Salt and water movement in relatively dry soil

Abstract

When dry crystalline salt is placed in contact with relatively dry soil, water is found to accumulate in the soil immediately adjacent to the salt, and dissolved salt moves into this wetter region. A recent paper by Parlange presents a theory modelling the salt and water movement in such situations. To allow this theory to be checked against experiment, basic data on water potentials and water and salt diffusivities as functions of water content for the particular soil used are necessary. Such data, as well as data showing salt and water movement in soil near crystalline salt, are reported and used to check the Parlange theory. The theory is shown to have some limited success in predicting the salt movement into the soil, but to inadequately explain the water distribution in the wetter region adjacent to the crystalline salt. It is suggested that this failure is due to significant water movement in the vapour phase into the wetter soil, which is not accounted for in the theory.