Salinity is a factor in most of the western soils. Evaporation of water in the soils leaves the salt concentrated in the remaining solution, building up large concentration gradients even in soils containing relatively low concentrations of total soluble salts. These salt gradients can affect water movement both by acting osmotically and by changing the soil structure and water absorption capabilities. The mechanisms of osmosis were delineated, hydrodynamic dispersion coefficients were determined, and effects of these salt gradients on evaporation were determined. NaCl decreased evaporative CaCl2 tended to increase evaporation. Thin dense crusts of the type formed by raindrop action tended to reduce evaporation when overlying looser soil with larger pores. The mechanisms of osmosis are so involved with ion type, mineral type, structure, and texture that much more work is needed to sort out all the interactions and develop predictive criteria. (Author)