Alleviating water shortages by decreasing water footprint in sugarcane production: The impacts of different soil mulching and irrigation systems in South Africa

Abstract

Identifying ways and practices to alleviate water scarceness is an important policy issue across sectors, particularly in the agricultural sector in arid countries. The present study examines how water scarcity can be alleviated by decreasing the water footprint of sugarcane production using different soil mulching and irrigation systems in South Africa. The study also quantifies the economic benefits of reducing blue water footprints. The MyCanesim model and water footprint assessment methodologies were employed to estimate blue and green water footprints under the different systems in the Malelane region of South Africa. The findings reveal that blue water consumption for sugarcane grown with a thick mulch cover was substantially lower than for that grown with a light mulch cover. The difference was larger for centre pivot-irrigated sugarcane than for subsurface drip-irrigated sugarcane. The blue and total (blue plus green) water footprint values for crops grown with a thick mulch cover were only marginally lower than for those grown with the light mulch cover. The blue water footprint for subsurface drip-irrigated sugarcane was 8–10 m3/t lower than for centre pivot-irrigated sugarcane due to its higher application efficiency. The economic productivity of blue water usage for subsurface drip-irrigated sugarcane was higher than for centre pivot-irrigated sugarcane crops. In addition, the economic water productivity of blue water usage for crops grown with a thick mulch cover was slightly higher (5%) than that of those grown with a light mulch cover under subsurface drip irrigation. The findings support the notion that water-use efficiency in sugarcane production can be improved and the water footprints reduced by implementing more efficient irrigation systems, by covering the soil with a thick mulch cover to limit evaporation, and by implementing effective irrigation scheduling.