I have thousands of snails and slugs in my garden every year. I have tried everything to get rid of them.
Ducks are the best solution. They are the sentinels watching over your plants.
Next best thing is snail killing bait. It works great but it's expensive and melts in the rain after a few days.
Diatomaceous earth only works when it's dry, so you would need to make some kind of tunnel full of the stuff that the snails would climb into? Also it kills any insects that crawl over which isn't great for your garden's biodiversity.
Next best thing is sacrificial plants. Small tender broad leaves placed low and all around the plants you want to protect. They will devour these first and give you time to do a daily round-up in the morning or evening.
Next, the snail electric fence. Get an outdoor solar powered lamp, some copper tape, and plywood. Bury the plywood around your bed (if you don't have a raised bed). Attach the copper tape in two thin strips very close to each other around the perimeter. Hook each line up to one of the leads for the solar lamp. When a slug or snail crosses both copper tape lines, they will get a small zap and run away. Works great but it's finicky to set up and the smallest snails and slugs can get in between the lines and not be zapped.