The Nitrogen Cycle

2 ~ SampaguitaGroup 6

Celz Alejandro Jade Castro Josh Quinto

Cheska Regalado Geo Robeniol

What is Nitrogen?

Nitrogen (N) is an essential component of DNA, RNA, and amino acids.

All organisms require nitrogen to live and grow.

Majority of the air we breath is N2. (78%)

Most of the nitrogen in the atmosphere is unavailable for use by organisms.

What is Nitrogen?

In order for plants and animals to be able to use nitrogen, N2 gas must first be converted to more a chemically available form.

Biologically available nitrogen is usually short of supply in natural ecosystems, limiting plant growth and biomass accumulation.

The Nitrogen Cycle

This describes the movement of N2 between the atmosphere, biosphere, and the lithosphere in different forms.

Nitrogen is processed and exchanged in the various storage pools.

The processes in this cycle include nitrogen fixation, nitrogen uptake, nitrogen mineralization, nitrification, and denitrification.

Nitrogen Fixation

N2 → NH4+

A process in which Nitrogen is converted to ammonium.

Done mostly by Nitrogen fixing bacteria in legume roots

Done by human activities such as burning fossil fuels and use of synthetic nitrogen fertilizers.

Nitrogen Uptake

NH4+ → Organic N

Ammonia is incorporated into protein and other organic nitrogen compounds.

This is done, for example, by organisms when they eat. They use nitrogen that has been initially fixed by nitrogen fixing bacteria.

Also known as Organismic Growth

Nitrogen Mineralization (Decay)

Organic N → NH4+

Organic Nitrogen is converted back to ammonium when organisms die.

This is done by decomposers which consume organic matter in the process of decomposition.

Nitrification

NH4+ → NO3- or NO2-

Ammonium is transformed into nitrate or nitrite.

Ammonium is positively charged so it “sticks” to soil and is not leached easily unlike nitrate (NO3-) and nitrite (NO2-)

Denitrification

NO3- or NO2- →N2 + N2O

Oxidized forms of nitrogen are turned to into dinitrogen and sometimes, nitrous oxide gas.

Done by denitrifying bacteria.

Denitrification returns Nitrogen to the atmospehere.

Remember.....In the Nitrogen Cycle, nitrogen undergoes chemical reactions, changes form, and moves through different reservoirs on earth.

Nitrogen is needed by organisms as it is the essential component of Amino Acids.

The Five processes – Fixaton, Uptake, Mineralizatoin, Nitrification, and Denitrificaton - are mostly driven by microorganisms.

Humans influence this biogeochemical cycle with the ise of nitrogen-based fertilizers.

Quiz

1.) What is the most common way that nitrogen fixation occurs?

a. Lightning

b. Nitrogen Fixing Bacteria

c. Fossil Fuels

d. Forest Fires

Quiz

1.) What is the most common way that nitrogen fixation occurs?

a. Lightning

b. Nitrogen Fixing Bacteria

c. Fossil Fuels

d. Forest Fires

Quiz

2.) Atmospheric Nitrogen is easily taken up and used by organisms.

a. True

b. False

c. I don't know

d. Tralse?

Quiz

2.) Atmospheric Nitrogen is easily taken up and used by organisms.

a. True

b. False

c. I don't know

d. Tralse?

Quiz

3.) Organic nitrogen is converted back to inorganic nitrogen like ammonium in the process of ____

a. Nitrogen Fixation

b. Nitrification

c. Nitrogen Mineralization (Decay)

d. None of the above

Quiz

3.) Organic nitrogen is converted back to inorganic nitrogen like ammonium in the process of ____

a. Nitrogen Fixation

b. Nitrification

c. Nitrogen Mineralization (Decay)

d. None of the above

Quiz

4.) Ammonium (NH4) stays in soil, while nitrate (NO3) is easily leached out. Why do they behave so differently?

a. NO3 is easily carried by bacteria

b. NH4 has a positive charge

c. NH4 is unavailable to organisms

d. None of the above

Quiz

4.) Ammonium (NH4) stays in soil, while nitrate (NO3) is easily leached out. Why do they behave so differently?

a. NO3 is easily carried by bacteria

b. NH4 has a positive charge

c. NH4 is unavailable to organisms

d. None of the above

Quiz

5.) Which process releases dinitrogen gas (N2) back into the atmosphere?

a. Denitrification

b. Nitrogen Fixaton

c. Nitrogen Mineralization (Decay)

d. Nitrification

Quiz

5.) Which process releases dinitrogen gas (N2) back into the atmosphere?

a. Denitrification

b. Nitrogen Fixaton

c. Nitrogen Mineralization (Decay)

d. Nitrification

Quiz

6.) Once bacteria have fixed nitrogen, it can be taken up by plants and animals, where it is used in the production of ____

a. Nitrogen oxides

b. Carbohydrates

c. Proteins

d. Energy

Quiz

6.) Once bacteria have fixed nitrogen, it can be taken up by plants and animals, where it is used in the production of ____

a. Nitrogen oxides

b. Carbohydrates

c. Proteins

d. Energy

Quiz

7.) Synthetic fertilizers add ____ to the soil.

a. Fixed nitrogen (Ammonium)

b. Organic Nitrogen

c. Nitrogen Oxides

d. Nitrate

Quiz

7.) Synthetic fertilizers add ____ to the soil.

a. Fixed nitrogen (Ammonium)

b. Organic Nitrogen

c. Nitrogen Oxides

d. Nitrate

Quiz

8.) Legumes host nitrogen fixing bacteria and, thus are good crops to replenish the soil.

a. True

b. False

c. I don't know

d. Tralse?

Quiz

8.) Legumes host nitrogen fixing bacteria and, thus are good crops to replenish the soil.

a. True

b. False

c. I don't know

d. Tralse?

Thanks, Bye!