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LETTERS

ON

MODERN AGRICULTURE,

BY

BATON’ VON LIEBIG.

Epvitrep sy JOHN BLYTH, M.D.,

PROFESSOR OF CHEMISTRY, QUEEN’S COLLEGE, CORK,

WITH ADDENDA,
BY A PRACTICAL AGRICULTURIST.

EMBRACING VALUABLE SUGGESTIONS, ADAPTED TO THE WANTS OF
AMERICAN FARMERS.

NEW YORK:
JOHN WILEY, 56 WALKER STREET.
1859.

Entered, according to Act of Congress, in the year 1859, by
JOHN WILEY,

in the Clerk’s Office of the District Court of the United States for the Southern
District of New York.

<1 £&- & R. CRAIGHEAD,
Stereotyper and Electrotyper,
Carton Building,
81, 83, and 85 Centre Street.

TO

HIS MAJESTY MAXIMILIAN II.

KING OF BAVARIA.

—— 0 ———

To the circle of men devoted to Art and Science, whom
Your Majesty assembled around you last winter, for the
purpose of obtaining from their discourses and_ their
animated interchange of opinions a reflection of the intel-
lectual movement of the age, I am in a great measure in-
debted for the impulse which led to the researches to which

these Letters on Modern Agriculture owe their origin.

If, therefore, I venture, with the most profound respect, to
dedicate to Your Majesty, who takes the same kind and
active interest in the practical life of the nation and its wel-
fare, as in science and its progress, this Work, which is in-
tended to bring about the union of the natural sciences with

agriculture, and to effect their beneficial co-operation, I do

lv DEDICATION.

so in grateful remembrance of the active and powerful
interest which Your Majesty has deigned to take in the
labours of
Your Majesty’s
Most obedient humble Servant,

JUSTUS VON LIEBIG.
MonicH, April 2, 1859.

EDITOR'S PREFACE.

=,

THESE important and interesting Letters on ‘“ Modern
Agriculture” are addressed by Baron Liebig, not to agri-
culturists alone, but to every one who takes an interest in
the welfare of his country.

The wants of an increasing population, and the danger
of a possible stoppage, at any moment, of supplies drawn
from foreign sources, make all feel a deep interest in the
“discovery of the means of producing more bread and
meat on a given surface.” Landed proprietors, practical
agriculturists, and men of science, have all of late years
devoted their united energies to solve this important pro-
blem. From the efforts of so many anxious labourers, as
might be expected, a corresponding harvest of practical
results has been obtained. The author, who has for years
occupied himself with the elucidation of the laws of the

nutrition of plants, passes in review, in these Letters, the

vi EDITOR’S PREFACE.

mass of practical facts thus acquired, and by the light of
science endeavours to give them their true import, and to
deduce from them fundamental laws of general application
in agriculture.

It is not long since the humus theory occupied every
work on agriculture, and the fertility of our fields was
described as entirely dependent on the presence of this
supposed valuable substance. The real nature of humus
is, however, now understood, as well as the conditions
under which alone it can prove valuable in the nutrition
of plants.

It is also now well known, that plants cannot grow and
attain complete development, without the simultaneous
action of atmospheric food and certain mineral elements,
which are absolutely indispensable to their existence. The
author has in these Letters shown, that no single element
of these indispensable mineral matters possesses superiority
over another, but that they are all of equal value to the
life of a plant. Hence, if one of them be absent in the
soil, a fully developed plant cannot be produced by the
others, until the deficient element be supplied. But from
the importance of this deficient element in a given case,
we are not entitled to infer its equal efficiency in other

cases, where the same conditions may not exist;—and yet,

EDITOR’S PREFACE. Vil

this fallacy lies at the root of many of the practical opera-
tions of agriculture.

The author points out the nature of this fallacy, and in
the discussion of this subject, brings forward new and
important facts connected with the nutrition of plants, and
with the mode of action of some special manures. The
-mineral food of plants is shown by him to exist in the soil
in two different states; in the one, it is immediately avail-
able; in the other, it is not yet brought by decomposition
into a condition for absorption by the roots. In every case
the produce of a field and the duration of its fertility bear
a fixed relation to the sum of the available food in the
soil. Hence, if by mechanical or chemical means applied
to the soil, we render the absorption of this food by plants
more rapid, we thereby increase the amount of produce in
a given time, and thus more quickly exhaust the stock.
At the end of this given time the field will, for agricul-
tural purposes, be unproductive, if the mineral matters
removed by the crops be not restored.

The author directs attention to the fact, that this funda-
mental principle has been lost sight of in some of the
systems of modern high farming, which have been based
on the assumption that the available mineral food of plants

in arable soils is inexhaustible. He urgently points out

Vill EDITOR’S PREFACE.

that in stimulating the productiveness of our fields by a
system of high farming, without at the same time restoring
all the mineral matter removed, the present occupiers of
the land may rejoice in their abundant crops, but the in-
evitable result of this system will be the ultimate exhaus-
tion of the soil.

The editor has endeavoured in this translation to convey
to the reader as faithful a transcript as possible of Baron
Liebig’s views; and accuracy has been further insured by
the revision of the proofs by the author. In conclusion,
the editor begs to acknowledge the kind assistance of his
friend Dr. Hofmann, from whom he has received many
valuable suggestions whilst the sheets were passing through

the press.

JOHN BLYTH.

QUEEN’s COLLEGE, CORK,
April 2, 1859.

PREFACE.

THE state of matters to which the contents of these Let-
ters refer, exists in feality in Germany alone; and I should
be taking an erroneous view of the actual position of Bri-
tish agriculturists, were I to attribute to them the leading
views entertained by German and perhaps French agricul-
turists. These letters must therefore be regarded as a mir-
ror in which the scientific principles already established,
and certain erroneous doctrines prevailing in practice are
reflected side by side; and each individual must be left to
draw his own conclusions, on comparing his own acts with
the standard thus furnished him.

Upon the whole, English agriculture, as a rule, is based
on the same spoliation system which exists elsewhere ; for
though some certainly pursue a rational system, there are
but too many who act otherwise.

The remarks which I have made on writers on agricul-
ture and on agricultural training schools, must be received,
- in like manner, with the same limitation. I am too little
acquainted with the English agricultural institutions to
pass judgment upon them, and my strictures can only be

x PREFACE.

regarded as applying to those of Germany. With respect
to the English agricultural chemists, I also readily ac-
knowledge that Thos. Way, Professor Hodges, and others,
have by their researches rendered the greatest service to
agriculture,

I cannot, however, concur in opinion with those who
would base all progress in agriculture upon elementary
analysis and on other useless chemical operations; nor
with those who forget that such progress results only from
the investigation of scientific laws, and from a correct com-
prehension of the facts observed,—things that cannot, like
products in a manufactory, be procured wholesale by a
mere outlay of capital and by a course of experiments.

The great progress made in agriculture, since the end of
last century, has been essentially confined to improvements
in the practical part, by which I here mean to designate
the technical operations of farming; but these improve-
ments have paved the way for the new and higher develop-
ment of the present day. It is in the nature of things, that
in all technical pursuits, and more especially in agriculture,
the perfecting of the practice should precede the effective
application of scientific principles. So long as the man
engaged in a technical pursuit finds that there is still ad-
vantage to be derived from improvements in the manage-
ment of his business, he will not trouble himself with other
matters. But by improvements in the practice, or in the
management of his business, everything desirable is not
attained ; the practical operations in themselves give him

PREFACE. Xi

no insight into his own acts, nor a reliable standard for the
value of his observations and experience: at last he will
not permit himself to be swayed by the customary mode
of proceeding. It is now that he turns to science to satisfy
his requirements.

As generally happens in the period of transition into «
new state of things, a conflict has of late years been carried
on between practice and science; the former was unable
to deal properly with the unwonted resources placed at its
disposal by the latter; and it is easy to account for the
cause of this conflict.

If, in fact, a person of the educated classes, who is not
an agriculturist, were to peruse the agricultural works and
journals that have appeared of late years, he would find
that the preponderating majority of agricultural writers
are quite agreed on this one point, that the views which I
have put forward on agriculture, have no practical value,
and must be looked upon as in part refuted. They main-
tain that experience, which is older than science, has long
since taught the practical man what is needful for him;
that the result proves his system of cultivation to be the
best suited to existing circumstances; and that his abun-
dant and increasing crops are irrefragable proofs of the
soundness of the views which guide his practice.

These expressions and opinions are not generally appli-
cable and valid; they are not, however, groundless. The
agricultural literature in which these views are put for-
ward, exists in reality only for the class of thriving agri-

Xi PREFACE.

culturists who are in a position to buy and possess agricul-
tural manuals and journals; and it is evident, that the
literature will reflect the requirements, the wishes, and the
practice of these agriculturists to whom it owes its exist-
ence. It is not in the nature of things that it should be
otherwise. As a rule, an agriculturist of this class is a
producer of flesh and corn, and is generally possessed of a
good property and plenty of capital; his fields comprise
meadows and arable land; he keeps a large stock of cattle,
produces plenty of farm-yard manure, and is not sparing
in its use. If he happens to be short of manure, he has, at
all events, money to buy guano, Chili-saltpetre, bone, earth,
and rape-dust. He knows the value of farm-yard manure
and of the supplementary manures just named, and how
to use them to the best advantage. His steward attends to
the rotation of crops which has been permanently fixed
upon, and to the application of manure at the proper sea-
son,—things which do not require the teachings of science ;
he has to be guided, he tells you, by other circumstances
which give him quite trouble enough.

The wealthy landed proprietor is an educated man who
has certain intellectual wants. Agricultural literature satis-
fies these. The writer on agriculture endeavours to prove,
by theoretical reasoning, the excellence of empirical prac-
tice ; he defends the views of the practical man, and strives
to invest them with the authority of science. Even if the
explanations are at times in complete opposition to un-
doubted truths, they have at all events this much in their

PREFACE, Xi

favour, viz., that the agriculturist believes them to be ia
accordance with his own experience; and, indeed, the ob-
ject of the writer does not extend beyond securing the
satisfaction of the practical man, by showing what is termed
the agreement of the practice of agriculture with the the-
ory. ‘Thus, for instance, in the production of corn and
flesh, the alkalies in the farm-yard manure remain in the
field, and in the progress of cultivation their quantity ra-
ther increases than diminishes; a restoration of these alka-
lies is therefore not required, and would often be super-
fluous. This circumstance, which arises from the kind of
crop grown, the writer explains to the practical man to be
the result of the nature of his soil; he informs him that
there is no necessity to restore the alkalies removed, be-
cause his soil contains an inexhaustible quantity of them.
It is true that this statement is directly opposed to all that
Chemistry teaches; but then it is a matter of indifference
whether or not the soil is inexhaustible, if the main point
be made out, viz., that there is no compensation of these
matters required from without by purchase, &c.

The writer on agriculture further informs the practical
man, why guano and other manures used in aid of farm-
yard manure are so beneficial. It is clear, he says, that all
these matters contain in the nitrogen a constituent common
to all of them; and as the employment of each is attended
by a similar result, viz., by a corresponding increase in the
amount of produce, it is obvious that the effect must be
attributed to one and the same cause in all. The practical

X1V PREFACE.

man is told that in the corn and flesh produced on his land
he removes nitrogen ; that the exhaustion of the soil is the
consequence of this removal; and that, of course, by re-
placing this nitrogen, the productiveness of his fields is
restored. ‘To question the fact of the restoration of fertility
to land by guano, bone-dust, or rape-dust, would be an act
of great folly, for this fact is borne out by the experience
of the practical man; the latter, therefore, fully accepts the
explanation offered, although there be in it only the merest
semblance of truth. He is quite satisfied with the belief
that his system of cultivation has been shown to rest on a
rational and-scientific basis; which, in reality, is not the
case.

Practical questions, such as the following: Why the
after-effects of the above-mentioned manures are not uni-
form with those of farm-yard manure, but differ so much
from them: or why clover no longer grows on many
fields; or why peas, again, yield good crops on the same
field only after long intervals: such questions as these, of
course, do not engage the attention of the agricultural wri-
ter. He speaks of such matters as if ordained by Nature ;
which cannot be altered; and for which the agriculturist
must therefore make due allowance in his system of hus-
bandry. But let the practical man only succeed—which,
however, is not likely to be the case—in solving these
questions, or in overcoming a difficulty which may have
been placed in his way by the writer himself, and the lat-
ter will at once proceed with right good will to prove te

PREFACE. XV

him by a series of chemical analyses the intimate relation
between theory and practice.

These precepts of agricultural writers do no harm to the
agriculturists for whom they are intended. These indi-
viduals maintain their fields in a permanent state of fer-
tility, by means of farm-yard manure, or by the purchase
of guano and other manuring agents; their simple system
of cultivation affords no room for exhaustion of the soil.
Whatever constituents they remove from the land in the
form of corn and flesh, they replace completely, and even
in eXcess.

Although scientific doctrines play a very subordinate
part in the system of cultivation pursued by these fortu-
nate landed proprietors, inasmuch as their entire know-
ledge consists in a few recipes which might be written upon
a card; yet it is for them that the most esteemed agricul-
tural hand-books and manuals, and the greater number of
the articles in agricultural journals are written; it is for
them that books on soils and manures are published, and
enriched with stores of scientific learning from the domains
of chemistry, physics, botany, and geognosy ; it is for their
benefit that so many chemical analyses of corn and straw,
hay and turnips, are made. They do not, indeed, read or
understand all that is written, because, in fact, there is no
intelligible meaning in it; and they are quite aware that
‘these rows of figures do not advance their business one
hair’s-breadth ; still they are delighted with all this parade
of learning, on account of the seeming deep scientific basis

xvi PREFACE.

assigned thereby to agriculture, which they follow with so
much ardour and profit.

After the wealthy landed proprietors comes a second
class of agriculturists, who possess land, but less capital
than the former. They obtain good crops by the simple
cultivation of their fields with farm-yard manure; they
purchase but a small quantity of guano, or other manuring
agents; and trusting to the theory maintained by writers
on agriculture, that their fields are inexhaustible in mineral
matters,—which is intended to apply to a different system
of cultivation from theirs,—they believe that there are no
limits to the fertility of their land. As they have as yet
observed no failure in the conditions of its fertility, they
are of opinion that it will be time enough to devise means
to meet the necessity when it occurs.

These men also read the agricultural journals, and are
quite satisfied in their own mind that the principles of
science are not suited to their system of husbandry. They
re-echo the opinions of the men of the first class, and are
warm supporters of the precepts of the writers on agricul-
ture, although the system of cultivation derived from these
teachers brings their fields every year nearer that ruin to
which they must inevitably come by following such a
system.

The resistance which science has met with on the part
of practical men belonging to this class, is partly due to
ignorance of its true principles, partly to a wrong concep-
tion and interpretation of the same.

PREFACE. XV

If I have criticised the false views and opposition of
these men, in purely chemical questions regarding the soil,
manures, and the nutrition of plants, with a severity in-
spired by sincere conviction, it must not be overlooked
that they were the aggressors in the conflict. An attack
of their views on my part would have been inexcusable ;
for, with that simplicity which characterises those who pre-
sume to judge of things they do not understand, they have
candidly avowed that chemistry and the natural sciences
are branches of knowledge unknown to them. They are
all, without exception, men deserving the esteem which
they enjoy in their social relations, and whose feelings as
individuals I could not have the most distant intention of
wounding; but when they step forward as supporters and
propagators of precepts, which have nothing to recommend
them beyond the fact that people have for half a century
pursued a system of cultivation in conformity with them ;
which are devoid of all rational basis, and are quite be-
neath the present position of chemistry and the natural
sciences,—precepts which must in process of time dry up
the sources of prosperity of the agricultural population,—I
should hold it to be a crime against the public interest
were I to be restrained by any consideration for indi-
viduals, or the position they may occupy, from laying bare
the weakness and flimsiness of their arguments, and from
exposing their total ignorance of the first principles of
chemistry and the natural sciences.

From want of a proper insight into their own pursuit,

XVI PREFACE.

these men are in their blindness the worst enemies ol
science, the objects of which they do not comprehend.

The scientific questions connected with agriculture arc,
in their consequences, of too great importance for any one
to enter upon their discussion, before he has seriously con-
sidered whether he really understands the subject.

One of the most important objects of the practical man
is to discover active manures, by the use of which barren
fields may be made productive, and the produce of fertile
fields be doubled ; but they will never be found, or only
accidentally, by seeking them blindfold in an empirical
manner. ‘The practical man does not know that for years
the study of small and apparently insignificant things must
be pursued, before the mind is prepared to grasp questions
of importance.

The method followed by science in seeking out active
manures is very different, much more toilsome, but more
certain. It is rendered doubly difficult from the fact, that
the man of science who adopts it has not only to combat
the erroneous notions prevailing in the domain of practice,
but also the errors of his own science, which have their
influence over him, and may cause him at times to make a
false step; but he knows that the path leading to light is
thorny and dark, and the perception of an error is in itself
a victory.

The prevailing agricultural literature has nothing in the
shape of aid to offer to the small landed proprietor or far-
mer; or to him who possesses little or no capital, no good

PREFACE. xix

arable land, no meadow, an insufficient stock of cattle, and,
accordingly, little or no farm-yard manure; and those who
cultivate commercial plants, such as tobacco, hops, flax,
hemp, or the vine, find in it no information, no insight
into the nature of their pursuit, but only insufficient rules,
suited to particular localities.

Science should, however, be the common property of
all; it should bestow aid on all who require and seek it,
and should increase the intellectual store of rich and poor
who are sincerely striving after truth.

From the preceding remarks may be gathered the rea-
sons which have induced me to publish these letters on
Modern Agriculture. I am desirous to make the educated
men of the nation acquainted with the principles which
have been established by chemistry in connection with the
nutrition of plants, the conditions of the fertility of soils,
and the causes of their exhaustion. Should I be fortunate
enough to impress upon a wider circle the conviction of
the value of these principles, and of their extreme import-
ance in a national and economic point of view, I shall look
upon one of the tasks of my life as accomplished. With
the aid of the educated men to whom I address myself,
success 1s, 1n my opinion, certain; but without their assist-
ance it appears to me to be impossible.

As regards those agriculturists who oppose the teaching
of science from ignorance of its objects, I hold it of the
greatest importance to be unwearied in our efforts in direct-
ing their attention to the facts upon which scientific prin-

xx PREFACE.

ciples rest; for if we can but succeed in inducing them to
reflect on the proofs of these principles, they may be con-
sidered as converts to the doctrines of science.

The laws revealed by the study of the natural sciences
will determine the future intellectual and material progress
of countries and nations; every individual is personally
interested in the questions connected with their application.

[In conclusion, I have to state that I have been indebted
for a number of facts in Letters VI. and VII. to an excel-
lent article in ‘Chambers’s Information for the People,”
written, as I have since been informed, by R. Russell, Esq.,
Kilwhiss.

Cagyl ENTS.

19)

LETTER I.

The conflict between Science and Practical Agriculture—The foundation of
Agriculture is experience—Progress founded on experience has its limits
—The connection of Agriculture with Chemistry and the subsequent
reaction—Progress in Agriculture must be based on the Inductive Method
—False teachers of Agricultural Science—Practice based on the blind
experience of others leads to error—The rejection of scientific teaching by
practical men due to their ignorance of the real object of Science—The
solution by mere practical men of questions proposed by Agricultural
Societies cannot advance Agriculture—The rejection of all scientific
instruction by practical men only leads to self-deception............... I

LETTER II.

Present profit is the leading principle of the prevailing system of Husbandry
—This system is one of danger to Agriculture—-General view of the
Nutrition of Plants—Atmospheric and Mineral Food—The absolute neces-
sity to Plants of all the Constituents of their Mineral Food—Present

‘views of the Nutrition of Plants erroneous—Rain water does not dissolve
out the Mineral matters in the Soil—Remarkable absorbent power of Soils
for the soluble Mineral Food of Plants, and particularly for Potash, Ammo-
nia, and Phosphoric Acid—This power is limited, and varies with the Soil
—Organic matter in the Soil materially modifies this power........... 19

LETTER III.

Our cultivated plants do not receive their food from Solution—Roots of plants
derive their Nourishment only from those portions of Soil absolutely in
contact with them—This view supported by the composition of River,
Well, and Drainage water—The Roots of plants must themselves exert
some peculiar action in Nutrition—The Life of land-plants endangered by

XXil CONTENTS.

food when in Solution—In Water-plants the laws for the absorption of
Food must differ from those of Land-plants—The Ash of duck-weed shows
that plants have a Power of selecting their Food—Reason why mud from
stagnant pools is a good Manure—Remarkable power for absorbing Mois-
ture possessed by Soils—By absorption and evaporation of Moisture, the
Soil is warmed or cooled—Great importance of this fact to Vegetation—
The two Sources from which Moisture is absorbed by the Soil—Natural
Law-.dedueed from the above faQpiiaag is och sins s wis sid ss Sino tine wine 30

LETTER IV.

The Belief in the value of Humus no longer exists; its Action now ascertained
—Effect of the Salts of Ammonia not dependent on their Nitrogen—The
action of Nitrates like that of the Salts of Ammonia—Experiments with
Nitrates and Chlorides—Experiments with Salts of Ammonia alone, and
with the addition of Common Salt—Solubility of the Earthy Phosphates in
solutions of Chlorides of Ammonium and of Sodium, and of Nitrate of Soda
—Experiments with these Salts—Their Solvent Action similar to that of
Carbonic Acid water—The Salts of Ammonia are decomposed in the soil ;
their twofold action—Difference in the Comportment of Salts of Potash and
of Soda in the Soil—Potash extracted by Sulphate of Ammonia from silicates
—Application of the Action of Chili Saltpetre, Salts of Ammonia, and
Chloride of Sodium to explain the increase of fertility in the soil, and the
Nutrition of Plants.......... pb igicint ad ims # ch emi Jan. enh sweeten

LETTER V.

No free Ammonia in the Soil—The amount of Food obtained from the soil
by plants is in proportion to the absorbent Root-surface—The early deve-
lopment of Roots due to the accumulation of Nourishment in the surface
soil—Estimations of the quantity of Ammonia in our cultivated fields—A
deficient crop not due to the Absence of Ammonia in the soil—Experi-
ments with salts of Ammonia; the crops only slightly increased thereby—
Increase of produce due to accompanying Minerals ~Experiments of Lawes
and Kuhlmann with salts of Ammonia, &c.—The fertility of a field depend-
ent on the sum of the Mineral matters in it—The activity of these Minerals
increased within a given time by the Salts of Ammonia—The soil more
rapidly exhausted by their use unless there is a restoration to it of the
removed. Mineral matters: ..,... . ajc «4.6096 pe sae apie ee

LETTER VI.

The Amount of Carbonic Acid and Ammonia in the Air—The Balance of
Organic Life—The Absorption and Assimilation of Food differs in Perennial

CONTENTS. Xxill

and in Annual Plants—The mode of Growth of Perennial, Annual, and
Meadow Plants—The quantity of Nitrogen in different Crops—Advantages
of Nitrogenous Manures to Cereals is not in consequence of the failure of
Nitrogen from Natural Sources—Organie and Nitrogenous Manures useful
in Annual Plants with small absorbent Leaf and Root-surface—Effect of
Nitrogenous Manures less marked in plants with large Leaf-surface—
Supply of Ammonia in Manure not necessary to all Plants—Green Crops
condense Ammonia from Natural Sources, and supply it in the excrement
of animals to Corn-fields—The Nitrogen of Manures is thus indirectly
obtained from the Air—The total quantity of Nitrogen from a manured
Corn-field is not greater than from anunmanured meadow, but more time
is required by the latter to collect it—Explanation of the good effect of
Nitrogenised Manures on Annual Plants with small Leaf and Root-
Burewed ss 25f5tiis: Lh LEAS we SSE4es Rese Merwe oe wae Savane owen ey es 69

LETTER VIL.

Salts of Ammonia increase the number of Roots and Leaves in the first period
of the Growth of Plants; hence the superior action of these salts in Spring
—Circumstances which modify the production of Leaves, Flowers, and Roots
—Circumstances under which Nitrogenous and Concentrated Manures are
useful—Causes of the failure of plants continuously grown on the same Soil
—Food of plants when too concentrated often exerts a deleterious Chemical
action—Provision in the Soil to prevent this action—Properties of Soils
altered in cultivation by the removal of Mineral Matters from them, and by
the increase of Organic Matters in them—The increase of Organic Matter
frequently a cause of Disease—Finger and Toe disease; its cure—Excess
of soluble Silica and of hurtful Organic Matter in soils removed by Lime—
Noxious Organic Matters arising from the continuous growth of Perennial
Plants on Meadows removed by Irrigation....... waa 4 Py wide amaealgies 80

LETTER VIII.

The food of Land Plants is not absorbed by the roots from Solution, but from
the Soil directly in contact with them—Hence the necessity for a uniform
distribution of the food of plants in the soil, and for the great Ramification
of their Roots—A field with much mineral food may be comparatively
unproductive if it is not thoroughly mixed with the Soil—The roots of a
crop diminish the mineral food in those portions of the soil in contact with
them—Fertility is restored to those portions by ploughing and other
mechanical means, which mix the soil and allow the roots to ramify freely
—Reason of the value of Green Manures—Estimation of amount of mine-
ral food in the soil to produce different Remunerative Crops—Law of
Exhaustion in soils for different crops—Action of organic remains in the

XXIV CONTENTS.

soil on the mineral constituents—Progress of diminution in Grain and Straw
of cultivated crops, when the Ash Constituents are not restored to the soil,
and when those of the straw alone are returned—Relation between the pro-
duction of Leaves and of Grain—Relative proportions of mineral food
required for Grain and for Root or Leaf-producing crops—The increase of
Organic matter and Nitrogen in the soil by Green Crops, without the
addition of mineral food, augments the produce of grain, but hastens the
period of Exhaustion of the soil—Progress of the exhaustion of a soil by
the cultivation of shallow and of deep rooting plants—The manner in which
the Subsoil contributes to the prolongation of the fertility of land—
Importance of the formation of large roots after germination—Exhausted
fields in an agricultural sense—Fertility restored by manures—The nature
of Manures—The part played by the Organic and Inorganic Matter of
Manures—Farm-yard Manure............eeeceeees oo 92 tae aE

LETTER IX.

constant relation between the Sulphur and Nitrogen of Organic Compounds
and the Alkaline Phosphates and Alkaline Karths of Cereals and Legu-
minous plants—Mineral substances are as indispensable to the Life of
Animals as to that of Plants—The amount of Phosphoric Acid and of
Potash ascertained by analysis as existing in Soils is very small—The
errors of Practical Teachers proved from the writings of Practical Agri-
culturists—Fertility of land cannot be maintained by Nitrogenous and
Carbonaceous Manures alone, but by the Restoration of the Ash Constitu-
ents of Plants—Critical examination of the views of Walz, a practical ~
teacher, on the Nutrition of Plants—The mineral food of plants in arable
soils is not inexhaustible—The volatile and organic matters of Manures
are not the most important—The nature of Guano and its active con-
SETUOMIB 5% rai 5 He eies were shainereta ee eltia we dive WORD Wie ee lane a a

LETTER X.

The empirical agriculturist is a trader—The duties of the empirical and
rational agriculturist— Views of Albrecht Block—Rotation of crops not un-
important; an underground crop is followed by a better cereal—Cropping
of land without manure, and the removal of produce, cause exkaustion—
The spoliation system of agriculture—Exhaustion of the lands in North
America by this system—Exhaustion of the Minas Geraes fields—High
farming is a more subtle system of spoliation of the soil—Mutual relation
of clover, turnip, and corn crops; and the results of removing from the
lands the mineral constituents of these crops respectively—The German
system of farming before the Thirty Years’ War—The German three-field

CONTENTS. XXV

system of rotation—Introduction of clover cultivation into Germany—
Opposition to its introduction—False teaching in connection with the value
of manures oe @ eee eereeeee ee ee ee ee Saaeate iso oe aie ear eae 138

LETTER XI.

Ammonia is an element of food indispensable to Plants—Comparison of the
action of Water and Ammonia—Ammonia is an element of food and a
Solvent of Mineral Matters in the Soil—Ammonia alone, or its Salts, useless
to Plants, without Mineral Food—Vast amount of Ammonia in arable Soils
—The “Nitrogen” theory of Manures—The error of attributing the chief
value of a Manure to its Nitrogen—The reason why the quantity of Nitro-
gen in Guano and Excrements may be taken as a standard of their Agri-
cultural value—Proper mode of Comparing the relative effects of Guano,
Ground Bones, and Chili-saltpetre—The Loss of Fertilising matter in the
Flesh and Grain carried to large towns; the constant loss of Phosphates in
the Excrements of the inhabitants—The importation of Guano most
inadequate to replace this loss—Superiority of Human Excrement over
Guano asa Manure for Corn Fields—Tobacco, Potatoes, and Beet-root are
more exhausting to a soil than Wheat—Injurious influence of extensive
Cultivation of the Vine on the production of Corn and Wheat—Effect of
the.Subdiviaion: of the Land ....:4.:5 2/045 «)ss0 a0 secsie a ian iia ca ek Si 165

LETTER XII.

Modern Agriculture has no history—The reason of this—The history of
Roman Agriculture shows the existence of the spoliation system at that
period—The works of Cato, Virgil, Varro, and Pliny inculcate, two thou-
sand years ago, the same precepts that are now taught by many teachers
of agriculture—Quotations from these writers, to show their opinions on
the exhaustion of the ground; on the different kinds of soils, and the
modes of improving them; on the selection of plants for the soils which
are suitable for them; on fallowing; on the cultivation of green crops for
manures; on the different kinds of manure and their relative values, and
modes of managing them—The various precepts inculcated of old only
hastened the ruin of Roman agriculture.......... OP ee eS 187

LETTER XU.

The true object to be kept in view in estavlishing Scientific Principles—In
. scientific agriculture, ‘‘ Manure,” like the term “ Phlogiston,” has no longer
a meaning—The cultivation of Green Crops for the purpose of keeping a
stock of Cattle for manure is not necessary in the cultivation of land—The
distinction between the Necessity and the Utility of keeping cattlk—No

XXVvl1 CONTENTS.

necessary conuection exists between the production of Corn, and that oi
Flesh and Cheese—The fundamental principles of German Agriculture
quite unknown in China—Chinese Agriculture—The manures employed
by them—Great value set by Chinese on human excrements; their mode
of collecting and using them—Chinese compost—Their mode of sowing
_and transplanting wheat—Plants cultivated as green manure for rice fields
—tThe lesson taught by the Chinese system of agriculture............196

LETTER XIV.

The law of Compensation is of universal application—Elementary information
on Chemical subjects connected with Agriculture easily imparted—Im-
portance of instructing youth at school in these fundamental truths—Theo-
retical instructions should always precede Practical—The proper mode of
instructing agriculturists in the Theory and Practice of Agriculture—The
present constitution of Agricultural institutions very defective—The false
position of Science in practical agriculture is the result of the teachings of
these Schools—The demands made by Science on agriculturists are simple,
and a knowledge of them cannot prove injurious—Science demands that
agriculturists should test the Truths she advances—The truths in these
Letters expressed by a Formula—The value of Guano first discovered by
Science—The establishment of Reservoirs for animal excreta strongly
recommended— Reliance to be placed upon such Excreta rather than on
Guano—Chemistry can only help agriculturists after they have exhausted
all the means at their disposal—Notes on supply of guano and on the
agriculture of Tuscany......... vin eaate alk apa scene

A PICs sw panne wip we ue weak ee err eee

LETTERS

ON

THEORETICAL AND PRACTICAL AGRICULTURE.

LETTER I.

The conflict between Science and Practical Agriculture—The foundation of
Agriculture is experience—Progress founded on experience has its limits
—The connection of Agriculture with Chemistry and the subsequent
reaction—Progress in Agriculture must be based on the Inductive Method
—False teachers of Agricultural Science—Practice based on the blind
experience of others leads to error—The rejection of scientific teaching by
practical men due to their ignorance of the real object of Science—The
solution by mere practical men of questions proposed by Agricultural
Societies cannot advance Agriculture—The rejection of all scientific
instruction by practical men only leads to self-deception.

THE present conflict between practical agriculture and
scientific Chemistry, carried on by one party with some
animosity and passion, perhaps to the ultimate advantage
of the question at issue, might justly claim the attention
of enlightened statesmen; for it concerns the weightiest
material interests and the fundamental prosperity of the
state. The most urgent problem which the present day
has to solve, is the discovery of the means of producing
more bread and meat? on a given surface, to supply the
wants of a continually increasing population. The most

Notr.—tThe superior figures in the text refer to the treatment of the sub-
jects in the Addenda.
1

2 THEORETICAL AND PRACTICAL AGRICULTURE.

important social questions are bound up in this problem,
which science is expected to solve.

Science has in her own way made the necessary prepara-
tions for its solution, but her way does not please practical
men. From them she has met with no support, but with
opposition in almost every thing she has done. |

For the new building, which is to give room and shelter
to all who will enter, science has levelled the ground; she
has drained it, and driven piles into the swamp, to insure
a firm foundation; she has indicated the best stone for use,
and pointed out the fact that it is not found in all places,
though the mortar may be had everywhere in abundance;
she has, finally, given the plan of the house; but not one
mason or carpenter, through whose assistance alone the
house can be erected, has raised a hand to help her.
Experience, they say, has been for centuries their guide,
and must continue to be so for the future. In their eyes
no views are admissible or possible, which contradict their
views based on this experience. What has been regarded |
from time immemorial as true, must be true. The new
plan is opposed to theirs, which is the best; neither the
draining of the swampy ground, nor the driving of the
piles, nor even the stones which are to be found every-
where, are of any consequence; only the mortar is wanting,
on which every thing depends.

Agriculture, like every technical pursuit, is based on
experience, that is, on the perception by the senses of facts
and phenomena; and it has been enabled by experimental
art to reach a certain stage of development. Simple
observation shows a certain connection between the condi-
tion of the soil and its fertility. Thus, a certain porosity
and dark colour bespeak frequently a heavy wheat crop.
But as all soils do not possess porosity and blackness,
experimental art seeks out the means of communicating

THEORETICAL AND PRACTICAL AGRICULTURE. 3

these properties. It endeavours to produce, for a given
object, a passing or a permanent connection between two
facts; it seeks to win from the soil a high return by this or
that plant, manure, or other means.

Every object attainable by experimental art must be
pursued with certain ideas, but it is immaterial whether
those ideas be right or wrong. For if we seek an object
without knowing the proper way to do so, each path taken
by us is, for the time being, the right one. If, then, thou-
sands of persons with the same intention strike out
thousands of different courses, it will generally happen
that something useful is discovered, although not precisely
the object sought. In this way trades have been developed.
It is almost incredible what can be done, and has, in fact,
been accomplished in this way.

The connection between two objects, such as the soil and
manures, is known only through means of a third, viz., the
amount of produce. For the practical man, “the matter-
of-fact man,” there exists no other connecting link.

The exercise of a trade presupposes no intellectual
labour; a knowledge of facts, and of their visible and
manifest connection with each other, being quite sufficient
for the purpose. The baker knows nothing about flour,
leaven, or the influence of fermentation and heat; the soap-
boiler is ignorant of the nature of the alkaline lye, of fat,
and of soap; but both know that by taking certain steps
bread or soap is produced. Jf the articles look well, they are
said to have succeeded. In like manner, a few years ago, the
agriculturist knew nothing about the soil, the atmosphere,
or the action of the plough or of manures; things with
which he was daily occupied.

The efforts of every tradesman are, as a matter of course,
directed to his profits; every improvement in his business
has the increase of his income for its object. Hence the

4 THEORETICAL AND PRACTICAL AGRICULTURE.

baker regards the highest effort of his art to be the produc:
tion of a white and weighty bread from inferior and bad-
coloured flour; and the soap-boiler aims at manufacturing
from bad fatty matters a soap with good external aspect.
- The practical agriculturist, in the same way, endeavours
to reap the richest harvest from the poorest soil with the
least expenditure of labour and manure. In this petty
aim is manifested the paltry principle of the small manu-
facturer.

The progress of every trade by mere empirical experi-
ence, and also that of agriculture, has a limit. Hvery
experimental method comes to an end when the senses are
no longer sufficient for the perception of facts; when no
new circumstance is presented to the senses for perception ;
when, in short, every thing has been tried, and the facts
resulting from such trials have been adopted into the par-
ticular art or trade. Further progress can then only be
looked for, if hidden facts are sought out, the senses are
sharpened for their perception, and the means of investiga~
tion are improved. But such a course is not possible with-
out reflection, without the mind also taking its share in the
operation.

It is long since agriculture has reached this point of its
progress. As, however, in following out their own practical
mode, agriculturists had never troubled themselves about
the way or the means of discovering hidden facts; it was
evident that without the aid of Chemistry,—the science
which communicates this knowledge,—they could never
attain their end. Chemistry most readily responded to the
call. In the very outset the practical agriculturist was
informed by the chemist that his conception of the words,
air, soul, manure, was indefinite and ambiguous; that they
had a fixed and definite meaning, and that it was only in
this strictly defined form that they could be employed in

THEORETICAL AND PRACTICAL AGRICULTURE. 5

processes of reasoning. Chemistry thus elevated mere
practical notions to the rank of scientrfic conceptions.

The newly acquired conception of manure was accepted
with enthusiasm by agriculturists, and. they set themselves
with zeal to work it. It was known that manure was the
most important element in increasing a crop. It had been
shown that the word ‘‘ manure” was a collective term; that
it consisted of parts, and that its activity depended on its
constituents. The practical agriculturist now began to
operate with the parts as he had done with the whole
manure. But asa part can never replace a whole, so the
results, by this mode of proceeding, did not answer his
expectations. No progress was made. Hnthusiasm began
to cool, and reaction commenced.

“Tt is utterly absurd,” says Mr. Pusey (late President of
the Agricultural Society of England), ‘to put any value on
the doubtful precepts of Chemistry. It has done nothing
for agriculture, with the exception of giving a receipt for
increasing the efficacy of bones by the action of sulphuric
acid, and of proposing to employ flax-water instead of
liquid manure. We must keep to practice, for it alone is
worthy of confidence.” Every practical man in England,
Germany, and France, quite agreed in this opinion. Che-
mistry had done them no good; it had not increased their
crops, nor augmented their incomes.

As if freed from a frightful night-mare, blind empirical
practice again raised her head, and made new and extra-
ordinary efforts to refute the conclusions drawn from scien-
tific principles. The continued efforts of ten years have,
however, shown that practice has only been moving in a
circle, like a horse in a mill. More horses have been
yoked; but as the beam was not lengthened, the circle
has remained the same, only somewhat more trodden than
formerly.

6 THEORETICAL AND PRACTICAL AGRICULTURE.

A new movement now occurred in agriculture. Science
pointed out that the very facts destined to refute her doc-
trines, exhibited the fullest proof of their soundness. Agri-
culturists had themselves to blame for their want of success,
by not taking the right path and by mistaking the nature
and essence of science. It is not at all the province of
science to seek out the means of increasing’ produce or
augmenting incomes. She inquires not after what is profit-
able; this belongs to experimental art, with which she has
been confounded. The business of science is to seek for
causes, and like a light, to illuminate the surrounding dark-
ness. Science confers power, not money; and power is the
source of riches and of poverty,—of riches when it produces,
and of poverty when it destroys ; it is expended by use, and
renewed by supply.

If agriculture is to arrive at results which are to be
lasting, she must decide upon entering on that path which
science has recognised to be the only trustworthy one to
lead to a knowledge of hidden objects and their relations.
This could be done without renouncing one of the facts
acquired by experience. There is no lack of these, but
agriculturists are at fault in their mode of comprehending
them. They must, in the first place, desist from drawing
hasty conclusions for special purposes from these facts, and
only occupy themselves with investigating the proximate
conditions of all the facts connected with the life and
development of plants, the production of which is their
object. From the favourable action of the constituent of a
manure in one case, they must not at once infer its equally
favourable action in another, in order to derive immediate
profit from it; but they ought, in the first place, to inquire
into the reason of its good effects in the special case.

Such investigations are in an agricultural point of view
greatly facilitated by all the conditions of the incidents, or

THEORETICAL AND PRACTICAL AGRICULTURE, 7

effects, or their proximate causes, being clearly perceptible
by the senses, and palpably manifest if we know the proper
way to proceed.

The favourable action of a manure A is always dependent
on certain physical conditions of the soil, and on the pre-
sence of a second substance B, of a third C, of a fourth D,
and soon. After investigating these different points, our
conclusion must then be submitted to proof, which must
show whether all the conditions have been considered
together, and none overlooked. We must endeavour to
produce the same effect in another soil, by the combination
of all the conditions found. Should the result correspond
with our expectations, and be equally favourable as in
the first instance, we have made an extraordinary step in
advance; for from this special case we can now in all similar
cases predict the like or unlike effect of the manure A.
The effects will be like, in every instance in which we
kuow that we have present the same conditions united in
the same manner; and unlike, when one of these is known
to be wanting.

The presence and united action of all the conditions of
the effect observed, is designated by the term, a special law ;
because it refers to a special case, to a certain plant for
instance. If this law holds good for superphosphate of
lime and “turnips,” it does not follow that it is equally true
for ‘‘ wheat.” Buta similar special law can be established
for each manure, each plant; and from these again general
laws can be deduced, which express the conditions of the
growth and development of all varieties of cereals, all species
of turnip and tuberous plants, &e. These connected general
laws now receive the name of theory.

It must be evident, even to the most limited under-
standing, that there is nothing hypothetical in this pro-
ceeding. It differs from blind experimental art, only in

8 THEORETICAL AND PRACTICAL AGRICULTURE.

being the result of thought and reflection. As the train of
thoughts, on which the experiments are based, is carried
out in a precise and fixed direction, this mode of proceeding
has received the name of the znductive method.

The world has been metamorphosed by the introduction
of this method, which was unknown to antiquity. It is
to this method that the present day is indebted for its
peculiar characters. The Greeks and Romans possessed
metaphysics and the fine arts as we do; but the natural
sciences, the offsprings of the inductive method, were
unknown to them. 'T'o this method we owe the millions
of willing’ and industrious slaves, whose labour costs no
tears or groans. It has bestowed on Germany alone what
is equivalent to from 700,000 to 800,000 horses, which,
with untiring energy, and with the speed of the wind,
bring from the most distant lands their various products to
satisfy the wants of man; and they need no hay, no corn
to feed them. The fruitful land necessary to produce the
food for this number of horses of flesh and blood, remains
for the use of five to six millions of men, who can be main-
tained on its surface.

Conclusions deduced from this method of investigation,
are evidently but the intellectual expressions for experi-
ments and facts. The practical man who adopts this
method of solving all useful questions, need entertain no
dread of acquiring the reputation of a theorist, which he
considers to be of a rather doubtful nature. He may rest
assured that by no other means can he solve a single
problem. He must first seek after the “why,” and the
“ wherefore ” will follow as a matter of course.

It would be unjust to conceal the fact that, for more than
half a century, agriculturists have directed all their efforts
to gain an insight into the processes of husbandry. They
have endeavoured to connect all its phenomena together by

THEORETICAL AND PRACTICAL AGRICULTURE. 9

some intelligible bond, and to ascertain the relation and
dependence of its scattered facts.

