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inconclusive result may have been due to the variable nature of seasons, in that summer or autumn
rain does occur, albeit unreliably, and autumn harvests sometimes occurred after such events.
In operations, harvest timing may be varied according to specific site conditions. Sites most sensitive
to harvest mortality will be those with shallow soil due to impeding layers in the soil or shallow
saline water tables. These sites would need to be harvested only in optimal seasonal conditions such
as spring and early summer. Sites on deeper soils and a history of sustained growth from year to year
will presumably indicate greater access to soil moisture and could be harvested at any time of the
year. Other sites may be suitable for harvesting in autumn if there has been some late summer or early
autumn rainfall.
Soil conditions and soil strength will also be a factor for the use of heavy machinery. Even with highflotation
undercarriages, machines will leave ruts at the wettest times of the year and the haulouts
working at high speed and with high payloads may be the worst offenders. The harvesters will spend
the majority of their time on the tree belts supported by the root mats around the mallees, but the
haulouts will range widely and cross concave slopes and creek lines repeatedly as they follow fences
to the nearest landing. Bogging is the worst case result for both farmers, who will be left to repair the
damage, and the harvesting contractor who will lose significant time.
The annual cropping programme in the paddock may also be a factor. Trafficking by harvesters and
haulouts will damage crops, and to a lesser extent, pastures. High value crops late in the season may
require mallee harvesting to be excluded altogether until after harvest. Precision guidance of mallee
machinery to restrict soil damage to defined tracks will help to minimise the impact on annual crops
and cropping soils.
Sugar System
Mill operating periods are aligned around optimal harvesting windows for sugarcane. This is driven
by three key factors. Firstly sugarcane quality (in terms of extractable commercial cane sugar) which
increases from winter, peaks in September and then declines with onset of the hot wet summer
season, when plant photosynthesis focusses on biomass growth at the expense of sugar quality.
Second the available mill processing capacity relative to sugarcane volume from the supply area.
Finally the risk of rainfall and wet infield conditions which will impact harvester and hauler access
and infield damage to the crop and future ratoons. The optimal harvest window will vary across the
industry but typically is from July to November. Variations within a mill area will occur based on
cane variety, soil type and topographical position. A rateable delivery system, where all growers
supply equal proportions across the season is in place to provide equitable access to optimal
harvesting windows.
1.5 Discussion and Recommendations
1.5.1 Discussion
Sugarcane and mallee systems have many similarities as outlined in this chapter. They both represent
high volume, relatively low value crops, which require considerable processing and value addition to
meet the selected market. Both systems have significant harvest and transport requirements using
specialised equipment. In both cases delivered cost is high relative to the market price.
Sugarcane industries have spent many years researching and refining their crop production systems
and associated harvesting and transport arrangements. While sugarcane farming systems have
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