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Uncertainty in predictions of long-term yields of perennial grasses makes business plans untenable in the short run. Long-term data across varied environments, including marginal lands, will help in preventing uncertainty while providing farmers and entrepreneurs with sound information to estimate reliable and affordable strategies on what, where, and how long to grow perennial grasses. In the present study, the long-term yields (11 to 22years) of switchgrass (Panicum virgatum L.), miscanthus (Miscanthus × giganteus Greef et Deuter), and giant reed (Arundo donax L.) grown in northern and southern Mediterranean environments are reported. Switchgrass was grown in Greece and northern Italy, giant reed in southern and northern Italy, and miscanthus in southern Italy. Furthermore, lowland and upland switchgrass ecotypes were compared in Greece. Despite similar biomass productions (9.8 and 10.0Mg DM ha−1 for uplands and lowlands, respectively), the upland ecotypes showed a significantly higher yield stability (CV of 24 and 32% for uplands and lowlands, respectively) over a 17-year period. Biomass yield varied considerably across years and locations; giant reed outperformed switchgrass under northern Italy environment (21.2 and 13.6Mg DM ha−1 for giant reed and switchgrass, respectively). Annual yield of switchgrass was 30% higher in the north than south Mediterranean; miscanthus showed intermediate production compared to giant reed and switchgrass (average of 22years) and a CV similar to switchgrass. In summary, these results evidence that multi-location, long-term trials are strongly needed to reduce uncertainties on crop yield variability and provide more accurate data from which optimized socio-economic and environmental predictions can be achieved.

Side by side biomass productivities, harvesting time (autumn vs. winter) and frequency (annual vs. biennial) of three perennial grasses were compared under northern and southern Mediterranean climates. Miscanthus ( Miscanthus × giganteus Greef et Deu.) was compared to giant reed ( Arundo donax L.) in Catania (37°24′N, 15°03′E), and to switchgrass ( Panicum virgatum L.) in Bologna (44°55'N, 11°45′E). Generally, giant reed produced about 50% higher biomass than miscanthus in Catania. Miscanthus almost halved biomass productivity in the driest year, while giant reed reduced biomass yield by only 30% under the same conditions. In Bologna, miscanthus and switchgrass produced similar amounts of cumulative biomass over 6 years. Switchgrass kept more stable annual yields than miscanthus, which, however, evidenced a higher potential under favorable climate conditions. Autumn harvest significantly reduced biomass productivity and quality (moisture content, ashes, cellulose and hemicellulose), particularly under South Mediterranean climate. In Catania, autumn biomass was 50% (giant reed) to 85% (miscanthus) lower than winter biomass, while in Bologna, autumn cut reduced switchgrass yield by 20%. Biennial harvesting resulted in almost 40% lower cumulative biomass yield than annual cut, after 6 years.

Biogas production can be considered an important technology for the sustainable use of agricultural biomass as a renewable energy source even more when the substrates for anaerobic digestion are crop residues, livestock residues or energy crops that don’t compete with food crops for land use. The aims of this study were to evaluate the production of biogas and biomethane from two lignocellulosic crops suitable for the Mediterranean environment (Arundo donax L. and Saccharum spontaneum subsp. aegyptiacum (Willd.) Hack) and the efficiency of a thermal pretreatment to increase the biomethane production. The purpose of the pretreatment is to break the recalcitrant lignin layer, so that the cellulose and hemicellulose present in the biomass are hydrolyzed by microorganisms and converted into simple sugars to achieve greater energy yield.

In recent years it was observed a renewed interest for hemp (Cannabis sativa L.) cultivation, both as industrial and food crop. The interest as food crop lays in the nutritional values of hemp seeds mainly related to their high-quality oil and proteins contents. As reported by Amaducci et al. (2015), hemp fibre can also be used as reinforcement in composite materials, to produce insulation mats, car interior panels, and requested in bio-building sector to form concrete too. The possibility to cultivate hemp for a dual purpose use could improve the farmer revenue. The information regarding the dual purpose hemp cultivations are poor and even more in Mediterranean environments. In this respect the present study evaluated the adaptability of Futura 75 hemp genotype under the Mediterranean conditions of Southern Italy (Sicily).

