It would be a good idea, since slugs and snails require their slime to move around then anything to dry them upand impede there movement would be good and a little potash won't harm the soil, coffee grounds are another good choice.
Sawdust is good but only after it as sat for a year, if it is fresh it is too acidic, and will harm any plants it is put on. I found this out the hard way.
The only plants that don't like wood ash are acid loving plant. wood ash has been used for centuries has a fertilizer. I put wood ash in my garden every year, it acts as a liming agent and adds nutrients into the soil.
