| Term | Definition |
| N2 | Nitrogen gas |
| NO3-1 | nitrate |
| NO2-1 | nitrite |
| NH3 | ammonia |
| NH4+1 | ammonium |
| N2O | nitrous oxide (gas) |
| nitrogen fixation | when N2 is converted to NO3-1, NH3 |
| de-nitrigication | bacteria in soil/water strip oxygen off NO3-1 and convert it back to N2 (atmospheric nitrogen) |
| leaching | surface run off dissolving the soil materials as a chemical weathering process and it transports the material downward |
| ammonification | decomposition releases NO3-1 to the soil |
| nitrification | NH3 in toxic to life so bacteria converts it to NO2-1 NO3-1 so its not toxic to us. |