Whole Farm Harvesting Strategy Optimisation Using the Canegro Model: a Case Study for Irrigated and Rainfed Sugarcane

There are two conflicting trends to be considered when optimising crop cycles on a farm. While yield and quality increase as harvest age increases, longer crop cycles reduce the total annual area harvested, potentially reducing the farm's total production. Optimisation of crop cycles is a complex problem, which has to account for the dynamic impact of a multitude of agroclimatic and economic factors. The aim of this study was to demonstrate the use of the CANEGRO model and strategy analysis techniques to identify optimal harvesting strategies for two cases. Seven practical harvesting strategies were simulated for a 27 year period. Annual gross margins were calculated and different criteria of maximum profit and minimum risk applied to identify optimal strategies. Results indicate that, for the irrigated Tala valley scenario, maximum profits would be achieved when 60% of the total area under cane was harvested per annum. The optimal strategy identified for the rainfed Tongaat scenario was to harvest 52.9% per annum. This recommendation excludes the effect of the Eldana stalk borer. A sensitivity analysis showed that the recommendations at Tala valley were relatively stable and could absorb normal fluctuations in harvesting costs and the RV price. It was concluded that the methodology developed here is suitable for optimising harvest strategies and could be applied for other scenarios in the SA sugar industry.