Nitrogen cycle

Ionisation

lightning or meteor trails provide the energy for atmospheric nitrogen and oxygen to react and produce oxides of nitrogen in the soil

Denitrification

the chemical reduction of nitrates in soil to nitrogen and NOx, by denitrifying bacteria in the soil, reduces soil fertility.

Ammonification

the amino groups in proteins are released as ammonium ions by the action of bacteria, fungi and detritivores as they decompose dead organic matter.

Nitrogen fixation

a process where free nitrogen combines chemically with other elements to form more reactive nitrogen compounds such as ammonia, nitrates or nitrites.

Nitrification

the oxidation of ammonium to nitrites, then nitrates, by nitrifying bacteria