Seawater desalination for crop irrigation — A review of current experiences and revealed key issues

• Seawater desalination for sustaining irrigated agriculture is an alternative water source in Spain and Israel.
• The use for crop irrigation is limited by its high cost when compared to other conventional water supplies.
• Agronomic issues should be considered to avoid unexpected adverse effects on agricultural productivity.
• Blending, management modelling, and on-farm technical means may mitigate these agronomics risks.
• Specific quality regulations are required for desalinated seawater use in agriculture.

Increasing water scarcity in arid and semiarid regions is driving the demand for non-conventional water resources in irrigated agriculture. Seawater desalination for sustaining agricultural production is being reported as an alternative water source in some Mediterranean countries. It represents an abundant and steady water source which effectively removes the climatological and hydrological constraints. However, first experiences are highlighting that certain important issues can become a barrier to its spread for crop irrigation. First, the high-energy requirement is still an essential feature of seawater desalination, leading to production costs several times higher than other agricultural water sources. Moreover, the high greenhouse gas emissions linked to the intensive use of energy could exacerbate climate change. Additionally, there are important agronomic concerns related to the lack of desalinated seawater quality standards; which can cause risks for both crop production and the soil environment if not properly managed. Specific quality regulations for desalinated seawater production, blending and management modelling, on-farm technical means and water and soil monitoring may mitigate these risks for crop irrigation. This paper reviews current irrigation experiences with desalinated seawater and analyses the most important questions to be considered, with a particular focus on the agronomical aspects.