Soil
|
Soil
|
|
Soil or dirt is made up of different things. These things are crumbling rocks, rotting plants, and bones. It can take hundreds of years for soil to form, because it takes that long for the rocks to be worn down into tiny bits.
It takes a long time for soil to form. Rocks have to break down, and mix with rotting leaves and other material. To get one inch of soil, it takes 500 to 1,000 years!
Over that time, sediment (types of soil) piles up in different layers. Each layer has a special name and special job.
Humus – fluffy and dark brown, insects and worms live here Topsoil – rich brown, holds plant roots Subsoil – red or yellow, heavy and hard to dig in Parent material or bedrock– rocks and sediments, rocky and hard
Picture used with permission from Pics4Learning
There are over 100,000 different types of soil in the world. Scientists study soil to see what it’s made of and how it can be used. Some soil is used for farming. Other is used to make foundations for roads.
Soil is an important resource for all life on Earth. Plants and trees must have soil to live. Without plants, people and animals would not have food or oxygen. We have to be careful to take care of our plants and soil.
Lots of little critters live in soil. Worms and beetles and other bugs live in the dirt. They are called decomposers. Decomposers eat the dead plants and then leave droppings which have vitamins and make the soil richer.
Earthworms have to swallow dirt to get their food. When the dirt comes back out of the worms, it’s fluffy and loose and has a lot of nutrients in it for the plants. Earthworms are very valuable to our ecosystem.
Have you ever wondered why you see worms come out of the soil after it rains? Rainwater fills up little empty spaces in the soil, and the worms have to come out to breathe.
Other animals like moles, mice, and shrews dig underground and help loosen the soil. Some animals like woodchucks, skunks, and chipmunks sleep in underground burrows.
Humus, air, and water are all found in the top layer of soil. It’s called topsoil because it is on top of all the other dirt. Topsoil can get blown away by wind or washed away by rain. The roots of plants help hold it together.
Try this: Put some soil into a glass jar and then fill it with water. Stir it up and wait for a few minutes, and you will see the soil separate. You will have layers of different kinds of soil. The rocks and pebbles should fall to the very bottom because they are the heaviest. On top of that you will find sand, silt, and clay. These are all tiny pieces of rock and aren’t quite as heavy. Sand will be on top of the other layers.
To learn more about soil, visit this web site: http://www.factmonster.com/ce6/sci/A0845818.html.
|
|
|
