Hysteresis in Soil, Its Causes and Influences

Abstract

Soil hysteresis is a natural phenomenon that occurs in soil water retention curve (SWRC) and soil water characteristic curve (SWCC), the mismatch of the drying (drainage or desorption) and wetting (sorption or adsorption) curves in each curve is called hysteresis in soil, i.e., At any potential (ψ), there is a discrepancy between the soil water content (Θ or Å ) in the curve of desorption and adsorption, this indicates that the amounts of water collected during the desorption cycle are not the same as the amount of water for adsorption the soil at the same applied pressure (suction ψ). So, this relationship between soil water content (Θ or Å ) versus soil water potential (ψ) is non-unique. The difference is caused by a number of mechanisms, including: Contact Angle (θ), Adsorption, Bubble-form, Matric potential, Ink-Bottle Effect, Entrapped Air, Wetting and Drying History and Pore Size... etc. The explanations concern both (water and soil). Soil hysteresis has a degree, that varies depending on the type of clay minerals and pore size... etc. In this review paper, what are the causes of soil hysteresis, the hysteresis degree, and what does it influence? will be discussed.