Water Vapor Transfer in Dry Soil1
- R. J. Hanks2
Water vapor transfer in three dry soils was measured. The influence of porosity and depth of dry soil was investigated. Measurements were made primarily under isothermal conditions. Some measurements were made on one soil under nonisothermal conditions where the samples were radiated with a heat lamp. Liquid water movement was eliminated as a factor by treating the soil with a chemical water repellent.
Calculations of water vapor transfer based on simple diffusion were made. The ratio of measured to calculated values was 1.38 for the Ladysmith silty clay loam, 1.32 for the Geary silt loam, and 1.04 for the Sarpy fine sandy loam. Porosity and depth of dry soil had no measurable influence on the ratio of measured to calculated values. This suggests that diffusion is the primary process involved.
The ratio of the measured to calculated values for the Geary silt loam was 1.23 for the radiated samples. This is slightly less than the ratio measured for isothermal conditions which, considering the errors involved, indicates that simple diffusion theory is approximately correct for water vapor transfer in dry soil under both isothermal and nonisothermal conditions.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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