Nitrogen Cycle

TEKS 12 a

Objectives

1. Analyze the flow of energy through the Nitrogen Cycle and Phosphorus.

2. Analyze changes caused by human and natural occurrences in these two cycles.

What is Nitrogen?

Nitrogen is a chemical element. Look at the periodic table at the front of the room.

1. What group is carbon in? ________

2. What is the atomic mass? ________

3. How many protons? __________

What is Nitrogen?

Where can we find nitrogen?

Since it is odorless, colorless and tasteless, we often don’t realize that nitrogen is ALL around us.

Raise your hand if you know what percentage of the air around you is Nitorgen….

Did you guess it??

•75

Nitrogen Cycle

Nitrogen is important to all life!!

From the depths of the ocean ….

Nitrogen Cycle

To the atmosphere around us…

Nitrogen Cycle

We know Nitrogen is found in the air, but where are some other places we can find it?

1. In living Tissue

2. In proteins

3. In chemicals (ex: ammonia, nitric acid)

Nitrogen Cycle

Nitrogen in the atmosphere cannot be used by most organisms. It has to go through a special process first.

Nitrogen Cycle

Nitrification- Changing NH4 into NO2 or NO3

What does this mean??

Bacteria + Ammonia Usable Nitrogen for Plants and Animals

Nitrogen Cycle

Plants need nitrogen to grow, develop and produce seed.

The main source of nitrogen in soils is from organic matter.

Organic matter can be plant and animal residues.

Nitrogen Cycle

The nitrogen in organic matter is largely in organic forms that plants cannot use.

Based on what you have learned so far, what process has to happen before plants can use the nitrogen?

Nitrification….

Bacteria found in soils convert organic forms of nitrogen to inorganic forms that the plant can use!

Nitrogen is taken up by plant roots and combined into organic substances in the plant, such as enzymes, proteins and chlorophyll.

Nitrogen Cycle

When the plants die, that organic material goes back into the soil and it may be converted again!

How does nitrogen leave the soil other than through plants?

Nitrogen Cycle

Denitrification-Bacteria change nitrate in the soil to atmospheric nitrogen, which joins the atmosphere.

RunoffCarries the nitrogen in fertilizers and manure and the nitrogen in the soil into our rivers and streams -- a concern for water quality.

Nitrogen Cycle

Another way nitrogen enters the cycle is as inorganic nitrogen from the atmosphere and factories.

• Make a thinking map to show the steps of the nitrogen cycle

• You may include: pictures, labels and descriptions.

• The next slide will help you…

Nitrogen Cycle

1. Cyanobacteria & Rhizobium take nitrogen from air(nitrogen fixation)

2. Convert Nitrogen Gas into ammonia

3. Nitrifying bacteria in soil change ammonia into nitrates

4. Plants absorb and use nitrates to make proteins

5. Consumers eat plants and get proteins containing nitrogen

6. Decomposers break down organic material and release nitrogen to the air (called ammonification)

7. Anaerobic bacteria in soil release nitrogen from nitrates into the air (called denitrification)

Phosphorus Cycle