Nitrogen Cycle

The nitrogen cycle is how nitrogen moves through the atmosphere.

The nitrogen cycle uses different things to move the nitrogen around.

Nitrogen is important to anything that is living on the Earth.

Unlike oxygen, nitrogen is not absorbed from the air by plants or animals.

How Does Nitrogen Move?

Nitrogen moves through different things such as:

• Animals
• Bacteria
• Plants
• Air
• Ground
• Soil

Different States of Nitrogen

Nitrogen has different forms on the Earth.  There are different states of the nitrogen such as:

• Nitrates which are NO2
• Ammonium which is NH4
• Nitrogen that is found in the atmosphere which is N2

How Does the Nitrogen Cycle Work?

In order for the nitrogen cycle to work, the most important part is bacteria.

Bacteria helps the nitrogen to change to different states so that it can be used in the right way.

Soil, for example, has bacteria that helps the nitrogen be broken down so that it can be absorbed.

Animals get nitrogen from the plants.

Development of the Nitrogen Cycle:

There are different steps in the nitrogen cycle and these steps include:

• Fixation
• Nitrification
• Assimilation
• Ammonification
• Denitrification

Fixation is when bacteria turns nitrogen into ammonium so that it can be used by plants.

Nitrification is the process where bacteria changes the ammonium to nitrates and the plants absorb these nitrates.

Assimilation is when the plants absorb the nitrates from the soil and from their roots.  The nitrogen is then used for chlorophyll, nucleic acids and amino acids.

Ammonification is when the plant or animal dies and the decomposers turn the nitrogen back into ammonium and then it returns to the nitrogen cycle.  Remember that decomposers are bacteria and fungi.

Denitrification is when bacteria sends more nitrogen into the soil and the nitrogen is released into the air.

What Makes Nitrogen So Important?

People, plants or animals cannot live without nitrogen.

Nitrogen helps to make up cells and helps to produce things such as proteins, amino acids and other things that are needed for our bodies.  Many of the things that nitrogen produces are found in our DNA.

Another reason that nitrogen is so important is that it is needed by animals, plants and people because it helps to build things in our bodies that are the building blocks of life.

Nitrogen also helps with the process of chlorophyll which is needed for photosynthesis to help plants grow.

Stages of the Nitrogen Cycle:

• Nitrogen goes into the air and is changed to nitrates by lightning.
• Precipitation takes nitrogen to the soil.
• Nitrogen in the soil is changed to nitrates because of bacteria.
• The plants absorb the nitrates through their roots, and it helps them to grow.
• Animals eat the plants and they absorb the nitrates and turn it into animal proteins that help them to grow strong and healthy.
• Nitrogen is returned to the soil when animals go to the bathroom and when bacteria breaks down the dead bodies of plants and animals.

How is the Nitrogen Cycle Harmed?

The nitrogen cycle gets changed when people add fertilizers to the soil.

Since fertilizers have nitrogen in them, adding it into the fertilizer causes the plants to release a gas called nitrous oxide.

When adding more nitrogen to the Earth, it causes more nitrogen than is needed into the Earth and changes the nitrogen cycle.

Facts About the Nitrogen Cycle:

• 78% of the Earth’s atmosphere is made up of nitrogen.
• Most of the nitrogen found in the atmosphere is not able to be used by plants or animals.
• Nitrogen is used in fertilizer.
• Fertilizer helps plants to grow faster.
• Nitrous oxide is a greenhouse gas.
• Too much nitrous oxide can cause there to be acid rain.
• Nitrogen has no color or odor.
• Nitrogen has no taste.
• Nitrogen is used in explosives.
• Our bodies are made up of around 3% nitrogen.

What Did You Learn?

• What is the nitrogen cycle?  The nitrogen cycle is when nitrogen moves from the air to the soil and from the soil to living things and then from the living things back into the soil and the air.
• How many steps are there to the development of nitrogen?  There are five steps to the development of nitrogen.
• How does nitrogen get back into the soil?  Nitrogen gets back into the soil through bacteria decomposing dead things and when animals use the bathroom on the ground.
• Why is nitrogen important?  Nitrogen is important because it helps to give life to animals, plants and people.  Nitrogen is an important part of the building blocks of our bodies and even makes up part of our DNA.
• What is one of the most important parts of the nitrogen cycle?  Bacteria is one of the most important parts of the nitrogen cycle because it helps to break down dead things and give nitrogen to the soil and air.

• Back to – Earth Science