Along the Mediterranean countries, water scarcity is a structural problem. In the Southest of Spain water shortage is becoming more acute, specially in the agricultural sector. In these areas the cultivation of citrus fruits is very important but those are irrigation, intensive crops with important water requirements. In order to optimize available water offer and rationalize the demand management an increase of the efficiency of existing irrigation systems could be achieved by the improvement of irrigation scheduling techniques. During the last years, irrigation systems have undergone a modernisation process, the majority of which implied the change of surface irrigation to drip irrigation systems. These changes have been promoted both by national and regional administrations and farmers. However, the adoption of drip irrigation has not involved an adequate irrigation management and thus, these irrigation facilities have not reached high values of efficiency, as compared to the potential efficiency of drip irrigation systems. An adequate irrigation scheduling is necessary in order to increase the efficiency values mainly avoiding infiltration water losses and applying only the water required to meet crop water needs. Traditional irrigation scheduling is based on a soil water balance model as the proposed by FAO. This methodology has proven to be partially accurate for fruit trees. For this reason is important to assess some possible alternatives or complements to the FAO model. Finally, the application of several systems of irrigation scheduling for citrus trees based on water content gauges has been studied. Some results, advantages and disadvantages of these systems are analyzed.
