Energy crops: the research on biomass sorghum at Bologna University

none2The UE legislation plans rising targets for bio-energy plays, in the effort to reduce the greenhouse gas emission, which is responsible for the climate change. Dedicated crops may contribute to reach these targets, integrating the supply of residual biomass and wastes of several sources. The recent pressure on agricultural prices has spurred a food vs. fuels argument, in turn addressing energy-crop choice towards species which are only suited for non-food uses. Many biomass crops conform to this requirement; biomass sorghum is one of the best suited for a vast array of growing conditions. This crop belongs to the same species as grain sorghum (Sorghum bicolor); differences concern plant height and the prevalence of the vegetative organs on the grain in the biomass genotypes. In the last twenty years the Research Group on Industrial Crops (GRiCI) at DiSTA, Bologna University, has been active in researches on the topic. The work has developed through a series of projects funded at regional, national and European level. The first researches were focused on the general adaptation of several genotypes of biomass sorghum (sweet and fibre types) to the cropping environment. Subsequent studies were aimed at a deeper insight into: plant composition as related to end uses; responsiveness to low-input crop techniques; at last, interaction between cropping factors and harvest methods. These researches, ended a few years ago, have confirmed the substantial suitability of the crop to the conditions of the Po River plain. At present, trials are being carried on focusing on the management of cropping factors. The aim is to better exploit the species’ potential, as a condition for productions competitive in financial terms as well as efficient in terms of energy and non-renewable resources. Among them, the researches on plant density deserve to be mentioned: it appears as plant density may be further reduced with respect to the current advice of 12-15 plants/m²; the benefits are for plant stability in strong winds. Another undergoing activity is the study of the interaction between genotypes and harvest times: a fibre hybrid and a forage one (“Sudan” type) are compared, in combination with a single harvest at the end of growth (September) and with a double harvest (at flowering and in autumn on the regrowth), under conditions of rainfed and irrigated crop. From the first results, the advantage of the double harvest appears uncertain, even under irrigation. Conversely, it is remarkable and deserves deeper insight the possibility of using a forage sorghum, creating a more compact and elastic stand, compared to a fibre type. At last, in a comparison among annual species for various energy sectors (biogas, thermo-electric energy, bioethanol and biodiesel), biomass sorghum has ranked first over the others (cereals, oilseeds, sugar beet), for both dry matter yield per hectare, as for potential output of ethanol (1st and 2nd generation), thermo-electric energy and biogas. On concluding, regardless of the energy sector, biomass sorghum is shown as the most promising dedicated crop among annual ones. Also the use efficiency of water and energy inputs are the highest, to the benefit of the environment. Further progress is expected from the work of the breeders and of the seed firms, which only lately seem to have seized the species’ relevance. Potential outcomes will be monitored and evaluated in view of a comprehensive optimization of the bio-energy chain.BITES Project International Conference; www.biofuelshowcase.eumixedL. Barbanti; G. VenturiL. Barbanti; G. Ventur