Soil is a habitat
A habitat is an area in which something lives. Soil is a habitat, and it is full of life!
The soil food web
The caterpillars of a native moth species burrow into soil. The vegetable caterpillar fungus uses the caterpillar for food. Its stem grows through the soil.
Around 25% of everything alive on the Earth uses soil as a habitat. Some animals live on top of the soil (in leaf litter or other organic matter), and others live below the surface. Some things live in the soil for their entire lives, and others live there for just a part of their lives. There are billions of microorganisms living in the soil too, but they are too small for us to see. Plants also live in soil. They depend on soil for air, water and nutrients.
Things living in the soil depend on each other and on non-living soil components like organic matter and minerals to survive. This interdependence and transfer of food energy is called a soil food web.
Soil means life – it keeps us alive and we need to protect soil to protect life.
Soil habitats differ from place to place
Soil habitats can be quite different. Soil characteristics affect what lives in it. For example, a soil that has lots of pore spaces for water and air usually supports more life than one consisting of hard clods. Temperature and rainfall also influence the types of plants and animals that live in the soil.
Soil habitats are everywhere
Soil habitats are everywhere, even in cold dry places like Antarctica. Bacteria live in the soil.
New Zealand native soil habitats
New Zealand native forests tend to be humid places that do not have big changes in temperature. Our forests may not have as many different animals as other rainforests around the world, but there is a lot of life under the ground. Believe it or not, the weight of earthworms under our native forests is greater than all of the other animals living in the forest!
Earthworms aren’t the only creatures on the forest floor – the leaf litter may hold hundreds of species of invertebrates like slaters and stick insects. Earthworms, invertebrates and microscopic organisms use the fallen leaves and other decaying matter as food. They break it down and recycle the nutrients so they can be used again and again.
Other native areas like tussock grasslands, alpine shrublands and coastal areas will have their own soil ecosystems. Anywhere there is soil, there will be a soil habitat.
Soil habitats in the city
The lawns and gardens around our houses and schools are home to all kinds of soil life, but we have to look to see it. Most soil organisms don’t like to be exposed to sunlight. We even create soil habitats by building compost systems. A spadeful of soil and food scraps or grass clippings added to an empty bin soon becomes home to insects, earthworms and microscopic creatures.
Not all the same
To the untrained eye, one earthworm often resembles another. Once you take a careful look, you’ll notice that, although earthworms have much in common, there are many differences too.
Jargon alert
Soil dwelling earthworms fall into three main niche groupings:
Epigeic earthworms live in compost and near the soil surface.
Endogeic earthworms live in the topsoil (top 20 cm).
Anecic earthworms live in the subsoil (as deep as 3 m).
It’s just as well that soil organisms break down and recycle plant and animal wastes. Consider just one type of waste – insect exoskeletons. If these were never recycled, we’d be knee deep in insect body parts. Imagine all of the fallen leaves, potato peelings and cow dung that would still exist. Life above the ground wouldn’t exist without the help of life below the ground!
Nature of Science
Scientists’ views and children’s views often differ. Scientists recognise that soil is full of life and responsible for energy transfer among millions of living organisms. Children often see soil as a dead, inert material.
Activity ideas
What makes up soil? uses an interactive or paper-based graphic organizer to explore student thinking about soil. This is a good pre/post student activity. Use it in combination with the teacher resource Alternative conceptions about soil.
New Zealand soil creatures combines reading, viewing, writing and presenting with New Zealand’s unusual mummified caterpillar and bioluminescent earthworms.
In Observing soil microbes grow vibrantly coloured soil microbes and watch as these microbes soft boil an egg in a compost bin.
Useful links
Learn more about New Zealand’s soil fauna with this guide to New Zealand soil invertebrates.
This article details some of the simple methods students can use to collect and sample soil creatures. Use the New Zealand soil invertebrate guide (above) to find the equivalent soil-dwelling species.
Soil Life uses storytelling, infographics and videos to explain soil basics to middle primary and high school students.
