Science of Life Explorations

Let’s Learn About Soil:

What is Soil?

What is soil?

Is soil dirt?

How is soil formed?

What does organic mean?

What is in soil?

How can we collect soil?

Can soils be different? Why?

What can we learn by examining soil?

Why is soil important?

Is soil part of the food chain?

Compare the two photographs of soil. What makes them different?

What is soil?

Soil is a thin covering of land areas on the earth’s surface. It has many sizes of PARTICLES, and is made up of MINERALS, ORGANIC MATERIAL, water and air. It is important to all living creatures.

Is Soil Dirt?

You might think that dirt and soil are the same things. But soil is the substance plants grow in. Dirt or ‘dirty’ means something is not clean. When an adult says your room is dirty, it doesn’t mean it is full of soil. Your hands may become dirty by playing in the soil.

Just remember to use the term soil to describe the useful part of the earth’s surface needed for plant growth. Plants use soil for NUTRITION, water, OXYGEN and stability. Now that you are older, you can understand the difference.

Soil covers much of the land on earth.

What covers most of the earth’s surface?

How is soil formed?

Soil is formed from large rocks that have broken down over time by forces of nature. There are many types of soil, each with different colors and textures. These are called soil properties. Can you see layers in the soil ‘profiles’ below?

One soil profile is from New

York State. One is from

Florida. Do you see a difference?Which one

is from New York?

A soil profile is a way to look at the layers in soil. When someone digs a hole in the ground, you may see the difference in these layers. In New York State, the soil closest to the surface is usually darker. We will learn why. Can you guess?

New York state is a great agricultural state because we have good soil for plants.

Sand

Silt

Clay

fungus bacteria

Soil is formed slowly as rocks break down into tiny pieces, through EROSION. Organic material decays and mixes with INORGANIC MATERIALS and water to form soil. Soil even has air in it!

Soil is layered. The upper layer or SOIL HORIZON has more organic matter and water, causing it to be darker. Plant roots use this area to get nutrition, water and oxygen.

Soil is described by its particle size. All soil is made up of sand, silt and clay. The larger or ‘coarser’ particles are sand. The smallest particles cling together to make clay.

What is in soil?

Does soil cover all of the earth?

yes____ no____

Is soil formed by wind and water breaking down rocks (erosion?)

yes____ no____

Circle the things that are organic: earthworms rocks leaves a dead insect

Are soils the same everywhere?

yes____ no____

Why is soil important to you?

___________________________________________________________

___________________________________________________________

___________________________________________________________

Soil is made up of three types of soil particles:

_ _ _ _, s i l t and c l a y

Bacteria: one celled micro-organisms that can be helpers to plant and human health or can cause disease

Clay: the smallest of the soil particles; when wet it is sticky and when dry it is very hard

Components: an ingredient or one of many ‘parts’ that make up something

Erosion: the wearing down of soil by wind, water, heating and freezing

Fungus: a living organism which absorb nutrition by decomposing its food source

Horizon: in soil, horizons are another name for its layers

Inorganic Matter: things that are not alive and never were, such as rocks

Magnification: using glass lenses that magnify (make things seem larger) so that small things are easier to see

Nutrition: the energy (food source) needed by living things to be able to survive and thrive

Organic Matter: things that are living or were once living (leaves are ‘dead’ but were once alive)

Oxygen: an essential element that animals and most plants need to survive; it is found in the atmosphere, the soil and in water

Parent Materials: in soil, parent materials are the types of rocks and minerals that eventually become soil over time

Particles: small parts of something, especially soil

Silt: a type of soil particle between the smallest (clay) and the largest (sand)

Surface: the top of something

Textures: the varying structure of something, such as rough or smooth

Background for teaching this lesson:

Soil covers much of the land on Earth. All soils are made up of sand, silt, or clay. This de-scribes the particle sizes, not the type of parent material it is composed of. Parent mate-rials are the types of rocks and minerals it is derived from. Soils have other components: air, water and organic matter (decomposing plants and animals). There are many types of soils, and each has different colors, textures, structure and mineral content. The depth of the soil also varies.

Soil is formed slowly as rock breaks down into tiny pieces near the Earth’s surface. This is called erosion and results from the affects of wind, water, geological movement and freezing and thawing. Most soil has some amount of organic matter, which decays and mixes with inorganic materials (rock particles, minerals) and water to form the makeup of each particular soil. Soil is catalogued around the world, and in the United States, is mapped by type in each county and state. A soils map is available at public libraries to document the type of soils found right in your neighborhood.

Soil is layered (horizons); the upper A Horizon has more organic matter, water and air. This is good for plants. The lower layers tend to be less ‘broken down’, with less organic matter, air and water.

New York is a great agricultural state because we have good soils for plants.

Once students understand the nature of soil, they may see a difference between soil and dirt. Remind them that plants grow in soil, and that it is an intricate environment of living and non-living things.

