INSITU MEASUREMENTS OF MOISTURE AND SALT MOVEMENT IN FREEZING SOILS

The paper presents the results of field studies on the movement of moisture and salts during freezing of Prairie soils. It is shown that large fluxes of water can migrate to the freezing front and move upward into the frozen soil above. The fluxes are largest in light-textured soils having a water table at shallow depth. However, substantial amounts of soil moisture may also move in silty clay, silty clay loam, and clay soils under dryland farming provided there is sufficient water present to support capillary flow. The dynamics of soil moisture transfer under natural conditions as a result of freezing involves movement of water in both vapor and liquid phases. A close association is observed between changes in the ice content and electrical conductivity of a silt loam after freezing. Data showing the redistribution of water and salts during thawing are also presented and discussed.