258 
The Offices of Soils—Soil affords mechanical 
support to plants growing in it. Plants can 
neither stand of themselves on the surface of the 
ground, nor move from place to place in quest of 
their daily food, but require to remain long on 
one spot, and there to send their roots down- 
ward, and to spread their radicles beneath the 
surface. And the soil is exactly adapted to their 
wants. Being a finely divided solid, it permits their 
roots and radicles to push through it in all direc- 
tions; and being, at the same time, closely aggre- 
gated, it holds them sufficiently fast to prevent 
them from falling by their own gravity, and from 
being torn up or overwhelmed by ordinary winds ; 
and being also permeated by air and moisture, it 
maintains them in the precise position and cir- 
cumstances which are suitable to their constant 
feeding. The different kinds of soil, too, have 
exactly the varieties of texture which are best 
adapted to the form and habits and wants of the 
particular species of plants which naturally in- 
habit them. 
Soil supplies part of the inorganic food of 
plants, and serves as a ready vehicle for the re- 
ception of other parts. Its stores of silica, alu- 
mina, and lime afford supplies of the nutrimental 
principles derivable from them, which are in many 
instances inexhaustible,—and in most of at least 
long continuance ; and its mechanical condition 
and capacities receive in the readiest manner all 
sorts of natural and artificial additions of other 
nutrimental substances, and store them up in 
ways which both make them most facilely acces- 
sible to the roots of plants, and most effectually 
prevent their waste or dissipation by interfering 
causes. 
Soil acts as the stomach of plants, or as the 
laboratory in which their food is prepared for 
absorption by their spongioles. The substances 
which yield this food, whether as they exist 
naturally in virgin soils or as they are artificially 
added to soils which have been long in cultivation, 
require in some instances to be dissolved, and in 
most to be also decomposed and recombined before 
they assume the form of food; and at the same 
time, either the substances themselves or the 
principles which result from them must be so 
diffused, economized, and progressively reduced 
as to afford a continuous contribution of nour- 
ishment around all the parts and periphery of 
each plant’s roots, throughout the whole period 
of its existence. The powers by which the soil 
achieves so great and complicated results are 
mainly its own mechanism, the chemistry of its 
own ingredients, and the agencies of moisture, 
air, heat, light, and electricity ; and the methods 
and intricacies in which these work and co-ope- 
rate, so far as they have been yet investigated, 
are a most imposing instance of the beauty and 
complexity, the wisdom and magnificence of the 
physical ordinances of the all-beneficent Creator. 
A simple glimpse at them—sufficient for farming 
purposes, and also for setting the mind a-think- 
SOIL. 
ing—is afforded by the following extract from a 
paper by Dr. Madden :—“ The mineral or perma- 
nent constituents of soil are capable of being 
divided into two distinct classes, independently 
of their chemical nature, viz., into coarse and 
fine, or into. visible particles and impalpable 
powder. The impalpable matter of soil contains 
all its most important ingredients ; for the re- 
mainder, or coarse particles, contains, in addi- 
tion to pure mineral matter, merely the crude 
undecomposed vegetable fibre, &c., which is 
utterly useless to plants until, by putrefaction 
or otherwise, it becomes disintegrated and inti- 
mately combined with the impalpable matter. 
The use of the coarser parts is therefore merely 
to render the soil more permeable to moisture, 
air, heat, &c., and in this manner to assist me- 
chanically in the preparation of the food of 
plants. When manure is added to soil, the follow- 
ing series of changes takes place :—1. The soluble 
matters are washed away from the straw and 
other undecomposed substances, by the first rain 
that falls, and, sinking into the earth, are imme- 
diately absorbed (supposing no plants are growing 
in the neighbourhood) by the impalpable matters 
of the soil. 2. If the soil should not have been 
previously rich, a certain quantity of the soluble 
manure will enter into chemical combination 
with the sand, clay, and chalk, of which the im- 
palpable matter is composed, and thus be ren- 
dered insoluble, and consequently for the pre- 
sent useless. 3. But should the finely divided 
parts of the soil be already saturated with or- 
ganic matter,—which, however, as above stated, 
will have been rendered insoluble by chemical 
combination,—the newly added soluble matter 
is, nevertheless, absorbed by the mass, although 
now it acts in a totally different manner. 4. 
The soluble organic matter of manure, when 
brought into contact with insoluble organic mat- 
ter, of whatever origin, acts as a ferment upon 
it, and causes it to undergo various changes, by 
which the chemical attraction between it and 
the clay, sand, chalk, &c., are overcome, and 
consequently it again becomes free in a soluble 
state, or, in other words, in a fit state for ab- 
sorption by plants. 5. But when, by the opera- 
tions of tillage, any part of the chemically com- 
bined organic matter is brought sufficiently near 
the surface to come freely in contact with air, 
a different series of changes takes place; ox¥gen 
is absorbed, and the organic matter is in this 
manner changed in its nature, and rendered 
much less easily decomposed, and, in fact, although 
no longer combined with the clay, chalk, &c., re- 
quires the addition of fermenting matters, or 
some alkaline salt, in order that it may be again 
rendered capable of solution. 6. At this point, 
the saline impregnations of soil come into play, 
and none more so than common salt or muriate 
of soda. This exists in almost every manure, so 
that it very generally is to be found in all culti- 
When this salt is brought into con- 
vated soil. 
