By Peter Hill
ADAPTED forage harvesters are emerging as the most likely candidates for commercial harvesting of short rotation coppice in the UK.
Specialist harvesters that either cut only or cut and chip are widely used in Swedens extensive coppice-growing industry. But these would represent a big investment risk for growers or contractors in the UK, given the small acreage of coppice currently grown here for energy use.
Trailed and self-propelled forage harvesters, on the other hand, are already widely used and have proved effective in Forestry Commission trials. Short rotation coppice would provide additional work for such machines.
"This suggests that contractors would be able to charge lower hourly rates than if they were using specialist short rotation coppice harvesters working more limited hours a year," says Richard Deboys, technical development forester. "But it is also possible that growers themselves could use cheaper equipment – we briefly tried a trailed forage harvester with maize attachment at two sites this year and it worked reasonably well."
A Claas 695 Mega was among the machines demonstrated at Hunstrete near Bath last week, where Brian Maggs grows 10ha (25 acres) of short rotation coppice. The machine is standard other than for the specially developed coppice harvesting attachment which has twin saw blades and four feed rollers, and a horizontal roller to encourage cut material to feed-in evenly. The forager also needs a hydraulic drive system to power the attachment.
"Beyond that, all we do is remove six sets of blades from the chopping cylinder, as you might for maize," says Claas UK product manager Trevor Tyrrell. "We then get a chip length of 28mm or 35mm depending on the feed roller setting, and an output, in fresh weight terms, of up to 70t/hour. In other words, we are looking at clearing six to 10ha (15 to 25 acres) a day cutting two rows at a time."
At an anticipated price of between £25,000 and £30,000 for a coppice harvesting attachment, contractors will still need a fair workload to get a pay-off.
Making its debut at the Forestry Commissions demonstration was this tractor-mounted coppice harvester. A new version of Salix Maskiners "bender" harvester, it is mounted on a JCB Fastrac 155-65 with a 13cu m container on the back. The harvester features a long length of unsupported saw-chain designed to cope with different sizes of material and enable it to operate in the snow. Two large feed-in chains grab the sawn material and draw it into the chopping rotor and feed rollers.