Infiltration Rate vs. Gas Composition and Pressure in Soil Columns

Abstract

Infiltration is influenced by soil gases. Studies have found that CO 2 has a large impact on infiltration. Since CO 2 is highly soluble, soil flooded with it before infiltration has greater saturation and a greater infiltration rate. Our objective was to compare infiltration rates when soil pore gas consisted of (i) CO 2 at atmospheric pressure, (ii) air at atmospheric pressure, and (iii) air at various vacuum levels. A vacuum should, similar to CO 2 , reduce encapsulated gas and increase the infiltration rate. Results were that infiltration under 1‐ to 2‐mm constant‐head conditions tended to be more rapid at low air pressures. Falling‐head infiltration, from 67.8‐ to 13.8‐cm water head, was fastest with CO 2 , intermediate with a vacuum that removed all dry air gases, and slowest with air at atmospheric pressure. The final falling‐head infiltration rates with CO 2 and vacuum were 1.9 and 1.6 times faster, respectively, than with atmospheric air.