SCHLOT is based on the Norris Crop Value Model, which has been developed over more than 15 years, based on a combination of published Australian and International research, and unpublished research trials within Australia and overseas.
The model defines the ‘pre-harvest’ crop, in terms of the physical and chemical properties of crop components, and the respective yields. The model then looks at the impact on the yield and properties of each component of each step of the harvest process or machine interaction (eg. burning, topping, basecutting, feeding, billeting etc.).
Using this methodology, the model creates a very detailed description of the crop as well as the machinery ‘effort’ at each interaction to build a complete picture of the costs and loss of value (recoverable sugar) at each stage. It is important to consider each phase separately, as the outputs (crop properties) of each phase directly impact downstream phases (eg. cleaning efficiency and cane loss are both influenced by billet length, variety and pour rate).
SCHLOT takes into account the impact of pre-harvest burning on the physical and chemical properties of the crop. When a crop is burned prior to harvest, as well as destroying a lot of unwanted fibre (leaves), recoverable sugar is reduced. Based on published research from South America and South Africa and Australia, losses are related to heat of burn, and can exceed 6%. Burning also significantly increases the rate of deterioration of the cane after harvest. SCHLOT assesses the impact of the nominated heat of the burn on potential sugar recovery.
SCHLOT estimates the impact of topping on a crop by reducing the ‘yield’ of tops and green leaves under the nominated harvesting conditions and degree of lodging. In an even erect crop, cane loss is minimised and up to 80% of the tops will be removed with minimal cane loss. In a lodged crop, topping is usually ineffective. Topping parameters in SCHLOT are based on unpublished trials in Australia and elsewhere.
Gathering & Feeding.
Gathering and feeding an erect crop results in limited damage to the stalk as it enters the harvester feedtrain. The more heavily lodged the crop, the greater the damage: this impacts on billet quality, losses and rate of deterioration.
Every time the stalk is cut, juice is lost. Because juice is stored in the stalk at above atmospheric pressure, the juice actively escapes from each cut. As such, ratio of juice lost:fibre lost is higher than the ratio of juice:fibre in an uncut stalk. Because of this, billeting not only results in a loss of total mass, but also increased fibre%cane and reduced Brix/Pol in Cane and CCS. As well as the immediate loss of sugar through billeting, juice begins to deteriorate on exposure to oxygen – the shorter the billets, the more exposure, and the faster the deterioration. Similarly, the greater the damage to billeted cane, the higher the immediate losses and higher the higher the rate of deterioration. Hot weather seriously exacerbates these problems.
Based on BSES Chopper test rig work, an immediate total mass loss of up to 10% can occur with “10 blade” choppers at short billet length settings, with even greater losses with “12 blade” systems. Subsequent BSES research, and recent International research has found that actual lost CCS (tonnes CCS / ha) is up to double this.
Cane loss through the extractor is widely recognised as the largest source of loss to the industry in green cane, and can be significant in burned cane. Cane loss is impacted on by the amount and characteristics of leafy trash, pour rate, billet length and billet diameter, and of course, fan speed. In a particular field at some point in time, pour rate has more effect on the trashiness of the cane going to the mill than any other factor, however conditions (rainy v’s dry) and crop characteristics (trashiness and clinginess of trash) have very major impact on actual trash levels in the cane being sent to the mill.
SCHLOT uses data from large numbers of Australian and International harvesting trials to develop relationships between all these factors, and for different harvesters. This allows SCHLOT to better assess what will really happen when something is changed under given crop and field conditions.
Bin-weight is a major factor in harvesting costs, and the cost to the mill of transporting cane is also one of it’s biggest costs. Low bin-weights increase costs, however across the Industry bin-weights are generally reducing, despite reducing billet lengths. SCHLOT uses relationships developed from trial data to predict bin-weight based on a number of factors, including varietal characteristics, billet length and anticipated trash levels in the bin.
The grower is paid by the miller, based on the CCS of the delivered cane, minus a nominal crushing fee of four units of CCS. The CCS formula was initially developed for hand-cut cleaned green cane. Higher trash levels artificially inflate recoverable sucrose, as well as reduce the processing rate and recovery of both the milling house and the boiling house. SCHLOT uses the standard CCS analysis formulas on the product which is assumed to relate to different harvesting settings, to determine farmer payment. SCHLOT then used a series of other research findings to determine the impact of the different cane products on mill performance and probable recovery, as well as probable molasses production. Transport costs, milling rate, and the value of sugar and by-products impact on mill profitability
SCHLOT can be utilised by the mill in communication with harvesters and growers to assist in the management of the value chain, including allocation of bins.