Potential for Sugarcane Production Under Current and Future Climates in South Africa: Sugar and Ethanol Yields, and Crop Water Use

Abstract

Spatial information on crop productivity and resource use are required to enable efficient sugarcane production with limited resources and under a changing climate. The objective of this study was to estimate biomass, sugar and ethanol yields for highsucrose (HS) and high-fibre (HF) sugarcane cultivars for current and future climate in water limited South Africa. An upgraded version of the Canegro sugarcane model, calibrated for a hypothetical HS and HF cultivar, was used to simulate biomass component yields for 1,986 agro-climatic zones. Ethanol yields were calculated from simulated biomass fractions and theoretical conversion efficiencies. Historical daily weather data for 1971-1990 were used to represent the baseline climate, while daily weather data generated from three global circulation models for 1971-1990 and 2046-2065 were used to project future changes in climate. Simulations show that the HF cultivar produced higher (15-35%) biomass and ethanol yields than the HS cultivar, but also used slightly more (~4%) water. Climate change is projected to increase dryland yields for both cultivar types (8-19%) Irrigated yields will not change much in current high potential areas (1-5%), given adequate water supply, while yields could increase substantially in current cool areas (~20%). Water and irrigation requirements are expected to increase (9-15%) under a future climate. New areas could be become suitable for irrigated and dryland production. The information produced in this study can be used to assist decision-making for: (1) optimizing production and processing processes; and (2) the development of sustainable greenfield projects in marginal areas of South Africa. Response to Reviewers:The reference style format of the journal is not followed. Pl see a recent publication and revise the references in reference section. CO2 should be corrected all over the ms.I have edited references to comply with journal format. Acronym CO2 was corrected throughout.