r may make, will inform us of its
deficiencies in _mechanical_ character, and we may at once resort to the
proper means to secure fertility. In some instances the soil may contain
every thing that is required, but not in the necessary condition. For
instance, in some parts of Massachusetts, there are nearly _barren_
soils which show by analysis precisely the same chemical composition as
the soil of the Miami valley of Ohio, one of the most _fertile_ in the
world. The cause of this great difference in their agricultural
capabilities, is that the Miami soil has its particles finely
pulverized; while in the Massachusetts soil the ingredients are combined
within particles (such as pebbles, etc.), where they are out of the
reach of roots.

[Why do soils of the same degree of fineness sometimes differ
in fertility?

Can soils always be rendered fertile with profit?

Can we determine the cost before commencing the work?

What must be done before a soil can be cultivated understandingly?

What must be done to keep up the quality of the soil?]

In other cases, we find two soils, which are equally well pulverized,
and which appear to be of the same character, having very different
power to support crops. Chemical analysis will show in these instances a
difference of composition.

All of these differences may be overcome by the use of the proper means.
Sometimes it could be done at an expense which would be justified by the
result; and, at others, it might require too large an outlay to be
profitable. It becomes a question of economy, not of ability, and
science is able to estimate the cost.

Soil cannot be cultivated understandingly until it has been subjected to
such an examination as will tell us exactly what is necessary to render
it fertile. Even after fertility is perfectly restored it requires
thought and care to maintain it. The ingredients of the soil must be
returned in the form of manures as largely as they are removed by the
crop, or the supply will eventually become too small for the purposes of
vegetation.

FOOTNOTES:

[T] It is due to our country, as well as to Prof. Mapes and others, who
long ago explained this absorptive power of clay and carbon, to say that
the subject was perfectly understood and practically applied in America
a number of years before Prof. Way published the discovery in England as
original.

SECTION THIRD.

MANURES.

CHAPTER I.

CHARACTER AND VARIETIES OF MANURES