SEED Community

What is the relationship between soil porosity and soil permeability?

Printer-friendly versionPrinter-friendly version
Title:
What is the relationship between soil porosity and soil permeability?
Topic:
Porosity
Question: 

What is the relationship between soil porosity and soil permeability?

Answer: 

Let's take a closer look at the difference between porosity and permeability.

Soil porosity

The porosity of a soil refers to the volume of all the open spaces (pores) between the solid grains of soil. For growing things in soil, the porosity is important as it defines the volume of water that can be held in a given volume of the soil.

Soil permeability

Soil permeability is the property of the soil pore system that allows fluid to flow. It is generally the pore sizes and their connectivity—how well those pore spaces allow water to flow through the soil—that determines whether a soil has high or low permeability. Water will flow easily through soil with large pores with good connectivity between them. Small pores with the same degree of connectivity would have lower permeability, because water would flow through the soil more slowly. It is possible to have zero permeability (no flow) in a high porosity soil if the pores not connected. Near zero permeability also occurs if the pores are very small, such as in clay.

On the PlanetSEED Web site, the Porosity experiment and the Permeability of Soil activity can help you understand more about these concepts.


Looking for more information?