LAUSR

Abstract Desalination is becoming a competitive alternative for supplying quality water to irrigation districts in dry areas. However, its acceptance level among farmers is often low due to its higher price, the need for additional fertilization, and the misconception that it would negatively affect yield and crop quality. This work presents a decision support system that would help them to make irrigation management decisions regarding the optimal combination of saline and desalinated seawater (DSW), which would provide maximum economic profit. The model has been specially designed for Mediterranean greenhouse cropping systems. The proposed model was validated by applying it to a real watermelon crop which was experimentally monitored. A sensitivity analysis was then conducted in order to analyze the effect of different limiting factors on the optimal combination of water and the optimal profit for farmers. The application of the model to the case study demonstrated that it is profitable to use a blend of DSW and brackish water for irrigation of greenhouse crops. Despite the higher cost of the DSW, the economic optimum was achieved for higher DSW fractions than those which are used today. This sensitivity analysis has demonstrated that brackish water salinity, irrigation uniformity and crop tolerance are relevant factors that affect the optimal combination decisions. This work may encourage farmers to accept desalinated water.