NITROGEN CYCLE

what bacteria is used in nitrogen fixation

• Azotobacter

• Rhizobium

what bacteria is used in nitrification

• Nitrosomonas

• Nitrobacter

what is used in decomposition

Saprotrophs/decomposers (e.g. bacteria/fungi)

what is used in ammonification

decomposers/bacteria

what bacteria is used in denitrification

denitrifying bacteria (pseudomonas)

where does nitrogen fixation happen?

• soil (azotobacter)

• root nodules (rhizobium)

• leguminous

where does nitrification happen?

soil

where does decomposition happen?

dead organisms in soil

where does ammonification happen?

dead organisms/faeces/urine/soil

where does denitrification happen?

soil, under anaerobic/waterlogged conditions

in nitrogen fixation, does oxidation or reduction of nitrogen occur?

reduction

in nitrification, does oxidation or reduction of nitrogen occur?

oxidation

in denitrification, does oxidation or reduction of nitrogen occur?

reduction

equation of nitrogen fixation

N₂ + H⁺ → NH₃

equation for nitrification

• Nitrosomonas: NH₄⁺ (found in fertilisers) / NH₃ → NO₂^-

• Nitrobacter: NO₂^- → NO₃^-

equation for decomposition

organic compound → inorganic compounds

e.g. plant/animal protein → ammonium (NH₄⁺) compound

equation for ammonification

nitrogen-containing molecules → ammonium (NH₄⁺) compound

equation for denitrification

NO₃^- → N₂