VALIDATION OF BEST PRACTICE HARVESTING PRINCIPLES IN THE PLANE CREEK, BURDEKIN AND HERBERT MILL REGIONS

A study by McKinsey Consulting in conjunction with sugar industry representatives concluded that there were significant gains to be made from the implementation ofharvesting best practice (HBP). HBP identifies that high fan speeds are a major source of cane loss and that reducing harvester pour rate reduces extraneous matter (EM). Therefore, lowering fan speeds will reduce the loss of sound cane and reducing pour rate will keep EM levels low. A series of trials testing different combinations of fan speeds and pour rates were done in the Plane Creek, Burdekin and Herbert mill regions in the 2002 season to test these concepts. Briefly, the green cane harvesting trials supported the HBP recommendations. Increasing fan speed increased cane loss and increasing pour rate increased EM (as inferred by fibre % in the cane supply). Interestingly, the trials also found that increasing pour rate increased sugar recovery. In green cane trials, best returns to the grower were from low fan speed treatments (at either high or low pour rates). Low pour rate combined with low fan speed gave the cleanest product with low losses but increased the cost of harvesting. High pour rates and low fan speeds kept losses low and reduced the cost of harvesting, but reduced bin weights because of increased EM content. The burnt cane trials did not show the same effects of EM as green cane. Increasing pour rate increased tonnes harvested in the burnt trials but did not affect CCS. There was evidence of a very slight increase in EM with increased pour rate; however, sugar yield also increased with increasing pour rate indicating that the increase was due to more than EM. Increasing fan speed increased losses of sugar in the burnt cane and returns to the grower were greatest from the fans off treatments in three of the five burnt trials.