Agriculture could not remain unaffected by the extra-
ordinary progress of other trades depending on the action
of natural forces. The natural sciences were even recog-
nised to be the source of this progress. Wise and intelli-
gent princes erected schools and institutions, for the express
purpose of teaching the doctrines and truths of the natural
sciences in connection with the practice of agriculture, of
investigating the best modes of cultivation, and of widely
spreading the knowiedge of them.

Agriculturists felt the necessity of accounting for their
acts; and the knowledge that they were doing the right thing
in the right way, appeared to all indispensable to progress,

If we open a recent hand-book of practical agriculture,
we at once see the zeal with which this task has been per-
formed. ‘The effect of soils, manures, irrigation, drainage,
and the action of each fertilising agent on individual classes
of plants, are all brought into harmony and explained in
the most beautiful manner. Everything seems in such
works to have been investigated and ascertained; no pro-
cess is involved in obscurity; and a certain feeling of pride
seems to fill the breast of the teachers who have done so
much to elevate agriculture to the rank of a science.

But this ts all sham, without a single law or a single truth.*
“Tf there is a class of mind in the world which has a native
antipathy to improvement, there is another and much more
really mischievous, which seems ever destined to caricature
it. . . . These are the blundering enthusiasts who dog
the path of progressive truth, like distorting shadows,
throwing her calm profile against walls, trees, and passing
- objects, in every variety of burlesque and ridiculous out-

* The Chronicle of a Clay Farm, by Talpa.— Agricultural Gazette.
1*

10 THEORETICAL AND PRACTICAL AGRICULTURE

line; . . . exaggerating every account like street news-
vendors; dressed in the livery of science like a mon<ey in
regimentals, and understanding and appreciatig the lan-
guage they talk at second-hand, as much as the organ-
grinder does the opera tune that his winch works thread-
bare.

‘“ Agriculture has had enough of this and something to
spare. Counterfeits of every sort and shape have crowded
at the heels of every improvement, every invention, every
good suggestion, every new manure; till art and science
are well nigh ashamed of their own names, and are fain to
wear smock-frocks for an incognito. The plague that has
reached its height in the present decade, was beginning
its infective process in the last of our nineteenth century.”

Agriculturists knew not that the explanation of the most
trifling incident or process, or the discovery of the almost
self-evident cause of an effect, costs much pains and cir-
cumspection; that in chemistry, for example, the simplest
explanation of a single individual fact has been attained,
only by persevering labour. They thought that to will,
was to obtain possession; and they hence gave themselves
up to the direction of those caricaturists of science who
promised them success without any efforts on their part.
They were well pleased with their sham scientific mode of
proceeding, with which they were at home, and which cost
them but little trouble. The language alone was new, but
technical terms were soon learned. Each individual con-
sidered himself as fully qualified to institute chemico-
agricultural experiments ; and these were undertaken even
by men who knew no more about chemistry than the
student who considers that the distillation of a fluid is to
be attained by simply placing it in the sun, or the other
who asked the chemical assistant in a laboratory for a grater
to pulverise a mineral.

THEORETICAL AND PRACTICAL AGRICULTURE. 11

Such men arrived at explanations in the simplest manner
possible. If between two facts there existed a certain and
unmistakeable connection,—such as for example, between
wrrigation and the increase of grass on a meadow,—these
pseudo-scientific experimenters drew on their imaginations
for the explanation of this connection.

The causes of the effect produced were unknown. There
was, however, an effect visible, and it must have a cause.
The expounder began first by mystifying with a chemical
hocus-pocus of analysis, the good-natured agriculturist
thirsting after knowledge; and when he had sufficiently con-
fused the sound common sense of the latter by unmeaning
numbers and calculations, he quietly palmed off on him his
explanation which he had ready prepared.

The connection between two facts was not, however,
always so palpable, as between irrigation and production
of grass; but our agricultural expounders were never at a
loss. If they wished to show, for example, the connection
existing between the exhaustion of the soil and the cultiva-
tion of cereals, they required only to call to their aid certain
speculative views derived from experience. For such
occasions they had always ready chiefly two famous theo-
ries, viz., the ‘bone earth” and the “nitrogen” theories.
The latter has attained great celebrity in England, and in
Germany. too, it has found ardent supporters.

There can be only one straight line between two points;
but billions of curved lines may connect them. Thousands
of hypotheses may, in like manner, be propounded to
explain the connection of two facts; but there can be only
one right theory. Every one will therefore understand
that agriculture, by following the method described above,
could never arrive at the right way of explaining her
various facts. The popularity of this mode of proceeding
arose from the circumstance that knowledge was not

12 THEORETICAL AND PRACTICAL AGRICULTURE.

required to practise it. Every agriculturist, in his own
estimation, possessed the necessary qualifications for the
purpose. He knew the facts, and his own experience was
quite sufficient to connect them. But as the individual
experience of each necessarily varied in many respects, it
followed that each had his own peculiar theory for his pro-
ceedings and his mode of viewing things.

In reality these theories were but little regarded. The
practical man kept to what had been tried, and acted upon
it. If his neighbour made a successful trial, he imitated
his example. This was his mode of making progress; he
knew no other.

The practical agricultural system of instruction was a
mere collection of different receipts suitable to known
cases; it was an olla podrida of facts, with theory as a kind
of sauce to it.

The agriculturist commencing his career became a prac.
tical man, and acquired reputation and honour somewhat
like the so-called “green” Doctor of Offenbach on the
Maine, who will perhaps still be recollected by the older
inhabitants of this town. He was a Jewish physician of
renown who was called in to all dangerous cases of illness
in Frankfort, Hanau, and the neighbourhood; and his
practice was not without success. Nature had given him
a quick eye and fine powers of observation. His know-
ledge was obtained in an hospital in which he acted as sick
attendant. He used to accompany the physician through
the sick wards, looked at the tongues and urine of the
patients after him, felt their pulse, and superintended the
orders about their diet. He copied the prescriptions regu-
larly; marked them with a red cross when the patient
recovered, and with a black one when he died. His sheets
grew by degrees to the size of a book, and when nothing
new presented itself to be added to it, he began in the first

THEORETICAL AND PRACTICAL AGRICULTURE, Pe

instance to practise on a small scale, and then started on
the full career of physician. He was skilled in diagnosis,
and had his prescriptions for the various cases. Those
with the red crosses came first; and, if unsuccessful, then
followed the black. In this way he acquired his own expe-
rience. He was very orthodox, and on the Sabbath day
would write no prescription, but would then dictate them
in the apothecary’s shop to the assistant. He commenced
with ‘ frrrr” (this meant Recipe); ‘ Zariemet, two grains”
(2. e. Tartari emetici grana duo); Syralth (7 e. syrupus
althex). He could not read his own prescriptions, but his
fame as a practical physician was so established, that the
regularly educated physicians in Offenbach could not suc-
ceed in putting an end to his career, on the ground of his
never having received a medical education.

Agricultural practice is acquired in the present day
exactly in the same way as the medical skill of the Offen-
bach doctor. The young agriculturists become sick atten-
dants in an agricultural hospital; they copy the prescrip-
tions, and when they depart for the purpose of beginning
practice, the kindly directors send them on their way, with
the substance of two years’ earnest devotion to all the aux-
iliary sciences summed up in an axiom, “Dung, Guano,
and Bone-earth, you must not forget, gentlemen, are, and
remain the soul of agriculture.”* They knew this very
well. They had been taught that no trust was to be put
in chemistry or physics; that food and drink keep body
and soul together; and that beer, bread, and meat, are
the soul of the handicraftsman.

Under such circumstanees, it cannot excite astonishment,
that for more than sixteen years true science found no soil
in agriculture for its development. The most exact induc-

* See G. Walz. Beleuchtung. p. 128.

14 THEORETICAL AND PRACTICAL AGRICULTURE.

tive conclusions were only regarded as hypotheses. It has
ever been the case that when error sat enthroned, truth,
like a felon, was kept bound in chains. What arrogance
in science to regard practical men like us as blind men, and
to attempt to make us see. How can men who know not
whether potatoes should be planted in March or April,
presume to teach us the properties which land suitable for
potatoes ought to possess,—or what is the nature of fallow?
Such scientific explanations are not based on experience;
we can ourselves give much better. Whoever should
attempt to depose farmyard manure from its exalted posi-
tion deserves to be burnt alive!

Agriculturists had not yet acquired the faculty of dis-
tinguishing between mere opinions and correct facts.
Kvery fact was acceptable; every opinion was received
by them. Jf science doubted the truth of one of their ex-
planations, they imagined that she was disputing their facts.
If she asserted that a great progress would be made by
substituting for stable manure its active constituents, they
believed that in doing so she denied the efficacy of the
former.

About misunderstandings of this kind disputes then arose.
The practical man did not yet understand the deductions
of science. His dispute was with the bugbear of his own
false conceptions, not with science. He did not know that
science also has a moral of her own, the foundation of
which lies in the precepts of the school and their practice
in education.

As a means of mental training, the study of the natural
sciences was quite unknown to the practical man; and
hence the difficulty which existed between him and the
scientific man of mutually understanding each other. Had
the former turned his attention even in a slight degree to
these sciences, he would of himself have acquired all the

THEORETICAL AND PRACTICAL AGRICULTURE. 15

information which it now costs so much trouble to make
intelligible to him.

In physics and chemistry, disputes of this nature occur
no longer, though the time is not long past since both
were at that point of development which agriculture has
still to pass.

A glance at a chemical or physical journal must fill the
mind of an agriculturist with astonishment at the mass of
problems and their solutions which it contains, and at the
immense labour which has been readily and without reward
bestowed upon the whole. Each day brings its own pro-
gress without strife, for each cultivator of these sciences
knows what constitutes a fact, conclusion, rule, law, opinion,
and explanation. There are specific tests for all these
which every one uses, before he puts each to the test of
its own peculiar touchstone, before he circulates the fruits
of his labour. ach assiduously seeks to bring to light
hidden facts, which are immediately submitted to proof by
others, and receive their proper place when they are found
to be genuine. One individual possesses the talent for seiz-
ing the points of resemblance between two facts; another
has a keen eye for their differences; in this way they render
mutual assistance in the proper elucidation of phenomena.
Special pleadings on the part of any one for his own pecu-
liar views, without striking facts to support them, or the
attempt to palm off on others any unproved facts, is in-
stantly rebutted by the moral of science. The earnest desire
of a mutual understanding is ever paramount.

The most intelligent representatives of agriculture have
hitherto erred in not discussing their questions in the way
which would have led to the attainment of their object.
Great agricultural associations, as well as individuals, have
proposed questions, and recommended their solution as
absolutely necessary for future progress. The majority of

16 THEORETICAL AND PRACTICAL AGRICULTURE.

agticulturists have a monomania for propounding such
questions, and deceive themselves with the belief that their
solution will be attended with sound practical information.
Not one of them knows exactly what is wanted, but each is
anxious to contribute his suggestions. Such questions pro-
pounded by persons who know nothing of the subject are
answered by others who understand it as little. Not one,
however, really cares about the answer, for they all clearly
see that they would not know what to do with it.

There is a good method of satisfying ourselves of this
fact. We have only in our minds to answer these ques-
tions with “yes” or ‘‘no,” or with any negative or positive —
number we choose, when the answer involves numbers,
and we shall at once see that they are thoroughly unprac-
tical, or belong to the same stamp as the prize question of a
well-known Academy—‘ The decomposition of Nitrogen,”
a problem which now seems to us more difficult than the
solution of charcoal for the purpose of making diamond.
The solvers of such questions (and here I speak only of
agriculturo-chemical), are hence always persons who do not
possess the necessary knowledge to make the most trifling
discovery. About fifteen years ago Hlubeck propounded
a series of questions, on the solution of which the very
existence of agriculture appeared to him to depend. Since
then, neither he nor any other person has troubled himself
about the matter; and the present state of the development
of agriculture is a proof, that none of his questions stood
in any relation to it, or exercised any influence upon its
progress.

These questions are always tokens of progress. They
prove that agriculture has really passed from the state of
blind empiricism into the first stage of its scientific develop-
ment, viz. into that of its infancy, in which curiosity mani-
fests itself by a multitude of questions. In this point of

THEORETICAL AND PRACTICAL AGRICULTURE, 17

view we may, after all, rejoice that such questions are
really put.

Chemistry and physics have likewise passed through the
same stages. Academies and learned societies have in their
time proposed an incredible number of absurd prize questions
and impossible problems, without having thereby exercised
any important influence on the furtherance of science.
Those who are not well acquainted with the position in
which these problems stand to science, would be easily
misled into the belief that they have given origin to many
truly substantial works. . This is, however, an error, for the
problems were proposed by those who knew that their solu-
tion was already in progress; or the questions came acciden-
tally in the way of men who had been long previously
occupied with them.

Prizes, sometimes of a very high value, were attached by
the Academies to the solution of their questions; but as our
excellent agriculturists regard the answering of their ques-
tions as an honour, they may, on that account, calculate the
more certainly that nobody will take any notice of them.

At their great meetings the practical agriculturist com-
municates his experience, and expresses his views. The
final result is always a mutual agreement between those who
differ in opinion; and each goes home with the proud con-
sciousness of having convinced the others that he is a man
of progress, and has taken his part in it. Principles are
left out of the question; effective manures and experiments
alone are wanted. . Poor soils cannot be fertilised by funda-
mental truths.

A few years ago a writer expressed in such a meeting a
modest doubt as to the duration of the nitrogen theory so
strongly maintained in England, but they unanimously
passed to the order of the day, as experience had long since
decided the question of its value.

18 THEORETICAL AND PRACTICAL AGRICULTURE.

One of the worst points in the character of practical men,
is their sensibility to opposition. The total want of founda-
tion for their erroneous views is the reason why they regard
them with so much affection and tenderness. It makes them
blind to their own interest, and deaf to all instruction.
They look on every one as an enemy who does not flatter
their prejudices, who openly tells them that there yet remains
much to be learned, and that the consciousness and confes-
sion of our ignorance, and the knowledge of our faults, are
the first steps towards improvement. I, who in my heart
believe myself to be their most candid and sincere friend,
must, therefore, at once make up my mind to bear with
resignation the whole weight of their contempt, with which
pride in their own experience fills them, if I attempt to
prove the assertion, that the prevailing system of agriculture
for half a century has been one of spohation; and that, if
persisted in, the inevitable result will be, at no distant date,
the ruin of their fields, and the impoverishment of their
children and posterity.

LETTER I.

Present pront 1s the leading principle of the prevailing system of Husbandry
—tThis system is one of danger to Agriculture—-General view of the
Nutrition of Plants—Atmospheric and Mineral Food—The absolute neces-
sity to Plants of all the Constituents of their Mineral Food—Present
views of the Nutrition of Plants erroneous—Rain water does not dissolve
out the Mineral matters in the Soil—Remarkable absorbent power of Soils
for the soluble Mineral Food of Plants, and particularly for Potash, Ammo-
nia, and Phosphoric Acid—This power is limited, and varies with the Soil
—Organic matter in the Soil materially modifies this power.

BEFORE proceeding to prove that our present system of
agriculture is one of spoliation, 1 must from the outset
remark, that I do not by this mean, that each agriculturist
acts contrary to the rules of logic and common sense in
tilling his ground in the manner most advantageous to him-
self. On the contrary, I feel satisfied that, so far as the
attainment of this point is concerned, our practical agricul-
turist is very reasonable and logical. He knows, in general,
the means of rendering barren grounds fertile, and of obtain-
ing the best crops from fertile fields; and he employs these
means with reflection and skill, for they have been known
and proved for ages.

A field from which a large crop of corn has been reaped,
is again enabled to produce the same crop by mechanical
preparation and by manure. Any peasant, who cannot
read or write, knows that such a result will follow the
employment of these two means.

it is asserted, that the present system of husbandry
yields greater crops, and produces more corn and meat,

20 THEORETICAL AND PRACTICAL AGRICULTURE.

with more profit, on the same area than formerly. I will
not, at present, contest this point, and therefore it is not
now my object to attack this system, but rather to discuss
the question, whether or not it is a rational one. If the
large crops are a consequence of a mode of management
by which the ground must gradually lose the conditions of
its fertility, by which it must be impoverished and
exhausted, then such a system is not rational, though
it enrich the individual who obtains these high returns.

I am aware that the majority of agriculturists are fully
satisfied that their mode of husbandry will insure a con-
tinuance of fertility to their fields. If I can succeed in
awaking a doubt in this belief, I shall have gained an
important point. The simple perception of their error will
suffice to lead to its correction.

I hold it, indeed, to be no longer possible to bestow again
upon the soil all those conditions of fertility which have
been withdrawn by the existing mode of husbandry; but,
by a judicious system of management, so much may be
accomplished with the still existing means, as to put in the
shade all that has hitherto been done.

To comprehend clearly the existing system of agricul-
ture, we must recall to mind the most general conditions of
the life of plants. |

Plants contain combustible and incombustible constitu-
ents. ‘The latter, which compose the ash left by all parts
of plants on combustion, consist in the case of our culti-
vated plants, essentially of phosphoric acid, potash, silicic
and sulphuric acids, lime, magnesia, tron, chloride of
sodium.

It is now regarded as an undisputed fact, that the consti-
tuents of the ash are elements of food, and hence are
indispensable to the structure of the different parts of the
plant. Its combustible portion is derived from carbonic

THEORETICAL AND PRACTICAL AGRICULTURE. yA

acid, water, and ammonia, which as elements of food are
equally indispensable.

By the vital process plants are formed from these
materials, when the atmosphere and soil supply them at —
the same time in suitable quantity, and in the proper pro-
portions. ‘T’he atmospheric elements do not nourish with-
out the simultaneous action of the elements of the soil; and
the latter are equally valueless without the former. The
presence of both is always required for the growth of the
plant.

It hence follows, as a matter of course, that no single
element of the food of plants, named above, possesses
superiority over another: they are all of equal value to the
life of the plant. But to the agriculturist, who must pro-
vide a suitable supply of all these substances in his land to
accomplish his particular object, they are, on the other
hand, of unequal value. For should there be a deficiency
of one of them, he can calculate on his crop only by sup-
plying that particular one to the soil. The deficient or
absent element then acquires a superior value, that is, in
relation to the other matters (for example, lime in a lime
soil), which the soil contains in greater quantity.

All elements of food of plants belong to the mineral
kingdom. The gaseous elements are taken up by the
leaves; the fixed by the roots. The first are frequently
constituents of the soil, and, as such, reach the interior of
plants by the roots as well as by the leaves. From their
nature, these gaseous elements are movable; the incom-
bustible ingredients are zmmovable, and cannot of them-
selves leave the spot in which they are found.

An element of food is ineffective if there be absent a
single one of the other elements of food which are condi-
tions of its activity.

Corn plants, and those used for fodder, require for their

22 THEORETICAL AND PRACTICAL AGRICULTURE.

development the same constituents, but in very unequal
proportions. The successful growth of a green crop on a
field, proves that it has found in the air and in the soil the
atmospheric and mineral constituents of its food in the pro-
portions suitable for its nourishment. The failure of a
corn crop on the same field, indicates that in the soil there
is something wanting which is necessary for its growth.
Hence we must in every case of the failure of a cultivated
crop, look to the ground for the cause, and not to any
want of atmospheric food; for the same source of atmo-
spheric food was available to the corn plant as to the green
crop.

But how does the soil act, and in what manner do its con-
stituents take part in vegetation? ‘This question we shall
now consider a little more in detail.

The process of nutrition consists in the appropriation of
food. A plant grows by increasing in bulk; and its bulk
increases by the constituents of its food becoming constituents
of its frame. From carbonic acid, for example, sugar is
formed; silicic acid becomes a component part of the stem ;
potash of the sap; phosphoric acid, potash, lime, magnesia
of the seed.

In considering the effect of an element of food, we have
to distinguish between the rapidity and the duration of its
action.

In general the result depends on the sum of the active
elements available in the soil, in relation to the amount which
the plant may altogether absorb, and does absorb, during
the period of vegetation. A deficiency diminishes the crop,
but an excess does not increase it beyond a certain limit.
The excess comes into play in the succeeding period of
vegetation. The continuous cultivation of crops is regulated
by this excess which remains in the ground after each period
of vegetation. If this residue is ten times greater than is

THEORETICAL AND PRACTICAL AGRICULTURE. 23

necessary for a full crop, then it will suffice for ten full crops
during a period of ten years.

_ The rapidity with which a substance, such as a piece of
sugar, is dissolved by a fluid, is in proportion to its state of
division. By pulverization its surface is increased, and con-
sequently the number of points augmented, which, in a
given time, are brought in contact with the dissolving fluid.
In all chemical processes of this kind, the action proceeds
from the surface. An element of food in a soil acts by its
surface, the portion beneath the surface is inactive, because
it cannot be dissolved. Its effect, within a given time,
increases with the quantity taken up by the plant during
that time, Fifty pounds of bones may in one year produce,
according to their state of division, the same effect as one,
two, or three hundred pounds coarsely ground. In the
latter state it is by no means inefficient; but to act, that is,
to become soluble, it requires a longer time. The effect
produced by it is smaller, but it continues longer.

To understand correctly the effect of the soil and its con-
stituents on vegetation, we must keep steadily in view the
fact, that the elements of food present in it always possess
within themselves active powers, but they are not always in
a condition to exert this power. ‘They are ready to enter into

circulation, like a maiden to dance, but a partner is necessary. .

The agriculturist requires eight substances in his soil, if

all his plants are to flourish luxuriantly, or his fields to |

produce the largest crops. Many of these, though not all,
are always present in quantity; three require to be added
to most fields. These eight substances are like eight links
of achain round a wheel. If one is weak, the chain is soon
broken, and the missing link is always the most important,
without which the machine cannot be put in motion by the
wheel. The strength of the chain depends on the weakest
of the links.

24 THEORETICAL AND PRACTICAL AGRICULTURE.

We have hitherto believed that plants received their food
from a solution, and that the rapidity of its effect was in
direct proportion to its solubility. We have supposed the
active elements to be carried in solution in rain water and
carbonic acid to their roots, and have regarded them in the
light of sponges, half in the moist ground and half in the air,
continuously absorbing by their roots the water which eva-
porated from their leaves. Whatever was in solution passed
with the water into the roots, and by the process of nutrition
was appropriated by the plant. The soil and the plant were
both passive in the operation.

Vegetable physiology has taught, that an element of food
in the soil, at a distance from the rootlets of plants, is avail-
able as nourishment, provided there is water between the
rootlets and the, food to dissolve the latter. In consequence
of the evaporation from the leaves, the rootlets suck up the
water, which thus, with the substances dissolved in it,
receives 4 movement onwards towards them. We believed
that the water was the carrier of the most remote elements
of the soil to the immediate presence of the plant.

If 4000 lbs. of grain and 10,000 lbs. of straw require 100
Ibs. of potash and 50 Ibs. of phosphoric acid for their deve-
lopment, and if a hectare of ground contain these quantities
in a soluble available form, then there will be sufficient for
this crop. If the same field contain double, or a hundred
times as much, then we should expect two or a hundred
crops. This has been the physiological doctrine.

But all this has been a great mistake. We have inferred
from the effect of water and carbonic acid on rocks, a simi
larity of action on soils; but this conclusion ts false.

There is not to be found in chemistry a more wonderful
phenomenon, one which more confounds all human wisdom,
than is presented by the soil of a garden or field.

By the simplest experiment, any one may satisfy himself,

THEORETICAL AND PRACTICAL AGRICULTURE. 25

that rain water filtered through field or garden soil, does not
dissolve out a trace of potash, silicic acid, ammonia, or phos-
phorice acid. The soil does not give up to the water one
particle of the food of plants which it contains. The
most continuous rain cannot remove from the field, except
mechanically, any of the essential constituents of its fertility.

The soil not only retains firmly all the food of plants
which is actually in it, but its power to preserve all that may
be useful to them, extends much further. If rain or other
water, holding in solution ammonia, potash, phosphoric and
silicic acids, be brought in contact with the soil, these sub-
stances disappear almost immediately from the solution; the ©
soil withdraws them from the water. Only such substances
are completely withdrawn by the soil as are indispensable
articles of food for plants; all others remain wholly or in
part in solution.

If a funnel be filled with soil, and a dilute solution of
silicate of potash be poured upon it, there will not be found
in the filtered water a trace of potash, and only under cer-
tain circumstances silicic acid.

If freshly precipitated phosphate of lime, or phosphate of
magnesia, be dissolved in water saturated with carbonic acid,
and filtered in like manner through soil, there will not be
found a trace of phosphoric acid in the filtered water. A
solution of phosphate of lime in dilute sulphuric acid, or of
phosphate of magnesia and ammonia in carbonic acid water,
comports itself in the same manner. The phosphoric acid
of the phosphate of lime, and the phosphoric acid and
ammonia of the magnesia salt remain in the soil.

Charcoal re-acts in a similar manner with many soluble
salts; it removes colouring matter and salts from solutions.
It is natural to look upon the effect in both cases as pro-
ceeding from the same cause. In the case of charcoal, it is
a chemical attraction, which proceeds from its surface;

2

26 THEORETICAL AND PRACTICAL AGRICULTURE.

but the constituents of the soil take part in its action, and
hence it must in many cases be quite different from that
of charcoal.

Potash and soda are well known to stand to each other
in the closest chemical relation, and even their salts have
many properties in common. Chloride of potassium, for
example, has the same crystalline form as chloride of
sodium; and in taste and solubility they differ but slightly.
An unpractised eye can scarcely distinguish them, but the
soil can do this in the most perfect manner.

If we add any soil in powder to a dilute solution of
chloride of potassium, in a short time there will not be
found any potassium in solution. The same quantity of
earth does not withdraw from a solution of chloride of
sodium, containing an equal amount of chlorine, even the
half of the sodium. Consequently, a complete decomposition
takes place with the potassium, but only in part with the
sodium. Potash is found in all our land plants, but soda
forms only an exceptional constituent of their ashes. From
sulphate and nitrate of soda, the soil withdraws only a part
of the soda, but the whole of the potash from the corres-
ponding potash salts. Experiments, expressly made for this
purpose, have shown that 1 litre = 1000 cubic centimetres
(= 61 cubic inches Eng.) of garden soil, rich in lime, will
take up the potash from 2025 cub. cent. (= 128°6 cub.
inches, or 84 pints) of a solution of silicate of potash, which
contains in every 1000 cub. cent. 2°78 grammes (= 48 grs.)
of silicic acid, and 1:166 grammes (= 18 grs.) of potash.
From these data we can calculate that a field of a hectare
(= 24 acres) in extent, and having a depth of 4 of a metre
— 10 inches nearly) of soil, of the same kind as that used
in the experiments, would withdraw from a similar solution
more than 100,000 Ibs. of potash, and retain them for the
use of plants. A similar experiment, made with a solu-

THEORETICAL AND PRACTICAL AGRICULTURE. 27

tion of phosphate of magnesia and ammonia in carbonic acid
water, showed that a 21 acre field would withdraw 5000
Ibs. of this salt from such a solution. A loam (poor in
lime) produces the same effect.

These facts give us some conception of the powerful
action of soils, and of the strength of their attraction for
three of the chief elements of the food of our cultivated
plants, which, in consequence of their solubility in pure and
carbonic acid water, could not be retained in the soil, did
the latter not possess this power of attraction.*

From stale urine, liquid manure diluted with much water,
or from a solution of guano, soil, when used in sufficient
quantity, removes the whole of the ammonia, potash, and
phosphoric acid which they contain. Not a trace of these
substances can be found in the water which flows from the
soil. (Thompson, Huxtable, Way.)t+

* These experiments are so simple and so easily performed, that they may
be exhibited at lectures. In filtering, care must be taken that the fluid does
not form canals, which would prevent the complete contact of the solutions
with the soil. Very dilute solutions of silicate of potash, chloride of potas-
sium, &c., must therefore be used, in the proportion, for example, of one part
of substance to 500 of water. Saturated solutions of the other substances, such
as phosphate of lime in carbonic acid, may be employed. Generally, in the
first portions of filtrate from the phosphate of lime, not a trace of phosphoric
acid can be detected by molybdate of ammonia. A solution of silicate of
potash, which re-acts distinctly alkaline with turmeric paper, instantly loses
this re-action by simple mixture with soil. This power of absorption in soils
for ammonia was observed by Thompson, and for phosphoric acid and some
potash salts by Way, so long ago as 1850; but up to that time neither
vegetable physiologists, nor scientific agriculturists, had taken notice of the
remarkable discoveries of these English chemists, so pregnant with important
results to physiology and agriculture.

+ I cannot here omit a circumstance communicated to me a few years ago
hy Dr. Marquart, of Bonn, and which illustrates, in a remarkable enough
manner, the power of absorption of clays for ammonia.

A manufacturer on the Rhine conceived the idea of extracting, by means
of ammonia, the oxide of copper, which was found as malachite and azure-

28 THEORETICAL AND PRACTICAL AGRICULTURE.

The power possessed by soils to withdraw ammonia, pot-
ash, phosphoric and silicic acid, from solution, is limited.
Each soil is endowed with its own peculiar capacity in this
respect. When brought in contact with these different
solutions, the soil becomes saturated with the dissolved
matter, and the excess of soluble substance then remains
in solution, and can be detected by the ordinary re-agents.
A sandy soil absorbs less than the same volume of a marly
soil. And the latter less than a clay soil. The variations
in the quantity of matter absorbed are as great as the differ-
ences existing among the soils. We know that no two are
alike; and it is not improbable that certain peculiarities in
cultivation stand in a certain relation to the unequal power
of the different soils for absorbing one of the above sub-
stances. It is not impossible, that, by a closer study of
this relation, we may arrive at quite new and unexpected

spar dispersed through shale. The experiment had succeeded with him on a
small scale. At a considerable expense he constructed a large extraction
apparatus, consisting of two boilers connected by a very wide tube. The
fluid ammonia was placed in one boiler; the tube was filled with the shale;
and the second boiler served as condenser. By this arrangement it was
intended that the ammonia and vapour of water should be condensed in the
tube, and, after dissolving the oxide of copper, pass over into the second
boiler. The tube was then to be filled with fresh shale, the ammonia to be
driven by heat from the solution in the second boiler, and made again to
extract the copper from the fresh shale. As the whole apparatus was her-
metically closed, it was hoped that the same quantity of ammonia would serve
without loss to extract large quantities of shale. The boilers were employed
alternately as condensers. ‘The first trial was so far successful, that a solution
of oxide of copper really collected in one of the boilers. But on passing the
ammonia through a second portion of shale, it disappeared in a manner most
incomprehensible to the manufacturer. The process had in consequence to
be abandoned. The disappearance of the ammonia in this operation was
undoubtedly due to the absorbent power of the clay of the shale. This fact
may be taken as a proof of the powerful attraction existing between these
two substances, which apparently could not be overcome even by the influ-
ence of a high temperature.

THEORETICAL AND PRACTICAL AGRICULTURE. 29

means of judging of the agricultural value or fertility of
our fields,

The action of a soil, rich in organic matter, on the solu-
tions above mentioned, is worthy of remark. A clay or
lime soil, poor in organic matter, withdraws all the potash
and silicic acid from a solution of silicate of potash ;
whereas one rich in so-called humus extracts the potash, but
leaves the silicic acid in solution. This comportment invo-
luntarily recalls the action of decaying vegetable remains in
the soil on the growth of plants, which, like reeds and
horse-tails, require a large quantity of silicic acid. These
plants abound in so-called sour moor and meadow lands ;
but disappear from them on the application of lime, and
give place to others better fitted for fodder.

Experiment shows, that the same garden and forest soil,
rich in humus, which withdraws no silicic acid from a solu-
tion of silicate of potash, immediately acquires the power
to do so, if it be mixed with a little slaked lime before the
silicate is added to it. Both constituents, potash and silicic
acid, are then retained by the soil.

LETTER I.

Our cultivated plants do not receive their food from Solution—Roots of plants
derive their Nourishment only from those portions of Soil absolutely in
contact with them—This view supported by the composition of River,
Well, and Drainage water—The Roots of plants must themselves exert
some peculiar action in Nutrition—The Life of land-plants endangered by
food when in Solution—In Water-plants the laws for the absorption of
Food must differ from those of Land-plants—The Ash of duck-weed shows
that plants have a Power of selecting their Food—Reason why mud from
stagnant pools is a good Manure—Remarkable power for absorbing Mois-
ture possessed by Soils—By absorption and evaporation of Moisture, the
Soil is warmed or cooled—Great importance of this fact to Vegetation—
The two Sources from which Moisture is absorbed by the Soil—Natural
Law deduced from the above facts.

THERE can be no doubt, from the action just described
of soil on potash, ammonia, and phosphoric acid, that the
majority of our cultivated plants cannot receive out of a
solution from the soil their essential mineral constituents.
For if, after filtering a solution of potash or ammonia
through a layer of soil of no greater thickness than usually
occurs in a field, these substances are so completely with-
drawn from the powerful acids with which they are com-
bined, as well as from the watery solution, that chemical
analysis can scarcely detect a trace of them in the filtrate,
it is not probable that rain-water alone, or even by the aid
of a small per-centage of carbonic acid, should possess the
power of extracting them from the soil, and forming a solu-
tion which should not again be decomposed by passing
through the ground. The same fact holds good for phos-
phoric acid and its salts. Carbonic acid water will every-

THEORETICAL AND PRACTICAL AGRICULTURE. 31

where dissolve phosphate of lime when it comes in contact
with it; and the consequence of this solution can only be
its distribution through the soil. But such a solution
could not pass from the spot in which it was formed with-
out being deprived of all the dissolved salt by such por-
tions of the soil as are not already saturated with it.

These substances are present in the soil in a condition
somewhat like colouring matter in charcoal, or iodine in
starch, fit for absorption by the rootlets of plants, but
not by themselves soluble in rain water, or removable by
this solvent until the soil is saturated with them.

It is more than probable that it is assigned to the
majority of our cultivated plants to receive their nourish-
ment directly from those portions of soil which are in
immediate contact with their rootlets, and that they die
when their food is presented to them in solution. The
action of concentrated manures, which are said by agricul-
turists to burn the young plants, appears to stand in some
connection with this supposition.

The composition of our common river, well, and drain-
age water from land, may serve to support these conclusions.

A number of excellent analyses of river and well
waters has been published by Graham, Miller, and Hof-
mann (Chem. Soc. Qu. T. iv. 375), from which it appears
that 100,000 gallons, or 500 tons of Thames water, taken
from five different places, contain :— ‘

Thames Dittun, Kew. Barnes, Redhouse, Battersea. Lambeth.
Pounds of Potash, 13 4°71 3°65 10 7:3

The following well waters contain, in 100,000 gallons :—

Witley. Critchmere. Vellwool. Hindhead. Barford. Cosford House.
Pounds of Potash, 2°71 2°5 3 0:7 18 6

Thomas Way found in drainage water—that is, in rain-
water (which had naturally percolated through the soil),

382 THEORETICAL AND PRACTICAL AGRICULTURE.

taken from seven different fields, the following constituents
(Journal of the Roy. Ag. Soc., vol. xvii. 133) :

Grains in 1 Gallon = 70,000 grains of water.

ee eee ee | |

Ode. a clele a deg wi 1:00 | 2°17 | 2°26 | 0°87
Tame, G00 6 c's enawet 28} Lis | 60a | 2°36
Magnesia......... 0°68 | 2°32 | 2°48 | 0°41
Tron and Alumina..}| 040 | 0:05 | 010 | ——
Sili¢a. oc xneeectes| O90 | O45-7 O55 T 120
Ghloriie. yi ..255. O-'TO | 22:40) TET eB L
Sulphuric acid..... 1:65 | 5°15 |] 440 | 1-71
Phosphoric acid....| Trace | 0°12 | Trace | Trace

Ammonia........ -| 0°018) 0018) 0°018) 0012

Very similar results were obtained by Dr. Krocker from
his analysis of drainage water from Proskau (Lieb. and
Kopp’s Jahr., f. 1853, p. 742):—

Drainage Water (in 10,000 parts).

a b Cc d e f*

Organic matter..........- 0°25 | 0°24 | 0°16 | 0-06 | 0°63 |- 0°56
Carbonate of lime......... 0°84 | 0°84 | 1:27 079 | O71 | O84
Sulphate of lime. ......... 2°08 | 210 |) 1:14; 017 | O77 | O72
Nitrate of fime.’...<..0 cece 002 | 002 | 0°01 | 002 | 0°02 | 0-82
Carbonate of magnesia..... 0-70 | 0°69 | 0°47 | O27 | O27 | O-16
Carbonate of iron.......... 0:04 | 0°04 | 0°04 | 0°02 | 0°02 | 0-01
Pete So came Sete ss} MO2 0°02 0 02 0°02 0:04 0°06
0: GEM yey 8 22 0°11 0°15 0:13 0°10 0°05 0°04
Chloride of sodium........ 0:08 0:08 0:07 0 03 0-01 0°01
Ee cS 5 ae as'clae eae bee oe 0°07 | O07 | 006 | 0°05 | 0:06 | 0°05
Total solid matter..... 4-21 | 4-25 | 3:37 | 1:53 | 258 | 2-47 |

* q Drainage water from land A (a clay soil resting on a subsoil of chalky
loam), collected 1st of April, 1853. The same, collected 1st of May, 1853,

THEORETICAL AND PRACTICAL AGRICULTURE. Be

These drainage waters contain all the substances which
rain-water can dissolve out of the soil, and from their com-
position an idea may be formed of the quantity which a
plant during the period of its growth can possibly obtain
from such a solution.

Let us assume that on a 2} acre field 12 million pounds
of rain-water fall in a year, and that a third of this quantity
dissolves from the soil the same ingredients, in the same
proportions, as in the drainage waters analysed by Way.
Let us further suppose that these 4 million pounds of water
are, during the months of June, July, August, and Septem-
ber, completely absorbed by the roots of a crop of potatoes,
and again evaporated from the leaves; then it follows that
on four fields of 23 acres each, the whole crop of potatoes
would not receive a single pound of potash; on two others
of the same size they would obtain rather more than a
pound; and on a seventh 24 acre field, two pounds.

Now, from an average crop of potatoes on a 2} acre
field, there are obtained 408 lbs. of ashes, in which are
contained 200 Ibs. of potash.

If, again, we suppose a crop of beet to be grown on the
fields, of which Dr. Krocker analysed the drainage water,
and also assume that 4 million pounds of rain-water satu-
rated with mineral substances from the soil, are absorbed
by the crop, then these plants would receive from this
source on four different fields of 24 acres each, only 8 lbs.
each; on another, 16 lbs.; and on a third, 24 Ibs. of
potash.

after a heavy fall of rain (218 cub. in. on the square foot). @ Drainage water
from the same soil, mixed with water from a humus clay soil, with chalky
loam as subsoil, collected in October, 1853. q Drainage water from land B
(tile-drained, subsoil of chalky loam) collected in October, 1853. @ Water
passing through the water furrows from a heavy clay soil, collected in the
’ beginning of June. f The same, collected in the middle of August, after
heavy rain,
9%

84 THEORETICAL AND PRACTICAL AGRICULTURE.

Now, an average crop of beet from 24 acres weighs, with
leaves, about 1000 cwt., which contain 1,144 Ibs. of ashes,
of which 495 lbs. are potash!

The quantity of ammonia present in the drainage waters
analysed by Way is exceedingly small. It is not very
probable that one pound of ammonia in 3} million pounds
of water can exercise any marked influence on vegetation.

In a gallon (70,000 grs.) of Thames water taken from
four different places, the quantity of ammonia could not be
estimated. In the portion taken at Red-house, Battersea,
there were found 3 of ammonia, in 7 million parts of
water (Lieb. and Kopp’s Jahr., f. 1851, p. 658). By irri-
gation the 'hames water would undoubtedly produce a
considerable increase in the crops of hay on many mea-
dows, but certainly not by its ammonia, which is present in
this, as well as in all river waters in general, in only very
minute quantities.

The amount of phosphoric acid in drain, river, and ordi-
nary well-water, is exactly nil. Krocker found in drainage
water no phosphoric acid; Way obtained from three, only
traces; in two others, he found 12 parts of phosphoric acid
in 7 million parts of water; in a third, 8 parts, and in a
fourth, 6 parts of phosphoric acid, to the same quantity of
water.

From the action of soils already described, it follows
that plants must themselves play some peculiar part in the
absorption of their food. As organised living structures,
their existence is not quite dependent on external causes.

Did land plants receive their food from a solution, they
should only be able to take up what this solution contains
and brings to them in a certain time, and just in proportion
to the evaporation of the water from their leaves. It is
quite certain that in the process of assimilation, there is a
necessary co-operation between the water which soaks

THEORETICAL AND PRACTICAL AGRICULTURE. 35

through the ground, and the evaporation which takes place
from the leaves of plants; but the ground itself plays the
part of a guardian, protecting plants from a hurtful supply.
They select from the soil those substances which they re-
quire, but which can only pass into the interior of their
organisms by the co-operation of a cause which resides
within the rootlets.

We frequently find in meadows smooth lime-stones,
with their surfaces covered with a network of small fur-
rows. When these stones are newly taken out of the
eround, we find that each furrow corresponds to a rootlet,
which appears as if it had eaten into the stone.

It is very difficult to explain in what way plants act in
causing the solution of mineral substances. As a matter of
course, water is indispensable in the operation.

The difficulty of explaining the facts ought not at once
to deter us from investigating them in all their bearings,
and ascertaining the extent of their influence. Exceptions
exist in abundance.

_In the case of many water plants whose roots do not
come in contact with the ground, there must of course
exist other laws for the absorption of their mineral food.
As in the case of sea-plants, they must receive it from
the surrounding medium; for, wherever a plant grows, it
must find all the conditions necessary to its existence.

The investigation of duckweed (Lemna trisulca) offers in
this respect some points of interest. This plant grows in
still waters, in ponds and bogs, floating on the surface, so
that its roots are not in contact with the bottom.

From an artificial piece of bog in the botanic garden of
this place (Munich), a quantity of this plant was collected,
dried, incinerated, and the amount of ash determined.
From 10 to 15 litres (2} to 34 galls.), of the bog water
which was of a slight greenish tint, was at the same time

36 THEORETICAL AND PRACTICAL AGRICULTURE.

filtered and evaporated to dryness. The ashes, as well as
the residue from evaporation of the water, were submitted
to analysis. For comparison, the results are here placed
together. |

Ash of Duckweed. Evaporated residue from water of the

100 parts of dried duckweed, give cans Sade
16°6 parts of Ash. In 100 parts of 1 Litre gives 0°415 grm. salts
the Ash heated to low redness, are | (heated to low redness). In 100
contained :— parts of the salts are contained :—
Lime . : : . 16°82 : é : : ; . 35°00
Magnesia . " - - 5:08 ¢ ys . . : - » 12,264
Chloride of sodium . . . 5897 ; . . ° . - 10°10
Chloride of potassium . . 1°45 Sie ° . ._ ee
Potash . : ‘ ye te oe s : : . : owt
Soda . : ; t ._— Pht . . Ww ieee
Oxide of iron with traces of

alumina ‘ , mee Ge ‘ : , ° ? ~ 0-721
Phosphoric acid . PYG Si yes 3 ° oe” gn ee
Sulphuric acid . ‘ . a Oe : : : : : » Bare
Silica. . : : 12°35 Fish, ‘ F 43) pie ERE

The amount of mineral constituents of this plant, as well
as of the bog water, must strike others with the same as-
tonishment as it did the first observer. For we could not
presuppose that such a plant should far surpass the ma-
jority of land plants in the richness of its mineral con-
stituents. These were certainly taken up by the plant from
a solution; but in the process, it is highly deserving of
remark, that a power of selection was exercised by the
plant.

