SOIL. 
porous and easily permeable by air and moisture, 
while, at the same time, there is a sufficient sup- 
ply of matter in a state capable of undergoing 
chemical changes; and it must have mingled 
with it a sufficient supply of organic matter, in a 
state capable of decomposition by the action of 
air and water. To be fit for profitable cultiva- 
tion, it must be free from any mineral substance 
which is destructive of fertility ; it must be cap- 
able of being reduced to a sufficiently fine tilth, 
without an undue amount of labour; it must 
either be naturally capable of letting off any ex- 
cess of water which may fall upon it, or capable 
of being made to do so artificially by draining ; 
it must possess a structure which will allow the 
decomposition of organic matter mingled with it 
to proceed ata regular rate, being neither so fast 
as to waste the manure, nor so slow as to keep it 
too long fresh; and its situation must be such as 
to admit of all the operations of husbandry being 
performed in a proper manner, without occupy- 
ing too much time, and must have a climate 
which shall give full promise of the plants arriv- 
ing at perfection. To be capable of continued 
cropping, it must be ploughed and harrowed, and 
subjected to any other operations which may be 
necessary for thorough cleaning and pulveriza- 
tion ; it must have its supply of organic matter, 
and part also of its mineral ingredients, renewed 
by returning to it from time to time in the shape 
of manure, what has been removed in the form 
of crops ; and it must be kept in an active state, 
by having fermenting substances added to it at 
certain periods. And if it be in a bad or com- 
paratively unproductive condition, then, in order 
to be freed from any great natural faults which 
hinder or impair its fertility, or to acquire such 
addition of new powers or increase of old ones as 
shall materially enhance its productiveness, or to 
recover the possession of any aggregate powers 
which it may have lost by overcropping or mal- 
treatment, it must undergo either draining, lim- 
ing, trenching, subsoil-ploughing, bare-fallowing, 
paring and burning, change of texture by inter- 
mixture of mineral manure, or whatever other of 
the operations mentioned in the preceding sec- 
tion, or of any two or more of them, may be best 
suited to improve it. 
The comparative effects of vegetation upon soil 
in its natural or totally neglected condition, and 
in a condition of cultivation, may be stated as 
follows :— Uncultivated soil, however rich, be- 
comes gradually less and less fertile, until it has 
attained the condition either of moor or marsh; 
it retains its luxuriance for the greatest length 
of time, when covered with forest trees and other 
large vegetables ; it produces successive crops of 
different kinds, or, in other words, maintains a 
sort of natural rotation; when any species of 
plant on it disappears, its place is supplied by 
one of less value as an article of food, so that the 
richest pasture comes in time to produce only 
263 
and yet, though the natural produce of unculti- 
vated soil thus uniformly decreases in value, the 
soil itself becomes progressively richer, so that, 
when brought under the plough, it will yield 
much larger returns than could be expected from 
its spontaneous produce. Soil which is regularly 
cultivated or continually ploughed yields its 
nourishment in much greater abundance, and 
with greater ease, to plants growing upon its 
surface; the facility with which the productive 
powers of well cultivated land are diminished, 
depends on its organized matter being more 
easily converted into compounds soluble in air 
and water ; the decrease of fertility in carelessly 
cultivated soil depends, in addition to the above 
circumstance, upon a diminution in the propor- 
tion of its impalpable matter ; cultivated land, 
when properly taken care of, becomes gradually 
richer and richer, notwithstanding the increased 
quantity of produce annually removed from it; 
if the same plant be cultivated for several years 
successively upon the same spot, the soil much 
more rapidly decreases in fertility than when a 
variety is kept up ; and some of the most valu- 
able mineral constituents of soil decrease in 
greater rapidity in proportion to the greater care 
bestowed upon its cultivation, altogether inde- 
pendent of the portions removed by the crops. 
The particular principles involved in the suc- 
cessful cultivation of the numerous and widely 
different kinds of field crops, may, in a main 
degree, be deduced by intelligent farmers from 
the five following facts:—1. All plants require 
a good supply of nourishment during the first 
periods of their growth, for without this they 
will never arrive at perfection. If, therefore, 
nature has not provided a stock of nourishment 
laid up in the seed, it must be supplied artifi- 
cially. Seeds, therefore, which are devoid of this 
natural supply of food, must be provided with 
an abundance of well fermented manure, unless 
it is required that the first stages of their de- 
velopment should occupy a considerable period 
of time. 2. Many plants have more than one 
method of propagating themselves; if, therefore, 
one method is more desired than another, means 
should be used to prevent the others from being 
accomplished, as by preventing the one, you in- 
crease the vigour of the other. 3. Plants lay up 
a store of nourishment for the next year, either 
in the wood, as in perennials, or in the seeds, as 
in annuals. 4. The starch of plants is always 
contained in cells, formed of a substance con- 
taining azote; and, consequently, there exists a 
fixed proportion between the quantity of azote 
composing the cells, and the amount of starch 
contained in them ; hence it follows, that to in- 
crease the quantity of starch in a plant, you 
must increase its supply of azote, although starch 
itself contains no trace of this element. 5. In 
all parts of a plant there is an exact proportion 
between the various elements entering into its 
the coarsest and most worthless species of grass; | composition, so that an addition to one of them 
