located on major soil types representative of their respective states: Compass and Decatur soils in Alabama; a Coxville/Rains-Goldsboro-Lynchburg soil association in South Carolina. Lignin and structural carbohydrate concentrations in the whole (above-ground) plant, cobs, vegetation excluding cobs above the primary ear (top); vegetation below the primary ear (bottom); and vegetation from above the primary ear including cobs (above-ear) were determined using a combination of wet chemistry methods and near-infrared spectroscopy (NIRS). The distribution of lignin, ash, and structural carbohydrates varied between sites, but neither inclusion of a rye cover crop nor the stover harvest treatments affected carbohydrate concentrations within the various plant fractions or for the soil types. Total precipitation and average air temperature during the growing season were strongly correlated with stover composition indicating that weather conditions may have multiple effects on potential biofuel production (i.e., not only yield but also stover quality). When compared to the above-ear fractions, bottom plant partitions contained greater lignin and cellulose concentrations. Holocellulose concentration was consistently greater in cobs, tops and above-ear fractions at both locations. Data from this study suggests that the cob, top and above-ear plant portions have the most desirable characteristics for bioethanol production via fermentation in the southeastern US.