| Abstract | Harvesting Best Practice (HBP) recommends that harvesters maintain pour rates of 80-90 t/h,
depending on make and model, and recommends extractor-fan speed guidelines that ensure
minimal cane loss with low extraneous matter (EM). Exceeding the recommended pour rate
overloads the cleaning capacity of modern harvesters and increases EM in the cane supply.
To attempt to counterbalance the EM issue, it is usual to increase fan speeds above those
recommended, resulting in greater cane loss. Use of HBP recommendations across the
industry is low and full HBP adoption would substantially increase industry revenue. To
address this, 43 replicated harvesting trials and workshops were undertaken in the 2017
harvest season across 12 sugarcane regions between Maryborough and Mossman. The
performance of settings recommended by HBP were compared with each harvesting
operation’s standard practice by assessing yield, CCS, bin mass, EM, fibre, sugar loss and
revenue. To highlight the strong relationship between cane loss and excessive pour rates and
fan speeds, treatments with higher pour rates and fan speeds and lower pour rates and fan
speeds were also trialled. Results were presented to each harvesting group to inform their
decision-making and promote HBP adoption. Cane loss, production and revenue data from 28
replicated and randomised trials were analysed to identify differences between industry
standard harvesting practices and those recommended by HBP. We found that harvesters are
typically operated at ground and fan speeds that are on average 1 km/h and 95 rpm above
those recommended. The higher ground speed delivered an additional 22 t/h of cane into the
machine on average but overloaded the cleaning capacity of the harvester. While the higher
fan speed helped to remove the additional EM entering the machine, it also removed additional
cane through the extractor with most being disintegrated, making it invisible to stakeholders.
Testing indicated that mean sugar loss out of the extractor was increased by 0.15 t/ha
compared with HBP settings, while there were no significant differences in EM or bin mass.
Due to the additional cane being lost, less cane was delivered to the mill per hectare. Mill
results across all trials identified that mean cane and sugar yields for the recommended
practice were 5 t cane/ha (5.4%) and 0.8 t sugar/ha (5.7%) higher than standard practice.
Neither CCS nor fibre levels were significantly different. The increased cane and sugar yields
generated by the recommended settings boosted mean total grower revenue by $220/ha,
equating to $173/ha after subtracting the additional harvesting costs (including fuel) and levies.
Extrapolating these findings across the Australian green-cane-harvested area, full adoption of
the recommended practices could deliver an additional 1.3 Mt of cane and 202,000 t of sugar
valued at over $86 million for industry ($57 million in additional revenue for growers alone). |
