But just what
do we mean by "soil"?
A
precise definition is elusive, for what we commonly call soil is
anything but a homogeneous entity. It is in fact an exceedingly
variable body with a wide range of attributes. Perhaps the best we
can do at the outset is to define soil as the fragmented outer
layer of the Earth's terrestrial surface in which the living roots
of plants can obtain anchorage and suste- nance, alongside a
thriving biotic community of microscopic and macroscopic
organisms.
The
recognizably different types of soil are legion, reflecting the
enormous heterogeneity of such determining factors as bedrock
composition, landscape (slope), climate, vegetation, and the
length of time the soil-forming process have been at work.
Specialists who call themselves pedologists are fond of endlessly
reclassifying soils into more and more types, to which they apply
strange-sounding names.
Daniel
Hillel: Out of the Earth, Univer- sity of California Press,
Berkeley, 1991. |