Water Permeability of Saturated Soils as Related to Air Permeability at Different Moisture Tensions

Abstract

Abstract The relationship among soil moisture tension, air permeability, and water permeability at saturation was determined for several disturbed soil samples ranging in texture from coarse sand to clay loam. A typical graph of tension versus air permeability shows that a slight tension is necessary before the air permeability is different from zero. With increasing tension, air permeability increases sharply until it levels off near the value of water permeability. The air and water permeabilities are nearly the same for tensions > 100 cm of H 2 O, unless cracking occurs. Then air permeability greatly exceeds water permeability. Air permeability at field moisture percentages and water permeability of saturated soil were determined for soil cores of known soil moisture tension. As with disturbed samples, the two permeabilities were nearly the same at tensions of 100 cm of H 2 O.