Geothermal water in greenhouses in Tunisia : use of computers to control climate and fertigation with cooled geothermal water

Abstract

In Tunisia, geothermal water is used for heating and for irrigation when cooled to appropriate temperatures. The greenhouse sector is developing rapidly albeit under severe climatic conditions. Yield is still far from optimal. The use of climate computers would greatly facilitate further development of the sector. A brief description of the constituents of climate control systems is given and the advantages and disadvantages are discussed. The need of reliable, yet flexible systems is stressed. Climate computers can also be used to control fertigation in greenhouses and tunnels. The high content of some undesireable salts must be dealt with and inexpensive, reliable fertiliser blenders are suggested. An account of the chemical composition, especially macro-nutrients, of some wells in Kebili region in Tunisia is given and discussed with reference to the literature in order to facilitate solutions to the problems associated with usage of cooled geothermal water for irrigation.