I have done this out in the run at my house with terrible mud- I dump every year 4 bags of play sand along my walkways and near the waterers to keep the chickens' feet and my feet from getting those terrible "mud shoes with suction."
I have read that if you mix clay and sand together it worsens soil drainage/makes concrete. But with just sand on top I would think that would help???
If every year you are having to add yet more sand.... where do you think the previous year's sand is disappearing to????? I'm sure some of it gets kicked around, but I imagine alot of it is getting worked down into that clay. Yes, if you could just put a layer of sand ON TOP OF the clay and have it stay there, everything would be hunkey-dorey.... but when it gets tromped on it is going to mix in.
I'm always for anything that results in less work, and all I know is that a bag of leaves is a lot lighter to haul than a bag of sand..... just sayin'.......
