Harvesters for short rotation coppice: current status and new solutions

Abstract

Mechanization in the harvesting of short rotation coppice on farmed land is a prerequisite for the expansion of short rotation coppice cropping. Existing harvest lines can be classified as log, bundle, bale, or chip lines; the latter are widely considered the most economical. Despite the development of more than 20 different harvesting machines and assemblies for chip lines in the past decade alone, only a few have progressed beyond the prototype stage. In addition to special mower tools already available for conventional forage harvesters, there is a great need for low-cost tractor-mounted chip harvesters. Therefore, a novel working principle for a mower-chipper was developed and tested. In contrast to most other solutions, the trees remain in an upright position while mowing and chipping. The harvest machine has a compact single rotor bearing a circular saw blade with a diameter of approximately 1000 mm. Knives arranged radially are attached to the saw and offset above the disk with spacer blocks. To ensure even feeding of the mower-chipper unit, numerous passive and active machine elements were tested to find a reliable solution for practical application. With the investigated harvester, trees with stem diameters up to 15 cm and 10 m in height could be successfully harvested at very promising working speeds of 3–5 km/h. The Class P45 wood chips produced satisfied the CEN/TS 14961:2005 standard.

Keywords:

• short rotation coppice
• poplar
• willow
• black locust
• harvest
• mower-chipper

Acknowledgement

The project was funded by the Federal Ministry of Economics and Technology, Germany.