A theory describing both vapor and liquid phases of moisture transfers in porous materials is developed. The two equations included extend previous work, which only considered moisture and temperature gradients, by also including solute concentration effects. The new equations include six diffusivities to be considered in describing vapor and liquid movement in soil. Three liquid diffusivities are for liquid‐phase flow associated with water content, temperature, and solute concentration, and three vapor diffusivities are for vaporphase flow. Steady‐state heat and mass transfer laboratory experiments were performed by using moist salinized and solute‐free closed soil columns. From observations of water content, temperature, and solute distributions, five of the diffusivities (vapor diffusivities due to temperature, water, and solute concentration and liquid diffusivities due to temperature and solute concentration) are determined. The isothermal liquid diffusivity as a function of soil water content is determined in a separate experiment. In general, the liquid diffusivities are larger than the vapor diffusivities for the experimental conditions considered. For the soil conditions investigated, the water fluxes due to the solute gradients are nearly equal to the water fluxes due to the temperature gradients within salinized soil columns, but the water fluxes resulting from gradients in soil water content are small in comparison. To test the validity of the theory, two different approaches are used. The first approach involves using water diffusivities of moist solute‐free soil along with the new theory to predict steady‐state water distributions within moist salinized soil for comparison with observations. The predicted values of soil water content are in good agreement with the observed values. The second approach is to predict steady‐state soil water distributions within the moist salinized soil column while neglecting the solute effects on soil water movement. The predictions using this approach are markedly different from the experimental observations.

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Water evaporation and solute transport were studied in open soil columns. The study included two different soil materials — Clarinda clay (fine, montmorillonitic, mesic, sloping Typic Argiaquoll) and Fayette silty clay loam (fine‐silty, mixed, mesic Typic Hapludalf) — and three conditions. Two conditions were noncompacted solute‐free and salinized noncompacted soil columns of both Clarinda and Fayette soils, and one condition was compacted salinized soil columns of Clarinda soil only. The initial soil water contents were 0.271 and 0.181 m3 m−3 for noncompacted Clarinda and Fayette soils, respectively. The initial soil water content of compacted Clarinda was 0.393 m3 m−3 The initial KCl concentrations were 1.11 and 0.92 mol kg−1 of soil solution for Clarinda and Fayette soils, respectively. Measured ratios of evaporation loss from the noncompacted salinized soil columns to the amount of water evaporated from noncompacted solute‐free soil columns increased with time from 0.78 to 0.89 for Clarinda and 0.90 to 0.95 for Fayette soils. Evaporation from noncompacted Clarinda soil increased with time from 0.73 to 0.77 of the evaporation from compacted Clarinda soil. A numerical model of heat, water, and solute transfer was used to predict distributions of temperature, water content, and solute concentration for a given evaporation rate. Efficiency of the model for reproducing the water content and solute concentration ranged from 94.5 to 61.1%. The predicted and observed solute concentrations increased with time in the upper 0.02 m of noncompacted soil. Also, the upper soil portion, the 0.05‐m layer, dried drastically. Both observations and predictions indicate complex interactions between heat, water, and chemicals near evaporating surfaces.