Geothermal utilization for heating, irrigation and soil disinfection in greenhouses in Tunisia

Abstract

There has been a rapid development of greenhouses heated by geothermal water in the southern part of Tunisia. This evolution has placed the country third throughout the world with 80 ha after only 11 years of development. The government emphasizes the importance of this agricultural activity which gives the opportunity to produce and export to Europe during the cold period. Greenhouses which use geothermal water both as a source of heat and irrigation are considered among the most complicated systems in agriculture. Planning is needed before creating a geothermal greenhouse project. Several parameters should be taken into consideration in order to avoid high risk and failure of the project. Different important aspects will be discussed in detail such as site choice and organization of the greenhouse project, as well as temperature and flow regulations. Water equilibrium between heating and irrigation in oases and greenhouses will be presented in order to avoid loss of geothermal resources, very important in this arid zone. The technical use of geothermal water in irrigation and fertilisation for vegetables grown in greenhouses will be presented. A new method, developed in Tunisia, using geothermal water for soil disinfection against nematodes is presented. Geothermal greenhouses created close to the oasis present numerous advantages to this system.