First off, you need worms and not your typical earthworms.

His research on plants was published in a series of books, and in his final book, he examined earthworms and their effect on soil.

And there are a few other land dwellers that can make light some insects, earthworms, fungi but in general, on land, it's really rare.

And the species in the soil go to work basically chewing through those roots, decomposing them the earthworms, the fungi, the bacteria and the result is new soil.