REDUCTION OF BIOMASS LOSSES IN MECHANIZED HARVEST OF PERENNIAL GRASSES: A SHORTCUT TO INCREASE THE COMPETITIVENESS OF ENERGY CROPS

摘要

Experimental trials across Europe have confirmed the high yield potential of perennial lignocellulosiccrops like miscanthus (Miscanthus x giganteus), switchgrass (Panicum virgatum) and giant reed (Arundo donax), andtherefore their great potential as bioenergy feedstock. However, the vast majority of information on productivity ofthese crops derives from plot experiments, while very little is know on the actual yields and biomass losses in amechanized harvesting system. In the present article we reviewed some field-scale studies on biomass loss inswitchgrass, miscanthus and giant reed carried out at the University of Bologna over the last few years. Theassessments were conducted in Bologna (Italy) in two contiguous 6-year switchgrass and giant reed plants, and in a 3-year miscanthus plant. Along with commercial machineries, a prototype that cut the stems in 30-50 cm portions wastested. Crop potential yield was determined through hand harvested samples collected across the fields concurrentlywith mechanical harvest. Miscanthus, giant reed, and switchgrass exhibited potential yields of 29.3, 24.6, and 16.9Mg ha~(-1), respectively. Biomass losses during cutting and baling using common farm machines were considerable,averaging 30% and 21% in giant reed and switchgrass over a 5-year period. Nonetheless, in the last two years wefound that simple adjustments to the harvesting machines along with appropriate agronomic strategies allowed toreduce losses massively.