Forum/Soil diary task (optional)

In the previous sections, you learned about soil components (minerals, organic matter, water, and air) and how their arrangement forms soil structure – aggregates and pore spaces that create a living habitat below ground. Now it is your turn to visualise this hidden system.

Draw your own soil profile that shows not only soil horizons but also soil structure. Once you have finished, you can share it in the forum or document it in your soil diary. You may draw by hand or digitally.

Go to the Forum

Your drawing can be simple or detailed – the goal is to think scientifically, not artistically. Include:

• At least two or three soil horizons (e.g., topsoil, subsoil, parent material)

• Soil aggregates (small clusters of particles)

• Different pore sizes (large and small pores)

• Roots growing through the soil

• Water in some pores and air in others

• At least a few soil organisms (e.g., earthworms, fungi, microorganisms)

If you want, you can follow these guiding questions:

1. Where are most organisms located in your profile? Why?

2. Where do you place larger pores? Where do you place smaller pores?

3. In which direction does water generally move through soil?

4. Where is oxygen most available?

5. What would happen in your drawing if the soil were compacted?

6. How might land management (e.g. vegetation cover, heavy machinery, organic inputs) change your soil structure?

Try to connect your drawing to concepts from the lesson:

• 45 % minerals, 5 % organic matter, 25 % water, 25 % air (in a healthy soil)

• The “city” analogy of buildings (aggregates) and streets (pores)

• The idea that soil structure determines whether life thrives or struggles

Bonus: For inspiration, have a look at this Figure from an article by Erktan et al. and reflect on how soil structure influences life in soil.

Tip: Learn more about the soil food web and soil organisms in Module 2, Topic 3.

© Effects of soil physical structure on trophic interactions and consequences for soil biodiversity, Erktan et al. (2020), CC BY-NC-ND 4.0, no changes were made to the original figure.