Eli5 why plants which need nitrogen from the ground do not take it from the air which is 70% Nitrogen

Question

Eli5 why plants which need nitrogen from the ground do not take it from the air which is 70% Nitrogen

In: 308

Answer 1

Most of the nitrogen in the air is diatomic, pairs of nitrogen atoms bound together. That’s a very strong bond, which is difficult to break apart with the kind of energy plants have available to them, so the nitrogen they consume mostly comes from compounds which contain nitrogen and are held together by much weaker bonds.