Soil Properties

Foundation Science 4 Class Code SC22102

What is Soil made of?Soil is made of:1) mineral particles 2) organic matter 3) water 4) air

When insects, worms, bacteria, and fungi and other organisms die they decay and form a material called “humus”.

As more organisms die, the soil becomes more fertile.

The Organic Matter in Soil is Mostly Humus

Much of the life on earth depends on soil

Soil provides the nutrients needed by most plants to grow.

Why is Soil Important?

Soil is just as important as water, air, and sunlight.– Without soil, there would be no plants.– Without plants, there would be no food, shelter or

oxygen to breathe for humans or animals.

How are Soils Formed?1. Decomposition –

animals and plants die and “feed” the soil

How are Soils Formed?1. Decomposition2. Weathering (not

moving)– rain and wind break rocks down into soil

How are Soils Formed?1. Decomposition2. Weathering3. Erosion (moving)–

when the rocks break and fall apart in the wind or rain

Soil Profiles

• Soil forms in layers.• The set of layers is

called a profile.

Soil Profiles

• Sometimes the layers are called horizons.

Types of SoilThree Types:

1) Sandy soil contains large particles. Sandy soils stay loose and allow moisture to penetrate easily, but do not retain it for long term use.

2) Loam soil is a mix of sand, silt or clay, and organic matter. Loam soils are loose and look rich.

3) Clay soils are made of very small particles. They feel slick and sticky when wet.

Clay Soil is Slippery and Holds Water Up

Remember, the particles in clay soil are very small

Sandy Soil does NOT Hold Water

Sandy soil has large particles and holds air but not water

Loam Soil holds both Air AND Water

Loam soil has both large and small particles and holds water and air well

All Three Soils…

Clay SoilSandy Soil

Loam Soil

What do Plants Need to Grow?1. Air2. Water3. Nutrients4. Sunlight

Soil responsible for these 3

So, if soil does not have a lot of air, plants won’t grow well.This is why clay soils are bad for plant growth.

If soil does not have a lot of water, plants won’t grow well.This is why sandy soils are bad for plant growth.

Loam soils can hold water and air, and are the best for plant growth.

Types of Soil Video

Questions1. What is soil made of?2. What is humus? 3. What are 2 reasons why soil is important?4. How are soils formed?5. What is a soil profile ?6. What are the 3 types of soil?7. Which soil is best for plant growth?8. What are the 4 things a plant needs to grow?9. A plant needs 4 things to grow, how many does it get from soil?10. Why are clay soils bad for plants to grow?11. What is sandy soil good at holding?12. What soil type is probably under this water?