Nitrogen

Dinitrogen Gas (N2)

triple bond, inert, and not directly usable by plants

Haber-Bosch Process

an industrial process for producing ammonia from nitrogen and hydrogen

Biological Nitrogen Fixation (BNF)

Biochemical process done by Diazotrophs that fixes dinitrogen gas into ammonia

Nitrogen in the soil is mostly organic or inorganic?

Organic

Plants must turn _______ into _______ in order to Absorb N

organic N into mineral N

Ammoniafication

Conversion of organic amine groups into ammonium

Nitrification

ammonium is oxidized into nitrite through Nitrosomonas then the nitrite is oxidized into nitrate through Nitrobacter

Mineralization of N

Transformation of large organic N molecules into amines, then into ammonium, and sometimes continues to produce nitrate

Nitrogen Immobilization

conversion of Mineral N (ammonium and nitrate) into organic N by soil microorganism uptake

Denitrification

Conversion of nitrates into nitrogen gas (N2, N2O, NO) by anaerobic bacteria in anaerobic environments. Produces green house gas nitrous oxide

Ammonia volatilization

-Loss of nitrogen in the form of ammonia

-pH dependent, in lower pH this process is reduced

Main contact mechanism for Nitrogen to be uptook by plants

Mass flow

Main absorption pathway

the symplastic route through the plasmodesmata

Eutrophication

when excess nitrogen flows into groundwater and into rivers, lakes and seas. Causes excessive growth of algae and cyanobacteria

N assimilation if absorbed as Nitrate

nitrate reduction into ammonium then ammonium is assimilated into amino acids; occurs mainly in leaves

N assimilation if absorbed as ammonium

direct ammonium assimilation into amino acids; occurs mainly in roots

Nitrate reductase

reduces nitrate to nitrite

Nitrite Reductase

reduces nitrite to ammonium form

Ammonium assimilation

assimilation of ammonium into organic compounds; GS-GOGAT pathway

Enzymes glutamine synthetase (GS)

catalyzes the condensation of an ammonium ion (NH₄⁺) with glutamate to form glutamine.

Enzymes glutamate synthase (GOGAT)

turns glutamine into 2 molecules of glutamate

Symptoms of nitrogen deficiency

Generalized yellowing starting with older leaves, reduced plant growth, and low production

Symptoms of nitrogen excess

excessive vegetative growth, stems cells enlarge causing lodging, and delay in maturity and flower production