a bit different up in Scotland, I think. Usually it is the referee (after they've inspected the pitch) that decides - if it is a local council park then it can be them that will call it off on safety grounds. But mostly it is down to the referee.Down to competition rules, not all will be the same. It can also sometimes come down to more than the pitch, for example when there is a severe weather warning leagues often allow clubs to self-postpone games without needing a referee or the ground authority saying it wasn't playable.