Worms in woody and leafy mulch and in sand soil
I have very sandy soil, almost pure sand. There is a humus-enriched A-horizon (uppermost soil zone) a couple of inches thick, but basically it is medium grain-size sand.
Can earthworms handle sand, so long as there is something to eat at top?
I would like to use earthworms as part of the decomposition (along with natural bacteria and fungi) of thick mulch around fruit trees. I'd have coarsely ground tree debris (not good at first, I know) and grass clippings mainly as the mulch.
I could wait until the initial mulch had rotted some and could later easily feed them a bit supplementally. Will worms eat cottonsead meal, soya meal, alfalfa pellets or other animal feeds also used as fertilizer?
Final question, for now. If worms cannot travel readily through sand I would worry about dry periods when the mulch may dry to the bottom (the site is 25 miles away and without a well, not easy to water). What do you think about augering (3-inch diameter soil auger) down a foot or so in two or three places around each tree, beneath the mulch, and filling these deeper and thus moister "refugia" with something organic and highly suitable for worms. I'm thinking maybe peat moss or well-decomposed compost?
Thanks for any suggestions or information.