A comparative study to assess the production of two oilseed crops (Brassica carinata A. Braun and Carthamus tinctorius L.) and the energy potential of their agricultural biomass residues

Ethiopian mustard (<i>Brassica carinata</i> A. Braun) and safflower (<i>Carthamus tinctorius</i> L.) are two oilseed crops which have been largely developed as biofuel feedstock. Their agricultural residues can be also valorised for generation of renewable energy directly on-farm conforming to sustainability goals. This study aimed to compare the yield performances of Ethiopian mustard and safflower under rainfed conditions, assess the energetic characteristics of agricultural residue and pellet and calculate the agricultural residue energy potential. Two-year tests were carried out in Sicily (Italy) comparing 20 accessions of Ethiopian mustard and 19 accessions of safflower. Seed yield (SY) and agricultural residue yield (ARY) were obtained on a harvest area of 7 m². Ash content, moisture content, higher heating value (HHV) and lower heating value (LHV) of the agricultural residues were calculated. HHV and mechanical durability of pellets were recorded. Theoretical biomass potential (TBP), theoretical biomass energy potential (TEP) and available biomass energy potential (AEP) of residues were subsequently determined. The economic impact derived by cultivation of the two crops was also evaluated. Ethiopian mustard produced the highest average SY (2.9 t ha^-1) and ARY (7.8 t ha^-1), in both growing seasons. Significant differences were found concerning agricultural residues in moisture content and non-significant differences in HHV and LHV in both species. The pellets made from the two oilseed crops residues were modestly suited for energy use. Ethiopian mustard performed better than safflower in terms of TEP (91.27 GJ ha^-1) and AEP (66.63 GJ ha^-1) and could be considered of greater interest for valorisation of agricultural residues to renewable energy. These findings confirm the good productivity of the two crops in the Southern Mediterraean area and, particularly, highlight the greatest economic profitability of safflower (484 € ha^-1) when considering also the seed sale price.