Upsized harvesting technology for coping with the new trends in short-rotation coppice

Since 2003, Italian farmers have planted over 4000 ha of short rotation coppice (SRC), established almost exclusively with poplar clones and harvested every second year. Currently, there is a strong interest towards extending rotation age and diversifying tree species, in order to increase product quality and to exploit less fertile sites. That implies harvesting larger and harder trees, which may prove challenging for existing harvesting units. This study offers preliminary data on the productivity, efficiency, and cost offered by two new harvesting units, specifically designed for handling larger trees. These were a Krone Big-X forage harvester fitted with the HTM header and a John Deere 7400 forage harvester fitted with the Biopoplar header. The machines were tested on poplar, robinia, and willow. Gross machine productivity ranged from 15 to 50 green tonnes per scheduled machine hour. The actual harvest rate (the productivity of cutting and chipping only) reached 60 t h-1. Both harvesters offered reasonable harvesting costs, generally in the range of 14 EUR t -1 (1.8EUR GJ -1). Both machines were pre-commercial prototypes and their performance will be further improved in the eventual commercial versions. The study also highlighted the excellent performance of robinia, which proved superior to poplar on the same fields, and reached yields in excess of 15 odt ha-1year-1. A further advantage of robinia is the low moisture content at harvest, which may help solving the fuel moisture issues inherent to the current single-pass cut-and-chip harvesting systems.