Biomass supply for energetic purposes from some Cardueae species grown in Mediterranean farming systems

Abstract

In order to explore complementary biomass sources, field studies were conducted on Cynara cardunculus botanical varieties (globe artichoke and cultivated cardoon) for energy purposes. In addition, the potential of milk thistle (Silybum marianum L. Gaertn.) as a suitable energy crop for Southern Europe countries was investigated. The three different crops were compared over three years (2007–2010) in a Mediterranean environment (Sardinia, Southern Italy) for quantitative and qualitative (calorific value, ultimate and proximate analyses, ash composition) biomass characteristics.Annual biomass production across years averaged about 10, 4, and 16Mgha−1 in cardoon, globe artichoke and milk thistle, respectively. The chemical analysis of biomass showed a similar composition among crops with a mean ash content of 14% and a higher calorific value of about 17MJkg−1. Annual energy yield ranged between 64GJha−1 reached by globe artichoke and 275GJha−1 reached in milk thistle. The exploitation of globe artichoke crop residues for energetic purpose can represent a complementary income for farmers. The present study confirms the good biomass yield of cardoon in cultivation systems characterized by limited water input and indicate milk thistle as a promising crop for biomass production. Future work is necessary in order to investigate different genotypes of the three crops for potential biomass and grain yield and their chemical composition, to detect agronomic practices suitable to optimize qualitative crops performances and to set up specific cropping systems.