Stop!

What is a cycle?

Discus

s

A series of events that repeat, with no beginning

or end.

Stop!

Why is Nitrogen

important to us?

Nitrogen makes up the

proteins in our bodies.

What is What is nitrogen?nitrogen?

Nitrogen is an element.

78% of the 78% of the earth’s earth’s

atmosphereatmosphere

78% of the 78% of the earth’s earth’s

atmosphereatmosphere

rare in soilrare in soilrare in soilrare in soil

major major componentcomponent

of Dof DNNAA

major major componentcomponent

of Dof DNNAA

N

colorless, colorless, odorless gasodorless gascolorless, colorless,

odorless gasodorless gas

Nitrogen must be converted -fixed - into useable compounds.

Although nitrogen is abundant in the atmosphere,

N2

N2 N2

N2 N2

N2

N2

N2N2

N2

N2

N2

N2

organisms can not use N2 in its gas state.

Where doesWhere doesnitrogennitrogen

come from?come from?

Nitrogen Fixation is the process that causes the nitrogen molecules found in the atmosphere to break apart so they

can combine with other atoms.

There are 2 kinds of bacteria that move nitrogen through the nitrogen cycle.

bacteria that bacteria that change nitrogen change nitrogen from a gas to a from a gas to a

solid.solid.

bacteria that bacteria that change nitrogen change nitrogen from a gas to a from a gas to a

solid.solid.

bacteria that bacteria that changes it from changes it from a solid to a gas.a solid to a gas.

bacteria that bacteria that changes it from changes it from a solid to a gas.a solid to a gas.

Some bacteria live in the soil and others live in the roots of

plants

nitratesnitrates

Bacteria convert nitrogen gas into nitrate solids, NO3.

Plants can absorb nitrate solids through their roots.

Energy from lightning during a thunderstorm converts N2 (gas) into nitrate

solids, NO3.

N2

N2 N2

N2 N2

N2

N2

N2N2

N2

N2

N2

N2

nitratesnitratesnitrates

nitratesnitratesnitrates

N2

N2

N2

N2

N2

nitratesnitrates

Other bacteria in the soil break down nitrate solids (NO3) back into N2 (gas).

N2

N2 N2

N2 N2

N2

N2

N2N2

N2

N2

N2

N2 N2

N2

N2

N2

N2

N2

N2

N2

Denitrification is the process in which bacteria in the soil convert nitrates into

nitrogen gas.

nitratesnitrates

N2

N2 N2

N2 N2

N2

N2

N2N2

N2

N2

N2

N2

nitratesnitratesnitrates

nitratesnitratesnitrates

N2

N2

N2

N2

N2

N2

N2

N2

Discuss

So, what would happen if So, what would happen if the bacteria or lighteningthe bacteria or lightening were removed from the were removed from the

nitrogennitrogen cycle?cycle?

ammonia

nitratesnitrates

waste decomposers

Animal wastes decompose, adding nitrogen in the form of ammonia (NH4)

back to the soil.

Plants and animals contain nitrogen compounds. Decomposers break down

biotic organisms and release the nitrogen compound in the form of

ammonia (NH4)

N2

N2 N2

N2 N2

N2

N2

N2N2

N2

N2

N2

N2 N2

N2

N2

N2

Ammonification is the process in which decomposers (bacteria and fungi) convert

amino acids from dead animals and wastes into ammonium.

ammonia

nitratesnitrates

waste decomposers

Other bacteria convert ammonia back into nitrate solids.

N2

N2 N2

N2 N2

N2

N2

N2N2

N2

N2

N2

N2 N2

N2

N2

N2

Nitrification is the process in which bacteria convert ammonium into nitrates.

ammonia

nitratesnitrates

waste decomposers

N2

N2 N2

N2 N2

N2

N2

N2N2

N2

N2

N2

N2 N2

N2

N2

N2

Discuss

Explain what causes Explain what causes the the

nitrogen cycle to nitrogen cycle to continually change.continually change.