Measuring Soil Water Content: A Review

Soil water content (SWC) is a soil property that plays a crucial role in a large variety of biophysical processes, such as seed germination, plant growth, and plant nutrition. SWC affects water infiltration, redistribution, percolation, evaporation, and plant transpiration. Indeed, the quantification of SWC is necessary for a variety of important applications in horticultural systems, such as optimization of irrigation volumes, fertilization, and soil-water-budget computations. In recent decades, a substantial number of different experimental methods have been developed to determine the SWC, and a large body of knowledge is now available on theory and applications. In this review, the main techniques used to determine the SWC are discussed, first by describing the physical principles behind the most popular methods and then by addressing how the various spatial scales might affect the different methodologies when applied.