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(EECTURES ON AGRICULTURE,

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2 BY “
= M. GEORGE VILLE,

a PROFESSOR OF VEGETABLE PHYSIOLOGY AT THE MUSEUM OF NATURAL
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HIGH FARMING WITHOUT MANURE.

SIX

LECTURES ON AGRICULTURE,

DELIVERED AT THE EXPERIMENTAL FARM
AT VINCENNES.

BY

M. GEORGE VILUE,

PROFESSOR OF VEGETABLE PHYSIOLOGY AT THE MUSEUM OF NATURAL

HISTORY, PARIS.

BOSTON :
PRESS OF GEO. C. RAND & AVERY.
1866.

(™ EXCHANGE

Bos. AUTH.
Mr 3 ‘06

SONTHNTS.

LECTURE FIRST.
(5th June, 1864.) PAGE
ON THE SCIENCE OF VEGETABLE PRODUCTION, o> ‘ente) « Seite

LECTURE SECOND.
(12th June, 1864.)

ON THE ASSIMILATION OF CARBON, HYDROGEN, AND OXYGEN
OY EARS ee ee erica: | gh ees, 8 iw) | ee a

LECTURE THIRD.
(19th June, 1864.)

ON THE MECHANICAL AND THE ASSIMILABLE ELEMENTS OF
PEE) SOM 5) a) Sh Dane ah oh eho et ae he ee PRE Eee oe

LECTURE FOURTH.
(26th June, 1864.)

ON THE ANALYSIS OF THE SOIL BY SYSTEMATIC EXPERIMENTS
IN CULTIVATION ° . . . . ° e . ° . e e . e e . s 46

LECTURE FIFTH.
(3d July, 1864.)

ON THE SOURCES OF THE AGENTS OF VEGETABLE PRODUC-
LIONS . . © . . . . . . . . . . . e . bd Ld . . . 66

1V CONTENTS.

LECTURE SIXTH.
(10th July, 1864.) PAGE

ON THE SUBSTITUTION OF CHEMICAL FERTILIZERS FOR FARM-
YARD MANURE e e s e J e . . . e e e e . ,’ . . 86

APPENDIX ) . ° . e e e ® ° e e e e . e . e s .

TRANSLATOR’S PREFACE.

THE researches of M. Ville, which are now
placed at the head of the most important discover-
les science has yet made for the benefit of agricul-
ture, were, like all innovations, received at first
with something more than coldness and indiffer-
ence. It hasever been thus: the most pregnant
ideas, those destined to exercise the happiest in-
fluences upon society, are always accepted with
reluctance; for they disturb preconceived no-
tions, they upset so many plausible theories, and
humble our conceit ; therefore they are always
met with objections and opposition from your
“practical men” alarmed at the scientific rigor
of the formula, and from savants always disposed
to oppose one theory by another. But true sci-
ence ultimately makes its way, notwithstanding,
by virtue of that providential power which, amid
a host of obstacles and diversions, finally achieves
progress. — .

vl

Many chemists, even the most illustrious, had
devoted themselves to the study of the natural
agents of fertility, previously to M. Ville. Their
investigations led to most important results; but
in spite of the advantages they offered, they left a
general impression of insufficiency, and discour-
agement soon succeeded enthusiasm. Animil
charcoal and guano, for example, gave rich har-
vests, but it was soon found that they were expe-
dients, and not specifics. Even farm-yard manure
justified the title of perfect manure but very
incompletely. It did not always respond to
what was required of it, and moreover is not
sufficiently abundant to restore to the soil all that
is taken from it, as the residues of a harvest con-
sumed ata distance cannot all be returned to
the field, which, it may be said, leaves us with
exhaustion in prospective.

So true is this that, even where manure is col-
lected with the greatest care, the necessity for
supplying the evil with stimulants is still felt.
fossil manures present themselves to supply this
deficiency, and they certainly possess great
value, but do they unite every quality necessary |
to secure us against fresh disappointment? There
hes the pith of the question.

When agriculturists demand an analysis to test

vi

the richness of a field and repair its losses after
each harvest, they lose sight of the fact, that each
field has its own peculiar wants, and what will
suit one may not suit another.

It is by stating the problem in these terms that
M. Ville has arrived at its solution. He has
studied the appetites of each plant, or at least,
of those three great families of plants upon which
agricultural industry is mostly exercised, viz: —
the cereals, leguminous plants, and roots: and
he has deduced from this study the formula of a
normal manure.

There is nothing extravagant in sintine® that
light has thus replaced darkness, that order has
succeeded to chaos, and that the phantom of
sterility is laid. If, like all mundane things, the
system is perfectible, the specialization of ma-
- nures — or, to speak more correctly, the nutri-
tion of plants —is the law which will make agri-
culture pass from the condition of a conjectural
to that of a positive science.

To operate with greater certainty, M. Ville
removed every element of error or doubt from his
experiments, and proceeded by the synthetic
method. He took calcined sand for his soil, and
common flower-pots for his field. Ten years of
assiduous observation and experiment led him to

Vill

recognize that the aliment preferred by cereals
is— nitrogen ; by liguminous plants — potassa ;
by roots—the phosphates: we say the pre-
ferred element, but not the exclusive: for these
three substances, in various proportions, are
necessary to each and all, and even lime, which
humus renders assimilable, must be added.

These facts, proved in pure sand by means of
fertilizers chemically prepared, were next re-
peated in the soil ofa field on the Imperial farm
at Vincennes, at the expense of the Emperor,
who, with that sagacity and tact which marks
his every public act, recognized in M. Ville, even
at the time he was violently opposed and unpop-
ular, the man most capable of turning the con-
quests of science to the advantage of agriculture:
he extended a generous and powerful hand to
the professor, and the most complete success has
crowned his glorious initiative.

During the past four years curious visitors,
drawn to the farm by the report of M. Ville’s
experiments, have been shown a series of square
plots, manured and sown in conformity with rules
laid down to test their efficacy. Upon some of
these plots the seed has never been varied; the
same soil has been planted four times in suc-
cession with wheat, colza, peas, and beetroot:

1X

giving them, at the commencement, a supply of
the normal manure, and adding annually what M.
Ville terms the dominant ingredient, that is to
say, the special manure of the series. Upon the
other plots, the seed alternated during the qua-
ternary period at the expense of the normal ma-
nure, by changing the dominant according to the
nature of each plant introduced into the rota-
tion: and under these conditions, the crops have
reached to results of irrefutable eloquence.

But as a proof necessary to satisfy prejudiced
minds, side by side with the plots which had re-
ceived the complete manure, others were placed
in which one or more of the elements were
omitted. In the latter, vegetation was languid,
and almost nil, proportionally to the quantity and
quality of the absent ingredients, to such a de-
gree, that what was wanting could be ascertained
by the decrease of vigor in the plant. A _ little
practice thus leads to an appreciation of the
qualitative richness of a soil. For the suppression
of one of the principles of fertilization produces
in each vegetable family differences, which indi-
cate to the observer the part which each principle
performs, and the proportion in which it is ab-
sorbed. These experiments, the fundamental
bases of theory, have not, however, the regulat-

x

ing of agricultural practice for their object. M.
Ville assigns four years to the action of the nor-
mal manure, replenished after each harvest by
the dominant element; renewing this normal
manure, however, upon the first signs of a fall-
ing off in the crops.

By adding, according to M. Ville’s system, ni-
trogenous matter, phosphate of lime, and _po-
tassa, — that is to say, a normal or complete ma-
nure to calcined sand, the seed-wheat being
equal to 1, the crop is represented by 28.

Upon withdrawing the nitrogenous matter
‘from this mixture of the four elements, the crop
* fell to 8.83.

Upon withdrawing the potassa, and retaining
all the others, the crop only attained to the figure
6.57.

When the phosphate of lime was omitted, the
crop was reduced to 0.77: vegetation ceased,
and the plant died.

Lastly, upon abstracting the lime, then the
ete the maximum of which was represented by
23, was only 21.62.

From the above facts we draw these conclu-
sions:— that if the four elements of a perfect
manure, above named, act only in the capacity
of regulators of cultivation, the maximum effect

al

they can produce implies the presence of all four.
In other words, the function of each element de-
pends upon the presence of the other three.
When a single one is suppressed, the mixture at
once loses three-fourths of its value.

It is to be remarked, that the suppression of
the nitrogenous matter, which causes the yield
of wheat to fallfrom 23 to 8.33, exercises only a
very moderate influence upon the crop, when the
plant under cultivation is leguminous. But it
will be quite otherwise if,in such case, we remove
the potassa.

If we extend the experiment to other crops,
and successively suppress from the mixture one
of the four agents of production, we arrive at
the knowledge of the element which is most es-
sential to each particular crop, and also which is
most active in comparison with the other two.
For wheat, and the cereals generally, the element
of fertility, par eacellence, —that which exercises
most influence in the mixture, —is the nitroge-
nous matter. For leguminous plants, the agent
whose suppression causes most damage is po-
tassa, Which plays the principal part in the mix-
ture. For turnips and other roots, the dominant
element is phosphate of lime.

By employing these four well-known agents,

” <i

M. Ville’s system may well replace the old sys-
tem of cultivation. With him, the rule that ma-
nure must be produced upon its own domain is
not absolute. During four succeeding years, M.
Ville has cultivated, at the Vincennes farm, wheat
upon wheat, peas upon peas, and beetroot upon
beetroot: and he entertains no doubt that he
could continue to do so for an indefinite period,
the only condition necessary to be fulfilled being
—to return to the soil, in sufficient proportion,
the four fundamental elements above named.
Suppose we wished to cultivate wheat indefi-
nitely. We should at first have recourse to the
complete manure, and afterwards administer only
the dominant element, or nitrogenous matter,
until a decrease in the successive crops showed
that this culture had absorbed all the phosphate
of lime and potassa. As soon as a diminution in
the crops manifests itself, we must return to the
complete manure, and proceed as before.
Suppose that, instead of an exclusive culture,
it be desired to introduce an alternate culture in
a given field. We commence with the agent
that has most influence on the plant with which
we start. If that be a leguminous plant, we
at first administer only potassa. For wheat,
we should add nitrogenous matters. If we con-

” xiii
clude with turnips, we have recourse to phos-
phate of lime ; but when we return to the point
from which we started, all four elements must be
employed.

As may be seen, this system differs radically
from that hitherto adopted. It has not for its
basis a complex manure administered to the soil
by wholesale, in which we endeavor to turn all
its constituents to account by a succession of
different crops. In M. Ville’s system, he sup-
plies to the soil only the four governing agents
of production, which are added gradually, one
after another, and in such manner as to supply
each kind of crop with the agent that assures the
maximum yield.

The experiments at Vincennes were quite con-
clusive, but M. Ville wished to verify them ona
larger scale. For this purpose, land on the estate
of Belle Kau, near Donzére, in Dauphiny, was
placed at his disposal wherein to open a new field
of experiments. The results were just the same.
On the 4th of July last, an audience of two hund-
red farmers, and others interested in the progress
of agriculture, assembled under the lofty trees at
Belle Hau, to listen to the professor’s explana-
tions and witness the proofs of the soundness of
his new system.

ot
X1V

He stated that the experimental field, divided
into seven equal portions, was sown in November
last with “ Hallett Wheat.” One portion received
no manure at all; consequently the product, both
ears and straw, was weak and frail. Hach of the
other portions was fertilized with one of the sub-
stances which constitute wheat (phosphate of
lime, potassa, ime, and nitrogen). They pre-

sented a series of interesting products, the last of
which — that is to say, the most advantageous as
to yield — was reaped from that portion of the
soil fertilized with an artificial mixture of all the
constituent substances united.

Devoid of all scientific nomenclature, which
frequently embarrasses most agriculturists, M.
Ville’s lucid and brilliant exposé convinced the
most incredulous. Almost every auditor retired
with the firm resolution of repeating the pro-
fessor’s experiments for himself.

All manure must contain principles, mixed in
certain proportions, the combination of which is
indispensable. In this particular, M. Ville has
invented nothing, but limited himself to the spe-
cializing and better defining their effects, with-
out, however, forgetting those which are purely
mechanical. It remains now for practical men to
combine and prepare fertilizers of each kind, and

“XV

to apportion their application according to the
rules here laid down. This is a simple detail of
execution, and if we are compelled to have re-
course to chemical products to complete the ele-
ments of fertilization, they will not replace the
residues of animal consumption, nor render them
useless ; but will allow M. Moll’s beautiful for-
mula to subsist in all its truth. — “'lhe purifica-
tion of cities by the fertilization of the country.”
We believe we do not deceive ourselves in
affirming that the difficulties of the sewerage
question will be removed from the minds of all,
as they now are from those who have given’due
attention to the subject.

CHARLES MARTEL.

Ashford Cottage, Fortess Terrace,
Kentish Town.

ANALYSIS.

AGRICULTURE A SCIENTIFIC PROBLEM.—ALL KNOWN PLANTS ARE
COMPOSED OF FIFTEEN ELEMENTS ONLY, WHICH ARE SUBDIVIDED
INTO TWO GROUPS, THE ORGANIC AND THE INORGANIC, — PARALLEL
BETWEEN VEGETABLES AND MINERALS.— THE FORMATION OF THE
VEGETABLE DUE TO ORGANIC POWER, WHICH MODIFIES THE ORDI-
NARY PLAY OF AFFINITES.— NATURE, UNIFORM IN HER GENERAL
LAWS, DOES NOT PASS ABRUPTLY FROM THE MINERAL TO THE
VEGETABLE, BUT THROUGH A SERIES OF COMPOUNDS NAMED
TRANSITORY PRODUCTS OF ORGANIC ACTIVITY, WHICH ARE EITHER
HYDRATES OF CARBON OR ALBUMENOIDS.— THESE PRODUCTS PASS
INSENSIBLY FROM ONE STATE TO ANOTHER BY CHEMICAL RE-
ACTIONS.— THE ALBUMENOIDS CONTAIN NITROGEN, AND PRESENT
THEMSELVES UNDER THREE ESSENTIAL FORMS: INSOLUBLE, SEMI-
SOLUBLE, AND SOLUBLE, TO WHICH THE THREE TYPES, FIBRINE,
CASEINE, AND ALBUMEN CORRESPOND.—CHANGES THAT OCCUR.
DURING GERMINATION, AND DURING THE FORMATION OF THE SEED.
— THE GREATER PART OF THE WORK OF VEGETATION MAY BE RE-
FERRED TO THE RECIPROCAL ACTION OF THE HYDRATES OF CARBON,
ALBUMENOIDS, AND MINERALS, THROUGHOUT WHICH THE GENERAL
LAWS OF CHEMISTRY PREVAIL.—THE QUANTITY OF MINERAL
MATTER CONTAINED IN VEGETABLES IS 1N PROPORTION TO THE
ACTIVITY OF EVAPORATION.— THE DISTRIBUTION OF THE MINERAL
MATTER IN VEGETABLES OBEYS FIXED LAWS.— DEFINITION. —
VEGETABLES ARE COMBINATIONS OF A SUPERIOR ORDER TO MIN-
ERAL COMBINATIONS, BUT, LIKE THEM, DEPENDENT UPON THE AS-
SOCIATION OF THE FIRST ELEMENTS UNDER THE INFLUENCE OF THE
GENERAL LAWS OF CHEMISTRY.

LECTURE FIRST.

In consequence of the persevering efforts given to
the study of plants of late years, agricultural produc-
tion has been raised to the rank of a scientifie problem.
It is in this spirit that | have for many years studied it
at the Museum of Natural History. Here, my lan-
guage will be more simple, familiar, and practical; it
will, nevertheless, retain its scientific character, science
being the essential basis of every thing I have to tell
you.

If we seek to define the conditions which determine
vegetable production, the influences which modify its
growth, and the forces which govern its manifestations,
we must commence by going back to the elements of
vegetables themselves. We must separate from the
vegetable its organic individuality, and consider only
the chemical combinations of which it is the seat and
the result.

The analysis of all known vegetables or the products
extracted from them, leads to this very unexpected
fact, — that fifteen elements only concur in these innu-

merable formations. These fifteen elements, which,
2

alone, serve to constitute all vegetable matter, are sub-
divided into two groups : —
First — The organic elements, which are encountered
only in the productions of organized beings, and the
source of which is found in the air, and in water.

They are Carbon. Oxygen.
Hydrogen. Nitrogen.

Second — The mineral elements, which resist com-
bustion, and which are derived from the solid crust of
the globe.

They are Potassium. Phosphorus.
Sodium. Chlorine.
Calcium. Tron.
Magnesium Manganese.
Silicium. Aluminium.
Sulphur.

Vegetables are, in fact, and from the special point
of view where we place them, only the varied combi-
nations of which these fifteen elements are susceptible.
In the same way that a language expresses our most
delicate and profound thoughts, as well as the meanest,
by means of the small number of letters which compose
its alphabet — so do vegetable productions assume the
most varied forms and dissimilar properties by means
of these fifteen elements only, which compose the true
alphabet of the language of nature.

