Characterization of sweet, fibre and biomass sorghum potential in Portugal as an industrial and energy feedstock

The purpose of this work was to investigate the influence of crop management on the sorghum biomass quality and productivity, in Portugal, in order to access its potential as an industrial and energy feedstock. To do so, the effects of different fertilization levels, the sowing date and the harvest date in the biomass quality and productivity, were studied. Productivity was affected by the level of nitrogen and by the sowing date. Highest productivities were obtained in the most N-fertilised fields and in fields sowed between 251hM arch and 1'' May. Among subspecies, Sweet and Biomass Sorghum presented, globally, higher productivities than Fibre Sorghum. In all the experimental years, highest productivities, in all the fields, were achieved at 193 5 9 days after sowing, regardless of all the different sowing dates. Biomass quality was affected by the crop productivities. Fields with lowest productivities resulted in a biomass with a higher nitrogen and ash contents, namely the fields sowed at 2nd June and the fields without N-fertiliser. In the experimental conditions at Caparica, sweet sorghum crop showed a better potential as an industrial and energy feedstock, and to get better results, economically and environmentally, fields should he sowed between 25‘h March and 1'’ May, with a high nitrogen input (120 kg N/ha).