Source. The chief source of nitrogen is the soil either in the form of nitrate, nitrite or ammonium salts. Some of the bacteria and heterocysts in blue green algae are also capable of fixing nitrogen of the atmosphere.

Regions. Nitrogen is required everywhere in plants, particularly in meristematic tissues.

Functions. Nitrogen is an essential constituent of proteins, nucleic acids, vitamins and many other organic molecules as chlorophyll. Nitrogen is also present in various hormones, coenzymes and ATP etc.

Deficiency symptoms

(i) Stunted growth.
(ii) Chlorosis.
(iii) Flowering reduced.
(iv) Apple and peach fruit highly coloured, developing slowly, small when mature.
(v) Decrease in protein contents.
(vi) Change in pigmentation.