Area determination of solar desalination system for irrigating crops in greenhouses using different quality feed water

• Solar still is employed to produce water.
• Different quality feed water is used.
• Two methods were used to calculate evapotranspiration.
• The water productivity from solar still is greater than crop water requirement.

The aim of this study was to present an alternative means of procuring fresh water from low-quality water sources to meet crop-water requirements (CWR) in greenhouses. A solar still was used in field experiments to desalinate three types of water: seawater, ground water and agricultural-drainage water. Three multiple linear regression models were derived, with an average coefficient of determination (R2) of 0.90 for the prediction of water-productivity capacity (MD). Two methods were used to estimate the CWR of greenhouses: the adapted Penman-Monteith (A-PM) method and the Fernandez (F) method. The R2 for the two methods was 0.95. The three water-productivity measurements were compared with the water requirements throughout the year to determine the required area of the solar-desalination system. The results indicated that the A-PM method can be used to estimate the CWR of crops grown in greenhouses. Generally, MD exceeded CWR throughout the year, and the average MD of the water types was 4.79 L/m2/day. In addition, the average CWR values obtained using the A-PM and F methods were identical (1.88 L/m2/day). The water produced by 1 m2 of the solar-still system was also found to meet the CWR of about 2 m2 of greenhouse. As the system's MD exceeds the CWR of a greenhouse, the proposed solar-desalination system is clearly able to meet greenhouse CWR.