Now, if it be so, we are justified in likening the

4

vegetable to a mineral combination, a more complicated
one, doubtless, but which we may hope to reproduce in
every part, by means of its elements, as we do with
the mineral species. This proposition, how astonishing
soever it may appear to you, is nevertheless the exact
truth. To prove it to you, permit me to establish a
parallel between vegetables and minerals, from the dif-
ferent points of view which more especially character-
ize the latter. We will commence with their mode of
formation and growth. ,

First, we perceive only differences. A crystal sus-
pended in a saline solution, grows by the deposit of
moiecules on its surface, similar in composition and
form to those which constitute its nucleus. These
molecules, diffused through the solution, obey the laws
of molecular attraction, and thus increase the mass of
the primitive crystal. The vegetable, on the contrary,
does not find diffused vegetable matter in the atmosphere,
nor in the soil with which it is in contact. Through
its roots and leaves it derives its first elements from
without, causing them to penetrate into its interior, and
there mysteriously elaborates them to make them ulti-
mately assume the form under which they present
themselves to our eyes.

We can, nevertheless, say that the process of vegeta-
ble production has something in common with the for-
mation of a mineral. For in both cases we see a cen-
tre of attraction, which gathers up the molecules, &c.,
received from without. Inthe more simple case of the

+)

mineral, the combination of the elements is previously
accomplished ; only a mechanical grouping takes place.
In the more complex case of the vegetable, the combi-
nation and mechanical grouping are effected at the same
time, and in the very substance of the plant. In both
cases a formation is engendered by the union of definite
or definable material elements.

From the point of view of composition, vegetables
appear at first more simple, since they are derived from
fifteen elements. only, while at least sixty concur in the
production of minerals ; but in reality they are more
complex, since each plant always contains the fifteen
elements at once, while minerals, taken individually,
never contain but a very small number, five or six at
most. Among vegetables, the combination is also more
intimate. In minerals, each of the constituents pre-
serves up to a certain point, its individual properties.
In the sulphates, for example, it is easy to prove the
presence of sulphuric acid by adding baryta to it, which
gives the insoluble precipitate of sulphate of baryta in
these salts as well as in sulphuric acid itself. Besides,
in thus withdrawing the sulphuric acid from a sulphate,
we have not destroyed the sulphuric acid, we have only
displaced it. But with the group of elements which
form a vegetable, it is not so; in them, all individual
character disappears. Who can perceive the carbon, the
nitrogen, the potassa, &c., which constitute the plant?
Only the whole manifests its properties, and we cannot
separate an element from it, except by destroying it

6

past recovery. Notwithstanding these essential differ-
ences, we have, nevertheless, in both cases, to do with
material combinations, that is to say, with phenomena
of the same nature, one of which is more complicated
than the other ; they are two distant terms of the same
series.

Let us conclude this parallel by comparing the forces
which, in both cases, determine the grouping of the
elements. When attraction is exercised at great dis-
tances, in the planetary spaces, for example, it depends
only on the reacting masses, and not upon their nature ;
when, on the contrary, attraction is exercised in contact,
as in chemical combinations, it depends at the same
time upon the mass and the nature of its elements.
This new and more complex form of general attraction
is called affinity. Gravitation, the first term of the
series, which we call universal attraction, governs and
harmonizes the movements of the stars; affinity, the
second term of this same series, regulates the play of
mineral combinations.

If we examine the formation of vegetables from this
point of view, we shall see that it represents a still
more complicated case of universal attraction, a third
term of the series, if I may be allowed the expression.
Here, in fact, the result depends at the same time on
the re-acting masses, on the nature of the elements
present, and on the action of a new force, situated in
the embryo, which diffuses itself from thence through-
out the vegetable, and impresses its special stamp upon

yj

the combination produced. Take two seeds of the
same sort, having the same weight, remove from each
of these seeds a morsel also of the same weight, only
let one include the embryo in the amputation, and in
the other let the embryo be left out, and take instead a
fragment of the perisperm, then put both upon a wetted
sponge. The seed without embryo will soon enter into
a state of putrefaction, the other, on the contrary,
will give birth to a vegetable capable of absorbing and
organizing all the products resulting from the disor-
ganization of the first. There is then in this embryo
a new power, of organic essence, which modifies the
ordinary course of affinities, and impresses upon the
combinations present a special form, of which it is itself
the prototype.

The formation of the vegetable is not the only case
where foreign forces come thus to modify the ordinary
play of affinities. Mix hydrogen and nitrogen together
in the dark, there will be no combustion. Submit the
mixture to the action of the solar rays, an explosion
immediately takes place, and the gaseous mixture is
replaced by a new product —hydrochloric acid. Here
then are two elements incapable of entering into com-
bination by themselves, but which acquire this faculty
by the intervention of a foreign force —light. Min-
eral chemistry abounds in examples of this kind.

In the greater complication of vegetables under these
different relations, I consider it then to be correct not
to see a sufficient reason for believing that nature has

8

- traced a line of absolute demarcation between minerals
and vegetables, nor to admit that the laws of their for-
mation have nothing in common with those better known
laws which regulate the productions of the inorganic
kingdom. I think, on the contrary, that nature is
uniform in her general laws, and that by attentive ob-
servation aided by experiment, we may arrive at know-
_ing them in all their effects. I perceive then nothing
irrational in the attempt to arrive at the artificial reali-
zation of the conditions in which they are exercised to
produce vegetables, as science has already succeeded
in doing with minerals. This conclusion will acquire,
I hope, a stronger and stronger evidence as we pene-
trate deeper in our researches, and I shall at once give
a very striking confirmation of it, in showing you that
nature does not pass suddenly from the mineral to the
vegetable, from crude matter to organized matter, but
that there exists, on the contrary, a class of compounds
which lead us insensibly from the one to the other, and
form the bridge which unites these two series of pro-
ductions. These compounds which, for this reason, we
name transitory products of organic activity, range
themselves in two different groups — hydrates of car-
bon and albumenoids. The following is an enumera-
tion of them.

9

TRANSITORY PRODUCTS OF ORGANIC ACTIVITY.
Hydrates of Carbon, Albumenoids.

Cellulose jolt
Insoluble... | ark, ? \ Fibrine.

Gum Tragacanth,
Semi-Soluble < Mucilages, Caseine.

' Pectine,

Gum Arabic,
Soluble. . . .< Dextrine, Albumen.

Sugars,

Let us first examine the hydrates of carbon.

Considered separately, these bodies appear very un-
like each other.

Cellulose, which is the prime material of all vegeta-
ble tissues, is hard, insoluble in water, and resists the
action of most re-agents.

Starch presents itself in globules formed of concen-
tric layers. It swells and forms a jelly with boiling
water, or with a weak solution of potassa. Tincture of
iodine turns it blue.

Pectine also forms a jelly with water, but it exhibits
no trace of organization, and iodine does not turn it
blue.

Mucilages swell in cold water, but do not dissolve.

Gum Arabic dissolves in cold water.

Lastly, Sugars dissolve and crystallize, thus present-
ing one of the essential characteristics of mineral mat-
ters. )

Thus all these bodies form a regular series, of which
the types I have characterized are only distant terms.

10

But in nature we find all the intermediates by which
we can pass insensibly from each one to that which fol-
lows it. Itis thus that cellulose presents itself to us
under very different states of cohesion, from the wood
and perisperm of the date, where it is extremely hard,
unto the young shoots of all kinds of vegetables, and
the skins of fruits, where it is not more solid than
starch paste. The latter which in the apple, potato, and
wheat, is in solid globules, and isolated like grains of
sand, is found in a viscid state in other plants, and thus
passes gradually to the form of gums and mucilages.
Butween the latter and the sugars that crystallize, we
find the uncrystallizable sugars, Xe.

But the analogies which these bodies present with
each other do not stop here. It is, in fact, possible to
convert them artificially from one into another by the
very simple re-actions of the laboratory. Under the
influence of dilute acids and prolonged boiling, all are
resolved into grape sugar, which seems to be the least
organized form, the nearest to mineral nature that the
type can assume. As if to give a superior reason to
all these approximations, elementary analysis assigns
one and the same formula to all the compounds. Each
contains twelve equivalents of carbon united to the ele-
ments of water, and may be thus represented —

qa (HO
(Carbon.) ( Water.)

which entitles them to the denomination of hydrates of

carbon,

11

Beside this series of ternary compounds, we also
find in all vegetables, the albumenoids which, to the
three elements above indicated, join a fourth, nitrogen,
in an important quantity, and two others, sulphur and
phosphorus, in very small] proportions.

These compounds, much more complex than the first,
present themselves under three essential forms : insolu-
ble, semi-soluble, and soluble, to which the three types,
fibrine, caseine, and albumen respond. Like the pre-
ceding, they are met with in nature under very varied
conditions, and may be converted, one into another, by
the reactions of the laboratory.

The hydrates of carbon and the albumenoids form
then two parallel series, which exist side by side in the
substance of all vegetables, and which are constantly
undergoing the various transformations of which they
are susceptible.

Let. us show what takes place during the germination
of a grain of wheat. The hydrate of carbon exists in
the dried grain under the form of starch, and the albu-
menoid under the form of fibrine or gluten. In pro-
portion as the water penetrates the perisperm, it swells,
becomes milky, and then it contains albumen, and dex-
trine, and true gum. Subsequently, when the blade is
elongated, when the leaf begins to respire, you will find »
sugar and cellulose, which are produced at the expense
of the original starch. By the side of these bodies you
will find albumen derived from the gluten.

Let us examine on the other hand what takes place

12

during the formation of the seed. In beet-root, for ex-
ample, sugar exists. In proportion as the seed is formed
the sugar disappears, but on the other hand, the seed
is full of starch. During the foliaceous life of the plant,
its juice contains albumen; when the seed is formed,
the greater portion of the albumenized principle is found
concentrated in an insoluble form.

We are then fully justified in believing that these
bodies are being constantly transformed into each other
in the very substance of the vegetable, and that they
are like the several steps of a ladder, by which crude
matter gradually ascends to the rank of completely
organized matter.

But we have-seen that in the laboratory these trans-
formations are effected by energetic chemical agents.
What can be the cause which determines these same
effects in the substance of the plant ?

When sulphuric acid converts baryta into the sulphate
of that base, it combines with it, and there no longer
exists either baryta or sulphuric acid. The two con-
stituents are confounded in the product of the combi-
nation, which is sulphate of baryta.

When the same acid converts starch or cellulose into
sugar, things do not proceed exactly in the same man-
ner. After the transformation, we find the acid wholly
free. By its presence alone it acts like the solar ray
upon the mixture of chlorine and hydrogen: and sul-
phurie acid is not the only body which possesses this
property. The albumenoids, of which we have just

13

spoken, possess it in a higher degree, especially when
they have begun to undergo a change by contact with
the oxygen of the atmosphere.

Putrid gluten rapidly converts considerable quanti-
ties of starch into dextrine and sugar, and that without
being itself disturbed by the exercise of its own modi-
fications. The cause of the changes which the hydrates
of carbon undergo in the substance of vegetables resides
therefore in their encounter with the albumenoids, which
are themselves modified under the influence of water,
the oxygen.of the atmosphere, and the mineral agents
derived from the soil. ‘

We may then, finally, refer the greater part of the
work of vegetation to the reciprocal action of the
hydrates of carbon, albumenoids and minerals.

You perceive that all through this extremely com-
plicated chemical operation, we always encounter the
application of the general laws of chemistry, for the
actions of contact are not peculiar to vegetables. They
are also frequently encountered in the reactions which
are effected without organic agency, only they predom-
inate in the phenomena of vegetable life.

The study to which we devote ourselves therefore
warrants the parallel we have drawn between minerals
and plants, from the point of view of the superior laws
of their production. I shall conclude by confirming
this resemblance, and showing you that the separation
in the substance of the vegetable of the various elements
composing it, is submitted to a law as well determined,

14

T may say, almost as geometrical, as the arrangement of
the molecules in a crystallization.

Let us begin with the minerals. Considered as a
whole, they are more abundant in grasses than in trees.
The latter contains only 1 per 100 upon an average,
while grasses contain from 7 to 8 per 100.

The reason of this is very simple. In a salt marsh,
the quantity of salt deposited in summer is more con-
siderable than that produced in winter, because during
summer the temperature being higher, the evaporation
is more active. So also in vegetables, the quantity of
mineral matter they contain is great in proportion to
their evaporation. Now herbage being in contact with
the atmosphere in every part, it is the seat of an evapo-
ration much more active than that in trees, which con-
tain completely sheltered organs. We find a rigorous
application of this law in the tree. The sapwood con-
tains less mineral matter than the heart, the heart less
than the bark, the bark less than the leaves. In the
green leaves of trees there is less than in the leaves
that fall in autumn.

In leguminous plants, the pod is richer than the seed,
and in the seed there is more in the skin than in the
bean. The distribution of mineral matter in the sub-
stance of a vegetable obeys therefore an invariable law,
it is in direct relation with the activity of evaporation.
If we examine what takes place with regard to the
nature of the elements, we see that here also fixed laws
prevail. Phosphoric acid, potassa, and magnesia pre-

15

vail in the seeds, the alkaline earths and iron on the
contrary prevail in the stalks.

The alkalies increase in proportion as we approach the
fruit and young shoots. They are much less abundant
in those organs which are oid and have less vital activity.

Phosphoric acid is disseminated in a nearly uniform
manner throughout the vegetable, and suddenly increases
when it arrives at seeding.

‘As to the organic elements, the laws are no less pre-
cise. Carbon, oxygen, and hydrogen, which, in the
state of hydrates of carbon, form the general framework,
are found diffused nearly uniformly throughout all the
organs. Nitrogen, which forms an essential portion of
the albumenoids, of which the most important part con-
sists in the active task of the formation of the tissues,
is found in the greatest quantity in all the recent shoots,
and especially in the seed, the last product of annual
vegetable activity.

We have arrived in this lecture at defining vegeta-
bles as material combinations of an order superior to
mineral combinations, but like them, dependent upon
the association of the first elements under the influence
of the general laws of chemistry. This definition leads
us invincibly to the hope of producing them artificially,
and in every part, by means of their elements placed
at our disposal, under conditions where they are suscep-
tible of assuming this kind of combination. It remains
for us to examine the means we can employ to attain
this aim.

+) it ne baa Wry 4 Me aa La

gre

ANALYSIS.

THE ORGANIC ELEMENTS OF VEGETABLES ARE OXYGEN, HYDRO-
GEN, CARBON, AND NITROGEN. — UNDER WHAT INFLUENCES AND
CONDITIONS THESE ELEMENTS ENTER THE VEGETABLE FROM WITH-
OUT. —CARBON ENTERS THE PLANT UNDER THE FORM OF CARBONIC
ACID, WHICH IS ABSORBED BY THE ROOTS, AND BY GREEN LEAVES
UNDER THE INFLUENCE OF SOLAR LIGHT, AND EMITTED FROM THE
LEAVES DURING DARKNESS.— OXYGEN IS DISENGAGED FROM THE
LEAVESIN EXACT PROPORTION TO THE QUANTITY OF CARBONIC ACID
ABSORBED, — WHAT BECOMES OF THE CARBONIC ACID ABSORBED ? —
IT IS DECOMPOSED, ITS CARBON FIXES ITSELF IN THE VEGETABLE
WHILE ITS OXYGEN IS REMOVED. — UNLIMITED SUPPLY OF CARBONIC
ACID FROM THE RESPIRATION OF ANIMALS, FROM THE FORMATION OF
PYRITES, AND FROM VOLCANOES.—CARBON FORMS ABOUT 50 PER
CENT. OF DRIED PLANTS—THE QUANTITY FIXED DEPENDS UPON
THE EXTENT OF THEIR FOLIAGE.— WATER THE SOURCE OF THE
OXYGEN AND HYDROGEN IN PLANTS; IS SOMETIMES DECOMPOSED,
LIKE CARBONIC ACID, THAT ITS OXYGEN MAY BE ELIMINATED. —
PLANTS CONTAIN ONLY SMALL QUANTITIES OF NITROGEN, BUT IT IS
AN INDISPENSABLE ELEMENT, — THEY CONTAIN MUCH MORE NITRO-
GEN THAN IS SUPPLIED BY MANURE— WHICH EXCESS IS OBTAINED
FROM THE ATMOSPHERE. — THE NITRATES OCCUPY THE FIRST RANK
AMONG THE NITROGENOUS MATTERS USEFUL TO VEGETATION. —
NEXT COME AMMONIACAL SALTS.—SOME CROPS DO NOT REQUIRE
THE ADDITION OF NITROGEN TO THE SOIL.— THE CEREALS REQUIRE
THIS ADDITION IN LARGE QUANTITIES.
17

LECTURE SECOND.

In our first discourse we arrived at the consideration
of the vegetable as a material aggregate, having the
closest analogy with chemical combinations. We have
seen that the laws which preside at its formation differ
in no respect, in a philosophical point of view, from
those which regulate the production of the compounds
of mineral chemistry.

If it be so, in order to penetrate the mysteries of the
production of vegetables, the first thing we have to do
is to ascend to the origin of their elements, and after-
wards inquire in what conditions, and under what
influences, these elements enter from without, and com-
bine together in a special manner to produce the vege-
table. |

Let us commence this study with the organic ele-
ments, which are:

Carbon. Oxygen.
Hydrogen. Nitrogen.

The carbon cannot penetrate vegetables, except under
18

19

the form of carbonic acid. This gas arrives by two
different ways.

ist. By the roots, which draw it from the soil, where
it is produced by the spontaneous decomposition of
organic matters.

