More crop per drop: Improving our knowledge on crop water requirements for irrigation scheduling

Abstract

South Africa is a dry country facing climate change, population expansion and economic growth, resulting in increasing water scarcity and competition for water. The irrigated agriculture and forestry sectors have been allocated approximately two thirds of the surface water resources of the country. Dependence on irrigation for the production of key crops such as vegetables and fruit is high, due to low, erratic or unreliable rainfall in many parts of the country, combined with the high value (export potential) of those crops. However, there is essentially no more water available to allocate to irrigation. Consequently, the only option is to improve knowledge on crop water requirements and associated irrigation scheduling, thereby enhancing water productivity and producing more ‘crop per drop’. Furthermore, while plantation forestry in South Africa is critical for timber and fibre production, income generation and job provision, these come at an environmental cost, notably the impact on water resources. The ongoing spread of invasive alien plant species also reduces water availability in the country. Gush provides a technical perspective on quantifying the water use of different agricultural and forest land covers. The potential impact and applications of this information are discussed from a water resources management perspective.