378 
THE COTTAGE GARDENER. 
[Septembeb 18 . 
for it is a result of experience, to which we know of no 
exception, that a plant contains more of any given 
earth if grown in a soil where it predominates, than 
if gi'own in a soil where it is in less profusion. This 
fact was pointed out by Saussure, who found that the 
llliododendron ferrugineum, when growing on the cal¬ 
careous formation of Mount Java, contained in its 
ashes 43.25 per cent, of carbonate of lime, but only 
0.75 of silica. On the other hand, the ashes of the 
same plant, from the granitic district of Mount Brevere, 
contained 2.0 per cent, of silica, but only 16.75 of car¬ 
bonate of lime. 
However varying in the proportions, yet every soil is 
composed of silica, alumina, lime, magnesia, oxide of 
iron, salts, and animal and vegetable remains. The 
most important consideration is, what proportions those 
are which constitute a fertile soil. 
The beau ideal of a fertile soil is one which contains 
such a proportion of decomposing matter, as to keep 
the crop growing upon it always supplied with food in 
a state fit for introsusception, yet not so superabun¬ 
dantly as to render the plants too luxuriant, if the 
object in view is the production of seed: but for the 
production of those plants whose foliage is the part in 
request, as spinach, or the production of edible bulbous 
roots, as onions, which have a small expanse of leaves, 
so as to be almost entirely dependent upon the soil for 
nourishment, there can scarcely be an excess of decom¬ 
posed matter presented to their roots. Spinach, on rich 
soils, will yield successive cuttings; the same with 
asparagus; the latter, especially, demands abundant 
applications of nourishment to its roots; since, like the 
onion, it has little foliage and slightly fibrous roots, at 
the same time that, like the spinach, it has to afford 
repeated cuttings, which, requiring a repeated develop¬ 
ment of parts, need abundant food, and that in the 
immediate neighbourhood. 
A soil with a just proportion of decomposing matter, 
which insures that it will be capable of absorbing 
moisture during the droughts of summer from the 
atmosphere, as the most fertile soils are always the 
j most absorbent, yet it must not be too retentive of 
j moisture, which is the case in such soils as contain 
too much alumina; neither must it too easily part with 
| it, which is a characteristic of those which contain an 
j excess of silica. A subsoil of gravel mixed witli clay is 
j the best, if not abounding in oxide of iron, for clay alone 
retains the moisture on the arable surface in too great 
I an excess; and sand, on the contrary, carries it away 
j too rapidly. It is, however, evident, that to insure 
| these desiderata in any soil, at all seasons, is impossible; 
, and it is as manifest that a soil that would do so in one 
! climate would fail in another, if the mean annual tem¬ 
perature of them should differ, as well as the amount in 
! inches, of rain which falls during the same period. 
Since, in the western parts of England, more than twice 
as much rain occurs as in the most eastern counties, 
or in the proportion of 42 to 19, a soil in the east of 
England, for any given crop, maybe richer and more tena¬ 
cious than the one required for it on the western coast. 
Alumina, or clay, imparts tenacity to a soil when 
applied; silica, or sand, diminishes that power; whilst 
chall: and lime have an intermediate effect, rendering 
heavy soils more friable and light soils more retentive. 
These simple facts are important; two neighbouring 
fields, by an interchange of soils, being often rendered 
fertile, which, before, were unproductive, from being in 
the extremes of heaviness and lightness. 
From these statements it is evident, that no universal 
standard, or recipe, can be given for the formation of a 
fertile soil, but one, the constituents of which approach 
in their proportions to those of the following one, cannot 
bo unproductive in any climate. It is a rich alluvial 
soil, which Mr. Sinclair, in his invaluable Hortus 
Gramineus Woburnensis, gives as being the most fertile 
for the grasses. 
Fine sand, 115; aluminous stones, 70; carbonate of 
lime, 23; decomposing animal and vegetable matter, 
34; silica, 100; alumina, 28; oxide of iron, 13; sul¬ 
phate of lime, 2 ; soluble, vegetable, and saline matter, 
7; loss, 8, total, 400. 
We have already stated what constitutes a fertile soil; 
it may be added, that, to constitute one eminently such, 
a large proportion of its earthy particles must be in a 
minute state of division, and the more minute, the more 
fertile it will be. In the above analysis, 185 parts only 
were separable by sifting through a fine searce, 215 
parts were impalpable; whereas poorer soils will often 
have 300 parts coarse matter to every 100 of finely pul¬ 
verized constituents. 
In affording warmth to plants, the earth is of consi¬ 
derable importance, and the power of accumulating 
and retaining it varies as much in soils as the propor¬ 
tions of their constituents. Sir Humphrey Davy found 
that a rich black soil, containing one - fourth of 
vegetable matter, had its temperature increased in an 
hour from 65° to 88° by exposure to the sunshine, ! 
whilst a chalky soil was heated only to 69° under similar 
circumstances; but the first, when removed into the I 
shade, cooled in lialf-an-hour 15°, whereas the latter 
lost only 4°. This explains why the crops on light- 
coloured tenacious soils are, in general, so much more ; 
backward in spring, but are retained longer in verdure 
during autumn, than those on black, light soils; the I 
latter attain a genial warmth the more readily, but 1 
part with it with equal speed. 
Different plants affect different soils. Every gar- I 
dener must have observed that there is scarcely a 
kitchen-garden but has some particular crop which it 
sustains in luxuriance far superior to any other garden j 
in its neighbourhood, or to any other crop that can be ! 
grown on it. A garden we once cultivated, without the 
preparation of an artificial soil, would not produce the 
common garden cress ( Lepidium sativum), whilst the 
raspberry was remarkably luxuriant. That the compo¬ 
sition of a soil has a main influence in these pecu¬ 
liarities is certain. 
