1. Nitrogen Cycle

2. What is Nitrogen? Nitrogen makes up about 78% of our atmosphere.
Nitrogen in the atmosphere it is mostly in the form of ______, which is a compound that plants and animals cannot use.
The process of converting nitrogen into compounds that can be used by plants and animals is called the ______________________. N2
Nitrogen Cycle

3. Why we care about nitrogen…
Nitrogen is an essential component of _____________________.The building blocks of life.
DNA, RNA and Proteins

4. How does atmospheric nitrogen (N2) get changed into a form that can be used by most living organisms?
Four
By traveling through one of the ________ processes in the Nitrogen Cycle!
(1) Nitrogen Fixation
(4) Denitrification
Nitrogen Cycle
(3) Nitrification
(2) Ammonification

5. Process 1: Nitrogen Fixation
___________________ is the process in which the N2 compound in the atmosphere breaks and combines with other compounds. The nitrogen is _________ when it combines with ______________ or _______________.
“fixed”
hydrogen
oxygen N N H N2 N H H
Nitrous Oxide (N2O)
Ammonia (NH3)

6. Three ways to “fix” Nitrogen
bacteria
Main process: Special ____________ convert the nitrogen gas (N2) to ammonia (NH3), which only ________ plants can use (peas, beans).
_________________ strikes convert N2 to N2O or NO3.
Industrial production. ____________ manipulation turns N2 into NH3 (Fertilizer)
some
Lightning
Chemical

7. Process 2: Ammonification
_____________________ - After all the living organisms have used the ___________________, decomposer bacteria convert the nitrogen to _______________.
Ammonification
organic nitrogen
ammonia H N H H
Ammonia
Bacteria
Organic Nitrogen (proteins)

8. Process 3: NitrificationH
_______________ is the process that converts ammonia (NH3) into nitrites (NO2) and nitrates (NO3) which ____ plants _______ use.
Note: Ammonia comes from ______ nitrogen fixation and ammonification
How is it done?
_____________________
Nitrification N H H
most
can
Both O O N O N
Bacteria! O O

9. Process 4: Denitrification
_______________: Process in which nitrogen compounds _____________________ into atmospheric nitrogen (N2 or N2O).
The main process is performed by _____________________ in the soil. It can also happen by _____________ fossil fuels.
Denitrification
convert back
bacteria
burning N2
NO3
N2O

10. N2 N2O NO3 NH3 (1) Nitrogen Fixation (4) Denitrification
Nitrogen Cycle
(2) Ammonification
NO3
NH3
(3) Nitrification
Ammonia is converted to nitrites and nitrates.
Nitrates in Soil
Organic nitrogen is converted to ammonia.

11. decomposition by bacteria & fungi
Nitrogen in
the air
nitrogen fixing plant
eg pea, clover
animal protein
plant made
protein
dead plants & animals
urine & feces
denitrifying
bacteria
root nodules
(containing nitrogen
fixing bacteria)
decomposition by bacteria & fungi
nitrates absorbed
nitrates
ammonia
bacteria
nitrites
bacteria
(nitrifying bacteria)

12. Human Impact Combustion Commercial Fertilizers mineral deposits
___________________, releases toxic nitrogen compounds into the atmosphere.
____________________________ release nitrous oxide into the atmosphere and introduce excess nitrogen into the environment.
Remove nitrogen from the soil when we mine it for nitrogen rich __________________________.
Discharge of ___________________________ releases excess nitrogen into the water ecosystems which disrupts the aquatic balance and kills fish.
Commercial Fertilizers
mineral deposits
municipal sewage

13. Commercial Fertilizers#1
Are the ______ contributor of new nitrogen in the nitrogen cycle.
Added because nitrogen is a ________________ for plant growth.
Problems: hard to apply fertilizer and keep it in one area. Runoff, evaporation, etc.. So farmers apply about ___________________ as they need.
Extra nitrogen disrupts the ________________.
limiting factor
twice as much
food chain

14. Exit Ticket What are the four main processes of the nitrogen cycle?
What is it called when bacteria convert nitrogen into ammonia?
What organism is required for every step of the nitrogen cycle?