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 is primarily available to plants in the form of nitrate ions (NO3-) in the soil. While N2 is abundant in the atmosphere, it cannot be directly utilized by most plants. Nitrite ions (NO2-) can also be present in soil, but they are often toxic to plants in high concentrations. Urine from animals can contain significant amounts of nitrogen, but it must first decompose and be converted into nitrate ions before it can be taken up by plants. Lastly, while decomposing plant and animal proteins can release nitrogen in the form of amino acids, this nitrogen must also be further broken down into nitrate ions by soil bacteria before it can be used by plants.

Nitrogen Is Available to Plants Only in the Form of