Essential Question:

How do we determine if the soil is healthy enough to support crops?

Have you ever tried to grow something that didn’t survive, like a houseplant indoors or a bush outside? Why do you think some plants grow better than others? In this activity, you’ll think like a soil scientist to figure out what makes soil healthy enough to support plant life.

 Figure 1: A farmer tests the soil

Materials:

• Device with internet access
• Notebook or digital document for recording observations

Safety Notes:

• When using technology, engage in safe, legal, and ethical behavior; this applies to devices (hardware), applications or programs (software), and interactions with others.
• When engaging with a soil sample, make sure to wash hands after touching the soil, and wash surfaces or containers that have been in contact with the soil. Do not eat or otherwise mishandle the soil.

How Do We Know If Soil Is Healthy?

Soil is made up of different materials. Let’s look at the diagram below to review the different parts of soil.

The right soil can help our crops grow strong and healthy. Unfortunately, some soil can make it very difficult for a plant to survive, let alone thrive. Soil scientists study soil to determine how well it supports life.

Healthy soil has a balance of air, water, and materials that plants need. Loose, slightly moist soil with organic matter, such as decomposing leaves, is healthy soil. If you find small organisms living in the soil, that can be an indication that the soil is healthy.

What Should You Look For in Healthy Soil?

• Dark color
• Crumbly or loose texture
• A little moisture, but not too dry or too wet
• Organic material (roots, decomposing leaves)
• Living organisms (worms, beetles)

Let’s Observe: You will be given three examples of soil. With your group, look at each sample closely. Using your sense of sight and touch, notice the color, texture, and moisture level. Record your observations in your notebook (digital or paper). 

Let’s Test:

After you’ve recorded your observations, it’s time to test each sample.

• Using the water dropper, add a small amount of water to each sample.
• Observe aeration:
• Gently press the soil.
• Record your observations.

Venn Diagram:

Create a Venn diagram to compare and contrast two of the soil samples. Be sure to include similarities (center of the Venn diagram) and differences (outer areas of the Venn diagram). Use evidence from your observations to support your thinking. Be sure to include which soil appears healthier and why.

 Figure 2: Venn diagram

Sentence Stems:

Use these sentence stems to support your notes in your Venn diagram.

• “This soil is healthier because…”
• “I observed that… which shows…”
• “The water behavior tells me…”

Color, Symbol, Image (CSI):

Figure 3: CSI for the Concept of School

Thinking About Soil

Thinking About Soil

Using the Project Zero CSI thinking routine, choose a color, create a symbol, and create or choose an image that represents soil. To support students who may need a reduced cognitive load, consider asking students to choose one or more areas of CSI.

Color

Think about what you’ve learned about soil and what it can represent to you. Explain your thinking: Why did you choose this color, and what does it represent?

Symbol

Design a symbol that represents what soil is. Think about the parts of soil and how it is a connection among living and nonliving things. Explain your thinking: What does this symbol represent? How does it show what soil is and does, and why that matters?

Image

Draw or choose an image that shows your idea of soil. What is taking place in the image? How does it show soil as a system?

Dive Deeper

How might your Color, Symbol, Image change depending on a different type of soil? If the soil was unhealthy or damaged, how might your CSI change?

Reflect on the Soil Investigation

Which soil sample seemed the healthiest? Why? What clues or observations helped you decide? How did observing the water interact with the soil help your decision?

Knowledge Check / Exit Ticket

What are three signs of healthy soil? Healthy soil is typically dark in color, crumbly or loose in texture, and will contain both organic matter and living organisms. Students' responses might contain ideas such as moist, roots, insects or worms, and a mix of particle sizes.

Why is soil structure important? It helps support root growth, helps plants get oxygen, and holds nutrients.

How does seeing how water interacts with soil help us to understand soil health? Water helps us to understand how aerated the soil is, which gives us clues to pore space and soil quality.

Reflection

What helped you to understand soil health? What was challenging? What would you do differently next time?

Extension

Choose one activity.

Choice One: Analyzing the Unhealthy Soil Sample

What was wrong with the unhealthy soil sample? What was it missing? What would you add or change to help the soil improve? Create a list or sketch of your plan to improve your soil sample. Possible Solutions: Students might improve drainage, add plants or organisms such as worms, or add compost.

Choice Two: Soil Recommendation

You are helping a gardener decide which soil to use. What would you recommend and why?