ABSTRACT
Hygroscopic water content has been defined as the moisture that an initially dry soil will adsorb when brought into equilibrium with an atmosphere of 50% relative humidity (RH) at 20C.[1] It has also been defined as the moisture that adheres to soil particles and does not evaporate at ordinary temperatures.[2]
Hillel[3] describes soil hygroscopicity as the phenomenon where air-dry soil will generally contain several percent more water than oven-dry soil.
