ABSTRACT
The soil stores the water used by plants to sustain life. The amount of soil water that can be used by the plant varies, due to characteristics of the soil (e.g., texture) and of the plant (e.g., root distribution and depth). Knowledge of the amount of water available to the plant, or plant available water (PAW), is needed to determine the agricultural or ecological potential of soils and is used in many agronomic applications, such as irrigation scheduling programs or crop production models. It helps define the water content limits beyond which plant growth is affected because of insufficient or excessive amounts of water, or beyond which water is lost out of the root zone due to deep percolation. The water content is typically expressed on a weight (gm3) or volume (m3m3) basis.
