BENCHMARKING CANE SUPPLY QUALITY IN THE HERBERT, BURDEKIN, PROSERPINE AND PLANE CREEK REGIONS

A SURVEY OF the quality of the cane delivered to the Herbert, Burdekin, Proserpine and Plane Creek regions was undertaken in 2015 to assess the quantity of extraneous matter (viz. dirt and roots, trash and tops) in the cane supply, as well as measure billet length and quality (viz. sound, damaged and mutilated). Extraneous matter was between 5.4% and 32.7% of the cane supply in the Herbert, Proserpine and Plane Creek regions and between 3.6% and 12.0% of the cane supply in the Burdekin. Tops were between 36% and 55% of the median extraneous matter in the cane supply and it was evident that harvesters are routinely not topping cane, even when it is erect. Billet length has continued to decrease since the early 2000s and it was estimated that 21%, 15%, 9% and 20% of the harvesters in the Herbert, Burdekin, Proserpine and Plane Creek, respectively, had installed 10-blade chopper systems, while at least 2 harvesters in the Burdekin have 12-blade chopper systems that produce a billet that is around 126 mm long. Median billet length was between 13–20 mm shorter than that expected from a harvester with an optimised 8-blade chopper system. It was estimated that approximately 93 900 tonnes of biomass, cane and juice, is lost during the billeting operations due to these harvesters not being optimised. It was further surmised that between 300 000 and 800 000 tonnes of cane is possibly being lost and not delivered to the mills, as shorter billets are more prone to loss in the extractor systems. Best fit regression models identified that dirt and roots, trash, tops, damaged billets and mutilated billets impact negatively on the CCS. Research is needed to quantify how these affect CCS and to develop strategies to assist harvester operators better harvest the cane crop to maximise the return to the entire value chain of the industry.