THE CULTURE OF TOBACCO.—NO. II. 
203 
between the statement now made, that enough 
carbonic acid and ammonia can he obtained from 
the mineral earth to support luxuriant vegetation , 
and the previous assertion, that a certain class of 
plants are to be found only on soils rich in vegeta¬ 
ble matter. There is however no contradiction, 
but a truth of great interest to the farmer involved 
in these facts. They are both practically correct, 
both made the basis of successful agriculture in 
extensive districts of country, and both lauded to 
the skies as the true method of culture. As a 
proof I refer the reader to part I., vol. 4 of the Jour¬ 
nal of the Royal Agricultural Society, he will find, 
beginning at page 267, an account of the practice of 
paring and burning resorted to in the Roothings Dis¬ 
trict of England, with its great success. Here are 
farmers laying down land to meadow, for the pur¬ 
pose in a few years of breaking it up to burn, when 
it has accumulated vegetable matter; and when 
other equally intelligent farmers would consider it in 
a fine condition to turn in as an improvement to the 
land. Both are right in their practice, there may 
be a difference in expense, which I will not now 
consider, but both operations, although come at as 
the result of experience, and of great antiquity, are 
yet founded upon the very same scientific principle 
and accomplish the same indication. 
Again, we learn by the result of the foregoing 
practice, as well as from investigations with char¬ 
coal, that those plants such as tobacco, Jamestown- 
weed, wheat, &c., which do not draw sufficient 
nitrogen from the air for luxuriant growth, may be 
abundantly supplied in a highly porous soil, solely 
of mineral earth, without humus. That decaying 
vegetable matter is not to them food, but only the 
gaseous bodies which they yield by decay, that the 
same gases absorbed by certain porous minerals 
from the atmosphere are adequate to their develop¬ 
ment. 
The farmer, therefore, is put in possession of an 
important principle, which may be satisfied by 
very dissimilar practice. He learns that vegetable 
matter is unnecessary to fertility, where his soil is 
sufficiently ameliorated by burning for increased 
porosity, or that if burning is improper, as in 
sandy and lime-stone soils, he can secure the object 
aimed at by impregnating the land with vegetable 
matter or adding charcoal or burnt clay from else¬ 
where. 
But the pulverization of the soil does not im¬ 
prove it merely in a mechanical sense, there is 
another great advantage gained. It assists in a 
very important manner in attaining the great ob¬ 
ject of increasing the amount of saline matter ren¬ 
dered soluble. I here disregard all consideration 
of porosity, and suppose the mineral earth as re¬ 
duced to an extremely fine powder, or at least of¬ 
fering an immense amount of surface if not in fine 
powder. A highly porous substance, as charcoal 
or chalk, does not expose to the air merely its vis¬ 
ible superficies, but every pore and cell presents 
its sides and cavities. It is this 'extent of actual 
surface which I am considering, and not the me¬ 
chanical size of the particles, although it is possible 
to attain immense surface by reducing them con¬ 
siderably. In the loose, friable soil, saline matter 
is rendered soluble much more rapidly than in the 
adhesive and hard masses. For, as is well known, 
the surfaces of solids increase in a much higher pro¬ 
gression than their diameters. The smaller there¬ 
fore the particle, or the more porous the structure, 
the greater the extent of surface exposed, and the 
larger the quantity upon which the carbonic acid 
water and other solvents can act. Much more wa¬ 
ter is held by such land, and with the gaseous sub¬ 
stances always present, the greater the rapidity 
with which saline substances are dissolved. With, 
respect to burnt lands there is an additional advan¬ 
tage which is of a chemical character, viz: the fa¬ 
cility with which certain silicates are dissolved; on 
this topic however I may treat hereafter. 
The science of agriculture is not so transparent 
an affair as many persons suppose; it is not the 
perusal of a theoretical treatise that is sufficient to 
convert the tyro into a sage. Even Tull, who, al¬ 
beit without much science, was an exceedingly 
good observer, fell into a lamentable error when 
he supposed that friability of soil was the only es¬ 
sential to fertility. There are soils with a maxi¬ 
mum fineness which are defective. I have had 
during the present summer, an opportunity of 
meeting with a very striking case, in a specimen 
submitted to me for analysis by R. L. Pell, Esq., 
which was so remarkable for its fineness, that on 
showing it to an experienced farmer he pronounced 
it extremely fertile ; yet it was barren in conse¬ 
quence of the want of lime, as was developed by 
analysis. Therefore we repeat, that the necessary 
saline matters must be present. 
So contradictory is the practice of paring and 
burning to the more common method of accumula¬ 
ting vegetable matter in the soil, that those farm¬ 
ers who have never adopted the former are in¬ 
credulous about its expediency. In the first, the 
vegetable matter accumulated by grass roots is 
made the fuel; in the ordinary method, the same 
organized substances are treasured up as the great 
acquisition of the farmer. It is in consequence of 
turning so much attention to one only of these 
processes that Liebig and Boussingault respectively, 
have advocated theories of agriculture so dissim¬ 
ilar. 
Liebig, in his last work, lays down the doctrine 
that saline matters are the true and only fertilizers ; 
while Boussingault, impressed with the great ad¬ 
vantages of ammonial substances, declares that the 
value of manures is directly as the nitrogen they 
contain. These views, so discordant, are never¬ 
theless the expressions of the culture of different 
countries. While the husbandman of Flanders 
and China knows nothing in nature equal in fertil¬ 
ity to urine, the Egyptian dresses his soil with the 
ashes only of camel’s dung, or to bring the prac¬ 
tice more clearly before our ideas, he burns the 
stable manure for the sake of the ashes. In the 
same way, in Europe, more especially in the Brit¬ 
ish isles, vegetable matter of the soil is burnt and 
the ashes only retained. Both these national 
practices a.re successful. In the opinion of the 
people of Flanders, Liebig is wrong and Boussin¬ 
gault right; in Egypt Liebig is right and Boussin¬ 
gault wrong. These dissensions are unfortunate. 
Agriculture as an art, has been the centre of the 
most contradictory notions; but science admits only 
