I allow one area in my back yard for digging. The dogs like to lay in the freshly dug holes when it gets hot out. Normally, once a week or so, I'll just rake the dirt back into the holes (there are three). Sometimes, we'll bring in extra dirt and cover them up.
If one of the more cheeky dogs decide to start digging in a non-dig zone, I'll put the poop that I've picked up into the hole and cover it with dirt. It will then remain a non-dig zone.
Hondo Von Dopplet L Bauernhof "Hondo"- GSD
Lilie's Tug McGraw "Tug" - Golden Retriever
Maggie - Mini Dachshund (Rescue)
Lonestar Pivo - Texas Blue Lacy
Ashe - Barn Cat
Katie / APHA