our dirt started turning to mud when we got a lot of rain and that is even with a covered run. so we switched to sand(3in) and never turned back. now the chickens lay around like they are in cancun on spring break. very easy to maintain and keep clean.
just a little note, something I didn't foresee (but makes sense)
When they see just a bit of bare dirt, it won't be long before it is a dusting hole! Don't forget the dust baths!