The dusting sites I have encountered usually have other sign with them: feathers, tracks, droppings, etc. They also are more of a depression in the soil. That being said, it is garden to tell from a photo.
When you do locate a dusting site, as far as set ups are concerned, that is something that would come after you have patterned the birds. Turkeys have a tendency to use dusting sites at certain times during the day, and if you can establish that pattern, it could be worth a set up. I will say that I have never done that. I have used the discovery of a dusting site more to establish that I have ,located an area that turkeys use regularly.
