Soil
What is Soil?
It is the top layer of the ground where plants grow.
Why Soil is Important.
Plants grow in it.
Holds water and nutrients.
How Many Layers Are There in Soil?
Most soil profiles have 4 main layers.
1. Topsoil.
2. Subsoil.
3. Parent Material.
4. Bedrock.
Why Soil Has Layers.
Soil starts forming at the surface where rocks break down and plants grow.
Over many years, new material builds up on top, while older material stays below, making layers.
Main Types of Soil.
There are 4 main types of soil.
1. Sandy Soil.
2. Clayey Soil.
3. Silt Soil.
4. Loam Soil.
How Soil Is Formed.
Soil is formed from rocks over a very long time.
Why Does Soil Take So Long to Form?
1. Rocks break very slowly.
Rocks are hard and strong.
Wind, rain, sun, and ice only break a tiny bit at a time.
2. Weather happens slowly.
Sun heats rocks during the day.
Night makes them cold.
This slowly cracks the rocks over many years.
Rain drops hit rocks and break very tiny bits.
3. Dead plants take time to rot.
Trees, leaves, and animals don’t turn into humus quickly.
Decomposition takes time because microbes and worms work slowly.
4. Layer by layer builds slowly.
Soil forms little by little.
Because new material forms only at the top surface.
Fun Fact.
It takes almost 1,000 years to make just 1 centimeter of soil.