ABSTRACT
Possibly the most widely known fact about the Earth is that two-thirds of its surface is covered by water, and one-third by land. From a human perspective, the “land” is covered by a variety of things. In the case of a city dweller, by tarmac, buildings, parks, concrete, and gardens; to a miner, by material that has to be removed in order to reach mineral deposits; and to a farmer, by a thin layer that if she is lucky will provide a living in the form of crops. It is this last perception that gives a clue about the important nature of soil.
