Measurement of in-field sucrose loss by mobile refractometry : SRDC Final report BSS318

Abstract

A world-first mobile system to measure sugar loss during harvesting has been developed and successfully field tested. This sugar is lost in all parts of the field residue: trash, tops, smashed billets and juice extracted by the harvester cleaning system. Interaction with industry through focus groups and discussions across all sectors has been a key factor in ensuring that the system being designed addressed industry requirements and expectations. Initial work focussed on confirming that digital Brix refractometer analysis of liquid extracted from field residue provided a measure of sugar content of the samples. Laboratory analysis of 286 field residue samples compared Brix values of the liquid extract to the actual sugar content using HPLC analysis. This showed a strong correlation that paved the way towards developing a mobile system to measure harvesting losses directly in the field during harvest. A field-testing methodology to process field residue was developed whereby trash was collected, weighed, mulched, washed, blended and then placed in a juice press to obtain a liquid extract. A design concept for a mobile system was developed incorporating all the necessary equipment to collect, process and analyse field residue for sugar content in the field. The prototype system was built and rigorously field testing from far-northern Queensland to New South Wales over two harvest seasons with a further 265 samples collected and analysed in the field. Duplicate samples were frozen and later analysed using HPLC (highpressure liquid chromatography) that showed an even stronger correlation to sugar content than the preliminary work (R2 of 0.8225). Losses measured ranged from 0.15 t.sugar/ha to 3 t.sugar/ha with the value of cane extracted by the cleaning system exceeding $1000/ha on some occasions. Dozens of industry stakeholders, including BSES extension staff, productivity service staff, millers, growers and operators, were able to see the system in use, discuss the results and in some cases have hands-on experience using the new technology. There was a high level of acceptance and confidence in the results generated using the mobile prototype. Feedback from industry was positive as result of the ongoing communication of progress and results with stakeholders at every stage of the project. Data generated from field testing of the system has produced harvester performance curves for current harvesting technology that allow operators to balance the pressure to produce high bin weights against the cost of excess cane loss. Being able for the first time to provide accurate data on cane loss immediately during harvest proved invaluable with harvester operators being able to discuss information with researchers in the field and then modify their operation to make financial gains. The increased industry awareness of sugar lost during harvest should not only reduce losses but stimulate discussion and action to tackle some of the value-chain issues that act as barriers to adoption of harvesting best practice. This world-first system is a valuable tool to provide quality data for future harvesting research such as assessing the sugar losses associated with cutting short billets to increase bin weights or evaluating new harvesting technologies/retrofits.