21. By the leaves, which take it from the atmos-
pheric air, where it exists permanently.

In order for the carbonic acid to be absorbed, it is
necessary that four essential conditions be realized.

The first is of organic nature, and resides in the
green color of the organs of vegetables. The petals
of flowers which are variously colored do not absorb
carbonic acid: the leaves, the bark, and the pericarp
of green fruits, on the contrary, absorb it in abun-
dance. In the generalization of this fact it may be
objected that purple leaves, and leaves that are almost
white, exist, which also absorb carbonic acid from the
air. I find the reply ia a recent work by M. Cloez.
This chemist has shown that the leaves referred to, not-
withstanding their different aspect, contain large quan-
tities of green matter. It is, then, safe to say that the
function under consideration depends upon this green
matter.

Whatever the color of the organs, carbonic acid is
never absorbed in the absence of solar light. This
second external condition of the vegetable is also as
indispensable as the first. Would you wish to prove
it? Pass a current of air into a large receiver contain-
ing a young vine with its leaves, and connected with an

apparatus capable of measuring carbonic acid. You
will perceive, as M. Boussingault has done, that in the
sun, the atmospheric air, in passing over the green
leaves, loses nearly one-half its carbonic acid, while in
the dark, on the contrary, it gains a very considerable
quantity. Not only, then, the leaves absorb no car-
bonie acid in the dark, but they also constantly emit it,
to the destruction of a portion of their substance.
When the leaves are attached to the plant, they disen-
gage more carbonic acid than when they are removed,
because that which the roots derive from the soil, not
being decomposed in the vegetable, comes then to be
exhaled from the surface of the leaves.

A third indispensable condition, also, is the interven-
tion of a certain temperature. MM. Gratiolet and
Clocz have shown that the leaves of the potamogéton,
which, in water at 54° E., disengages abundance of
oxygen, ceases to do so ahah the temperature is low- _
ered to 387° I’. Now, as we shall soon see, this disen-
gagement of oxygen is precisely the certain index of
the absorption of carbonic acid.

Finally, the fourth and last condition of the pheno-
menon is the presence of oxygen in the atmosphere in
which the leaves are placed. Theodore de Saussure
has proved that in an atmosphere of hydrogen or nitro-
gen, containing carbonic acid, this gas is not absorbed
by plants. On the contrary, the phenomenon manifests
itself whenever oxygen forms a portion of the surround- -
ing gases.

21

What becomes of the carbonic acid thus absorbed
by plants? While this substance resists the highest
temperatures and the most powerful chemical reducing
agents, in the substance of plants this acid is decom-
posed, its carbon fixes itself in the vegetable, and its
oxygen is removed. Hence the disengagement of
oxygen which takes place on the surface of leaves
immersed in water. ‘This fact, one of the most impor-
tant which science has discovered in this century, has
been brought to light by the labors of a whole gener-
ation of savants, but it was principally by Theodore de
Saussure that the conditions were defined. THe saw
that the quantity of oxygen emitted was equal in vol-
ume to the carponic acid absorbed, and that minute
quantities of nitrogen were disengaged. This disen-
gagement of nitrogen, since proved by MM. Gratiolet
and Cloez, has recently been denied by M. Boussin-
gault.

Not wishing to insist upon this point, which has no
interest in agriculture, I shall merely remark that, in
all the experiments made, one condition, which could
alone give value to their results, has been wanting.
For it to be legitimate, in fact, to extend to vegetation
the facts observed in these experiments, they must be
performed upon vegetables in progress of development,
constantly increasing in weight, and not upon detached
portions, which may, it is true, still give vital manifes-
tations, but the ephemeral existence of which is neces-
sarily accompanied by special phenomena of destruc-
tion.

22

The assimilation of the carbon, so interesting in a
physiological point of view, presents only an insignifi-
cant interest for agriculture: there need be no fear of
its ever failing, for the atmosphere contains an unlimited
supply of it. In proportion as vegetation appropriates
it, animal respiration, by an inverse effect, restores it
in equivalent quantities. This harmony between the
two organic kingdoms, first observed by Priestley, and
so brilliantly explained by Dumas in his Statistics of
Organized Beings, is nevertheless only an infinitely
small one among the causes of the permanence of the
atmospherie carbonic acid.

Among geological phenomena, causes of loss exist
which are much more powerful than vegetable absorp-
tion. The disintegration of felspars removes colossal
quantities of this acid from the air, but voleanoes and
the formation of pyrites constantly restore it in quan-
tities no less important, so that its composition presents,
under this relation, quite a satisfactory stability for
agriculture.

Carbon enters into the composition of all plants in
the proportion of about 59 per 100, when they are
dried. It is to this element that the variation in the
weight of crops is due. The quantity plants assimilate
depends, in great measure, upon the surface of their
leaves, and also a little upon their special nature.
Experiment has proved that plants which, upon an
equal surface of ground, fixed most carbon, were those
that presented the greatest foliaceous surface. We

23

have seen, also, that with an equal surface of leaves,
plants fix quantities of carbon differing a little accord-
ing to the species.

The oxygen .and hydrogen found in vegetables are
undoubtedly derived from water; this latter may he
assimilated naturally, as is proved by the existence of
hydrates of carbon in the substance cf vegetables in
which oxygen and hydrogen are found in the propor-
tions necessary to form water. But the formation of
resins, essential oils, and fat bodies, in which hydrogen
predominates, shows that in certain cases, water may
be reduced, like carbonic acid, and that its oxygen may
be eliminated. Whatever it be, the origin of the oxygen
and hydrogen once established, we have no need to dwell
on this point, for the plants, not being deficient of water,
are in consequence abundantly provided with these two
elements.

It is not the same with nitrogen. Plants contain it
only in relatively very small quantities, but they have
an indispensable need of it, and as in certain cases it
may fail, it is necessary to study with the greatest care
every thing that concerns the assimilation of this ele-
ment.

First let us show that all plants exhibit in the crops
a much greater proportion of nitrogen than there was
in the manure supplied to them. The following data
taken from “ Boussingault’s Rural Economy ” establish
this fact.

24

Plants. Annual Excess of
Nitrogen per Acre.
Potatoes
W heat
Rotations of Cis: lbs.
Five years. Worn 8:36
[ Oats
Beach
Forest culture { Oak 29-04
irch
| Poplar
Exclusive culture Artichokes 37°84
Exclusive culture Luzerne 182:06

If the crops contain such quantities of nitrogen of
which the soil can render no account, we must look to
the atmosphere as its origin. ‘The air contains 79 per
100 of elementary nitrogen: nothing appears more
rational than to find there the origin sought. But
chemists, accustomed to see nitrogen gas offer a great
resistance to combination, have at first preferred to re-
fuse to it all intervention in the phenomena of vegeta-
tion. ‘To restore it to the place which this preconceived
opinion, or one founded upon incomplete experiments,
had caused it to lose, it was necessary to have recourse
to extremely delicate experiments, which it is impossible
to describe in this place.

I shall therefore content myself with refuting, by
arguments derived from extensive cultivation, all the
origins which the adversaries of the absorption of
gaseous nitrogen are compelled to put forth, referring

25

to my works and to my lectures at the Musewm those
amongst you who desire to know the direct proofs of
this absorption.

Priestley and Ingenhouz believed in the assimilation
of the elementary nitrogen of the atmosphere. Theo-
dore de Saussure having proved the existence of ammo-
nia in the air, attributed to this compound the faculty
of supplying nitrogen to vegetables. Ammonia does
in fact exist in the atmosphere, but the quantity is so
small (22 grammes in 1 million kilogrammes), that it
is evidently absurd to endeavor to make it play so im-
portant a part.

The objection has also taken another form. It is
urged that the air contains ammonia Rain water dis-
solves it, condenses it, and conveys it to the plant,
which thus finds it in the soil. If in the place of thus
contenting themselves with this vague assertion, they
had thought to give it precision by measuring the am-
monia in the rain water, and ascertaining the quantity
of this water received per acre, they would have found
by this way, that the soil receives, as a maximum, about
3 pounds of nitrogen per annum. But to explain the
vegetation of luzerne we must account for 182 pounds
of nitrogen. The ammonia in rain water is then only
infinitely small in relation to the phenomenon under
consideration.

Ammonia failing, recourse was had to nitric acid,
which is formed in the atmosphere by the direct com-
bination of oxygen and nitrogen under the influence of

~

26

electric discharges and during rain storms. And anal-
ogous calculations to the preceding show that, by this
new way also, 1 acre of land receives 38 pounds of
nitrogen, at the most. Nitric acid therefore explains
no better than ammonia the excess of nitrogen in the
crops.

But, it is urged, there may exist in the atmosphere
some nitrogenous substance eminently assimilable,
which is condensed by rain water, and which has hith-
erto escaped analysis. Notwithstanding the utter
vagueness of this objection, I have wished to reply to
it by direct experiment. I have instituted two similar
growths in boxes placed under shelter; one of them
was watered with rain water collected by a pluviometer
of equal surface to that of the box, and placed apart:
the other received similar quantities of perfectly pure
distilled water. The crop with distilled water was
nearly as large as that obtained with rain water. It is
therefore evident that rain water contained nothing
susceptible of influencing the development of vegeta-
bles.

But, since it has been desired to give this importance
to the essential products the air may yield to the soil,
it will be permitted to me, on the other hand, to con-
sider those which the soil yields to the atmosphere ;
and this time it is from my adversaries themselves that
I borrow the bases of my arguments.

M. Boussingault had the idea of collecting the snow
from the surface of the ground and the terrace of a

27

garden. A litre of water from the first contained
0-0017 gr. of nitrogen, while that from the terrace
contained 0-0103 gr. It is certain, therefore, that eul-
tivated soil constantly loses nitrogen. if we suppose
that the layer of snow examined by M. Boussingauli
had a thickness of only 6-01 m. it contained in 1 acre,
180 pounds of nitrogen lost to the soil. We sec, then,
that the losses the soil is capable of experiencing are
quite as important as the gains it may derive from the
atmosphere. We must necessarily, then, have recourse
to elementary nitrogen to explain the excess in the
crops.

But, here another subject of discussion presents
itself ; the nitrogen of the air — is it absorbed naturally
by plants, as [ have always maintained, or does it take
place, as recently suggested, only by the intermedium
of nitrification previously accomplished in the soil,
which would thus be a real artificial nitre-bed ? Doubt-
less, in certain cases, important quantities of nitrates
may be produced in the soil; but I none the less per-
sist In saying that nitrification cannot account for the
excess of nitrogen in the crops. For the 182 pounds
to have penetrated into the luzerne by this channel, it
would have been necessary to engage 1756 pounds of
nitric acid which, itself, to be saturated, must have
combined with 1540 pounds of bases. These 1540
pounds of bases should be found in the crops: but, the
latter produced upon combustion, only 1525 pounds of
ashes, of which the bases formed 701 pounds. There

€

28

is, then, at least half the excess that the hypothesis of a
nitrification cannot explain.

Besides, if it were so, if the nitrogen of the crops
came from the nitrogen formed in the soil, is it not
evident that an artificial addition of nitrates would pros
duce the same effect as a natural formation ?

Now there exists, in fact, some crops, that of wheat,
for example, the addition of nitrates to which increases
the yield. But there are others, as you may see for
yourselves by inspecting the experimental field, upon
which nitrates exercise no influence. Peas for example,
have not assimilated more nitrogen with a strong manure
of nitrates than without the addition of any nitroge-
nous compound. It is then quite evident that if, in cer-
tain cases, natural nitrification can play a definite part,
it may, on the other hand, serve as a general explana-
tion of the excess of nitrogen in the crops, and that the
true and great origin of this nitrogen resides in the
atmospheric nitrogen directly absorbed.

And moreover, what is there, in a theoretical point
of view, so repugnant to the admission of this absorp-
tion? Aswe speak of nitrification in the soil, who can
deny that in the substance of leaves, where nitrogen
undoubtedly penetrates, where it constantly meets with
nascent oxygen, ozonised — the formation of nitric acid
must be at least as easy as it is in thegoil? And when
we perceive these organs endowed with a chemical power
sufficient to reduce carbonic acid, is it then inconceiva-
ble that they are capable of causing nitrogen to enter

>

29

into combination more readily than it does in our labor-
atories? No! the absorption of nitrogen, proved by
experiment, is not irrational, and it is only habit and
prejudices that oppose this doctrine, which, alone, is
susceptible of giving us the clue to the phenomena of
vegetation, and reacting usefully upon agricultural prac-
tice. |

If the nitrogen of the air can contribute to vegeta-
ble nutrition, is it to be said that we are not to trouble
ourselves about supplying nitrogen to our crops, and
that with regard to this element we find ourselves in
the same state of security and weakness as with the
first three that occupied our attention? Doubtless no!
Practice on a large scale has proved the utility of nitro-
genous manures, and I have myself proved that the
yield of the cereals is considerably increased by the
introduction of nitrogenous material into the soil.

Of all the substances I have tried, the nitrates have
always given me the best results, when I have operated _
on a small scale, and when the quantity of nitrogen
supplied to the crops was inferior to that which the
_yield should have contained. On the large scale, M.
Kuhlmann has obtained similar results. But at the
experimental farm, at Vincennes, I have observed no
difference between the employment of nitrates and of
ammonial salts. This is due, doubtless, to the manures
I had recourse to, and which I intended for several
successive years, having been supplied in very large

ay)

quantities, and that the plants, always finding in the
soil an excess of assimilable nitrogen, prospered as well
in one case as in the other.

Therefore I do not hesitate to say that I place the
nitrates in the first rank among nitrogenous matters
useful to vegetation. Next come ammoniacal salts, and,
a long way after them, organic nitrogenous matters,
which, to act usefully, must be previously converted
into nitrates or ammoniacal salts.

All that we have said concerning nitrogen may be
summed up in the following conclusions, the agricul-
tural importance of which cannot be questioned.

1. Generally speaking, the nitrogen of the air enters
into the nutrition of plants.

2. In connection with certain crops, especially vege-
tables, this intervention is sufficient, and the agricul-
turist has no occasion to introduce nitrogen into the
soil,

3. With regard to the cereals, and particularly dur-
ing their early growth, atmospheric nitrogen is insufh-
cient, and to obtain abundant crops it is necessary to
add nitrogenous matters to the soil. Those which best
fulfil this object are the nitrates and ammoniacal salts.

ANALYSIS.

ON THE ASSIMILATION OF MINERAL ELEMENTS WHICH PENETRATE
THE PLANT IN AQUEOUS SOLUTION ONLY.—THE MEDIUM FROM
WHENCE THE ROOTS OBTAIN THEM.— THE SOIL IS THE SUPPORT OF
THE ROOTS, THE RECIPIENT OF THE SOLUTION THAT FEEDS THEM,
AND THE LABORATORY WHERE THIS SOLUTION IS PREPARED: IT IS
COMPOSED ESSENTIALLY OF THREE CONSTITUENTS —HUMUS, CLAY,
AND SAND.— PROPERTIES OF HUMUS: ITS INFLUENCE IN THE SOIL,
FIXES THE AMMONIA—IiS A CONSTANT SOURCE OF CARBONIC ACID
WHICH DISSOLVES THE MINERAL MATTERS, AND IS THE PRINCIPAL
AGENT IN SUPPLYING PLANTS WITH THEIR MINERAL CONSTITUENTS.
— UTILITY OF CLAY IN ARABLE LAND —IMPARTS CONSISTENCE TO
THE SOIL, RETARDS THE PASSAGE OF WATER, FIXES AMMONIA, AND
REMOVES A LARGE QUANTITY OF SALTS FROM SALINE SOLUTIONS,
STORING THEM UP FOR FUTURE SUPPLY.— ESTABLISHES AN EQUI-
LIBRIUM BETWEEN SEASONS OF DROUGHT AND RAINY WEATHER. —
SAND FORMS PART OF EVERY SOIL; FORMS ITS PRINCIPAL CONSTITU-
ENT, COMMUNICATING TO IT ITS PRINCIPAL PHYSICAL PROPERTIES.
ESPECIALLY ITS PERMEABILITY TO AIR AND RAIN WATER—IT TEM-
PERS THE PROPERTIES OF CLAY.— ELEMENTS OF THE SOIL, WITH-
OUT WHICH VEGETABLE LIFE IS IMPOSSIBLE: PHOSPHATE OF LIME,
POTASSA AND LIME, WHICH ASSOCIATED WITH A NITROGENOUS SUB-
STANCE, AND ADDED TO ANY KIND OF SOIL, SUFFICE TO RENDER IT
FERTILE. — CHEMICAL ANALYSIS FAILS WHEN APPLIED TO SOILS —
NECESSITY FOR SUBSTITUTING AN ARTIFICIAL KNOWN COMPOUND
IN EXPERIMENT, TO REMOVE ALL SOURCE OF ERROR.— RESULTS
OBTAINED—1, WITH CAILCINED SAND ALONE. 2. WITH CALCINED
SAND, AND NITROGENOUS SUBSTANCES. 3. WITH CALCINED SAND AND
MINERAL SUBSTANCES. — EACH AGENT OF VEGETABLE PRODUCTION
EXERCISES A DOUBLE FUNCTION. 1. AN INDIVIDUAL FUNCTION
VARIABLE ACCORDING TO ITS NATURE. 2. A FUNCTION OF UNION. —
SPECIAL ACTION OF NITROGENOUS MATTER AND MINERAL SUB-
STANCES, — RESULTS, —A SOIL CAPABLE OF PRODUCING PLANTS, MUST
CONTAIN IN AN ASSIMILABLE FORM, NITROGENEOUS MATTER, PHOS-
PHATE OF LIME, POTASSA, AND LIME.—ERRORS COMMITTED IN
APPLYING MANURE TO SOILS THE COMPOSITION OF WHICH IS UN-
KNOWN.— THE SOURCE OF ERROR REMOVED BY THE EXPERIMENTS
NOW DESCRIBED. — PROSPECT OPENED BY SCIENCE TO AGRICULTURE.
31

LECTURE. THIRD.

