ABSTRACT
Soil’s moisture content by itself, regardless of its method of expression in any of the 14 different ways, is not sufficient to describe the status of water in soil. There are several hydrological processes that cannot be fully explained on the basis of soil’s moisture content alone. These processes include: (i) water absorption by plant roots, which differs among soils with different textures that have similar moisture content, (ii) water movement that may occur from one soil to another although their moisture contents are similar, and (iii) different soil moisture contents may occur in soils with similar management or environmental conditions. In addition to the moisture content, another property that is essential to a complete description of the soil water regime is the energy status of water in the soil. Soil’s moisture content is similar to the heat content of a body. It is the index of a system’s capacity in contrast to temperature, which is a measure of its intensity. Similarly, soil’s moisture content is a measure of the capacity factor while the energy status of the water is an index of its intensity.
