# Porosity and Permeability

By Mark Skiles

Objective:

This activity will help you understand that water moves through different types of soil at different rates. The movement of the water depends upon the soil's porosity and permeability.

Materials:

• ring stand
• funnel
• cotton balls
• large beaker
• (2) 100 ml graduated cylinders
• 4 different types of soil
• pencil

Procedure:

1. Set up apparatus so that ring stand is supporting funnel (a clamp or ring may be used to hold funnel in place). There should be ample room beneath the funnel for the large beaker to fit.
2. Place a cotton ball in the small end of the funnel.
3. Using a graduated cylinder, measure 100 ml of soil #1 and place it in the funnel, on top of the cotton ball.
4. Place the beaker underneath the funnel.
5. Using the other graduated cylinder, measure 50 ml of water and dump it into the funnel. Let the water percolate through the soil and collect in the beaker for 3 minutes only!
6. Measure the amount of water in the beaker and place this number in data table #1.
7. Clean apparatus, placing the used soil in the designated area. Then, repeat steps 2-6 for soil samples 2-4. Record all data in data table #1. Be sure to complete questions.

DATA TABLE #1

 water amount added to soil water amount in beaker (ml) percentage of water in soil sample #1 sample #2 sample #3 sample #4

Questions:

• Using your text, define porosity and permeability.
• In which of the soil samples did the water percolate the quickest? Why did this happen?
• In which of the soil samples did the water percolate the slowest? Why did this happen?
• Using the dissecting scope, observe the 4 soil types on low power. Sketch what the soil particles look like in the space provided. sample #1 sample #2 sample #3 sample #4