Actual harvester extractor cane loss: the elephant we can no longer ignore

Since mechanised harvesting of sugarcane became established in the 1970s, farmers, manufacturers, and researchers have been attempting to improve harvester performance and optimise harvest efficiency. The move to green-cane harvesting and the introduction of pneumatic extractor systems on sugarcane harvesters both significantly increased cane loss. Protocols were developed for measuring actual extractor losses. Whilst “averaged” actual extractor losses are typically close to 10% of the crop yield, machine settings, field conditions and varietal characteristics give high variability in cane loss at nominal machine settings. Field and workshop trials demonstrate that, with modern harvesters, the visible recovered cane pieces, “shrapnel”, are often much less than 10% of the actual cane lost through the extractors in normal operation. Outside the Australian industry, the typical protocol for determining losses through the extractors is to collect and weigh this cane “shrapnel” after harvest, assuming it represents 100% of the loss. When compared with the visible losses associated with gathering, pickup, basecutting and spillage losses, shrapnel extractor losses are usually considered minimal. In over 30 peer-reviewed papers published over the last decade, reported (visible) extractor losses seldom exceeded 1.5% of yield and were considered of little concern relative to other visible losses. Significantly, manufacturers use visible losses in the discussion of cane loss and cane-loss monitors fitted to some harvesters are calibrated against these shrapnel measurements. This monitoring of visible losses then drives an “alternative reality”, where harvester extractor losses are considered to be low, but are actually highly variable and often much greater than all other harvesting losses combined, with an associated impact on industry profitability. In the papers reviewed, the knowledge of the key drivers of cane loss and the lack of understanding of the interactions within the cleaning system were alarming. Fundamental parameters were not recorded, with many researchers and reviewers demonstrating a limited understanding of the cane loss process or the parameters that impact cane loss. International standards must be developed for the measurement of actual cane loss, and both commercial and research communities must use these standards in monitoring cane loss; “visible loss” data is of no technical value and is a dangerously irrelevant measurement. Further research is warranted to accurately measure and manage actual cane loss, ensuring that commercial cane loss systems display actual cane loss rather than an irrelevant surrogate.