I've never even heard of cursed dirt, but I would assume with a name like that it would be used for something malevolent or non-beneficial.
I know graveyard dirt is often used in curses and hexes(from what I've read it is placed in poppets along with several other items, for this purpose), perhaps this dirt has the same purpose. If so I would advise against using it.
Sorry I can't be of more help with this though.
Blessed Be and With Respect,