Double-cropping sorghum for biomass production
Steven L. Fales
The production of biomass using double-cropping systems may have the advantage of producing more feedstock for refineries by extending the growing season, while also providing many environmental benefits, such as the reduction of erosion. Past research indicates that there may be a genotypic effect for the suitability of a crop for use within these systems. There has been little research conducted to explicitly examine this effect in sorghum, despite the crop's diverse genetic background. The objective of this study was to evaluate the biomass production of twelve sorghum genotypes grown as a sole crop and within a double-cropping system with triticale. It was shown that both triticale and sorghum are acceptable as potential feedstocks for ethanol conversion. Because of adverse weather conditions, the chemical composition of both crops varied over all study environments and was the result of the differences in maturity at the time of harvest. Although genotypes within the single-cropping system produced higher biomass system yields than the double-cropping systems, the difference was not significant for several genotypes. These sorghums were characterized as being earlier maturing varieties and had nearly maximized dry matter production at the earlier harvest of the double-cropping system. Thus, the additional biomass that the crop would have accrued was capable of being supplemented by the growth of the triticale. However, the theoretical ethanol yields were significantly higher within the single-cropping system for these cultivars. This indicates that although it could offset any loss in dry matter production, the triticale crop was of lower quality for conversion to ethanol compared to the sorghum biomass. The double-cropping systems were more costly to produce than the single-cropped sorghums; however, there are favorable environmental benefits associated with the double-cropped sorghum that may warrant the additional costs.