LOL thanks for this photo. I had guineas for a year before adding 5 chickens last Sept. Am wanting to add and plan for a dust bath as they all made lot of holes in their yard! I fenced in a wooded area that had 10" of loam and thought it would take years for them to scratch through. Hah. Little did I know- it was gone in 3 months! Anyway, the guineas dug out everything I put in my cement planters on my front porch (before I built them their own yard). No matter what I put in to 'fill' it up and discourage them they dug it out- rocks, pebbles, piles of mulch, thick plants...
This looks like ashes here. Is it just grey dirt? It was funny watching them standing to take their turns in the planter. I read here they like being in it together to will plan for a box in their coop.