Teaching sequence

Work through this resource material in the following sequence:

15 minutes

Tune In: What is soil?

20 minutes

Find Out: Soils and farming

20+ minutes

Take action: Improve the soil

5 minutes

Reflection

Tune In: What is soil?

Step 1

Ask students to complete a Think-Pair-Share routine in response to the following image, which is also on the attached visual explainer (also available on the Student Worksheet).

Once complete, engage students in a class discussion around their thoughts about this image.

Through your discussion, lead students to the idea that this farmer is checking his soil. Perhaps he is using technology to help, or maybe he is taking photos of the soil. Why would he do this?

Explain to students that soil is the most important resource a farmer has: soil is the key to many important parts of a farmer's working life.

Step 2

Share the following video with students:

Why soil is one of the most amazing things on Earth | BBC Ideas (https://www.youtube.com/watch?v=OiLITHMVcRw)

Once complete, invite students to share what they found interesting or important about this video. You can use the points below to guide the discussion around the issues that are relevant to this lesson:

Volume of soil organisms (start to 00:30) - In a single gram of soil, there could be up to 50,000 microorganisms. In one teaspoon of soil, there are more microorganisms than people on the planet. What are these organisms? Scientists have identified a mix of bacteria, nematodes, tardigrades, fungi, worms, spiders, ants, beetles and other insects. There are also the bigger organisms that live underground, like wombats and bilbies - these also help to aerate the soil and add nutrients to the soil.
Earthworms (1:13 to 1:41) - As we can see, earthworms create tunnels through the soil. This helps to aerate the soil (bring air into it) so it doesn't get compacted. In addition to allowing air into the soil, these passages also help water flow through the soil. Healthy soils retain moisture so that there is still water for the plants and other soil organisms when it's not raining. When soils are aerated and not compacted, plants can send their roots down further into the soil, accessing nutrients and forming a stronger root base, which helps to make them more resilient to changes above ground.
Looking after soils (2:16 - 2:45) - Soils provide us with 95% of the food that we eat! It's pretty important so we need to look after it. Farmers have a very important job here as they are the people who are growing the food that we eat in our soil. Also, about 1 billion people around the world work in agriculture and rely on it for their income (this doesn't include all the people who are growing their food in their gardens at home).
Soils and climate change (3:00 - 3:20) - Healthy soils are essential in terms of climate change. Carbon dioxide is the main gas contributing to climate change, and healthy soils with healthy plants can absorb carbon dioxide, but unhealthy soils don't absorb so much. In fact, unhealthy soils can release carbon dioxide back into the atmosphere. Keeping our soils healthy is vital to meeting the challenge of climate change.
Farming and soils (3:20 - 3:35) - The video explains that intensive farming is one of the human activities that is a problem regarding healthy soils. In intensive farming, large land areas are used to grow many crops quickly and repeatedly. It is a problem for soils because the soils don't get to regenerate or restore themselves between crops. Because of this, the health of the soils can decline, and farmers need to use chemical fertilisers to add nutrients to the soil. However, these can harm organisms and prevent the soil ecosystems from working effectively.

Find Out: Soils and farming

Step 1

Students will now research actions that farmers can take to help their soils.

Students could work in pairs or small groups, or students requiring extension could work independently. Students could research some or all of the methods below, depending on time, age and ability.

Explain to students that there are a variety of actions that farmers can take to improve soils in order to improve plant growth. However, in this lesson, they will be focusing on the following:

Adding compost to the soil
Growing native plants alongside food crops or animals
Adding mulch to the surface of the soil (keeping the soil covered)
Chemical fertilisers.*

*Students requiring extension could also research the use of chemical fertilisers.

For each method they research, students should answer the following questions (also available on the Student Worksheet):

Method for improving soil
Describe this method (what needs to happen). Summarise in one or two sentences.
How does this method help the soil?
Do you think this method would be a lot of work for the farmer?
Anything else that is interesting or important (e.g. how it relates to climate change or how it might not be suitable for some climates).

Some suggested resources to help students in their research could include:

Composting:

https://www.youtube.com/watch?v=lGynzcwXZk4
https://www.environment.sa.gov.au/goodliving/posts/2019/05/guide-to-composting
https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/166476/how-to-compost-on-farm.pdf

Growing native plants:

Mulch:

Chemical fertilisers:

Step 2

Give each student/group a large piece of butchers paper and ask them to summarise the results of their research on the paper (if students have focused on more than one method for soil improvement, they may need more than one piece of paper). They will present the information on the sheet to other students.

Students can use keywords, sentences, bullet points, doodles or sketches to explain elements of their research.

Step 3

Invite students to share the results of their research with other students. The aim here is that all students will have an opportunity to learn about all the different methods for soil improvement listed above, so if students have only focused on one method, they could team up with other groups who have focused on different methods to share their findings.

Take Action: Improve the soil

Step 1

Remind students that maintaining and improving soil health can have important beneficial impacts on climate change, biodiversity and farm productivity.

Students will now imagine they are working on a farm as soil improvement managers. As part of their jobs, they need to conduct a series of tests to find out which of the methods researched earlier are the best for improving soil health.

Test instructions:

Students will use a range of different soil additives (compost, mulch, fertilisers) on the same type of soil to see how these additives affect plant growth. Explain to students that one of the ways that we know that soils are healthy is by how quickly plants grow, so growing plants in different types of soil could be used as the measure of how healthy a soil is.

Students will need:

soil samples (enough for four pots per student/group). The soil can be collected from somewhere around the schoolyard or from someone's home. If possible, try to choose soil that you know is a bit degraded (look for bare patches of soil or soil that has been recently disturbed).
containers for mixing soil with additives
pots for planting the seeds in the soil - you can use plastic or compostable plant pots
labels for identifying different additives in the soil samples
compost (from a compost heap or bought in a bag)
mulch (could just be sugar cane mulch)
fertiliser - make your own (e.g. https://sustainableholly.com/15-easy-organic-fertilizers-to-make-at-home/) or buy (e.g. https://www.bunnings.com.au/multicrop-1l-plant-starter-liquid-fertiliser_p3011214)

seeds (wheat seeds grow quickly and easily)
bottle or watering can for watering plants
warm sunny spot for seedlings to live.

Instructions

Students will be testing out three additives, so they will need one pot per additive. They should mix the additive into the soil in a separate container and then add the soil to the plant pot and label it. One plant pot should contain soil that has no additives.
Plant seeds into each container, water regularly, and leave in a sunny place.
Once seedlings start to emerge, you can begin analysing plant growth for length (you can measure them!) and health (are the leaves healthy looking, or are they curling up and going brown?).

Step 2

Using their test results, the soil improvement managers (students) will create an infographic (e.g. Canva) to communicate what their results showed about the different types of soil. Ask students to imagine that the infographic is going to their boss (the farmer), and they need to clearly explain what they did with the test and what actions they would advise the farmer to take to improve their soil.

Students can use this rubric to help them create their infographic.

Step 3

Finally, provide an opportunity for students to share their infographics with the class and engage students in a class discussion around the following:

Did everyone make the same recommendations to the farmer about the soil additives?
Why or why not?
What was similar and what was different?
How effective do you think these tests were in communicating soil health?
What could be improved next time?

Reflection

Invite students to read the following quote and respond to the questions below (also available on the Student Worksheet):

The nation that destroys its soil, destroys itself.
Franklin Delano Roosevelt, 32nd President of The United States of America

What do you think this quote means?
Do you agree with this quote? Why or why not?

The Role of Soil in Agriculture

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