The comparison of the composition of the ash with the
salts left by the water shows, that all the mineral constitu-
ents of the latter, with the exception of the soda, are found
in the plant, but in very altered proportions; the water
contains 45 per cent. of lime and magnesia, the plant only
21 per cent. of both; the water contains 0°72 per cent. of

THEORETICAL AND PRACTICAL AGRICULTURE. 37

oxide of iron, the plant ten times this quantity. The dif-
ference in the phosphoric acid, potash, &c., is not less strik-
ing. The soluble mineral constituents were taken up by
the plant in the various degrees required for its vital pro-
cesses, and in no way proportional to the amount present
in the fluid.

The amount of mineral water present in this water is
remarkable. It is more than ten times greater than in
drainage water, and twenty-five to thirty times greater than
in well water. It resembles a mineral water in the kind
of salts it contains, and except in bogs is not likely to occur
in nature.

The amount of potash, phosphoric, sulphuric, and silicic
acids, and oxide of iron, which is found in it, can be easily
explained. In such a bog, the remains of dead plants are
by degrees collected, the roots of which have received from
the soil a quantity of mineral matter. These remains un-
dergo decomposition at the bottom of the pool, and their
inorganic elements are dissolved by the aid of carbonic
acid, and probably of organic acids, and remain in solution
in the water after the surrounding mud and earth have
been completely saturated with them. An experiment, in
fact, showed, that this potash water lost none of its potash
on filtration through earth taken at the distance of a foot
from the edge of the basin, whilst it was quickly removed
by earth taken from other spots.

In many places the mud from pools, still waters, and
many bogs, is highly esteemed as a fertilising agent. It is
evident that such mud acts like arable soil which has ab-
sorbed as much as it is capable of doing of the soluble
elements of food or manure brought in contact with it,
and a satisfactory explanation of its effect is found in the
quality of the bog water. Finally, it is conceivable that
water, in percolating through many field and garden soils,

38 THEORETICAL AND PRACTICAL AGRICULTURE.

in which the remains of plants have accumulated, and are
undergoing decomposition, will dissolve up many sub-
stances not usually found in mineral waters.

With the chemical properties of soils just described, there
is associated a physical quality, not less remarkable in its
nature and influence; viz., the power which they possess
of attracting moisture from the air, and condensing it in
their pores. It has been long known that earth possesses a
strong attraction for watery vapour, but it was to Babo
that we were first indebted for the proof that this attrac-
tion is only second to that of sulphuric acid, which pos-
sesses it in the highest degree. If we fill a flask with air
completely saturated with moisture at 20° C. (68° Fahr.),
the slightest diminution of temperature will cause the
moisture to be deposited in the form of dew; but if a
few ounces of earth dried at 35° to 40° C. (95° to 204°
Fahr.), be placed in the flask, the moisture will, in the
course of a few minutes, be so completely absorbed by it,
that no deposit of dew will take place at a temperature
even of 8° to 10° C. below 0° (14° to 18° Fahr.). The ten-
sion of the watery vapour has sunk from 17™ to less than
F baer)

In very moist air, soil loses its absorbing power for
moisture in proportion as it becomes saturated. When per-
fectly saturated it no longer absorbs any moisture from the
air. From air of the temperature of 20° C. (68° Fahr.),
containing watery vapour with a tension of more than 2™",
dry earth absorbs moisture, until an equilibrium is esta-
blished between the tension of the watery vapour in the
air, or the force which strives to maintain it in the gaseous
state, and the power of attraction in the earth which tends
to destroy this state.

A soil which has been saturated with moisture from the
air at a given temperature, gives off a certain portion to

THEORETICAL AND PRACTICAL AGRICULTURE. 39

drier air, or on an elevation of temperature. On the other
hand, it absorbs moisture from air still more moist, until
an equilibrium is established.

The processes of absorption and evaporation are accom-
panied by a most important phenomenon. By absorption
of moisture the soil is warmed, and by evaporation it is
cooled. If we suspend in a vessel with moist air, a linen
bag full of dry earth, with a thermometer sunk in it, the
quicksilver will be observed to rise in a few seconds. In
Babo’s experiment the temperature rose, in a specimen of
soil rich in organic matter, from 20° to 31° C. (68° to 88°
Fahr.); in a sandy soil to 27° C. (80° Fahr.). In like man-
ner, soil which had been partly saturated with moisture
from air at 68° Fahr. and 54° dew-point, when placed in
air completely saturated with moisture, caused the tempera-
ture to rise 3°6° to 54° Fahr. Such phenomena as these
must exercise a most decided influence on vegetation; for
though the above extremes in the elevation of temperature
are seldom observed, the intermediate points are of frequent
occurrence.

When in a hot summer the surface of the ground is dried,
and there is no replacement of moisture by capillary attrac-
tion from the deeper strata, the powerful attraction of the
soil for the vapours of water in the air provides the means
for supporting vegetation.

The vapour of water which is thus condensed by the soil
is derived from two sources. During the night the tempe-
rature of the air falls; the tension of its watery vapour be-
comes less; and then, without the temperature of the air
falling to the dew-point, there follows, through the attrac-
tion of the soil, absorption of moisture (with ammonia and
carbonic acid), accompanied by evolution of heat which
-moderates the cooling of the ground from radiation. In
rainless tropical regions, particularly, this phenomenon

40 THEORETICAL AND PRACTICAL AGRICULTURE.

must be of the most palpable influence. If in our tempe-
rate climate its effect is not so striking as in these regions, it
is nevertheless not to be regarded as altogether inappreci-
able. As condensation takes place slowly, the elevation
of temperature here cannot amount in many cases to more
than fractions of a degree. But it is precisely those frac-
tions which promote the better growth of many plants.
The soil by means of this property of absorption becomes
warmer, and maintains its temperature more equably than
it would otherwise do.

A second source from which the dry soil derives by
absorption its moisture, is presented by the deeper lying
moist strata. From these a constant distillation of water is
taking place towards the surface, accompanied by a corre-
sponding evolution of heat in the upper strata on its absorp-
tion. By drainage the water, which rises by capillary
attraction, being placed at a greater depth, the dry soil now
receives from the lower strata a quantity of moisture in the
form of vapour, which supplies the wants of plants, and at
the same time raises the temperature of the ground.

In the above facts we recognise one of the most remark-
able natural laws. The outermost crust of the earth is destined
for the development of organic life, and us broken particles are
endowed, by the wisest arrangement, with the power of collecting
and retaining all the elements of food which are essential for the
purpose. This power preserves to the productive soil, even
in apparently the most unfavourable circumstances, the con-
ditions of fertility either contained therein, or bestowed
upon it.

LETTER IV.

The Belief in the value of Humus no longer exists; its Action now ascertained
—Effect of the Salts of Ammonia not dependent on their Nitrogen—The
action of Nitrates like that of the Salts of Ammonia—Experiments with
Nitrates and Chlorides—Experiments with Salts of Ammonia alone, and
with the addition of Common Salt—Solubility of the Earthy Phosphates in
solutions of Chlorides of Ammonium and of Sodium, and of Nitrate of Soda
—Experiments with these Salts—Their Solvent Action similar to that of
Carbonic Acid water—The Salts of Ammonia are decomposed in the soil ;
their twofold action—Difference in the Comportment of Salts of Potash and
of Soda in the Soil—Potash extracted by Sulphate of Ammonia from silicates
—Application of the Action of Chili Saltpetre, Salts of Ammonia, and
Chloride of Sodium to explain the increase of fertility in the soil, and the
Nutrition of Plants.

UP to a few years ago, scientific agriculture taught, and all
practical men firmly believed, that the productiveness of a
soil was dependent on the quantity of humus, or carbonaceous
remains of a preceding vegetation, contained init. Without
raising doubts on the efficacy in certain cases of the organic
matter in farm-yard manure, it may be asserted that nobody
who possesses any knowledge of the matter, now believes
that the produce of a field in carbonaceous substances bears
any proportion to the amount of humus in the soil, and that
its fertility can in reality be estimated, as was formerly sup-
posed, by this humus.

We have now obtained more exact information on the
part played by humus in vegetation, and can predict in what
cases its presence will be beneficial or hurtful. We know
that it is only useful when the soil contains in sufficient
quantity the fixed mineral constituents serviceable to plants ;

42 THEORETICAL AND PRACTICAL AGRICULTURE.

and that it is without action when these are wanting By
its decomposition in the soil, humus forms a source of car-
bonie acid, by which the fixed elements of food are rendered
soluble, and capable of being distributed in all directions.

In his remarkable experiments on the action of the salts
of ammonia, Lawes obtained in twelve years from an acre
of the same field, by the use of mineral substances and salts
of ammonia, produce in wheat and straw, amounting to
51,995 lbs. From a second acre manured in the same way,
the return reached 53,182 lbs. By the use of pure mineral
manures, there was obtained from these two fields a greater
amount of produce, to the extent of 18,525 Ibs. in one case,
and 19,718 in the other, than from an unmanured field of
similar size. It is quite certain that by the employment of
farm-yard manure, a similar, if not higher, return would
have been obtained from both fields. There can, however,
be no doubt that in both cases the salts of ammonia had
taken the place, and produced the effect of the decaying
organic matter of this manure; and it is not improbable
that the same cause was in operation in augmenting the
produce.

It has been abundantly proved by facts, that the action
of the salts of ammonia is no way proportional to the amount
of nitrogen in them; hence it is evident that the salts as
such, or the acids of the salts, must take part in the effect
produced. The precise nature of this co-operation is, how-
ever, not yet distinctly made out; and from this cause has
arisen the great discordance in the views of the peculiar
action of the salts of ammonia. Whilst some hold that the
action can only be referred to the nitrogen, because the acid
can be changed without thereby materially altering the
effect ; others assert that the soil already contains so much
ammonia, that the increase of produce cannot be attributed
to the small quantity of nitrogen added in the salts of

THEORETICAL AND PRACTICAL AGRICULTURE. 43

ammonia. They maintain that an acre of ground which
contains in its upper ten inches of soil 10,000 Ibs. of
ammonia or nitrogen, could not have its fertility increased
two-fold by the addition of 30 to 60 lbs. of ammonia. As
in such a soil there was no want of nitrogen, the cause of
the increased fertility must be sought for in something
else. .

The case is much the same with the action of nitrates as
with that of the salts of ammonia. Nitrate of soda exer-
cises a powerful effect, in certain cases, on the increase of
grain and straw, and in others it is valueless. The experi-
ments of Kuhlmann have shown that the bases also of these
salts play some part in the action. From a meadow ma-
nured with 250 kilogrammes (550 lbs.) of nitrate of soda,
an increase of crop to the amount of 2053 kilo. (4516 lbs.),
per hectare (24 acres), was obtained; whilst from another
portion of the same meadow, to which was applied the
same quantity of nitrate of lime (containing 14 per cent.
more nitric acid), there was an increase of only 693 kilo.
(1524 lbs.). Consequently the produce from nitrate of lime
was # less than from the soda salt. If we ascribe the
increase in the crop to the nitric acid, then the effect of
the two salts is quite incomprehensible.

The action of common salé appears in many cases equally
incomprehensible. In 1846, Kuhlmann obtained from 200
kilo. (440 Ibs.) of sulphate of ammonia an increase of hay,
amounting to 2583 kilo. (5572 lbs.); a similar quantity of
sulphate of ammonia, with the addition of 183 kilo. (292
lbs.) of common salt, gave an increase of 3173 kilo. (6980
lbs.) of hay. There were consequently 640 kilo. (1408 Ibs.)
more hay obtained by the addition of the common salt,
than from the employment of the sulphate of ammonia
a.one.

It might be supposed, that the want of a chlorine com-

dt THEORETICAL AND PRACTICAL AGRICULTURE.

pound, which is contained in not inconsiderable quantity in
meadow plants, was the reason, in the case of the common
salt, of the increase of produce; but a similar difference, as
in the above cases, was found in two other experiments,
which Kuhlmann made, in 1845 and 1846, with sal-ammo-
niac alone, and with sal-ammoniac and common salt. The
piece of meadow manured with 200 kilo. (440 lbs.) of sal-
ammoniac gave in the two years 3700 kilo. (8140 lbs.) per
hectare (24 acres), more hay than a piece of the same extent
which was unmanured. From another portion, to which
were applied 200 kilo. of sal-ammoniac and 200 kilo. of
common salt, 5687 kilo. (12,511 lbs.) of hay were obtained.
Hence, by the use of common salt, there was an increase
of 1087 kilo. (2391 Ibs.), or a half more than from the sal-
ammoniae alone. 200 kilo. of common salt alone, without
sal-ammoniac, produced an increase of 1606 kilo. of hay,
the difference between the two numbers (1987 and 1606
kilo.) is not great enough to exclude the idea, that each
salt has acted, just as if the other had not been present, or,
in other words, that each salt has a special action of its
own.

In the summer of 1857, the effect of salts of ammonia by
themselves, and mixed with common salt, on summer bar-
ley, was tried by the General Committee of the Agricul-
tural Society of Bavaria, in a series of experiments made
at Bogenhausen, in the neighbourhood of Munich. For
this purpose, 18 plots, each of 1914 square feet in extent,
were marked off in a field which had gone through the
usual rotation of crops, having been, three years previously,
manured with common farm-yard manure, and having
borne rye, and then two crops of oats.. Four of these plots
were manured with salts of ammonia; one remained unma-
nured; to four others were applied the same quantity of
ammonia salts, and at the same time, to each 3080 grm.

THEORETICAL AND PRACTICAL AGRICULTURE. 45

_(64 Ibs.) of common salt. Hach plot received the same
amount of nitrogen in the ammonia salts.

In estimating the quantity of manuring matter to be
employed, it was assumed that 400 Ibs. ( = 440 lbs. Eng.)
of guano per English acre, corresponded to the full measure
of farm-yard manure usually applied; this gives twenty
pounds of guano for one of the plots. A good sample of
guano was selected for the experiments, and on being sub-
mitted to analysis, was found to consist of 14°53 water,
33°38 ash, and 52°10 organic matter, of which 15°39 was
ammonia. ‘Twenty pounds of this guano, therefore, con-
tained 8°07 Ibs. of ammonia. In the ammonia salts used,
analysis gave in

Carbonate of Ammonia : ‘ 3 29°84 per cent. Ammonia.
Phosphate : . , 21°96 " Bi
Nitrate - : : . 19°11 i “i

In correspondence with this percentage of ammonia,
there were applied to two of the plots, I. and V., 103 Ba-
varian pounds ( = 13 lbs. Eng.) of carbonate of ammonia ;
to two others, IT. and VI., 74 lbs. (= 9 lbs. Eng.) of nitrate
of ammonia; to two others, III. and VII., 12 lbs., (= 142
Ibs. Eng.) phosphate of ammonia. ‘T'wo plots, IV. and
VIIL., received each 12 lbs. ( = 14% Ibs. Eng.) of crystal-
lised sulphate of ammonia; another, 20 lbs. (= 24% Ibs.
Eng.) of the analysed guano. The plots, V., VI., VIL,
VIIL., received each at the same time 3080 grm. ( = 63 Ibs.
Eng.) of common salt. I will here communicate these ex-
periments in full, as they offer other points of interest, in
addition to the action which must be ascribed to the com-
mon salt.

Produce of barley (grain and straw), from the four plots
manured with ammonia salts alone :—

46 THEORETICAL AND PRACTICAL AGRICULTURE.

GRAIN. STRAW.
grm. lbs. Eng. grm. Ibs. Eng.
1g =" Goo0 — iu 16205 = 356
fi» 4 - ==119470) 18% 16730 = 368
III. he ‘ - -==)1280 <= 160 17920 = 39°5
IV. - " == (69 gual), 1s28i, =,40-2

The unmanured plot gave = 6825 15:0 18375 40°4

Produce of barley (grain and straw) from four plots
manured with ammonia salts and common salt :-—

GRAIN. STRAW.
grm. Ibs. Eng. grm. Ibs. Eng.
Vis . = 14550 = 32°0 27020 = 59°5
VI. = 16510 = 36°85 36645 = 80°6
VIL == 9887: == 217 24832 = 54°6
VIII. = 11130 = 246 27969 = 61°

Increase of produce in plots V. to VIII., manured with
common salt and salts of ammonia, above that of plots L
to IV., manured with salts of ammonia alone :—

GRAIN. STRAW.
grm. lbs. Eng. grm. Ibs. Eng.
i be - E == <eeom = tae 10814 = 23°8
WEA, C 3 = 7770 = 17-0 19915 = 43°8
VIL. . ‘ = 2607 = 6:7 6912 = 15:2
VIIL. é a f Ss 4ub8,= 19:3 782 = 2b

In instituting experiments in practical agriculture with
manures, the increase of crop is generally the only object
kept in view. If this object be attained, the experiments
are said to be successful. In this sense, the above experi-
ments, both with and without common salt, are unsuccess-
ful; for the returns scarcely reach average crops. The
object with which they were made was not, however, to
obtain a greater crop than the average, but to investigate
the action of the salts of ammonia alone, and with the

THEORETICAL AND PRACTICAL AGRICULTURE. AT

addition of common salt. In this respect they agree suffi-
ciently to banish all doubt as to the physiological iaport-
ance of common salt to the Bogenhausen fields. In every
case the crop was increased by the addition of common
salt. Common salt when used with carbonate of ammonia,
doubled the produce of grain ; and with nitrate of ammonia,
it raised the return of corn 90 per cent.,—and of straw 120 —
per cent.

As the mixture of nitrate of ammonia and common salt
contains the elements of nitrate of soda, a counter experi-
ment with the latter salt on a plot of the same field, made
at the same time, is of much interest. The plot manured
with 16 lbs. (= 19% lbs. Eng.) of nitrate of soda, gave
12820 grm. (= 27 lbs.) grain, and 82480 grm. (= 71% lbs.)
straw; and by the addition of 54 lbs. (= 6% lbs. Eng.) of
common salt, the grain increased to 17920 grm. (= 393
Ibs.), and the straw to 85780 grm. (= 78% Ibs.). Common
salt had, therefore, also increased the action of Chili salt-
petre. A mixture of these two salts produced a still
higher yield of grain, than a mixture of common salt
and nitrate of ammonia, which contained the same pro-
portion of nitrogen. The experiment with 20 lbs. (= 242
Ibs.) of guano, on a plot of the same size, gave 17200
grm. (= 388 lbs.) grain, and 33320 grm. (= 7384 Ibs.
straw.

It is quite certain, that in the action of the guano, which
produced the crop next highest after the Chili saltpetre, an
unmistakable part was played by the ammonia contained
init. On the other hand, however, the experiments with
carbonate and nitrate of ammonia show, that a quantity of
ammonia, or nitrogen, equivalent to that in 20 lbs. of
guano, and employed under the same conditions, was
almost without effect.

I will not, by further pursuing this subject, weaken the

48 THEORETICAL AND PRACTICAL AGRICULTURE.

significance of the most important fact brought out by
these experiments with the salts of ammonia, viz., that
common salt, in reality, exercises a favourable action on
the growth of straw plants in the Bogenhausen fields, and
increases the mass of vegetable matter in them.

This fact is indeed not new in agriculture; but in a num-
ber of cases, in which common salt has been shown to be a
useful addition to other manures, its action has not been
sufficiently distinct and decided; and it is a rule in natural
inquiries that a fact must first of all be firmly established,
before we proceed to seek its explanation.

The action of common salt is evidently very similar to
that of the salts of ammonia and nitrate of soda; but if we
refer the effect of these last two substances to their nitrogen,
because ammonia and nitric acid are food for plants, then
this explanation will not hold good for common salt. For
neither this salt nor chlorine enters as an element into the
structure of plants, and it cannot be asserted that either of
them is necessary, although both are frequently met with
as constituents of the ashes of plants.

The most recent observations on the comportment of the
soil towards the food of plants show how slight is the
knowledge we possess of their mode of nourishment, and
of the part which the soil, by its physical condition, plays
in it. The comportment of the salts of ammonia, of
chloride of sodium, and of nitrate of soda, towards the
earthy phosphates in the soil, may perhaps assist us in
throwing some light on their action, or on one of their
actions, on the growth of plants.

Like carbonic acid water, the sulphate, as well as other
soluble salts of ammonia, possesses the property of render-
ing the earthy phosphates soluble in water.

We know of no other way in which the earthy phos-
phates are dispersed through the soil than by means of

THEORETICAL AND PRACTICAL AGRICULTURE. 49

carbonic acid water. If it is true that one of the chief
effects of humus, or the decaying remains of plants in soils
or in manures, consists in its forming a source of carbonic
acid, with which the air and water in the ground is en-
riched ; if itis also true that this carbonic acid water ren-
ders the earthy phosphates soluble, and thus contributes to
their distribution in the soil, then there can be no doubt
that the salts of ammonia, which possess the same solvent
property, can in this respect replace the organic matters,
and thus exert an equally favourable influence on the
growth of plants.

The same solvent property is also possessed among the
salts of soda by Chili saltpetre and common salt. It has
been recently shown that these two salts, even in the most
dilute solutions, dissolve earthy phosphates to a very appre-
ciable extent, and that consequently they must play a part
in the process of the nutrition of plants, similar to that
which is ascribed to carbonic acid water (to the humus) and
to the salts of ammonia.

From direct experiments it appears, that 100 kilo (= 220
Ibs.) of sulphate of ammonia in solution in 45,000 litres
(= 9,900 galls.) of water can dissolve 3600 grm. (=7°9 lbs.)
of bibasic phosphate of lime (PO,;, 2CaO, aq.) such as
exists in bones that have been acted on by sulphuric acid ;
or, in other words, 100 Ibs. of sulphate of ammonia in
4,500 gallons of water—dissolve nearly 4 lbs. of phosphate
of lime. In like manner 100 lbs. (=123 Ibs. Eng.) of com-
mon salt, in 50,000 litres (= 11,000 galls.) of water, dis-
solve 3,300 grm. (= 74 lbs.) of bibasic phosphate of lime;
and 100 kilo. (= 220 lbs.) of nitrate of soda, in 33,400
litres (= 7,348 galls.) of water, dissolve 2,630 grm. (= 53
Ibs.) of the same phosphate.

Tribasic phosphate of lime (PO,, 8CaO) is much less
soluble in these fluids.

3

50 THEORETICAL AND PRACTICAL AGRICULTURE.

‘ issolve of tribasi
100 kilo. (220 lbs.) of In solution in water in anenie of Meche,

POs, 3 CaO.

Sulphate of ammonia,/54,000 litres (=11,880 galls.)) 3400 -grm. (=74 Ibs.)
Common salt........|50,000 “ (=11,000 “ )} 1500 “ (=8% “ )
Nitrate of soda....... 133;300 Wifes 4826 « “911200 >. (eneeey

The seeds of the cereals, particularly wheat, contain
phosphate of lime, and in preponderating quantity phos-
phate of magnesia. In many kinds of wheat the quantity
of phosphate of magnesia is four times, often ten times,
greater than that of the phosphate of lime; and in like
manner in the grain of rye, oats, and barley, the magnesia
salt exceeds very greatly the phosphate of lime. These
proportions are so constant that they cannot be ignored in
the cultivation of these plants. ‘The comportment of the
salts above-mentioned towards phosphate of magnesia and
ammonia, and phosphate of magnesia, appears, therefore,
of special interest.

Dissolve of phosphate

100 kilo, (220 lbs.) of In solution in water, in of Magnesia, POs
gO.
gO.

Nitrate of soda......| 33,300 kilo. (= 73,260 Ibs.) | 2160 grm. (=4% Ibs.)
Common salt......../ 50,000 “ (=110,000 “)| 3790.“ (==8$ “ )

The solubility in the same fluids of phosphate of magne-
sia and ammonia is still greater.

Dissolve of phosphate

100 kilo. (220 Ibs.) of In solution in water, in sinbie eon M0,
4VU.

Sulphate of ammonia.| 33,300 litres (= 17326 galls )| 4113 grm.(= 9 Ibs.)
Common salt........ 50,000 “ (=11,000 “ )} 6170 “ (=133
Nitrate of soda......| 33,300 “° (= 7326 “ )/ 4655 “- (=103 “

THEORETICAL AND PRACTICAL AGRICULTURE. 51

The quantity of the earthy phosphates taken up by the
above fluids does not rise in proportion with the amount
of salts in solution, but rather on the contrary with the
dilution of these fluids.*

It is quite conclusive from these facts, that water con-
taining a very small quantity of common salt, nitrate of
soda, or a salt of ammonia, acquires thereby the power,
(which alone it does not possess, or only in a slight degree)
of dissolving phosphoric acid, in the form of earthy phos-
phates. These feeble solutions, therefore, react towards
earthy phosphates like solutions of carbonic acid in water.
100 kilo. (= 220 lbs.), for example, of sulphate of ammonia
produce the same solvent effect on phosphate of lime as
4720 litres (= 103884 galls.) of carbonic acid in solution in
water; and 100 kilo. of common salt dissolve as much
phosphate of magnesia and ammonia as a watery solution
of 8456 litres (= 7603 galls.) of carbonic acid.

Direct experiments prove, that a very dilute solution of
the same salts, take up phosphoric acid from a soil which
contains earthy phosphates in excess, and that this dissolved
acid is again given up by this solution to a similar soil
which is not already saturated with phosphoric acid.

If we submit to a close scrutiny the comportment of the
salts of ammonia, nitrate of soda, and common salt towards
soils, we find that not one of these salts acts in the same
form in which it has been added to the ground.

* 1000 C. C. of fluid, con- Dissolve of POs, 2Mg0,

ining at 67° F WHO. 5, ag For 1 grm. of salt,
2°2 grm. NH:OSOs 76°7 milligrm, 34°9 milligrm.
3° sé “é 113°0 “ 87°6 ‘<é

10° rT ts 147-0 “ 14:7 “

52 THEORETICAL AND PRACTICAL AGRICULTURE.

The salts of ammonia are immediately decomposed by
the soil; the ammonia is retained, whilst the acid enters
into combination with lime, magnesia, alkalies, or, in short,
with any basic substance in immediate contact and capable
of combining with it.

The action of these salts is therefore of a two-fold nature.
On the one hand, they enrich the soil with ammonia; on
the other, their acid gives rise to new compounds which
come into operation. The alkalies and alkaline earths
which combine with the acid acquire thereby a greater
degree of solubility, and are more readily diffused through
the soil. If the ground is rich in magnesia or lime, the
salts of these bases are formed; but their influence, with
the exception of that of gypsum, on certain plants cannot
be estimated very high. The use of sal-ammoniac, instead
of sulphate of ammonia, gives rise to chloride of magne-
sium, and chloride of calcium, which act rather unfavoura-
bly than otherwise on vegetation. That salts of these
bases are generated by the action of soils on salts of ammo-
nia, and that the new salts exert no particularly favourable
influence on the increase of produce, are facts on which no
doubt can rest.

If, however, portions of the soil containing in some
places phosphate of lime or of magnesia in the form of
coarse grain, or powder, or bone earth, come in contact
with these ammoniacal fluids, then there follows solution
of these earthy phosphates, and their consequent diffusion
through the soil.

Potash salts resemble those of ammonia in the rapidity
of their decomposition in contact with soils; but the com-
portment of soda salts is quite different.

On slowly filtering a solution of nitrate of soda (contain-
ing one-fifth per cent. of salt) through an equal volume of
Bogenhausen loam, half of the salt passes through unab-

THEORETICAL AND PRACTICAL AGRICULTURE. 5a

sorbed, whilst the other half is converted into nitrate of
lime and nitrate of magnesia. Under the same circum-
stances three-fourths of a solution of chloride of sodium
remain undecomposed.

If, therefore, a field is manured with nitrate of soda or
common salt, and the soil becomes saturated with a dilute
solution of these salts formed by rain, a great portion of
them will remain unchanged in the ground, and must exer-
cise on the moist soil an action which, though in itself
feeble, becomes powerful by its continuance. ,

Like the salts of ammonia, or a watery solution of car-
bonie acid produced by the decay of organic matter in
manures, a solution of these salts, wherever they come in
contact with spots containing accumulations of earthy phos-
phates not fixed by the soil, must become saturated with
these phosphates, and thus convert them into a condition
in which they can be diffused through the ground. If the
earthy phosphates, when thus diffused in solution, come in
contact with other portions of soil not yet saturated with
these salts, those portions absorb and fix these earthy phos-
phates, and the chloride of sodium or nitrate of soda
retains, a second time, or more frequently, the power of
exercising the same solvent and distributing action over
the earthy phosphates until the ultimate and complete con-
version of the chloride and nitrate into a lime or magnesia
salt.

When we consider how much the fertilising effect of
bone earth is increased by the greater solubility and capabi-
lity of distribution in the soil communicated by the action
of sulphuric acid, we cannot too highly estimate the signifi- ,
cance of the properties, just described, of the salts of ammo-
nia, chloride of sodium, and Chili saltpetre.

The most abundant application of earthy phosphates in
coarse powder, can in its effects bear no comparison with a

54 THEORETICAL AND PRACTICAL AGRICULTURE.

much smaller quantity which, in an infinite state of divi-
sion, is dispersed through every portion of soil. - A rootlet
requires at the spot where it touches the soil a most minute
amount of food; but it is necessary to its functions and its
very existence, that this minimum be found exactly at this
spot. For if the food of plants be not soluble in water,
then is any excess at any other spot as valueless to the func-
tion of nutrition of this rootlet as if it did not exist at all
in the soil. Now, the salts of which we have been speak-
ing, possess the property of conveying these elements of
food from the spot in which they exist in superabundance
to others in which there is a deficiency; and even though
their elements contributed in no way directly to the pro-
cess of nutrition, yet, these salts must nevertheless exercise
a marked influence on the increase of produce.

When the sulphate of ammonia and Chili saltpetre have
been completely transformed into lime and magnesia salts,
and the chloride of sodium into chloride of calcium and
chloride of magnesium, this action then ceases; and a second
dose of these salts is then necessary to reproduce the action.

If the effect of the salts of ammonia depends on the am-
monia, we can scarcely comprehend why, after a large
application of them, that portion which has not acted
during the first year should not in the second come into
operation, since this latter portion is presented in the soil
to plants in the same form as the portion which produced
its effect during the first year.

Sulphate of ammonia produces on alkaline silicates a
reaction similar to that on earthy phosphates. If this salt,
in very dilute solution, is brought in contact with soil satu-
rated with silicate of potash, and which does not give up a
trace of its potash to water alone, it instantly dissolves a
certain quantity of this alkali, which may be easily detected
by the ordinary re-agents.

THEORETICAL AND PRACTICAL AGRICULTURE. 55

It is evident that the agriculturist, by the proper appli-
cation of the chemical action of common salt, Chih saltpe-
tre and ammonia salts, accomplishes the same object as by
the mechanical operation of ploughing, and by the action
of the atmosphere in fallow.

We should be committing an error, if, judging from
similarity of solvent properties, we concluded that common
salt must have the same effect as a corresponding quantity
of nitrate of soda. We know that, as a rule, in these cases,
the common salt is converted into chloride of calcium, and
the Chili saltpetre into nitrate of lime; and the. experi-
ments of Kuhlmann have taught us, that chloride of cal-
cium by itself is absolutely ineffective, or rather is hurtful
in the cultivation of plants, whilst nitrate of lime contri-
butes materially to the increase of a hay crop. Nitrate of
soda, consequently, acts favourably in two ways; chloride
of sodium only in one. Further, land plants can bear a
considerable quantity of nitrates of soda in the soil, whilst
chlorine compounds, beyond a certain very narrow limit,
are decidedly hurtful.

We designate as manures all substances which increase
the produce of our fields, without knowing whether many
of these may not simply act, by rendering the food already
existing in the soil more capable of absorption and assimi-
lation. ‘The simple fact of their favourable influence on
vegetation, is not yet a proof that they have acted directly
as food. We compare the work which the plough performs,
to the mastication of food, for which nature has provided
animals with a particular instrument; and, as may be seen
from the experiments described above, many substances,
such as common salt, nitrate of soda, and ammonia salts,
independently of the action which is due to their-own ele-
~ ments, play a peculiar part, which may be compared to the
digesting action of the stomach, and in which they can

56 THEORETICAL AND PRACTICAL AGRICULTURE.

partly replace each other; and inasmuch then as they pre-
pare the food existing in the soil for the process of nutri-
tion, and render it more fit for assimilation, they must
necessarily exert a powerful influence on the growth of
plants.

We can now understand why these salts exercise a
favourable action in the cultivation only on certain soils,
and why on a second or third application of them, the same
effect is only partially, or not at all reproduced.

An agriculturist in possession of fields containing abund-
ance of phosphates, but unequally distributed through them,
would, were all other conditions the same, undoubtedly
increase the activity of these phosphates, and thereby aug-
ment the produce of his fields, if he possessed the means
of withdrawing the basic phosphates from the soil and
restoring them in the form of superphosphate. These
means he actually employs, when he manures his fields
with Chili saltpetre, ammonia salts, or chloride of sodium.

LETTER V.

No free Ammonia in the Soil—The amount of Food obtained from the soil
by plants is in proportion to the absorbent Root-surface—The early deve-
lopment of Roots due to the accumulation of Nourishment in the surface
soil—Estimations of the quantity of Ammonia in our cultivated fields—A
deficient crop not due to the Absence of Ammonia in the soil—Experi-
ments with salts of Ammonia; the crops only slightly increased thereby—
Increase of produce due to accompanying Minerals—Experiments of Lawes
and Kuhlmann with salts of Ammonia, &c.—The fertility of a field depend-
ent on the sum of the Mineral matters in it—The activity of these Minerals
increased within a given time by the Salts of Ammonia—The soil more
rapidly exhausted by their use unless there is a restoration to it of the
removed Mineral matters.

THE soil contains a certain quantity of nitrogen in the form
of ammonia and of nitrogen compounds derived from plants
and animals.

The observations of Thomson and of Huxtable, and par-
ticularly the valuable memoirs of Way, have established
the fact, that the carbonate of ammonia of rain water and
of manures, and that existing in ammonia salts, are absorbed
and so firmly fixed by the soil that no free ammonia can
be present in it. As neither pure nor carbonic acid water
can withdraw this fixed ammonia from the soil, it is self-
evident that, in the nutrition of plants, the rootlets must
extract it directly from. the soil.

If we now imagine that plants receive all the nitrogen
they require for their development not from the air but
from the soil, it is clear that every portion of soil must con-
tain the necessary quantity of ammonia or nitrogen for their
vital processes; and plants would not attain their maxi-

3*

58 THEORETICAL AND PRACTICAL AGRICULTURE.

mum development, if they found in those portions less
than the roots could absorb and the plant appropriate.
Were all other conditions for the formation of grain pre-
sent, they would then produce a smaller quantity, or grain
of a lighter weight.

The productiveness of a field, in so far as it is dependent on
nitrogen, would be in proportion to the sum of this element
contained in the soil, and to that portion of this sum which
is present in each transverse section of the soil from the
surface downwards. In whatever spot the rootlets cannot
find nitrogen, they would therefore at that spot absorb none.

From two fields, containing from the surface downwards
the same quantity of nitrogen, and supposing all the other
conditions of growth to be given, it will be found that two
plants will receive unequal quantities of nitrogen, if their
absorbent surface of rootlets is unequal in extent. The
plant with double extent of absorbing root surface will take
up twice as much nitrogen as the other. This proportion
holds good for all the elements of food in the soil.

From a field which contains only half the quantity of
food which is present in another, a plant with a double pro-
portion of rootlet surface will receive as much nourishment
as a plant with only half the rootlet surface obtains from
the second field.

These propositions are self-evident, and may afford an
explanation in many cases of one of the leading effects of
manures on our fields. For, an accumulation of nourishment
in the upper layer of the field enables plants, during the first
period of their development, to send out ten-fold, perhaps
a hundred-fold more absorbing rootlets than they otherwise
would have done, and their later growth will be in propor-
tion to the greater number of rootlets thus gained, by which
they are enabled to seek and appropriate the food distributed
sparingly throughout the deeper layers.

THEORETICAL AND PRACTICAL AGRICULTURE. 59

We possess as yet no investigation of the number of
rootlets and the extent of their absorbing surface in our
cultivated plants, and cannot therefore with any degree of
certainty fix the quantity of ammonia which must neces-
sarily be present in each transverse’section of soil to satisfy
the full requirement of nitrogen in the different classes of
plants.

If we now accept, on the grounds mentioned in the next
letter, that each square millimetre of the transverse section
of a field must contain $4 a milligramme of ammonia, in
order to furnish to the rootlets of a wheat plant all the
nitrogen which it requires for its full growth, it follows that
10,000 Ibs. (or 0°12 to 0°13 per cent.) of ammonia must be
present in the soil of a hectare (24 acres) of land within the
depth reached by the chief roots.

If we compare with the above the amount of ammonia
or nitrogen, ascertained with certainty by numerous analyses
to exist in the soils of different countries, it appears that a
depth of even ten inches of the greater number of our cul-
tivated fields furnishes much more than this quantity.

As our cultivated plants undoubtedly absorb through
the leaves as much nitrogenised food in the form of ammo-
nia and nitric acid from the air as well as dissolved in rain
and dew, as uncultivated plants which receive no nitrogen-
ised manure from the hands of man; we can therefore
conceive that the agriculturist will seldom have to seek the
reason of his poor crops in a deficiency of ammonia or
nitrogenised food alone, and that he must first of all direct
his attention to certain other conditions in order to improve
his harvest.

A knowledge of the quantity of ammonia or nitrogen in
a soil is, therefore, not sufficient to enable us to judge of
its facility or capacity for production. For, even though
a better crop be obtained from many fields by the applica-

60 THEORETICAL AND PRACTICAL AGRICULTURE.

tion of ammonia, on by far the great majority of others, the
largest quantities of this food produce no effect; because
though the nitrogen must indeed be there, and takes part
in.the formation of the vegetable mass, yet it produces by
itself no effect when the conditions are awanting which
render it active.

The experiments of Schattenmann made in 1848 in
Alsace, are in this respect very instructive. Wheat fields
manured by him with salts of ammonia gave a smaller return
of grain than another portion of the same land which had
received none of this manure. In like manner the experi-
ments of the General Committee of the Agricultural Soci-
ety of Bavaria in 1857 (see p. 46), show that the produce
of barley in grain and straw was rather reduced than other-
wise in a field to which carbonate of ammonia had been
applied; and that the use of sulphate, phosphate, and nitrate
of ammonia raised the produce only a few per cents. A
quantity of guano containing the same amount of ammonia
as these salts gave on the same field three times as much
grain, and twice as much straw as the unmanured land.

It is obvious that the proximate cause of the powerful
action of the guano in this case must be sought for in those
matters which in it accompany the ammonia; for, as we
nave just stated, a quantity of ammonia equal to that of
the guano produced no marked effect on the same field, in
the same year, and with the same kind of crop.

It is clear that a field which either originally contained,
or has had added to it, a sufficient quantity of the substances
that accompany ammonia in guano, would, on the subse-
quent application of the salts of ammonia, produce an
equally good crop as it would have done with the guano,
and better than would have been the case without the
aid of the ammonia. In such a case, however, it would be
a hasty conclusion to ascribe the higher return to the action

THEORETICAL AND PRACTICAL AGRICULTURE. 61

of the ammonia alone, because in the years of greater
increase the salts of ammonia had been exclusively used.

The experiments of J. B. Lawes, in the years 1844 to
1855, give practical proofs of the truth of this view. He
manured a wheat field with superphosphate of lime (560
Ibs. per acre), and with silicate of potash (220 lbs.), and in
the eleven following years only with ammonia salts (sul-
phate of ammonia and chloride of ammonium) and reaped
on an average from it a half more grain and straw than
from another piece of unmanured land of the same
size which, during the same years, had been sown with
wheat.

These results fully agree with those of Kuhlmann’s ex-
periments in 1844 to 1846, with salts of ammonia on a
meadow.

From a meadow which had been manured with sal ammo-
niac, he obtained an increase of 645 parts of hay for every
100 parts of the salt employed. In the same year, from a
second meadow, to which sal ammoniac had been also
applied, but with the addition of phosphate of lime, he
reaped 1666 parts of hay for every 100 parts of sal ammo-
niac; consequently the produce was 23 times more than
was obtained without phosphate of lime.

The importance of the addition of fixed mineral food ta:
the increase of crops, and to the duration of the fertility of
our fields, will at once be evident to the most prejudiced:
from another series of experiments by Lawes.

During the period that the experiments already mentioned
were in progress, Lawes had applied, on a third field, for
three years, fixed mineral matters, and for nine years, salts
of ammonia; in 1846 it remained unmanured. This field
had, therefore, received two applications of ammonia salts
‘less, and two of mineral manures more than the second

field.

62 THEORETICAL AND PRACTICAL AGRICULTURE.

The following was the produce per acre of the three
fields :—

Grain and Straw.
I. Unmanured field produced : : : . 984,272 Ibs.

II. Field manured 1 year with mineral ssid and i
11 years with salts of ammonia t esis

III. Field manured 3 years with mineral aie eves 3
and 9 years with salts of ammonia : Z ase

Although the third plot had received above 700 lbs. of
ammonia salts per acre less than the second, its produce
had nevertheless increased by half a crop. These facts
show in the most undoubted manner, that even on ground
so rich in the fixed constituents of food for wheat, as to
furnish during twelve continuous years, without any ma-
nure, a yearly medium crop of 2856 lbs. of grain and straw,
the greatest supply of salts of ammonia, with an insufficient
replacement of the mineral substances removed in the crops,
produced a smaller amount of grain and straw than when
these minerals were more fully returned to the soil. They
show further that the salts of ammonia as manure were
rendered unnecessary exactly in proportion to the supply
of fixed mineral substances; for the smaller quantity of
ammonia applied to the third field gave, not a correspond-
ingly smaller crop, but on the whole a higher return than the
larger quantity of this substance on the second field which
had received mineral manure only in the first year.

The effect of mineral substances as manure is apparent
by comparing the produce of Plots II. and III. in the dif-
ferent years.

In the year 1850 Plot III. had been manured for the
third time with 300 lbs. of carbonate of potash, 200 Ibs. of
carbonate of soda, 100 lbs, of sulphate of magnesia, 200 Ibs.
of bone earth, 150 lbs. of sulphuric acid, and in the five
following years had received only salts of ammonia.

THEORETICAL AND PRACTICAL AGRICULTURE. 63

Plot IT. had only once (1844) been manured with super-
phosphate of lime and silicate of potash, and in the eleven
following years with salts of ammonia alone.

The produce of these plots from the year 1850 was the
following :—

Produce of grain and straw in Ibs.

