"Bill who putters" wrote in message
http://www.ext.colostate.edu/Pubs/Garden/07235.html

Wood ash, an organic amendment, is high in both pH and salt. It can
magnify common Colorado soil problems and should not be used as a soil
amendment. Don't add sand to clay soil -- this creates a soil structure
similar to concrete.

I'm not in Colorado and didn't take on board that advice. I'm glad I
didn't. I've used both and had no problems.