Soil. Soil is… A combination of weathered rock (sediments), humus (decaying organic matter such as dead plants and animals), air and water.

Soil

Soil is…

• A combination of weathered rock (sediments), humus (decaying organic matter such as dead plants and animals), air and water

In order for soil to form…

• Bedrock weathers into sediments

And

• Organic matter (dead plants and animals) decay to form humus.

Sediments and humus mix

Quiz your partner

• What does soil contain? • How does it form?

The Nitrogen Cycle

• Healthy soil contains Nitrogen for plants to absorb into their roots.

Animals eat plants to get Nitrogen

• Nitrogen makes proteins. So when you eat protein you are eating Nitrogen.

Protein

• Every structure in a living organism is made of protein…your DNA, cells, eyes, everything!

• So, organisms need protein and the Nitrogen to live.

Quiz your partner

• Why is Nitrogen important? • How do plants get it? • How do animals get it?

Nitrogen is now in plants and animals

• When the plant or animal dies, this Nitrogen returns to the soil through decomposition.

• Manure

The air is mostly Nitrogen

• Nitrogen in air gets into the soil through Nitrogen Fixing.

• Nitrogen Fixing bacteria in roots can change Nitrogen in the air into Nitrogen in the soil.

• Lightening can also fix Nitrogen.

Quiz your partner

• How does get Nitrogen get into the soil (there are four ways)?

Nitrogen returns from soil to the air

• Bacteria can change the Nitrogen in the soil back into Nitrogen in the air.

It is a cycle-draw and put your notes into the cycle

Quiz your partner

• Describe the entire Nitrogen cycle from the Nitrogen in the air to the soil to the plants, to the animal, back to soil and back to air.