An important property of soil is active, living soil microorganisms such as bacteria, fungi (fungus) and mites. Some things can be seen with a hand lens or magnifying lens. We can only see bacteria with a microscope. Soil Fungus – good fungi help plants get nutrients from the soil. Mites - soil mites eat good and bad fungus. They carry bacteria around on their backs! They are an important part of healthy soil. Bacteria – Bacteria can be good or bad. 1000 bacteria can fit on the head of a pin. They decompose other elements of the soil into nutrients. When you smell “soil” in the springtime, you are smelling bacteria at work after a long winter!

Spiders, beetles, earthworms, ants and many other arthropods are some of the visible members of the soil community.

Soil is important to every living creature on earth. All living things need an energy source; a majority of it is based on plant life at the bottom of the food chain. Poor soils do not contain minerals needed by plants and other living creatures. Healthy soils pass on minerals to plants, which pass them on to us! Soil must be cared for!

For Teachers and Parents:Pg. 1 Read the soil questions in a group setting, then have a discussion about the photographs. Students may recognize that the top photo shows rich farm soil supporting a new crop. The bottom photo is probably from the western U.S. The farm soil is dark and rich and probably has a lot of moisture in it, as well as organic matter. The western soil may well be very rich in minerals, such as iron or copper to cause its color, but due to the arid climate and lack of organic matter such as leaves and earthworms, these soils may be considered unusable for farming.

Pg 2 Sometimes soil gets no respect! Dirt is a pretty negative word. Throughout these activities, students may start to understand the properties of and importance of soil. Soil should be protected; it is an irreplaceable resource in our lifetime, when not taken care of. The oceans cover most of the earth’s surface, and when you consider the amount of land that is covered with snow and ice, blacktop and bare mountaintops, soil becomes even more

Pg 3 Soil profiles: Each state actually has its own ‘official’ state soil. Florida’s looks a bit sandy, but we know they have a huge agricultural industry also. There are probably hundreds of soil profiles found in each state, so a dark, rich silty farm soil can be found there also.

Pg 4 Soil profiles: Each state actually has its own ‘official’ state soil. Florida’s looks a bit sandy, but we know they have a huge agricultural industry also. There are probably hundreds of soil profiles found in each state, so a dark, rich silty farm soil can be found there also.

Pg 5 You may suggest students look for a copy of the “soil triangle” in the library or online.By placing a small amount of soil sample and water into a test tube and letting it settle out, farmers, horticulturalists, geologists and engineers can estimate what percentage of the soil is sand, silt, and clay. If it is mostly clay - it’s a ‘clay’ soil of course. The prime soil for agriculture is called loam - it is a soft mix of all three, clumps when wet, but breaks apart easily unlike clay. Sand is very porous and does not retain nutrients and water long enough for most agricultural crops.

Pg 6 When discussing soil - organic refers to something that is alive or was alive. If it was never alive - such as a rock - then it is inorganic. This is a good discussion point. Is a wooden fence organic? a book? a leather glove? Trees were alive, but what about leather? Remind students that leather is a by product of animals, and because leather is part of something that was once living, it is organic. Organic items will break down due to their nature, much faster than inorganic items. This is why soil is created so slowly. A rock will sit and seem to stay the same for hundreds of years.

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Student Lesson: Let’s Learn about Soil: What did you learn? name____________________________

Does soil cover all of the earth?

yes____ no____

Is soil formed by wind and water breaking down rocks (erosion?)

yes____ no____

Circle the things that are organic: earthworms rocks leaves a dead insect

Are soils the same everywhere?

yes____ no____

Why is soil important to you?

___________________________________________________________

___________________________________________________________

___________________________________________________________

Soil is made up of three types of soil particles:

_ _ _ _, s i l t and c l a y

Are air and water in soil?

yes____ no____

x

x

x

S A N D

Students should begin to understand that soil should be taken care of because healthy soil is the basis of plant life. Plants are the basic food source for all animals and humans, directly or indirectly.

An Apple and the Earth!

To show an example of how much soil there is on the earth, and how much of it is available for farming our crops, use this apple example:

Explain to students that 3/4 of the earth is covered with water.

Remove 3/4 of the apple. Hey, look! Both the earth and the apple have a core!

Only 1/4 or 25% of the earth is left.

But that doesn’t mean that all 25% is farmland soil waiting to be planted! Ask students what types of things on the ‘land’ part of the earth can’t be used for farming. Remind them about mountains (may be too steep to plant on, or too cold, windy or may have no soil) Snow or glaciers or ice - The globe will remind them just how much of the earth is covered with snow or ice. Deserts! Although some desert areas, like the Southwest, do support plants like cactus it does not support agriculture without amendments and significant watering. What about cities, towns and highways? Concrete, blacktop and buildings cover a lot of land!

A shocking amount of the land surface is unusable for farming due to these conditions. Remove most of what’s left and leave just a sliver to represent the 10% of the earth usable for agriculture.

(Adapted from the Natural Resources Conservation Service. Check out their website!)