number of careful analyses made, in different seasons, of soils
which are already productive. The kind and quantity of
manures best adapted to renovate worn-out lands can be
shown only by their careful analysis and the noted results of
manures upon these lands. It is not enough to know that a
particular manure is adapted to a particular soil. The most
economical quantity, that which will give the greatest profit
from the smallest outlay, should be shown, both as to present
increase and future returns.

The above remarks lead us to the consideration of those
substances which are used as

MANURES.

By manures are to be understood those substances which
applied to soils, can either directly or indirectly supply plants
with nourishment. This is a general definition of manures.
It becomes special in reference to different soils, and they are
then in this relation, whatever substances can supply the ab-
sence or deficiency of those constituents of the soil which are
necessary to vegetation, either by supplying this absence or
deficiency of themselves, or which by their action on the soil,
can set free substances which may be present, but not in a
form capable of assimilation by the plant. The most perfect
knowledge, then, of the use of manures must be derived from
a knowledge of their nature and composition, and also of the
soils to which they are applied, and this is nothing more nor
less than the science of Chemistry.

In the application of all manures particular attention
should be paid to their equal and thorough distribution
through the soil, so that each plant may have its due supply-
In the selection of a manure, particular attention should be
given to its mechanical or physical state. Many failures of
manures are to be attributed not to the fact that the soil was
not deficient in their constituents, but that the manure used
was not in a fit state or condition when applied to the land
to be used by the plant.

An acre of land contains 6,272,640 square inches; a pound
av. 7,000 grs. It requires, then, about 900 pounds of any
manure to supply one grain to each square inch of soil. If,
then, in the application of 1,000 pounds of manure, say twen-
ty bushels of bone dust or any other manure, and there be
fragments of it weighing from one to two hundred grains,
as is often the case, there must be in some places nearly from
1 to 200 square inches entirely destitute of manure.

In order to give to the soil manure in the proportion of

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