I had issues a couple of years ago with slugs infesting my cruciferfous plants.
Here are a couple of things:
1) Salt will completely destroy the root systems of some of your plants, and I *highly* recommend against it, like, more vociferously than I can even tell you.
2) Slugs and snails are gastropods and have one thing in common: They cannot crawl over certain objects.
I had lost a whole crop of cauliflower to slugs before I found this remedy that is 100% completely natural.
Go to your local home improvement store and buy lava rock... the small stuff, the kind used for landscaping. Make little rings of lava rocks around your plants that you wish to keep free of slugs/snails. The snails and slugs *cannot* crawl across it. The microfine sharp edges of the lava rocks would shred them if they dared cross it.
Since trying this, I have not seen n'ary a single slug in ANY of my vegetables.