Nitrogen is available to plants only in the form of
A) N₂ in the atmosphere.
B) nitrite ions in the soil.
C) uric acid from animal excretions.
D) amino acids from decomposing plant and animal proteins.
E) nitrate ions in the soil.

Question

Quizplus · Accepted Answer

Nitrogen can only be taken up by plants in the form of nitrate ions in the soil. Nitrogen gas in the atmosphere must be "fixed" by bacteria or lightning to make it available in the form of nitrate. Nitrite ions can be toxic to plants at high levels, and uric acid is not readily available for plant uptake. While decomposing plant and animal proteins contain nitrogen, it needs to be broken down into nitrate by bacteria before plants can use it.

Nitrogen Is Available to Plants Only in the Form of