Colture energetiche - produzione e bilancio energetico in coltura di sorgo (Sorghum bicolor (L.) Moench) da biomassa coltivato in Italia centrale

Introduction. Nowadays the utilisation of alternative energetic resources represents a valid tool in greenhouse gas reduction. In particular, the utilisation of biomass crops plays a strategic role in protecting environment and supporting rural development and employment. Sorghum (Sorghum bicolor (L.) Moench) is undoubtedly one the most important biomass herbaceous crops, especially in environments such as those of Mediterraneanarea. The research activity, inserted in the ambit of a project supported by the company Energy Agri Srl for electric energy production by biomass combustion, aimed to evaluate productive performances and responses to different agricultural conditions of biomass sorghum crops. Materials and methods. Four experimental sites were chosen as representative of homogenous agricultural and pedo-climatic areas. Low input technical itinerary were adopted in order to maximize the energetic balance. Experimental sampling were randomly done in each fields assessing sorghum productive parameters. Energetic balance were calculated by quantifying energetic flows in each sites. Results and discussion. The results highlighted a significative difference in crop behaviour in function of cultivation environment and, specifically, of technical itinerary adopted by project farms. These differences concerned both final production and plant development, assessed by measurement of quantitative variables such as plant height, tiller number, fenological plant phase length. Specifically, sorghum grown in the locality Collesalvetti gave the highest performances. Nevertheless less pronounced differences were observed in terms of energetic balance, which resulted positive in all experimental areas. In fact, the low productivity level associated to zero tillage techniques was balanced in terms of energetic efficiency. The most important items were cultivation and fertilisation modalities. Conclusion. Besides highlighting the energetic convenience of biomass sorghum cultivation in the experimental area, the results obtained indicate the need in selecting varieties not only with high production standard but also more reliable and less exigent to be inserted in low input cropping systems in order to optimize the energetic chain and make the energetic process more efficient.