Question

Why does the loosening of soil allow the roots to breathe easily?

Answer 1

Loosening of soil helps the air to fil up the space in them. And provide a much airy soil to the roots. This would help in easy diffusion of gases from the roots.

Answer 2

Roots breath:

To explain this state in a much clear way, let us consider the example of a street full of crowd where a person needs to pass through the crowd. It will be easier for the person to pass if the intensity of the crowd is less and very difficult if the intensity of the crowd is high.

That is what happens exactly with the air flow of roots too. The roots will breathe with an ease if the soil is loosened or it will be tough when the soil is tight.