THE logical order of our inquiries conducts us imme-
diately after the assimilation of the organic elements
treated of in our last lecture, to the same question in
respect to the mineral elements. But these bodies
penetrate the vegetable only under the form of aqueous
solution, and before showing you the effects they pro-
duce, when absorbed, it is necessary that [ should make
known to you the medium from whence the roots derive
them.

The soilis, at the same time, the support of the roots,
the recipient of the solution that feeds them, and the
laboratory where this solution is prepared. It is com-
posed essentially of three constituents, which concur,
each in a certain proportion, to give to the whole the
properties which I proceed to enumerate. They are
humus, clay, and sand.

Humus is of organic origin. It possesses a deep
brown color, almost black. It is the cause of the dark
color of vegetable mould. It dissolves in alkalies, with
which it produces an almost black liquor. Acids sep-

arate it from this solution under the form of a light,
32

33

flocculent precipitate of a deep brown color. While it
remains moist it will dissolve slightly in water, but
when once it is dried it will no longer dissolve in it.
It does not crystallize; and under the action of heat
it is decomposed, leaving a carbonaceous residue.

Such are the properties which chemists assign to
humus, but there is nothing very characteristic, noth-
ing to show that humus is of a very definite chemical
species. In fact, chemistry experiences the greatest
difficulties whenever it attempts to specify a body which
does not crystallize, and which is not volatile. For in
that case we can proceed only by way of induction.
This is what we shall attempt to do in order to arrive
at a clear idea of the constitution of humus.

If we submit to the controlled action of heat the
kydrates of carbon described in our first lecture, sugar
for example, it will not be long before we produce a
brown body which is designated by the name of cara-
mel. The chemical composition of this caramel is
nearly the same as that of the sugar from whence it is
derived, showing that the only difference existing he-
tween them consists in the loss experienced by the
sugar of a certain quantity of water. Sugar being
represented by the formula C¥ H” O” or C¥ (IIO)®,
caramel is expressed by C” (HO)®, When we act
upon sugar with hot baryta water, we obtain another
brown body, apoglucic acid or assamare, containing still
less water than caramel. By the action of an excess

of alkali upon sugar we descend to melassic acid, which
‘3

o4

always contains hydrogen and oxygen in the propor-
tions necessary to form water, but in still less quantity
than the preceding bodies.

It is then possible, by the reactions of the se lahomici
to remove successively from the hydrates of carbon,
and, as it were, molecule by molecule, the greater part
of the water that enters into their composition, without
their departing in consequence, from the original type,
as in these various products the carbon always remains
associated with the elements of water, and all may be
represented by the general formula of hydrates of car-
bon C? (HO)?.

Now this gradual decomposition of the hydrates of
carbon goes on incessantly in arable land, where vege-
table debris of all kinds is buried.

Humus is nothing more than the ordinary limit of
this decomposition. Some chemists assign to it the
formula C” H® O°; but it is rather a collection of every
kind through which the progressive decomposition of
the hydrates of carbon passes, and I have no doubt
that we can go much beyond the formula expressed by
O* (HO. Coal, studied from this point of view, fur-
nishes us with valuable instruction.

Death thus realizes a series of phenomena exactly
the reverse of those produced in the substance of liy-
ing vegetables. For while, among these latter the car-
bon, reduced from carbonic acid, fixes upon the elements
of water in greater or lesser proportion to produce all
the hydrates of carbon, — in the soil, on the contrary,

35

the water separates little by little from the carbon to
arrive finally at leaving it almost in a state of liberty.

If the chemical properties of humus are difficult to
characterize, its presence in the soil is none the less
useful to agriculture. It absorbs water with great
energy, and greatly increases in volume under its influ-
ence. By this property it contributes to maintain the
coolness of the soil by retarding its drying.

When humus is put in contact with an ammoniacal
solution, it removes the ammonia from it, hut retains
it only by a very feeble affinity, for it is only pn cessary
to introduce a large quantity of water to recover it.
Iiowever, it does not fix combined ammonia; that is to
say, when it is combined in ammoniacal salis. Mixed
with carbonate of lime or marl, does it acquire the
faculty of fixing ammoniacal salts also?

By this manner of comporting itself with ammonia
and ammoniacal salts, the utility of which are recog-
nized in our previous lecture, humus renders important
services to vegetation. It prevents, at least partially,
the loss of the ammonia which results from the spon-
taneous decomposition of nitrogenous organic matters
buried in the soil.

Moist humus, exposed to the air, undergoes a slow
combustion which makes of it a constant source of
carbonic acid. The part played by this acid in vegeta-
ble nutrition is of the highest importance, as was
shown in the preceding lecture: still the small quantity
produced by the decomposition of humus can searcely,

36

by its direct absorption, favor the development of plants
which otherwise find it abundantly in the atmosphere.
Besides, we do not attach very great importance to the
humus under this relation. But the carbonie acid
which it unceasingly produces in the soil fulfils another
function, incomparably more useful. It serves to dis-
solve the mineral matters, phosphates, alkalies, lime,
magnesia, iron, etc. It causes the disaggregation of
fragments of rocks containing useful matters which
water alone cannot attack, and which, without it, would
remain inert in the soil. Carbonic acid derived from
humus is then, as a whele, the principal agent of solu-
tion capable of suppiying plants with their mineral ali-
ment.

Clay intervenes no more directly than humus in veg-
etable nutrition. Nevertheless, its presence in arable
land is of unquestionable utility. Clay is a hydrated
silicate of alumina, retaining its water with great per-
sistence, forming with it a very plastic paste, which
serves to fabricate pottery. Its presence in the soil
imparts consistence to it, diminishes its permeability,
and maintains its coolness by retarding the passage of
water. Like humus, clay fixes ammonia by a kind of
capillary affinity, but it also possesses this property with
regard to all saline solutions. By its agency the solu-
ble salts resist flowing waters; still more, it removes
from highly charged saline solutions a much larger
quantity of salts, and yields them up again to the water
when it arrives in sufficient quantity. In a very fertile

o7

soil, that is to say, one much charged with soluble salts,
when little water is present, the solution it produces
might attain to such a degree of concentration as to
pecome injurious to plants.

In this case, the clay, by appropriating the greater
part of the salts, sufficiently weakens the solution. If,
on the contrary, abundant rain falls, the clay gives up
what it had previously taken, and thus re-establishes
the equilibrium between seasons of drought and rainy
weather,

In these circumstances, the clay acts as a sort of
automatic granary, which, out of its abundance, stores
up superfluous aliments to distribute them again when
scarcity prevails. It regulates the strength of the ali-
mentary solution, as the fly-wheel of a steam engine
regulates its motion,

As for the sand, it forms part of all soils, of which
it is the essential constituent. It communicates to the
soil its principal physical properties, and its permea-
bility to air and waier. It tempers the properties of
the clay, and by its association with it, realizes the con-
dition most favorable to the development of plants.

We have studied the inert elements of the soil, those
which enter into its composition to at least 99 per 100,
but which, nevertheless, concur in vegetable production
only by their physical properties. It now remains for
us to examine the elements which exist in but very
slight proportions in the soil, but of which the part
played is capital in the life of plants, since without
them vegetation is impossible,

38

Here, as with the organic elements, we commence by
removing from the discussion the principles which are
found in sufficient quantity in all soils, and of which,
consequently, agriculture has no need to concern itself.
For this reason we pass by in silence, silica, magnesia, iron,
manganese, chlorine, and sulphuric acid. Phosphate cf
lime, potassa and lime remain. These are the essential
minerals, such as, associated witha nitrogenous substance
and added to any kind of soil, suffice to render it fertile.
With them we can actually fabricate plants.

At the commencement of my experiments, fifteen
years ago, struck with the weakness of the old chemists
with regard to the problems raised by vegetation, a
weakness which { shall account for in my next lecture,
I decided upon attempting a new method. The soil
could not be known with accuracy, for chemical analy-
- sis had completely failed in ascertaining its composition.
I resolved to substitute for it an artificial mixture, all
the elements of which were clearly defined. In this way
I arrived at producing vegetation, in pots of china bis-
cuit, with calcined sand and perfectly pure chemical
products.

In these ideal conditions I instituted the four follow-
ing experiments : —

1. Calcined sand alone.

2. Calcined sand with the addition of a nitrogenous
ail

. Caleined sand with minerals only (pheephate of
ae potassa and lime).

39

4, Calcined sand with the minerals and a nitrogen-
ous substance. |

I sowed on the same day, in each pot, 20 grains of
the same wheat, weighing the same weight, and kept
the soils moist with distilled water during the entire
duration of vegetation. At the harvest I observed the
following facts.

In the sand alone the plant was very feeble; the
crop dried weighed only 93 grains.

In the nitrogenous substance alone, the crop, still
very poor, was however better ; it rose to 140 grains.

In the mineral alone, it was a little inferior to the
preceding ; it weighed 123 grains.

But with the addition of the minerals and the nitro-
genous substance, it rose to 870 grains.

Irom this first series of experiments we conclude
that each of the agents of vegetable production fulfils
a double function :

1. An individual function variable according to its
nature, since the nitrogenous matter produces more
effect than the minerals, and as either, employed separ-
ately, raises the yield above what the seed could pro-
duce by itself in pure sand.

2. A function of union, since the combined effect of
the nitrogenous substance and the minerals is very su-
perior to what each of these two agents produces sep-
arately.

But it is not sufficient to prove the relation of de-
pendence which exists between the action of the nitro-

40

genous matter and the minerals, taken en masse ; we
must take account of the special action of each of them.
Let us then institute new experiments, in which we
associate variable mineral mixtures with a nitrogenous
substance, always the same, and employed in the name
quantity.

Let us commence by suppressing, among the miner-
als first employed, the phosphate of lime, and in its
stead associate, with the nitrogenous matter, a mixture
composed only of Lime and potassa.

In these new conditions, vegetation is not possible.
The seeds germinated and scarcely arrived at 4 inches
in height; the plants withered and died. A mixture
of potassa and lime is therefore injurious to vegetation.
To make it useful, phosphate of lime must be added.
Do you wish to prove it? Make a fresh experiment
with the same agents and a trace of phosphate of lime,
0.01 grains in 1000 grains of soil, and you will obtain a
plant — meagre, it is true — but which does not wither
and die. When the phosphate of lime is in sufficient
quantity, the crop rises to 870 grains, as before stated.

There exists, then, between the phosphate of lime
on the one part and the potassa and lime on the other,
a relation of unity analogous to that which we have
shown to exist between nitrogenous matter and miner-
als.

To render an account of the part played by potassa,
let us make a fresh experiment, from which we will
bamish this alkali, and in which, consequently, the soil

41

will be fertilized with the nitrogenous matter and a mix-
ture of lime, and phosphate of lime.

Here the plant does not die, but the crop is inferior
to that given by nitrogenous matter alone; it descends
to 128 grains. Potassa is then an indispensable ele-
ment, in a less degree however than phosphate of lime,
since its absence does not, as with the preceding, cause
the death of the plants.

Seeing that soda replaces potassa in most industrial
uses, we inquire if it might not do the same with re-
spect to vegetation. Hxperiment has defeated this hope.
In the absence of potassa, soda exercises no influence
upon the yield, which remains just the same, whether
it intervenes or not. It is then indisputable that, with
regard to wheat, potassa is of the first necessity, and
that soda cannot be substituted for it.

It remains to explain the part played by lime. Here
the question becomes much more complicated. The
method we employed just now, and in which we made
only pure and artificial products to enter, leads us to
results of little importance only.

An experiment made with nitrogenous matter, phos-
phate of lime, and potassa only, gave a crop of 340
grains, while we obtain 370 grains with the complete
mamire, by which I understand — the mixture of nitro-
genous matter and the three essential minerals : phos-
phate of lime, potassa and lime. This slight difference
seems to indicate that lime plays only a secondary part.
Nevertheless, agricultural practice obtains very good

42

effects from it. We must then seek by other ways to
discover what may be the nature of its action.

If we substitute a mixture of sand and humus, for
pure sand without lime, the yield remains, like the
preceding, equal to 349 grains. In the absence of
lime, the humus has, then, no action, either useful or
injurious. But if we add lime (in the state of carbon-
ate) in this same experiment, the yield immediately
rises to 493 grains. The lime which, in the absence
of all organic matter, influences the yield in but an
insignificant manner, manifests, on the contrary, a very
decisive action in the presence of humus, which produ-
ces no effect of itself, when alone.

There exists, then, between lime and humus a remark-
able relation of unity. All the experiments lead us to
this final conclusion : that the soil, to produce plants,
must contain, under an assimilable form, a nitrogenous
matter, with phosphate of lime, potassa and lime, and
that to insure the efficacy of this latter, the presence of
humus is indispensable. You will now comprehend,
without difficulty, why agricultural experiments made
upon soils more or less fertile have not led, and cannot
lead, to any general practical conclusion.

Suppose that an agriculturist had the idea of adding
to a field abounding with phosphate of lime, a manure
containing a mixture of nitrogenous matter, potassa and
lime, he will obtain a magnificant harvest, — because the
phosphate of lime in the soil united to the matters
brought by the manure, will complete the latter, and

43

a

the plants will find every thing necessary to secure their
development.

This agriculturist will sound the praises of his ma-
nure. Others, imitating his example, will try the same
experiment. Butif it happens that their fields contain
no phosphate of lime, far from yielding the marvellous
results promised, this manure will, on the contrary,
lower the yield, for we now know that in the absence
of phosphate of lime, a mixture of nitrogenous matter,
potassa, and lime, is injurious to vegetation.

This example will, l think, suffice to explain all the
mistakes that cultivators have experienced in the course
of agricultural experiments, and to justify my method,
which consists of removing every thing unknown from
the soil, by substituting for the latter an artificial mix-
ture of definite-composition.

Now that by delicate and precise experiments we have
arrived at the knowledge of the superior laws of the
production of vegetables, shall we remain contented
with philosophicaily contemplating them, and continue
to follow, as before, a blind empirical practice? Shall
we continue without concern to exhaust the soil around
us, and restore to it, in the form of manure, only a
small portion of what it yields to us in the form of
crops, ready to transfer our industry elsewhere, when
our country refuses to nourish us, as the Arab transfers
his tent and his flocks? Or shall we continue, in de-
spair of the cause, to surrender ourselves blindfolded
to the charlatanism of adulterated manures and the

44

¥

traders in an agricultural panacea? No! these truths,
so simple and so fruitful, will quit our laboratories to
enter into daily practice. Our industry will seek the
elements of fertility in the vast quarries where nature
has stored them up, and agriculture, henceforth, confi-
cent in itself and its products, will assume greater
attractions, and come to range itself, like all other
branches of production, under the essentially progres-
ive banner of supply and demand.

Such is the prospect opened by science to agriculture,
and which it remains for us to sound the depths. But
before attempting, with reference to arable land, the *
problem we propose to solve under ideal conditions, we
must study the soil itself, and learn how to ascertain its
elements of fertility, in a word, to analyze it. In my
next lecture I shall explain to you why chemists have
failed, and shall show you how, more fortunate than my
predecessors, I have arrived at success myself.

ANALYSIS.

SCIENCE CHIEFLY CONCERNS ITSELF WITH THE ELEMENTS OF
BODIES AS MODIFIED BY ASSOCIATION, AND THE VARIOUS FORMS OF
WHICH THIS ASSOCIATION IS SUSCEPTIBLE. —CHEMICAL ANALYSIS
INADEQUATE TO THE ANALYSIS OF SOILS IN DISCOVERING THE
CAUSES OF FERTILITY. — THE SYNTHETIC METHOD TEACHES THAT
ANALYSIS NEED CONCERN ITSELF WITH FOUR ELEMENTS ONLY.—
THE SOIL CONSISTS OF MECHANICAL AND ASSIMILBLE AGENTS, THE
LATTER BEING ORGANIC AND MINERAL.— REVIEW OF THE ANA-
LYTICAL LABOURS OF CHEMISTS; CAUSES OF THEIR FAILURE. — THE
THREE MOST IMPORTANT QUESTIONS REMAINED UNSOLVED —“' HOW
MUCH WHEAT WILL A GIVEN SOIL PRODUCE?” ‘‘ WHAT WILL BE
THE BEST MANURE FOR IT, AND HOW MUCH MUST BE EMPLOYED ?”’
“HOW LONG WILLITS EFFECTS CONTINUE??? —THE ELEMENTS OF
FERTILITY IN A SOIL MUST EXIST IN AN ASSIMILABLE FORM, SO THAT
WATER CAN DISSOLVE THEM AND CONVEY THEM TO THE INTERIOR
OF THE PLANT THROUGH THE SPONGIOLES OF THE ROOTS.— THE
BEST RE-AGENT IN ANALYSING SOILS IS THE PLANT ITSELF, AS IS
SHOWN BY THE RESULT TO THE CROPS OF SUPPRESSING ONE OF THE
FOUR ESSENTIAL FERTILIZING AGENTS, — THIS NEW METHOD BAN-
ISHES ALL HYPOTHESIS, AND ADAPTS ITSELF TO EVERY WANT OF
CULTIVATION. — RESULT OF EXPERIMENTS,
45

PHOT URH FOUR TE

Since chemical analysis has arrived at the discovery
of the composition of most of the materials that render
service to mankind, science has become accustomed to
regard among the properties of bodies only that of
their elements modified by association, and the various
forms of which this association is susceptible.

