Understanding Soil Composition and Layers

Why is soil essential for plants and trees?

• It protects them from animals.

• It offers a place for roots to anchor and nutrients to grow.

• It provides them with sunlight.

• It gives them oxygen.

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What percentage of soil is composed of minerals?

• 25%

• 35%

• 5%

• 45%

Which component of soil is present in the smallest percentage?

• Air

• Minerals

• Water

• Organic matter

What is a soil profile?

• A horizontal layer of soil.

• A vertical layer of soil showing different layers.

• A type of soil found in deserts.

• A soil type rich in minerals.

What is the O horizon also known as?

• Bedrock

• Topsoil

• Subsoil

• Litter layer

What does the O horizon primarily contain?

• Dead leaves, twigs, and fallen trees

• Rich organic matter

• Sand and silt particles

• Clay and rock fragments

What is another name for the A horizon?

• Bedrock

• Litter layer

• Topsoil

• Subsoil

What is humus?

• A type of mineral found in soil

• Dark organic material formed from decayed plant and animal matter

• A layer of sand and silt

• A type of rock fragment

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What is the E horizon also called?

• Eluvial layer

• Topsoil

• Subsoil

• Parent material

What happens in the E horizon?

• Dead leaves and twigs accumulate.

• Rock fragments are formed.

• Water removes substances, concentrating sand and silt.

• Organic matter accumulates.