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Pre-harvest burning persisted as the standard practice until the early 1980s when some growers began
to experiment with mechanical green cane harvesting and associated trash blanketing. In the Burdekin
region and New South Wales the crop is predominantly burnt prior to harvest. The percentage of
burnt cane harvested in the Burdekin region was 94.3% of 8,225,415 tonnes and New South Wales
92% of 2,174,886 tonnes in 2007 respectively. This is substantially higher than the industry average
in 2007.
2.1.3 Green Cane Harvesting
Green cane harvesting and associated trash blanketing involves harvesting the sugarcane green and
separating the dry and green leaf and tops from the cane. The aim is to minimise the amount of trash
harvested with the cane and allow the separated material to fall to the ground to act as a protective
trash blanket.
Machine design elements have to be changed to meet the requirements for harvesting green cane
when compared to burnt cane. The two most important points are that the volumetric capacity of the
machine must increase and the feed efficiency must increase so that choking or glut feeding is
minimised.
The use of this trash blanket as an organic mulch considerably reduces the level of soil erosion and
preserves soil nutrition for crop growth. It also helps to prevent weed germination, reducing the need
for herbicides. The agronomic benefits of trash blanketing, combined with greater harvesting
flexibility in wet weather, prompted the development of new technology.
However, districts with high yielding one-year or two-year crops such as the Burdekin and northern
New South Wales have largely avoided green cane harvesting because of harvesting difficulties and
agronomic constraints. Green cane harvesting has expanded gradually since the 1980’s, reaching
70.5% of the total crop harvested (34,125,022 tonne/cane) in 2007. The percentage of green cane
harvested in the Burdekin region (5.7% of 8,225,415 tonnes) and NSW (8% 2,174,886 tonnes) is
substantially lower the industry average.
2.1.4 Whole-of-Crop Harvesting
Diversification from ‘traditional’ sugar production within the industry has focused on production of
renewable energy from ethanol or electricity co-generation (Keating et al. (2002); Sutherland (2002)).
Undertaking these ventures entails new challenges for the traditional organisation of the sugarcane
supply chain.
Green cane harvesting leaves large amounts of trash (sugarcane dry and green leaves, and tops) for
energy purposes. A significant increase in recoverable energy is achievable by incorporating a
proportion of the trash in the cane supply, and separation of that trash at the mill prior to milling.
The dry and green leaves and tops represent about one-third of the total mass for commercial sugar
cane. Dry leaf trash has about double the net heat energy of bagasse and about three times that of
green leaves and tops. Hence, the dry leaf component is a significant energy resource and can
represent a significant energy capture.
Typically, the two strategies used for whole-of-crop harvesting are green cane harvest with all
material (cane and trash) transported to the mill and conventional green cane harvest with post
harvest collection (baling). Typically, the additional fuel sourced from either of these two strategies
is used to fuel co-generation plants. Green cane harvest with all material (cane and trash) transported
to the mill is the system with the closest synergies with the Mallee biomass harvesting system.
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