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Science Project on Soil Porosity

A science project can help students explore an aspect of what they are learning in class through hands-on experience. When dealing with geology, students may study the properties of soil. One of these properties is its porosity. To help students understand what soil porosity is and how to determine the porosity of a soil sample, you can help them with a simple project.

Soil Porosity
- Even though soil may appear to be solid at first glance, it usually contains pockets of air between the particles of soil that may be too small to see. When it rains or water is added to the soil, the water fills in these air pockets. The amount of water that the soil can hold helps you determine the porosity of the soil, or the size of the air pockets in the soil. Different types and densities of soil affect the porosity.
Materials
- To complete a science project on the porosity of soil, you will need to provide specific materials. You need two graduated cylinders that are the same size, soil and water. Provide your students with several different types of soil so they can test the porosity of each and compare the differences between the two. You can either give each student their own materials, split the class up in groups or complete the project together as a whole class.
Procedure
- Instruct the students to fill one graduated cylinder to a specific mark with the soil. Fill the other graduated cylinder to the same mark with water. Pour the water from its container into the container of soil until the water reaches the soil's surface. Record the amount of water left in its original graduated cylinder. Divide the amount of water left in the cylinder by the amount poured into the soil. Determine the amount poured into the soil by subtracting the amount left by the total amount in the cylinder at the beginning of the experiment.
Variations
- Different types of soil are composed of varying sizes of particles. The sizes of the particles in the soil affect the porosity of that type of soil. Students can compare the porosity of various types of soil by repeating the experiment with each type of soil. Another variation is to complete the process with the same type of soil, but alter the density of that soil. For instance, if you press the soil down with your hand, evaluate the effect on its porosity. You can also use other objects to press the soil down, such as a hammer or small mallet, to determine the effect on porosity.

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