I can't say enough about "paramagnetic" rock dust. I'm not much of a gardener but have a small patch that is basically an 8 foot tall "raised bed" on three sides that gets full sun all day and is right in the path of a sort of wind tunnel created by this hilly area, so it's dry as a bone and, I discovered a couple of years ago, full of earwigs! YUCK!! Those are creepy little things!
Anyway, it's only about 20' x 20' and rock dust made a world of difference. I also put it around the foundation along with some diatomaceous earth because I was a little concerned about where those evil-looking little buggers ran off to and didn't want them coming into the house. LOL! So far so good!