the nitrogen cycle

What are saprobionts

these are bacteria that break down dead or decaying organic matter. They do this by extracellular digestion. A by-product of this is ammonium ions going into the soil. Meaning they are important in the ammonification stage of the nitrogen cycle

reactions in the nitrogen cycle

nitrification

ammonification

denitrification

nitrogen fixation

Nitrogen fixation

occurs when nitrogen in the air reacts with hydrogen to form ammonium by nitrogen fixing bacteria such as rhizobium

N2 + 3H2 makes 2NH3

ammonification

organic matter is decomposed by saprobionts to release ammonium into the soil this occurs under anaerobic conditions

NO2-/NO3- decomposes into NH4+

plants will then use the nitrogen in the ammonium to form proteins and nucleic acids

nitrification

ammonium is first converted into nitrites and then nitrates first by nitrosomas and then by Nitrobacter

NH4+ — N02- —— N03-

the nitrate can then be reabsorbed back into the pants by the root

denitrification

where the nitrates are converted into atmospheric nitrogen by pseudomonas

N03- —— N2