Almost all of the vegetables we find on grocerystore shelves are produced either directly or
indirectly in open-field soil. However, soil itself isn't
necessary for plant growth - only some of its
constituents.
Field soil serves two basic purposes: it acts as a
reservoir to retain nutrients and water, and it
provides physical support for the plant through its
root system. Artificial means can also provide these
important requirements for plant growth with equal
(and sometimes better) growth and yield results
compared to field soil, although at substantially
greater expense. Well-drained, pathogen-free field
soil of uniform texture is the least-expensive medium
for plant growth, but soil doesn't always occur in this
perfect package. Some soils are poorly textured or
shallow, and provide an unsatisfactory root
environment because of limited aeration and slow
drainage. Pathogenic organisms are a common
problem in field soils. When adverse conditions are
found in soil and reclamation is impractical, some
form of soilless culture may be justified. This guide
describes the materials used in soilless culture and
discusses management practices in various soilless
systems.