Types of soil

• newEditor
• Biology
• Lower Secondary (Key Stage 3)

Surface of the earth

What is the surface of the earth made up of?

Humus

Topsoil

Subsoil

Weathered rock fragments

Bedrock

Which layer of the soil is composed of partially decayed plant and animal matter?

A

Parent rock

B

Organic matter

C

Subsoil

D

Humus

Which layer of the soil is directly affected by weathering of the underlying bedrock?

A

Organic matter

B

Hummus

C

Subsoil

D

Topsoil

Which layer of the soil contains the highest concentration of organic material and microorganisms?

A

Subsoil

B

Bedrock

C

Topsoil

D

Parent rock

Which layer of the soil is composed of weathered rock fragments?

A

Topsoil

B

Hummus

C

Parent rock

D

Organic matter

Surface of the earth

• The surface of the earth is called the crust.

soil

air

water

sunlight

• It consists of rocks (even under the ocean) and soil.

• Life on earth is supported by:

• Soil comes from rocks.

Surface of the earth

• The land is made up of topsoil, subsoil, and rocks.

• If it weren’t for soil, there’d be no life on earth.

• Topsoil lies on the surface.

Surface of the earth

• Topsoil takes an extremely long time to form – approximately 100 years per inch of topsoil.

• It consists of broken-down rocks and decaying plant and animal matter.

• It supports plant life.

Types of soil:

Sandy

Clayey

Loamy

Surface of the earth

• Made up of mostly sand (70%); the rest is clay and silt.

• Large amounts of course sand grains.

Sandy Soil

Surface of the earth

Sand under a microscope

Does not hold water very well

What color is sandy soil?

A

Red

B

Brown

C

Yellow

D

Black

• Large proportions of clay particles; the rest is humus and silt.

• Clay is so compact that it cannot trap air.

• It’s sticky and slippery when wet and hard when dry.

Clayey Soil

Surface of the earth

Holds lots of minerals!

What color is clay soil?

A

Black

B

Yellow

C

Red

D

Brown

• Has an equal mix of sand, silt, and clay.

• Contains humus (decomposed plant and animal matter).

• Ideal soil composition for most garden plants.

Loamy Soil

Surface of the earth

Has lots of nitrogen!!

Which soil texture is a mixture of sand, silt, and clay?

A

Peat

B

Clay

C

Sandy

D

Loam

Fun Facts!

Sandy soil comes in many colours.

Clayey soil particles are so small that they hold an electrical charge.

Loamy soil holds the most nutrients.

This nutrient is nitrogen

Surface of the earth

Which nutrient is most available in loamy soil?

A

Nitrogen

B

Calcium

C

Phosphorus

D

Potassium

Which soil texture has the best nutrient availability?

A

Loam

B

Sandy

C

Clay

D

None

Soil also has water, air, and dead and living organisms in it. Can you think of anything that lives in soil?

Fungi

Beetles

Earthworms

Snails

Ants

Larvae

Millipedes

Burrowing mammals

Bacteria

Tree and plant roots

Surface of the earth

Which organisms are likely to be found in the subsoil layer of the soil?

A

Earthworms

B

Subterranean insects

C

Grasshoppers

D

Ladybugs

Which organisms are likely to be found in the topsoil layer of the soil?

A

Bacteria

B

Fungi

C

Birds

D

Snakes

Which organisms are likely to be found in the humus layer of the soil?

A

Springtails

B

Decomposers

C

Rabbits

D

Moles

Topsoil forms very slowly in nature, so, we need to conserve it.