| Term | Definition |
| plant and animal protein | blue and green algae in the world's seas and oceans, and fish...the globe pointing to water forms, and the dead fish |
| nitrogen fixing bacteria | what are the bacteria that "activate" the nitrogen in the soil called?...small plant with roots |
| nitrogen taken up by plant roots | nitrogen that the plant's take up... tree with roots |
| soil nitrate | nitrogenic soil... most things originate from it |
| plant and animal protein | made by flora and fauna and in flora and fauna...the sheep, eagle, and tree |
| dead organisms | the dead fish and dead things ... dead fish and dead cow with ribs showing |
| volcanic action | how volcanoes can activate nitrogen...volcano |
| atmospheric nitrogen | nitrogen in the atmosphere... in air and clouds |
| denitrifying bacteria in bogs | the bacteria that take up nitrogen in bogs...a bog with reeds |
| ammonium salts | salts in soil that help the nitrogen fix |
| lost to marine sediment | if dead organisms aren't able to be used for the soil, they're probably... |