This theoretical view is more and more verified in
proportion as chemistry penetrates deeper into the
study of nature: so much so that, now-a-days, the
idea of the chemical elements, such as proceeded from
the researches of the immortal Lavoisier, governs all
the sciences which are occupied with matter and its
transformations. The science of vegetation cannot
remain a stranger to this movement, and the attempts
directed to the end of bringing it under the common
law have not failed. No sooner had chemical analysis
begun to assume a scientific character, than it attempted
to discover in the soil the causes of its fertility. But,
too weak as yet to accomplish such a task, it exhausted
itself in impotent efforts, and we may say that, notwith-
standing the progress which has brought this young

46

47
science rapidly to the maturity we witness at the pres-
ent day, it has none the less remained unfruitful with
regard to agricultural problems.

The reason of this is very plain. Suppose we require
of a chemist the analysis of a mineral containing traces
of gold, without informing him of the presence of this
precious metal in it. His attention will be given to
each of the predominating elements; as for the gold,
it will escape his researches If, on the contrary, you
point out to him the element you desire to prove the
presence and quantity of, the chemist will proceed quite
differently. Ne will begin by removing from his analy-
sis all unimportant substances. Concerning himself
only with the gold you have named to him, he will suc-
eeed in concentrating it in a very small quantity of
matter, where its presence will be manifested and its
determination easy.

When engaged in the analysis of soils, chomists
have hitherto found themselves in the first of these
two alternatives. Ignorant of what the elements of
the soil were which played an important part in the
formation of vegetables, they attributed this faculty to
the agents which predominated in the soil examined.
‘he direction of their analyses thus varied according
to the various hypotheses which led them to a more or
less happy intuition, or to the assertions more or less
well founded of agriculturists.

To change this state of things, we must substitute

48

for these hypotheses a certain knowledge which indi-
cates, with absolute precision and rigor, the elements
which analysis must occupy itself with, and if you wiil
call to mind the facts established at the last lecture,
you will have no difficulty in admitting that this knowl-
edge is at the present time in a very promising condi-
tion.

For we know that there exists in the soil materials
which do not enter into vegetable production except as
a support to the roots, thus realizing a kind of recipi-
ent for the useful elements. We designate them by
the name of mechanical agents.

We call assimilable agents all those which, at a given
moment, penetrate the plant in the state of aqueous
solution, to form afterwards an integral part of its tis-
sues.

Lastly, we rank ina third class the assimilable agents
in reserve, all the organic and mineral debris which
contain useful elements, but which cannot give them
up to water until after a previous decomposition.

We are thus led to the following classification of the
elements of the soil, a truly natural classification, as it
rests upon the facts which we have derived from the
results of cultivation itself.

49

COMPOSITION OF A FERTILE SOIL.

Sand.
1. Mechanical agents....... Clay.
‘( Gravel.

Humus.
Organic ~ Nitrates.
Ammoniacal Salts.

( Potassa.
2. Active assimi- Soda.
lable agents. Lime.

Magnesia.
Soluble Silica.
Mineral } Sulphuric Acid.
Phosphoric Acid.
Chlorine.
Oxide of Iron.
| Oxide of Manganese.

3. Assimilable { Undecomposed organic matters.
agents in reserve. { Undecomposed fragments of rocks.

It is by ignoring or mistaking this classification
that the most skilful chemists have failed to arrive at
any useful result. Still, it will not be uninteresting to
pass their attempts in review.

Sir Humphrey Davy, one of the greatest chemists
England has produced, conceived the idea of submit-
ting to analysis various soils celebrated for their fertility,
hoping thus to arrive at the recognition of something
common between them, some preponderating element
to which their agricultural properties might legitimately
be attributed.

The following are the results at which he arrived:

a
~

Hop land....
Pamnips .. . 2
Wheat......
Very fertile. .

Very good quality..

Excellent pasturage.

Siliceous
Sand.

66.3
88.9
60.0
60.0
83.3

9.1

Silex.

5.2
ef
12.8
16.4
7.0
12.7

Carbonate | Carbonate |Oxyde| Salts and | Sulphate

pe Lathe: Mo gueaih, Hane

3.3 4.8 8.0 2

i eee f as 0.3
PE26 12 a “

14.0 5.6 se 1.2

6.8 OF 7 as 0.8

6.4 57.3 a 1.8

organic
matters.

8.0
0.6
4.4
2.8
1.4
12.7

of

Lime.

0.5

“

ce

ce

51

By an inspection of this Table, we perceive how lit-
tle experience confirms the views of this celebrated
chemist. He only proved dissimilarities between all
the soils examined, and yet all were fertile.

How can such a failure be explained? If Davy
had been aware of the facts which I have explained
to you at our previous lecture, and with that summary
classification which has engaged our attention, it would
have been easy for him to see that, in his analyses, he
had taken no account of the agents which alone assure
the fertility of the soil. He makes no mention of po-
tassa, phosphate of lime, or nitrogenous matters, princi-
ples without which production is impossible. Davy
analyzed the ore, without concerning himself with the
precious metal. But could it have been otherwise at
the date of his labors? Chemistry had then only
just got out of its leading-strings, and possessed but
very vague notions of the life of plants, the result of
empirical observations which no rational union had yet
arranged.

Again, far from perceiving the true cause of Davy’s
want of success, the science of his day drew a very
singular conclusion from his labors. It was thought
that the elements of the soil had no influence upon its
fertility, and that if it were desired to find a reason for
its agricultural qualities it must be sought in the study
of its physical properties.

This false interpretation has not been without its
advantage to science. It has caused the production of

4

extensive works on the part of physicists, and particu-
larly from Schubler, who specially applied himself to
researches of this kind.

The result was a profound knowledge of the mechani-
cal properties of the dominant agents of the soil, prop-
erties, the influence of which, although secondary,
nevertheless merit a serious examination.

The labors of the physicists were scarcely a whit
happier than those of the chemists, and the problem
remained intact in spite of these two series of attempts.
As usually happens, after excessive contradictions, they
next attempted to reconcile the two methods, and M.
Berthier undertook analyses in which he endeavored to
take account of both the physical properties and the
chemical composition of soils. Here is an example.

SOIL OF THE VINEYARDS OF POMARD (COTE D’OR).

No: 1. No. 2.
Quartz remaining upon the hair sieve.... 2.6 2.5
Quartz remaining upon the silk sieve.... 1.4 2.0
Quartz obtained by levigation............ 8.5 4.6
Exceedingly fine quartz........cssesceces 17.5 13.3
WamNmed Silex ten-oy ccies osre lee ocr s/s 10.2 7.8
wadiann pn EHS aeaclctats ‘slag Kips Maus dep tnrmiowie 5.1 ey cee 3.9 4
Hydrate Of ir0n....... cs. 2 sens cncccncesee 9.8 7.4
Calcareous stone remaining upon the hair
Se ob Soon. Jose 16 38d o6 eobco: 23.0 38.5
Ditto remaining upon the silk sieve ..... 2.9 10.0
Calcareous stone in fine grains.......... 7.8 2.2
ey » in exceedingly fine grains 11.3 7.8
Organic matters............. Riis es etote hays ek 2.0
— 101.1 —— 102.0

After the labors of M. Berthier, science was not

53

more advanced than before, and the most skilful
chemist was still without a reply to the three ques-
tions which interested agriculturists in the highest
degree : —

1. How much wheat will such a soil produce ?

2. What will be the best manure for it, and how
much must be employed ?

3. How long will its effect continue ?

Now-a-days science seems to have made a step. In-
stead of contenting itself with measuring the mechani-
cal elements of the soil, it determines, with the great-
est care all the elements of fertility: lime, magnesia,
the alkalies, phosphoric acid, nitrogen, &c., as, more-
over, we may convince ourselves by the following
example : —

ANALYSIS OF A SOIL IN THE ENVIRONS OF
CHALONS-SUR-MARNE.

1. Mechanical Analysis.

Fine Matters ......... 52.50 | Sand and Gravel...... 42,25
2, Chemical Analysis.

Organic matter......-. VSO (Dame on oe aes oss os 40.50
Hygrometic moisture. 2.70 | Magnesia .....-.+-++++> traces.
Water of combination. . 5.92 | Alkalies ..........++5- 0.38
Carbonic acid ........- 33.20 | Sulphuric acid......-.- 0.28
Quartz sand ...-...-:+- 3.10 | Phosphoric acid ....... 0.12
OC ae eee cement rris 6.00 | Nitrogen and chlorine . . traces.
Attackable silica....... 3.10

Oxide of iron .......-+ 2.00 99.25

ATTIRE ose x ese shes 0.15

+

or

But these laborious and complete analyses, in which
nothing is forgotten, are still useless to agriculture, and
cannot, any more than the preceding, reply to the
questions that essentially concern it.

In fact, for a soil to be fertile, it is not sufficient that
it contains potassa, phosphoric acid, lime, and nitro-
gen: these agents must also exist in an assimilable
form; that is to say, in a state in which the water in
the soil can dissolve them, to convey them into the
interior of plants through the spongioles of their
roots.

Suppose that a soil contains a feldspathic sand in-
stead ofa quartz sand. Chemical analysis would show
the presence of all the agents useful to vegetation, and
still this soil would be of a desolating sterility ; for, in
feldspar, these bodies are combined in silicates which
water cannot dissolve.

Not only, then, is it necessary to determine the
presence and quantity of the useful elements, but
analysis, to be fruitful, must also occupy itself with the
kind of combinations in which they are engaged. I
have myself sought the solution of the problem in this
direction; and, to remove from the first attempt that
portion of the soil which can contribute nothing to its
fertility, I have commenced by washing the soil with
distilled water, hoping to arrive, by evaporating the
liquid obtained, at concentrating in a small bulk the

only principles which it was necessary to take notice
of.

ay)

Submitted to this treatment, the soil of Vincennes
yielded to water only a very little potassa, and no
phosphates at all. Nevertheless, three successive
crops of wheat have extracted 188lbs. of phosphoric
acid and 2036lbs. of potassa. The exhaustion by dis-
tilled water is therefore much less efficacious than the
natural exhaustion. In fact, in the soil the solvent
power of the water is greatly increased by the carbonic
acid with which it is constantly charged by the salts it
dissolves, and by the time during which it acts.

With the view of approaching nearer to the condi-
tions of solution in nature, I have attempted to exhaust
the soil by water slightly acidulated with hydrochlorie
acid. But then I fell into the opposite extreme.
While the three crops of wheat exhausted the soil and
extracted from it only 188lbs. of phosphoric acid,
acidulated water indicated 1000Ibs. the acre. In fact,
chemistry has not been more powerful in my hands
than in those of my predecessors, and the failure must
be attributed to the insufficiency of the methods of
exhaustion at command.

Must we, then, despair of ever being able to analyze
the soil in a brief space of time by means of a labora-
tory susceptible of defining its agricultural properties
with certainty? JI do not think so. The problem,
although not hitherto solved, does not appear to be in-
soluble. The whole difficulty consists in extracting
from the soil every thing that plants are susceptible of
drawing from it, without going beyond what they do
themselves.

D6

Perhaps dialysis, from which Mr. Graham has de-
rived such admirable results, may, by its application
to the study of soils, lead to more useful data than
those I have criticised. But these methods are not
yet instituted, and I speak of them only as things
hoped for.

Leaving aside, then, the chemistry of the laboratory,
the present weakness of which we fully recognize, and
taking up the results [ have previously explained to
you, we deduce a more certain method, one in which
we employ no other reagent than the plant itself.

If you recall to mind what I said in our last lecture,
you will remember that four essential agents suffice to
assure the fertility of soils, and that the suppression of
one of them lowers the yield to a very important ex-
tent. Now, conceive a soil naturally provided with
phosphates, is it not evident that the suppression of
phosphates in the manure supplied to it will produce
no bad effect? Reciprocally, whenever the manure
without phosphates produces a crop equal to that from
a manure which does contain it, we shall be justified in
admitting that the soil is naturally provided with it.

Do you wish to be similarly instructed with regard
to lime, potassa, and nitrogenous matter? Cultivate
the same soil with manure deficient in lime, potassa,
and nitrogenous matter, and, according as they produce
» good or bad crops, draw your conclusions as to fhe
presence or absence of these agents of fertility.

This new method banishes all hypothesis, since it

DT
rests upon the following facts, proved by experience,
namely : —

1. That the association of minerals and an assimi-
lable nitrogenous matter produces good crops every-
where; while isolated, these agents are always inert.

2. That lime produces a useful effect only in pre-
sence of humus.

3. That lime and humus produce great effects only
in a soil provided with minerals and nitrogenous mat-
ter.

This method adapts itself to all the wants of cultiva-
tion, since it is sufficient to scatter a few handfuls of a
fertilizing manure upon a field, to indicate, at the time
of harvest, what the soil contains, what it wants, and,
consequently, what must be added to it to render it
fertile.

Lastly, it is essentially practicable, as it requires no
difficult manipulation, no apparatus, and employs only
the usual processes of cultivation.

It now remains for us to examine to what degree it
is precise and exact, and with that to put it to the test
of experiment.

The following are the results obtained in three differ-
ent soils, compared with those given by calcined sand
under similar conditions.

D8

Complete Manure.

“cc

1 2 3 4 5 6 ¥
~~ oO. ~~ 5 ie 2s : 42 - +
sf | BS | 828) 828) 88 | Bs] 28
sa | £8 |S8e(/220| 28 | SE 188
_ —_ =o! 4 _ 2 =
BS | 83 |ESA (Fas) Fo | BT | 8 |
A
Calcined | |
Sand. 6 24 8 0 7 22 32
Soil from
| Gascogne. | 55 | 32 ee a Lala 22 ares
} | j
| Soil from | |
| Bretagne. 4 | BOs aG | 9 | 18 dy
|
Soil of |

Vincennes. | ll

The soil from the landes of Gascogne, without ma-
nure, was not more fertile than calcined sand: with
complete manure, its yield was equal to that of calcined
sand with humus and complete manure, this soil there-
fore contained humus.

Reasoning in the same manner with regard to the
elements, we see that it contains neither nitrogenous
matter, nor potassa, nor lime, since, in their absence,
it is not more fertile than calcined sand. On the other
hand, it contains traces of phosphoric acid, for in the

, experiment where it was not added, it yielded a light
crop, while in the sand the plants invariably perished.

As for the soil of the /andes of Bretagne, these ex-

D9

periments show it contains humus, a little nitrogenous
matter, a little potassa, and very small quantities of
phosphates.

The soil of Vincennes, examined in the same man-
ner, showed itself to be rich in humus, phosphates, po-
tassa and lime, but poor in nitrogenous matter.

These are positive data, which we can employ in fer-
tilizing soils. Let us now see to what extent they
were verified in practice on a large scale.

60

Year.
Straw
1861
Grain
Straw
1862
Grain
Straw
1863
Grain

Average. .

CULTIVATION OF WHEAT. CROP PER ACRE.
Complete Manure.
Complete peep out Without Without Without
Nitrogenous ;
Manure. Matione Minerals, Potassa, Phosphates,
Ibs. Ibs. Ibs. lbs. Ibs.
9.100 68.64 7.150 9.966 11.002
14.380 11.550 12.650 14.960 16.282
5.280 4.686 5.500 4.994 5.280
8.646 7.326 7.942 8.866 9.966 ]
12.826 10.670 11.210 12.002 14.806
4.180 3.334 3.278 4.136 4.840 §
15.270 6.666 10.648 11.520 12.210
23.250 9.497 14.808 16.554 16.566
8.250 2.831 4,160 5.034 4.356
16.992 10.571 12.892 14.839 15.895

61

This table shows that, without phosphates, the crop
was nearly equal to what it was with a complete
manure: that without potassa it sensibly diminished,
and that without nitrogenous substances, it was very
inferior. These results are exactly like those derived
from experiments on a small scale. But do you wish
to see with what precision these results agree? Sup-
pose the crop with complete manure equal to 35, as it
was on the small scale, and calculate the others with
reference to that.

You will thus be led to the following comparison :

Complete Manure.
—_—A—— $$,

co

Complete Without Without ~- Without
Manure. Nitrogen Potassa, Phosphates,

Matter.
Cultivation on
small seale. 30 20 28 28
Cultivation on
large scale. . 35 21.7 30 32

I will ask you, is it possible to attain to a more
perfect concordance, and is it not the most satisfactory
proof of the excellence of the method I have com-
municated to you?

The plant therefore becomes in our hands one of
the most perfect instruments of analysis, the only one,
in the present state of science, susceptible of making
known, practically, the composition of soils. But I
shall give to this proposition a still more striking

62

demonstration, by showing you to what extent this
test goes.

