What should be added to garden soil to loosen it up?

Image by clattermonger
Night shots of the flower beds finally filled with soil. I couldn’t wait till the morning to take photos of them.

Question by fiestyredhead: What should be added to garden soil to loosen it up?
I need to loosen up the soil in a large garden box. I planted radishes, carrots and lettuce in it last year. They did terrible. The soil was too hard. What should be added to it when we turn the soil?

What do you think? Answer below!