Plant roots take up nitrogen in the form of ammonium or nitrate ions. Atmospheric nitrogen is inert and must be converted to ammonia by nitrogen-fixing bacteria before it can be used by plants.
The function of nitrogen is an essential element and is utilized in plant cells to form proteins, which are critical for all plant growth.
Symptoms on broadleaf plants are leaves uniformly yellow-green (chlorosis), more pronounced in older leaves. the leaves become small and thin, with high color in the fall, dropping early; compound leaves with fewer leaflets. Shoots and internodes short and small in diameter and may be reddish or reddish brown. Flowers bloom heavily but may be delayed. The fruit set light; fruit small, highly-colored, maturing early.
The Symptoms on Conifers are the Needles become chlorotic, short, close together. Seedlings remain in primary needle stage with little or no branching. Poor needle retention by older plants. Lower crowns may be chlorotic while upper crowns remain green.