To avoid injury when you're putting an item down, proper technique involves:

You need to have proper ergonomics: make sure you don't put stress on your back and gently bend your knees and place the object on the ground

I am not properly educated on this, but I do know you are always meant to lift and set things down by using your legs to either heighten or lower yourself and the item. You would do this by squatting, grabbing the item, and returning to a standing position, the opposite goes for setting it back down. Do NOT use your back, so don't bend over to do this.