Do Now

In your own words, describe what soil is and

what it’s made up of.

Aim

• How do our activities help or

prevent soil formation?

Soil• Weathered down rock material and organic

matter • Produced by weathering and biological activity

Humus• Top layer

• A dark, organic material found in soil

• made from the decayed remains of plants and animals

• makes soil fertile

Bedrock

• Solid, unweathered rock that lies beneath the soil

Parent Rock

• The rock from which the soil was made from

• Determines the type of soil– Transported Soil

• Came from somewhere else;different composition than bedrock its on

– Residual Soil• Rests on top of its parent rock; same

composition as bedrock its on

Soil Profile• Side view that shows layers of the soil and

the bedrock beneath– Layers are called horizons

Soil Profiles

1. What role does weathering play in the formation of soil?

• Soil forms as rock is

weathered (clay, sand, silt) and

mixes with humus.

2. What is soil made of?

a. Weathered rock pieces provide minerals

b. Humusc. Air – the soil is aerated

when worms dig holes d. Water

3. How do plants and animals help the formation of soil?

a. Organisms (like worms) mix the soil and make spaces in it for air and water.

b. Microbes (decomposers) decay dead organic matter.

Soil profile: Layers are called horizons

A:Top Soil: Organic and small rock materials, Humus, minerals, most fertile, organisms live here

B: Subsoil: little organic matter; minerals leached from A

C: Partly weathered bedrock, first stages of mechanical &chemical change

D: Un-weathered bedrock

4. Why is the bedrock un-weathered?

There is little water, animals, wind, and ice to cause weathering down that deep in the ground.

A

B

C

darker

lighter

• Which layer contains the most biological material and why?

• Why is layer D mostly unweathered bedrock?

What factors increase the rate of soil formation?

• Climate (water and temperature)– Soil formation happens faster in warm, damp climates

• Rock type (size and composition)– Softer rocks will break down faster

…just like weathering rocks!

Factors that affect soil formation

Leaching – surface water and rain carries

dissolved minerals to lower layers of soil.

Why is soil important?

a. All living organisms depend directly or indirectly on plants (producers) that grow in soil.

b. It takes a very long time to form, soil needs to be conserved. It is not easily renewable….soil is limited.

How is soil eroded?

• Removal of vegetation (grass, shrubs) that holds the soil in place.

• Desertification- Drought dries out the soil turning it to dust; easily eroded by wind

How can we encourage soil formation?

a. Composting – pile up grass clippings, leaves, vegetables and newspapers to create a fertile pile of soil

b. Mulching lawn clippings and leaving them on the ground

Closure• What kind of soil does Long Island have?• In which horizon is the soil most fertile?• What is parent rock?• How does the parent rock affect soil

composition?• Why is it important to leave leaves and

grass clippings on your lawn? • What does bagging up leaves and grass

do?

Brainpop - soil

• http://www.brainpop.com/science/earthsystem/soil/