Soil organic matter & hydrogen peroxide demo

Are you studying soil science, gardening, or agriculture with your students? If so, you have probably learned that soil is a mixture of sediments and organic matter. But different soils have different amounts of these two ingredients. A soil’s organic matter content is important, especially when considering a soil’s ability to support plants.

In this demo, qualitatively compare the organic matter content of two soils. You can test the soil samples for organic matter by putting hydrogen peroxide on the soils and watching for a reaction (bubbling). More bubbles = more organic matter!

In this post, you will learn how to set up a soil organic matter demo in your classroom. You can also get print-formatted versions of these directions, worksheets, handouts, and classroom posters to use during this lab in my Soil Science Unit!

Soil Science Unit: with 5 lab activities! Soil horizons, textures, porosity, permeability, & more!

Gather Your Materials

Gather the following materials for the demo. You will need:

~2 Tbsp (15 mL) samples of 2 types of soil:
- Soil A: compost
- Soil B: a soil with less organic matter (look for a light-colored soil that has few plants growing in it).
3 small beakers
Laboratory personal protective equipment (gloves, safety goggles, lab coats)
6% hydrogen peroxide (available at pharmacies)
Eyedropper
Student lab handouts (1 set per student)

You will find worksheets, printable directions, and a materials list for this demo in my Soil Science Unit.

Safety Notes

Read and comply with all safety information and warnings on the hydrogen peroxide bottle. Before starting this demo, ensure all participants are prepared to safely handle hydrogen peroxide.
Ensure all participants and observers wear the appropriate personal protective equipment (gloves, lab coat, safety goggles).
Adult supervision is required at all times during this activity.

Directions

Do not tell students where soil samples A and B came from until after the lab. Explain that the two soil samples contain different amounts of organic matter. Hydrogen peroxide reacts with the organic matter in the soil, making bubbles or fizzing sounds.
Place ~2 Tbsp (15 mL) of soil A into a beaker
Place ~2 Tbsp (15 mL) of soil B into another beaker
Pass around the soils. Students should observe each soil and describe it.
Put on personal protective equipment.
Ask your students to gather around and watch as you squeeze an eyedropper full of hydrogen peroxide onto soil A and watch/listen for bubbles and fizzing.
Repeat the previous step with soil B. Which soil reacted more?
Finally, reveal that one of these samples came from a compost pile. Can students guess which one?

In this classroom demo, observe how soil organic matter reacts with hydrogen peroxide.

Reflection Questions

Describe soil A (color, texture, feel)
Describe soil B (color, texture feel)
What happened when your instructor added hydrogen peroxide to soil?
Did one soil react more than the other? Which soil reacted the most?
Hydrogen peroxide reacts with organic matter. What does this tell you about soils A and B?

This lab comes from my Soil Science Unit!

Your students will love the illustrated learning materials, plus you’ll support Wild Earth Lab with your curriculum purchase!