st?]

The soil is not to be regarded as a mysterious mass of dirt, whereon
crops are produced by a mysterious process. Well ascertained scientific
knowledge has proved beyond question that all soils, whether in America
or Asia, whether in Maine or California, have certain fixed properties,
which render them fertile or barren, and the science of agriculture is
able to point out these characteristics in all cases, so that we can
ascertain from a scientific investigation what would be the chances for
success in cultivating any soil which we examine.

The soil is a great chemical compound, and its chemical character is
ascertained (as in the case of plants) by analyzing it, or taking it
apart.

We first learn that fertile soils contain both organic and inorganic
matter; but, unlike the plant, they usually possess much more of the
latter than of the former.

In the plant, the organic matter constitutes the most considerable
portion of the whole. In the soil, on the contrary, it usually exists in
very small quantities, while the inorganic portions constitute nearly
the whole bulk.

[Can the required proportion be definitely indicated?

From what source is the inorganic part of soils derived?

Do all soils decompose with equal facility?

How does frost affect rocks?

Does it affect soils in the same way?]

The organic part of soils consists of the same materials that constitute
the organic part of the plants, and it is in reality decayed vegetable
and animal matter. It is not necessary that this organic part of the
soil should form any particular proportion of the whole, and indeed we
find it varying from one and a half to fifty, and sometimes, in peaty
soils, to over seventy per cent. All fertile soils contain some organic
matter, although it seems to make but little difference in fertility,
whether it be ten or fifty per cent.

The inorganic part of soils is derived from the crumbling of rocks. Some
rocks (such as the slates in Central New York) decompose, and crumble
rapidly on being exposed to the weather; while granite, marble, and
other rocks will last for a long time without perceptible change. The
_causes_ of this crumbling are various, and are not unimportant to the
agriculturist; as by the same processes by which his soil was formed, he
can increase its depth, or otherwise improve it. This being the case, we
will in a few words explain some of the principal pulverizing agents.

1. The action of frost.