The Ground Beneath Our Feet

S6E5h. Describe soil as consisting of weathered rocks and

decomposed organic material.

What Makes Up Healthy Soil?

• Mineral fragments, humus, air, water, and living things such as–Plant roots, Insects, Worms

• Humus–Organic Material–Can support the growth of vegetation

• Parent rock– The source of mineral fragments in the soil

Soil Formation• Soil starts out as rock

• The surface rock breaks down into smaller pieces and is mixed with organic matter.

• Over time this creates a thin layer of soil.

• Decaying matter makes the soil thick and rich

Soil Particles

Different Types of Soil• Every soil type is a

mixture of sand, silt, clay.

• The right mixture is called loam.

• Loam = • 40% sand• 40 % silt• 20 % clay

Soil Profile• The vertical display of soil

horizons.

• Each soil profile is different from another.

• http://courses.soil.ncsu.edu/resources/soil_classification_genesis/soil_formation/soil_transform.swf

What is a Soil horizon?• O- Litter from dead plants &

animals• A– Topsoil

• E– Zone of intense leaching.

• B– Collects dissolved

substances from upper horizons

• C– Weathered bedrock

• R– Bedrock

Review Questions1. Which particle is the biggest one that goes

in soil?

– A. Clay

– B. Silt

– C. Quartz

– D. Sand

Review Questions2. Horizon C is made mostly of

– A. Humus

– B. Organic Material

– C. Bedrock

– D. Weathered Rock

O

C

B

A

Review Questions3. What is loam?

– A. Loam is the perfect mixture of 40 % sand, 40% silt, and 20 % clay.

– B. Loam is the combination of 30% sand, 40% mud, and 30% clay.

– C. Loam is located in horizon B.

– D. Loam is the particle quality of any soil.

Review Questions4. What is missing from this profile?

– A. Humus

– B. Organic Material

– C. Bedrock

– D. Weathered Rock

O

C

B

A

Review Questions

5. How does soil start?

- A. A large rock is weathered

- B. Bits & pieces of rocks are cemented together

- C. Decaying matter is compacted together

- D. None of the above

Review Questions1. Which particle is the biggest one that goes in soil?– A. Clay

– B. Silt

– C. Quartz

–D. Sand

Review Questions2. Horizon C is made mostly of

– A. Humus

– B. Organic Material

– C. Bedrock

–D. Weathered Rock

O

C

B

A

Review Questions3. What is loam?

– A. Loam is the perfect mixture of 40% sand, 40%silt, and 20% clay.

– B. Loam is the combination of 30% sand, 40% mud, and 30% clay.

– C. Loam is located in horizon B.

– D. Loam is the particle quality of any soil.

Review Questions4. What is missing from this profile?

– A. Humus

– B. Organic Material

– C. Bedrock

– D. Weathered Rock

O

C

B

A

Review Questions

5. How does soil start?

- A. A large rock is weathered

- B. Bits & pieces of rocks are cemented together

- C. Decaying matter is compacted together

- D. None of the above