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Low annual tonnages and low pour rates cause costs to rise significantly, and when the industry is
mature and harvesters work two shifts a day at higher pour rates, costs may fall as low as $13 per
green tonne at the paddock landing. Estimates of a shunt truck as the intermediate form of transport
have not been modelled as part of this project but indications are that this operation would add $3 to
$4 per green tonne for biomass loaded onto road transport trailers at a roadside landing about ten
kilometres from the harvester.
Proven systems robust enough to harvest mallee at full scale have not yet been demonstrated
commercially, hence the actual cost of harvesting is unknown. However, the theoretical costs are still
well above that of sugarcane harvesting per tonne.
The importance of harvest/transport costs on overall supply chain economics should not be
underestimated.
2.6.3 Discussion
At equivalent pour rates, the cost of sugarcane harvesting is less than half that of the estimated cost of
mallee harvesting. Actual costs of mallee harvesting are unknown. While yields per km of row are
similar to that of sugarcane, a mallee harvester’s speed while cutting will be about half that of cane
harvester. The installed power of a commercial mallee harvester will also need to be perhaps twice
that required for cane harvesting due to the energy intensive nature of wood chipping, and mallees are
a much more dispersed crop on a whole paddock hectare basis, which will add to infield transport
costs.
2.7 System Improvements
Sugar System
Over the past 30 years, the research and development activities within the harvesting arena of the
Australian sugar industry can be grouped into three distinct periods.
During the 1980’s, research and development was centred on performance evaluation of machines in
green cane harvesting with Ridge and Dick (1988), Stewart and McComiskie (1988) and Shaw and
Brotherton (1992) investigating throughput, EM and cane losses during cleaning. Ridge and Dick
(1988) also investigated dirt rejection by harvesters.
During the 1990’s, research commenced on the fundamental interactions between the crop and
machine components with Pearce (1994), Kroes and Harris (1994), Kroes and Harris (1995), Kroes
(1997), Schembri and Garson (1996), Norris et al. (1998), Norris et al. (2000), Hockings et al. (2000)
and Zillman and Harris (2001) investigating gathering, knockdown, feeding, basecutting, billeting and
primary cleaning systems. Research into improving feeding ability and performance in large green
crops continued into the 2000’s with Davis and Norris (2002a), Davis and Norris (2002b), Davis and
Norris (2003), Davis and Schembri (2004) and Whiteing and Kingston (2008).
Throughout this period ongoing cane quality (EM/Dirt) issues and cane losses were evaluated by
Linedale and Ridge (1996), Fuelling (1999) and Schembri et al. (2000). Whiteing et al. (2001, 2002)
undertook fundamental investigations into the effect of fan speed and pour rate on cane loss and EM.
In recent times the industry has been striving to improve the efficiency and productivity of its
sugarcane harvesting and transport practices. Over the past few years the research focus has been on
harvest system modelling (e.g. Higgins and Langham (2001), Antony et al. (2003), Higgins and
Davies (2004), Sandell and Prestwidge (2004)), harvesting best practice (e.g. Sandell and Agnew
(2002), Willcox et al. (2004), Muscat and Agnew (2004)), sugar losses (e.g. Davis and Norris (2001),
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