I would suggest to get a shovel and till the dirt over time when it become hard and full of poo. My chickens loved when I till the dirt for fresh soil. They went bonkers to catch earth worm beneath when the turn soil became too fertile.
When they see me with the shovel, they know to come back...
When the coop smells, that certainly a good time to give it a good cleaning. You can use straw, pine shaving for bedding and nest material. They are not picky.