1851 1852 1853 1854 1855

EB. Unmanured: plot:. ... 2352.4 2710 | 2457 | 1772 | 3496 | 2860
II. In 1844 received mineral sub-
stances, then up to 1855}| 5036 | 4107 | 2691 | 5808 | 3779
ammonia salts.........
III. In 1844, 1848, 1850, received
4985

mineral substances, then 4162 | 3578 | 7003 | 5074

up to 1855 ammonia salts
OR,

deat otiee as oy ss senate os ara 1000 | 1000 | 1000 | 1000 | 1000
SS APs via. hoes eden 1850 | 1630 | 1500 | 1690 | 1520
A ee ON eer ye 1800 | 1690 | 2010 | 2000 | 1770

We see from these numbers that Plot IIL, after receiving
in 1850 a large supply of mineral manure, produced in the
two following years no greater crop than Plot IL., to which
no such excess had been applied. From this absence of
any marked effect from the mineral manure, the inexpe-
rienced agriculturist might at once believe himself entitled
to conclude that the plot already contained a sufficient quan-
tity of these substances, and that, therefore, a further supply
was unnecessary, and a piece of extravagance. ‘These ex-
periments, carried out with so much perseverance, prove,
however, the unsoundness of such a conclusion. They
show that not one particle has been inefficient, but that
their action was only apparent after their distribution in
the soil had been effected. They show that these mineral
substances by themselves require a longer time to become

64 THEORETICAL AND PRACTICAL AGRICUI [URE.

active than when applied in the form of farm-yard manure,
which supplies in its organic matter a source of carbonic
acid as the natural solvent and distributor of its fixed con-
stituents. The effect of the mineral food exhibited in the
increase of produce became apparent only in the fourth
year (1853), and its continuance was still evident in the
most visible manner in the sixth year.

Whilst the ammonia salts increased the produce of the
second plot (which had seven years previously received
mineral manure) in the year 1853 one-half more than that
of the unmanured plot, the produce of the third plot, with
the same quantity of ammonia, was twice as high. In the
year 1854, its produce exceeded that of the second plot
by 381, and, in 1855, by 45 per cent.

It is hardly possible to find another cause for the differ-
ence between the two wheat fields manured with ammonia
salts, than that the one was richer than the other in the
mineral food for the wheat plant. Nothing can be more
positive than that the produce of both fields bore no pro-
portion to the quantity of ammonia applied.

As the fixed mineral constituents incorporated with the
third plot in the year 1850 must be regarded as the proxi-
mate cause of its increased produce in the years 1853 to
1855, there can be no doubt that the mineral matters (560
Ibs. superphosphate of lime, and 220 Ibs. silicate of potash),
applied in 1844 to the second plot, were equally the proxi-
mate cause of the greater return obtained from it in the
eleven following years than from the unmanured plot.

With fields under conditions so identical as the experi-
mental plots of Lawes, it cannot be supposed that the third
plot could possibly have borne a larger crop in 1858, 1854,
and 1855, than the second, had it not contained a larger
amount of active mineral matters than the latter; and had
the sum of the active mineral substances in the second plot

THEORETICAL AND PRACTICAL AGRICULTURE. 65

not exceeded that in the unmanured, the increase and con-
tinuance of the crops from this second plot would also have
been impaired.

It follows, therefore, as a natural consequence, that the
crops from the unmanured plot are also proportional to the
sum of the active mineral constituents in the soil. Had
this sum been smaller, the deficiency would have been evi-
dent in the diminution of the crops. With the increase of
these mineral matters in the second field, the crops also
increased by the aid of the salts of ammonia; and a fur-
ther quantity of these substances, applied to the third plot,
was followed by a still larger crop from that plot, not-
withstanding that it had received less ammonia than the
second plot.

It is further evident, from the above, that the crops, and
the increase in them, were dependent on the sum of the
mineral matters in the three plots, and on that portion of
this sum, which had been rendered fit for absorption by
the action of the salts of ammonia. Without the supply of
fixed mineral substances to the second and third plots in
Lawes’ experiments, they would have been, after the lapse
of a few years, precisely in the same condition as those of
Schattenmann, from which there was obtained no increase
of grain by the application of the salts of ammonia. When
by the supply of salts of ammonia, or Chili saltpetre, the
produce of corn and straw in a field is increased, the proxi-
mate cause of this increase lies in the fact, that an addt-
tional portion of the sum of the mineral substances in the
field has been thereby rendered capable of assimilation by
plants, and therefore become active. Without the presence
of such an excess of mineral matter, the salts of ammonia,
and Chili saltpetre, would not have been attended with any
effect.

A field, which, by manuring with these last-named salts,

66 THEORETICAL AND PRACTICAL AGRICULTURE.

has produced a larger crop for one or more years is thereby
impaired in fertility for future crops: for it could retain the
same degree of fertility only when the conditions of fertility
remain the same; just as it can become more fertile only
by having those conditions of fertility increased. But, in
the rich crops obtained by the use of ammonia salts and
Chili saltpetre, the farmer removes from his field in the
form of corn and straw, the mineral constituents of the soil,
and the field is consequently less rich in these substances
after the harvest than it was before.

Experience teaches, that the produce of fields in the same
district is very unequal, even though they contain the same
quantity of decaying organic matter and nitrogen. From
one meadow is obtained twice or thrice more hay than
from a similar extent of another meadow placed in the
same external conditions. An acre of clover land yields
three or four times as much clover hay as an acre of an-
other field.

The causes of this unequal productiveness, are aes
and everywhere the same.

The atmosphere conveys to two fields of equal surface a
like quantity of carbonic acid and ammonia; the more fer-
tile field, nevertheless, yields two, three, or four times more
carbon and nitrogen, in the form of hay or clover, than the
other. It is evident, that in such a case, the cause of the
increase lies in the soil, and not in the air. The more fer-
tile field has furnished to the plants two, three, or four
times more mineral food than the other: it contained a
larger absolute quantity, or a larger available proportion of
these substances.

If we take two clover fields or meadows of unequal pro-
ductiveness, in one of which there is accordingly present a
larger quantity of mineral substances than in the other; and
if we suppose that the atmosphere supplies them in one

THEORETICAL AND PRACTICAL AGRICULTURE. 67

year with two, three, or four times the amount of ammonia
they usually receive, and that their produce is thereby in-
creased,—it will be found that the increase of crop in the
two fields will be always unequal. The return from the
more fertile field will always be greater than that from the
less fertile, and this in the same unvarying proportion ; for
there has been no change in the sum of the conditions of
fertility in the soils of the two fields.

The increase in the fertility of a field by the application
of ammonia, or its salts, necessarily presupposes the pre-
sence of the conditions of this increase, and that a greater
quantity of mineral matter has in a given time become
active and capable of absorption.

In every case the produce of a field and the duration of
its fertility bear a fixed relation to the sum of the mineral
substances in the soil.

The greater or less abundance of the crop is proportional
to the rapidity of the action of the mineral matters in a
given time; that is, to that portion of their total quantity
which is annually transferred from the soil to the plant.
Hence, if a field contains so much mineral matter that,
without any supply whatever, it can yield in 100 years ex-
actly 100 average (7. e. remunerative) crops of wheat, it
may after this time possibly be still rich enough for another
kind of crop; but, in an agricultural sense, it is no longer
a wheat field.

If, by a more thorough mechanical preparation of the
ground, or by chemical means, such as Chili-saltpetre,
common salt, and salts of ammonia, the action of the avail-
able mineral food be accelerated, the field will perhaps
yield in 50 years as much grain and straw as it would have
done in 100 years without these means, and in half the time
it would be exhausted for the cultivation of wheat.

By the use of such means the total produce of the field

a

68 THEORETICAL AND PRACTICAL AGRICULTURE,

is not increased, but only the quantity obtained in a given
time.

When the agriculturist loses sight of the conditions which
determine the duration of his large crops, and relies on the
effect of his labour, and on the application of Chili-salt-
petre, salts of ammonia, and common salt, without at the
same time taking care to replace the mineral substances
removed by his crops, he is then speculating on the wealth
of his field, of the extent of which he knows nothing, and
can receive no information from others. He seizes before-
hand on the produce of his fields, which in after years
would undoubtedly have come to him; and the only
difference between him and a railway speculator is in
general this: that the punishment for his foolish deeds
inevitably overtakes him or his successors, which the specu-
lator sometimes escapes by laying on the shoulders of others.
The apparently remunerative employment of these means
on many fields may last for a long time ere the agriculturist
becomes aware of the injury he is doing himself by neglect-
ing to return the mineral substances removed by his crops;
but the longer he continues by them to obtain these large
crops, he is approaching nearer and nearer the limits at
which they must cease.

LETTER VI.

The Amount of Carbonic Acid and Ammonia in the Air—The Balance of
Organic Life—The Absorption and Assimilation of Food differs in Perennial
and in Annual Plants—The mode of Growth of Perennial, Annual, and
Meadow Plants—The quantity of Nitrogen in different Crops—Advantages
of Nitrogenous Manures to Cereals is not in consequence of the failure of
Nitrogen from Natural Sources—Organic and Nitrogenous Manures useful
in Annual Plants with small absorbent Leaf and Root-surface—Effect of
Nitrogenous Manures less marked in plants with large Leaf-surface—
Supply of Ammonia in Manure not necessary to all Plants—Green Crops
condense Ammonia from Natural Sources, and supply it in the excrement
of animals to Corn-fields—The Nitrogen of Manures is thus indirectly
obtained from the Air—The total quantity of Nitrogen from a manured
Corn-field is not greater than from an unmanured meadow, but more time
is required by the latter to collect it—Explanation of the good effect of
Nitrogenised Manures on Annual Plants with small Leaf and Root-
surface.

THE quantity of nourishment in the air, compared with
its mass, 1s very small.

If all the carbonic acid and ammonia dispersed through-
out the atmosphere were collected in one stratum around
the earth, and possessed the same density as at the surface
of the sea, the layer of carbonic acid would be a little more
than eight feet high, and that of the ammonia less than a
quarter of an inch. Both are absorbed by plants, and the
quantity of these gases in the atmosphere consequently
diminishes.

Were the whole surface of the earth a continuous mea-

dow, from each hectare (24 acres) of which 100 ewt. of hay
was yearly reaped, these meadow plants would in twenty-
one to twenty-two years exhaust the whole of the carbonic

70 THEORETICAL AND PRACTICAL AGRICULTURE.

acid in the air, and the whole living creation would at the
same time come to anend. The air would no longer sup-
port plants—that is, would no longer furnish them with an
indispensable condition of life.

We know that careful provision is made for the con-
tinuous duration of organic life. Men and animals live on
plants. All organised beings have only a passing and
comparatively short existence. In the vital processes of
animals, the food which nourishes them is transformed into
its original form; and the same change takes place with the
bodies of all animals and plants after death: their com-
bustible elements reassume the form of carbonic acid and
ammonia. Both of these substances are gaseous, and return
to the atmospheric sea, to serve once more for the forma-
tion and development of a new generation,

We thus see that the duration of organic life, in reference
to the combustible elements forming the frame of plants
and animals, is most intimately connected with the return
of these conditions. The perpetual round of changes
which the Creator has traced out for them, may, to a
limited extent, be influenced by man, but it goes on with-
out him.

Wherever food in the form of corn and other produce
of the soil abounds, there, men and animals will be found
to consume it; and these, in fulfilling the urgent natural
law of self-preservation, continuously reconvert the food
that supports them into its original elements.

The atmosphere is never at rest: even in the absence of
every breeze, it is in continual ascending and descending
motion. The food which it gives up to plants at one spot
is immediately replaced from another—from ever flowing
sources.

There is a marked difference between perennial and
annual plants as regards the absorption and assimilation of

THEORETICAL AND PRACTICAL AGRICULTURE. 71

food. For though different species may possess the same
capacity in this respect, yet the quantity necessary in a
given time for their vital purposes is very unequal. T’o
attain a maximum of growth in the shorter period of its
existence, the annual plant requires more than the biennial,
and the latter more than the perennial. :

Everything that tends to promote the growth of plants
in general, exerts the same favourable influence on perennial
plants as on biennials and annuals, but with this distinc-
tion, that the development of the former is not in the same
degree dependent on accidental and passing states of wea-
ther. If the weather is unfavourable, the growth of the
perennial is only retarded for a time: they can await a
favourable change. Whilst thus waiting their increase is
only for the time being arrested, but the annual plants
reach the limit of their existence and die.

In the first periods of the growth of perennial plants,
the most powerful efforts of their vital energy are chiefly
directed to the formation of roots. The atmospheric food
received by the leaves is destined for the prolongation and
ramification of these underground organs of absorption.
This fact is most distinctly perceptible in young trees,
which appear to grow so slowly in the first periods of their
existence, and afterwards so rapidly. When the roots have
acquired a certain compass, their stem or stalk then
increases in strength much more rapidly than at first, and
the branches, shoots, and leaves, augment in number.

In the growth of annual plants, the food is expended in
two directions at the same time, viz., for the formation of
the shoots, as well as of the leaves and roots; they are,
therefore, in reference to the equal supply and the proper
proportion of their food, much more dependent than peren-
nial plants on the condition of the soil, and on weather.
The development of all parts of the annual plant must

72 THEORETICAL AND PRACTICAL AGRICULTURE.

take place within a certain definite, relatively short period
of time, and its growth can only be complete when the
external conditions are equally favourable with those of
the soil. |

The formation of underground suckers appears to be of
the greatest importance to vegetation in the case of the
perennial grass and meadow plants, because by them vege-
tation is maintained. They appear mostly in cases where
scarcity of food or external disturbing circumstances would
endanger annual plants. Only the smallest portion of the
plants on a thickly-covered plot of grass produces stems ;
the greater part develops only tufts of leaves; and a num-
ber only underground suckers. A landscape essentially
derives its character from perennial plants, which every-
where take possession of the ground when not prevented
by man. Cleared forest-land produces immediately in the
succeeding year plants, many of which (as, for example, the
raspberry) flower and bear fruit in the same year, and
therefore could not have grown from seed. By continu-
ously putting forth underground suckers, plants are kept
for a number of years at a low state of growth, till ulti-
mately the conditions for their complete development
recur.

The duration of vegetation on our meadows depends
on this circumstance. The certainty of their produce
under varying conditions of soil and weather, arises from
the great number of plants, which are able to maintain
themselves at this low stage of development.

Whilst one species of plants grows, flowers, and bears
seed above ground, a second and third collects below it the
conditions for a similar future growth. The one seems to
disappear, in making room for a second or third, until the
conditions for its own growth again recur. By manuring
with ashes we cause clover plants to shoot out from the

THEORETICAL AND PRACTICAL AGRICULTURE. 73

green sward. An abundant crop of French rye-grass
showed itself when superphosphate of lime was applied,
but not a straw of this grass was to be seen where no
superphosphate fell.

A wonderful provision of nature ensures, by this
sequence and change, the continued existence of plants,
which clothe the fields with perennial green. The agri-
culturist, in adopting the rotation of crops in the cultiva-
tion of the annual plants which supply the food of man
and animals, but follows in this operation a higher law.

The circle from which a perennial plant extracts its food
enlarges from year to year; if its roots find but little in
one spot, its wants are supplied from another which is
richer. Whilst the roots of annual plants die every year,
perennial plants preserve theirs in a state of readiness to
absorb food at every favourable opportunity. Many retain
their stalks or stems, in which are stored up, for the future
necessities of leaves and buds, the unconsumed portion of
their food. Hence, perennial plants grow with luxuriance
on comparatively poor ground, which will not yield annual
plants without a supply of food from the hand of man.

Annual plants cannot follow each other continuously on
the same soil without exhausting it; hence, in the rotation
of crops, perennial plants come most advantageously after
the annual, and wie versd.

The nearer an annual plant approaches in its comport-
ment to a perennial, the more independent is it of any
supply of atmospheric food. So long as a plant puts forth
fresh leaves, it exists and maintains its power of absorbing
carbonic acid and ammonia from the atmosphere; and,
during the continuance of this power, there is so much the
less necessity for a supply of these substances from the
soil.

A pea plant which pushes out fresh leaves and blossoms,

ie

74. THEORETICAL AND PRACTICAL AGRICULTURE.

at the same time that its seeds are ripening, receives more
combustible elements from the atmosphere, than a corn
plant, whose leaves and green stem fade after the appear-
ance of the flower, and with the ripening of the seeds,
and consequently lose their power to absorb atmospheric
food.

Hence we can understand why organic substances which,
in decaying, supply to the roots carbonic acid and ammo-
nia, when applied at the proper time cause in one plant an
increase of vegetable matter, and in the amount of seed,
whilst the produce of another is scarcely increased by
them.

From an equal surface of land we obtain in different cul-
tivated plants a very unequal amount of blood and flesh
constituents, or nitrogen. If we designate by the number
100 the quantity of nitrogen which is yielded by a field of
rye inthe form of grain and straw, we shall obtain from
the same field—

In Oats. : * ‘ 114
Wheat . 5 5 : : ‘ 118
Peas... i F . " F 270
Clover . ‘ : i ; . 390
Turnips. : ; : : : 470

Accordingly peas, beans, and green crops in cultivation,
yield more nitrogen than the cereals. Peas and beans give
more than double, clover and turnips three or four times
more flesh and blood constituents than wheat. Clover and
turnips can yield on many fields this higher produce with-
out receiving any nitrogen in manure. In the case of
clover, the yield can be still further augmented by the
application of ashes, and in that of turnips by superphos-
phate of lime.

In cultivation, nitrogenous manures prove particularly
useful for cereals, though the growth of clover and root-

THEORETICAL AND PRACTICAL AGRICULTURE. 75

plants on many fields is also greatly promoted by them.
In general, the luxuriant growth of green crops on fields
which have received no nitrogenous manure shows, that the
utility or necessity of these manures for cereals does not
arise from a deficiency in the supply of nitrogen from
natural sources, and cannot be explained by a supposed
failure of this supply. The column of air floating above a
clover and corn field offers to both plants the same amount
of carbonic acid and ammonia, yet from the same soil from
which the agriculturist has received a very poor return of
nitrogen in the form of grain and straw, he obtains three
or four times the quantity of nitrogenous constituents in a
crop of a fodder plant. The same source of nitrogen was
open to both plants; there could, therefore, have been no
deficient supply to the corn plant, since the clover drew
from it its three and fourfold quantity. It is quite certain
that a soil, from which a poor crop of corn has been
reaped, will not be made to yield a greater quantity, even
by the most abundant application of ammonia.

The failure of the corn crop must therefore be owing to
other circumstances, and the proximate causes must be
sought for in the condition of the soil.

On the other hand, it cannot be doubted, that two fields
containing equal quantities of the fixed food of plants, are
nevertheless unequally productive in cereals, if in one of
them there exist more carbonaceous and nitrogenised organic
matter than in the other. The field which is richer in
organic matter produces a higher crop of corn and straw.
It is further certain that, if an equal quantity of the fixed
constituents of food has been supplied in manure to two
fields, but one of them has at the same time received in
addition in organic matters a store of carbonic acid and
ammonia, in general the latter will produce a larger crop
of corn than the other.

76 THEORETICAL AND PRACTICAL AGRICULTURE.

This increase of produce under these circumstances (in
which the soil is supposed to be rich enough in mineral
food and in carbonaceous and nitrogenous organic matter)
takes place in the case of cereals as well as of other annual
plants, with a scanty supply of leaves and limited ramifi-
cation of roots; and the reason of the utility, in such cases,
of organic and nitrogenised substances, is very evident. It
lies manifestly in this, that the amount of nitrogenised
products, which can be obtained from a given surface of
such land, is in fixed proportion to the extent of leaf sur-
face, or in general terms, to the organs of absorption, and
to the t&éme in which these organs are in a state of
activity. ;

If one plant possesses twice the extent of surface of
leaves which exists in another, it will, during the same
period of vegetation, extract double the quantity of nitro-
gen from the air.

Of two plants with equal extent of surface of leaves, and
under similar circumstances, but with unequal periods of
vegetation, one will yield a larger crop than the other, if
with the same supply of food it has longer time for its
absorption. By manuring his fields with nitrogenous sub-
stances, the agriculturist exercises an immediate influence
on the produce; and the effect of these manures, through
the nitrogen they contain, is in inverse proportion to the
absorbing leaf and root-surface, and to the period of vegeta-
tion of the crop.

The effect of nitrogenous manures is less marked in
plants with a large surface of leaves (as in peas, turnips), or
which have a longer period of vegetation (as in meadow
plants, clover) than in culmiferous plants. Ammonia is
necessary as food to all plants, but a supply of it in
manure is, in the agricultural sense, not useful to all culti-
vated plants.

THEORETICAL AND PRACTICAL AGRICULTURE. i?

Experience has taught the agriculturist to make a dis-
tinction in this respect. As a rule, he does not manure his
clover field with nitrogenous matters, because the crop of
clover is generally not thereby visibly increased, or only
very slightly ; whilst he reaps a decided advantage in the
increase of his produce by applying these matters to his
corn fields.

The agriculturist therefore makes use of green crops as a
means of increasing the productiveness of his corn fields.

Green crops, which thrive without nitrogenous manures,
collect from the soil and condense from the atmosphere, in
the form of blood and flesh constituents, the ammonia sup-
plied from these sources. When the agriculturist feeds his
cattle, sheep, and horses with these green crops, he obtains
in their solid and liquid excrements the nitrogen of the
fodder in the form of ammonia and highly nitrogenised
products, and thereby a supply of manure for his corn
fields.

The ultimate source of the nitrogen with which the
agriculturist manures his corn fields is invariably the air.
Hach year he carries away from his land a certain quantity
of nitrogen in the form of fattened animals, corn, cheese, or
milk: but his trading capital of nitrogen is maintained and
increased, if he knows how to replace the deficiency by the
cultivation of green crops in proper proportions.

In the temperate zones, it is usually on the annual plants
that man depends for his food; and the problem which the
agriculturist has to solve, is to obtain from his land in the
form of annual plants as much food for man, as perennial
plants furnish to animals from the same extent of surface.
Nature takes care of animals which cannot take care of
themselves; whilst for the purpose of ensurmg the means
of his subsistence, man has been endowed with the power
of making the laws of nature minister to his wants.

78 THEORETICAL AND PRACTICAL AGRICULTURE.

The best corn field, which has been manured, produces
altogether no more blood and flesh constituents than a gocd
meadow, which has received no nitrogenous manure. But
the corn field without manure would have yielded a smaller
amount of these constituents than the meadow.

Whatever deficiency there is in the quantity of atmo-
spheric food, taken up by corn plants within a given time
from natural sources, to produce a maximum of corn and
straw; whatever amount of food the scanty supply of leaves
has not the power of absorbing from the air during the short
period of their existence, that portion the agriculturist sup-
plies through the roots.

The agriculturist thus supplements by manures the dif-
ference between the amount of atmospheric food taken up
in eight months by meadow plants, and that obtained by
cultivated plants from the air during their more limited
period of vegetation of four to six months; and he thereby
ensures to corn plants, during their shorter existence, as
much nitrogen for assimilation as is furnished to meadow
plants from natural sources.

Hence the explanation which can be offered of the effect
of nitrogenised manures and their advantages in certain cases
is, that the agriculturist furnishes to certain plants, having a
scanty supply of leaves and roots and a short existence, in
quantity as manure, the nitrogen which they have not time
to absorb from natural sources.

But the agriculturist does not always apply the nitrogen
with which he augments his crops in the form of the
ammonia of rotting excrements of man and animals. He
also employs frequently for this purpose other nitrogenous
substances, as horn, dried blood, fresh bones, rape-dust, &c.

We know that these substances, as well as all nitrogenous
matters derived from man and animals, by degrees decay in
the soil, and their nitrogen is gradually transformed into

THEORETICAL AND PRACTICAL AGRICULTURE. 79

nitric acid and ammonia, and that the latter is absorbed and
retained by the soil.

Tn all cases in which ammonia as such produces favourable
results on crops, these substances, so far as regards the
nitrogen they contain, also act in the same manner. But
their effect 1s more slowly produced, because they require,
according to the greater or less facility with which they are
decomposed in the soil, a certain time for the transformation
of their nitrogen into ammonia. Dried blood and flesh, as
well as the nitrogenous constituents of rape-cake, act more
quickly than the gelatine of bones, and the latter more
quickly than horn.

LETTER VIL

Salts of Ammonia increase the number of Roots and Leaves in the first period
of the Growth of Plants; hence the superior action of these salts in Spring
—Circumstances which modify the production of Leaves, Flowers, and Roots
—Circumstances under which Nitrogenous and Concentrated Manures are
useful—Causes of the failure of plants continuously grown on the same Soil
—Food of plants when too concentrated often exerts a deleterious Chemical
action—Provision in the Soil to prevent this action—Properties of Soils
altered in cultivation by the removal of Mineral Matters from them, and by
the increase of Organic Matters in them—The increase of Organic Matter
frequently a cause of Disease—Finger and Toe disease; its cure—Excess
of soluble Silica and of hurtful Organic Matter in soils removed by Lime—
Noxious Organic Matters arising from the continuous growth of Perennial
Plants on Meadows removed by Irrigation.

THE experiments of Kuhlmann, Schattenmann, and Lawes,
agree in showing, that the salts of ammonia exert a most
favourable influence on the evolution of straw and leaves ;
and if this influence extends in like manner to the under-
ground organs, the roots, then it ought to follow that the
action of ammonia promotes the development of those
organs destined for the absorption of food, and that these
salts applied at the proper time increase the number of the
leaves and roots.

This circumstance explains the favourable action exer-
cised in spring by ammoniacal manures, whilst in summer
their influence under otherwise similar circumstances is
trifling.

If the plant, in fact, has produced during the first period
of its growth a sufficient number of leaves and roots, an
additional supply of ammonia can be of no great use to its

THEORETICAL AND PRACTICAL AGRICULTURE. 81

further development, where the other constituents of food
in the soil are not deficient; for the leaves can now receive
from the air the nitrogenous food necessary to the formation
of seeds. In summer there is more watery vapour in the
air than in the colder spring; and as the quantity of ammonia
in the air, according to the observations of all experimenters,
increases with the temperature and moisture, plants must
necessarily find more ammonia in the air in summer than in
spring. We may as a rule hold, that in the colder seasons
of the year, plants are more dependent on a supply of
ammonia from the soil, than in the warmer; or in other
words, that the employment of nitrogenous manures in
spring is most advantageous to plants.

In England and Scotland it is the result of general ex-
perience, that the earthy phosphates are not always sufii-
cient for a good and certain crop of turnips. When sown
in May they require the addition of a nitrogenous manure,
whilst, if this take place in the middle of June, they thrive
generally as well with phosphates alone, as when combined
with ammonia.

We can hence tolerably well define the cases in which
ammonia is hurtful; for whilst nitrogenous manures pro-
mote the growth of the leafy cabbage, they impede that of
the roots of turnips. The latter plant is frequently ob-
served to shoot out only stem and leaves when growing on
spots upon which manure heaps have lain. Mangold-wurzel
in a similar case produces the largest roots. The flowering
time of these plants is delayed by this manure.

To produce flower and seeds, it appears to be a necessary
condition, in many cases, that the activity of the leaves
and roots should reach a certain limit,—a period of rest.
It is only from this period that the vegetative activity
_ appears to take a decidedly new direction, and that the
sap, when no longer required for the production of new

%

82 THEORETICAL AND PRACTICAL AGRICULTURE.

leaves and roots, is applied to the formation of flower and
seed

With many plants want of rain, and of the consequent
supply of food, limits the formation of leaves, and pro-
motes the production of flowers. Dry and cool weather
hastens the formation of seeds. In warm and moist cli-
mates, the cereals when sown in summer bear little or no
seed ; and root crops flower and bear seed more readily on
a soil poor in ammonia, than on one rich in this substance.

In the employment of nitrogenous manure, the agricul-
turist must consequently have distinctly before him the
object which he wishes to attain. He must act with plants
as with animals. When he wishes to fatten the latter, and
at the same time to preserve their health, he gives them
daily no more food than they can digest.

Manures must always be of such a nature as to furnish
plants with their suitable food at each period of their
growth. Plants which have a longer period of vegetation,
require consequently no supply, or, at least, a much smaller
one of nitrogenous manures than those whose period of ex-
istence is short. For such as possess the shortest period
of vegetation, and which grow rapidly and with vigour, the
concentrated manures are preferable to those which give
up their active constituents only slowly. In dry localities,
winter wheat thrives after clover without further manuring;
whilst, as a rule, the application of Peruvian guano or
Chili-saltpetre (top-dressing) is most beneficial to wheat
sown in spring.

The continuous edie of the same plant on the
same field, does not necessarily unfit this field for its pro-
duction, if it is amply provided with the chemical condi-
tions for the growth of the plant, and possesses physical
properties of a right kind. If after the third or fourth
year, the plant no longer thrives on such a field, the reason

THEORETICAL AND PRACTICAL AGRICULTURE. 83

manifestly does not lie in any deficiency of its vital condi-
tions (for we have assumed that these are present), but in
the accumulation of causes which injure its healthy growth.

The food of plants consists of chemical compounds,
which, in virtue of their chemical properties, produce cer-
tain effects on the substance of the cells and the most deli-
cate portions of the frame of the leaves and roots, by which
plants appropriate their food. Their chemical action in-
creases with their quantity; and if presented to plants be-
yond certain limits, they sicken and ultimately die.

In air in which free ammonia is present in excess, even
though it be to only a most minute extent, many plants
die as if struck with a poisonous blast. Carbonic acid acts
in a similar way, though in a less degree; and weak solu-
tions of free alkalies or alkaline earths and their salts in a
soil produce the same effect on other plants.

In nature we find a wonderful provision exists in the
chemical and physical properties inherent in the soil, for
completely obviating the chemical action of the nutritive
matters on the absorbent rootlets. Free ammonia, the free
alkalies, and alkaline earths, are fixed by the soil, and with
their loss of solubility they also lose those chemical pro-
perties which are hurtful to plants. Plants can then select
what is necessary to their existence, without any hindrance
from extraneous influences which may endanger their pro-
per growth.

It is evident that the soil must possess such a neutral
chemical character as the most important condition of the
healthy structure and functions of the roots. The different
species of plants require, however, special conditions for
the growth of each. One species requires the constituents
of fresh spring water; another flourishes only in bogs;
others in carbonaceous and sour soils; others, again, only
in ground which abounds in alkaline earths.

84 THEORETICAL AND PRACTICAL AGRICULTURE.

By cultivation the character of the soil is modified, not
only by the removal in crops of a portion of its active in-
gredients, but also by the addition to it, by means of many
plants, of a greater amount of carbon and nitrogen sub-
stances, in the form of the remains of roots. The enrich-
ment of the soil in organic matter appears to be a cause of
disease and death to many plants. Clover and many of
the turnip tribe will no longer grow on such a soil, and
several species of grass quickly disappear from it.

It has been frequently found in England that turnips,
when grown on the same field at too short intervals, become
subject to a peculiar disease, which manifests itself in an
unusual development of the roots. Instead of a round,
fleshy head, weighing several pounds, from which filament-
ous roots spread out into the ground, the tap-root splits into
a great number of hard, woody, stem-like roots of the thick-
ness of a finger (finger and toe disease). This disease, which
is owing to the peculiar character of the ground, is removed
by a large dose of quick lime. It is certain, however, that
the lime does not act in this case, because there was pre-
viously a deficiency of it in the soil, for a supply of it to
the field at seed time, like other manures, produces no
effect, for the latter is apparent only after one or two years.
To produce a favourable change in the quality of the field,
the lime must manifestly penetrate to a certain depth, and
this requires a considerable time. By the simple applica-
tion of superphosphate of lime, to the complete exclusion
of organic manures, Lawes succeeded in raising nine suc-
cessive crops of turnips on the same land, and in the ninth
year obtained 187 cwt. of roots per acre.

Rain water, in slowly filtering through a soil rich in
organic matter, extracts a substance which communicates a
brown colour, and at times an acid reaction to the water.
An addition of burnt lime to this soil destroys the solubility

THEORETICAL AND PRACTICAL AGRICULTURE. 85

of the organic matter in water, and its power of diffusion
in the soil. The lime decomposes the organic substances,
and by its presence converts the process of putrefaction,
which is hurtful to plants, into one of decay which is advan-
tageous to them.

The presence of organic matter in a soil rich in silicates,
enables water in percolating through the soil to dissolve a
much larger quantity of hydrated silicic acid than is con-
ducive, in many plants, to the process of absorption taking
place in the roots. Lime destroys this property, and, by
_ its direct action on the silicate, potash is ultimately set free,

and rendered fit for distribution in the soil. Sainfoin con-
tinues to flourish on fields rich in lime. It is certain that
the presence of the lime in such a soil is not advantageous to
this plant, because it requires more lime for its vital pur-
poses than other plants which flourish luxuriantly on land
much poorer in lime; but the cause for the necessity of this
excess of lime must be sought for in the fact, that it destroys
certain injurious matters which gradually accumulate by
the contintous growth of this plant on the same soil.

As a matter of course we understand, that, in a number
of cases in which the same plant will no longer grow on
the same soil, the cause just indicated is not alone in opera-
tion, but deficiency of food generally, or in the proper pro-
portions, must be regarded as the proximate cause of the fail-
ure. The necessity for taking into consideration so many
causes which impede or promote the growth of plants,
makes the practice of agriculture one of the most difficult
of pursuits.

In fields bearing perennial plants, with roots which pene-
trate to no great depth, similar injurious matters gradually
collect, which are hurtful to the growth of future genera-
‘tions of plants. The irrigation of meadows appears. to
accomplish the important object among others of removing

86 THEORETICAL AND PRACTICAL AGRICULTURE.

these injurious matters by the oxygen and by the carbonic
acid dissolved in the water, which penetrates the ground,
and brings it into a condition similar to that produced by
careful ploughing. An analysis of the water flowing from
the meadow would probably show that it removes as much
mineral matter and ammonia as it brings toit. We do not,
of course, here speak of. meadows to which liquid manure
has been applied, or which have been irrigated with rich
sewerage water from towns; for in these cases two causes
are in operation to augment the produce, one of which (a
supply of mineral food and ammonia) is almost excluded
in the case of spring and river water.

LETTER VIL

The food of Land Plants is not absorbed by the roots from Solution, but from
the Soil directly in contact with them—Hence the necessity for a uniform
distribution of the food of plants in the soil, and for the great Ramification
of their Roots—A field with much mineral food may be comparatively
unproductive if it is not thoroughly mixed with the Soil—The roots of a
crop diminish the mineral food in those portions of the soil in contact with
them—Fertility is restored to those portions by ploughing and other
mechanical means, which mix the soil and allow the roots to ramify freely
—Reason of the value of Green Manures—Estimation of amount of mine-
ral food in the soil to produce different Remunerative Crops—Law of
Exhaustion in soils for different crops—Action of organic remains in the
soil on the mineral constituents—Progress of diminution in Grain and Straw
of cultivated crops, when the Ash Constituents are not restored to the soil,
and when those of the straw alone are returned—Relation between the pro-
duction of Leaves and of Grain—Relative proportions of mineral food
required for Grain and for Root or Leaf-producing crops—The increase of
Organic matter and Nitrogen in the soil by Green Crops, without the
addition of mineral food, augments the produce of grain, but hastens the
period of Exhaustion of the soil—Progress of the exhaustion of a soil by
the cultivation of shallow and of deep rooting plants—The manner in which
the Subsoil contributes to the prolongation of the fertility of land—
Importance of the formation of large roots after germination—Exhausted
fields in an agricultural sense—Fertility restored by manures—The nature
of Manures—The part played by the Organic and Inorganic Matter of
Manures—Farm-yard Manure.

THE culmiferous, turnip, and tuberous plants which the
agriculturist cultivates, comport themselves in a most pecu-
liar manner in the absorption of their mineral food. Whilst
sea-plants receive their whole supply of these substances in
a state of solution from the surrounding medium, the water
which percolates through cultivated soils, brings to the

88 THEORETICAL AND PRACTICAL AGRICULTURE.

roots of land plants none of the three most important and
most essential elements of food, viz., phosphoric acid, pot-
~ ash, and ammonia. Water alone withdraws from the soil
none of these substances; their passing into the organism
of plants must therefore be directly effected by the organs
of absorption inthe ground, with the co-operation of water.
The roots extract these substances from those portions of
the soil, penetrated with water, which are in direct contact
with their absorbent surfaces; and such portions of soil
must contain the whole quantity necessary for the complete
development of the plant, since the roots can receive none
of them, except from the particles of earth with which they
are directly in contact.

If the food of plants in the soil cannot move towards the
roots, it is evident that the roots must spread about to look
for food.

Plants cannot obtain from the soil more food than it
contains. Further, its fertility is not to be measured by
the whole quantity present in it, but only by that portion
of the whole quantity which exists in the smallest particles
of the soil. For it is only with such portions that the root-
lets can come into close contact.

A piece of bone weighing about 80,000 milligrammes
(one ounce) in a cubic foot of earth, produces no marked
effect on its fertility. But if these 30,000 milligrammes of
phosphate of lime be uniformly distributed throughout the
earth, it will suffice for the nourishment of 120 wheat
plants. Ten thousand milligrammes of food, having a sur-
face extent of 100 square millimétres, are within the same
given time not more effective than ten milligrammes having
the same surface extent. Of two fields with the same
amount of food, one may be very fertile, and the other
equally unfruitful, if the food is more uniformly distributed
throughout the former than the latter.

THEORETICAL AND PRACTICAL AGRICULTURE. 89

The common plough breaks and turns up the soil with-
out mixing it; it only displaces, to a certain extent, the
spots on which plants have already grown. But the spade
breaks, turns, and mixes it thoroughly.

A potato, turnip, or wheat plant cannot thrive on the
spot in which the same kind of plant has grown in the pre-
ceding year, if the portions of soil with which the rootlets
were in contact, contain no more, or only an insufficient
residue of food. The roots of the succeeding plants find in
all these spots either no food or only a deficient supply.
Every other spot contains more.

As the smallest portions of food cannot of themselves
leave the spot in which they are held firmly fixed by the
soil, we can understand what immense influence must be
exerted on its fertility by its careful mechanical division
and thorough intermixture.

This is the greatest of all the difficulties which the agri-
culturist has to overcome.

If a field is to produce a crop, corresponding to the full
amount of food present in it, the first and most important
condition for its accomplishment is, that its physical state
be such as to permit even the finest rootlets to reach the
spots where the food is to be found. The extension of the
roots in every direction must not be obstructed by the
cohesion of the soil. Plants with thin delicate roots cannot
grow on a tenacious heavy soil, even with abundance of
mineral food. These facts explain in a very simple manner,
one of the many favourable effects of green manures on
such soils, and enable us to understand the reasons of the
preference given in many cases, by agriculturists, to fresh
over rotten farm-yard manure. The mechanical condition —
of the ground is, in fact, remarkably altered by the plough-
ing in of plants and their remains. A tenacious soil loses |
thereby its cohesion ; it becomes brittle, and more readily

90 THEORETICAL AND PRACTICAL AGRICULTURE.

pulverized than by the most careful ploughing; and, in a
sandy soil, a certain coherence is introduced among its
shifting particles. Each stem of the green manure plants
ploughed in opens up by its decay a road by which the
delicate rootlets of the wheat plant ramify in all directions
to seek their food. With the exception of their combus-
tible elements, the ground receives from the green manure
plants nothing which it did not previously contain; and
these of themselves would have no effect on the increase of
the crop, without the presence in the soil of the necessary
mineral food.

None of the three most important constituents of food
exists, by itself, in a soluble form in the ground, and none
of the means employed by the agriculturist to make them
available to his plants, deprives the soil of its power of
retaining them; or, if dissolved, of withdrawing them from
this solution. The principal end gained by the means he
employs is only an uniform distribution of the food
throughout the soil, so as to put it within the reach of the
roots of his plants.

A 24 acre field (= 1 million square decimétres) of good
wheat soil produces an average crop of 2000 kilo. ( = 4411
Ibs.) of grain, and 5000 kilo. ( = 11,028 Ibs.) of straw; the
two contain together 250 kilo. ( = 551 Ibs.) of mineral sub-
stances. Each square decimétre (= 10,000 square milli-
métres or 15°5 square inches) of this field yields 250 milli-
grammes ( = 3°85 grains) of ash constituents to the plants
growing upon it. Hach square millimétre (= °00155
square inch), from the surface downwards, must contain a
quantity of food corresponding to the wants of each indi-
vidual rootlet. If the food is wanting in any one particular
particle of the soil, then this portion cannot contribute to
the nourishment of the plant. The amount of food im each
portion of a transverse section of ground, tn each square mulli-

THEORETICAL AND PRACTICAL AGRICULTURE. 91

metre from the surface downwards, ts the measure of us capacity
for production. Each rootlet absorbs, according to its dia-
meter, the food with which it comes in contact on its way
downwards.

If we suppose that the sectional area of the roots of the
whole wheat plants which grow on a square decimétre
amounts to 100 square millimetres, or that upon the same
surface there exists a wheat plant with two or three stems,
and with a hundred roots each of a square millimétre sec-
tional area, then must each of these rootlets receive 24
milligrammes of mineral food in order to supply the plant
with 250 milligrammes, Hach of the 10,000 square milli-
métres (= one square decimétre), from the surface down-
wards must contain these 24 milligrammes; which would
give a total quantity of 25,000 milligrammes (= 25
grammes = 386 grains) to the square decimétre, calculated
to a depth of 10 inches; or 25,000 kilo. (244 tons), to the
hectare (24 acres), 2. e., somewhat more than 4 per cent. of
the whole soil.

A hectare which, from the surface downwards, contains
no more than 250 kilo. = 550 lbs. of mineral matter (of
which 50 kilo. = 110 lbs. are potash, and 25 kilo. = 55 Ibs.
are phosphoric acid) would, according to this calculation,
be completely unsuitable for wheat; for even though each
wheat plant possessed, instead of one hundred, one thou-
sand roots, each of the thickness of a hyacinth root, it
would nevertheless not be able to receive by these more
than a tenth part of its wants from the soil.

According to our assumption, which probably barely
reaches the full amount really present, a hectare must con-
tain, from the surface downwards, in order to yield an
average crop of wheat, at least 5000 kilo. (= 11,000 lbs.)
of potash and 2500 kilo. (= 5500 Ibs.) phosphoric acid.*

* If the mineral food, so very small in proportion to the whole mass of

92 THEORETICAL AND PRACTICAL AGRICULTURE.

If an average wheat crop of 2000 kilo. (= 4400 lbs.) of
grain and 5000 kilo. of straw, has removed one per cent. of
the mineral food from the soil, the latter remains still pro-
ductive for new wheat crops in the following years; but the
amount of produce diminishes.

If the soil has by mechanical means been most carefully
mixed, the wheat plants of the second year on the same
field will find at each spot one per cent. less food, and the
produce in corn and straw must in the same proportion be
smaller. Under similar conditions of weather, tempera-
ture, and fall of rain, only 1980 kilo. (= 4856 Ibs.) of
grain, and 4950 kilo. (= 10,890 lbs.) of straw, will be
reaped in the second year; and in each following year the
crop must fall off in a fixed ratio.

If the crop of wheat removed in the first year 250 kilo.
(= 550 lbs.) of mineral constituents, and a hectare (23 acres)
of soil to the depth of 12 inches, contained one hundred
times this quantity (25,000 kilo., or 243 tons), there will re-
main in the soil at the end of thirty years of cultivation,
18,492 kilo. (= 18 tons) of food.

