DOES CANE YIELD, INFLUENCED BY NITROGEN FERTILISER RATES, AFFECT CANE LOSS DURING CUTTING?

摘要

Many factors such as field and crop condition, harvester set-up, and harvester configuration, have an impact on sugar loss, sugar quality and the amount of extraneous matter in cane delivered to the mill. Crop size also impacts on harvester pour rates and cane loss during cutting. Crop size, physical properties of cane, and stalk composition are, in turn, often influenced by fertiliser application rates. The objective of this study was to identify those cane properties affected by in-field nutrient management [nitrogen (N) in particular] and their impacts on cane loss during cutting. The physical properties of cane (stalk length and diameter, population density and hand-cut yield) were determined immediately prior to the mechanical harvest of cane in replicated plots that had previously received different rates of applied N: 0, 75, 150 and 225 kg N/ha. Cane loss during cutting was then determined at harvest by collecting all extraneous material extruded from the harvester (leaves, tops, trash and pieces of stalk). This was done using a standard 'tarp test' combined with high performance liquid chromatography (HPLC) as described by Whiteing (2013). Importantly, this method also allowed for capture of the 'invisible' cane loss (juice, etc.). The extruded material / residues from the harvest operation were collected, shredded and frozen for later determination in the laboratory using HPLC. As expected, increased N rates resulted in increased cane yields. The different N rates also influenced the stalk population (stalks per unit area), stalk size (length and diameter) and stalk weight. Preliminary results indicated that cane yield, affected in this instance by the amount of N applied, with a set ground speed, impacted on pour rate. As pour rate increased, the ability of the extractor fan to efficiently differentiate trash from billets decreased. This work will continue in the upcoming season.