The Nitrogen Cycle:
v The transfer of nitrogen from the atmosphere to the soil, to living organisms, and back into the atmosphere is called the Nitrogen cycle.
· Living things cannot exist without nitrogen. It is a basic element of all living things. (It is essential for cells & DNA)
· Nitrogen is found in both living and nonliving things.
· Atoms of nitrogen don’t just stay in one place. They move slowly between living things, dead things, the air, soil, and water.
· Most of the nitrogen on Earth is in the atmosphere. But, most organisms cannot use nitrogen directly from the air.
· The molecules of nitrogen can become usable to living things when they are broken apart during lightening strikes, volcanic activity, fires, or certain bacteria.
-Plants absorb nitrogen compounds through their roots.
-Animals obtain nitrogen by eating plants or other animals.
-When organisms die, the nitrogen in their bodies returns to the soil or atmosphere.
The Nitrogen Cycle:
The transfer of ______from the atmosphere to the soil, to ______, and back into the atmosphere is called the nitrogen cycle.
· Nitrogen is important to all ______things.
· Nitrogen is a essential for ______and ______.
· Most of the nitrogen is found in the ______, but
organisms cannot use nitrogen directly from the air.
· Nitrogen does not always stay in ______place. They move between ______things, ______things, the ______, and water.
Plants absorb these nitrogen compounds through their roots.
Animals obtain nitrogen by eating plants or other animals.
When organisms die, the nitrogen in their bodies returns to the soil or atmosphere.
Humans affect the nitrogen cycle.
Farming depletes the nitrogen compounds in the soil.
If the nitrogen compounds are not replaced, the soil will become infertile.
Nitrogen is a limiting factor for plant growth.
Have you ever noticed that adding fertilizers to the soil can make your plants grow greener, fuller, and healthier? Fertilizers contain nitrogen compounds.
Composts (Remember back to our discussion on compost piles) and animal manure contain needed nitrogen compounds.
Farmers also plant nitrogen – fixing crops.
Nitrogen – fixing bacteria live on the or in the roots of some plants (such as peas and beans)
The molecules of nitrogen in the atmosphere can become usable for living things when:
1. They are broken apart during lightning strikes or fires
2. Dead and decaying matter gets broken down by bacteria (decomposer) and then is available in the soil to living organisms
3. When certain types of bacteria that live on plant roots supply nitrogen compounds to the plant