Whatever then may have been the variations in the
amount of produce from this field, in the intervening years
caused by different conditions of weather, it is evident, that
if there has been no replacement of the mineral matters re-
moved, there can be obtained in the thirty-first year, under
the most favourable circumstances, only 123 = 0°74, or some-
what less than # of an average crop.

soil (2 grains in a cubic inch), were present in chemical combination with it,
it is impossible to form an idea how it could be distributed in this state every-.
where in the soil, so as to be reached by the roots. The comportment of
soils of the most different kinds towards solutions of these elements, shows
that they are present and fixed in a way somewhat similar to colouring mat-
ter in dyed stuffs, or in charcoal which has been used to decolorise a fluid;
in these cases a very small quantity in weight is sufficient to cover an extra-
ordinary extent of surface.

THEORETICAL AND PRACTICAL AGRICULTURE. 93

If these # of an average crop do not yield to the agri-
culturist a sufficient excess of income over expenditure, if
they merely cover his expenses, then the crop is no longer
remunerative. He considers the field to be now exhausted
for wheat crops, although it still contains seventy-four times
more food than an average crop yearly requires. The
effect of the total quantity of mineral food in the soil has
been, that in the first year each root found in those portions
of the soil with which it came in contact, the requisite
quantity of these substances for its complete development;
and the result of the subsequent continuous crops has been,
that in the thirty-first year only ? of this quantity is found
in these portions.

A field exhausted for wheat cultivation, will produce
remunerative crops of rye.

An average crop of rye (= 1600 kilo., or 3520 Ibs. of
grain, and 3800 kilo., or 8360 lbs. of straw) extracts from
the ground per hectare only 180 kilo. (= 396 Ibs.) of
mineral matter. Under similar circumstances, one rye
plant takes up only 180 milligrammes (= 2°77 grains).

If a soil must contain 25,000 kilo. of mineral matter, in
order to produce an average crop of wheat, a soil in which
there are only 18,000 kilo. of the same substances, is rich
enough for an average crop of rye, and will yield a number
of such crops which shall be remunerative.

According to our calculation a field which is exhausted
for the cultivation of wheat, still contains 18,492 kilo. of
mineral matter, which in their properties are identical with
those required for rye.

If we now inquire after how many years of continuous
rye cultivation will the average crop fall to one of ? the
- amount, we find,—assuming that this amount is no longer
remunerative,—that after 28 remunerative crops, the field
will be exhausted for the cultivation of rye. The mineral]

94 THEORETICAL AND PRACTICAL AGRICULTURE.

matters still remaining in the ground amount, however, to
13,869 kilo. (= 134 tons.)

A field on which rye can no longer be cultivated with
profit, is not necessarily unsuitable for oats.

An average crop of oats (2000 kilo. of grain and 3000
kilo. of straw per hectare), withdraws from the soil 310
kilo. (= 682 Ibs.) of mineral matter, being 60 kilo. (= 182
Ibs.) more than a wheat crop, and 130 kilo. (= 286 lbs.)
more than a rye crop.

If the absorbent root surface of the oats were the same as
that of rye, then oats following rye would not be a remu-
nerative crop; for a soil which furnishes 810 kilo. out of a
stock of 18,869 kilo. for a crop of oats, loses thereby 2°28
per cent. of its amount of mineral constituents; whilst by
our calculation the roots of the rye extract only one per
cent. This can only happen if the root surface of the oats
exceeds that of the rye 2°23 times.

According to the above, the oat crops will exhaust the
soil most rapidly. After 12% years the return of produce
must sink to % of its original amount.

None of all the causes which may diminish or increase
the amount of a crop, has any influence on this law of
exhaustion of the soil by cultivation. When the sum of
the food has reached a certain point of diminution, then
the soil ceases to be productive, in an agricultural sense, for
a cultivated plant. If by incorporating with it atmospheric
food, organic materials and salts of ammonia, the produce
has been augmented for a number of years, the state of
exhaustion will then occur sooner. On the other hand,
any obstacle to the free absorption of food diminishes the
amount of produce, and the limits of exhaustion are conse-
quently reached at a /ater period.

For each cultivated plant, there exists a similar law.

This state of exhaustion inevitably happens, even when there

THEORETICAL AND PRACTICAL AGRICULTURE. 95

has been withdrawn from the soil by a course of crops only one
of all the different mineral substances necessary for the nourish-
ment of plants; for the one which is awanting, or exists in
deficient quantity, renders all the others inefficient, or deprives
them of their activity.

With each crop, each plant, or portion of a plant, taken
away from a field, the soil loses a portion of the conditions
of its fertility; that is, it loses the power of again producing
this crop, plant, or portion of a plant, after the expiration
of a number of years of cultivation. A thousand grains of
corn require from the soil a thousand times as much phos-
phoric acid as one grain; and a thousand straws a thousand
times as much silicic acid as one straw; if, therefore, there
is a deficiency of a thousandth part of the phosphoric or
silicic acid in the soil, then the thousandth grain and straw
wiil not be formed. A single corn straw removed from a
corn field, makes this field bear one corn straw less.

If it is true that the mineral constituents of the culmi-
ferous plants are indispensable for their growth, and must
be supplied by the soil, if the plants are to flourish ; if it is
true that among these mineral matters, potash, phosphoric
acid, and silicic acid, are not conveyed to the roots in a state
of solution, then it necessarily follows that a hectare ( 24
acres), containing 25,000 kilo. (= 244 tons) of the constitu-
ents of the ashes of wheat, uniformly distributed through
it, and in a state quite fit for assimilation by the roots, can
to a certain point yield a series of remunerative crops of
different species of straw plants, without any replacement
of the minerals removed in the grain and straw, if a uniform
state of mixture of the soil has been maintained by careful
ploughing and other suitable means. The succession of
such crops is determined by this, viz. that the plant culti-
vated the second year shall take away from the soil less
than that of the first; or that it contains a greater number

96 THEORETICAL AND PRACTICAL AGRICULTURE.

of roots, or, in general, a greater absorbent root surface
than the first. From the average crop of the first year,
there would be a diminution of produce from year to year.

The agriculturist, to whom uniform average crops are
exceptions, and varying returns caused by changing states
of weather is the rule, would most probably not have noticed
this constant diminution, not even though his field had in
reality possessed such favourable chemical and physical
conditions as to have enabled him to cultivate on it for
seventy years successive crops of wheat, rye, and oats,
without replacing any of the mineral matters withdrawn
from it.

In‘ favourable years, good crops approaching nearly to
an average one, would have alternated with bad crops in
other years, but the proportion of unfavourable to favour-
able crops would have constantly increased.

The greater number of Kuropean fields under cultivation
does not possess the physical character which has been
assumed in the case just under consideration.

In most fields all the phosphoric acid necessary for plants
is not distributed in the state in which it is readily avail-
able to the roots. One portion is simply dispersed through-
out it in the form of little granules of apatite only (phosphate
of lime), so that even though the soil may altogether con-
tain more than a sufficient proportion, yet in its various
portions there may exist in some too much, in others too
little, for the wants of plants. The mechanical preparation
of the soil would displace these granules, but would not
cause their thorough distribution and incorporation with .
it. To effect this requires the co-operation of a chemical
action.

After each rye or oat crop there remains in the soil a
considerable quantity of roots, which after one or two years
entirely disappear. We know that these organic matters

THEORETICAL AND PRACTICAL AGRICULTURE. 97

have undergone decay ; that their constituents have united
with oxygen; and that the carbon has formed carbonic
acid, which has accumulated in the air contained in the
porous soil, as analysis shows us.

When rain falls on this soil, it dissolves the carbonic
acid, which thereby acquires the power of taking up phos-
phate of lime. This carbonic acid water does not withdraw
from the soil the phosphate of lime contained in it, but
wherever it meets with the granules of apatite or phospho-
rite, it dissolves a certain portion; for in these granules
there exists no cause of resistance to the action of the water;
and except the cohesion between its own particles, no other
extraneous influence prevents its solubility in water.

Under these circumstances, a solution of phosphate of
lime must consequently be formed, which spreads in all
directions around each granule. Wherever this solution
comes in contact with soil not already saturated with phos-
phate of lime, the soil will take up and retain a certain
portion of this salt. Zhe portion of soil now saturated with
phosphate will oppose no further obstacle to the ge dif-
fusion of the solution.

The same process is found to take place in the diffusion
of the silicic acid and potash in the soil, when the latter
contains silicates which can be decomposed by carbonic
acid. ‘There is then formed around each particle of silicate
a solution of silicate of potash, the constituents of which
are always again fixed, in the first place by the nearest
lying, and then by the more remote portions of the soil.

A certain time is required for the distribution through-
out the soil of the food in the manner above described.

If we suppose that our field had contained 25,000 kilo.
of the ash-constituents of wheat, distributed in the most
uniform manner through it; and in addition to this, but
unequally distributed, five, ten, or more thousand pounds of

5

98 THEORETICAL AND PRACTICAL AGRICULTURE.

the same food, the phosphoric acid as apatite, the silicic aced
and potash as easily decomposed silicates;—if we further
suppose that every two years a certain quantity of the last-
named substances had been rendered soluble, and capable
of distribution in the soil in the manner above mentioned,
and in such proportions that the roots should have found
everywhere in the soil these elements of food in the same
proportions as in preceding years of cultivation—a sufh-
cient amount, therefore, for a full average crop; then
should we, under these circumstances, have obtained during
a series of years full average crops, if we had interposed a
year of fallow between each year of cultivation. Instead of
thirty constantly-diminishing crops, we should in this case
have obtained, during a period of sixty years, thirty full
average crops, if the additional portion of minerals in the
soil had proved sufficient during that time to replace every-
where the phosphoric and silicic acids, and the potash,
removed annually by the crops. With the exhaustion of
the additional proportion of minerals in our field, the period
of diminishing crops would commence; and the further
unterposition from this time of fallow years would not then
exercise the slightest influence on the increase of produce.

In the case under consideration, had the supposed addi-
tional quantity of phosphoric and silicic acids, and potash,
not been unequally but uniformly distributed throughout
the field, and everywhere completely accessible to the roots of
plants, and in a state fit for absorption, then thirty full crops
would have been reaped in thirty successive years, without
the interposition of a year of fallow.

Let us return to our field, in which we assumed that
there were 25,000 kilo. of ailenpatiipents of wheat, tho-
roughly dispersed throughout it, and in a state fit for
absorption, and that it was sown each year with wheat;
let us now suppose that in each crop the ears only were

THEORETICAL AND PRACTICAL AGRICULTURE. 99

cut from the straw, and that the entire straw was left on
the field and imediately ploughed in; then must the loss
of minerals be less in this year than before, for all the con-
stituents of the straw and the leaves have remained in the
ground; we have only removed from the fieid the mineral
constituents of the grain.

Among the substances which the straw and leaves have
obtained from the soil, are found all the constituents of the
seed, but only in altered proportions. If we express by the
number 8, the whole phosphoric acid removed by the grain
and straw together, the loss would be represented by the
number 2, if the straw remains in the ground. The decrease
of produce in a field in a succeeding year bears always a
definite proportion to the loss of mineral substances by the
preceding crop. The following crop of grain will be a
little larger than it would have been, had the straw not
been left in the ground. The produce of straw will be
nearly the same as in the preceding year, for the conditions
for the formation of straw have been but slightly altered.

By thus taking less from the field than formerly, we
thereby increase the number of remunerative crops, or in
other words, the total amount of grain produced in the
whole series of corn crops. <A portion of the straw-consti-
tuents is conyerted into corn-constituents, and in this form

is now removed from the soil. The period of exhaustion \

will always come, but under these circumstances it occurs |

at a later date. The conditions for the production of grain
go on constantly decreasing, for the minerals removed by
it have not been replaced.

This relation would still have remained shies same, had
the cut straw been carted about the field, or been ploughed
in after serving for litter to cattle. What has been sup-
plied to the field in this way, had been originally taken
from it and cannot therefore enrich it. When we reflect

100 THEORETICAL AND PRACTICAL AGRICULTURE.

that the combustible elements of straw are not furnished
by the ground, it is clear that in leaving the straw in the
ground, we really leave only the constituents of its ash.
The field was thereby enabled to yield a little more than
it otherwise would have done, simply because less had been
taken from it.

Had we also along with the straw ploughed in the grain
or its ash-constituents; or instead of the wheat grain re-
turned to the field a corresponding quantity of another
seed, rape-dust (that is, rape-seed freed from its fatty oil),
which contains the same ash-constituents, the composition
of the soil would have remained the same as before, and the
same amount of produce would have been obtained as in the
preceding year.

If after each crop, the straw is always returned in this
manner to the field, the further result then is, an inequality
in the composition of the active constituents of the soil.

We have assumed that our field contained the mineral
matters of the whole wheat plant in the right proportions
for the formation of straw, leaves and grain. By leaving
the straw-constituents in the soil, whilst those of the grain
were constantly removed, an increase of the former took
place, when compared with the proportion of grain-consti-
tuents still remaining in the field. The field retained its
productiveness for straw, but the conditions for the forma-
tion of grain decreased.

The consequence of this inequality is an unequal deve-
lopment of the whole plant. So long as the soil contained
and supplied, in the proper proportions, all the necessary
mineral matters for the uniform growth of all parts of the
plant, the quality of the seed and the proportion between
straw and grain in the diminishing crops remained uniform
and unaltered. But in proportion as the conditions for the
formation of straw and leaves became more favourable, so

THEORETICAL AND PRACTICAL AGRICULTURE. 101

did the quality of the seed deteriorate as its quantity dimi-
nish. The sign of this inequality in the composition of
the soil, as a consequence of cultivation, is the diminution
in weight of the bushel of corn. Whilst at first a certain
portion of the constituents of the returned straw (phospho-
ric acid, potash, magnesia) was expended in the formation
of grain, at a later period the reverse of this takes place,
and demands are then made on the grain-constituents
(phosphoric acid, potash, magnesia) for the formation of
straw. We may imagine that when there exists in a field.
this inequality in the conditions for the formation of grain
and straw, a culmiferous plant may, under conditions of
temperature and weather favourable for the production of
leaves, yield an enormous crop of straw with empty ears.

Vine-dressers and gardeners prune trees and vines in
order to obtain larger fruit and in greater quantity, by
thus limiting the formation of twigs and leaves; and in
many districts, as in lower Bavaria, it is often considered
advantageous to cut down or feed off the corn when half
grown. It is found that by this proceeding a larger amount
and a better quality of grain are obtained. In tropical
regions many culmiferous plants bear no seed, or but a
small quantity, because the soil does not contain the
proper proportion of conditions for the formation of seed
and leaf.

The size of the seed in many plants, is In inverse pro-
portion to the development of the leaf. Tobacco, poppy,
and clover have proportionably smaller seeds than the
culmiferous plants.

The agriculturist can influence the direction of the vege-
tative force only through the soil; that is, through the
proportion of the elements of food which he supplies to it.
For the production of the largest crop of grain ut ws requisite
that the soil contain a preponderating proportion of food neces-

102 THEORETICAL AND PRACTICAL AGRICULTURE.

sary for the formation of seeds. For turnips, leafy and
tuberous plants, this condition is reversed.

An average crop of turnips with leaves contains five
times, a clover or potato crop twice, as much potash as the
grain and straw of a wheat crop from an equal surface. A
clover and a potato crop together remove from two fields
of a hectare each, as much phosphoric acid as the grain of
three wheat crops from three fields of the same size.

It is therefore evident, if we cultivate potatoes and
clover on our field which contains 25,000 kilo. of the mine-
ral constituents of wheat, and remove the whole produce
of tubers and clover, that we withdraw from the soil of
these two fields as much phosphoric acid, and three times
as much potash, as by three wheat crops. It is certain,
that this removal from the soil, by another plant, of these
important mineral substances, produces a great effect on its
fertility for wheat; the yield and the number of the wheat
crops diminish.

If, on the other hand, during a period of two years, we
had cultivated on the field, wheat in the first year, and
potatoes in the second, and had ploughed in the whole of
the potato crop and the wheat straw, and had continued to
do this for sixty years, we should not by these means have
in the least degree altered or augmented the produce in
grain, which the field was capable of yielding. The field
has neither acquired nor lost anything by the cultivation of
potatoes, for these were always left in the field. When the
grain crops taken from the field have diminished the store
of mineral matters to % of their original quantity, then this
field ceases to furnish a remunerative crop, if % of an
average return no longer yield any profit to the agricultu-
rist. We arrive at the same results, if, instead of potatoes,
we had interposed crops of clover, and had in the same
way each year ploughed it in. We have assumed that the

THEORETICAL AND PRACTICAL AGRICULTURE. 108

physical condition of the soil was most favourable, and
consequently, could not be improved by incorporating with
it the organic matters of the clover and potatoes. Even
had we removed the potatoes from the field, mown and
dried the clover, and then carted the potatoes and hay back
to the field, or made them first pass through the cattle
stalls, or made any other use of them; had we in this way
returned to the field the whole sum of mineral matters in
both crops, we should not by all these operations have pro-
duced from it in thirty, sixty, or seventy years, a single
grain more than would have been obtained without all these
changes. During this whole period the conditions for the
production of grain have not increased, but the cause of
decrease in the crops has remained the same.

The ploughing in of the potatoes and clover could pro-
duce a beneficial effect only on those fields, in which a
favourable physical state did not exist; or in which the
mineral matter was unequally distributed, and was partly
inaccessible to the roots of plants. But an action of this
kind is just the same as that of green manuring, or of one
or more years of fallow.

By the incorporation with the soil of the clover and
organic substances, the amount of decaying matters and of
nitrogen in itis increased from year to year. All that these
plants received from the atmosphere remained in the
ground, but the enriching of the soil with these otherwise
useful matters cannot effect the production of more grain
than formerly ; for this depends on the proportion of the
minerals in the soil, and these have not been increased, but
on the contrary, have constantly decreased, in consequence
of the removal of the corn. By the increase of nitrogen,
and of decaying organic matter in the soil, the produce
might possibly be augmented for a number of years, but
the period at which such land would no longer produce a

104 THEORETICAL AND PRACTICAL AGRICULTURE.

remunerative crop, occurs in such circumstances only so
much the more quickly.

If we cultivate on three different wheat fields respec-
tively, wheat, potatoes, and clover, and plough all the
potatoes and clover yielded by the other two into the
wheat field, from which the grain alone is removed, we
shall by these means render the latter more fertile than
before, for we have enriched it by the whole amount of
minerals which the potatoes and clover had extracted from
the other two fields. It has received three times as much
phosphoric acid, and twenty times as much potash, as the
grain has carried away.

This wheat field will now be able to produce in three
successive years, three full grain crops; for the conditions
for the production of straw have remained unchanged,
whilst those for corn have been increased threefold. If
the agriculturist in this manner raises in three years as
much corn as he would have done in five on the same fields,
without the co-operation of the mineral constituents of the
clover and potatoes, then has his profit now evidently become
greater, for he has reaped with the seed for three crops as
much as he would have done in the other case, with the
seed for five. But the other two fields have lost in fertility
as much as the wheat field has gained; and the final result
is, that with less cost of cultivation, and with more profit than
before, the agriculturist has in his three fields anticipated
the period of exhaustion which would inevitably have over-
taken them by the continued withdrawal in grain of the
mineral constituents of the soil.

The last case that we have to consider is, when the agri-
culturist, instead of potatoes and clover, cultivates turnips
and lucerne, which, by means of their long and deep pene-
trating roots, extract a large quantity of mineral matter
from the subsoil, which is not reached by the greater num-

THEORETICAL AND PRACTICAL AGRICULTURE. 105

ber of the roots of the cereals. Where the fields possess a
subsoil, favourable to the growth of these plants, we double,
as it were, the extent of surface capable of cultivation. If
the roots of these plants received half of their mineral
matters from the subsoil, and the other half from the arable
soil, the latter will lose by the crops only half so much as
they would have done, had the whole of the mineral food
for these crops been obtained from the arable soil alone.

The subsoil considered in the light of a field apart from
the arable soil, thus furnishes to the turnip and lucerne
crops, a certain quantity of mineral matter. If we sup-
pose that in harvest the whole of the turnip and lucerne
crops had been ploughed under in the wheat-field, which
had yielded an average crop of grain, and in this way as
much and more mineral matter had been returned than the
grain had removed; then by these means, this wheat-field
can be maintained at the sume degree of fertility at the expense
of the subsoil, just so long as the latier continues productive for
turnips and lucerne.

But since turnips and lucerne require for their growth a
very large quantity of mineral matter, the subsoil will be
the sooner exhausted, in proportion to the smaller quantity
of these substances it contains. Now as the subsoil is not
in reality separated from the arable soil, but lies beneath it,
it can scarcely receive back any of the substances it has lost,
because the arable soil retains that portion of them which
has been added to it. It is only that part of the potash,
ammonia, phosphoric, and silicic acids, which has not been
taken up and fixed by the surface soil that can penetrate
to the subsoil.

By the cultivation of these deep-rooting plants, super-
abundance of food can consequently be obtained for all
_ those which derive their nourishment chiefly from the sur-
face soil. This supply will not, however, be of any dura-

5*

106 THEORETICAL AND PRACTICAL AGRICULTURE.

tion; for, in a comparatively short time, many fields will
cease to produce these plants, because the subsoil is ex-
hausted, and its fertility is only restored with difficulty
In the first place, lucerne no longer grows, and turnips are
only now produced in so far as they are able to obtain theiz
full supply of minerals from the surface soil. Potatoes,
which derive their supplies from the upper layers of the
surface soil, endure the longest.

The quantity of food which a plant receives from the
ground is not alone dependent on the quantity which is
present in the finest particles of the surface soil, but also
on the number of organs which extract this food from the
ground. ‘Two roots will obtain twice as much as one.

The crop is partly dependent on the first root forma-
tion.

A grain of wheat or barley contains within itself so large
a quantity of food, that it stands in no need of the soil in
the first period of its growth. The seeds of these plants
when simply moistened, produce ten or more rootlets from
six to eight lines in length. The heavier the grain, the
stronger and more vigorous is the formation of roots. The
seed corn, without receiving anything from the ground,
extends in all directions its organs of absorption, by which
it procures its food from a comparatively great distance.
Hence the agriculturist attaches great importance to the
careful selection of seed.

Small seeds, such as those of tobacco, poppy, and clover,
require a richer or more thoroughly prepared surface soil,
to prevent the loss of a large proportion; because the soil
in the immediate neighbourhood of the seed must at once
supply it with food after germination. Hence, as the agri-
culturists say, such plants are more difficult to raise.

The seeds of the cereals may be compared to a hen’s
egg, which contains within itself all the necessary elements

THEORETICAL AND PRACTICAL AGRICULTURE. 107

for the development of the young animal. Husbandry ,
would certainly assume quite another form, if for every
single cereal plant, as many seeds should be lost as is the
case with poppies, tobacco, and even clover.

The quantity of food which a plant obtains from one and
the same soil is in proportion to its absorbent root surface. Of
two species of plants, which require the same quantity and a
sinular relation of mineral food, the one with double extent of
root surface takes wp double the quantity of food.

If it is true that the constituents of the ash of plants are ©
indispensable to their life and growth, it is evident that
whatever else may exert a favourable influence on their
growth, must be subordinate to the law, that the soil, in
order to be fertile in an agricultural sense for a cultivated
plant, must contain the constituents of the ash in sufficient
quantity, and in a state the most suitable for absorption.

The agriculturist has to do with the soil alone; it is only
through it that he is able to exercise an immediate influ-
ence on plants. The attainment of all his objects in the
most complete and profitable manner, pre-supposes the
exact knowledge of the effective chemical conditions for
the life of plants in the soil ; it further pre-supposes, perfect
acquaintance with the food of plants, and the source from
which it is derived, as well as with the means for rendering
the soil suitable for their nutrition, combined with experi-
ence and skill in employing them in the proper way, and
at the right time.

It is evident from the above statement that the cultiva-
tion of plants tends to drain or to render a fertile soil un-
productive. In the produce of his fields destined for the.
food of man and beasts, the agriculturist sends away that
portion of the active ingredients of his soil which con-
tributes to the growth of this very produce. The fertility
of his fields continuously diminishes, whatever may be the

108 THEORETICAL AND PRACTICAL AGRICULTURE.

plants he cultivates or the rotation he adopts. The export
of his produce is nothing else than a spoliation of his soil
of the conditions for its reproduction.

A field is not exhausted for corn, clover, tobacco, and
turnips, so long as it still yields remunerative crops with-
out requiring restoration of the minerals which are removed.
tt is echausted from the moment that the hand of man is
needed to restore to it the failing conditions of its fertility.

The great majority of our cultivated fields are tn this sense
exhausted.

The life of men, of animals, and of plants, is connected
in the closest manner with the return of all the conditions
which promote the vital process. The soil by its constitu-
ents contributes to the life of plants; its continuous fer-
tility is inconceivable and impossible without the return of
those conditions which have rendered it productive.

The mightiest stream, which sets in motion thousands of
mills and machines, fails, if the streams and brooks run dry
which supply it with water; and these streams and brooks
in their turn dry up, if the myriads of little drops of which
they consist do not return in the form of rain to those
spots from which they have their source.

A field which has lost its fertility by the successive cul-
tivation of different plants, acquires by the application of
farm-yard manure, the power of producing a new series of
crops of the same plants.

But what is farm-yard manure,’and whence is its origin ?
The land of the husbandman is the source of all this
manure. Manure consists of the straw which has served
for litter, of the remains of plants, and of the fluid and
solid excrement of man and animals. The excrement is
derived from the food.

In the bread which a man daily receives, he consumes
the ash-constituents of the seeds of the cereals whose flour

THEORETICAL AND PRACTICAL AGRICULTURE. 109

has served for the preparation of the bread; in flesh, the
ash-constituents of flesh.

The flesh of herbivorous animals, as well as its ash-con-
Stituents are derived from plants. These ash constituents
are identical with those of the seeds of leguminous plants ;
so that if a whole animal were burnt, the residual ash
would not differ from that of beans, peas, and lentils.

In bread and flesh, man consequently consumes the
mineral matters of seeds, or of the constituents of seeds,
which the ‘agriculturist obtains from his land in the form
of flesh.

But a very small fraction of the large amount of mineral
substances received by man in his food during a lifetime re-
mains in his body. The body of an adult does not increase
in weight from day to day, it therefore follows, that all the
constituents of his food have passed again completely out
of his body. Chemical analysis demonstrates that the ash
of bread and of flesh exists in his excrement very nearly in
the same quantity as in his food. The comportment of the |
food in his body is just the same as if it had been burnt in
a furnace. The urine contains the soluble, and the fzeces
the insoluble mineral matters; the bad smelling ingredi-
ents are the smoke and soot of an incomplete combustion.
With these are also mingled the undigested and indigesti-
ble remains of food.

The excrement of swine fed on potatoes contains the ash-
constituents of potatoes; that of the horse, the mineral
matters of hay and oats; that of cattle, the ash of turnips,
clover, &c., which have served for their food. Farm-yard
manure consists of a mixture of all these excrements
together.

By farm-yard manure, the fertility of a field which has
been exhausted by cultivation, is completely restored. This
is a fact which the experience of thousands of years has

110 THEORETICAL AND PRACTICAL AGRICULTURE.

established. In farm-yard manure the field receives a cer-
tain quantity of organic, that is, combustible matter, and the
ash-constituents of the consumed food. We have now to
consider what part was played by the organic and inorganic
matter in this restoration of fertility.

The most superficial examination of a cultivated field
shows, that all the combustible matter of plants which are
reaped from the field are derived from the air, and not from
the soil.

If the carbon of only a portion of the vegetable matter in
the crop were derived from the soil, it is perfectly clear, that
if the latter contained at first a certain amount of this element
before the harvest, this quantity must become smaller after
each crop. A soil poor in organic matter would be less
productive than one in which it is abundant.

Observation, however, shows, that a field under continued
cultivation does not in consequence become poorer in organic
or combustible matter. The soil of a meadow, which during
ten years has yielded a thousand cwt. of hay per hectare, is
not, after this period, poorer, but richer in organic substances.
A clover field, after a crop, retains in the roots remaining in
the soil more organic matter, and more nitrogen than it
originally possessed; but it has become unproductive for
clover, and yields no longer a remunerative crop.

A wheat or potato field is in like manner, after a crop,
not poorer than before in organic matter. Jn general the soil
ts enriched by cultivation with combustible constituents, but tts
fertility nevertheless steadily diminishes. After a number of
consecutive remunerating crops of corn, turnips and clover,
these plants are found to flourish no longer on the same soil.

Since, then, the presence of decaying organic matier in a soil,
does not in the slightest degree retard or arrest ts exhaustion by
cultivation, tt is impossible that an increase of these substances
can restore the lost capacity for production

THEORETICAL AND PRACTICAL AGRICULTURE. 111

In fact by incorporating with the soil of a field com-
pletely exhausted, boiled saw-dust, or salts of ammonia, or
both together, we cannot restore to it the power of yielding
a second or third time the same series of crops. If these
substances improve the physical character of the soil, they
will exercise a favourable influence on the produce; but
after all, their action still consists in accelerating the exhaus-
tion, and rendering it more complete.

Farm-yard, manure, however, restores thoroughly the
power of producing the same series of crops, a second, third,
or a hundred times. It arrests fully, according to the
quantity employed, the state of exhaustion; its application
may render a field more fertile; in many cases more so than
it has ever been.

The restoration of fertility by farm-yard manure cannot
have been caused by the presence of combustible matters
(carbonaceous and nitrogenous substances). If these pro-
duced any good effects, they were of a subordinate nature.
The action of farm-yard manure depends most undoubtedly on
the amount of the incombustible ash-constituents of plants i it,
and ws determined by these.

In the farm-yard manure the field received back in fact a
certain quantity of all the minerals which had been with-
drawn by the crops. The decrease in its fertility stood in
exact relation with the removal and the restoration of the
fertility with the restitution of these mineral substances.

The incombustible elements of cultivated plants do not
of themselves return to the soil like the combustible in the
atmospheric sea from which they are derived. By the hand
of man alone are the conditions of the life of plants given
back to the soil. By farm-yard manure, in which these con-
ditions are fulfilled, the agriculturist, as if by a law of nature,
restores to his field its lost powers of production.

A rational practice maintains the circulation of all the

112 THEORETICAL AND PRACTICAL AGRICULTURE.

conditions of life; and empirical practice breaks the chain
which binds man to his home, by robbing the soil of one
condition after another of its fertility. Though the empiric
knows that the soil is different to-day from what it was
yesterday, he nevertheless believes that it will be to-morrow
what it is to-day. Founding on the experience of yesterday,
he teaches that the fertile soil is enexhaustible ; but science,
guided by laws, shows that the productiveness even of the
most fertile soil, has its end, and that the very soil which
appears inexhaustible, is exhausted. Because nature was
kind and gave abundantly to the father, the empiric thinks
that the son may also take abundantly and without any
care for the future. On the fact that man has a home, and
that the spot of earth, from which he toils with the sweat
of his brow to gain his subsistence, is his home, depends the
development of the human race. The continuance of his
existence in his home is dependent on the law, that yotes as
expended by use and maintained by supply.

LETTER IX.

Constant relation between the Sulphur and Nitrogen of Organic Compounds
and the Alkaline Phosphates and Alkaline Earths of Cereals and Legu-
minous plants—Mineral substances are as indispensable to the Life of
Animals as to that of Plants—The amount of Phosphoric Acid and of
Potash ascertained by analysis as existing in Soils is very small—The
errors of Practical Teachers proved from the writings of Practical Agri-
culturists—Fertility of land cannot be maintained by Nitrogenous and
Carbonaceous Manures alone, but by the Restoration of the Ash Constitu-
ents of Plants—Critical examination of the views o Walz, a practical
teacher, on the Nutrition of Plants—The mineral food of plants in arable
soils is not inexhaustible—The volatile and organic matters of Manures
are not the most important—The nature of Guano and its active con-
stituents.

THE life and development of an organic being cannot be
regarded as depending on chance. The assimilation of its
food, the transformation of the elements of this food into
living forms, and all organic processes, we find are go-
verned by laws of necessity and reciprocal dependence,
which, like the wheels of a machine, but in an infinitely
more perfect manner, play into each other, and give rise to
all its vital manifestations, its existence and continuation.

Chemical analysis has shown that in the seeds of the
cereals and of the leguminous plants, those sulphur and
nitrogen constituents which, in the process of nutrition of
men and animals, are employed in forming the combustible
matters of blood, are always accompanied by alkaline phos-
phates and alkaline earths, and that between both there ex-
ists for each seed a fixed and unchangeable relation. When-
ever the percentage of phosphoric acid increases or dimi-

114 THEORETICAL AND PRACTICAL AGRICULTURE.

nishes in any seed, we observe a like increase or diminution
in the sanguigenous constituents.

Chemical analysis has further shown that, in the blood
of man who consumes bread, or in that of a warm-blooded
animal fed on seeds, there exist the same incombustible
matters as are contained in the food. The ash-constituents
of the blood of cattle, sheep, swine, correspond to the
ash-constituents of the turnips, herbs, or potatoes on which
these animals have subsisted.

The mineral elements of all the different parts of plants

are, however, as indispensable to the life of animals, to the
formation of their blood, and to its functions, as they are
to the life of plants.
' Phosphoric acid is a constituent of the brain and of the
nerves; the alkaline phosphates and alkaline earths exist
in the flesh of all animals: and a warm-blooded animal
without bones (phosphate of lime), is inconceivable to us.
The ash of green crops is rich in alkaline carbonates and
common salt; and the blood of herbivorous animals
abounds in alkaline carbonates, the chloride of sodium
serving for the formation of the carbonate of soda of this
fluid. ‘T'ea-leaves, of which man makes so much use in in-
fusion, contain in their ash 17 per cent. of phosphoric acid ;
in mulberry leaves, the food of the silkworm, the amount
does not exceed 5 per cent. Hach of these numbers has its
physiological meaning.

Were it possible for a plant to grow, flower, and bear
seed without the co-operation of mineral matters, it would
be utterly valueless to man and animals. A dog will die
of hunger in presence of a dish full of raw or boiled white
and yolk of eggs, in which is awanting one of the sub-
stances most important for the formation of blood. The
first trial teaches him that such food is as inefficient as a
stone for the purposes of nutrition.

THEORETICAL AND PRACTICAL AGRICULTURE. 115

The constituents of the ashes of turnips and of meadow
plants give them their nutritious value. Did they not exist
in them, such plants would not be consumed by horses and
cows.

Everywhere in nature prevail those harmonious laws,
which attach life to the earth, and maintain it in perpetual
freshness and duration. Only there does the earth become
old, and the germ of life is extinguished, where man in his
narrow-mindedness ignores and denies their existence, when
he opposes the circulation of the conditions of life, and de-
ranges and obstructs their united action.

It is certainly one of the most singular, if not one of the
most inexplicable circumstances of the present day, that
the existence of these natural laws is ignored by a great
number of practical agriculturists,—precisely by those men
who, in their occupation, are in a position to perceive
daily the signs of their existence. Teachers of practical
agriculture universally recognised to be the most distin-
guished and skilful, have for sixteen years, and even up to
a recent period, endeavoured to prove that these laws have
no value in connection with fertile soils; that the increase
of the fertility of a field by fallow and by mechanical opera-
tions, and the removal of the mineral matters of the soil in the
crops, do not diminish the duration of this fertility: that the
ground may retain continuously rts fertility even when they
neglect to supply the minerals which have been withdrawn,
that is, fo restore the original composition of the soil. They
teach that a fertile field contains an inexhaustible amount of
the ash-constituents of plants, and that, consequently, de-
ficiency of these can never occur in it; that the fertility of
a soil is in exact proportion to the quantity of combustible
matters, of humus and nitrogen in it; and that the want of
_ fertility is owing to the want of nitrogen, and that the ex-
haustion of the land depends upon the withdrawal of the

116 THEORETICAL AND PRACTICAL AGRICULTURE.

latter. Manure, they assert, does not produce its beneficial
effects by returning to the ground those elements which
have been withdrawn from it in corn, clover, turnips, to-
bacco, flax, hemp, madder, wine, &c., but it acts by its com-
bustible constituents, and its effect is in proportion to the
amount of nitrogen it contains. Its incombustible elements
only quietly look on to see how the other matters are doing,
something in the same way as the moon does when the dew
is falling.

The practical man regards with a smile of contempt the
scientific proofs of his errors, but this smile does not arise
from the feeling of conscious superiority which knowledge
imparts, but it has its origin in a different source.

Chemical analysis has with its rigorous methods proved,
that of thousands of fields there is scarcely one which con-
tains more than 1 per cent. of the ash-constituents of plants,
of clover, for instance, in a state suitable to the wants of
that plant.

In 1848 the Royal Institute of Rural Economy in Berlin
caused the soil from fourteen different places of the king-
dom to be submitted to chemical analysis. The specimens
were taken from fields which were as much alike as possi-
ble, and a portion of each specimen handed to three different
chemists for analysis. It resulted from these analyses that
the mean quantity of phosphoric acid and potash (the latter
in a state probably fit ba assimilation) amounted, ” five
fields to 75; in six, to 4 up to ~;; and in three, to ;4 up
to 3%; per cent.

These analyses do not teach that a soil which contains $
per cent. of these mineral substances is in consequence
more fertile than another in which there exists only #; per
cent.; but they show with tolerable certainty that it con-
tains a greater or less proportion of them.

Practice, on the other hand, asserts that every soil con-

THEORETICAL AND PRACTICAL AGRICULTURE. 117

tains the ash-constituents of all plants in inexhaustible
quantities.

Chemical analysis points out in the most positive and
undoubted manner, that a crop of clover removes from the
soil in its ash-constituents a number of the conditions of
its fertility for this plant; it shows that, in the excrement
of animals fed on clover, are contained the ash-constituents
of clover, and that consequently, by the employment of
such a manure, the whole of these ash-constituents which
have been removed by the clover are again restored to the
land.

As harmonising with the scientific doctrine, that the
exhaustion of a clover field really depends on the removal
of the ash-constituents of the clover, and the renewal of its
fertility by farm-yard manure, on the restoration of these
same mineral matters, the writings of the most experienced
agriculturists show, that a field which produced no clover,
can be made productive for a series of such crops by manur-
ing with wood-ashes, which contain the same mineral matters
as clover; that in the Netherlands this manure is of the
most general application for this purpose; and that in
Westphalia there is a proverb that “he pays double who
buys no ashes.” (Schwerz, Anleitung zum prakt. Ackerbau,
Bd. ii. 8. 823.) It is a well-known fact that on strewing
wood-ashes on a meadow, thousands of clover plants make
their appearance where they were not visible before.

Chemical analysis further shows that a similar relation
exists between a soil and all plants which are grown upon
it; that a field which will no longer yield grain, but straw,
bears a rich crop of the former if it has been manured with
the ash-constituents of grain, and in many cases even with
phosphate of lime alone.

In complete opposition to the modern doctrine of our
agriculturists, it is proved by indisputable facts that the fer-

118 THEORETICAL AND PRACTICAL AGRICULTURE.

tility of the soil is not increased by the amount of organic
or combustible matters in it, or by the supply of these
alone; that a soil which contains these in the greatest
abundance is, as a rule, unproductive; and that the appli-
cation on a wheat field of nitrogenous matters—such as the
salts of ammonia—in many cases diminishes rather than
increases the crop of grain. It has further been proved
that ammonia and nitrogenous manures do not augment
the produce of clover, unless accompanied by the ash-con-
stituents of the plant; that by themselves they act favour-
ably, only on such fields as are rich in mineral matters;
and that their continued use in such cases only more com-
pletely exhausts the land—that is, makes it still more
unproductive for future crops than it would have been
without their action.

Tf our fields really contained so large a quantity of the
mineral matters of plants that they could not be exhausted
by cultivation; if the fertility was dependent on the pre-
sence and their exhaustion on the absence of ammonia or
nitrogenous substances, then an endless series of full crops
should be obtained by the supply of these alone, without
the addition of any mineral matter. It is, however, an
established and indisputable fact, that the maintenance of
the fertility of our fields is ¢mpossible without replacing the
minerals withdrawn by the crops. Hence it follows that
farm-yard manure does not act by its combustible elements,
and that if the latter in any case produce a favourable effect,
it is only when they are accompanied by the ash-constitu-
ents of plants which have been removed by previous crops,
and which are awanting in the field.

I believe that among the readers of these letters there
will scarcely be found one, at all acquainted with the rules
of logic, who could have any doubts of the truth of the
conclusions deduced from the chemical analysis of the sozl,

THEORETICAL AND PRACTICAL AGRICULTURE. 119

of plants, and of farm-yard manure. These analyses have
been made in thousands by different chemists in Germany,
England, and France, and all agree perfectly in their results.
If indeed the existence of a fact can be ascertained by the
balance, there is none in the whole domain of chemistry
more firmly established than this, that even the most fertile
soil contains but an extraordinarily small quantity of the
ash-constituents of plants in comparison with its chemically-
inactive mass. It will be sufficient to give an idea of this
fact when I state that the ablest chemists failed in discover-
ing, before 1834, potash as a constituent of soils, of clay,
and of limestones, because its amount is so small; and that
before the discovery of new and hitherto unknown re-agents,
the simple detection in the soil of phosphoric acid (without
any attempt to ascertain its quantity) was attended with
the greatest difficulty. In these statements we find a justifi-
cation of the views formerly held by philosophers that pot-
ash, lime, and phosphoric acid are products of the vital pro-
cesses or of the vital force.

As is well known, there is an infinite variety in the com-
position of the rocks and minerals, by the disintegration of
which soil is formed. There are minerals which are rich
in potash, and which, like felspar, contain no lime; in
others, silicic acid or magnesia is awanting, or like lime-
stones, they contain only traces of alkalies. It is only in
exceptional cases, and in those rocks which are not exten-
sively distributed, that it has been possible to estimate by
chemical analysis the weight of the phosphoric acid pre-
sent.

Like gold in the gold districts of America and of Australia,
arable soil is the residual matter of rocks shattered by
mighty mechanical actions, and decomposed by chemical
causes. The granite gravel in the neighbournood of Darm-
stadt, in which can be detected felspar, mica, and quartz,

120 THEORETICAL AND PRACTICAL AGRICULTURE.

is as unproductive as pure quartz or pounded marble. A
thousand years are perhaps necessary to form from many
rocks, from basalt, granite, porphyry, trachyte, &c., a layer
of arable soil, a line thick, such as is seen in wide valleys
and low grounds, and to give it the physical and chemical
properties which render it suitable for the growth of plants.

Our modern teachers of agriculture inculcate that a fruit-
ful soil is inexhaustible in the ash-constituents of plants,
which are the essential conditions of their existence; and
the present system of agriculture is, in all its relations,
based on this view, and on the further supposition that the
increase of the produce of the ground can only be effected,
or chiefly so, by the supply of organic matters, the ele-
ments of which are obtained, not from the soil, but from
the air.

Practical agriculture asserts, that in such practical ques-
tions which refer to sozls, crops, and manures, geology and
chemistry have no voice; experience alone can decide in
such cases, and the deductions of science are not confirmed
by it.

We will now examine a little more narrowly the nature
of this experience, and the grounds on which she bases her
teaching. If founded in truth, 2 must secure the duration of
the fertility of productive soils: it must provide practical
agriculturists with the means of restoring to their land the
fertility lost by cultivation. If those who follow such
teaching are ever in want of these means, then is its con-
demnation pronounced.

