Soil is not just dirt underneath your feet! Did you know that you are actually walking on living matter?! Dirt is dead. Dirt is made of inorganic materials like sand, silt, and clay. Soil, which is partially dirt of inorganic matter, is alive! Almost half of soil is dirt (inorganic matter); the other half is water and air. Only a small fraction is made up off living organisms. Yet these living organisms play a large part in our lifecycle and the life of soil. Roots from plants push into the soil creating passageways for water, air and nutrients. Ants, earthworms, rodents, snakes and insects build subterranean passages too. Go outside and scoop up some soil. You are actually scooping up living microscopic bacteria! A teaspoon of soil is full of more kinds of bacteria and bugs and organisms than there are people living on earth! In fact, although we know about 6,000 species of bacteria, there are millions we haven’t yet discovered! Bacteria in soil is key to our health. Organisms like worms and bugs and bacteria work to breakdown material into nutrients that are the life-giving structure of soil. Soil is a mixture of organic and mineral materials. Soil is also old. It takes hundreds and thousands of years to create an inch of topsoil! Soil is a critical part of the life cycle. Healthy soil. Healthy insects, plants, birds, food…and people! We need soil!
We need soil!
Activity 1 Types of Soil
Different climates, different organisms, and different topographic conditions create different types of soil. Soils are created depending upon geology, climate, topography, biology, and time. Deserts and rocky mountain areas have little soil. Warm, wet climates speed up the process of changing the earth surface into soil. Cool, dry climates work more slowly. Steep topographic areas like mountains have less soil than flat areas. Wind and water wash away or ‘erode’ topsoil while valleys act as collectors of soil. Get a few cups or containers and a large spoon. Save an egg carton to sort any large items, have jars with rubber banded perforated covers for worms and insects. If possible, grab a magnifying glass. Go outside. Walk to different parts of your yard, a park, a forest, a lakefront or river edge. Collect five different soil sources. Bring them in and begin to inspect them. Sort similar items from others. Put bugs together. Put worms together. Put rocks and stones and twigs together. Inspect the granules and other things you find. You will see that soil is different in different places. Take pictures of your different soil collections. Soils from forest, rangeland, agricultural, wetland and constructed ecosystems are all quite different. Begin to collect soil samples wherever you go!
Activity 2 Soil Systems
Soil is made of organic and inorganic material, air and water. It is a living working system. Collect cotton balls, gravel, garden soil, and grass seed. Collect 4 clear plastic liter bottles. Cut the top1/3 off of one of the plastic liter bottles; remove the cap and turn the top upside down in the bottom. Place cotton balls in the bottom. These represent the spongy subsoil deep below the surface. Next place a layer of gravel as the stony layer. Cover the stony layer with a thin layer of moistened garden soil. Sprinkle grass seed and cover seed with ¼” soil. Place your soil system in a sunny windowsill. Keep the soil moist. Take a picture of your soil system each day until the grass is over 1 inch tall. You have replicated the layers of a soil system!
Activity 3 Soil Filters
Soil absorbs and filters pollutants. When soil gets overloaded with pollutants and loses its ability to filter them, it becomes unhealthy. When rainwater runs from rooftops into roads and into rivers and lakes without being filtered by soils, it creates polluted water. In this activity, create 4 more replicated soil systems. Watch soil filter or attempt to filter pollutants. Make a list of pollutants you have around your home and school. Think about motor oil, laundry detergent, paint, insecticides, etc. Collect the following materials:
blue laundry detergent (1 ounce)
powdered cleanser (4 tablespoons)
cooking oil (1 ounce)
water - 4 cups (8 fluid ounces each)
muddy water (6 ounces)
Using a soil system for each treatment, prepare and pour the following solutions into your systems; label the ingredients for each system:
System 1: blue detergent + 6 ounces of water
System 2: powdered cleanser + 6 ounces of water
System 3: 6 ounces of plain water (best possible practice)
System 3: 6 ounces of muddy water
Imagine and record what will happen in each setup. Observe the water that runs through and drips into the bottom of the bottles. Reflect on what is different in each of the soil systems and why. What did you discover?
Activity 4 Soil Testing
Plants need soil that has Nitrogen (N), Phosphorus (P), and Potash (K) to grow. Phosphorus is essential for healthy roots, Nitrogen creates green leaves and Potash is essential for fruit and flower development. Plants require the correct pH level, or amount of hydrogen, to access the Nitrogen, Phosphorus and Potash. Different plants require different pH levels so we test our soils to understand the pH level. If the pH level is too low (or acidic) we can enhance the soil with more nutrients. pH is measured on a scale of 1 to 14 with a measurement of 7.0 being neutral. A number below 7 is acidic (sour) and above 7 is alkaline (sweet). Most plants thrive between 6.2 and 7.2pH. If the soil is too acidic, you may mix in some lime; if it is too base or alkaline, you can add some sulfur. To test the soil, you will need a Soil Testing Kit. Soil testing kits are available on line and at your nearest hardware store. The simplest test has four glass tubes or vials with different colored lids and different colored tablets. While the best time to test your soil is in the spring before planting, or after the fall harvest, it is important to test dry soil rather than wet.
Soil is essential to our health and well being.
Which climatic regions produce the most soil?
Soil is full of:
Inorganic matter in soil includes:
- A Grain of Sand Video by Dr. Gary Greenberg
- Underground Adventure
- The DIRT Connecting Natural and Built Environments
- Geology for Kids
- Soil Types
- Know Your Soil Type
- Soiled Again!
- Soil Types and Testing
- USDA Web Soil Survey
- Soil NET UK
- Twelve Orders of Soil Taxonomy
- Reverse Grafitti: Art by Cleaning
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