What can I spray (or sprinkle) on to the soil to deter rats?

I have planted out various seedlings in my "container garden" and have suffered from repeated visits from a rat who proceeds to dig up the seedlings and/or dig holes in the soil, thus making my hither-to successful gardening effort almost worthless.
I have tried various herbs, chipped hot peppers, rat bait - which I do not like to use because I have free-range dogs and chickens.
Any suggestions welcome! (By the way, I live in Barbados.)
  6 answers
Your comment...