Question

Plant cannot use the nitrogen present in the soil directly.why?

Answer 1

Answer:

Plants do not use nitrogen directly from the air because nitrogen is noble gas and is unreactive, and cannot be used by greenplants to make protein. 

Answer 2

Answer:

Because atmospheric nitrogen is present as a free gas in the atmosphere, plants cannot use it directly. Instead, they can only absorb N2 from the soil in the form of nitrogen compounds like nitrates and nitrites, which are transformed by soil microorganisms.

Explanation:

To be used by plants, nitrogen must be converted via a process known as nitrogen fixation. Nitrogen fixation converts atmospheric nitrogen into forms (nitrites, nitrates) that plants can absorb via their root systems.

Therefore, nitrogen-fixing bacteria in the soil transform atmospheric nitrogen into a form that can be absorbed by plants.

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