Nutrient cycle

1. eight percent our atmosphere is made up of how much with nitrogen gas
4. what classification had volcanic eruptions, rock formations, and plate tectonics
5. humans add what through fertilizer
6. it is an essential nutrient for life as it makes up important chemicals
8. what classification is activities preformed by living organisms
9. some of the phosphorus in soils can be washed away in
10. nutrient nutrient whose supply limits productivity
12. animals and plants cannot directly use all the nitrogen found in our what
14. animals use oxygen in the process of what to make more CO2
16. what is used to help replace for plants
18. with ample amount of sun the limit to productivity would be what
19. in the past huge deposits of carbon were stored as dead plants and animals

2. what is another natural recourse for CO2
3. bacteria in the soil can break down ammonia into the gaseous form of nitrogen
5. chemical substances that an organism needs to sustain life
7. what is within each of the cycles
11. higher organisms use nitrogen to make what
13. too much CO2 in the atmosphere may be responsible for what
15. another source of phosphorus in water comes from man made what
17. is the main regulator of CO2 in the atmosphere because CO2 dissolves easily in it