A CONSOLIDATION OF BUEL’S CULTIVATOR AND THE GENESEE FARMER. 
Cult. Vol. VIII.—No. 5, 
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“ TO IMPROVE THE SOIL AND THE MIND.” 
Notice of Liebig’s Organic Chemistry, applied to 
Agriculture. 
It is but comparatively a few years since the opinion 
that science could do aught for agriculture was scouted 
by the great mass of mankind, and particularly by those 
most interested, the farmers themselves. The know¬ 
ledge requisite for tilling the earth was supposed to 
come by instinct, or be hereditary, and the idea of im¬ 
provement in husbandry was considered on a par with 
the vagaries of Paracelsus, or the seekers for the phi¬ 
losopher’s stone. This is the more surprising, since 
the slightest investigation would have shown there is 
no pursuit of man where the deductions of science are 
more useful, or severe and carefully conducted experi¬ 
ments more likely to be amply repaid. The discovery 
of the bases of the alkalies by Davy, gave a new im¬ 
pulse to the inquiries which had been instituted into vege¬ 
table physiology, and that truly great man embodied 
the mass of facts he had discovered, and the theories 
deduced from them, in his volume on Agricultural 
Chemistry. That volume may be said to .have opened 
a new era in the pursuit of Agriculture, showing as it 
did, that the most important operations of the farmer 
depended on a combination of physical and chemical 
cadses. Great, however, as was the advance made by 
Davy, some of his theories were found untenable, 
some of the practices he recommended unsuitable ; still 
inquiry had been awakened, scientific men had been 
taught that the application of science to agriculture was 
practicable and necessary, and the utility of improved 
processes in tilling the soil made apparent to all who 
were willing to investigate, or not too proud to be 
taught. The French, never behind where the discove¬ 
ries or the applications of science are concerned, soon 
followed in the path marked out by Davy, and Count 
Chaptal, one of the ablest men France has produced, 
published his ‘ Chemistry applied to Agriculture,’ a 
capital work, and one which is perhaps more generally 
known than any that has been written on the subject. 
It is one of the volumes in the excellent series issued in 
by the Harpers for School Libraries, and ought at least 
to be found in every school district in the state. Chap¬ 
tal was aware that his work was imperfect, but the 
great learning,and unwearied perseverance brought to the 
task by him, evidently left little to expect, until farther 
advances in science should give an additional impulse to 
the chemistry of agriculture. That time seems to have 
arrived. The vast resources of the German Universi¬ 
ties, the patient research so characteristic of the peo¬ 
ple, the numberless discoveries which have been made 
in vegetable physiology, and the patronage and influ¬ 
ence of the government have all been enlisted in the 
promotion of agriculture, and to effect this, no pains 
have been spared to ascertain the laws that govern the 
germination, nutrition, and consequent growth of 
plants. The results of these researches have been em¬ 
bodied in the volume, the title of which is placed at 
the head of this article. Prof. Liebig has given to the 
public a work to be read and studied ; one that com¬ 
mands assent to the positions assumed by the clearness 
and force of the arguments ; and which, if not correct 
in every particular deduction, will, we are confident, 
notwithstanding the novelty of some of the positions 
assumed by him, be found to be sustained in the main 
by facts and experience. 
In the notice we propose to give of Dr. Liebig’s vo¬ 
lume, we shall endeavor to point out the most promi¬ 
nent features of his system, and as far as possible in 
his own language, certain that we cannot fill a page or 
5 
ALBANY, N. Y. MAY, 1841. 
two in a manner more acceptable to the intelligent rea¬ 
ders of the Cultivator. 
All former writers on the subject of Agriculture, 
have based their systems on the commonly received 
opinion, that the nutrition of plants is mostly derived 
from the vegetable mold, humus, or geine, existing in 
the soil. From this position Prof. Liebig dissents, and 
this difference it will be seen is fundamental. 
Carbon, water, and ammonia, contain the elements 
necessary for the growth of plants and animals ; the 
manner of their derivation is the point at issue. The 
carbon which constitutes the solid part of vegetables, 
has been attributed to humus , with the exception of the 
supposed small portion ascertained by Priestly, to be de¬ 
rived from the atmosphere in the shape of carbonic gas. 
The question is thus stated by Liebig : 
“The opinion that the substance called humus, is extracted 
from the soil by the roots of plants, and that the carbon enter¬ 
ing into its composition, serves in some form or other to nour¬ 
ish their tissues, is so general and firmly established, that 
hitherto any new argument in its favor has been considered 
unnecessary; the obvious difference in the growth of plants, 
according to the known abundance or scarcity of humus in the 
soil seemed to afford incontcstible proofs of its correctness. 
