The most widespread irrigation scheduling method is based on the determination of soil-water balance, which implies the estimation of crop evapotranspiration (ETC). Generally, ETC is calculated combining the measurements of potential (or reference) evapotranspiration (ET0) through meteorological stations with crop coefficients . The latter need regular updating by the farmer for each crop type and growing stage. One rather new approach is to obtain crop coefficients with satellite based radiation images, rather than by using time-costly manual field observations. Recently, D��Urso et al.  developed such a system within the framework of two European projects: Demeter (www.demeter-EC.net) and Pleiades (www.pleiades.es).
Access to the satellite data has become much easier and faster due to recent development with web-based access and due to improvements of sensor spatial resolution and accuracy. D��Urso et al.  report that satellite remote sensing is a mature technique, suited to be transferred to practical application for on farm, down to the plot, irrigation management.The other approach to irrigation scheduling entails the use of root zone sensor (RZS) to obtain soil moisture status and to replenish the water in growing medium to a preset level. In principle, this method by-passes the need to calculate ETC and works for any crop, as long as the set-points for the irrigation controller are correctly chosen.
So far, applications of RZS for irrigation management have been less common than those of the water balance method, but novel types of RZS, which are based on the measurement of soil dielectric properties, have opened new possibilities for irrigation scheduling Anacetrapib and nowadays, after the doubts originated from the first attempts with gypsum blocks, the irrigation industry worldwide has recognized that RZS�� are valuable tools for modern smart water application technology in intensive agriculture.In this review, the main features of RZS�� (for both soil moisture and salinity) designed to be connected to irrigation controller for commercial cultivations are identified and discussed. The paper is based on classical and more recent literature on soil moisture sensing technology and its application to irrigation scheduling.The findings, also unpublished, of our recent experimental works conducted in the framework of national or international projects (see Acknowledgements) have been considered. These works concern mostly the outdoor cultivation of pot ornamentals, which is an important horticultural sector in Italy.The main area for this kind of cultivation is located in Tuscany, around the town of Pistoia, definitely the most important centre in Europe for landscaping ornamentals . In this area, nearly 1,400 ha, of approx.