Have you ever walked through a garden, farm, or forest and noticed the soil beneath your feet? Soil may look like simple dirt, but it is actually a complex system filled with minerals, organic matter, water, air, and living organisms.

These components work together to support plant growth and food production. Scientists and farmers study soil ecosystems to understand how soil health affects crops and the environment.

Healthy soil plays an important role in regenerative agriculture, a farming approach that protects soil ecosystems while producing nutritious food.

Materials:

• Device with internet access
• Notebook or digital document for recording observations
• Optional: soil sample
• Optional: magnifying glass or hand lens

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.
• If 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.

Observing Soil:

Hand holding healthy soil

This photo shows a hand holding healthy soil full of microorganisms created by sustainable regenerative agriculture practices.

Observe a soil sample given to you by your teacher, and/or examine the image of soil.

Record your observations:

1. What color is the soil?
2. What textures or particles do you see?
3. Are there visible pieces of organic material, such as leaves or roots?

Teacher Note: Encourage students to think about soil as a mixture rather than a single material.

As You Read, Think About:

• What is soil made of?
• How do the parts of the soil work together?
• Why does soil matter for plant growth?

What is Soil?

Soil is more than just dirt; it is a complex system made up of both organic and inorganic materials that support plant growth. Organic matter is made of once-living things like plants, animals, and microorganisms. As these materials break down through decomposition, they form humus, a nutrient-rich substance that helps store important nutrients plants need to grow. Inorganic matter comes from nonliving sources such as rocks and minerals. Over time, weathering and erosion break rocks into smaller particles that become part of the soil, while water and air fill spaces between soil particles. Soil forms slowly through the interaction of several natural factors, including parent material, climate, living organisms, location, and time. Understanding how soil forms and what it contains helps scientists and farmers protect soil health and grow healthy crops.

Check Your Thinking:

• What are the two main types of materials in soil?
• Can you give an example of each type?

T-Chart Time:

Create a two-column chart that identifies the organic and inorganic components of soil.

Teacher Note: Students may list items such as leaves, roots, microorganisms, rocks, minerals, water, and air.

How Soil Forms:

Did you know that soil forms through different environmental factors? The factors that influence soil formation are:

• Parent material
• Climate
• Organisms
• Topography
• Time

Think About It:

Teachers may wish to select 2-3 questions based on available time and student readiness.

1. What is parent material, and why is it important in soil formation? Parent material is the original material from which soil forms. It can include bedrock, volcanic ash, river sediment, or material deposited by glaciers or wind. The parent material determines the minerals and texture present in the soil.
2. How does weathering help create soil from rock? Weathering breaks rocks into smaller pieces through physical, chemical, and biological processes. As rocks break apart, minerals are released and become part of the soil. Over time, these particles mix with organic matter to form soil.
3. Why does soil form more quickly in some climates than others? Climate influences temperature and rainfall. Warm, wet climates often speed up weathering and decomposition of organic material, which allows soil to form faster. Cold or dry climates usually slow these processes.
4. What role do plants and animals play in soil formation? Plants add organic matter when leaves, stems, and roots decompose. Plant roots also help break apart rocks. Animals and microorganisms break down organic materials and physically mix the soil, contributing nutrients and improving soil structure.
5. Why does soil formation take a long time? Soil formation involves slow processes such as rock weathering, accumulation of organic matter, and development of soil layers. These processes can take hundreds or thousands of years.

Reflection:

• What is one new thing you learned about soil?
• What surprised you the most?

Extension: Soil as a System

Here are some generalizations about systems.

• Systems have parts.
• Systems can change.
• Systems have inputs and outputs.
• Systems have interactions.
• Systems have boundaries.

Examples of systems in our world can include the human body, a playground, a store, etc.

Create a diagram that includes the following components about soil as a system. Use arrows to show the interactions and how nutrients move through the soil system.

• Organic matter
• Microorganisms
• Plant roots
• Water and nutrients
• Weather
• Human actions

Sentence Stems:

Use these sentence stems to support your diagram creation.

• “Soil is a system because…”
• “These parts interact by…”