Yet this position, when submitted to a strict examination, is 
found to be untenable, and it becomes evident from the most 
conclusive proofs, that humus, in the form in which it exists in 
the soil, does not yield the smallest nourishment to 'plants. 1 ’ 
The arguments used by Liebig, to establish this po¬ 
sition, are based on numerous and varied experiments ; 
such as the facts that pure humus is very sparingly so¬ 
luble in water at any time, and if once dried, or even 
frozen, is perfectly insoluble ; that the best mold when 
treated in water, leaves it colorless, and less than 
100,000th. part of organic matter is dissolved ; that the 
quantity of humus in a forest or meadow is constantly 
accumulating, although a certain quantity of carbon in 
the shape of wood or hay is annually taken off; and 
that if the alkalies, lime, or ashes, fit it for assimila¬ 
tion, the salts so formed are so difficult of solution, that 
were all the water that falls on a field to be saturated 
with the humates, they would prove entirely inadequate 
to furnish the carbon of a field of wheat or beets. 
Since then the carbon of plants cannot be derived 
from the soil, it is evident it must be derived from the 
atmosphere. The woody fibre of plants, partially de¬ 
cayed, is called humus, and mold is the product of this 
complete decay of the woody part of plants. Prof. 
Liebig says : 
“In attempting to explain the origin of carbon in plants, it 
has never been considered that the question is intimately con¬ 
nected with the origin of humus. It is universally admitted 
that humus arises from the decay of plants. No primitive hu¬ 
mus therefore can have existed, for plants must have preced¬ 
ed the humus. Now, whence did the first vegetables derive 
their carbon ? and in what form is the carbon contained in the 
atmosphere ?” 
The conclusion to which Prof. Liebig arrives, is, 
that plants derive the carbon exclusively from the de¬ 
composition of carbonic acid, chiefly and often entire¬ 
ly supplied to them by the atmosphere. Humus or 
vegetable mold is only valuable as a source of carbonic 
acid, which it emits very slowly. Humus being the 
product of vegetable life, there is no more reason to 
suppose, that admitting it were absorbed by plants, it 
would aid in their nutrition, than that sugar, starch, 
and gum, which humus much resembles, should do so ; 
but it is well known that these substances, although they 
may be absorbed by plants, are never assimilated, or in 
other words are never available as the food of plants. 
Prof. Liebig thus describes the office of humus : 
“Humus supplies young plants with nourishment by the 
roots, until their leaves are matured sufficiently to act as ex¬ 
terior organs of nutrition; its quantity heightens the fertility 
of a soil, by yielding more nourishment in this first period of 
growth, and consequently by increasing the number of organs 
of atmospheric nutrition. Those plants which receive their 
first food from the substances of their seeds, such as bulbous 
plants, could completely dispense with humus; its presence 
is useful only so far as it assists and increases their develop¬ 
ment, but it is not necessary,—indeed, an excess of it at the 
commencement of their growth is, in a certain measure, in¬ 
jurious.” 
Although humus is thus divested of the high place 
usually assigned it in the nutrition of vegetables, still 
its functions are very important, and we add Prof. Lie¬ 
big’s account of these, illustrating as the extract does, 
the advantages of deep and thorough tillage : 
“ The decay of woody fibre, (the principal constituent of all 
plants,) is accompanied by a. phenomenon of a peculiar kind. 
This substance, in contact with air or oxygen gas, converts the 
latter into an equal volume of carbonic acid, and its decay 
ceases upon the disappearance of the oxygen. If the carbonic 
acid is removed, and oxygen replaced, its decay recommences, 
that is, it again converts oxygen into carbonic acid. * * * 
Humus acts in the same manner in a soil permeable to the air 
as in the air itself; it is a continued source of carbonic acid, 
which it emits very sloWly. An atmosphere of carbonic acid, 
Cult, & Far, Yol, II,—No, 5 , 
formed at the expense of the oxygen of the air, surrounds every 
particle of decaying humus. The cultivation of land, by till¬ 
ing and loosening the soil, causes a free and unobstructed ac¬ 
cess of air. An atmosphere of carbonic acid is therefore con¬ 
tained in every fertile soil, and is the first and most important 
food for the young plants which grow in it. 
“ In spring, when those organs of plants are absent, which 
nature has appointed for the assumption of nourishment from 
the atmosphere, the component substance of the seeds is ex¬ 
clusively employed in the formation of the roots. Each new 
radicle fibril which a plant acquires, may be regarded as con¬ 
stituting at the same time a mouth, a lung, and a stomach. The 
roots perform the functions of the leaves from the first moment 
of their formation; they extract from the soil their proper nu¬ 
triment, namely, the carbonic acid generated by the humus. 
