The terms "manure" and "fertilizer" are used
somewhat ambiguously and interchangeably. Using the former term in a
broad sense--as meaning any substance containing available plant food
applied to the soil, we may say that manure is of two kinds: organic,
such as stable manure, or decayed vegetable matter; and inorganic, such
as potash salts, phosphatic rock and commercial mixed fertilizers. In a
general way the term "fertilizer" applies to these inorganic manures,
and I shall use it in this sense through the following text.

Between the organic manures, or "natural" manures as they are often
called, and fertilizers there is a very important difference which
should never be lost sight of. In theory, and as a chemical fact too, a
bag of fertilizer may contain twice the available plant food of a ton
of well rotted manure; but out of a hundred practical gardeners ninety-
nine--and probably one more--would prefer the manure. There is a reason
why--two reasons, even if not one of the hundred gardeners could give
them to you. First, natural manures have a decided physical effect upon
most soils (altogether aside from the plant food they contain); and
second, plants seem to have a preference as to the _form_ in which
their food elements are served to them. Fertilizers, on the other hand,
are valuable only for the plant food they contain, and sometimes have a
bad effect upon the physical condition of the soil.

When it comes right down to the practical question of what to put on
your garden patch to grow big crops, nothing has yet been discovered
that is better than the old reliable stand-by--well rotted, thoroughly
fined stable or barnyard manure. Heed those adjectives! We have already
seen that plant food which is not available might as well be, for our
immediate purposes, at the North Pole. The plant food in "green" or