We have seen that, in calcined sand and complete
manure without phosphates, we succeed in causing the
death of plants. In the soil from the landes of Gas-
cogne the same compound gave a crop equal to 6,
which proves, as we have stated, the presence of small
quantities of phosphates in the soil.

To lewt. of calcined sand and complete manure
without phosphates, add only +3, of 1 per 100 of
phosphate of lime, that is to say, zogoaq of the
weight of the soil. Immediately the yield rises to 6,
as in the soil of the landes of Gascogne.

We are then correct in saying that vegetation re-
veals to us with certainty, in this soil, the presence
of s5d500 Of phosphate of lime.

What chemical process, let me ask, can attain to
such limits ?

The accuracy of this method, in relation to the
other elements, is no less remarkable. yo%oq of
potassa cause the yield to pass from 8 to 32: y5do5
of lime in presence of humus raises it from 12 to 24.

We are then assuredly in possession of a means of
analysis, the perfection of which yields in no respect
to the most delicate processes of the chemical labora-
tory, the indications of which are verified exactly by
cultivation on a large scale, capable, consequently, of
throwing a sure light upon agricultural operations.

To put it into practice, the agriculturist will only

63

have to reserve some square plots in a field, to.which
he will give complete and partial manures of the fol-
lowing composition for the surface of an acre:

n .
$ sel8a.|/e¢/ 32/3
2 joscjeial §2/68 |5a
EI SwelSsciis|se/S8
S BSABE°|ES | ES BO
Pa HA , oe
Ibs. | Ibs. | Ibs. ! Ibs. | Ibs. | Ibs.
Phosphate of Lime....... 352 | 352 |..... 352 |.....| 352
Carbonate of Potassa..... BOD |. BOD |» aaraialeaieia’s 352 | 352
Quiek, Lime}... .odee5.0% 132 | 132 |..... | 182 | 132}...
Nitrate of Soda, (nitroge-
nous matter). ....:...0.5% 488 |.... | 488 | 488 | 488 | 488

At the harvest he will carefully note the results ob-
tained, and for the following year he will fix upon that
which his soil requires, and, consequently, upon that
which he must give to it to restore its original fertility,
and to fertilize all the plots, if they do not give good
results.

For several years past, geologists have endeavored
to prepare maps in which they represented, by particu-
lar tints, soils of different geological construction.
These maps assumed to come to the aid of the agri-
culturist, but they completely failed, like the method
of analysis upon which they were founded. By the
processes I have explained to you, we can now ascer-
tain the real agricultural properties of soils, and conse-
quently resume the task of the geologists with the aid
of data from cultivation itself. We shall in this man-

64

ner arrive at constructing true agricultural maps.
What is required? Some experimental fields anal-
ogous to those at Vincennes, disseminated over the
surface of France, upon lands belonging to the princi-
pal geological types. The centralization of the results
obtained will permit of the drawing up of an exact
inventory of the agricultural resources of the Empire.

To give you some idea of the benefit which may be
derived in this object, from our own method, it will
be sufficient for me to compare the results of the farm
at Vincennes with those obtained in England by
Messrs. Laws and Gilbert, who also have instituted,
at their farm at Rothamstead, experiments in cultiva-
tion with manures of known composition.

MESSRS. LAW & GILBERT’S RESULTS.

Complete Minerals without) Nitrogenous |
| Manure. Matters. with Minerals. |

Years. | Nitrogenous Matters
|

lbs. : Ibs.
vieaeianall 9,656 4,426 6,067
1855 14,386) 8,342 13,925

Grain | 4,730

( Straw 9,480 | ane) 3,916
1856 14,420 8,012 11,629

(Grain | 4,940 2,952 ) 7,713
Straw oO) 4,100 4,196

1857 16,230 7,670 11,496
Grain |:6,770.5 | 3,570 7,800

Mean. . | 15,010) 10,208 | 12,324!
|

| eh a ne

65

RESULTS AT VINCENNES
Mean 17.992 10.57 12.824

With complete manure the mean yield is nearly the
same, without nitrogenous matter the yield at Rotham-
stead is very inferior. Messrs. Laws and Gulbert’s
land therefore contains less nitrogenous matter than
‘that of Vincennes.

Without minerals, the yields are very nearly alike,
the two soils have therefore nearly the same mineral
richness. There is a slight advantage for that of
Vincennes. .

Thus you perceive that, armed with our method, we
can make a retrospective analysis of all the soils of
which we possess information of the exact culture.
Still better when the documents collected for the pur-
pose are as complete as possible.

But it will not be sufficient to point out to you the
agents by means of which we can analyze the soil and
fertilize it. To give you the power to manage these
valuable fertilizers, I must also tell you under what
form they must be administered to plants, and from
what sources of human industry they can be provided.
This will form the subject of my next lecture.

ANALYSIS.

THE IDEAL MANURE, OR MANURE par excellence. — COMPARISON
BETWEEN THE COMPOSITION OF IDEAL AND PRACTICAL MANURE.
— DEFINITION OF nitrogenous matter.— SOURCES FROM WHENCE
NITRATES MAY BE OBTAINED.— FROM THE ATMOSPHERE: FROM THE
AMMONIACAL SALTS OBTAINED IN COAL-GAS MANUFACTURE: FROM
SEWAGE WATERS,.— THE HYDROCHLORATE THE BEST FORM OF AM-
MONIA TO BE EMPLOYED.— VALUE OF NITRATE OF POTASSA, AND
OF NITRATE OF SODA. — ANIMAL AND VEGETABLE REFUSE A SOURCE
OF NITROGEN.—TIIE PHOSPHATES; IN CHALK, NODULES, COPRO-
LITES, APATITE, OSSEOUS BRECCIA, SUGAR REFINER’S CHARCOAL,
BONES, GUANO.— PHOSPHATE OF LIME.— POTASSA, NITRATE, CAR-
BONATE.— NEW SOURCES FOR THE SUPPLY OF PCTASSA, FROM SEA
WATER AND FELSPARS,

LG TU eh Pay a.

I HAVE announced to you for to-day’s lecture, the
particular study of the agents we can employ to fer-
tilize or analyze the soil. But before entering upon

details, it is necessary to note the point at which we
66

67

have arrived, and to explain to you the idea of manure
such as it is when disengaged from the principles I
have previously laid down, ~—

We have shown that the fertility of soils depends
on the presence, in their substance, of the elements
which we have called active assimilable agents. From
this it evidently results that, to render a barren soil
fertile, it will suffice, in most cases, to add the whole of
these elements to it. This is, in fact, what the experi-
ment with calcined sand proves, where such a mixture
realizes conditions of fertility equivalent to those of a
good soil. We may say, then, that this mixture is the
ideal mixture, the manure par excellence.

But when we work upon arable land, it is impossible
that it should not already contain a portion of the
necessary elements. Some, such as iron and man-
ganese, of which plants take up only infinitesimal
quantities, exist almost everywhere. Generally, then,
there need be no fear of their deficiency. We may
therefore dispense with introducing them into a prac-
tical manure.

We also banish from its composition all the agents
of which the mode of action is only imperfectly
known to us, or in which we are still ignorant of the
form susceptible of manifesting their influence. It is
for this reason that we exclude soda, magnesia, sul-
phuric acid, and chlorine.

Science, from its nature, is essentially progressive,
and I do not pretend that I possess the whole truth, or
that nothing remains to be discovered. Tar from this,

68

I hope, on the contrary, | may be permitted to add
fresh knowledge to that which I have already imparted
to you, and it is with this aim that I actively pursue
my researches. Let us then banish every exclusive
idea, and construct a manure as perfect as the science
from which it is deduced, and content ourselves with
composing it of elements, the action of which is wholly
definite, the useful form perfectly known, and of which
plants require important quantities. This practical
manure will represent all that we can obtain most per-
fect in the present state of our knowledge, it will be
sufficient in the generality of cases for all the require-
ments of cultivation, and if the future be called to
make useful additions, we can at least assert that we
shall have nothing to retract.

These considerations leads us to the conclusions ex-
pressed in the following table.

Soluble Silica.
Sulphuric Acid.
Phosphoric Acid. Phosphate.

Chlorine.

{

Ideal Manure. Practical Manure.
Humus.
Nitrates. Nitrogenous
Organic. { Ammoniacal Salts, matter.
| Potassa. Potassa.
| Soda.
Active Assimi- | igs iia,
lable Agents. | Magnesia.

Mineral.

Oxide of Iren.

| Oxide of Manganse.

69

Among the constituents of the practical manure
figures lime, which is easily procured everywhere, and
with the history of which nearly everybody is ac-
quainted. J may therefore dispense with repeating it
to you, preferring to reserve my explanations for less
known materials, and which it is less easy to obtain.

I call nitrogenous matter every principle which in-
cludes nitrogen among the number of its elements, and
capable of supplying it to vegetation. This includes
the remains of all beings that have lived. Buried in
the soil, they undergo slow decomposition, in conse-
quence of which their nitrogen separates partly in the
state of carbonate of ammonia or of nitric acid. These
_ substances are retained in the soil by humus or by
clay, and water afterwards dissolves them gradually
and conveys them into the interior of vegetables. But,
as nitrogenous matters of animal or vegetable origin
are useful only after being transformed into ammoniacal
salts or nitrates, there is every advantage in having
recourse to these products ; ; this is why, from the
present point of view, we give them also, by th
the denomination of nitrogenous matters.

I have already shown you the efficacy of the nitrates
and of the ammoniacal salts, in our second lecture, and
{ need not return to the subject, but limit myself to
making known to you the sources from whence we
may obtain these compounds.

The great natural store of nitrogen is the atmos-
phere. We have seen that vegetation in general en-

70.

joys the faculty of drawing from it the greater portion
of the nitrogen it assimilates. The idea of imitating
nature, and of procuring nitrogenous compounds by
causing the nitrogen of the air to enter into combina-
tion, has for a long time presented itself to the minds
of chemists. Unfortunately, free nitrogen possesses
only very feeble affinities, which renders the problem
thus put by chemistry extremely difficult of solution.
Recently, however, Messrs. Sourdeval and Margueritte
have succeeded in producing ammonia with the nitro.
gen of the air by a very interesting reaction, but still
too expensive for it ever to become an important source.
These chemists made atmospheric nitrogen pass over
carbon impregnated with baryta, at a very high tem-
perature. In this manner cyanide of barium Ba 0? N
is produced, the nitrogen of which is converted into
ammonia by a current of steam from water. This
remarkable experiment realizes the scientific solution
of the problem, but it does not give the economic
solution. |

For many years past the manufacture of coal gas
has thrown very important quantities of ammoniacal
salts into commerce. We know that coal contains 75
per 100 of nitrogen, which is partially disengaged
during its distillation. This ammonia is condensed in
acid waters, the evaporation of which furnishes am-
moniacal salts. This course is certainly not to be
despised, but it is far from being sufficient.

England consumes annually 1,000,000 tons of coal

71

in the manufacture of gas. From this results about
10,000 tons of ammoniacal salts, which scarcely suffices
to supply 50,000 acres of arable land with nitrogenous
manure. If we remember that the territory of France
contains about 125,000,000 acres of cultivated land,
we shall have an idea of the importance of the outlet
which agriculture presents to ammoniacal salts, and of
the insufficiency of gas manufacture to supply this
consumption. It must not be forgotten, however, that
this is a source scarcely turned to full account, which
rests upon a manufacture very rich in its future
promise, and which would receive important develop-
ments if the production of coke in closed chambers
were generally substituted for its manufacture under
the open sky.

The ammoniacal salts arising from the distillation of
coal merit, besides, all our sympathies, for they restore
to the vegetation of our times a portion of the nitrogen
which has contributed in former times to the immense
vegetable formations of which coal presents us the
débris. They thus place at the disposal of human
industry considerable quantities of combined nitrogen,
which, in this manufacture, remain entirely lost, buried
in the bowels of the earth.

There exists another very abundant source of am-
monia: in sewage waters. These waters have for a
long time been the object of a certain manufacture.
They are distilled with lime in large leaden retorts.

The ammonia disengaged is collected in diluted hy-

72

drochloric acid, the evaporation of which yields sal
ammoniac. But the heat lost at the end of each opera-
tion raises the cost of this product too high for the
manufacture to become extensive. Messrs. Sourdeval
and Margueritte have recently applied to this distilla-
tion a continuous apparatus similar to that which ren-
ders such great service in the manufacture of alcohol.
By this happy innovation the cost of production has
been greatly reduced, and these gentlemen, in a single
manufactory, have already succeeded in manufacturing
about 6 tons of sal ammoniac per day, which they sell
at a very moderate price. This manufacture, which is
susceptible of very great extension, may become a
source of wealth to agriculture, for it will permit of
returning to it a great portion of the combined nitro-
gen, which it continually withdraws in the form of
crops, and which thus accumulates in cities, where it
is generally lost, to the great detriment of the public
health.

Whatever be the source of the ammonia, its hydro-
chlorate (N H* Cl) appears to be the most advan-
tageous form under which it can be employed. It has
always given us good results. To light lands it may
be given in quantities of 440lbs., representing 114lbs.
of nitrogen, per acre. But upon strong lands this
quantity would be excessive, unless the season was
wet: it would cause the wheat to be laid. In such
cases, we must reduce it to 260 or 300lbs. at the most,
which, at the rate of 17 shillings the cwt., makes a

73

manure of 37s. to 47s. In sal ammoniac, nitrogen
costs 8d. per pound.

Instead of this salt, we can employ Peruvian nitrate
of soda, the price of which is also 17 shillings the
ewt. Only, as it contains less nitrogen than sal am-
moniac, it is dearer. The cost of its nitrogen is about
ls. per lb. Whenever, then, it is proposed to give
nitrogenous matter only to the soil, it is best to have
recourse to sal ammoniac. But when we wish to make
it enter into a mixture constituting a complete manure,
and consequently containing lime, a mixture which
may be kept and sent to a distance, then it is prefer-
able to take nitrate of soda, because, under the influ-
ence of moisture, lime in time decomposes the sal
ammoniac, and thus causes the loss of a portion of the
useful nitrogen.

To employ nitrate of soda, it suffices to scatter it on
the soil, the same way as seed, and afterwards harrow
it in, so as to mix it well with the upper layer of the
soil. With sal ammoniac it is preferable to first mix it
with two or three times its weight of moist earth,
then leave it to dry, and spread it afterwards. By this
method its diffusion is very uniform,

To give nitrogen to the crops, we can also, besides

_nitrates and ammoniacal salts, have recourse to all nitro-
genous matters of animal or vegetable origin which can
be procured economically, provided they are readily
decomposed in the substance of arable land, without
which their useful effect may be wasted for a long time.

74

In the employment of these matters we must also take
into account, that only about one-third of their nitro-
gen, separated during their decomposition to the ele-
mentary state, can be profitable to vegetation as com-
bined nitrogen.

Let us now proceed to the study of the phosphates.

Phosphoric acid is widely diffused in nature: it ex-
ists in very small proportions in most of the crystalline
rocks, where it is in combination with alumina and ox-
ide of iron. In this state it is useless to vegetation, as
water cannot dissolve it. In the sedimentary soils, it
presents itself, on the contrary, under a form essentially
assimilable to that of phosphate of lime. But in gen-
eral, the soil contains only traces of it, some ten thou-
sandths at the most, and in many countries where cul-
tivation has been long continued, the soil has become
wholly exhausted of it. Fortunately, there exists upon
certain points of the globe, considerable quarries of it,
sufficiently abundant to repair the losses of the past
and secure the wealth of the future.

Chalk, which forms such immense deposits, always
contains phosphate of lime, —the proportion is much
greater the deeper we descend. At the base of the
cretaceous strata a peculiar mineral is met with, in
fragments of various sizes, which contain as much as
50 per cent. of phosphate of lime.

This product, which is very abundant, has been re-
cently discovered ; it is known under the name of nod-
ules, and promises to yield an inexhaustible supply to

To

agriculture. But there is another quite as extensive,
and much richer, and very easily worked : this is apa-
tite, which, in Spain, forms entire mountains, and can
be taken from the surface by the simplest means. Apa-
tite is a combination of tribasic phosphate of lime with
an equivalent of fluoride of calcium, 3 Ca O POF ++
Ca Fl. In this state the phosphate of lime is very as-
similable, but it is easy to disaggregate this rock and
render it accessible to vegetation. It is only necessary,
after reducing it to powder, to sprinkle it with its
weight of sulphuric acid diluted with an equal volume ©
of water. Sulphate of lime is thus produced, and acid
phosphate of lime, which is very soluble in water.

We can treat in the same manner the nodules and in
general the tribasic phosphate of lime, whatever its
origin. The acid phosphate encountering an excess of
carbonate of lime in the soil, passes to the state of neu-
tral phosphate, which is a condition most favorable to
its absorption by plants.

Before the discovery of the nodules which begin to
enter largely into practical agriculture, and of apatite,
which has only recently made its appearance, we have
had recourse, successively, to coprolites, a sort of phos-
phated concretion of animal origin, abundant quarries
of which exist; to the fossil bones found in caverns,
and in rocks known as osseous breccia: to the charcoal
black of sugar refineries, and also to the bones in a
natural state, after calcination, or after a previous boil-
ing to remove the fat, which are infinitely superior.

