Sugarcane productivity and water use in South Africa under a future climate: What can we expect?

Abstract

Reliable predictions of sugarcane crop response to climate change are necessary to plan adaptation strategies for the South African sugarcane industry. The objective was to estimate expected changes in sugarcane yields, water use and irrigation requirements due to climate change for existing and potential new production areas in South Africa (SA). The DSSAT-Canegro model was used to simulate dryland (non-irrigated) and fully-irrigated crops for 1967 catchments using actual weather data for the period 1971-1990 (past) and projected weather data (from three climate models) for the period 2046-2065 (future). Temperatures are expected to increase by about 2°C. Rainfall projections are less certain with a possibility of slight increases in annual total rainfall, especially in the northern parts of the industry. Most dryland yields are expected to increase due to accelerated canopy development and increased water use efficiency. Increases vary from 11% in current warm areas to 33% in current cool areas. Irrigated yields are expected to increase marginally (1-5%) in current high potential areas, while larger increases are expected for current marginal areas. Crop water use and irrigation requirements are expected to increase by 8% to 11%, respectively. Areas in northern Limpopo, north-eastern parts of the Eastern Cape, and high-lying areas in KwaZulu-Natal and Mpumalanga are likely to become suitable for sugarcane production as temperatures increase. A database was generated for areas in SA where sugarcane can potentially be grown. The database comprises estimated sugarcane yields, water use and irrigation requirements, at sub-catchment level, for the past and the future climate. The information should be useful for the planning and future management of sugarcane production in SA.