“By loosening the soil which surrounds young plants, we 
favor the access of air, and the formation of carbonic acid • 
and on the other hand, the quantity of their food is diminished 
by every difficulty which opposes the renewal of air. A plant 
itself effects this change of air at a certain period of its growth. 
The carbonic acid, which protects the undecayed humus from 
further change, is absorbed and taken away by the fine fibres 
of the roots, and by the roots themselves; this is replaced by 
atmospheric air, by which process the decay is renewed, and 
a fresh portion of carbonic acid formed. A plant at this time 
receives its food, both by the roots and by the organs above 
ground, and advances rapidly to maturity. * * * * 
“ The size of a plant is proportional to the surface of the or¬ 
gans which are destined to convey food to it. A plant gains ano¬ 
ther mouth and stomach with every new fibre of root, and eve¬ 
ry new leaf.” 
The important practical inferences which may be 
drawn from these facts, will be apparent to every re¬ 
flecting mind. The advantages of deep plowing, fre¬ 
quent stirring the surface, application of vegetable mat¬ 
ter or manure, and the necessity of perfect seeds, pre¬ 
sent themselves at once. 
Hydrogen is constantly present in the structure of 
plants, and is the base of the oils, gums, resins, caout¬ 
chouc,- &c. As plants possess the property of decom¬ 
posing water, and as there is no other body from which 
they could derive this substance, the hydrogen doubt¬ 
less, arises from this source. Nearly all vegetable 
structures contain hydrogen in the form of water, but 
the hjrdrogen which is essential to their constitution and 
the presence of the products named, cannot exist in 
them in the state of water, but is prepared by its decom¬ 
position. This furnishing a proper supply of hydrogen, 
is one of the important services which water renders to 
vegetation. 
It has long been known that nitrogen acts a most im¬ 
portant part in vegetation, but physiologists have not 
been agreed as to the manner in which it is furnished, 
or the source of the supply. In unravelling these mys¬ 
teries, or in answering the question, “ How, and in 
what form does nature furnish nitrogen to vegetable al¬ 
bumen and gluten, to fruits and seeds Prof. Lie¬ 
big has been peculiarly happy, and this part of his 
work may be deemed the most original and luminous of 
his pages : 
“ Plants, as we know, grow perfectly well in pure charcoal, 
if supplied at the same time with rain water. Rain water can. 
contain nitrogen only in two forms, either as dissolved atmo¬ 
spheric air, or as ammonia. * * * There are numerous 
facts showing, that the formation in plants of substances con¬ 
taining nitrogen, such as gluten, takes place in proportion to 
the quantity of this element which is conveyed to their roots 
in the state of ammonia, derived from the putrefaction of ani¬ 
mal matter. * * * The nitrogen of putrified animals is 
contained in the atmosphere as ammonia, in the form of a gas, 
which is capable of entering into combination with carbonic 
acid, and of forming a volatile salt. Ammonia in its gaseous 
form, as well as all its volatile compounds, is of extreme 
solubility in water. Ammonia, therefore, cannot remain long 
in the atmosphere, as every shower of ram must condense it, 
and convey it to the surface of the earth. Hence also rain wa¬ 
ter must, at all times, contain ammonia, though not alway s in 
equal quantity. It must he greater in summer, than in spring 
or winter, because the intervals of time between the showers 
are in summer greater; and when several wet days occur, the 
rain of the first must contain more of it than that of the second. 
The rain of a thunder shower, after a long protracted drouth, 
ought for this reason to contain the greatest quantity, which 
is conveyed to the earth at one time.” 
We have often noticed the surprising effects produced 
by thunder storms on vines, such as the Solatium dul¬ 
camara, in giving a rapid growth, but while the theo¬ 
ry of Liebig explains the cause, or at least one of them, 
we have been inclined to attribute much to the effect of 
electric agency in the matter, a fact perfectly consis¬ 
tent, as experiments prove that currents of electricity, 
by increasing the vital activity of plants, prepare them 
to receive nutrition more rapidly. 
The great discovery made by Prof. Liebig, of the 
existence of ammonia in rain water, when its presence 
had never been suspected, was one of those happy ap¬ 
plications of science to the investigations of causes af¬ 
fecting plants, which can scarcely fail of the best re¬ 
sults in explaining many of the operations of tillage. 
Ammonia may always be detected in snow water. The 
inferior layers of snow which rest on the ground, al¬ 
ways contain greater quantities than that on the sur- 
