DIGGING, TRENCHING, ETC. 
159 
will be attained. This action of the roots is 
assisted by other conditions produced by 
pulverisation. Thus the capillary attraction 
of the soil is increased, and consequently its 
humidity is rendered more steady and uniform. 
In dry weather, when a consolidated soil would 
have become arid and unable to support vege- 
tation, a pulverised soil would be furnished by 
this capillary property from the moisture be- 
neath it, and it would also absorb with greater 
facility the nightly dews which fell upon it. 
The temperature of the soil is also heightened 
by pulverisation, and its more equable state of 
humidity condenses certain gases from the 
atmosphere, which become converted into food 
for the plants. The chief advantage, however, 
is that derived from the manner in which it 
increases the number of fibrous roots or mouths 
by which the plants are enabled to imbibe their 
food, from the more speedy and perfect pre- 
paration of this food, and from the greater 
regularity with which the latter, being so pre- 
pared, is conducted to the roots. 
Aeration, or the free admission of the 
atmosphere among the particles of the soil, is 
very beneficial ; some of the elements of the 
atmosphere being condensed, and thus supplied 
to the roots. In summer, one advantage of 
aeration is the thorough heating of the soil, 
which increases its capacity for absorbing 
moisture, and must materially assist the de- 
composition of what vegetable matters it may 
contain. In winter, aeration favours the 
minute mechanical division of the soil, by the 
freezing of the water which it contains ; for 
as water in the solid form occupies more space 
than when fluid, the particles of earthy matters, 
and of decomposing stones, are thus rent asun- 
der and crumble down into a fine mould, so 
that well-aerated soils thus receive an accession 
to their finer particles every winter. The 
action of the atmosphere will also disintegrate 
and sweeten such soils as may have become 
soured or soddened, if the cause of the latter 
condition has been removed. 
The intermixing of the particles of the soil, 
by the repeated processes of digging, trench- 
ing, &c. is favourable to its fertility. The 
heavier particles have a tendency to settle 
downwards, leaving the surface light and 
spongy, which tendency is sufiiciently checked 
by these operations, if they are frequent 
enough ; and thus the mechanical texture 
favourable to the increase of roots, the prepa- 
ration of food, and the drainage of superfluous 
water, is secured. Manures and composts, 
too, when added to a soil to aid its fertility, 
require to be intimately blended with its par- 
ticles, and this result is obtained during the 
processes of digging and trenching. 
Each of the operations referred to, claims a 
separate and detailed considex-ation. Before 
proceeding with these, however, it may be 
remarked, that dry weather is most proper for 
executing the whole of them ; and the soil 
should also be comparatively diy, that is, not 
so wet as to become pasty or adhesive from 
the necessary trampling by the feet. Nothing 
is so etfectually opposed to the pulverisation 
of the soil, which is one of the main objects 
to be effected, as the burying of any portion 
of it in this mortar-like condition ; and yet it 
is very commonly practised. Common-place 
operations of this kind are too often thought 
to be entirely independent of such consider- 
ations as that of the weather in which they 
are performed ; and yet it is not too much to 
say, that very many of the advantages of the 
operation are lost from inattention to this 
point. This evil is most serious in heavy clay 
soils ; and becomes of less importance when 
the soil is very light and sandy. Another 
point which should be borne in mind is, that 
snow does not improve the texture of the soil 
when dug or trenched in, and materially lowers 
its temperature by abstracting from it the heat 
it may possess. Whenever these operations, 
therefore, are performed at a time when snow 
is on the ground, it should not be turned in 
or mixed up with the soil : no harm will, how- 
ever, result from casting it, as the work pro- 
ceeds, 071 to the top of the turned-up soil. 
Dry frosty weather affords a very favourable 
time, for trenching especially ; but when it is 
possible, all those portions of the garden which 
are designed to benefit by exposure to frost 
in winter, should be dug or trenched in the 
autumn, or in the earlier part of winter, in 
order that the surface may be turned over 
during the continuance of frost, so as to expose 
a greater portion directly to the influence of 
the atmosphere. 
Dlcjfjing. — This operation consists in turn- 
ing over the surface-soil to the depth of from 
eight inches to a foot, or in technical language, 
" one spit deep ;" that is, the depth of the 
blade of the spade. This is done with the 
view of lightening up the soil to that depth 
for the reception of some fresh crop, or to mix 
in manure with the upper stratum of soil, or 
sometimes to bury down weeds and rubbish, 
with a view to producing a neat and orderly 
appearance. The first part of the operation 
is to remove a deep open furrow at one end, 
or along one side of the piece of ground to be 
dug. Digging cannot be carried on in a 
workman-like manner unless this furrow, 
technically a " trench," is of sufficient capa- 
city to admit of the reversal of the position 
of each spadeful of soil, as it is cast down. 
Taking the depth at one foot, the width of 
this trench should be about a foot, rather more 
than less. The earth which is taken out to 
form this trench should, if the piece of ground 
