The * soil porosity*, also called the

*, is the ratio of the volume of voids (open spaces, i.e. air and water) in a soil to the total volume.*

**void fraction**$latex n = \frac{V_v}{V_t}\newline\newline

=\frac{V_g + V_w}{V_g + V_w + V_s}&s=2$

*Where:*

*V _{v} = Volume of voids (m^{3} or ft^{3})*

*V*

_{t}= Total Volume (m^{3}or ft^{3})*V*

_{g}= Volume of air (m^{3}or ft^{3})*V*

_{w}= Volume of water (m^{3}or ft^{3})*V*

_{s}= Volume of solids (m^{3}or ft^{3})Porosity is thus a ratio between 0 and 1, which can also be expressed as a fraction.

It is the fraction of the material that is not solid. The soil porosity is closely related to the void ratio, which is defined as the ratio of voids to * solids*, rather than

*, volume.*

**total**
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