The Nitrogen

Cycle

BSE11

There is an abundance of nitrogen in the atmosphere. It makes up 80% of the total volume of air. Neither plants nor animals can use nitrogen directly from air. It is the fourth element found in living things.

The nitrogen cycle describes how nitrogen moves through different objects including in the atmosphere and the ground. Because nitrogen must be fixed in order to be used by living things, it rarely exists in its pure form. Bacteria are very important part of the nitrogen cycle because it helps to change or fix nitrogen into a usable form.

Trivia Time! Plants absorb nitrogen directly from the

soil. There are many steps in the nitrogen cycle

including fixation, nitrification, assimilation, ammonification, and denitrification.

Plants need nitrogen to make chlorophyll which they use during photosynthesis.

Nitrogen is important to animals in many ways including being a part of its DNA and proteins.

Humans alter the nitrogen cycle by using synthetic fertilizers on lawns which adds to much extra nitrogen to the soil.

Nitrous oxide is a greenhouse gas in the atmosphere.

Too much nitrous oxide in the atmosphere can cause acid rain.

Nitrogen is used by many farmers as a fertilizer which helps plants grow.

FOUR PRINCIPAL STAGES OF NITROGEN CYCLE

NITRIFICATION

ASSIMILATION

AMMONIFICATION

DENITRIFICATION

NITRIFICATION

This is the process by which ammonium gets changed into nitrates by bacteria. Nitrates are what the plants can then absorb.

ASSIMILATIONThis is how plants get nitrogen. They absorb

nitrates from the soil into their roots. Then the nitrogen gets used in amino acids, nucleic acids, and chlorophyll.

AMMONIFICATION• This is part of the decaying process. When a plant or animal dies, decomposers like fungi and bacteria turn the nitrogen back into ammonium so it can reenter the nitrogen cycle.

DENITRIFICATION• Extra nitrogen in the soil gets put back out into the air. There are special bacteria that perform this task as well.

Plants and animals could not live without nitrogen. It is an important part of many cells and processes such as amino acids, proteins, and even our DNA. It is also needed to make chlorophyll in plants, which plants use in photosynthesis to make their food and energy. 

Why is nitrogen important to life? 

How have humans altered the cycle?Unfortunately, human activity has altered the cycle. We

do this by adding nitrogen into the soil with fertilizer as well as other activities that put more nitrous oxide gas into the atmosphere. This adds in more nitrogen than is needed by normal cycle and upsets the cycle's balance.

Ecosystem:The Nitrogen Cycle

This picture shows the flow of the nitrogen cycle. The most important part of the cycle is bacteria. Bacteria help the nitrogen change between states so it can be used. When nitrogen is absorbed by the soil, different bacteria help it to change states so it can be absorbed by plants. Animals then get their nitrogen from the plants. 

References

• Ordanez J.A II . “Environmental Biology : Philippine Setting” (2008) . Retrieved June 25, 2014.

• “Nitrogen” . Retrieved June 25, 2014http://www.chemicool.com/elements/nitrogen.html

• “Ecosystem: The Nitrogen Cycle” . Retrieved June 25, 2014

http://www.ducksters.com/science/ecosystems/nitrogen_cycle.php

• “Nitrogen Cycle Facts” . Retrieved June 25, 2014http://www.softschools.com/facts/earth_systems/nitrogen_cycle_facts/409/

• Real Trees 4 Kids. “Cycles”. Retrieved June 25, 2014.http://www.realtrees4kids.org/sixeight/cycles.htm