Assessing the potential for improving mill area profitability by modifying cane supply and harvest scheduling : a South African study

In South Africa, cane is delivered to the mill uniformly over the milling season and across all supply areas. This delivery schedule does not exploit the cane quality patterns, represented by the 'recoverable value' (RV) of sugar, which show distinct regional trends, primarily due to climate differences and the resulting differences in agronomic practices. This study, which focused on the Sezela mill supply area, investigated the potential for improving mill area profitability by modifying cane supply and harvest scheduling to account for sub-region cane quality trends. Production and delivery data from mill weighbridge and cane quality databases was analysed for 2000 and 2001, to determine cane quality trends as well as the capacity and variability of cane deliveries through the season. Sub-areas likely to have similar patterns in cane quality throughout the year were delimited using weather data, and new curves for RV distribution were developed for these areas using the cane quality database. Various cane supply scenarios from these sub-areas were evaluated using a spreadsheet model developed during the project. Each scenario represented different start and end dates for cane delivery in each sub-area, and different rates of delivery during the harvest window. The results showed that, by breaking the mill supply area into homogenous zones and adapting allocation according to cane quality variations, total RV production could be increased by 1-5%. Furthermore, results showed that all growers (inland, hinterland and coastal) would improve their revenues under the scenarios tested. The implications of this new organisation for delivery allocation between growers within a sub-area, harvest operations at farm level and the cane payment system, are discussed.