Before trying to understand soil, stop thinking in such outmoded terms as "the dirt under your feet" or "common as dirt." Far from being common, soil is perhaps the most complex substance with which man must work to stay alive. Without it, there would be no plants -- his only source of the starches and sugars that are the fuels on which all living animals run.
The homeowner interested in gardening, unlike the farmer, does not make selection of soil his first concern, and few homes are purchased because they happen to have good soil under them. This vital substance for growing plants is not even considered until long after the purchase contract has been signed. It becomes of concern only when the owner becomes interested in gardening.
As a result, millions of prospective gardeners find themselves with stubborn clay or dry, porous sands rather than an ideal garden soil -- a mellow loam rich in organic matter. one British authority described that ideal soil as one so loose and friable that an arm could be thrust into it up to the elbow. Most American gardeners would be happy with a soil into which they could thrust a hand up to the wrist!