Towards a more sustainable, water efficient protected cultivation in arid regions

The first step towards a more sustainable, water efficient greenhouse is made through the application of soilless culture. Numerous studies have shown that separating the root zone from the ground increases water efficiency up to 5 times since the process of irrigation is well controlled. Monitoring of the irrigation water and the drain water is an important aspect when applying this method. The ultimate system in terms of water saving is a closed greenhouse. No air exchange between the greenhouse air and the ambient is needed so no water is lost. Using a dynamic simulation model which acts as a virtual greenhouse, the operation of the Pad & Fan system and the closed greenhouse is evaluated under climate conditions in Riyadh. Water consumption is reduced by 95% and biomass production is increased by 75% due to the increased carbon dioxide level and the optimal climate. Almost 4 GJ of cooling is needed annually with a maximum cooling capacity of 650 W for the closed greenhouse.