plants are unable to use atmospheric --------------

Answer:

Nitrogen

plant can't use atmospheric nitrogen so becteria present is soil fir nitrogen in soil so they can be used by plant.

Answer:

plants are unable to use atmospheric nitrogen.

Explanation:

as we know that plants require so much nitrogen because it is necessary for plants to absorb nitrogen as it is the basic compound for protein of plants.

also for DNA and RNA(the genetic material) .  

plants obtain the nitrogen from the nitrogen cycle.

Plants simply absorb the nitrogen from soil through their roots as amino acids or ammonium ions.