Since the commencement of the contest regarding the
scientific principles of agriculture, many excellent agricul-
turists have communicated to me the most interesting
proofs, from their own practice, of the truth of these prin-
ciples, which they have hesitated to publish in an agricul-
tural journal, through fear of being involved in a discus-

THEORETICAL AND PRACTICAL AGRICULTURE. 121

sion, which, as they very modestly expressed it, they had
not sufficient scientific knowledge to carry on. In the po-
sition which I occupy, I stand, as may be supposed,
towards agriculturists who cultivate their own land, only in
social relations of the most instructive and agreeable nature
to myself; when, therefore, in these letters, I speak of
practical agriculture, or practical agriculturists, as a matter
of course only literary practical agriculturists are meant,
and those who write and lecture in support of the doctrines
of the school to which they belong. Among our agricul-
turists are to be found many men of the greatest intelli-
gence and information, who, like the gentleman, general,
lawgiver, and consul of Rome’s best age, follow, from in-
clination, agriculture as the noblest occupation, and manage
their own estates. No one can reasonably expect that
such men are to account for views and doctrines which
are not theirs, but which they have adopted as they were
taught.

A totally different relation, however, exists between
science and the writers on practical agriculture, whose com-
petence to pronounce an opinion on the present important
questions may not be disputed. From such men it must
absolutely be required that they bring to the discussion of
such questions, so much of the rudiments at least of che-
mistry, physics, and geology, as are usually taught in
ordinary schools, so that no doubts may be raised as to their
intellectual capacity to comprehend correctly the questions
at issue.

The simple statement of the views and doctrines from his
last work, of one of the ablest and most influential teachers
of agriculture, as to the composition of the soil, the causes
of its fertility and exhaustion, and the action of manures,
will be sufficient to enable us to form an opinion on this
point. This publication is expressly intended by the

6

122 THEORETICAL AND PRACTICAL AGRICULTURE.

author to correct scientific teaching, aud to bring it into
harmony with practical experience.*

In the application of his theory to practice, the author
of this publication puts forward as a fundamental principle
that, “the soil (the surface and sub-soil included), may be
said to contain an inexhaustible supply of those mineral
elements of food which it received at first from nature, and
furnishes by disintegration to plants.”—(s. 116.)

The following proposition is propounded by him, “Is
the soil of a field of such a nature that it can be completely
exhausted in a shorter or longer period of its soluble and
insoluble mineral matter, if we do not restore to it the por-
tion which is taken away by the crops?” and it is answered
in the following way :—(s. 28.)

‘“‘ The soil consists of disintegrated rocks, and either rests
upon these same rocks or on others elsewhere; the trans-
ported soil may, nevertheless, have remained the same,
and corresponds at least to the rocks from which it has its
origin (p. 29, &c.).

“ All rocks undergo disintegration, and the products
when not removed remain resting upon these rocks. The
disintegration is chiefly effected by atmospheric causes,
which extend their action down to the rocks lying deep
under the débris. If, then, a soil is fertile for a given class
of plants, and contains the mineral food for these plants in
sufficient quantity, in proper proportions, and in a state fit
for assimilation, and if it still rests upon the original rocks
from which it was produced, then these underlying rocks also
contain the same mineral food as the soil and subsoil, and in
the same proportions.

* “On the Nutrition of Agricultural Plants. An Examination, in an
Agricultural Point of View, of the Fifty Axioms of Baron Liebig,” by Gustav
Walz, Director of the Agricultural Academy at Hohenheim, Stuttgart. Cotta,
1857.

THEORETICAL AND PRACTICAL AGRICULTURE. 123

“Tf we withdraw from the soil its constituents by crops,
its volume diminishes, and the rocks are thereby rendered
more accessible to the action of the atmosphere. If the
disintegration of the latter proceed in the same ratio as the
constituents of the soil above them are withdrawn, then
shall we be able to obtain crops from it without restoration
of the mineral matters, until the whole quantity in the soil,
and in the rocks, be consumed.

“Suppose the soil of an hectare field (24 acres), weighs
44 millions kilogrammes, and contains 10 per cent. of the
mineral food of wheat plants in the right proportions and
in a state fit for assimilation, such a field could, without
any further supply, produce 1829 corn-crops. A three-
crop rotation could last 2742 years without restoration of
the mineral matters; and were the rocks at the commence-
ment of the tillage already disintegrated to the depth of
several feet, as us generally the case, then the three-crop
rotation would have the prospect of enduring for each foot
depth of earth other 2742 years. After this period, how-
ever, the rocks under the subsoil will again undergo further
disintegration, and thus there is a prospect of continuing
tillage until the rocks forming the soil are entirely disin-
tegrated, and the mineral constituents consumed. But
there comes then another class of rocks under these, &c., &c.

‘“‘By yearly removing ash-constituents from the soil, its
volume is reduced. The agriculturist, however, preserves
a soil of the same depth by turning up an equal quantity
from the subsoil. If all the mineral food in the soil has
been consumed, we have lost 10 per cent., and turned up
10 per cent. from the subsoil. The turned up mass of
earth, however, only contains 10 per cent. of mineral food.
Hence, only ;4 of the withdrawn matters is replaced, the
remaining 3; being waste matter. The second period of
the supposed three-crop rotation would therefore not last

124 THEORETICAL AND PRACTICAL AGRICULTURE.

2742 years, but only ; of this time, viz., 274 years; it is
only after several such periods that the field would be ex-
hausted. Jn the end there would remain nothing but insoluble
silica and clay. To maintain the fertility of this soil in
mineral matters, the withdrawn ash-constituents must again
be supplied to the soil, or the waste matter lying on the
subsoil be removed. In this operation nature helps us by
yearly washing away the soil, in proportion to its greater
or less inclined position. Finally, with respect to the re-
placement of mineral matter in the soil, even rain, and
wind also, assist in supplying them.

“Thus, the restoration required, after a shorter or longer
time, of the mineral matters removed by crops, in such a
soil as we have supposed above, may take place only after
thousands of years; in a soil with 1 per cent. of mineral
matters, after hundreds of years; and with 4 per cent.,
after tens of years.

“The transported soil comports itself in a similar manner
to the untransported ; the rocks lying under it will likewise
undergo decomposition, &c., &c.”

Our teacher of practical agriculture concludes his argu-
ment with these words: “ The two axioms, viz.,

Ist, ‘‘The increase of the fertility of a field by fal-
low and mechanical operations, and the removal of
the mineral substances in the crops without replacing
them, are followed, after a longer or shorter period, by
continued sterility ;” and,

2ndly, “If the soil is to preserve permanently its
fertility, the mineral matters withdrawn from it must,
after a shorter or longer period, be replaced; that is,
the composition of the soil must be again restored,”

these two points apply, therefore, in our time, only to soils of
the very worst description, which required from the very com-
mencement a supply of these substances.” (W.S. 84.)

THEORETICAL AND PRACTICAL AGRICULTURE. 125

The above argument of one of our best teachers of prac-
tical agriculture, which professes to harmonise with his
agricultural experience, might well awake, in the minds of
many of our reflecting agriculturists, just doubts as to the
truth of the prevailing system of agricultural teaching.

Sound common sense demands, in proof of the proposi-
tion, that only the very worst kinds of soil require for the pro-
duction of further crops, the restoration of the withdrawn
mineral matters—that numerous instances should be adduced
from common agricultural experience that a fertile soil, in
order to continue productive, stands actually in no need of
this supply of these matters; that for ten, twenty, or a
hundred years, it has annually yielded crops without any
replacement whatever of the withdrawn minerals!

This proof, the only one which the writer from his point
of view could adduce for refuting the results of the chemical
analysis of soils, he still owes us, as well as the proper defi-
nition of his notion of a “fruitful field.” It is evident,
that if the term “fruitful field” includes only those fields
which exist as exceptional cases in Hungary, in many parts
of Russia, in low lands and valleys, and which are used as
meadows, and appear to be inexhaustible because they are
not yet exhausted, then the soil of ninety-nine out of every
hundred fields that are called fertile in Bavaria, Prussia,
and Saxony, belongs to the worst kinds—a view, which no
one can support.

Our teacher of practical agriculture does not pay any
attention to these actual facts, but brings forward his proofs
in his own peculiar way. Without telling us what he
understands by rocks, soil, and subsoil, and what kinds of
rock, soil, and subsoil he means, he proceeds to apply these
terms as if all soils, rocks, and subsoils were identical; and
leads us to believe that all soils, after their exhaustion by
crops, leave, as a residue, quartz and clay. Such an asser-

126 THEORETICAL AND PRACTICAL AGRICULTURE.

tion, however, he would not seriously make, for in that
case a great part of Wurtemberg would be without any
soil.

To come to an agreement in a discussion, people must
understand each other; for if the one individual means by
a word, sometimes one thing, and sometimes another, it fol-
lows that the other cannot understand him; for, in order
to understand, we must have distinct ideas. A scientific
definition is nothing but an ordinary one, only definite and
unchangeable in its meaning.

If an agriculturist speaks of his cattle which give him
milk and manure, his neighbour agriculturist understands
that he means his “cows.” The production of milk and
manure does not, however, constitute the scientific defini-
tion of a “cow,” for it does not exclude the idea which
might be entertained by a third person that all animals
which produce milk and manure are cows, or that a cow
which gives only manure and no milk is not a cow.

The same holds good in chemistry with the notion con-
veyed by the word sozl, and also with regard to what is
called experience; the word experience in an unscientific
sense always recals to mind the man who was seized with
sneezing when it thundered, and who always went out
with his umbrella in the most beautiful weather, if he had
happened to sneeze in the morning, because, according to has
experience, it was sure to be a thunder storm.

In the argument of our teacher of agriculture, there is,
in fact, ‘no soil””—that is, nothing which an agriculturist
from experience knows as such; but it cannot be denied
that the argument takes a wide range and view of things.

The diminution of volume of the soil by the removal of
mineral substances is evident; amounting yearly, if my
calculation does not mislead me, in the three-crop rotation
to the ~; part of the thickness of a spider’s thread.

THEORETICAL AND PRACTICAL AGRICULTURE. 127

Equally clear and intelligible is the way in which nature
is made to help plants, when the surface soil is exhausted,
to obtain their nourishment from the sub-soil. The soil is
in this respect made to comport itself to plants somewhat
hike a mixture of 2, of quartz and ;4 of peas to a brood
of fowls. When these birds have picked the peas from
the soil, then comes the cock, like nature, afterwards, and
scratches and scrapes away the useless matters. The saga-
city of our teacher will of course also explain what becomes
of those four million kilogrammes of waste matter which
are yearly washed away in this manner from 1829
hectares; as well as show that the loss of mineral matters
is of no importance to those neighbouring fields from which
the wind and rain have carried them to our own.

The experienced teacher of practical agriculture, in order
to refute a deduction of exact science which he holds to be
false, invents a case which does not exist in nature, and is
simply impossible, or at least unknown; and the conclu-
sion to which he had previously carefully prepared his pre-
mises to lead, he applies to actual cases. He imagines a
fertile field extremely rich in the ash-constituents of plants,
and supposes it to gain from below, in the most dexterous
manner, what is taken from the surface; and having in
this way made it inexhaustible, he then draws the con-
clusion that all fields which are fertile, must comport them-
selves exactly like this imaginary field. It follows, then,
as a matter of course, that the worst soils, under which can
be understood only those which are absolutely sterile, must
have required a supply of ash-constituents from the very
beginning; for it is impossible to assume that, in the
absence of all mineral food, which is taken for granted to
_ be the case, they could have produced crops without these
ash-constituents. It is therefore evident that if all fertile
soils are inexhaustible in mineral matters, it is only the

128 THEORETICAL AND PRACTICAL AGRICULTURE.

unproductive which require a supply of these substances
in order to become productive, and a renewal of the wasted
portion in order to remain fertile.

If an ignorant peasant, who has for thirty years seer
crops follow the ploughing and sowing of his land, who
knows that his father and grandfather had also reaped for
thirty years from the same land after ploughing and sow-
ing, believes himself entitled from these facts to conclude
that this same land will still yield crops for thirty, sixty, a
hundred years, or for an indefinite period, we must hold
him excused on account of his ignorance. But when this
peasant acknowledges that his grandfather, father, and he
himself, have been obliged to manure this land each year,
and then asserts that his field has never received ash-
constituents in the manure, or that the ash-constituents it
received have produced no effect upon the crops, and that
their supply has consequently been of no advantage, we
turn from him with pity. |

If the peasant had been capable of making a correct
observation, he would probably have perceived that his
manure heap constantly diminished in activity, and that
his grandfather with very little manure obtained much
larger corn crops than he now does with all his manure;
he would further have observed that he has now been
obliged to include in his rotation plants which were not
required by his grandfather, in order to maintain the pro-
ductiveness of his fields for corn crops.

We have believed that the object the agriculturist had in
view was the production of grain and flesh, and that the
thoughts of the guides and teachers of practical hus-
bandry had been directed to ascertain the best means of
maintaining the grain and pasture fields in a uniform
condition of fertility. We are now taught better by the
writings of our modern teachers of agriculture: the pro-

THEORETICAL AND PRACTICAL AGRICULTURE. 129

duction of flesh and grain is subordinate to that of form-
yard manure.

For cereals, the soil, they tell us, is always fertile if there
be only enough of manure. “Above all things let us have
fodder enough; the cereals will then follow of themselves.”
“Science does not teach agriculturists much when she tries
to teach them to force nature,” “when she tries to make
them do without farm-yard manure.” (W.S., 127.) “From
the necessity for the rotation of crops agriculture does not
wish to be emancipated, for farmers could even now free
themselves partly from it if they could only manure more
largely.” (W.S., 129.) “Most agriculturists would un-
doubtedly much rather never cultivate anything but wheat
and rapes; but this would never do, for the soil must have
its farm-yard manure, and without a proper rotation farm-
yard manure cannot be made.” (W.S., 129.) “ Farm-yard
manure may be termed the raw material, which agricul-
tural industry is to convert into marketable articles.” (W.
S., 124.) “A rich soil is consequently one which produces
much manure, and a poor soil one which produces little.
Hence, therefore, the division of plants into manure-econo-
musing, manure-exhausting, and manure-enriching plants.
Now, as clover and lucerne are the real manure-producing
plants, and manure is the soul of agriculture, everything
depends upon them.”

Our practical teachers have reduced, as we see, the most
difficult of all trades, which manufactures its products with
the most complicated of all machines—organised beings—
and the pursuit of which is dependent on influences over
which human power has no control, toa most simple fan-
damental principle, intelligible to the most stupid peasant-
boy, viz., the production of manure by fodder plants.

To what results then has this excellent teaching, this out-
cry after manure, led? Clearly and distinctly may the

G*

130 THEORETICAL AND PRACTICAL AGRICULTURE.

present condition of our fields be recognised by the follow-
ing entreaty and appeal to our sympathy and compassion :

“ Were science only to give us the means to enable us to cul-
tivate these plants (clover, lucerne, esparsetie) upon the same
ground with uniform success, more frequently than rs the case
with our present system, then indeed would the philosopher's
stone be found for agriculture ; for as to the conversion of these
plants into the forms adapted to the wants of man, we would
look to that.” (W.S%., 127.)

This, then, is the result of the doctrine of these wise,
clear-sighted, and skilful men, who assert that fertile soils
are inexhaustible in the mineral food of plants.

To procure farm-yard manure, science is good enough ;
they wish to learn nothing from it, but only to obtain a
small piece of the philosopher’s stone. Then these expe-
rienced individuals, who are crammed full of so much in-
formation in chemistry, geology, botany, &c., will procure
us flesh and bread in abundance: this every simple peasant
can do if we only give him manure. Hence, little ‘Japhet
in search of his Father,” the poor child called ‘ Mineral
Theory,’ was so ill-used and ridiculed, because he was of
opinion that the big purse would at last be emptied, by
always taking out money without putting any in. But who
could have thought twenty years ago, when there was
plenty of manure, that it would ever occur to these obsti-
nate and wilful fodder plants to produce no more manure,
and no longer to spare and enrich the ground? ‘The soil is
naturally not the cause of this; for they teach that it is
inexhaustible, and those who have still manure enough
believe that the source from which it is derived will always
flow. ‘Truly, if this soil could cry out like a cow or a horse
which was tormented to give the maximum quantity of milk
or work with the smallest expenditure of fodder, the earth
would become to these agriculturists more intolerable than

THEORETICAL AND PRACTICAL AGRICULTURE. 1381

Dante’s infernal regions. Hence, the advantageous prose-
cution of this system of modern agriculture is only possible
on large estates, for the spoliation of a small one would
soon come to an end. Instead of stealing the leather, if
they had bred the calf, it would have grown to an ox, and
then we should have been saved from the fear of going
barefooted at last.

But we need not yet despair: These wise, prudent, and
experienced men have found out the means of putting an
end to the deficiency of manure. These means, they tell
us, consist simply in making use of /resh, instead of rotted
farm-yard manure. If short-sighted, careless agriculturists,
who do yet not follow this plan, would only put it in practice,
many of the complaints about deficiency of manure would
cease.

“ Notwithstanding the general outcry about want of manure,
and all the trouble taken to increase vegetation ; notwith-
standing the great cultivation of fodder plants to produce
farm-yard manure, it is allowed, nevertheless, when made,
to go to waste on the dung-hill. We may assume that in our
system of farming, the manure is carted out on an average
at most half-rotted. Before the manure arrives at this state,
it loses 25 per cent. of its mass, consisting chiefly of precious
nitrogen ; I will here, however, estimate the loss to be equal in
value to what is left. If all agriculturists would employ
their manure as fresh as possible, so that at most no more
than 5 per cent. be lost, the increase of our cultivated plants
would amount to 20 per cent. Not only would this 20 per
cent. of the whole food employed in increasing the crop be
converted into vegetable matter, but by its means a further
quantity would also be drawn from the air and the soil.”
(S. 181.)

“An increase of the production of fodder is, however,
not required, so long as we do not wish to augment vegeta

132 THEORETICAL AND PRACTICAL AGRICULTURE

tion still more. Hence, the 20 per cent. of dung capital,
could be solely expended on the greater production of grain,
which would thus become so much larger, in comparison
with that of cattle, which remains the same. The supply
of grain would consequently be greater, its price more
moderate, and this would put itself more in equilibrium
with the production of cattle: producers and consumers
would be equally benefited. But greater advantages would
also be attained ; for, instead of expending upon the growth
of corn the 20 per cent. of manure saved, agriculturists
could also diminish their cultivation of fodder by 20 per
cent. The production of corn remaining the same, that of
cattle would be decreased 20 per cent., and hence the latter
would rise in price, whilst that of corn continues the same.
Were the 20 per cent. of manure saved, chiefly devoted to
the growth of corn, and to a smaller extent to that of fod-
der, producers and consumers would derive benefit from
this plan ; only on the part of the former it would be greater,
and at how small a cost—all by means of the 20 per cent. of
volatile matter which careless agriculturists lose by the neglect of
the manure on their dunghills.” (8S. 182.)

Had there been any doubt on the point, this proposition
would incontestably prove that the modern teacher of
practical agriculture puts not the slightest value on the
mineral constituents of stable-dung, but ascribes its entire
effect to the combustible matters it contains. With the 20
per cent. of these matters, which fresh farm-yard manure
loses by rotting, the practical man would make us believe
that 20 per cent. more corn, clover, or flesh could be
produced.

Because, straw manure had accidentally improved the
physical quality of his land, and consequently exerted a
more favourable action than short rotted manure, he teaches,
in opposition to thousands of well established facts, that

THEORETICAL AND PRACTICAL AGRICULTURE. 183

fresh manure must produce larger crops on all fields. He
would make us believe, that when we simply take away
the grain from our fields and plough in the straw, their fer-
tility in each succeeding year must receive an additional
increase equivalent in amount to what the straw loses, when
it has been used as litter, and conyerted into manure!

Now, what is the cause of this great effect of fresh farm-
yard manure, and its advantage over that which is well
rotted? This, also, the man of practice tells us: “‘ Jn fresh
manure there is more nitrogen than in old; the latter, on the
other hand, contains more ash constituents.” (W. S. 101.)
Hence, fresh manure is more efficacious than old! Chemi-
cal analysis, indeed, proves, that rotted farm-yard manure
contains more nitrogen than fresh, but in such matters
practice must decide; and since, according to its teaching,
the larger crops could only have been the result of the greater
supply of nitrogen, it follows that chemical analysis must
be in error.

But, after all, the additional 20 per cent. of manure
which the land of our experienced teacher of practical
agriculture obtains, appears to him far from sufficient,
for he says: ‘‘ Now, since straw and fodder, the materials
for manure, are expensive, and manure must be had at
almost any price, and the latter comes tolerably dear in
consequence of the low price of cattle produce, agricultu-
rists have naturally been seeking for a long time back for
a substitute for manure. Such a substitute has been lately
found in Guano.”

Now, what is guano, and in what way is its employment
advantageous to the agricuiturist ?

Guano consists of the residue of the excrement of fish,
that is, flesh eating birds, and contains essentially the ash
constituents of the flesh of fish, together with a certain
quantity of ammonia salts.

184 THEORETICAL AND PRACTICAL AGRICULTURE.

Comparison shows that the better sorts of guano contain
the ash constituents of grain, together with a certain quan-
tity of phosphate of lime, which forms an essential element
of the ash of our meadow and pasture plants. The effect
of guano on our corn fields is therefore palpable. We
have for hundreds of years removed from them, by the
cultivation of corn, the ash constituents of grain, and by
rearing cattle, we have also taken away a large quantity
of phosphate of lime (in their bones) without replacing any
of these matters; we have, however, left them the condi-
tions for producing straw.

The increase of the produce of grain, by manuring with
guano, is the natural consequence of the restoration of the
elements of grain, which we have been at so much pains to
drag from our fields. The astonishment of the corn pro-
ducer at the powerful effect of guano, after all, arises from
the fact that he sees a few handfuls of this substance act-
ing more efficaciously than a cart-load of stable-dung; and
because in looking at the smallness of the quantity of
the guano, and comparing it with the large increase of grain,
his ideas about manure are completely confounded.

To our experienced teacher of practical agriculture,
guano is, as a matter of course, only a means for producing
manure. Guano, in an agricultural sense, is a ‘supple-
mental manure,” which we ought to use so long as the
supply lasts, for the purpose of increasing our dung capital.
(W. 5S. 187.)

That the effect of guano depends on the volatile and
combustible materials it contains, cannot, of course, admit
of a question; let us hear what would be the result of its
employment.

“The general use of guano can only be attended with a
result similar to that which would take place if the 20
per cent. of manure hitherto lost from the dunghills were

THEORETICAL AND PRACTICAL AGRICULTURE. 185

in future to be made use of.” ‘Those agriculturists who
still allow their manure to rot, hence clearly act foolishly
in buying guano before they derive the fullest advantage
from their own manure.” (W.S. 136.) No value what-
ever is put on the ash constituents of the guano.

The ideas of our teacher of practical agriculture of the
comportment of a soil under cultivation are not less
peculiar. —

“ Notwithstanding that plants are yearly reaped an equal
quantity can, on an average, be continuously removed every
year from the soil (for example, from an unmanured mea-
dow). This is the natural production of the soil. The soil
remains, and continues to remain at a fixed agricultural point
of production. (S. 103.)

“If during a period of one or more years the plants
which grow upon a soil die, and decay, an accumulation
of decaying and decomposing products will thus be gradu-
ally formed in it. There is thus furnished a further source
of both kinds of food, and the development of plants is con-
sequently promoted.” (S. 104.)

‘“ By further new and increased crops more ash constitu-
ents than formerly, as well as products of decay, will be
removed from the soil.”

‘“ After a series of years, and a corresponding number ~
of crops, the ground sinks again to its original degree of
fertility—its fixed point of production. Jt has again at-
tamed its original composition, and as nothing else has been
changed, this alteration of the soil must be the probable cause
of us increased and again diminished fertility.”

‘‘ Stable-manure consists of decaying vegetable and ani-
mal matter, which also contains a certain quantity of ash
constituents, hence the development of plants can be as
well promoted by stable-manure as by plants which decay
upon the fields themselves.”

136 THEORETICAL AND PRACTICAL AGRICULTURE.

From these propositions which are given as agricultural
principles, it would follow that our cultivated fields com-
port themselves like unmanured meadows. Whether we
cultivate grain, turnips, or clover, on one and the same
field, we may fairly expect continuously, and without any
application of manure, an average yearly crop of the same
amount. This would be the natural production, or the
agricultural fixed point of the soil!

If we leave meadow plants, corn, and clover, to die and
decay on the field, manure accumulates in the soil and ren-
ders it more fertile. We obtain larger crops, and withdraw
by these means more ash constituents than before, in consequence
of which the ground becomes poorer.

Having followed this course for some years, the ground,
robbed of its ash constituents, sinks back to its fixed point
of production. It has again attained its original composi-
tion (that is, 7 contains no more combustible matters than at
first), and since nothing further has been changed (as everything
depends upon this), then this alteration of the soil—the dimi-
nution and increase of combustible matters in t—must._ be the
probable cause of its increased and again diminished fer-
tility.

The views cited above are those of a single man, but
with few exceptions belong to the whole class of practical
acriculturists. What the author teaches is not an invention
of his own, but he retails what he has learned. I have
reviewed these doctrines, not for the purpose of exercising
indiscriminate criticism, but because, without holding up to
view the opinions of practical men, my own peculiar doc-
trines might appear to many in the present day incompre-
hensible, and perhaps, at no distant date, vain and object-
less.

I need not add one word more; the passages just cited
give the key to the conflict which has been raised about

THEORETICAL AND PRACTICAL AGRICULTURE. 187

the recognition and application of scientific principles in
practice ; that the latter do not enter into the circle of ideas
of practical agriculturists will now be easily understood.

Many agriculturists are of opinion that in this contest it
is a question of words, not of principles, and that an
understanding is possible. They think that if they allowed
the action of mineral substances, then, in justice, the other
party will acknowledge that of combustible substances, and
thus the conflict would come to a happy termination. If
the contest for the recognition of scientific principles had
in fact no higher object than the admission into broth of
onions previously forbidden, or the compromise that eggs
may be opened at both ends, then they are right.

They are right so long as they entertain the opinion that
the best master brewer of the best Bavarian beer is the fit-
test man for a chair of brewing.* I, for my part, do not
believe that such a man should be recommended as the
proper person for imparting the scientific principles of
brewing, even though he had for twenty years conducted
the most extensive business of this kind with skill and
profit.

* This sentence refers to the arrangement of many German agricultural
institutions, They are in general endowed with a considerable extent of
land, which is managed like other government lands. The produce of the
soil finds its way into the public coffers. The school and the land are united
with each other in the person of the Director, to whom is intrusted the cul-
tivation of the ground and the superintendence of the instruction; in the
net proceeds of the farm he has commonly a share. There are men who are
endowed with capabilities for both offices, but it usually happens that a good
practical man is not the best instructor, and the latter is not generally an
individual who sets much value on obtaining great profits from the land.

LETTER X.

The empirical agriculturist is a trader—The duties of the empirical and
rational agriculturist— Views of Albrecht Block—Rotation of crops not un-
important; an underground crop is followed by a better cereal—Cropping
of land without manure, and the removal of produce, cause exhaustion—
The spoliation system of agriculture—Exhaustion of the lands in North
America by this system—Exhaustion of the Minas Geraes fields—High
farming is a more subtle system of spoliation of the soil—Mutual relation
of clover, turnip, and corn crops; and the results of removing from the
lands the mineral constituents of these crops respectively—The German
system of farming before the Thirty Years’ War—The German three-field
system of rotation—Introduction of clover cultivation into Germany—
Opposition to its introduction—False teaching in connection with the value
of manures.

THE empirical agriculturist is a trader who produces
meat and corn; without troubling his mind about collateral
matters, he simply seeks to gain from his fields the largest
possible crops, and he holds that system of cultivation as
the best which will yield him the richest harvest in the
cheapest way, and in the shortest time. And why should
he not? The same system of husbandry which he pursues
has been followed for centuries before his time, and he sim-
ply practises the lessons taught him by those who preceded
him in the farming of his land. As they never inquired
what might ultimately become of the land, and what effect
their system of cultivation might have upon it—why should
he trouble his mind about it? If he can succeed in making
a living out of his farm, clearing his rent, or the interest
on his capital, and acquiring some property besides, this
alone is proof positive of the soundness of the system.

THEORETICAL AND PRACTICAL AGRICULTURE. 189

When he happens to remark a falling off in his wleat,
clover, turnip, or potato-crops, he tries whether growing
some other varieties on his fields will answer better, and
attributes the diminished fertility of the soil to any and
every event that may have occurred since he first remarked
the decrease. Thus he will complain that his fields no
longer yield the rich crops of former years, ever since the
adjoining wood has been cleared; or ever since the railway
was made; or the chemical manufactory established in the
neighbourhood ; or he will attribute the falling off to the
injurious influence of the numerous thunderstorms in the
preceding year; or to any other imaginable or imaginary
cause—except always to himself and his system ; the wea that
the fault might possibly lie with him or his system can find no
place in his mind; for, has he not pursued the same system
for years with the very best results; his dungheap is as
large as ever, and the land does not look changed in the
least ?

Asa trader he is in the position of a shoemaker who
must not devote his attention to investigations into the
origin of sole and other varieties of leather, the process of
tanning, and the properties which constitute the good qua-
lity of the article, and who, were he to do so, would most
likely supply the public with boots and shoes, neither cheap
nor overwell made. The true shoemaker who thoroughly
understands his craft, does not trouble his mind about such
matters; he leaves to others, whose special business it is,
the task of studying them; if he happens to be a man of
some education, he studies the anatomy of the foot, and
makes shoes that shall delight the female eye, and boots
that shall not distort the shape of the foot, nor pro-
duce corns. Such a pearl of a shoemaker would never
dream of disputing with the man of science about leather,
pitch, and thread, as he would have no time for such dis-

140 THEORETICAL AND PRACTICAL AGRICULTURE.

cussions; he would, on the contrary, be grateful to the che-
mist for teaching him how and by what marks or signs to
know and select the sorts of leather for soles and uppers
best suited for the purposes for which they are severally
intended.

The scientific farmer and teacher of husbandry has a
higher task assigned him. It is for him to rise above the
mere routine teachings of empiric observations; to guide
and keep the practice of farming in the right path; to sub-
ject to a rigorous and searching investigation the methods
of husbandry adopted and pursued by the empirical farmer,
in order to point out to him the why and wherefore, and
to lead him to a proper sense and rational appreciation
of his doings, and their results and consequences. The
rational agriculturist has to inquire whether his system ac-
cords with established truths and natural laws, or is in
opposition to them; and above all, he must never lose
sight of the one great principle, that the aim of true prac-
tical husbandry must be directed, not merely to the pre-
sent production of the largest crops, but to the securing of
a constant return of such crops.

If the teacher of husbandry, instead of assisting and sup-
plementing in this way the practice of agriculture, indulges
in views that are simply calculated to vindicate the farmer
in his empirical proceedings ;—if, whilst clearly seeing that
this empirical system of husbandry is opposed to established
natural laws, he draws therefrom the conclusion that these
natural laws may possibly not apply to practical farming,
and that agriculture accordingly may not be subject to
natural laws ;—if he asserts that the practice of husbandry
and the science of agriculture may be treated as separate
and distinct questions, and that a thing may possibly be
true in science that ts false in practice,—if such are the doc-
trines propounded by him, he stands as an agriculturist far

THEORETICAL AND PRACTICAL AGRICULTURE. 141

below the practical farmer, who fails to derive instruction
from these lessons, simply because he finds in them nothing
but a reflex of his own doings in the cultivation of his land,
garnished with misconceptions and false views.

A simple comprehensive natural law governs the greater
or less abundance, and the longer or shorter succession and
continuance of the crops that can be grown on a field.
The greater or less abundance of the yield of a field de-
pends upon the aggregate sum of the conditions of fertility
therein existing; the longer or shorter continuance and suc-
cession of the crops that may be grown thereon, depend
upon the unaltered condition of this aggregate sum.

A practical agriculturist, Albrecht Block, is reported to
have said: “A farmer can afford to sell and permanently
alienate only that portion of the produce of his farm which
has been supplied by the atmosphere—a field from which no-
thing ws abstracted can only increase, not decrease in productive
power.” If we express the same idea in another form, viz.,
“A farmer may sell and permanently alienate all that portion
of the produce of his farm which has been supplied by the
atmosphere—a field from which something is permanently
taken away, cannot possibly increase or even continue equal in
productive power,” the axiom thus enunciated is simply a
natural law. In this opinion of this truly experienced man,
to whom future agriculture will surely raise a monument,
is at once expressed the whole foundation and groundwork
of rational farming, and all the knowledge that the science
of nature can teach the practical farmer.

Every act of the farmer which violates the laws of na-
ture, must justly be branded as an act of spoliation.

If a farmer grows in three several fields alternately pota-
toes, corn, and vetches or clover, or on one and the same
field successively potatoes, corn, and vetches, and sells the
produce obtained—the corn, the potatoes, and the vetches,

142 THEORETICAL AND PRACTICAL AGRICULTURE.

and continues to act in this manner for many years, without
manuring his land, the humblest peasant will predict the
inevitable end of such a system; he will tell him that a
continuance of this kind of farming is impossible for any
length of time. Whatever grass, corn, tuber, or other crop
may be selected, and in whatsoever rotation,—the field will
ultimately be brought to a state of exhaustion by it; the
corn will only yield an amount equal to the original seed,
the potatoes will no longer produce tubers, and the vetches
or the clover will die away after barely appearing above
ground.

These facts undeniably demonstrate that there exists no
plant that could possibly be said to husband the resources of
the soil, and @ fortiorz, none that can possibly be had to
enrich it.

Innumerable facts have taught the practical farmer, that,
in many cases, the successful cultivation of an after-crop on
a field depends upon the nature of the preceding crop, and
that it is by no means a matter of indifference in what suc-
cession or rotation he grows his crops. The previous cul-
tivation of some underground crop, or some plant with
extensive root ramifications, will tend to make the soil
more favourable for the subsequent growth of a cereal.
The latter will in such cases thrive better, and it will do
so without the use (with the sparing application) of manure,
and will yield a more abundant crop. But as regards
succeeding harvests, there has been in reality no saving of
manure, nor has the field zncreased in the conditions of its
fertility. There has been no augmentation in the gross
amount of the elements of food in the soil, but simply an
increase of the available effective portion of these elements,
and an acceleration of the results in a given time.

The physical and chemical condition of the fields has
been improved, but the chemical store has been reduced ;

THEORETICAL AND PRACTICAL AGRICULTURE. 1438

all plants, without exception, exhaust the soil, each of them in
as own way, of the conditions for their reproduction.

There are fields that will yield without manuring for six,
twelve, fifty, or a hundred years successively, crops of
cereals, potatoes, vetches, clover, or any other plants, and
the whole produce can be carried away from the land; but
the inevitable result is at last the same, the soil loses its
fertility.

In the produce of his field, the farmer sells-in reality his
land; he sells in his crops certain elements of the atmo-
sphere that are constantly being replaced from that inex-
haustible store, and certain constituents of the soil that are
his property, and which have served to form, out of the
atmospheric elements, the body of the plant, of which they
themselves also constitute component parts. In altogether
alienating the crops of his fields, he deprives the land of
the conditions for their reproduction. A system of farm-
ing, based upon such principles, justly deserves to be
branded as a system of spoliation. Had all the constituents
of the soil, carried off from the field in the produce sold,
been, year after year, or rotation after rotation, completely
restored to the land, the latter would have preserved its
fertility, to the fullest extent; the gain of the farmer would,
indeed, have been reduced by the re-purchase of the alien-
ated constituents of the soil, but it would thereby have
been rendered permanent.

The constituents of the soil are the farmer’s capital; the
elements of food supplied by the atmosphere, the interest
of this capital: by means of the former, he produces the
latter. In selling the produce of his farm, he alienates a
portion of his capital and the interest; in returning to the
land the constituents of the soil removed in the crops, he
simply restores his capital to his field.

Every system of farming based on the spoliation of the

144 THEORETICAL AND PRACTICAL AGRICULTURE.

land leads to poverty. The country in Europe which, in
its time, most abounded in gold and silver, was, neverthe-
less, the poorest. All the treasures of Mexico and Peru
brought to Spain by the richly laden silver fleets, melted
away in the hands of the nation, because the Spaniards had
forgotten, or no longer practised, the art of making the
money return to them, which they had put into circulation
im commerce to supply their wants; because they did not
know how to produce articles of exchange required by
other nations, who were in possession of their money.
There is no other way of maintaining the wealth of a nation.

It is not the land in itself that constitutes the farmer’s
wealth, but it is in the constituents of the soil, which serve
for the nutrition of plants, that this wealth truly consists.
By means of these constituents alone, he is enabled to pro-
duce the conditions indispensable to man for the preserva-
tion of the temperature of his body, and of his ability to
work. Rational Agriculture, in contradistinction to the
spoliation system of farming, is based upon the principle
of restitution ; by giving back to his fields the conditions of
their fertility, the farmer insures the permanence of the
latter.

The deplorable effects of the spoliation system of farming
are nowhere more strikingly evident than in America; where
the early colonists in Canada, in the State of New York, in
Pennsylvania, Virginia, Maryland, &c., found tracts of
land, which for many years, by simply ploughing and sow-
ing, yielded a succession of abundant wheat and tobacco
harvests; no falling off in the weight or quality of the
crops, reminded the farmer of the necessity of restoring to
the land the constituents of the soil carried away in the
produce.*

* New York.—In the debate on the Bill passed by the Lower House of

THEORETICAL AND PRACTICAL AGRICULTURE. 145

We all know what has become of these fields. In less
than two generations, though originally so teeming with

Congress, by which a grant of six million acres of Union land is made to the
several States, for the establishment and maintenance of agricultural and in-
dustrial schools, the mover of the Bill, Mr. Morrill, of Vermont, showed, in a
most excellent speech, by means of exact statistical returns, how urgently
these schools are required for the better education of our fee who at
present, it would appear, are guilty of the grossest Vandalism in the manage-
ment of their land. The speaker showed that we in America are far behind
Europe in agriculture in general, and more especially in the modern scientific
system of farming; and that the sad results of this state of things are even
now becoming manifest to an alarming extent. The honourable gentleman
said, the general method of husbandry pursued in all parts of the Union was
so bad and imperfect, that it must necessarily year after year more and more
impoverish the soil; and the incessant drain on the natural productive power
of the soil amounted simply to downright robbery, committed by individuals
at the expense of the national property.

The following table in some measure shows the falling off that has taken
place within a period of ten years in the annual yield of agricultural produce
in several of the Northern States. The number of bushels of wheat produced
was in

1840 1850
Connecticut . : : : . - 87,000 41,000
Massachusetts . ° . 3 q » 157,923 31,211
Rhode Island . ° . . é P 3,098 49
New Hampshire. ‘ . : - 422,124 185,658
Maine “ ° F . . Y - 848,166 269,259

Vermont . . : . ! : - 495,800 535,955

Somisil ., 3.2,014,911 1063 192

‘ Potatoes.
Pannen ek wv tS aI 2,689,805
Massachusetts a . : . . 6,385,652 3,385,384
Rhode Island Praha) Viable, fats eae Se 651,029
New Hampshire . , 5 : . 6,206,606 4,304,919
Maine ; » . ‘ - 10,392,280 3,436,040
Vermont ... Pepa ee ey 4,951,014

ee ee a eee

Sumtotal . . . 35,207,500 19,418,19

146 THEORETICAL AND PRACTICAL AGRICULTURE.

fertility, they were turned into deserts, and in many dis:
tricts brought to a state of such absolute exhaustion, that

In many Southern States this falling off in the produce of the soil is equally
significant. The number of bushels of wheat produced was in

1840 1850
Tennessee . - : . 4 . 4,569,692 1,616,386
Kentucky . : . i . . 4,803,162 2,142,822
Georgia . : . : . 1,801,830 , 1,088,534
Alabama . : 3 ; ; - 838,052 294,044
Sum total . ; . 12,012,736 6,141,786

These figures show pretty conclusively that in all parts of the Union the
land must have been deprived of some of its most essential elements, and that its
fertility is constantly on the decrease. In the State of New York there are
now 300,000 sheep fewer than thirty years ago. Within a period of five
years the decrease in the number of sheep in the State of New York
amounted actually to nearly 50 per cent., and in the number of horses,
cows, and swine to above 15 per cent. In 1845 the wheat crop in the State
of New York amounted to 13,391,770 bushels; it has since then fallen off
year after year, and last year it actually did not exceed 6,000,000 bushels.

The average produce of Indian corn was in 1844, 24°75 per acre, in 1854
it was only 21°02. The average yield of wheat was in Virginia and North
Carolina, in the year 1850, no more than seven bushels per acre, and in Ala-
bama five bushels. While the cotton crops in the new territories of Texas
and Arkansas yield annually an average produce of 700 to 750 lbs. per acre,
the old fields of South Carolina produce only half as much. The tobacco
crop of Virginia was 18 million lbs. less in 1850 than in 1840. No kind of
crop has proved so injurious to the fertility of the soil as that of tobacco, and
in many of the States whole tracts of land are now lying waste, that for a
century had been made to yield, year after year, crops of tobacco, maize, and
wheat. There can be no doubt but that three-fourths of the arable soil of
the Union are undergoing, to a greater or less degree, this exhaustive pro-
cess. Dr. Lee, of Georgia, estimates the decrease in the annual produce of
the soil of 100 million acres of land in the United States, at ten cents per
acre. This would give a total of 10,000,000 dollars, making the amount lost
equal to a capital of 166,666,666 dollars—a larger sum than all our federal
and states taxes together.

In other branches of husbandry also enormous losses are caused by the
want of proper information on many essential points—a want which can only
be remedied by the establishment of agricultural schools. One of the ablest

THEORETICAL AND PRACTICAL AGRICULTURE. 147

even now, after having lain fallow more than a hundred
years, they will not yield a remunerative crop of a cereal
plant.

As every agriculturist in Kurope has a notion that his
system is an exception and better than that of others, and
that, judging from his own experience, his fertile fields require
no restoration of mineral matters to keep them up to the
proper degree of productive power, so every early colonist
also believes at first that his land, for the crop which he
grows on it, forms an exception to other fields. He also
trusts to his experience to insure an infinite succession of
rich harvests; but even ere his children are grown up, he
finds out his mistake. His farm passes into the hands of
another colonist, who continues to despoil the soil in the
same way as his predecessor, only with a larger expenditure
of capital and labour. When he, in his turn, perceives that
the plough will no longer suffice to keep the yield up to the
former height, the land is then finally handed over to the
tender mercies of the German colonist, who has been taught
to look upon dung as the soul of agriculture,—a maxim of
specious wisdom, of which his predecessor knew nothing,
and the new owner then sets about despoiling the soil after
his own fashion.*

agriculturists in Massachusetts estimates the annual loss to the States, in
cattle of all kinds, and in the produce of the dairy, &c., at several millions.
There are about 447,014 horses in the State of New York, on which, from
the prevailing ignorance of the veterinary art, there is an annual loss of not
less than two million dollars.

These statistics could not, of course, fail to produce the impression intended,
and the House gladly entertained the motion to establish agricultural and
industrial schools. It would be a pity ifthe Senate should not be able to find
time before the approaching adjournment to discuss and adopt the measure.
—Allgemeine Zeitung, No. 175. Supplement of June 24, 1858.

