Our quail are in a fixed aviary with bark chips on the floor. We had turf, but they destroyed it, and the bare earth wasn't a problem until we hit winter and it started turning to mud. Since we put the wood chips down we've had no problems. It allows them to supplement their diet with bugs they find, it keeps them amused, and produces good fertiliser. We have only got 6 quail in probably nearly 20 square foot of space though, so I definitely think that keeping quail on the ground means upping the space requirements per bird. Maybe to 3 square foot per bird or something. I'm pretty sure we could add maybe another 3 quail without them becoming cramped and poo becoming an issue.
Whatever you use on the floor, sand, earth, chips, you need to be able to turn it and scoop it out with a fork or something, that's the easiest way to keep it clean. I know you can get rubber chips for chicken runs, that should work for quail too, and then you just hose it down.