76

All these products have rendered, and can still render
great service, but there is another to which I desire
more particularly to call your attention, both on account
of the important part it has played in the agricultural
revolution we have witnessed, as in consideration of its
richness in phosphates, and of the abundance of its
sources. This is guano.

When this product began to be noticed about 1804,
no one then supposed that it was possible to find a sub-
stitute for the farm dung-hill. It was this that at-
tracted the attention of chemists and agriculturists to
artificial manures, and such was the state of ignorance
that continued to prevail till within a few years that the
fertilizing properties of guano were exclusively attrib-
uted to the nitrogen it contained. Whatever ideas
were entertained of its action, the good results it pro-
duced, showed, also for the first time, that it was possi-
ble to obtain very good crops by processes that finally
broke up the traditions of the past, and opened to ag-
riculture the entirely new path of artificial manure.

Guano forms extensive deposits upon the islands
scattered in the Pacific ocean, and upon the coast of
Peru. It is supposed to be produced by the excre-
ments of birds that feed upon fish. Its composition is
not quite favorable to this hypothesis. It contains
much more phosphoric acid, proportionally, than the
excrements of birds. It therefore seems to me more prob-
able that it contains both the excrements and the skele-
tons of birds. Whatever it be, guano containing both ni-

ied
|

trogen and assimilable phosphate of lime, constitutes
an essentially fertilizing substance. To convert it into
a complete manure, it is sufficient to add to it potassa
and lime. Guanos are not always of the same compo-
sition. Their richness in nitrogen varies from 5 to 14
per cent., and their contents in phosphates extend to
25 or 835 per 100. Therefore, before employing these
products, it is necessary to submit them to analysis,
both to guard against adulteration, to which they are
frequently exposed, and to ascertain the quantities that
should be employed.

Whatever the form under which we obtain phosphate
of lime, the proper quantity per acre is 160lbs. We
can previously convert it into phosphoric acid, as I be-
fore stated, and then begin by mixing it with two or
three times its weight of earth, leaving it to dry, and
afterwards spread it over the soil. We can thus em-
ploy it direct, but in this case it is important to dis-
tinguish that which is assimilable from that which is
not. Thus, apatite can never be turned to account in this
manner, for, notwithstanding the 80 per 100 of phos-
phate of lime it contains, its effects will be very doubt-
ful.

Hitherto the acid phosphate has been employed ex-
clusively in England. In France, on the contrary, it is
the direct employment which has prevailed. But I
have no doubt that our agriculturists will ultimately
imitate our neighbours in this point, which seems to me
to be the wiser plan.

78

In our practical manure we have included a fourth
element, potassa: it remains for me to give you its
history. |

I have previously shown you the necessity for its
presence in the soil, and the impossibility of substitut-
ing soda for it, which has now replaced it in most man-
ufacturing processes. With manure, substitutions are
impossible, for each principle has distinct and exclusive
properties. The vegetable is a reagent, which distin-
guishes the slightest shades of difference. You will
have a fresh proof of this on studying the form under
which the potassa has most efficacy. Chloride of potas-
sium, sulphate of potassa, and the carbonate of the
same base, are all three soluble in water; all three are
absorbed by the roots; yet the chloride is completely
inactive, the sulphate produces only an insignificant ef:
fect, and the carbonate gives the best results. We also
obtain excellent effects with silicate of potassa contain-
ing sufficient silica to prevent its being attacked by wa-
ter, except very slowly. Itis under this form that I
have always employed potassa in my experiments on a
small scale. This salt possesses the advantage of fur-
nishing that alkali, in proportion, so to speak, to the
wants of the plant. But its employment on the large
scale is impossible, because its price is much too high.
Besides, it acts only after being converted into carbo-
nate under the influence of the carbonic acid in the
soil. It is therefore preferable to have direct recourse
to carbonate of potassa, which is both the most active ~

79

and the most economical form under which this agent
can be procured. |

There is, however, another salt, which would be much
more advantageous if it could be obtained at a low
price —viz. nitrate of potassa. It contains, at the
same time, 50 per 100 potassa and 14 per 100 nitrogen,
both eminently assimilable ; so that, mixed with phos-
phate of lime and lime, it constitutes a complete ma-
nure.

Unfortunately, its price is now 51s. per. ewt. If we
reckon the 153lbs. of nitrogen it contains at 15d.,
there still remains nearly 34s. for the 56lbs. of potassa,
which makes 68s. for 112Ibs., while in its other com-
pounds it costs only 42s 6d. per. cwt. Still, I have
thought it my duty to point out to you the advantages
of nitrate of potassa, which contains upwards of 60
per 100 of assimilable matter, in order to stimulate
chemists to seek the means of producing it economi-
cally.

The sources of potassa are not very numerous. For
several years past, all that has been found in commerce
was obtained by washing the ashes of plants. America
and Russia have for a long time been the principal
sources of supply; and it was an excellent thing —
that the wild desert should be impoverished to enrich
the industry of civilized countries

Along with the potashes of Russia and America,
that obtained in the manufacture of sugar from beet-
root has of late years been placed. This plant, in fact,

80

draws from the soil considerable quantities of potassa,
which is found in the residues of its distillation, or in
the molasses which remains after the crystallization of
its sugar. It is only necessary to evaporate the wash,
and calcine the residue, in order to obtain the carbo-
nate of potassa.

This manufacture has rapidly taken a great develop-
ment, and yields large profits to those engaged in it:
but it ruins the soil in which the beetroot is grown.

Twenty years ago, the beetroot grown in the neigh-
borhood of Lille gave a juice very rich in saccharine
matter ; at the present day, notwithstanding the addi-
tion of abundance of manure, and the application of
the most perfect system of cultivation, a juice contain-
ing more than 5 or 6 per 100 cannot be obtained, con-
sequently it is only available as food for cattle. The
reason of this is very plain: the manures employed
restore to the soil only very small quantities of potassa,
insufficient to repair the losses caused by the abundant
exportation just alluded to.

If the agriculturist desires to restore sugar to his
beetroot, he must supply the soil with potassa. But
then he will have to sacrifice the greater part of the
capital he has derived from the sale of the potassa in
former years.

Fortunately, new sources of a supply of potassa are
growing up, and I have every reason to believe that
agriculture will soon be supplied with it at a low price.

I shall first mention the extraction of potassa from grea-

81

sy wool, a branch of industry newly created by Messrs.
Maumeneé and Rogelé. These gentlemen collect the
waters of the first washing of the fleece before dyeing it,
evaporate them in large vats, and calcine the residue in
gas retorts. They thus obtain a very brilliant gas, and
as a residue crude carbonate of potassa, which is left
in the retorts.

This is a very interesting source, as it returns to the
service of industry a quantity of potassa which, hitherto,
was absolutely lost. But it is not susceptible of a very
great extension, and, in fact, it is still from the potassa
derived from agriculture that the return to the soil will
serve, in a certain measure, to maintain its fertility ;
but we cannot, in any way, raise its power of produc-
tion.

There is still another manufacture which promises,
at some future day, to reduce the price of the salts of
potassa.

Formerly, in the manufacture of sea salt, the mother-
waters were cast into the sea.

M. Balard, by patient and laborious studies, has suc-
ceeded in showing that these mother-waters may be
made to yield several useful salts at little expense.

M. Balard’s processes, modified by M. Merle, who is
established at Camargue, operate on a very large scale,
and produce considerable quantities of chloride of po-
tassium.

Sea water is submitted to a first evaporation in the
sun, in consequence of which it deposits four-fifths of

6

82 .

its chloride of sodium. The mother-waters are then
removed to special reservoirs, where they are suddenly
cooled to 32 degrees below freezing point by M. Carré’s
ice-making machine. At this low temperature double
decomposition takes place between the remaining chlo-
ride of sodium and the sulphate of magnesia, from
which results sulphate of soda, which crystallizes, and
chloride of magnesium, which remains in solution.
After the removal of the sulphate of soda the mother-
water contains only chloride of magnesium and chlo-
ride of potassium, which are made to deposit by a fresh
refrigeration in appropriate vessels. A washing after-
wards removes the chloride of magnesium, and leaves
the much less soluble chloride of potassium almost in
a state of purity.

I have visited M. Merle’s establishment, and I can
assure you that it is an exciting spectacle to see these
immense refrigerators working with the regularity of
steam engines, and continuously converting the mother-
waters in basins of several acres of surface into a snow
of sulphate of soda on the one hand and chloride of
potassium on the other. Here is an unlimited source
of this salt which will render the greatest services to
agriculture, when its conversion into carbonate shall be
arrived at, for, as I have before stated, it cannot be
employed in its natural state.

I was enthuiastic with this magnificent manufacture,
but I have recently learned of the existence of another,
which appears to me to be still more important.

83

Felspathic rocks, which in many countries exist in
inexhaustible masses, all contain potassa. Orthose con-
tains as much as 14 per 100. This potassa, engaged
in insoluble combinations, is completely inert ; it be-
comes accessible to vegetation only after the disaggre-
gation and decomposition of the rocks of which it forms
a part. Now these rocks decompose only with extreme
slowness under the influence of atmospheric agents ;
and to estimate the effect of this decomposition, we
must reckon time by geological periods.

To separate, by rapid and economical means, the
potassa contained in feldspars, has for a long time been
one of the most exciting problems of manufacturing
chemistry. Many solutions have been proposed, but
none of them have been successful in furnishing potassa
really cheap. Messrs. Ward and Wynants, of Brussels,
have solved this difficulty. They attack the feldspars
by treating them with carbonate of lime and fluoride
of calcium. The mass is next treated with water, which
extracts the whole of the potassa in the state of carbon-
ate. This reaction demands only a moderate tempera-
ture, and leaves a useful residue; it is therefore in
excellent practical condition. The inventors are striv-
ing to perfect the manufacture, and as the success of
their enterprise will be a great boon to agriculture, we
will conclude, gentlemen, by wishing them success.

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ANALYSIS.

SUMMARY OF THE FOREGOING PROPOSITIONS.—COMPARISON OF
THE NEW SYSTEM WITH PAST TRADITIONS AND PRACTICE.—THE
DUNGHILL THE MANURE par excellence. —ANALYSIS OF ITS CHEM-
ICAL CONSTITUENTS PROVES THAT IT CONTAINS THE FOUR ESSEN-
TIAL FERTILIZING AGENTS: PHOSPHORIC ACID, LIME, POTASSA,
AND NITROGENOUS MATTER.—AN EXACT BALANCE WITH REGARD
TO THESE FOUR AGENTS EXISTS AMONG ALL THE SYSTEMS OF
CULTIVATION, 7. €. BETWEEN THE QUANTITIES SUPPLIED BY THE
MANURE AND THAT CARRIED AWAY IN THE CROPS.— RESULTS OF
THE TRIENNIAL ROTATION OF CROPS.— RESULTS OF THE FIVE
YEARS’ SYSTEM.— MEAN ANNUAL RETURN OF THE TWO SYSTEMS. —
RESULTS OF VARIOUS CULTIVATIONS. — BEETROOT.— COLZA.— AD-
VANTAGES OF THE NEW SYSTEM; MAINTAINS THE FERTILITY OF
THE SOIL UNIMPAIRED, WHATEVER CROPS ARE CONTINUOUSLY
GROWN, WITHOUT ROTATION.— COMPARISON OF THE QUANTITIES
OF THE FOUR FERTILIZING AGENTS CONTAINED IN VARIOUS CROPS
AND IN THE COMPLETE MANURE. — POWER OF PRODUCTION OF THE
OLD PROCESSES OF CULTIVATION, COMPARED WITH THOSE OF
THE NEW SYSTEM.— LAW WHICH REGULATES THE NEW SYSTEM,
WHICH THROWS DOWN THE BARRIERS THAT HAVE HITHERTO
LIMITED PRODUCTION. — ESTIMATE OF THE RESULTS OF ITS ADOP-
TION IN FRANCE.—CONCLUSION.—- RESULTS OF THE HARVEST OF
1864, ON THE NEW SYSTEM.

85

LeOTUBRE. SIX TE.

Aut that I have stated to you previously may be sum-
med up in the two following propositions : —
1st. — There exists four regulating agents par excel-

lence in the production of vegetables : — nitro-
genous matter, phosphate of lime, potassa and
lime.

2nd. — To preserve to the earth its fertility, we must
supply it periodically with these four substances
in quantities equal to those removed by the
crops.

Such, in their greatest simplicity, are the conclusions
to which we have been unavoidably led by the discus-
sion of the scientific experiments upon vegetation. Let
us now examine to what point these results agree with
the results of practice, and the traditions of the past.

It is an admitted law in agriculture, that the soil will
not yield crops without manure, and the manure par
excellence which practice has realized, is the farm dung-
hill: — a collection of all the residues of the harvest, a
true caput morfuum of agricultural operations.

I do not know what the composition of the dung-hill
86

87

is, although I do not hesitate to assert that it includes
the four agents of vegetable production: for, without
their presence, its good effect would be incomprehen-
sible. Here is its analysis.

COMPOSITION OF THE DRY MANURE.

Imperial Farm Farm at
at Vincennes. Bochelbronn.

CORB Oa 5 neta ss saisinvde % 35.5
Organic |! Hydrogen........ Starks gi 59.65 4.2 65.50
Elements. | PRS PO POA EN 25.8
Nitrogen sidawsapciees os 2.08 2.00
Phosphoric. Acid... os dices as 0.88 1.00
| pulphtric Acid. oo... ease traces 0.65
Garbonie Add A3s) 80505 0.94 0.66
CT RMRIAR «col sieinchatl S ecsciee scp 0.70 0.20
; Ammonia and Oxide of Iron 0.68 2.03
Mineral BATS scale chet ins eiaravarghrerune 5.23 2.81
Elements. | vacnesia. ....6..s.csess0e- 0.82 1.20
RN es. etahig halt caret sae 2.46
EMD aS a Sac cael ee ae wees traces a
potable Silfes 7. fe. se. se sek 1.41
Sand. 20555. SURG. 25.66 a
100.09 100.78

(G. Ville.) (Boussingault. )

Thus we find in the manure, the use of which is con-
secrated by time, phosphoric acid, lime, potassa, and
nitrogenous matter, the same substances which our re-
searches have pointed out to us as being the starting
point of all production,

88

Assuredly this coincidence is not the effect of chance.
Our first proposition is then found to be fully verified.
Let us see if it is the same with the second. To that
end it will suffice to pass in review the system of cul-
tivation most generally pursued, and to show that an
exact balance, with regard to the four agents, exists
among them all, between the quantity brought by ma-
nure, and that carried off by the crops. Upon this
second point the demonstration will be as conclusive as
upon the first.

The most ancient system of cultivation, which neces-
sity devised, and practice recognized for maintaining
the fertility of the soil, is that which is still employed
in many countries under the name of triennial rotation.
Iivery three years the soil receives eight tons of ma-
nure per acre; it lies one year in fallow, and after-
wards produces two crops of wheat.

89

Weight | Weight of | Nitrogen Phosphoric} Potassa Lime

ee gap rl a a Oe a eg 2 a

Nature of the Crops. of the the Crops in and and
Crops. Diied. |the Crops.| Acid. Soda. _ Magnesia.
= Ibs. lbs. Ibs. lbs. Ibs. Ibs.
= Jet Year. 6. dea sce sn. sallow
in
se Grain 7.300 6.239 143.5 56.8 35.6 22.2
oe 2nd and 38rd Years, Wheat
~ Straw] 16.500 12.210 48.8 26.4 81.8 50.1
Qe
° ee Ss se
8 ;
3 dito ).0" Raa Co ere 23.800 18.449 192.3 83.2 117.4 72.8
©
tn —— el ———= ee
© :
are Manures Employed.............. 44.000 9.108 182.2 86.7 225.7 352.0
S
3
>)
—
o
an

90

You see that the balance is strikingly exact with re-
gard to the nitrogen and the phosphoric acid; as tothe
potassa and lime, it accumulates for the benefit of the
soil.

There is, then, nothing surprising in the fact of this
system maintaining the fertility of the soil, as nothing
is lost : but upon what conditions ?

To obtain these eight tons of manure required every
three years, we must raise cattle: to feed them requires
pasture : and to maintain this pasture requires irriga-
tion. It is then, in fact, to the water of irrigations that
the triennial rotation derives the four agents which it
exports under the form of grain, and to obtain them
it-is obliged to devote one-third of the farm to pasture.
Fallow and pasture, then, are the plagues of the trien-
nial system.

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cape from fallowing. It has succeeded by introducing
clover and similar plants into the rotation. In this
manner the rotation is extended to five years. The
crops of clover and roots have nourished the cattle, and
the system has sufficed for itself. Here, also, are the
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92

The triennial system accumulates important quanti-
ties of alkalies and lime in the soil as pure loss. But
through the clover and the roots, which have a marked
preference for these elements, they are in great mea-
sure turned to account. But the greatest advantage of
the five year rotation consists in its influence with re-
gard to nitrogen. You see that the cost of this ele-
ment was repaid in benefiting the crops, and if you seek
the plant to which this benefit is due, you will find that
it is the clover, to the vegetable that forms part of the
system.

You will remember that, while the cereals draw the
greater part of their nitrogen from the soil, vegetables,
on the contrary, obtain it from the atmosphere. Thus
you perceive, that the crop of wheat which follows the
clover is more abundant, and contains more nitrogen,
than that which preceded it— which proves that the
clover has not impoverished the soil of that element.

