Question

How does Nitrogen gets fixed to the soil due to lightning?

Answer 1

by nitrogen fixation nitrogen gets fixed due to lightning.

Answer 2

Lightning has a tremendous energy in it.
The nitrogen molecules breaks into smaller atoms and combine with air especially O₂ (oxygen) to form respective oxides mainly nitrogen oxide.
Rain dissolves these molecules, thus bringing them on earth.
And this is how nitrogen gets fixed in the soil due to lightning.