_ %* “ Agriculture, in so far as I had occasion to inquire into the matter, is in
a most primitive and unsatisfactory state in the province of Minas Geraes. It
consists simply of a system of downright spoliation, disproportionately large

148 THEORETICAL AND PRACTICAL AGRICULTURE.

The European system of cultivation, called high farming,
is not that open system of robbery of the American farmer,
followed by the utter exhaustion of the soil; but it is a more
refined species of spoliation, which at first glance does not
look like robbery. It is spoliation accompanied by self-
deception, veiled under a system of teaching, the very basis
of which is erroneous.

The simplest peasant has sense enough to see, and all

quantities of the mineral constituents being constantly taken off, without the
restoration of any portion whatever. Thus, for instance, they make a so-called
Roca, %. €., the trees and underwood are cut down on a certain tract, and
towards the end of the dry season burnt on the spot; three or four harvests
are then taken from the land so prepared, and it very often occurs that among
these there are two Indian-corn crops in immediate succession. After this
the field is allowed to lie fallow until it is again sufficiently covered with
brushwood, when the same process is repeated; the interval varying between
three and twelve years, according to local conditions and to the wants of the
proprietor. It is quite evident, that the soil here has never had restored to it
the smallest portion of the mineral constituents removed by the crops. No
wonder, then, that there should be universal complaints in the province of the
constantly increasing sterility of the Rocas. One of the more intelligent
planters of the province told me that, of all the plants grown there none
showed so large a falling off as the sugar cane, and that he at present reaped,
on the same Rocas, only a third of the produce obtained by his father 55 to: 60
years ago; and yet, he remarked, somewhat naively, he was much better off
with his small crop, than his father had been with the larger one, for the
latter (his father) had barely been able to realise a milreis for the cask of
Cachaza (brandy), whereas he himself had last year received 14 milreis for the
same. Now this man was perhaps right in his way; but how will it fare
hereafter with his son, if he continues the same system, and the price of
Cachaza happen to fall again? In the province of Bahia, the falling off in
the sugar-cane crops is so great, that about a twelve month since a number of
planters combined to send out a ship to bring from several distant ports new
sorts of sugar-cane. They attributed the falling off in the produce of their
plantations simply and solely to the degeneration of the cane, without reflect-
ing that by the incessant cultivation of the plant on a large scale, their land
had been most enormously drained of the conditions of its fertility.” —J. J. von
Tschudi’s Journey through the Province of Minas Geraes.—Allgemeine Zeitung,
No. 47, May 27, 1858. Supplement.

THEORETICAL AND PRACTICAL AGRICULTURE. 149

agriculturists agree with him, that clover, turnips, hay, &c.,
cannot be sold off from a farm, without most materially
damaging the cultivation of corn. Every one willingly
admits that the sale and exportation of clover, turnips, &c.,
exercise a detrimental influence on the growing of corn.
“ Above all, let us take care to have plenty of fodder, the
corn crop will then take care of itself.” But that the eapor-
tation of corn may possibly exercise an injurious influence on
the cultivation of clover or turnips, that it is above all
indispensable to restore to the soil the mineral constituents
of the corn, to enable the clover or turnip crop in its turn to
“take care of itself,”—in other words, that in order to grow
clover, turnips, &c., we must manure the land—this is a
notion utterly incomprehensible, nay absolutely impossible,
for most agriculturists. For, is not the clover grown for
the sake of the manure? What advantage, then, would
there be if it were necessary to manure again to produce the
clover? This clover the farmer expects to grow for nothing.
From this total misapprehension of the very foundation of
all true industry, spring all the errors and defects of the
prevailing system of cultivation.
The mutual relations existing in the order of nature
between the two classes of plants, are, however, as clear as
daylight. The mineral constituents of the clover, turnips,
&c., and of the corn, form the conditions for the production
of the clover, turnips, &c., and of the corn, and they are in
their elements quite identical. The clover, turnips, Xc.,
require for their growth a certain amount of phosphoric
acid, potash, lime, magnesia—so does the corn. The mineral
constituents contained in the clover are the same as those in
the corn, plus a certain excess of potash, lime, and sulphuric
acid. The clover draws these constituents from the soil ;
the cereal plant receives them—we may so represent it—
from the clover. In selling his clover, therefore, the farmer

150 THEORETICAL AND PRACTICAL AGRICULTURE.

removes from his land the conditions for the production of
corn; no mineral constituents are left for the corn. If, on
the other hand, he sells his corn, there will be no clover crop
in the following year; for in his corn he has sold some of
the most essential conditions for the production of a clover
crop.

The peasant expresses in his own way the part which the
cultivation of clover and other fodder plants performs in
the economy of his land, when he tells us that he regards,
as a self-evident proposition, that a farmer must not sell
his stable manure; that without manure a continued culti-
vation of his farm is impossible; and that a farmer who
sells his clover and other fodder plants, does actually sell
his manure, and that there is no need of the wisdom of the
chemist to make him understand this. This is very true;
for so far as that goes, the common sense of the simplest
peasant will guide him. But that a farmer, in selling his
corn, is still actually parting with his manure, would, how-
ever, appear to be beyond the comprehension of the great
majority of the most enlightened agriculturists. The dung
contains all the mineral constituents of the clover and
-other fodder plants, and these consist simply of the mineral
constituents of the corn, plus a certain quantity of potash,
lime, and sulphuric acid. Now, as the whole dung-heap
consists of parts, it is quite evident that the farmer must
not sell any part thereof; and that, if it were possible to
devise a means of separating the mineral constituents of
the corn from the others, those very mineral constituents
so separated would have the very highest value for the
farmer, as they form the most essential condition for the
production of corn. Now, in the cultivation of corn this
separation is actually effected, for these mineral constitu-
ents of the manure are converted into constituents of corn.
In selling the corn produce of his fields the farmer parts,

THEORETICAL AND PRACTICAL AGRICULTURE. 151

therefore, with a portion, and, indeec, with the most effi-
cient portion of his manure.

Two dung-heaps of equal appearance, and seemingly
equal quality, may have a very dissimilar value for the
cultivation of corn; if one of the heaps contain twice as
much mineral constituents of corn as the other, it has
double its value. By the exportation of the mineral con-
stituents of corn, which the latter had drawn from the
manure, the dung of the farm is made to suffer a progres-
sive diminution of its efficiency for future corn crops.

In whatever light, therefore, we may look upon the
exportation of corn, or any other produce of the fields, to
the farmer who omits to restore to the soil the mineral
constituents removed from it, the ultimate result will
always be exhaustion of his land. The continued expor-
tation of corn renders the soil unproductive for clover, or
deprives the dung of its efficacy. Dung, in itself, has an
agricultural value only in so far as it contains the conditions
necessary for the growth of the saleable produce; the mere
size or extent of a dung-heap does not constitute its value.

The reader will now understand what a total want of all
knowledge there is in the precept, that dung is the raw
material to be worked and made into produce by agricultu-
ral industry ; and how essentially that axiom and opinion
have contributed to blind the eyes of agriculturists to the
clear perception of the sole and original source of all
agricultural production, and of their own prosperity—vwiz.,
the soul. :

If our farmers had to till the teeming virgin soil of
America, Australia, or New Zealand, a professor of agri-
culture, who would try to persuade them that ‘‘ manure is
the soul of agriculture,” would simply appear ridiculous in
‘their eyes, as their own experience would show them that
the fields yield rich harvests without manure.

152 THEORETICAL AND PRACTICAL AGRICULTURE.

In our exhausted fields the roots of tne cereal plants
find no longer, in the upper layers of the soil, a sufficiency
of food for a full crop; the farmer, therefore, grows on
these fields clover, turnips, and other plants, which, with
their wide-spreading and deep roots, penetrate through the
soil in all directions, and by the great surface of their roots
render available, and assimilate to themselves, those con-
stituents of the soil which the culmiferous plant requires
for the formation of seed.

In the remains of the roots, stalks, leaves, and tubers of
these plants, which the farmer puts in the form of manure
on the upper layers of his soil, he returns to it in a concen-
trated form the deficient corn constituents required for one
or several full crops. These indispensable elements of
food, which were before scattered throughout the subsoil,
have by the green crops been collected from it and added
to the surface soil. In effecting this object, the clover and
fodder plants can no more be regarded in the lhght of
creating the conditions necessary for the larger corn crops,
than the rag-gatherer, who collects the materials for manu-
facturing paper, can be looked upon as the producer of
those rags.

The American farmer despoils his field without the least
attempt at method in the process.2 When it ceases to yield
him sufficiently abundant crops, he simply quits it, and
with his seeds and plants, betakes himself to a fresh field;
for there is plenty of good land to be had in America;
and it would not be worth his while to work the same field
to absolute exhaustion. But our modern system of “ high
farming” is an organised system of spoliation—the last,
highest, and most finished degree of the art of wearing out
the soil.

Before the thirty years’ war the population of Germany
was not smaller than at present. Every indiyidual naturally

THEORETICAL AND PRACTICAL AGRICULTURE. 1538

required at that time for breathing and working, the same
supply of oxygen and of the elements of muscular force as
people require at present for the same purpose. The agri-
culturist of that day pursuing the same spoliation system as
the American farmer of our day, produced the same supply
of carbonaceous and nitrogenous food as is grown at pre-
sent; only he took more time to do so. There were years of
scarcity, the effects of which were more severely felt then
than they are now, because they were not mitigated at that
time by a supply of the deficiency from America, Hungary,
or the great granary of South Russia; but in ordinary
years the land produced plenty. One year, Winter corn
was grown; the next year, Summer corn and turnips (Stop-
pelriiben); the third, the field was allowed to rest; there
was no other rotation except with pulse. What is now-
a-days called stall-feeding, was entirely unknown. The
meadow suppled winter fodder for horses; cattle and
sheep found their food on the commons or fallows, and in
the woods. The agricultural system of that period might
be likened to the system of the man who had an income of
one florin a day, and who let the florins of one week accu-
mulate in order to spend them in the next week. On
Sunday he found himself accordingly with seven florins in
his pocket, and could therefore now afford to spend on the
Monday following four florins; on Tuesday, three florins;
and on Wednesday, other three florins, and in this manner
was able to buy a number of things which he would have
been unable to procure with a daily expenditure of one
florin.

The system of letting the land lie fallow every third
year did not make the soil more fertile, or add to the ele- |
ments and conditions of its productiveness; but it served |
to render those elements and conditions more available
within a certain time. Except by conveying to it a supply |

7*

154 THEORETICAL AND PRACTICAL AGRICULTURE.

of fertilising material, it is quite impossil Je to make a field
richer and permanently more productive. That the field
did yield a more abundant crop after having lain fallow
was owing simply to the fact that the soil still contained a
sufficient store of effective mineral constituents, only not in
a state available or assimilable for the roots. The rest
enjoyed by the field during fallow afforded time for part
of their store to be made available as food, and in this way
a remunerative crop was obtained. The overplus of the
more abundant harvest which follows a period of fallow, is
not a real addition to the revenue yielded by the field, but
simply a saving from the preceding year, when the land
was at rest. By means of this system the soil is somewhat
more profitably despoiled of its resources, as the work of
spohation proceeds more leisurely. Time, people argued,
costs no money, and fallow saves manure, an advantage
which was clear to all. This system prevailed till towards
the middle of last century. The peasantry, as a body, fell
into a state of poverty and wretchedness, and the production
of the fields continued decreasing.

In the seventeenth and the beginning of the eighteenth
century, the culture of the vine was still flourishing in
countless places in Germany ; fields upon fields were then
occupied by vineyards where the grape now no longer
erows; the large tithe-cellars alone, which still continue
to exist in many places, give evidence of the immense
extent of the vine culture in by-gone days. With the
vineyards the spoliation system of cultivation sooner pro-
duced its results; for vineyards produce no manure, and
as the corn growers found that the cultivation of their own
fields stood in the utmost need of all their manure, the
culture of the vine necessarily died out, like the flame of a
lamp for want of a supply of oil.

‘The only winter-food the farmer had for his cattle,

THEORETICAL AND PRACTICAL AGRICULTURE. 155

besides bad and sour meadow-herbage, consisted of white
turnips, carrots, cabbage and potatoes; and even of these
there was no great store, because the fields had ceased to
produce when unmanured. ‘This scanty food was, through-
out the whole winter, whilst it lasted, made still scantier by
steeping and boiling to eke it out, and when at last it came
to an end, the cattle had to starve on barley, oat and pease
straw. ‘The milk, butter, and cheese yielded in return were
little in quantity and wretched in quality. The coming of
spring was anxiously awaited to get a few cuttings of the
young wheat shoots, and the cattle were sent to the com-
mon to feed on grass barely a couple of inches high, whence
the poor beasts returned at night just as famished as when
they had left the stable in the morning, looking like the
lean kine that Pharaoh saw in his dream.” ‘This is the
description given of the then state of agriculture in Ger-
many by John Christian Schubert, whom the Emperor,
Joseph II., created a Knight of the Holy Roman Empire,
bestowing upon him the style and title of Ritter von
Kleefeld (Knight of Cloverfield), as a mark of imperial
appreciation of the eminent services rendered by him in the
introduction of the cultivation of clover into Germany.
The new culture introduced by the worthy Knight was
hailed with acclamation all over the Empire. The peasants
who grew clover received silver “ clover-dollars,” to wear
round the neck. WStercutius,* the God of Manuring of
Ancient Rome, whose worship had been abandoned for
2000 years, was replaced on his throne: in Agricultural
Educational Institutions altars were raised to him, at which
his priests even to this day continue to sacrifice. But the
God of the Dunghill proved capricious. He seemed to

* Stercutius, or Sterquilinus, according to some, one of the names of
Saturnus. (See Virgil’s “Georgics,” by Voss, page 74.

156 THEORETICAL AND PRACTICAL AGRICULTURE.

make some fields the special objects of his bounty, only to
forsake them again after a time; and now, after a hundred
years’ sway, he has grown altogether stern and unkind.
He no longer bestows his former rich gifts even upon his
most assiduous worshipper, and from the very fields which he
once seemed most to favour, he now withholds the power of
producing the poorest crop of manuring plants. Therefore
do his priests urgently supplicate for a small piece of the
philosopher’s stone to be offered as an oblation to the God
of Manure, that he may relent, and make clover for manur-
ing grow for the future on fields on which that plant will
now no longer thrive. When ata later period the potato
and the application of marl and gypsum to the land came
to aid the beneficial efforts of the cultivation of clover,
people trusted there would now be an end for ever to all
want. The old spoliation system, first in its naked form,
and then altered by the introduction of fallow, now under-
went a further modification, based on the system of a well-
known highwayman on the borders of the Rhine. He
stripped the rich of their dollars, bestowed at times a
penny on the poor, and for sport cut the buttons off their
breeches.

According to his creed the wealth of the rich had been
stolen from the poor, and it was but justice therefore to
make them disgorge it.

Our high farmer acts upon a similar principle. In his
corn crops he makes the (rich) clover disgorge, as it were
the dollars which it has extracted penny by penny from the
(poor) field; and he fancies this system of robbery will last
for ever, as his instructors have taught him that his land
possesses the property of sweating penny pieces.

The consequence of this spoliation system upon the
principle of the noble robber are clear, patent, and obvious
to everybody ; never has the want of manure been more

THEORETICAL AND PRACTICAL AGRICULTURE. 157

severely felt than at present. All the ways and means
which so marvellously tended towards the end of last cen-
tury to increase the productiveness of the land, are at pre
sent resorted to in vain; they fail to produce their former
effect. The application of gypsum to the soil now makes
the clover only more watery, without increasing the crop ;
land treated with marl is more unproductive than before.
Were it not for the manure which the trees of the forest
yield in many countries, the culture of the cereals would,
in many former fertile districts, long since have come to an
end, like that of the vine. The agriculturist in these parts
now despoils the woods, as he formerly despoiled his fields,
and he will continue this new system of depredation as
long as it will answer! “If you will grow clover, and will
strictly follow my directions,” said the good Schubert to the
peasants of his tyme, ‘you will have ample cause for
rejoicing and for praising the Lord out of the fulness of
your heart for his rich blessings. But bear in mind one
rule, which I charge you now once for all to follow; never
grow clover at the expense of corn, but grow it only in
fallow, that it may cost you nothing—in other words, give
up the practice of letting a field lie fallow.” At that time
there was no other system of husbandry known but the so-
called ‘‘ Three-fields-system,” or system of triennial rota-
tion. In twelve years cereals were grown eight times in a
field, and clover four times. Where are those glorious
days when the same field yielded in three years two crops
of corn and one of clover into the bargain! Now-a-days
high farming produces in twelve years only six corn crops.
In Mecklenburgh good land gives only four corn crops in
nine years. The original area on which fodder plants
were cultivated, and which at the time proved amply sufii-
cient to collect and concentrate the food required for the
cereals, is therefore no longer large enough to keep up the

158 THEORETICAL AND PRACTICAL AGRICULTURE.

supply, and it has become necessary to extend it. The cul-
tivation of food for cattle takes up at present as great, and
even a greater breadth of land than the raising of food for
man ; and men’s minds and ideas have become so perverted,
that this lamentable fact is actually looked upon in the
light of a great improvement!

So long as those most interested in the matter, instead
of reflecting upon the conditions on which the successful
cultivation of all plants depends, and. trying to discover
these conditions and to understand their application in
practice, seek to put agriculture into a healthy condition
by ‘“‘ manure,” a thing so very indefinite, indefinable, and
variable in its nature, no real progress can be expected.
For my part, I am quite aware, that science will for a long
time to come have to preach to deaf ears. So long as agri-
culturists derive from the spoliation of their own lands
plentiful crops and a good income, there is no hope of the
advent of a more rational system of husbandry. The field
is to such men, simply a cow that gives them milk, but
which they would feed with its own flesh, taken from its
ribs; and the folly of such a proceeding will strike them
only when the light shines through the hollow skeleton of
their victim. Man is naturally prone to spoliation, and
dreads nothing so much as to have to exert his mental
faculties in the acquisition of what he needs; he is in
many respects like a child in whose eyes the school and
learning are the greatest of all troubles. Necessity is the
only compulsory agent that will ever make him moye, and
this will come soon enough.

The dangers threatening the state and society from the
wanton spoliation of our woods, led to the devising of our
(German) present most admirable regulations for the
management of our woods and forests. If our forests
were parcelled out into as many portions and divided

THEORETICAL AND PRACTICAL AGRICULTURE. 159

among as many foolish hands as our arable land, we should
long ago have been without wood. There is the most
imminent danger just now, that the rapidly progressing
destruction of the Quinine or Peruvian bark-tree will, at
no distant period, deprive society of one of the most inva-
luable medicinal agents; and our only consolation is, that
when the last tree of the kind shall have fallen, the rational
culture of the plant will then begin which after a certain
number of years will again provide us with a permanent
supply of Bark.* | ‘

The expedients hit upon by certain writers on husbandry
to shut the eyes of agriculturists and their own, to the light
of science, and to make the comprehension of the laws of
the nutrition of plants inaccessible to the mind and under-
standing, are truly most remarkable; and the history of
agriculture will surely preserve the memory of them. ‘To
this day the farmer of the Wetterau justly regards the sale
of his manure, not only as a disadvantage, but as a positive
shame: itis an object of ambition with him to raise the
largest possible amount of it on his fields. He has been
taught that there is in manure a certain inconceivable and

* Tt is asserted that our high farmers “ know the art of extracting from the
same piece of land more grain than could be got from it in the seventeenth
century.” I doubt the correctness of this assertion, and think it quite within
the limits of possibility that accurate statistical researches might prove the
very reverse to be the case. Those who can look back a generation will
probably remember, as I do, that large tracts of land which now are culti-
vated-and bear produce, lay formerly waste (an advantage for which we are
no doubt indebted to the rotation system). The question arises here whe-
ther, admitting the production to be larger now than formerly, the increase
is not rather owing to the simple fact that the extent of producing surface is
now considerably greater than it was. A distinguished American Economist,
Carey, assures me, that accurate statistical inquiries instituted in 1850 by the
“Times” Commissioner have shown that England at that time produced
actually 2,000,000 quarters of corn less than in 1774, according to Arthur
Young. I will not venture to guarantee this fact, which, if true, would cer- .
tainly look very significant.

160 THEORETICAL AND PRACTICAL AGRICULTURE.

indefinable something which is to be met with in manure
alone, and in no other matter ;—that ash and gypsum are
not food for plants, but serve, like the whip of the carter
to his lazy horse, to stimulate the activity of sluggish
plants. Even up to the present time, they look upon the
mineral constituents in guano and in bone earth, as not in
the slightest degree contributing to the nutrition of plants,
but simply as auxiliary stimulants applied to the soil for the
purpose of promoting the production of stable dung.

The worshippers of manure act in defence of their notions
in a somewhat similar way to the Birkenfeld peasantry of
last century, who grievously complained that government
wanted to compel them to cultivate a foreign weed (clover).
They told the officers in the plainest terms “to stick to
their last, and concern themselves about things they had
learned. As for husbandry, they (the peasants) were likely
to know much more about it than all the margraves and
overseers in the world.’ They did not wish to give the
matter a single trial, and when ultimately compelled to
sow the clover, they demanded, after a time, a magisterial
inspection of their fields, and showed ‘that not a leaf of
the clover had come up;” and no wonder; for it turned out
at last, that the peasants had bozled the seed before putting
it in the ground. In our day scientific principles are treated
somewhat in a similar manner; the professors of modern
agriculture boil them in their pot, and it is then openly
shown that not a grain has come up. These gentlemen
will on no account consent to see farmers freed from the
compulsory rotation of crops; this they must understand
much better than anybody does. But their own doctrine
is barren, because it has no roots. Whatever good precepts
their books contain, the agriculturist knows already, for
these teachers derived their information from him; but
such precepts as originate with themselves, inspire the far-

THEORETICAL AND PRACTICAL AGRICULTURE. 161

mer with no confidence, lead to no profitable ideas, do not
increase his energies nor exalt his faculties.

If they would confine themselves to simply telling the
agriculturist what this or that farmer has at any time done
on this or that field ;—that land requires to be well ma-
nured ;—that guano and bone-earth constitute excellent
manures, and that Chili-saltpetre, gypsum, and marl are
also not to be despised,—surely no one would blame them
for disseminating these truisms. But they have gone much
further, and in their blindness and shallowness have laid
the axe to the very root of agricultural prosperity—and
this can and must no longer be permitted.

They maintain and teach that in guano, Chili-saltpetre,
and bone-earth, nitrogen is the only common constituent
that is deserving of consideration, and that it is to this ele-
ment alone that increased productiveness is to be attri-
buted.

They teach and wish farmers to believe, that 10 to 12
pounds of the urine of cattle, which contains no phosphoric
acid, will produce the same effect as 1 pound of guano,
which is rich in phosphoric acid,—simply because both sub-
stances contain the same quantity of nitrogen. They teach
and maintain that the fertilising action of guano and of
farm-yard manure depends upon the same cause, viz., their
amount of nitrogen, and that guano must produce the same
effect as farm-yard manure.

All this they maintain without adducing a single fact in
support of their assertions, or having once sought to show,
by some unexceptionable instance, that the application of
nitrogen by itself can make an exhausted field yield for a
number of years the same crops of corn or other produce
that are actually got from it by the application of farm-yard
manure, guano, and bone-earth. That nitrogen could really
produce such an effect everybody at all acquainted with

162 THEORETICAL AND PRACTICAL AGRICULTURE.

the elementary principles of the nutrition of plants must
know to be an actual impossibility.

But these teachers go even much beyond this. In No.
247 of the Swabian Mercury, of the 15th October, 1856,
there is an article on the Chili-saltpetre and its use, written
by a Professor at one of the most renowned Agricultural
Academies of Germany, in which the reader is told that
‘Ca hundredweight of Chili-saltpetre will produce the same
effect as 75 to 80 cwts. of farm-yard manure, whilst a cwt.
of guano will only be equivalent to 60 or 70 ewts. of the
latter;—that a cwt. of Chili-saltpetre will produce about
three cwts. of grain; that its action, however, is only per-
ceptible the first year; that its price is 12 florins (20s.) per
cwt., and that, accordingly, the corresponding value of a
cwt. of farm-yard manure would be 9 krs. (8d.)”

This announcement may be said to be the very culminat-
ing point of the theory of our teachers of modern agricul-
ture; it is evidently intended to induce the well-to-do pea-
sant, and the small land-owner, who may be in want of
manure, to buy Chili-saltpetre—a salt which contains none
of the ash constituents of the cereals, but is composed sim-
ply of nitric acid and soda; one cwt. of which, we are
assured, will produce three cwts. of grain. Its effect, it is
true, lasts only one year, but it will, nevertheless, prove
equivalent to 75 or 80 cwts. of farm-yard manure, the bene-
ficial action of which on a field may still be observed after
seven or eight years. The simple comparing of Chili-saltpetre
to guano and farm-yard manure is, in itself, an offence against
common sense; and the recommendation of that salt, at the
expense of guano and farm-yard manure, is an injury in-
flicted on the property of thousands by an unprincipled or
ignorant adviser.

A proceeding of the kind may be excusable in a com-
mercial traveller soliciting orders for a speculator in Chili-

THEORETICAL AND PRACTICAL AGRICULTURE. 1638

saltpetre; but if we find that such notions are disseminated
by teachers of agriculture and professors at agricultural
institutions ; if we see those teachers intent upon making
the farmer believe, by means of a spurious array of figures,
entirely inapplicable in the great majority of cases, that
nitrogen possesses for him twice the value of phosphoric
acid, five times that of potash, and twelve times that of
phosphate of lime—it is time for all sensible men to unite
and call these teachers to account. We may surely demand
of them what is only right and fair, viz., that they simply
prove the truth of their theories by a faithful statement of
accurately observed and properly guaranteed facts.
Although it has, in these last years, been most plainly
demonstrated to these men that their views and theories are
founded in error, this has not brought conviction to the
mind of a single individual. One after another has come
forward with the vain and impotent attempt—not to adduce
new and striking proofs in support of their doctrine—but
to suggest doubts against the true import and bearing of the
facts brought forward in refutation of their views. Not one
of them has ever even dreamt of appealing, in support of
the truth of his views, to his own numerous experiments
and chemical analyses on which those views are based ;
because all of them know full well that their labour in this
line will not bear the test of a rigorous scientific examina-
tion. In their distress they now turn for help to the same
agriculturists whom they had, by these analyses, persuaded
that nitrogen was the only active agent in guano, bone-
earth, and rape-dust, and appeal to them to bear witness
that they have given them good advice, and that their
theories have been borne out by practical experience; that
a pound of ammonia has a practical value of twelve groschen,
a pound of bone-earth of only one groschen. But the prac-
tical man, in truth, knows nothing of the action of ammo-

164 THEORETICAL AND PRACTICAL AGRICULTURE.

nia or of nitric acid, or, at all events, nothing but from
hearsay; for he has not been taught by the agricultural
chemist that guano, bone-earth, and rape-dust are excellent
manures, but the latter has, on the contrary, learned this
fact from him, and has simply thrown in his own little
hocus-pocus, that a few stray beams of the sunshine of their
beneficial action might be reflected on him.

LETTER XI.

Ammonia is an element of food indispensable to Plants—Comparison of thé
action of Water and Ammonia—Ammonia is an element of fooc and a
Solvent of Mineral Matters in the Soil—Ammonia alone, or its Salts, useless
to Plants, without Mineral Food—Vast amount of Ammonia in arable Soils
—The “Nitrogen” theory of Manures—The error of attributing the chief
value of a Manure to its Nitrogen—The reason why the quantity of Nitro-
gen in Guano and Excrements may be taken as a standard of their Agri-
cultural value—Proper mode of Comparing the relative effects of Guano,
Ground Bones, and Chili-saltpetre—The Loss of Fertilising matter in the
Flesh and Grain carried to large towns; the constant loss of Phosphates in
the Excrements of the inhabitants—The importation of Guano most
inadequate to replace this loss—Superiority of Human Excrement over
Guano as a Manure for Corn Fields—Tobacco, Potatoes, and Beet-root are
more exhausting to a soil than Wheat—Injurious influence of extensive
Cultivation of the Vine on the production of Corn and Wheat—Effect of
the Subdivision of the Land.

As an element of food, ammonia is as indispensable to
plants as carbonic acid; a brief consideration of the part
which water plays in the nutrition of plants will best enable
us to understand the fertilising action of ammonia in
manure. |

Water subserves a double purpose in vegetation; it sup-
plies to the plant in one of its constituents an indispensable
element, and serves besides to render mineral matter in the
soil fit for absorption by the roots. Though the soil be
ever so rich in the elements of food for plants, still the latter
will not grow in hot weather, if there be a deficiency of
moisture in the soil; for the moisture in the soil is the
channel through which mineral food has to reach the inte-
rior of plants.

166 THEORETICAL AND PRACTICAL AGRICULTURE.

When there is a failure in the supply of mineral food,
the leaves absorb neither carbonic acid nor ammonia from
the air; and vegetation is brought to a stand-still, although
the air contains more moisture in hot days than in cold,—
this moisture being of no avail to the plant. With a defi-
ciency of water in the ground, sunny and warm days,
which under other circumstances would be the most fa-
vourable for growth, actually prove the most pernicious,
particularly for summer plants, which have not yet had
sufficient time to push their roots deep into soil where there
still exists a supply of water that might convey food to
them. In such cases barley grows barely a hand high and
shoots into ear, and potatoes produce no tubers. One good
shower at the right time changes this state of matters as if
by magic. If the farmer could bring down rain upon his
fields at the right time, as the gardener can water his flower-
pots, all plants would give a maximum yield, pre-supposing
of course, that there is a sufficient available supply of food ;
for if there be a deficiency of the latter in the soil, a corres-
ponding diminution in the maximum yield must in conse-
quence be expected. Plants therefore absorb carbon and
nitrogen in proportion as the water conveys to them more
of the mineral constituents of the soil; their growth is accele-
rated, and the weight of the crop increased.

It is exactly the same with ammonia. If we increase the
quantity of ammonia in the air or in the soil, the plant
finds at a favourable juncture a larger supply of this element
of food than usual, and the consequence is, that a corres-
pondingly larger amount of the mineral elements of food is
rendered available. As the leaves of a plant can daily
come in contact with only a certain volume of air, they
can of course take up from it no more ammonia and car-
bonic acid than this volume of air contains; the absorption
of these substances and the increase of the plant consequent

THEORETICAL AND PRACTICAL AGRICULTURE. 167

thereon require accordingly a given time. If a plant
every day absorb an equal amount of these elements of food,
it will receive of course twice as much in two days as in one.

If a plant on favourable days received twice or four
times the usual supply of mineral food, the surplus must
remain inactive until the leaves shall have taken up from
the air sufficient carbonic acid and ammonia to combine
with these mineral elements in the formation of constituent
parts of the frame of the plant. None of the elements of |
food will act without the presence and co-operation of the
others. If, accordingly, we increase the amount of ammonia
in the soul, or in the air (of carbonic acid, there is generally
no deficiency), the development of the plant will, the other
conditions of its growth being equal, be considerably
quickened; in other words, the plant will grow in bulk
and substance much faster than under ordinary circum-
stances. Familiar illustrations of this may be seen every
day in hot-beds. Had the mineral elements of food not been
present in the plant and available for its nutrition, the ammo-
nia would not have had the slightest effect on the increase
of the bulk of the plant.

It need then excite no wonder that the application of
guano to a field should so largely increase the yield of
corn; for guano contains not only the mineral elements
which a soil must possess to produce corn, but also in the
ammonia an indispensable element of food, which serves to
quicken their action and to shorten the time required for
their assimilation. On many fields the ammonia in the
guano may, if the weather prove propitious, possibly effect
the assimilation of double the ordinary quantity of these
mineral constituents, and thus render the amount of pro-
duce yielded in one year equal to what would have been
otherwise obtained in two years by these mineral matters
alone.

168 THEORETICAL AND PRACTICAL AGRICULTURE.

It is clear also that ammonia used by itself in a soil con-
taining a sufficient supply of the elements required for the
production of a corn crop, must exert a favourable action
on the increase of the produce. But as in the large crop
reaped, there is now removed from the field a greater pro-
portion of the conditions upon the presence of which the
efficacy of the ammonia depended,—if the application of
ammonia be continued, and no restitution be made to the
soil of the mineral elements removed,—then the yield must
necessarily diminish, in the years following, in the same
proportion as it was higher in the first and second years.

In one word—ammonia is a most useful manure when it
is accompanied by the mineral elements which render it
active, or when it finds in the soil those conditions which
are necessary to its efficacy; it is absolutely of no-value to
the farmer if he neglect to restore or supply these elements.

In a soil sufficiently rich in nitrogen, but poor in certain
mineral elements indispensable to the growth of many
plants, the application of ammonia, or of its salts, is at
any rate useless, and often absolutely injurious. In such
a soil, which simply is deficient in a proper supply of phos-
phoric acid, a dose of that substance, unaccompanied by
ammonia, will produce the same fertilising effect as guano,
only, probably, in a higher degree. The General Commit-
tee of the Agricultural Society of Bavaria, at Schleissheim,
caused a portion of one of the poorest worn-out fields in the
vicinity of Munich to be manured, by way of experiment,
with acid phosphate of lime (phosphorite); the result was,
a crop of summer wheat double in amount to that yielded
by an equal portion of the same field unmanured. Had
guano been the manure used in this case, the crop would
most indubitably have far exceeded that reaped from the
unmanured plot, and a supporter of the so-called nitrogen
theory would as unquestionably have ascribed the effect to

THEORETICAL AND PRACTICAL AGRICULTURE. 169

the ammonia contained in the guano, which could not pos-
sibly have had anything to do with it, in the foregoing
experiment. The same manure, viz., acid phosphate of
lime, has been applied with equal success elsewhere, with
out any co-operation of ammonia, and frequently larger
crops of grain have been obtained than from the use of
guano; it is, therefore, quite evident, that for a field in that
condition ammonia is almost quite valueless. The expla-
nation also of this fact has been ascertained by chemical
examination: it has been found that most fields contain,
within a depth of from ten to twelve inches, a hundred,
five hundred, often even a thousand times more ammonia
in a similar form, than is present in rotten farm-yard
manure, in bones, or rape-dust; it is, then, quite clear, that
where the soil happens to be deficient in even one of the
indispensable mineral elements of food, the existing great
store of ammonia will be of no avail in increasing the pro-
ductiveness of the land. |

In the vicinity of Magdeburg, the residue left after the
distillation of beetroot-molasses, which contains the soluble
salts of the beetroot, (no salts of ammonia) has, of late, been
used as a manure, and I have been assured that fields
treated with it have yielded, several years in succession,
most abundant crops of rape, beet, &c.

For each field there exists some effective agent of this
kind; but it will never be found, if we rest contented with
simply chanting the praises of ammonia. As we have seen,
in Letter IJ., the soil never contains free ammonia; and in
the rotten farm-yard manure the greater proportion of the
liberated ammonia enters into chemical combination with
the humus-constituents of the dung—being taken up by
them directly from the liquid portion, which accounts for
the fact that the latter is comparatively so poor in that
ingredient.

8

170 THEORETICAL AND PRACTICAL AGRICULTURE.

Free ammonia, or an ammoniacal salt, put upon a field,
immediately forms with the constituents of the surface soil
a combination from which the plant subsequently derives
this element of food. In this way, the ammonia conveyed
to the soil in rain goes on accumulating; it would, there-
fore, be an act of common sense to expend no money in
the purchase of this dearest of all manuring agents, before
first making sure that phosphate of lime, either alone, or in
conjunction with sulphuric acid, or ash, or the two together,
or lime, has failed to stimulate the productiveness of the
field, in the first place, for underground plants (turnips,
potatoes, &c.), and for the subsequent crop of cereals. It
is only after making such trials, that the employment of
ammonia can be justified.

Let it not be thought, however, that the notion of the
professors and advocates of the so-called nitrogen theory,
which makes the nitrogen, or the ammonia, the principal
agent in manures, and the pivot upon which all agricultural
production turns, is purely imaginary and absolutely base-
less. This notion has, on the contrary, arisen from a very
pardonable error, formerly but too common in science, and
which is still occasionally met with at the present day.

It is quite true that the agricultural value, for the produc-
tion of grain, of the various sorts of guano, and of all excre-
ments of animals, may be accurately determined by the
proportion of nitrogen or ammonia contained in them.
The mistake made in the matter essentially les in this,
that, taking their stand upon these facts, which are per-
fectly true in themselves, people attributed the action of
these manures to the nitrogen, which, indeed, performs a
part in this action, but, in most cases, only a subordinate
one. This is the same error which Lavoisier and Davy
committed in designating, the one, oxygen, the other,
hydrogen, as the acid-generating principle.

THEORETICAL AND PRACTICAL AGRICULTURE. 171

To comprehend this fact, we must bear in mind the com-
position of grain, of flesh, and of those constituent parts of
plants which serve to form blood, and which have a com
position similar to that of flesh. All these matters contain
the combustible and incombustible constituents of the
blood. A person living on bread receives into his organ-
ism the ash-constituents of the grain which has furnished
the flour for the bread; his excrements contain the ash-
constituents of the same grain. Out of the elements of the
bread flesh is made, and the excrements of men or animals
living on flesh are in their elements identical with those of
men or animals living on bread or seeds. Bread, flesh, and
blood, contain an ingredient rich in nitrogen, which, taken
in the food, serves to sustain the vital functions, or the
change of matter in the body: the nitrogen of this ingre-
dient is again every day eliminated in the urine and feces,
in the same quantity in which it has been partaken of in
the food.

The excrements of men and of animals, therefore, not
only contain the ash-constituents of the seeds, the flesh and
the component parts of the roots, tubers, herbs, &c., that
have served to form blood and flesh in the animal organ-
ism, but they also contain the far greater proportion of the
nitrogen of these seeds, and of the blood and flesh-forming
elements. As we have already had occasion to observe, it
has been demonstrated by the most accurate chemical
analysis,* that there is a fixed and invariable ratio between
the amount of nitrogen in seeds and the quantity of phos-
phoric acid or of phosphates contained in them (between
the nitrogen and the ash-constituents of the seed); so that,
if we know the proportion of nitrogen in seeds, we can,

* See “Results of agricultural and chemico-agricultural experiments con-
ducted by the General Committee of the Agricultural Society of Bavaria at
Munich; Cotta’s Literary and Art Institution, 1857.”

172 THEORETICAL AND PRACTICAL AGRICULTURE.

from this, calculate the amount of phosphoric acid, or of
phosphates, present in them.

Now, in the solid and liquid excrements, these several
constituents are naturally contained in the same, or very
nearly the same, fixed relative proportions as in the seeds.
The solid and fluid excrements together contain the nitro-
gen and the ash-constituents of the bread, flesh, &c. of the
consumed food; and we can therefore readily understand
how we might, by ascertaining the amount of nitrogen in
an excrement, estimate, in an analogous way, in a tolerably
exact manner, the quantity of mineral constituents of seeds
or of flesh present in it.

In point of fact, the original relative proportion between
the nitrogen and the ash-constituents in excrements is
altered. The nitrogen is converted in the putrefactive
process into ammonia, a portion of which is lost by evapo-
ration; and even before the process of decomposition has
set in, part of the nitrogen present is carried off, together
with the most efficacious soluble salts, in the liquids which
ooze away. This latter loss, however, might be guarded
against, and ought to be so, by the use of absorbing earths.
The proportion of nitrogen in the contents of latrines, or in
poudrette, in farm-yard manure, and in guano, affords,
therefore, no proper standard of their agricultural value,
which depends upon the ash-constituents of seeds contained
in them; but of two sorts of guano analysed, we can, with
tolerable certainty, regard that one as the purest in which
is found the largest per centage of ammonia; any adulte-
ration of the article lessens that proportion. The same
remark applies to poudrette which very often contains as
much as fifty per cent. of sand (sweepings) and other
extraneous matter unfit for the nutrition of plants; and
probably, also, this holds good for farm-yard manure.

It is therefore by no means absurd, but quite correct, to

THEORETICAL AND PRACTICAL AGRICULTURE. 173

say, that the value of the several sorts of guano, of pou-
drette, and of farm-yard manure, bears a certain relation to
their amount of nitrogen. But the inference drawn from
this fact, that the agricultural value of these manures, and
their beneficial action upon the soil, are entirely dependent
upon this relative proportion of nitrogen, and that, accord-
ingly, ammonia and its salts might be used with equal suc-
cess in cultivation, in lieu of them, is over-hasty, and
entirely devoid of all foundation. Were a farmer, by the
advice of the apostles of this so-called nitrogen theory, mad
enough to manure his fields, even for ten years only, con-
secutively with salts of ammonia, or with Chili-saltpetre,
and were he, confidently relying upon the perfect fitness
of these salts to replace farm-yard manure, poudrette, and
guano, to sell off from his fields the entire produce, he
would assuredly be a beggar at the end of this period. If
all agriculturists in Germany were to agree never to return
to their fields the mineral constituents of their manure-
heaps, because their teachers have assured them that the
soil is inexhaustible in these elements, half the population
of Germany would be starved to death before the end of
ten years.

It is, altogether, one of the most discouraging signs in
agriculture, that frequently the best-informed men will, in
judging of the value of a manure, and of its effect, act as
if they were devoid of judgment and common sense.

In comparing the action of guano, bone-earth, and Chili-
saltpetre, it will not do to draw a line under the calculation
at the time of harvest, or after the expiration of a year,
and argue that guano or Chili-saltpetre is a better manure
than bone-earth, because so many more pounds of corn have
been yielded by the use of the former than by the latter.
Common sense tells us that the effect of individual manures
must be judged of by the condition in which they leave the field.

174 THEORETICAL AND PRACTICAL AGRICULTURE.

It is very evident that if after a large crop which has
been obtained by the use of Chili-saltpetre in one year, the
soil has required in the following year a double quantity
of manure to yield the same amount of produce, much
money has in such a case been laid out to no purpose; and
I greatly fear, if an exact reckoning be kept of the produce
of their fields for a series of years, and also of the expendi-
ture of manure, in addition to Chili-saltpetre, agriculturists
will find that for the money spent in the latter agent, they
have received scarcely any other return than a very beau-
tiful deep green colour of their crops in the first period of
their vegetation.

A comparison of the action of guano with Chili-saltpetre,
and_bone-earth (or phosphorite), can be made only after
several years. If guano applied to a plot of land very per-
ceptibly increases the potato crop in the second, and the
clover crop in the fourth year, whilst a dose of Chili-salt-
pette of the same pecuniary value is not followed by a
similar increase, those after-effects must be taken into’ac-
count if we would avoid drawing a superficial estimate of
the value of the two substances.

When the agriculturist who makes comparative experi-
ments with guano and other manures, and appears to have
obtained in the first year from the guano the most favour-
able results, points to its greater proportion of nitrogen and
draws the conclusion that these greater effects have been
directly due to this element, we may well ask him why he
has not also made a comparative experiment, upon an equal
piece of land, with a similar quantity of ammonia to that
which is contained in guano, and in this way obtained
a standard by which to measure the effect of ammonia in
guano.

