ACTER OF SOILS.

[What is the first office of the soil?

How does it hold water for the uses of the plant?

How does it obtain a part of its moisture?]

The mechanical character of the soil is well understood from preceding
remarks, and the learner knows that there are many offices to be
performed by the soil aside from the feeding of plants.

1. It admits the roots of plants, and holds them in their position.

2. By a sponge-like action, it holds water for the uses of the plant.

3. It absorbs moisture from the atmosphere to supply the demands of
plants.

[How may it obtain heat?

What is the use of the air circulating among its particles?

Could most soils be brought to the highest state of fertility?

What is the first thing to be done?

Should its color be darkened?]

4. It absorbs heat from the sun's rays to assist in the process of
growth.

5. It admits air to circulate among roots, and supply them with a part
of their food, while the oxygen of that air renders available the
minerals of the soil; and its carbonic acid, being absorbed by the water
in the soil, gives it the power of dissolving, and carrying into roots
more inorganic matter than would be contained in purer water.

6. It allows the excrementitious matter thrown out by roots to be
carried out of their reach.

All of these actions the soil must be capable of performing, before it
can be in its highest state of fertility. There are comparatively few
soils now in this condition, but there are also few which could not be
profitably rendered so, by a judicious application of the modes of
cultivation to be described in the following chapters.

The three great objects to be accomplished are:--

1. To adopt such a system of drainage as will cause all of the water of
rains to pass _through_ the soil, instead of evaporating from the
surface.

2. To pulverize the soil to a considerable depth.

3. To darken its color, and render it capable of absorbing atmospheric
fertilizers.

[Name some of the means used to secure these effects.

Why are under-drains superior to open drains?]

The means used to secure these effects are _under-draining, sub-soil and
surface-plowing, digging, applying muck, etc._

CHAPTER II.

UNDER-DRAINING.

The advantages of _under_-drains over _open_ drains are very great.

When open drains are used, much water passes into them immediately from
the surface, and carries with it fertilizing parts of t