Question

We need to use nitrogenous fertilisers even though our atmosphere contains 78% nitrogen because

• A. 78% Nitrogen is not enough for the amount of crops grown by human beings
• B. Plants cannot use nitrogen in the gaseous state
• C. Plants need some agent to mix the atmospheric nitrogen in the soil
• D. All of the above

Answer 1

The correct option is B Plants cannot use nitrogen in the gaseous state

Plants cannot use nitrogen in the gaseous state. N2 in the atmosphere has to be converted into ammonia, specifically the ammonium ion ($-N{H}_4^{+}$) and/or nitrates ($N{O}_3^{-}$) in the soil for plants to take it up through their roots.