Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 20, 2012
Publication Date: December 28, 2012
Citation: Burow, G.B., Cotton, J.E., Moore-Kucera, J., Acosta Martinez, V. 2012. Biomass and cellulosic ethanol production of forage sorghum under limited water conditions. BioEnergy Research. 6(2):711-718. Interpretive Summary: To meet the growing demands for food, fiber, and biofuels, land management decisions will require identification of most suitable crop for sustainable productivity in different geographic area. The recent addition of biofuel (fuel produced from renewable resources such as forage crops to supplement fuel demand) as integral facet of agriculture make it more critical that land allocation be carefully managed. As there has been controversy on the use of land that was previously on food production for biofuels, this study examined the use of marginal lands such as semi arid systems that under strict water limitations which may compromise their soil quality. In this study, forage sorghum (Sorghum bicolor L. Moench) cropping systems were initiated in the semiarid Southern High Plains (SHP) of the U.S. to evaluate potential biofuel production and potential benefits on soils that are depleted of organic matter (< 0.7%) due to previous cropping history. This study has evaluated agronomic and cropping systems technology that can be applied towards sustainable sorghum production for integrated bioenergy/forage application with emphasis on minimizing water demand and improving soil quality. Results from this work provide evidence that marginal lands if managed properly for biofuel production may result in an improvement of their soil quality and functioning.
Technical Abstract: A two year field study was conducted to evaluate biofuel production potential of two forage sorghum cultivars differing in brown midrib trait under non-irrigated and deficit irrigation conditions in the semiarid Southern High Plains of the U.S. Cultivar SP1990 (non-bmr = conventional cell wall composition) produced significantly more biomass (29-62%) than PS bmr (reduced lignin) under irrigated and non-irrigated conditions during both years. Irrigation resulted in 26-49% more biomass and 28-72% more EtOH production during both growing seasons, indicating deficit water conditions without irrigation. Reduced lignin content in PS bmr biomass resulted in more efficient conversion (54%) to ethanol (EtOH) during both years. When less water was available due to below average precipitation, both cultivars produced similar amounts of EtOH at each irrigation level supporting the key role of water in biofuel productivity. Accordingly, when more water was available due to above-average precipitation during the second growing season, higher biomass production of SP 1990 resulted in 28% higher EtOH production than PS bmr at both irrigation levels. Overall ethanol production ranged from 1,600 to 3,380 L ha-1 during both years of the study. This study indicates that biomass chemical composition and modification (lignin reduction) and yield potential are critical factors when selecting sorghum cultivars for use as biofuel feedstocks under marginal water-deficit conditions.