State of the art in monitoring and modeling soil moisture at various scales for irrigation purposes.

Soil moisture is a key state variable for understanding processes evolving in the hydrologic cycle and, in particular, for developing good management practices of irrigation water. Re-cently, the techniques for monitoring water content in soil are receiving considerable attention and are undergoing substantial changes and improvements. In this paper, the major methods to measure soil water content are reviewed from the more classic to a few new ones, but with the central thread to frame them within model applications that exploit the measured datasets. The various traditional and more up-to-date methods are reviewed by the central thread of techniques developed to measure soil moisture interwoven with applications of modeling tools that exploit the observed datasets.