I have a neighbor, who has a neglected yard, and slugs that migrate under, through and around a wooden fence. I have been using Epsom Salts,(Magnesium Sulfate) as a broadcast of crystals, as a deterrent, and it is working well. I do not think this kills them, because there are no carcasses to inspect and remove (which I do at night). It is definitely been a deterrent, as the last two weeks, no more. I am not recommending this for alpines, as I am not sure what it would do with PH or could counter some of the nitrogen uptake.
If anyone knows if this could be used on alpines, please let me know. Thank you.
Cecile