1. Nitrogen Cycle

2. Root Words Node Knot Nodules Re Again Recycle Cycl Circle
Nitrogen Cycle
Atmo
Vapor
Atmosphere
Troph
Nourishment
Trophic level

4. What is Nitrogen? Necessary building block in living things
Air = 78% Nitrogen gas

5. Why do we need Nitrogen?
All living organisms need nitrogen in order to build proteins and build DNA
Most animals get the nitrogen they need by eating plants.

6. Nitrogen Cycle
The process by which nitrogen is removed, consumed and released back into the atmosphere

7. Nitrogen Fixation
The process of changing free nitrogen gas (from the air) into a usable form of nitrogen
Performed by bacteria

9. What kind of plants?
Bacteria live in the roots of plants called legumes
Example: Clover, beans, peas, alfalfa, and peanuts

10. Farmers
Farmers will often plant alfalfa in their fields so that their soil will be rich in nitrogen
Bacteria in the roots “fix” the nitrogen so it can be used.

11. Now What?
Once bacteria in the roots of plants have “fixed” the nitrogen, the nitrogen can be used by organisms to build proteins and other complex substances.
Plants absorb the nitrogen
Animals eat the plants

12. Recycling
Decomposers break down these complex compounds in animal wastes and in the bodies of dead organisms.
Nitrogen is now returned to the soil
Nitrogen can be recycled over and over again
Bacteria can also return “free” nitrogen back to the air.

13. Human Influence Nitrogen enhanced fertilizer Chemical fertilizers
Cow manure has lots of nitrogen!
Pollution

14. Question…
Nitrogen fertilizer is often added to soil to increase the growth of crops. Which of these ecosystems would most likely be harmed by the use of nitrogen fertilizer?
Forest
Pond
Park
Meadow

15. Answer
In this example, water ecosystems would be harmed the most from fertilizer runoff, making Choice B, a pond, the correct answer.
Fertilizer would increase the growth of water plants and algae, thus reducing the resources for some living organisms in the pond.

17. Foldable 8

18. 1. Nitrogen is introduced into the soil by precipitation (rain, lightning).  2. Nitrates don’t only come from Nitrogen in the air. They can also be obtained by the conversion of ammonia, commonly used in fertilizers by nitrifying bacteria in the soil. Some root nodules can also convert nitrogen in the soil into nitrates. 3. Plants build up proteins using nitrates absorbed from the soil. 4. When animals like cows, eat these plants, they, in turn, use it to build animal protein.  When these animals (cows) poop, pee or die, the urea, excreta or carcass are broken down by decomposers and the nitrogen is re-introduced into the soil in the form of ammonia. 7. Nitrates in the soil can also be broken down by denitrifying bacteria (in specific conditions) and sent into the air as nitrogen. This process can help make the soil infertile because it will lack the nitrates needed for plant use.
8. Nitrogen is absorbed into the atmosphere. The cycle starts over again.