We have launched an online web calculator to process soil infiltration rate measurements collected using a Disc Permeameter. The calculator analyses measurements made at different tensions. It is a beta product, primarily made to assist us in assessing soil infiltration, porosity etc. We are keen for any feedback!
Disc permeameters (also called tension infiltrometers) are valuable tools for measuring how water moves through soil. Unlike ring infiltrometers that measure saturated flow, disc permeameters apply water at controlled negative pressure (tension), allowing you to assess the amount of flow through specific pore sizes. This gives you deeper insights into soil structure, compaction, and drainage capacity.
By measuring at multiple tensions, you can determine how much flow occurs through large structural pores versus the fine-textured soil matrix. This reveals critical information about soil structure and preferential flow pathways. Different pores sizes provide different benefits:
- Macropores: > 0.075-0.1 mm – drainage, aeration, rapid flow
- Mesopores: 0.03-0.075 mm – intermediate drainage and retention
- Micropores: < 0.03 mm – water retention, slow flow (requires tensions < -100 cm)
Disc permeameters measure flow through macropores and larger mesopores only. They cannot assess micropores, which require different methods such as pressure plate apparatus or water retention curves. The practical tension limit for disc permeameters is about -15 to -20 cm due to air entry through membranes and extremely slow infiltration rates at more negative tensions.
We have a comprehensive guide that explains the permeameters and processes in more detail and a Frequently asked question page to help out.
If you want to try understanding your soil this way, contact us. The equipment is not readily available and it does take effort to learn to use if correctly.