Abstract
Utilizing agricultural residues for energy and heating purposes is gaining momentum in the EU and even more in areas where biomass is a fundamental pillar of the economy like, e.g. South Tyrol in N Italy. In previous studies, four different types of agricultural residues were pelletized and combusted in a commercial boiler. This study has the scope to assess the suitability of biomass ashes as soil fertilizers. In this analysis potassium is identified as a key indicator for the nutrient content of biomass residue ashes. Therefore, this study introduces a new factor for assessing the utilization potential of biomass residues ashes, which is defined as the "potassium utilization potential factor" or KUP factor (with K representing potassium). The analysis is based on combining the initial concentration of potassium in the feedstock and the efficiency of statistical entropy. Statistical entropy analysis showed that combustion had a diverse substance concentrating efficiency of potassium for the four different types of biomass, ranging from 25 - 40 %. In total, apple logs and apple pruning had the best performance in respect to their suitability as soil fertilizer since these feedstocks had the highest KUP factors.