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The Value of Soil                                                           



CONTENT OBJECTIVE: Understand that good soil is limited in nature and needs to be protected.
LIFE SKILL OBJECTIVES: Respect and responsibility for the land and critical thinking.
INDICATOR: List ways that the soil can be protected in their community.
SUBJECTS: Science, social studies, math



MATERIALS
  • Large apple (one that is easy to cut)
  • Knife
  • Cutting board

INTRODUCTION

What do the following phrases mean to you?
Soil is the foundation for life on Earth.
Dirt made my lunch.
Soil is the number one natural resource in Iowa.

What do most plants grow in?
Most plants depend on soil as their foundation and source of nutrients. Some plants grow in water or other non-soil foundations.

What do most animals eat and how does that relate to the soil?
Wild and domestic animals and people depend on the soil to grow plants for food. Even if animals consume other animals, usually at the beginning of the food chain, an animal has eaten plants. So, we can say that dirt, or soil, made most of the foods we eat.

Plants need four natural resources including sun, soil, water, and air to grow.
Why is soil the number one natural resource in Iowa?
More than 90 percent of the land in Iowa is in some sort of agriculture production because of the rich soil. The rich soil that produces abundant crops and feeds millions of livestock animals makes Iowa one of the top three agriculture producing and exporting states in the United States. As little as 150 years ago, settlers fled to Iowa because the rich soil could grow ample food for their families and the animals they raised.

How valuable is soil to all the plants and animals on planet Earth?
Let's find out.

DO
We are going to use an apple to represent planet Earth. We're going to cut the apple into pieces until we find out how much soil is left to grow all the food to feed more than six billion people and all the animals that are in our care.

*Apple Earth
  • I am going to cut the apple into fourths. What does that mean? Cut it into four equal parts. Cut the apple into four lengthwise sections and take away three parts. These three parts represent the portion of the earth covered by water. Where do we find water on planet Earth? Oceans, river, lakes, ponds, streams, etc. In math, what do we call the one piece that is remaining? One quarter or one fourth (1/4). The piece that is left, or one quarter of the Earth, represents land.

  • I am cutting this quarter in half lengthwise. How many pieces will I have? Two. Cut the apple. I'm removing one of those halves (1/2) because it represents areas of the Earth where plants we eat can't grow because it is too cold, or too wet.

What places are too hot?
Deserts, equator

What places are too cold?
The poles, places where there is frozen ground

What places, besides bodies of water, are too wet?
Swamps

We cut one fourth of the apple into half, how much of the planet earth do we have left that might grow plants for the food we need?
One eighth or 1/8.

  • Now I am cutting the remaining eighth of the apple, representing the Earth, into fourths or quarters. How many pieces will I have? Four Cut the apple. I am removing three fourths or quarters because they represent areas of Earth where plants can't grow roots into the ground. These surfaces may be called impervious which means incapable of penetrating or being passed through.

What kinds of things cover the soil on the ground to make the ground impenetrable?
Roads, houses, industries, shopping malls, schools, parking lots, mountains, and forests can cover the soil on the ground.

How much of the apple or planet Earth is left to grow crops for the more than six billion people and all the billions of animals in their care?
We have one fourth of one eighth, which equals one thirty-second or 1/32 of the planet earth that is left to grow the food to feed all the people and the animals in their care.  But, do we grow plants clear into the core of the earth? No  What do you call the layer of soil where plants grow? Topsoil

Peel the skin off the remaining section. The skin of this little piece represents topsoil, the part of the soil that plants grow in.
This is the amount of soil left on our planet Earth to grow all the food to feed all the people and the animals in their care.

Can we divide this little piece, the skin of 1/32 of an apple that represents the topsoil on the Earth - into over 6 billion pieces?
(*Apple Earth was adapted from Heimlich, Joseph, James Hollyer and Bill Owen. "Apple Earth." Cycling Back to Nature, Soils Alive! Washington, D.C.: National 4-H Council. 4H-326)

REFLECT

Is there very much topsoil left on planet Earth to grow all our food?
No

Do you think Iowa shares a large portion of that valuable topsoil?
Yes, the rich topsoil in Iowa makes it a major state to grow food to feed billions of people and animals here and around the world.

What does that mean we should do about this valuable resource?
Be responsible, take care of the soil, keep it healthy so that it can grow food for many more generations.

What do people do on Iowa's rich soil?
(Make a list on the board.) People grow or manage and harvest these things that depend on the land.

  1. Grain crops such as corn, soybeans, alfalfa hay, and oats. In fact, Iowa ranks number one or two in corn and soybean production.
  2. Livestock such as pigs, egg-laying hens, beef cattle, dairy cows, sheep, and turkey. Iowa is a top livestock producing state. The animals eat the grain grown in Iowa and their manure is worked back in the soil as a nutrient to feed the plants.
  3. Orchards, Christmas trees, nursery stock, berries, pumpkins, vegetables, flowers, and herbs.
  4. Pastures, prairies, roadsides, waterways, lawns, golf coarses, and other places where grasses grow.
  5. Forests and other places where trees are grown for profit
  6. Horses, dogs, cats, goats, geese, buffalo, elk, ostrich, emu and other domestic animals eat food that started with the land.
  7. Wild animals such as deer, raccoons, squirrels, rabbits, skunks, pheasants, wild turkeys, Canada geese, and mice, depend on food grown from the soil, much of which comes from agriculture production.
  8. Rocks and minerals such as limestone and sand and gravel.

People put these things above or below the soil.
  1. Roads, parking lots, sidewalks, (impervious surfaces.)
  2. Drainage tiles, water pipes, utility lines under the soil.
  3. Garbage.
  4. Houses, business offices, factories, schools, shopping malls, hospitals, government offices, and other buildings.
  5. Household, industrial, and agricultural chemicals; organic matter; and solid waste.
  6. Recreational places such as amusement parks, race tracks, and athletic and cultural centers.

Does our list indicate that we sometimes don't use our soil very wisely?
Give examples.

APPLY

What are some examples of how people, including you, can protect and conserve the soil?
Plant grass, trees, shrubs, flowers, vegetables, grains as cover crops to prevent the wind from blowing away soil and to put roots in the ground to prevent water from washing away soil. Don't pollute the ground with garbage or too many chemicals or fertilizers. Add nutrients back to the soil by using crop rotation, adding commercial fertilizers or organic nutrients such as animal waste, or by composting. Build on locations that is not good crop land.

What evidence is there that the soil is considered valuable near where you live?
The price of land is very expensive. (You may want to look in newspapers for the price of lots in your community or the value of farmland in your county.) People may grow lots of crops, gardens, flowers, grass, trees, and shrubs. You may smell manure that has been spread on the fields nearby. You see corn growing in a field one year and soybeans the next (an example of crop rotation where soybeans put nutrients back in the field.) You see different methods of planting crops around hills and using grass or planting strips in the fields. You have garden clubs and a large Master Gardening group in town. There are articles in the local newspapers and programs on the radio about the soil and growing plants. Your community depends on agricultural crops such as herbs, tree fruits, vegetables, as well as grain to maintain a healthy local economy.

What evidence is there that the soil is not considered valuable near where you live?
Much of the land is covered with concrete. You find bare spaces in lawns, parks, around businesses or schools. Garbage is stored on the land. People or businesses dump chemicals and non-degradable wastes on the ground. People don't use farming and gardening methods such as crop rotation, contour farming, and terracing to conserve and protect the soil.

  • What are you going to do to protect and conserve the small amount of topsoil left to grow all the plants to feed the more than 6 billion people and all the animals in their care?