Nitrogen Cycle

1. In the water, these help convert nitrogen gas into ammonia.
4. Helps return nutrients to the soil without using fertilizers.
7. Humans add this to the soil to increase the amount of nitrogen in the soil.
8. Circulates nitrogen between the atmosphere, soil, bacteria, and plants in the ecosystem.
9. These fix nitrogen in the soil around the roots of plants.
10. Happens during bad weather to split nitrogen molecules in the air.
11. This element makes up 78% of the atmosphere.
12. When plants and animals die, their nitrogen compounds are broken down into this.
13. Release nitrogen into the soil through their waste.

2. 80% of this consists of nitrogen, making it the largest reservoir of nitrogen on Earth.
3. During this process, bacteria and fungi break down wastes and remains of organisms into ammonia.
5. During this process bacteria convert nitrogen in the soil and release it back into the atmosphere.
6. Nitrogen is the building block of these, a component of protein in all living things.
7. fuels Humans burn this to help fix nitrogen.
10. This crop is able to fix nitrogen from the atmosphere and into the soil.