One of the side benefits of using pallet grow boxes is that I get a half cubic yard of compost/soil out of one at the end of each crop. Sometimes I just add more organic material on top of the old stuff, then plant another crop. Sometimes I use the old compost/soil to inoculate the next pallet boxes. But other times I harvest it, sift it, and add it to my garden beds.
Oh yes, to comment upon the title of this post. Mother Nature created this soil. I just set things up.
I just harvested the yacon from this box, above, it's easy to see how the organic material has composted down half the height in the pallet box during the year long growing season.
The top layer is still very coarse, essentially acting as a mulch.
But further down in the pile, the organic material has decomposed some degree or other.
From this particular pallet grow box I'm harvesting the soil for some of the other garden beds. So I'm forking it out then sifting it to remove the biggest pieces of non-decomposed material. I prefer to sift directly into a wheelbarrow, making it easy for me to wheel the soil to whatever garden bed that needs it.
The sifted stuff looks, feels, and smells great. It's crumbly and moist. Not too super fine nor dusty.
And it's full of worms of all sizes. Love seeing those worms!
I've tried a variety of things to use for sifting the compost. My current favorite is an old plastic greenhouse tray. It's easy to hold, shake, and carry around with me. It's lightweight and does the job quite nicely. And it's simple.
The coarse material will go back into another pallet grow box or be used in filling in a hugel style pit. The coarse stuff is mostly tree twigs, fern stems, bark, and woody stuff that takes a long time to breakdown.