Explain the nitrogen cycle with suitable flow chart.

Explanation

`N_2` is an important constituent of protoplasm is an important constituent of protoplasm, amino acids. proteins. nucleic acid, enzymes, etc. Major reservoir of N2 is atmosphere (78%). it cycle is a complex and perfect cycle and is as follows-
(a) Nitrogen fixation (b) Ammonification (c ) Nitrification (d) Denitrification
(a) Nitrogen fixation. It is of following types-
(i) Atmospheric or Abiological `N_2` fixation by photochemical and electrochemical reactions
`N_2+O_2 to 2NO`
`2NO+O_2 to 2NO_2`
`2NO_2+H_2O to HNO_2+HNO_3`
In the tropics large quantity of `N_2` is converted into `NH_3` due to thunder storms and lightening.
(ii) Biological `N_2` fixation- It is very efficient done by five living bacteria or symbiotic `N_2` fixing bacteria.
Symbiotic `N_2` fixing bacteria Rhizobium leguminoscarum in root nodules of legumes. Frankia in root nodules of Alnux. cyanobacteria like Nostic and Anabaena in roots of eyes.
Free living `N_2` fixing bacteria Azatobacter, Beijerinkia, Azospirillium
(iii) Industrial `N_2` fixation
`2N_2+3H_2 to 2NH_2` Synthesis by Haber process at high temperature of `400^@C` ad pressure of around 200 atmosphere.
(b) Ammonification. IT involves the decomposition of proteins of dead animals and plants into ammonia by ammonifying bacteria also called putrefying bacteria or bacteria of decay e.g Bacillus ramous B, vulgarix
Proteins `to` Amino acids `to` Ammonia
(c) Nitrification . It involved the oxidation of ammonia to nitrates through nitrites in the presence of nitrifying bacteria
`2NH_3 +3O_2 underset(Nitro oc cus)overset(Nitrosomonas) to 2NO_2^(-) +2H^+ +2H_2O`
`2NO_2^(-) +O_2 underset(Nitrocystis) to overset(Nitrobacter) 2NO_3^(-) +`energy
(d) Denitrification In this nitrates , nitries are allowed are reduced to `N_2` is presence of denitrifying bacteria e.g Thiobacillus denitrificans, Bacillus subtills
`NO_3^(-) to NO_2^(-)` Nitrite `to` NO (Nitrous oxide)
(Nitrate)
`NO to N_2O` (Nitric oxide) `to` N_2 (Nitrogen)