Or, “How do you eat air?”

The Nitrogen Cycle

Element #7 (7 Protons, 7 Neutrons, 7 Electrons)

78% of the atmosphere is made of Nitrogen, one of the strongest bonding gases

Colorless, odorless, tastelessCreated by fusion in stars and is the

7th most common element in the Universe

What is Nitrogen?

Used in cheap light bulbs instead of argonFood preservativeFire suppression systemsAircraft tires because of lack of moistureUsed in some paintball guns (makes it

heavier and more expensive, though)Refrigerant/cryogenic (liquid nitrogen)GunpowderFertilizerPharmaceutical Drugs

Some Commercial Uses

In the atmosphere, as N2 which forms about 78% of the air we breath. Take a deep breath, but it won’t matter… it is inert. There is a million times more nitrogen in the air than nitrogen in living things.

Essential for growth and reproduction in plants and animals… 3% of your body is Nitrogen.

Found in proteins, DNA/RNA, and many other compounds essential for life.

Amino acids which are used in muscle, tissues and organs.

Urea, a byproduct of protein digestion… yes, human waste.

Nitrogen in the atmosphere can be changed to make something that we can actually use.

So, how do we turn that gas to a usable substance?

Ammonia (NH3)

Nitrogen combines with Hydrogen to make Ammonia

Nitrates (NO3)

Nitrogen combines with Oxygen to make Nitrates

Atmospheric Nitrogen

(N2)NITROGEN-CONTAINING COMPOUNDS

Animation of Nitrogen Fixation

We can’t breathe Nitrogen gas. We need FIXATIONBacteria either living on root of legumes:

AlfafaCloverPeasBeansLentilsLupinsMesquite CarobSoyPeanuts

Recap

Certain other bacteria that live “free” can convert Nitrogen gas into a usable nitrogen-containing compound, but the majority are made in nodules on roots.

Other less common ways to “fix” nitrogen are through lightning or by commercial means (making fertilizer)

When humans commercially make Nitrogen, it is sold as fertilizer

We’ll come back to this in a bit.

Animals, when eating the plants, can now take in USABLE Nitrogen compounds.

These animals are eaten by other animals and so on, up the food chain.

However it is made, once we have nitrogen fixation, the plant can now use it.

When plants and animals decompose or give off wastes, nitrogen is returned to the soil.

Bacteria and fungi break down the nitrogen-containing biotic factors and return the nitrogen compounds to the soil

During the process, some of the nitrogen compounds are converted back into NITROGEN gas, which is returned to the atmosphere.

THIS COMPLETES THE CYCLE!!!

Decomposition of organics

Nitrogen can also return to the atmosphere through emissions from cars and factories (nitrous oxides)

Volcanoes also emit nitrous oxides.

Nitrogen has a back door!

Humans interfere in the Nitrogen Cycle by doing several things:1. Burning fossil fuels and wood which releases

nitrogen compounds into the air (nitric oxide which can combine with oxygen to form Nitrogen Dioxide and eventually acid rain)

Now, back to the human factor

2. Dumping of untreated sewage and other wastewater. So much nitrogen in the waterways causes algal blooms and can quickly deplete waterways of oxygen.

3. Use of inorganic fertilizersCurrently uses about 5% of the world’s natural gas consumption (about 2% total energy in the world)

The minerals used in fertilizers are limited. Phosphorus and Potassium come from mines and Nitrates are made with fossil fuels.

4. Overharvesting a land (stripping it of nitrogen richness)

Quite frankly, take away the Nitrogen and plant life (and pretty much everything else) becomes difficult to support.