How combine harvesting of green cane billets with different levels of trash affects production and processing. Part I. Field yields and delivered cane quality

New refineries in Louisiana, USA are requesting Louisiana sugarcane factories to deliver very high pol/very low color (VHPNLC) raw sugar with low ash concentrations. This higher quality raw sugar will allow both growers and factory processors to share economic premiums from the new refineries. A comprehensive factory trash trial was conducted in Louisiana to determine how different speeds of the extractor fans on two combine harvesters (John Deere 3500 and 3510 models) affect trash levels of green billets from L 99-226 commercial sugarcane variety (ripener treated) as well as upstream and downstream processing. Fan speeds of 1050, 850 and 650 rpm were studied on Days 1,2, and 3 (20-22 Nov, 2010), respectively, at a constant ground speed of 3.5 mph. Sufficient cane of each treatment (24-27 truck loads) was harvested and processed each day to purge the tandem mill of other cane and to process the selected cane for a total of -30 min. Trash tissues, prepared cane, and bagasse samples in the front end were collected and analyzed. Percent extraction and processing rates were calculated. Total trash levels (growing point region or top stalk + green leaves + brown leaves) were 12.1, 18.9 and 22.7% for the 1050, 850, and 650 rpm fan speeds, respectively, and significantly (P<0.05) different. There was extra trash than the hand-cut field cane at 850 and 650 rpm because of (i) slight layers of mud on the trash adding to the weight and (ii) weedy plant material. Most cane quality and processing parameters, including fiber, soluble solids, pol sucrose, purity, percent extraction, imbibition, processing rate, and mud volume became progressively worse with increased trash levels and decreased fan speed. Net proceeds to the grower were optimal for both growers and processors at the 850 rpm setting. More data are still needed for L 99-226 and other varieties, especially early in the Louisiana processing season when trash levels are considerably higher.