02557nam a2200241 a 450000100080000000500110000800800410001910000160006024500480007626000420012430000090016650000180017552020220019365000140221565000130222965000090224265000100225165000100226165000080227165000150227965000090229465300120230315593181999-11-04       1986    bl uuuu  m   00u1 u    #d1 aLIMA, L. A.  aSalinity effects on soil-water diffusivity.  aDavis: University of Californiac1986  a96p.  aM.Sc. Thesis.  aSalt effects on water movement in usaturated Yolo loam soil are explored by comparing soil-water diffusivity values determined by Bruce and Klute´s method in soil columns treated with SAR values 0,5 and 15 and wetted with water containing 15, 5, 2 and 0 me/l. Sorptivity values for these conditions are also compared. Total soil solution concentration estimated by electrical conductivity measurements and NA and CA concentrations measured by flame photometry are discused. Salt effects on soil-water diffusivity were more pronounced at larger values of water content. Movement of water in Ca-saturated samples was significantly affected only when the soil solution concentration was smaller than approximately 2 me/l. Soil samples treated with SAR 5 presented reductions in soil-water diffusivity when the solution concentration was equal to or smaller than approximately 3,5 me/l and the water content larger than 0,35 cm3/cm3. The soil-water diffusivity was also affected when the solution concentration was equal to or smaller than approximately 2 me/l and the water content larger then 0,30 cm3/cm3. Soil-water diffusivity of samples treated with SAR 15 was affected basically at all values of water content when the soil solution concentration was equal to or smaller than approximately 3,5 me/l. When such concentration was a large as 5 me/l, reductions in soil-water diffusivity were apparent only for water contents larger than 0,25 cm3/cm3. Chemical analyses of soil solution after infiltration revelated that most soluble salts in the soil column were carried near the wetting front. Significant displacement of Na by Ca occurred in soils treated with SAR 5 and 15. Although Bruce and Klute´s method does not apply for chemically unstable and swelling soils, the slope of the plot of distance to the wetting front versus square root of time fitted the Boltzman variable for the water content of wetting front satisfactorily. This fact suggests good reliabillity of reported soil-water diffusivity values.  adiffusion  asalinity  asoil  awater  aÁgua  aSal  aSalinidade  aSolo  aDifusao