Suitability of cardoon (Cynara cardunculus L.) harvested at two stages of maturity to ensiling and methane production

A sustainable biogas production requires the use of a biomass that is not in competition with food production and does not require a high energy input for its production. Cardoon (Cynara cardunculus L.) was evaluated at ensiling to establish its suitability for methane production. The cardoon was harvested at full bloom (Stage I) and seed ripening (Stage II), and was then treated with lactic acid bacteria (LAB). Higher fermentative products (lactic acid and ethanol) and DM losses were determined at Stage I than at Stage II. The advanced stage of maturity (Stage II) determined a higher fiber content and lower methane yield per tonne of volatile solids than at Stage I. No difference was observed between the methane production at harvesting and that after ensiling, thus indicating the ability of the ensiling process to conserve most of the energy of the crop at harvesting.