The five years’ rotation, therefore, realizes the con-
tinuous culture. It has two important advantages over
the preceding. 1. It derives a portion of the nitrogen
of the crops from the atmosphere. 2. It turns to ac-
count the excess of potassa and lime brought by the
manure, And the crops are also more abundant, as is
shown by the following table. _

93

MEAN ANNUAL RETURN OF THE TWO SYSTEMS.

Triennial. Quinquennial.

Ibs. lbs.
Weight of dried crop, per acre 2455 3131
Nitrogen contained in this crop 25 - 44

With the five years’ rotation, agriculture has been
brought to substitute the exportation of meat for that
of the cereals, and it has derived decided advantages
from the substitution ; for the sale of the cereals causes
a loss of potassa, phosphoric acid and nitrogen to the
farms, which cannot be compensated for except by a
supply of manure, or by irrigation. If, on the contra-
ry, the crops are consumed on the farm by the animals,
we find in their excrements almost the whole of the
phosphoric acid and potash contained in their food.
The quantities that fix themselves in their tissues and
bony structure, constitutes but a small loss. As to the
nitrogen, their respiration rejects about a third of it
into the atmosphere, in the gaseous state; the other
two-thirds return to the soil in the manure. This
would be a loss, inevitably impoverishing the farm,
without the clover, which derives an equivalent quan-
tity from the atmosphere. ;

It follows, from this, that the raising of cattle results
in preserving to the soil almost the whole of the four
agents which assures its fertility, and of procuring ben-
efits in money without sensibly impoverishing the
farm.

94

You see that the five years’ system no more opposes
our conclusions than the triennial; they receive, on
the contrary, an unexpected light, and consequently af-
ford them a striking confirmation.

But, you will ask, is this the best practice devised ?
No, Gentlemen. There exists a cultivation which re-
alizes considerable profits, and which, when well carried
out, causes almost no loss at all to the soil—that is
the manufacturing cultivation of beetroot. In this
case the exports are sugar or alcohol, substances ex-
clusively composed of carbon, oxygen, and hydrogen,
derived from water and the atmosphere. The ex-
pressed pulp serves to nourish the cattle, and almost
the whole of the useful elements are returned to the
soil, especially if care be taken to mix the residue of
distillation with the manure, instead of extracting the
potash.

Such are the systems of agriculture, developed dur-
ing ages of groupings, true are of promise to agricul-
ture, in which it had been rash to make the least at-
tack. Now we see them brought to rational and _ posi-
tive notions, and science, which has learned to unveil
the mysteries of their success, will learn also to give
them the last improvement of which they are suscepti-
ble. Without quitting the ways of the past, it will
point outa simpler and more perfect method, which
will be the ideal realization of the principle to which
practical agriculture has always instinctively endeav-
ored to conform itself, and constantly approached, and
which we can now formularize in few words,

95

Cultivate the soil, and realize its profits, without
impoverishing it of the four agents which assure its
fertility.

In all the systems I have described, and even in the
case of\beetroot, the farm always loses the nitrogen
which the animal dissipates in the elementary state,
and the universal salts contained in the cattle exported.

A system, from which these losses were banished,
would be the crown of the old method. It is colza
that furnishes it.

Its seed contains oil, a product of great value, and,
like sugar, composed of carbon, oxygen, and hydrogen.
Imagine an estate exclusively devoted to the cultiva-
tion of colza, and that an oil-mill is attached to it.
The oil will be exported, and will yield returns in
cash ; all the rest, stems and oil-cake, will be returned
to the soil without even passing through the medium
of cattle. To this end we must add to the extraction
of soil by pressure, a supplementary extraction by
solution. The oil-cake, upon being removed from the
hydraulic press, still contains 14 per 100 of oil, and
sells at 6s. 6d. the ewt. The oil alone which they
contain possesses this value. The substance of the
oil-cake is thus gratuitously lost to the farm. When
the oil is extracted by an appropriate solvent, sulphide
of carbon, for example, in closed apparatus, constructed
in such manner that a small quantity of this liquid
put in circulation may exhaust considerable masses of
it, there will remain a dry and pulverulent oil-cake,

96

containing all the products extracted from the soil.
They are mixed with the stems on the dungheap, and
water is added. Putrefaction soon sets in, and we ob-
tain an excellent manure, which restores to the soil
the whole of the elements which the crops had re-
moved from it, and which received the benefit of all
the nitrogen derived from the atmosphere.

After having discovered by what series of compen-
sations the practice of the past arrived at conforming
to the superior laws of vegetable production — laws of
which it knew nothing —science may even imagine a
simpler system, from which animals, and the loss they
cause, are excluded, and which, yielding important
profits, while enriching the soil, presents itself as the
last degree of perfection to which it is possible to
arrive by the methods of the past.

But the fertility of the principles I have explained
do not stop there. We must now abolish the practices
pointed out to you, and replace them by a simpler agri-
culture, more mistress of itself, and more remunerative.
Instead of compelling ourselves by infinite cares and
precautions to maintain the fertility of the soil, we re-
constitute it, in every respect, by means of the four
agents which I have pointed out, and which we can
derive from the great stores of nature. Then no rota-
tion of crops is necessary, no cattle, no particular choice
in cultivation. We produce at will, sugar or oil, meat
or bread, according as it best serves our interest. We
export without the least fear the whole of the products

97

of our fields, if we see our advantage in so doing.
We cultivate the same plant upon the same soil, in-
definitely, if we find a good market for the produce.
In a word, the soil is to us in future merely a medium
of production, in which we convert at pleasure the four
agents in the formation of vegetables into this or that
crop which it suits us to‘produce. We are restrained
only by a single necessity: to maintain at the disposal
of our crops these four elements in sufficient propor-
tion, so that they may always obtain the quantity their
organization demands.

Let us see to what point this condition is fulfilled
in our new methods. To this end, it will be sufficient
to compare the composition of the crops obtained
from the farm at Vincennes with that of a complete
manure.

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You perceive, Gentlemen, that our new system satis-
fies the law of equilibrium as well as the systems of

in our

only, we hold the balance i

the past

tends to rise, we

one of the scales
restore the equilibrium by loading the other with an

ion as
equal weight.

in proport

99

In the old systems, in which we maintained the
equilibrium blindly, it frequently happened that one
of the useful elements partially failed, and that the
crops were also deficient. With the new processes, the
plants, finding in abundance all they require, always
attain their maximum of possible development; the
crops are also much more abundant, as may be seen by
the following table.

POWER OF THE PRODUCTION OF THE OLD PRO-
CESSES OF CULTIVATION COMPARED WITH
THOSE OF THE NEW SYSTEM.

Yield per Acre.

aa a ee a ea
Old Processes. New Processes,
Straw.. .8.250 Straw...... 20.200
Wheat 11.889 23.520
\ Grain.. .3.639 GFA. « 8.250
Straw...5.414 Sikaweee ee 10,014
Peas 7.610 12.863
Grain.. .2.196 Grain...) 2.849
Beetroot Roots......... 6.978 ROO Es Asoo ae onto 20.110

But it is not sufficient to indicate the means of
producing abundant crops; we must also show the
method to be followed in order to obtain them econo-
mically.

The application of complete manures creates fertility
everywhere ; but it is not everywhere nor always neces-
sary to have recourse to so expensive a compound.

When we suppress any of the constituent agents —
the nitrogenous matters, for example — the yield of

100

wheat immediately undergoes a considerable reduction,
but that of peas and vegetables is not affected by it.
Suppress, on the contrary, the potassa: then the yield
of the vegetables suffers most. For furnips, parsnips,
and roots generally, it is the suppression of phosphate
of lime which produces the worst effects. These results
lead us to admit that among the four agents in each
kind of crop there is one which exercises a more par-
ticular influence upon the yield.

We therefore formularize the following law, which
will regulate the new agricultural practice.

Although the presence of the four agents of fertility
in the soil is necessary and indispensable for all plants,
the exigencies of various cultivations are not the same
with regard to the quantities of each of these agents —
or in other words, each crop has its leading one.

Thus, nitrogenous matter is the dominant agent for
wheat and beetroots, potash for vegetables, phosphate
of lime for roots, &c.

Suppose we undertake the cultivation of a piece of
poor land. We begin by giving it the complete ma-
nure, in order to create a sufficient provision of the four
agents of fertility. We raise one or two crops of cereals
upon this manure: then we continue the culture by
giving to the soil, each year, the dominant element of
the crop we propose to raise.

If we adopt a rotation of four years with such crops
that, at the end, has received the four agents, we can
continue thus indefinitely without ever requiring the

101

complete manure. The same system is applicable toa
fertile soil; only we may dispense with the first dose
of complete manure, and commence immediately by the
dominant element of the first crop we desire to raise.

If, on the contrary, it be desired to continue the
same crop indefinitely, we content ourselves generally
with the employment of its dominant; but taking care
to resume the application of the complete manure, imme-
diately that a slight reduction in the weight of the
crop points out the necessity for so doing.

By these simple combinations we are in possession
of a new agriculture, immeasurably more powerful than
its predecessor.

Formerly, the total matter placed by nature at the
disposal of organized beings like ourselves, had its
limits. All that the systems in vogue could do, was to
maintain it; but none succeeded in increasing it.

With regard to the problems of life and population,
human power encounters an impassable limit. The
new processes of cultivation will have the effect of sup-
pressing this barrier. Under their influences matters
at present without value, which scarcely serve as mate-
rials of construction, and of which nature possesses
inexhaustible stores, can be converted into vegetable
products : — forage to nourish the animals upon which
we feed; and cereals, to produce bread, the most valu-
able of our resources. From this, the great stream of
organized matter which sustains every existence will
be increased with new waves, and the level of life will

102

continue unceasingly to rise to the surface of the
globe.

But, Gentlemen, beneath these great results which
present themselves to the philosophic mind, there are
others, more immediate, more practical —if I may 30
express myself, — which the system I strive to make
prevail also carries on its flanks.

Since the Revolution of 1789, the territory of France
has continually been parcelled out in smaller portions.
This fact has often been proclaimed; but the evil still
continues unremedied.

According to official returns, the superficial area of
France is now divided as follows : —

Mean Surface Corresponding

Nature of the Property.

Extent. occupied. Population.

Acres. Acres.
Large Estates....... 415 43,320,000 1,000,000
Medium Estates. ... 87.50 19,250,000 1,000,000
Small Estates...... 35 16,800,000 2,400,000
Very small Estates. . 8.62 36,130,000 19,500,000
TQRATB: (0's 6a. os | 115,500,000 24,000,000

Of the one hundred and fifteen millions of acres of
cultivated land, there are thirty-six millions, possessed
by proprietors whose estates do not exceed eight and a
half acres in extent. What kind of agricultural sys-

108

tem can a man pursue who: possesses only eight acres
for every thing, and who requires as much for the sup-
port of his family ? How, and with what, will he obtain
manure? He can have neither meadows nor cattle..
He must necessarily farm badly; his land is fatally
condemned to sterility, and himself to poverty.

To combine the agents of fertility which have re-
posed in geological strata since the foundations of the
earth were laid, to place them at the disposal of the
small farmer, will be to give fertility to fifty millions
of acres devoted to the small and minimum cultivation,
and create prosperity among twenty out of the twenty-
four millions occupied in agricultural industry.

Now I ask you, Gentlemen, if these views are not
superior to the finest dreams of charity and philan-
thropy? Would they not also, if they were merely in
the condition of scientific conceptions, suffice to excite
our zeal? But experience has returned its verdict.
The crops you have before your eyes prove that with a
manure, averaging in cost about five pounds a year, it
is possible to obtain abundant harvests. Reduce, if
you will, the excess of production, per acre, to a ton,
which is here raised above three tons; and applying
this data to the fifty millions of badly cultivated acres,
and see to what financial results we shall be inevit-
ably led.

The first movement in this direction will create a
demand for fertilizing materials to the extent of some
millions. What an impulse this must give to com-
merece !

104°

Next to obtain twenty millions of tons more wheat
than French agriculture supplies at the present time,
and consequently an increase of wealth of about five
millions sterling. What a guaranty against famine!

What is required to accomplish such a revolution ?
We must apply the principles I have explained to you,
and generalize them. In the second place, commerce
must place the agents of fertility under the protection of
new institutions of credit. They must be so conceived
that the advances for the necessary manures may be
made to the small farmer, to be repaid out of the ex-
cess of crops derived from the fertilizers.

The solution of this problem connects itself in a sin-
gular manner with social and political destinies. Every-
where the approach of democracy manifests itself. Is
this a good? Is it an evil? I am not competent to de-
cide the question: but it is very certain that at the
present time the greater part of agricultural population
deserts the country to seek an easier condition of life in
the cities.

This immense class, second only to the working pop-
ulation of the cities, represents, in a high dégree, the
true public spirit.

To change its economic situation, to put it into a
condition of more intensive cultivation, notwithstanding
the exigences of the scale upon which it operates, is to
attach it tq the soil by its own interests. By this
means a large conservative party may be created, with-
out which a democracy based upon commerce will grow

105

up, leading only to a crisis analagous to that which now
presents so deplorable a spectacle in America.

England has avoided this danger at the price of an
enlightened and patriotic aristocracy, but whose exist-
ence perpetuates an inequality in human destinies
which conscience repudiates and the laws of humanity
condemn. Neither England nor America, therefore,
have solved the problem of a powerful, wise, and just
democracy.

To me, it seems that our beautiful country is pre-
destined to give this great example to the rest of the
world, and I have the firm hope that the principles I
have placed before you, in the course of these lectures,
will serve as the starting point to the realization of this
inestimable result.

APPENDIX.

EXPERIMENTAL FARM AT VINCENNES.
HARVEST OF 1864. |

On the 31st of July, M. George Ville reaped and
thrashed his crops in presence of a large concourse of
agriculturists. The results were as follows: —

Wueat:— Third Crop from the same land without fresh manure
since the first application.

Crop per Acre. Without Manure. With Complete Manure.
PGE oo ess), ‘nce Se OORIB., o's ope ices SOA EBS
Rt otha, ts) +) is Cake oe iam ce ue te nok, Mee

Oba iS cwivts 0.808 TB. 30.410 kat QO LE

WHEAT: — Fourth Crop without Fresh Manure since the first.

Crop per Acre. Without Manure. With Complete Manure.
PW, Vie | eee tee AOR ADEE ys 4) ie ie eels
REN he tage ca Sele) NS Oe: Ite, bre cee ee EO ee

otal és A890 bass. 0s et eae:

CoLtza:— Coming after two Crops of Barley without fresh Manure.

Crop per Acre. Without Manure. With Complete Manure.
Straw and Silicates . 5.682 Ibs... . . . 7.700 Ibs.
Merino iar Peete 6, ye a RN TR oo eee ena

eae a —_

Total, | ="... .. 26.962 dhs... ics ye AO:

107

CROPS OF 1864.—BEETROOT.

On the 30th of October the crop of Beetroots was
publicly got in. The results obtained were as fol-
‘low: —

1. Som wirHout MANURE.

Crop per Acre.

WECB VSS tira oe Meee ell ca vives a htaley See OM Ere
Roots Bay ah Mie CN ie oe Dae ume aa «TI Ge Erato
Mo talie ls. ue ech s Pee ACL Se

This piece of land, put under cultivation in 1861, had previously
yielded two crops.

In 1861. In 1862.

Crop per Acre.

Leaves... . . 14:696:Ibs Leaves... 9: . «. »7.0400ibs:
Roots! vec d on > 0) 44.616. * Roctenke, 8s 1205 6a

59.312 Ibs. 19.096 lbs.

In 1868 the crops were devoured by the white worm,
consequently there was no return, and this year’s crop
was a little increased by the preceding year being
fallow : —

2. Som with CoMPLETE MANURE.

Crop per Acre.

IRGAV ESRI eet okies dete in ee es 6.618 lbs.
Roots rE Wnty estar? Ub Meee Ney Ys NETO] WALL
31.608 Ibs.

This piece of land, like the preceding, had furnished two previous
crops since it received any manure.

108

In 1861. In 1862.
Crop per Acre.
Leaves. . . . 14.344 Ibs. Leaves. . = « $-680Ibs.

ROO. s ciests a). 41,000" © Roots >... «>» 21.8208
62.304 Ibs. 81.500 Ibs.

8. LAND wiTH CoMPLETE MANURE, but which has received acid
phosphate of lime instead of ordinary phosphate.

TGCAVESIOE cl Meic ells Ponte tent) WeOO bse
Roots Bi igh el oe ie Me toe Meee ne Os aAies

38.324 lbs.

This piece of land had also yielded two crops previous, since it had
received any manure.

In 1861. In 1862.
Crop per Acre.
eaves). °. . . 15.488.1bs. Leaves’.::. < . 11.000 Tbs.

odisayoe: 6. T8786. Rootes s/s .s as (Sa Gearte
94.275 lbs. 44.968 lbs.

‘

4. LAND witH COMPLETE MANURE.— Crop of Beetroot coming
after three fine crops of Wheat without fresh manure.

Crop per Acre.

BWeaVOSmibitccke te <ecis eis tisten measeO4 IDs:
POOLS eeice ee hers Pn ey Cellet eee BOs Sao tuee

44.130 Ibs.

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