Where does all of the dirt come from for potting soil?

Question

If it is continually dug up from the ground , are there huge holes left in the ground someplace? Are there invisible Dirt Farms? It just seems strange because unlike other things that are harvested, soil does not reproduce itself. Or does it?

Answer 1

Much of potting soil can be reproduced organically because it is peat moss and compost.   Dirt can be dug out of the ground, but it can also be obtained as a byproduct of cleaning gravel and sand that must be washed before use in concrete and mortar.