Biogas production can be considered an important technology for the sustainable use of agricultural biomass as a renewable energy source even more when the substrates for anaerobic digestion are crop residues, livestock residues or energy crops that don’t compete with food crops for land use. The aims of this study were to evaluate the production of biogas and biomethane from two lignocellulosic crops suitable for the Mediterranean environment (Arundo donax L. and Saccharum spontaneum subsp. aegyptiacum (Willd.) Hack) and the efficiency of a thermal pretreatment to increase the biomethane production. The purpose of the pretreatment is to break the recalcitrant lignin layer, so that the cellulose and hemicellulose present in the biomass are hydrolyzed by microorganisms and converted into simple sugars to achieve greater energy yield.

Mediterranean climates are characterized by long periods of drought during summer and short dry periods from autumn to spring, what limits plant CO2 assimilation and biomass production to a great extent. The JRC has set a series of thresholds to define marginal lands in terms of biophysical constraints. We focus on climate limitation given by the ratio between precipitations and potential evapotranspiration (P/ET). Areas with P/ET ≤0.60 are classified as affected by “dryness”. The present study follows up a long-term plantation of the C4 perennial grass Saccharum spontaneum ssp. aegypticum under different water regimes in a semi-arid Mediterranean environment.

Mediterranean climates are characterized by long periods of drought during summer and short dry periods from autumn to spring, what limits plant CO2 assimilation and biomass production to a great extent. The JRC has set a series of thresholds to define marginal lands in terms of biophysical constraints. We focus on climate limitation given by the ratio between precipitations and potential evapotranspiration (P/ET). Areas with P/ET ≤0.60 are classified as affected by “dryness”. The present study follows up a long-term plantation of the C4 perennial grass Saccharum spontaneum ssp. aegypticum under different water regimes in a semi-arid Mediterranean environment.

In recent years it was observed a renewed interest for hemp (Cannabis sativa L.) cultivation, both as industrial and food crop. The interest as food crop lays in the nutritional values of hemp seeds mainly related to their high-quality oil and proteins contents. As reported by Amaducci et al. (2015), hemp fibre can also be used as reinforcement in composite materials, to produce insulation mats, car interior panels, and requested in bio-building sector to form concrete too. The possibility to cultivate hemp for a dual purpose use could improve the farmer revenue. The information regarding the dual purpose hemp cultivations are poor and even more in Mediterranean environments. In this respect the present study evaluated the adaptability of Futura 75 hemp genotype under the Mediterranean conditions of Southern Italy (Sicily).

Perennial, no-food grasses have been proposed as the most efficient species for biomass production due to their natural resource use efficiency, agronomic, environmental and social benefits. Nitrogen requirement is a significant issue in intensive agriculture and greatly affects the energetic balance of crops. Hence, reduced nitrogen fertilizer by means of low input cropping systems could directly mitigate greenhouse gas emissions. In the present study long-term plantations of two perennial grasses (Arundo donax and Miscanthus x giganteus) grown in rainfed conditions under two nitrogen regimes were compared in terms of biomass yield and nitrogen use efficiency.

Perennial, no-food grasses have been proposed as the most efficient species for biomass production due to their natural resource use efficiency, agronomic, environmental and social benefits. Nitrogen requirement is a significant issue in intensive agriculture and greatly affects the energetic balance of crops. Hence, reduced nitrogen fertilizer by means of low input cropping systems could directly mitigate greenhouse gas emissions. In the present study long-term plantations of two perennial grasses (Arundo donax and Miscanthus x giganteus) grown in rainfed conditions under two nitrogen regimes were compared in terms of biomass yield and nitrogen use efficiency.