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important. If debarking is required this will provide some significant challenges as the high
bark/wood fibre ratio associated with small stems may result in the loss of a significant amount of
saleable wood fibre during the debarking process.
Chipping is an important step in the overall delivery process, as it converts the mallee into the
product received and used by the customer and increases bulk density, which acts to reduce
transport costs. Chipping can be conducted infield as an integrated operation with harvesting, or
at road side.
However, the nature of the mallee crop (very small, non-uniform and clumped stems, very low
tonnages per paddock hectare) precludes the direct adoption of existing forestry systems, although
there are proven machine components that might well provide a basis for the development of mallee
specific systems (McCormack et al. 2009).
The need for a mallee harvester was identified by the WA Oil Mallee Association which led to the
development of an original prototype in the late 1990s and early 2000s. The prototype harvester was
developed by Dumbleyung Engineering. Initially a second hand sugarcane harvester was purchased
by growers, but this failed to handle the mallee plants properly and components from this machine
were used in the work done by Dumbleyung Engineering. This work showed that a commercial
harvester would need to follow a single-row process that cuts the trees close to the ground, handles
the trees standing upright, and chips them in a continuous flow.
In 2008, Biosystems Engineering was appointed by the Future Farm Industries CRC (FFI CRC) to
design and manufacture a prototype mallee harvester.
The design approach is based on engineering principles and the premise that mallee can be harvested
in a manner different from traditional forestry methods. That is, mallee is considered a large forage
crop that lays between thin-stemmed crops such as sugarcane or coppice willow and conventional
forest plantation trees.
Typically, current European harvester systems are based upon modified forage harvesters from
agricultural machinery manufacturers. Unfortunately both the generally light weight construction of
the machines and the general feeding /chopping arrangements preclude their use in the larger, tougher
mallee.
Therefore, a new design was needed. A prototype was developed and incorporated the lessons learnt
from the previous prototype. Its layout is based on an implement attachment (harvester head) for a
utility tractor (Claas Xerion Saddle Trac).
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