Analysis of irrigation systems and irrigation strategies for durum wheat in Tunisia

Abstract

To help identify an irrigation system and irrigation strategy to improve durum wheat production in the context of water scarcity of Tunisia, the PILOTE (operative water balance and yield estimation) model and the RAIEOPT (furrow irrigation) model are coupled. The first step was to choose the most efficient surface irrigation system (SIS) with its irrigation strategy. On the basis of field experiment data, an economic-optimization model allows the identification of the best SIS with its irrigation strategy for conditions of water scarcity in Tunisia. The furrow system with an inter-furrow spacing of 1.5 m and a strategy which consists on irrigating when the soil water reserve is 80% depleted are selected by the optimization model. Using “deficit irrigation” principles which establish a ratio between the amount of water applied to a given crop and a economically acceptable target yield value, irrigation strategies for sprinkler and the selected SIS are identified. RAIEOPT–PILOTE coupling is used to perform this analysis for SIS. The results of the simulations, based on climatic data spanning the last 20 years, raise questions about the suitability of sprinkler irrigation method for clay soil conditions in Tunisia. This paper also aims to contribute to future economic studies that will take into account social constraints. This study should allow managers to choose between sprinkler irrigation methods and SIS modernization.