Nitrogen
N & living beings
Needed for organic compounds
DNA
Proteins
...
Atmospheric N2 (78%) is unreachable for most
Only N-fixing bacteria can take it
Producers need is as NO3-, mostly
NO3- is the main way N enters the trophic chains
Consumers need it as organic compounds
Proteins
Aminoacids
...
The N cycle events
N-fixing bacteria in the legumes' root nodules: N2 in atm to NH4+ (usable by legume plants)
N-fixing bacteria in the soil: N2 in atm to NH4+ in soil
Nitrifying bacteria in soil: NH4+ to NO3-
Lightning & further on-soil reactions make NO3- from N2 in atm.
Producers absorb NO3- and make proteins & DNA
Consumers feed on producers taking their N-rich organic compounds
Detritivores feed on any biological detritus taking their N-rich organic compounds
Decomposers transform the N-rich organic compounds into NH4+
Denitrifying bacteria: NO3- in soil to N2 in atm.
NO3- can be washed by rainwater from soil into aquatic ecosystems
N & farmers
N can be added as manure
Rich in N-compounds that can be made into NH4+ by decomposers
Guano (excrement from seagulls, bats, seals) is very rich in NH4+ and NO3-
N can be added as manufactured fertilisers
Based on production of NH4+ by Haber-Bosch process