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1.3 Supply Areas
1.3.1 Supply areas
Mallee System
Since the early 1990s almost 13,000 ha of mallees have been established in WA but there is potential
for expansion into other areas of the wheat/sheep zone in southern Australia (see Figure 1.1). The
mallee in WA is the largest resource available for start-up industries and market development but it is
relatively scattered and not properly quantified at present. The two most concentrated centres of
activity are in the Central Wheatbelt (the Shires of Dalwallinu, Mount Marshall and Koorda) and the
Upper Great Southern (Shires of Narrogin, Cuballing, Wickepin, Wagin and Kulin) (URS, 2008).
Each of these regions could possibly supply 20,000 to 50,000 green tonnes per year on sustainable
basis. This figure could be properly determined with a GIS-based inventory and site assessment.
The total land area in southern Australia that may be suitable for expansion of mallee and other short
rotation woody crops (see Figure 1.1) is summarised in Table 1.5(a). There is potential for expansion
of the model into central Queensland, using appropriate species for that environment. The estimates
in the literature of potential woody biomass production from the land area in Table 1.5(b) vary
widely, depending upon the assumptions of the proportion of land area that will be planted and the
growth rates.
For this description of potential biomass production, we have followed the example of Peck et al
(2011), where it is recognised that mallees need to be big enough for economical harvesting, in that
there must be about 20 green tonnes or more of biomass per kilometre of row to achieve economical
pour rates through the harvester. It is not the maximum mean annual increment that determines
potential production, but the mean annual increment over the whole rotation from one harvest to the
next. This can often be less than the maximum MAI, especially in the lowest rainfall zones where
annual growth rates are observed to decline part way through a rotation when rotations of seven or
more years are required to achieve harvestable yields.
The proportion of land area that is planted to mallees or other crops is a very broad assumption, but
the assumptions in Table 1.5(c) are that a small proportion of land will be utilised because farmers
will opt to use mallee as a diversification of the farm enterprise, not as the principal farm enterprise.
Potential production is not adoption. Estimates of future biomass production made by the Future
Farm Industries CRC, taking an industry development perspective from the biomass processor side,
rather than starting from the area of land under agriculture, indicate that in the southern states, about
160,000 to 170,000 hectares of land may be under mallees, producing about 2.6 million green tonnes
per year, by 2025 – 2030 (FFI CRC, 2010). The potential to produce significant quantities of biomass
exists due to our large land base, but development of processing industries will strongly influence
how quickly this potential is realised.
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