ABSTRACT
In order to establish a common understanding, we first need to clarify or explain our characterization of the term precision water management. The traditional meaning of precision water management has been that of either applying precise amounts of water to crops or applying water at precise locations (e.g., within the soil profile) or at precise times. Perhaps a good example of this traditional definition is drip irrigation, which is generally accepted as a very precise irrigation method because water can be precisely controlled with regard to application rate, timing, and location with respect to the plant. This definition continues to be used today in some areas. However, in this chapter we define precision water management as site-specific water management, specifically the application of water to a given site in a volume and at a time needed for optimum crop production, profitability, or other management objectives at that specific site. This is in contrast with a simultaneous application of a single amount to the entire area of the irrigation system. Moving irrigation systems have been used to accomplish this in all known applications thus far, and will be the primary focus in the bulk of this chapter.