But a proceeding of this kind has never yet been thought
of by any one of these experimenters, who also keep from

THEORETICAL AND PRACTICAL AGRICULTURE. 175

the farmer the fact proved by the most extended and accu-
rate experiments of Lawes, Kuhlmann, and others, that a
pound of ammonia in guano produces five times the effect of
the same quantity applied in the form of a salt of ammonia.
(The action of pure ammonia is altogether unknown.)
Now it is quite clear that the more powerful effect of the
ammonia in the guano is simply owing to the presence and
co-operation of other matters; and when the combined
action of these latter and the ammonia is found to be four
times greater than that of the ammonia alone, then wher-
ever it is thought desirable or requisite to use ammonia it
will evidently be a wise step to provide for the presence of
these matters, that in such cases likewise the action of the
ammonia may be increased five-fold.

When an agricultural chemist (Dr. Stéckhardt) asserts
that “he chiefly owes to guano his positive conviction of
the great importance of nitrogen compounds that are easily
assimilated, and is thus indirectly indebted to it for the
most glorious acquisitions achieved by his labours in the
field of agricultural chemistry,” the latter alone is true thus
far, viz. that if it had not been for guano the world would
scarcely have heard of the labour of this individual in the
field of agricultural chemistry. A man of science ought
not to cling to a cork buoy to enable him to swim; and
if it keeps him afloat he ought to be grateful for this, but
not proud of it. Guano requires no cork buoy; it would
assuredly have made its way.as railways have done, as indeed
it has done in other countries to a much greater extent than
with us, without requiring the least aid at the hands of the
chemist. Things which bring in money will always make
their own way.

When agricultural chemists maintain that ammonia or
its salts are the universal means for the growth of wheat,
or acid phosphate of lime for that of the turnip tribe—they

176 THEORETICAL AND PRACTICAL AGRICULTURE.

simply show thereby that they do not understand the essen-
tial principles of the science of agriculture.

The corn-growing agriculturist removes from a hectare
(24 acres) of his wheat field, in an average crop of corn of
2000 kilos, 70lbs. of the mineral constituents of the grain ;
of which 84 pounds consist of phosphoric acid and 21 pounds
of potash, and he supplies these to the consumers in large
towns. In an ox of 550lbs weight, the town receives
183lbs of bones, containing nearly 120lbs of phosphate of
lime; in the flesh, hide, and other parts of the animal 15lbs
of phosphates, which are identical with the constituents of
the seeds of rye.*

The annual fluid and solid excrements of a million in-
habitants of large cities (men, women, and children), weigh
in the dry pulverulent state 45 million pounds; in which are
contained 10,800,000 pounds of mineral substances, mostly
ash-constituents of bread and meat (not including five mil-
lion pounds weight of bones of the slaughtered cattle, &c.,
nor the mineral substances in the evacuation of horses, &c.).
These human excrements alone contain 4,580,000 pounds
of phosphates.

This enormous drain of these matters from the land to
towns, has been going on for centuries, and is still going on
year after year, without any part of the mineral elements
thus removed from the land ever being restored to it; a
very small proportion only is turned to account in the
gardens and fields in the more immediate vicinity of
towns.

* In the city of Munich there were slaughtered in the year 1855-56,
16,301 heads of cattle, which, at an average of five cwt., weighed 8,150,500
Ibs.; besides which there were slaughtered 66,186 calves, swine, and sheep,
giving, at an average of 70 lbs. each, 5,675,020 lbs.—not reckoning the cattle
slaughtered, at the free butcheries, by the keepers of taverns and eating-
houses.

THEORETICAL AND PRACTICAL AGRICULTURE. 177

It is perfectly absurd to suppose that the loss of these
matters which are so essential to the productiveness of a
soil should have had no influence upon the amount of its
produce. Indeed, even the most prejudiced agriculturist
cannot help feeling some alarm at the enormous extent of
the loss, if he reflects upon the amazing increase in the
yield of corn and flesh which has taken place since farm-
ers began, by the use of guano, to restore to the despoiled
fields only a very small fraction of the corn and flesh con-
stituents carried away from them. I have already remarked
upon the identity of the constituent elements of guano with
those of human excrements. In a series of very instructive
experiments made expressly for the purpose in six differ-
ent parts of Saxony, it was found that a field manured with
guano gave in three successive years for every 10 pounds
of guano used, 15 pounds of wheat grain, 40 pounds of
potatoes, and 28 pounds of clover more than was reaped
from an unmanured plot of land of the same kind and
extent. According to the condition of the field the surplus
thus reaped varies from 10 to 20, and in England up to 22
and even 28 pounds of corn, for every 10 pounds of
guano used.*

* “Tn the United States distances of hundreds and thousands of miles sepa-
rate the places where the corn is grown from the markets; the consequence
of this may be seen in the fact that the soil is almost everywhere exhausted,
and that the prosperity of the country is declining, instead of increasing.

“The rate at which this decline is progressing, has lately been shown by a
distinguished agriculturist, from whom we learn: ‘That the phosphoric acid
and the potash taken annually away from the fields, without any compensa-
tion worth mentioning being made to them, are at the current price of the
market worth twenty million dollars; that the ash-constituent of 600,000,000
bushels of corn are annually carried away from the land without any mate-
rial restoration of them; that the entire annual waste of the mineral consti-
tuents of corn is equal to 1,500,000,000 bushels of corn.’

“To suppose, says the author of these estimates, that this state of things
could last, and we as a nation increase in wealth, is simply ridiculous, It is

8*

178 THEORETICAL AND PRACTICAL AGRICULTURE.

It may therefore be safely assumed that the importation
of a million cwt. of guano is equivalent to an increased
production of 2,000,000 ewt. of corn which could not
have been raised by the existing stock of home-made
manure alone; this latter performs its own part in increas-
ing the produce exactly the same as if the guano had not
co-operated with it.

only a question of time, and time will solve the problem in a way not to be
mistaken. What we lose with our system of destroying the soil, and wast-
ing its resources, is the very essence of our existence.

‘Our land has not yet grown feeble from this loss of its life-blood ; but the
hour is indicated when, should the present system be persisted in, the last
throb of the heart of the nation will cease,—when America, Greece, and
Rome will stand side by side amidst the ruins of the past.

“The national economic question is not how much we are able to produce,
but how much of our annual produce is returned to the soil, Labour spent
in the spoliation of the soil is worse than labour thrown away. In the latter
case the loss falls upon the present generation, in the former, poverty is the
inheritance of posterity.

‘“‘ Extravagance, Mr. President, is a crime which finds its punishment in
the natural, moral, and political decay to which I have invited your atten-
tion. Its effects may be seen in the fact that in New York, where the ave-
rage yield of wheat was from 25 to 30 bushels 80 years ago, it is now only
12 bushels; Indian Corn gives only 25 bushels. In Ohio, a State which 80
years ago was still a wilderness, the average yield of wheat is under 12
bushels, and is decreasing instead of increasing. In Virginia there is an
extensive tract of land, once the richest in the State, which now produces
only an average yield of wheat of less than seven bushels; whilst in North
Carolina land is cultivated which produces little more than the same yield of
Indian corn.

“In Virginia and Kentucky tobacco was grown until the soil was com-
pletely exhausted, and had to be abandoned; and in the cotton districts we
meet with a state of exhaustion unexampled in the world, for the shortness
of the time in which it has been brought about. The growers of cotton and
tobacco live upon their capital; in the produce of their fields they sell their
fruitful soil at so low a price, that for every dollar they receive they destroy
to the value of five dollars.”

(Letters to the President on the Foreign and Domestic Policy of the Union,
and the effects as exhibited in the condition of the people and the State. By
H.C. Carey. Philadelphia, J.B. Lippincott & Co. 1858. Tenth letter, p. 54.)

THEORETICAL AND PRACTICAL AGRICULTURE. 179

In the flesh and the produce of the field we have for
centuries supplied to the large towns the constituent ele-
ments of guano, and have never brought this guano back
again; and we now send vessels to Chili, Peru, and Africa
for this substance. For every 45 million pounds of guano
we pay the foreigner 3 million florins. By the exporta-
tion of these elements our fields have lost in productiveness ;
were it not so, how could it have been conceivable or pos-
sible for us to have been able to raise their fertility by the
importation of these elements? Where a field is truly in
prime condition, no manuring agent can possibly increase its
productiveness ; the surplus yield attained by the use of
guano is therefore usually much less on well than on ill
managed estates. Whilst in the case of the former it no
longer gives a remunerative return so soon as it rises some-
what higher in price; the bad manager will however con-
tinue, and justly so, to praise it as a profitable agent.

In the year 1855-1856 above 10 million ewt. of guano
were imported, of which the greater portion remained in
England. In the course of half a century above 60 mil-
lions ewt. of bones have been imported into that country ;
yet all this mass of manure is not worth mentioning when
considered in relation to the arable surface of Great Bri-
tain, and is but as a drop when compared to the sea of
human excrements carried by the rivers to the ocean.

The loss annually sustained by the land can only be
very partially remedied by the purchase of foreign manures.
In the year 1852, the consumption of guano in Saxony
amounted in the districts of Dresden, Leipzig, Zwickau and
Bautzen to 60,000 ewt., which gives 16-9 cwt. for every

-400 acres of land (= 553 hectares), or 41 pound per acre
(3°82 kilos per hectare). In these 3°82 kilos of guano (of
the better sorts) there are contained not above 1§ kilo of
the mineral constituents of seeds; whereas there are annu-

180 THEORETICAL AND PRACTICAL AGRICULTURE.

ally removed from the fields 35 kilos per acre in the ccrn
crop alone. If therefore Saxony imports in a year
1,428,000 cwt. of guano containing 85 per cent. of ash-
constituents (for about 5$ million thalers), this is no more
than has been taken away from all the Saxon fields in a
single corn crop.

No more importance need be attached to these figures
than they deserve. ‘They are sufficiently precise to show
that our fields would be incalculably more fertile; that we
might now produce infinitely more food for man upon the
same arable area; that we should not be forced to sacrifice
one-half of it to cattle—if our ancestors had only prudently
and carefully brought back from the towns and restored
to their fields the guano carried away from them in the
produce.

There is not to be found among the industrial classes a
set of men more intent upon immediate and temporary gain
than the common peasants, and less capable of making cor-
rect calculations in an industrial point of view; although
one would suspect the very reverse to be the case.

The prudent agriculturist who purchases potatoes from
the peasants in his neighbourhood, for the purpose of dis-
tilling alcohol from them, or rape seed for its oil, knows
that every two acre crop of potatoes which the peasant sells
to him, will in the residuary matter yield him three crops
of rye (seed), or a full crop of rape. He knows that every
cwt. of rape in oil-cake is worth two cwt. of wheat grain to
him ;—and in establishing a distillery or oil mill, he takes
into due account the advantages derived from this addition
to the conditions of the fertility of his land.

The peasant from whom he purchases the potatoes or
rape-seed knows that the buyer looks upon this additional
supply of fertilising matter from the residues as wmportant,
but he himself considers it of no value to his land. It never

THEORETICAL AND PRACTICAL AGRICULTURE. 181

occurs to him that it would be a prudent act to retair. the
manure constituents for his own fields at the sacrifice of a
portion of the money received for his produce.

The seller, if he is also a farmer, should sell only the oil
of his rape seed, and only the starch of his potatoes,—for
in this way alone can a proper circulation be maintained.

But the agriculturist sells not only corn, but also pota-
toes, rape-seed, beetroot (to the sugar boiler), tobacco, hemp,
flax, madder, poppy, and wine.

Whilst the corn and flesh growing agriculturist exports
in the produce of his fields only phosphoric acid, alkalies,
and alkaline earths, he retains on the land the elements of
the straw and of the fodder plants which pass in the rota-
tion of his crops from one field to another. The deep root-
ing clover and the plants of the turnip tribe take them up
from the sub-soil, and in the form of farm-yard manure,
continually accumulate them in the surface soil. The ma-
nure and the surface soil receive every year an additional
supply of soluble silicic acid, alkalies, and salts with alka-
line bases; but the proportion of phosphates in them is
constantly on the decrease.

Hence it will be readily understood why the use of these
manuring agents—viz. soluble silicic acid, potash, and pot-
ash salts—will not have the slightest beneficial effect on the
fields of the corn and flesh growing agriculturist; for his
fields contain already an excess of these agents which
remain inactive from the want of phosphates. We can
further understand why the corn and flesh growing agri-
culturist should regard in the most important hght the
supply of phosphates, of guano and of human excrements;
and hold the other elements of food for plants as almost of no

value.

On such fields, simple manuring with human excrements,
with or without the co-operation of farm-yard manure, may

182 THEORETICAL AND PRACTICAL AGRICULTURE.

produce large corn crops for an infinite number of years in
succession; but the continued use of guano exhausts also
this land. ‘The excrements of man contain the full comple-
ment of mineral elements removed in grain and flesh; but
in guano there is wanting a certain quantity of potash to
replace fully these ash constituents. Hence on soils poor
in potash (on lime and sandy soils), the action of guano after
a certain time perceptibly diminishes, and its efficiency 1s
then restored by the addition of wood ashes, rich in potash.

It is a very different matter with the grower of potatoes
and beetroot, who sells his produce to the distiller-or to the
sugar maker.

In the average produce of three hectares of land, the
potato grower sells and takes away from the soil the grain
constituents of four wheat crops, and upwards of 600 pounds
of potash in addition. |

In the produce of three hectares of land the beetroot
grower sells and takes away from the soil the grain consti-
tuents of four wheat crops, and 10 cwt. of potash besides.
The single sugar manufactory at Waghiusel supplies to
commerce every year 200,000 pounds of salts of potash
obtained from the residue of the molasses, and which were
originally derived from the beetroot fields of Baden.

It is evident that, in the cultivation of potatoes and
beetroot, two causes of exhaustion operate on the fields:
these kinds of produce withdraw from the soil at each
harvest, one-third more phosphates than a wheat crop, and
in addition to these an immense amount of potash and its
salts. Beetroot and potato fields, abounding in potash, may
therefore have their produce augmented by simply manuring
with guano or-super-phosphate of ime; but as guano and
bone manure do not replace the potash removed in the
produce, the ultimate result is, that after a certain number
of years the land is found to be so much the more thoroughly |

THEORETICAL AND PRACTICAL AGRICULTURE. 183

exhausted. On other potato- and beet-root fields poor in
alkaline elements, farm-yard manure, which abounds in
alkalies, answers better than guano.

The growers of marketable plants are in the most unfavour-
able position as regards the restoration of the mineral ele-
ments annually carried off from their fields by these parts. A
tobacco planter takes away in the tobacco leaves an immense
amount of mineral elements (in clover-hay, for instance, not
above 10 per cent., in tobacco leaves, from 18 to 24 per cent.).
If he happens to be in possession of fields for green crops
which supply him with manure for the tobacco plants, he
is in the same position as the agriculturist who sells ana
alienates from his land the clover, turnips, &c. grown
thereon ; that is to say, in the course of a few years he is
sure to reach a point when his land will no longer produce
tobacco; and driven to procure elsewhere a supply of the
indispensable mineral elements, he now turns to his grain
and flesh producing neighbours, and purchases from them
at high prices their clover and turnips in the shape of farm-
yard manure. Now, if this neighbour, over estimating the
quantity of farm-yard manure in his possession, disposes of
a portion of it to the tobacco grower, he generally soon
perceives his error, by the diminution of his crops. He is
first of all made aware that manure cannot be produced at
will, and that the counsel given to him to “ grow more pro-
vender for his cattle, as corn crops will then be sure to fol-
low in due course,” is of no use to him; he finds that it
was his manure that for seven or perhaps ten harvests has
given him the sixth or seventh grain which constituted his
entire profit, and that in parting with his manure he has
_actually sold for a song his profits for many years to come.
Made wise by experience, he now sells no more farm-yard
manure.

The tobacco planter, finding he can no longer procure

184 THEORETICAL AND PRACTICAL AGRICULTURE.

manure from his neighbour, now applies to grain and flesh
producers living farther off, who have yet to find out by
experience what the neighbour has already discovered ;
and thus the sphere of his foraging operations in search of
manure grows wider and wider every year, until he finds
himself ultimately constrained to procure his manure from
towns, and to supply by other means the elements in which
the town manure is deficient.

The same state of matters we find also in countries where ©
the vine is extensively cultivated. Vineyards are generally
planted on slopes, and are destitute of arable surface soil ;
the soil is, comparatively speaking, infinitely poorer in the
elements of food for plants, than is the case with fields
situated in plains. Vineyards produce no manure; the
wanting mineral elements of food are supplied, within cer-
tain limits, from the neighbouring corn and pasture-fields ;
and the proprietors of these, if they have an opportunity,
in their turn pillage the neighbouring woods.

By deep digging the vine-dresser seeks to fit his poor
soil for the reception of the deep-rooting vine; and by the
occasional cultivation of lucerne and clover, he endeavours
to accumulate by their means in the surface soil, the
mineral elements in which it is deficient. He conveys to
his vineyard arable soil from fields which he has acquired
for that special purpose, and also applies as manure the
débris of disintegrated rocks abounding in alkaline matter.

The culture of the vine exercises accordingly on the pro-
duction of grain and flesh an adverse influence similar to
that caused by the planting of tobacco and other produce
grown for sale.

The producer of corn and flesh, according to the prevail-
ing system, robs his own land; the producer of wine and
marketable plants despoils in his turn the corn and flesh
producer; and lastly, large towns, like bottomless pits

THEORETICAL AND PRACTICAL AGRICULTURE. 185

gradually swallow up the conditions of fertility of the
greatest countries.

In this way the vine growers and tobacco planters of the
Palatinate and of the Bergstrasse exhausted the fields of
the Hessian and Badish Odenwald, and completed the ruin
of the already impoverished and encumbered peasant who
could not resist the tempting sound of the silver offered
him for his manure.

In the same way the sewers of the immense metropolis
of the Ancient World, engulfed in the course of centuries,
the prosperity of the Roman peasant; and when the fields
of the latter would no longer yield the means of feeding
her population, these same sewers devoured the wealth of
Sicily, Sardinia, and the fertile lands on the coast of Africa.

The fertility of the land has remained unimpaired for
centuries, In such parts only where an agricultural popula-
tion dwells crowded together on a comparatively small
area, and where the tradesman and craftsman inhabiting
the small towns thinly scattered over that area, till their
own little plots of ground with the assistance of their jour-
neymen.

When there are living on a (German) square mile of land
in that position, 2000 to 3000 people, no exportation of
grain or flesh is possible, for the produce of the fields is
only just sufficient to feed the population; a surplus for
exportation either never or very seldom exists, The fer-
tility of such a tract of land is kept up unimpaired by the
regular circulation of the conditions on which this fertility
depends. All the mineral constituents of the produce con-
sumed are brought back without diminution to the fields
from which they were taken. None of these elements are
ever lost; for everybody knows the inevitable consequences,
and is therefore careful to do his best to collect and preserve
them.

186 THEORETICAL AND PRACTICAL AGRICULTURE.

Now, supposing this same land falls into the hands of
ten great proprietors, the pillage and plunder system then
takes the place of the system of restitution and conapensa-
tion. The petty proprietor almost entirely restores to the
field what he takes from it; the large proprietor, on the
other hand, sends his grain and flesh for sale to the great
centres of consumption, and accordingly loses the conditions
for their reproduction. After a number of years the land
placed in this position will be turned into a desert waste
like the Roman Campagna.

This is the natural cause of the impoverishment of lands
by cultivation; there is no other; the teachers of modern
agriculture alone do not recognise this cause, and are with
all their power intent upon accelerating the ruin of Ger-
man agriculture, and making it irretrievable. Fertile fields
—so these teachers tell us—are inexhaustible in the con-
ditions of fertility; they only require the whip to stimu-
late them into action. Good fortune kindly sent guano to
rescue them in their utmost need,—the result of their own
teaching; but in her fatal hands this blessing is actually
turned into an instrument for impoverishing the land in
the course of time still more completely. But guano will
ultimately also come to an end, and what is to be done
then?

“We have not yet come to that pass,’ we hear those
exclaim, whose fields are still fertile and yield abundant
crops; “we are not yet come to that pass,” said also a
certain robber who was admonished to lead a better life,
until one fine morning he found the hangman’s rope around
his neck. ‘To that pass” it will alsorassuredly come at
last. with agriculturists. Their system may -be based on
agricultural experience, but it is certainly devoid of all
foundation i in science.

LETTER XII

Modern Agriculture has no history—The reason of this—The history of
Roman Agriculture shows the existence of the spoliation system at that
period—The works of Cato, Virgil, Varro, and Pliny inculcate, two thou-
sand years ago, the same precepts that are now taught by many teachers
of agriculture— Quotations from these writers, to show their opinions on
the exhaustion of the ground; on the different kinds of soils, and the
modes of improving them; on the selection of plants for the soils which
are suitable for them; on fallowing; on the cultivation of green crops for
manures; on the different kinds of manure and their relative values, and
modes of managing them—The various precepts inculecated of old only
hastened the ruin of Roman agriculture.

THE history of mankind, says 7'haer, is also the history
of agriculture. No saying can be further from the truth
than this. All our departments of industry having any
connection with the natural sciences have a history:
modern agriculture alone, has none; for it is a thing of
to-day, or, at the most, but of yesterday. What occurred
a week ago, it knows not; and if it is acquainted with it,
such knowledge does not make the agriculturist any wiser.

Facts by the million cannot be bequeathed ; but scientific
principles which are expressions for these facts, may be so,
because they are immutable in their nature.

Agriculture is, of all industrial pursuits, the richest in
facts, and the poorest in their comprehension. acts are
hike grains of sand which are moved by the wind, but
principles are these same grains cemented into rocks. A
fact simply tells us of its existence, but experience ought to
inform us why it exists.

Science is conservative in her nature, not destructive.
She does not reject the truths discovered by practice, but

188 THEORETICAL AND PRACTICAL AGRICULTURE.

receives them; they are never disputed by her, but are
examined and receive from her their proper import and
further application. Science, therefore, can produce no
revolution in practice; but she leads the way to a series of
progressive developments, which are evolved in natural
sequence from each other.

Modern agriculture has methods and working systems,
but it is altogether deficient in fixed principles and positive
knowledge. After so many thousand years, even our best-
mformed and most experienced agriculturists do not yet
know what kind of manure will answer best, or under what
circumstances fresh manure ought to be used in preference
to old, or vice versé!

Modern agriculture has, up to this time, no connection
with the history of the development of man; that history
is the mirror which reflects not only his errors and failures,
but also his onward progress. But modern agriculture
rejects the idea of ever being in error, and therefore she
knows nothing of progress.

If the history of the development and progress of the
human race really found a place in the study of modern
agriculture, or if teachers of that pursuit would only take
the trouble to make themselves acquainted with the pages
of that history, our agriculturists would know that, two
thousand years ago, the most enlightened and most eminent
men of ancient Rome already found the cultivation of the
soil beset by the same difficulties which threaten it to-day;
and that the same system of ‘high farming” which our
modern teachers now recommend as the best, was then
tried, and found wanting.

The following statements, taken from the writings of
Columella, Cato, Virgil, Varro, and Pliny, are calculated to
enlighten the agriculturist as to the actual point of “ pro-
gress” to which he has attained in the practice of his pur

THEORETICAL AND PRACTICAL AGRICULTURE. 189

suit; and to show him that his modern teacher, after all,
inculcates nothing that was not known to the world equally
well, and often even much better, two thousand years ago.
Reading the twelve books of Columella, after a perusal of
our modern manuals of practical agriculture, is just like
stepping from an arid and barren desert into a beautiful
garden—so fresh and charming does everything appear.

In his preface addressed to Publius Silvinus, Columella
says: ‘The Magnates of the state are in the habit of com-
plaining of the sterility of the land, or of the unsettled state
of the weather, which has now for a long time exerted an
unfavourable influence on the growth of agricultural pro-
duce; others are of opinion that the soil has been exhausted
by the over-productiveness of former years. But,” he con-
tinues, “no one gifted with common sense, will ever permit
himself to be persuaded that our earth has grown old, as
man grows old. ‘The sterility of our fields is to be imputed
to our own doings, because we hand over the cultivation
of them to the unreasoning management of ignorant and
unskilful slaves.

“The agriculturist requires one kind of knowledge, the
herdsman another. The former ought to know what pro-
duce will answer best for his land; the latter must under-
stand the most remunerative way of breeding cattle. Now,
as the two pursuits are most intimately connected with
each other, inasmuch as it is much more advantageous to
use the provender grown on the field for home consump-
tion, than to sell 1t; and as manuring mainly contributes
to make a field fertile, and cattle are principally kept for
the production of manure, therefore every body who owns
a farm must not only possess a knowledge of agriculture,
but also of pasturage, and of the process of stall-feeding.”
—(Columella.)

“Wherein does a good system of agriculture consist? In

190 THEORETICAL AND PRACTICAL AGRICULTURE.

the first place, in thorough ploughing; in the second
place, in thorough ploughing; and, in the third place, in
manuring.””—(Cato).

“Colour is no reliable sign of the good quality of a soil.
For as the strongest cattle exhibit an almost infinite variety
of colour, so is also the best land of many and divers
colours.”’—(Columella).

“There are many different sorts of soil; such as chalky,
sandy, clayey, &c. One soil is moist, another dry, or
moderately so; there are rich soils and poor soils, light
soils and heavy soils. By the intermixiure of these an
infinite variety is created. A stiff clay soil may be
improved by the addition of sand or marl; a sandy soil,
by the addition of clay.”—(Pliny, Pallad. Col.)

‘“‘Superfluous moisture must be drawn off by ditches,
either open or covered; in a chalky and stiff ground open
ditches are preferable. Open ditches must be wider at the
top than at the bottom; if they are of the same width
throughout, the sides are undermined by water, and the
falling earth fills up the ditch. Covered ditches are dug to
the depth of three feet, half filled with small stones or
coarse gravel, and the earth dug out is then thrown over
the top and levelled. If neither gravel nor stones are to
be got, then as many bundles of brushwood are thrown in
as the narrow ditch will hold, and the whole is covered
with earth. At the openings of the ditch, two stones are
placed upright, as pillars, to support a third, like a small
bridge; this keeps the ditch open.’”’—(Col.)

“A soil to be fertile must, above all things, be light and
friable, and this condition we seek to bring about by the
operation of ploughing.”—(Virgil).

‘ Ploughing the land simply means rendering the earth
porous and friable, which most tends to increase its produc-
tiveness.” —(Cato.)

THEORETICAL AND PRACTICAL AGRICULTURE. 191

“The ancient Romans held, that a field which required
harrowing could not have been well ploughed.”—(Colu-
mella.)

‘A heavy soil should be turned up in autumn, and
ploughed three times, and the furrows be multiplied and
drawn so closely together, that it may be barely possible to
distinguish from which side the plough has proceeded ;
for by these means weeds are thoroughly rooted out.
Fallow land must be ploughed until it is almost reduced to
powder. The owner of a farm should often ascertain for
himself whether itis properly ploughed. or this purpose,
he need simply thrust a staff-through the furrows (the
Romans laid out their fields in broad undulating ridges, as
may still be seen at the present day in the neighbourhood of
Nuremberg; only the Roman ridges were much broader);
if the staff passes through unresisted, it 1s a sure sign that
the soil has been properly ploughed. Care must be taken
to break clods of earth. Fields should be ploughed when
neither too dry nor too wet; if the soil is too hard, the
plough will not penetrate, or it will simply tear off large
clods. Even the best soil is unfruitful in its deeper layers,
and the large lumps of earth torn up by the plough bring
part of this subsoil to the top, which tends to deteriorate
the arable surface soil. Always select for your fields those
plants that may be best suited to their positions” (Cato) ;
“for all plants will not thrive equally well in all sorts of
soils.’—(Varro). ‘Some plants require a dry soil, others
thrive best in moist ground.”—(Col.) ‘‘ Naturally moist
eround answers best for pasturage.”—(Cato). ‘‘ Hay grown
on naturally moist ground is better than where its produc:
tion has to be stimulated by irrigation. A meadow plot in
a plain must have a slight fall, that rain and other water
may not gather on it in pools, but gently flow off’—
(Col). The seeds intended for sowing should be picked

192 THEORETICAL AND PRACTICAL AGRICULTURE.

out by hand, and pulse be previously soaked in saltpetre
water :—

“Still will the seeds, tho’ chos’n with toilsome pains
Degenerate, if man’s industrious hand
Cull not each year the largest and the best.
Tis thus by destiny, all things decay
And retrograde, with motion unperceived.”
Kennedy’s Virgil’s Georg.

“Take care to have your corn weeded twice with the hoe,
and also by hand.”—(Cato).

‘‘On large estates fields are alternately allowed to lie fal-
low in order to save manure.”’—(Pliny). ‘“ Where want of
space forbids this, green crops are grown alternately with
cereals, and the loss of productive energy is restored by
manuring.”—(Cato, Columella). ‘Some agriculturists grow
cereals on their fields two years in succession; proprietors,
however, forbid this to their tenants.”—(Festus). “The land
must rest every second year, or be sown with lighter kinds
of seeds, which prove less exhausting to the soil.” —(Varro).

“Of the leguminous plants, lupines first deserve our
attention, because they require the least labour, are cheap-
est, and of all seeds are the most profitable for the land;
they give the best manure for impoverished fields, and will
grow on a Sterile soil.

“Some of the leguminous plants manure the soil according
to Saserna, and make it fruitful, whilst others exhaust it, and
make it barren. Lupines, beans, peas, lentils, vetches are
reported to manure the land. Of lupines and vetches I
believe this to be truly the case, provided they be cut down
green, and ploughed in before they are dry.”—(Columella).
‘“Tjinseed, poppy, and oats exhaust the soil.” —(Virgil).
‘Hor fields that have suffered from the cultivation of these
plants, manuring is the only efficacious means by which the

THEORETICAL AND PRACTICAL AGRICULTURE. 193

lost productive energy of the earth is restored.” —(Columella).
“There are three kinds of manure: the best is the excrement
of birds; then comes that of man; and lastly, that of cattle.
The last also varies in quality. Asses’ dung is the best;
then follow sheep’s dung, and that of goats, horses, and
cattle; the least efficacious of all is the dung of swine.
Where an estate consists altogether of corn-fields, there is
no need to put on every kind of manure separately; but
where there are plantations of trees, arable land, and pas-
turage, every kind of manure should be applied separately.”
—(Columella). “ Pigeons’ dung (guano) should be spread
on meadows and gardens, or over the seeds.”—Cato, Varro,
Cassius). ‘“ Horse-dung is about the best suited for meadow
land, and so in general is that of beasts of burthen fed on
barley; for manure produced from this cereal makes the
grass grow luxuriantly.”—(Varro).

‘“‘ Ash also is used with advantage on fields; and on the
other side of the Po,” says Pliny, “the use of ash is viewed
so favourably by farmers, that they actually prefer it to the
manure furnished by their cattle. Should there be no kind
of manure at hand, the example of my paternal uncle, M.
Columella, may be followed with advantage; he would not
manure his vineyard, as he was of opinion that this tended to
impair the fine flavour of the wine; but he applied a layer of
artificial mould, or earth brought from the woods, and made
sure of obtaining by this means a more abundant vintage.
Where no kind of manure is to be had, I think the cultiva-
tion of lupines will be found the readiest and best substitute.
If they are sown about the middle of September in a poor
soil, and then ploughed in, they will answer as well as the
best manure.”—(Columella).

“ Acriculturists ought to know that a field will indeed
lose its productive power when left altogether unmanured ;
but that, on the other hand, over-manuring is also very

9

194 THEORETICAL AND PRACTICAL AGRICULTURE.

prejudicial. Let farmers, therefore, manure vheir fields
often, rather than over much at a time.”—(Columella).

‘‘T have here one more remark to add, namely; that
manure is best suited for the field when it is a year old.
In summer it ought to be turned up and always kept moist,
in order that the seeds of noxious weeds in it be rotted, and
be not again returned to the land.”—(Col.)

“The best fodder plants are lucerne, fenugreek (Menum
grecum), and vetches. Lucerne may be placed in the
foremost rank of such plants; for when it is once sown, it
lasts ten years, fattens lean cattle, and has a salutary action
on sick cattle. It must be carefully weeded at first, lest
the weeds choke the tender lucerne.”—(Columbella).

“A field is not sown entirely for the crop which is to be
obtained the same year, but partly for the effect to be pro-
duced in the following; because there are many plants
which, when cut down and left on the land, improve the
soil. Thus, lupines, for instance, are ploughed into a poor
soil, in lieu of manure.’”’—(Varro.) ‘‘ Mow your hay at the
proper season, and take care not to be too late with it; you
must cut it before the seed ripens, and store the best hay
separately.”—(Cato.) ‘‘ Mossy meadows may be improved
by a fresh sowing, or by manuring; but neither of these
operations will answer so well as frequent strewing with
ash, which destroys the moss.’’—(Columella.)

All these rules had, as history tells us, only a temporary
effect; they hastened the decay of Roman agriculture; and
the small farmer ultimately found that he had exhausted all
his expedients to keep his fields fruitful, and reap remune-
rative crops from them. Even in Columella’s time, the
produce of the land was only fourfold. The fields fell into
the hands of the large landed proprietors, who, by employ-
ing a multitude of slaves, were for a time enabled to obtain
“the largest crops at the least expenditure of manure.”

THEORETICAL AND PRACTICAL AGRICULTURE. 195

Even by these means the land was in the end not able to
bear the heavy taxation; and, as the history of the first
three centuries of our era informs us, there ensued a con-
dition of the population, the most calamitous and frightful
into which a nation can fall. It is true that many causes
co-operated in producing this result, but assuredly one of
these was the exhaustion of the soil by the spoliation sys-
tem of agriculture then pursued.

LETTER XIU.

The true object to be kept in view in establishing Scientific Principles—In
scientific agriculture, “‘ Manure,” like the term “ Phlogiston,” has no longer
a meaning—The cultivation of Green Crops for the purpose of keeping a
stock of Cattle for manure is not necessary in the cultivation of land—The
distinction between the Necessity and the Utility of keeping cattle—No
necessary connection exists between the production of Corn, and that of
Flesh and Cheese—The fundamental principles of German Agriculture
quite unknown in China—Chinese Agriculture—The manures employed
by them—Great value set by Chinese on human excrements; their mode
of collecting and using them—Chinese compost—Their mode of sowing
and transplanting wheat—Plants cultivated as green manure for rice fields
—The lesson taught by the Chinese system of agriculture.

I witu show the teachers of agriculture another people,
who, without the aid of science, of which they know
nothing, have found the philosopher’s stone, which these
very teachers, in their blindness, vainly seek. I will point
out to them a land, the fertility of which has for three
thousand years never decreased, but, on the contrary, has
been ever on the increase; and where more men are
crowded together on a square mile than are to be found on
the same space in Holland or England.

According to the testimony of all reports of our own
and former times, made by Davis, Hedde, Fortune, and
others, and which have been fully borne out by the
special inquiries into the state of Chinese husbandry, insti-
tuted on the spot at my request, by the direction of the
late Sir Robert Peel, it appears that in China, nothing is
known of meadow culture, or of fodder plants, which are
grown for the sake of cattle. Farm-yard manure 1s equally

THEORETICAL AND PRACTICAL AGRICULTURE. 197

unknown; every field yields produce twice a year, and is
never allowed to he fallow.

Wheat often produces one hundred and twenty fold
and upwards (Kckeberg); and a fifteen-fold crop is con-
sidered an average yield (Davis). All those means which
the German teacher of agriculture regards as indispensable
for increasing the produce of our fields, and instructs his
followers to employ, are not only entirely dispensed with by
the Chinese farmer, but he actually obtains, without their
co-operation, crops which exceed more than two-fold those
-of the German high farmers.

I readily admit that the Chinese are differently circum-
stanced from what we are in Europe. Most of them are
Buddhists, and eat no beef; we eat more flesh, and must
consequently grow fodder for the production of that article
of our diet. But that is not the question before us, but one
which concerns those principles that are to guide the prac-
tice of husbandry. Our teachers of modern agriculture
do not tell us to grow fodder that flesh may be produced ;
but that we ought to do so for the purpose of forming
manure; which clearly shows that they have no just con-
ception of the true nature and aim of agriculture, and that
they are altogether ignorant of scientific principles in the
matter.

In laying down a scientific principle, the first point for
consideration is not whether the application of it will turn
out profitable or not; but whether it is ¢rue; for if it is a
true principle, it must prove advantageous.

In scientific agriculture ‘manure’ finds no longer a
place; for the notions that were formerly attached to the
term are completely obsolete; just as is the case with the
word Phlogiston, which, up to the end of last century, was
~ used to explain chemical phenomena.

So long as the nature of Phlogiston was unknown, that

198 THEORETICAL AND PRACTICAL AGRICULTURE.

word served as a collective term to connect togetler, in an
intelligible form, a number of wnknown operating causes ;
but when it had once been settled what “‘ Phlogiston” really
meant and represented, the term had to give way to more
correct ideas; and interpretations of phenomena became
what they had never been before, viz. real and trustworthy.
Wood does not, on that account, burn differently now-a-
days from what it formerly did; the air played the same
part in its combustion then as now; and water still possesses
the same property of making bodies wet; but what immense
progress has been made by mankind, as the result of sub--
stituting for the word “ Phlogiston,” the proper conceptions
of the nature of air, of oxygen, and of the process of com-
bustion |!

A similar progress, but much more important, and infi-
nitely more beneficial to man, will spring from a correct
apprehension of the process of nutrition in plants and
animals. Absurd as would now be the attempt of a teacher
of Chemistry to account for any chemical process by having
recourse to phlogiston, it is no less inadmissible in a teacher
of scientific agriculture to explain a given fact by attribut-
ing it to “manure ;” for, in the place of the obsolete notion
of “manure,” which has no longer any meaning, we have
now for every plant certain positively known elements of
food, to the united action of which we have to look for an
explanation of the fact or phenomenon in question.

The doctrine which inculeates as necessary for the cul-
tivation of the land, the production of manure by green
crops, and along with this the maintenance of a stock of
cattle, 1s erroneous,

It is necessary here to distinguish between necessity and
utility. A stock of cattle may prove very useful to the
farmer, and yield him a remunerative return in butter,
cheese, and meat; but this is quite a distinct affair from the

THEORETICAL AND PRACTICAL AGRICULTURE. 199

tillage of his fields, and he ought to know, and must be
taught, that there is absolutely no compulsion upon him to
keep a stock of cattle.

The keeping of cattle is necessary for the production of
manure ; but the production of manure ts by no means neces-
sary for the fertilisation of corn fields. In the system of the
rotation of crops, all that ws required its that green crops
should be grown, and that their constituent parts be incor-
porated with the arable surface soil of the field; and it is
quite immaterial for the cereals whether the green crops be
previously eaten by the cattle and converted into manure or
not.

If lupines, vetches, clover, turnips, &c., are cut up and
ploughed in, in the green state, their action is far more
powerful.

There is no natural connection of mutual dependence
between the production of corn and that of flesh and cheese;
on the contrary, they interfere with each other, and must
in science be considered as perfectly distinct and separate
things; for the production and sale of flesh is carried on at
the expense of grain, and vice versd. We cannot do with-
out meat, milk, or cheese; and if the production of these
articles be left entirely to the grazier, who, on his part, ought
to meddle as little as possible with the growing of grain,
both he and the farmer, as well as the consumer, would
profit by it. In England this separation of the two pur-
suits is gradually gaining ground; and when, as is to be
. hoped, our German farmer shall have succeeded, in the
course of time, in mastering the multiplication table, we
may expect that the same separation will take place in
Germany. Chemical manufactories are not established any-
where and everywhere, but only in localities offering cer-
tain natural advantages; and Agriculture, after all, is
simply an industrial pursuit, like any other.

200 THEORETICAL AND PRACTICAL AGRICULTURE.

In China they know nothing of the fundamental prin-
ciples upon which German agriculture is based. Except
ereen manuring, they neither know nor esteem the applica-
tion of any kind of manure beyond the excrements of man.
The other matters occasionally employed by them to in-
crease their crops, are In quantity and effect utterly in-
significant, when compared with the use of human excre-
ments.

It is quite impossible for us in Europe to form an ade-
quate conception of the great care which is bestowed in
China upon the collection of human excrements. In the
eyes of the Chinese, these constitute the true sustenance of
the soil (so Davis, Fortune, Hedde, and others tell us), and
it is principally to this most energetic agent that they
ascribe the activity and fertility of the earth.

The Chinese, whose house is still, what it most probably
has ever been, a tent, only that it is built of stone and
wood, knows nothing of privies as we have them in our
country ; but, in their stead, there are found in the princi-
pal and most comfortable part of his dwelling, earthenware
tubs, or cisterns most carefully constructed of stone and
lime; and the notion of utility so completely prevails over
the sense of smell, that, as Fortune tells us (‘The Tea Dis-
tricts of China and India,” vol. i., p. 221), “ what in every
civilised town of Kurope would be regarded as a most in-
tolerable nuisance, is there looked upon by all classes, rich
and poor, with the utmost complacency, and,” he continues,
‘nothing would cause greater surprise to a Chinese than to
complain of the stench arising from these receptacles.”
The Chinese do not disinfect this manure; but they are
perfectly aware that it loses part of its fertilising power by
the action of the air; and they, therefore, take great care
to guard against evaporation.

Except the trade in grain, and in articles of food, gene-

THEORETICAL AND PRACTICAL AGRICULTURE. 201

rally, there is none so extensively carried on in China as
that in human excrements. Long clumsy boats, which
traverse the street canals, collect these matters every day,
and distribute them over the country. Every Coolie who
has brought his produce to market in the morning, carries
home at night two pails full of this manure on a bamboo
pole. |

The estimation in which it is held is so great, that every-
body knows the amount of excrements voided per man in
a day, month, or year; and a Chinese would regard as a
gross breach of manners the departure from his house of a
guest who neglects to let him have that advantage to which
he deems himself justly entitled in return for his hospitality.
The value of the excrements of five people is estimated at
two Teu per day, which makes 2000 Cash* per annum, or
about twenty hectolitres (440 galls.), at a price of seven
florins.

In the vicinity of large towns, these excrements are con-
verted into poudrette, which is then sent to the most distant
places, in the shape of square cakes, like bricks. For use,
these cakes are soaked in water, and applied in the fluid
form. With the exception of his rice fields, the Chinese
does not manure the field, but the plant.

Every substance derived from plants and animals is care-
fully collected by the Chinese and converted into manure.
Oil cakes, horn, and bones, are highly valued, and so is
soot, and more especially ash. ‘'T'o give some notion of the
value set by them upon animal offal, it will be sufficient to
mention that the barbers most carefully collect, and sell as
an article of trade, the somewhat considerable amount of
hair of the beards and heads of the hundreds of millions
of custi mers whom they daily shave. The Chinese know

* 100 Cash are equal to about 44d. (Fortune).
Q*

202 THEORETICAL AND PRACTICAL AGRICULTURE.

the action of gypsum and lime; and it often happens that
they renew the plastering of the kitchens, for the purpose
of making use of the old matter for manure.—(Davis.)

No Chinese farmer ever sows a seed of corn before it has
been soaked in liquid manure diluted with water, and has
begun to germinate; and experience has taught him (so he
asserts), that this operation not only tends to promote the
growth and development of the plant, but also tc protect
the seed from the insects hidden in the ground.—(Davis.)

During the summer months, all kinds of vegetable refuse
are mixed with turf, straw, grass, peat, weeds, and earth,
collected into heaps, and when quite dry, set on fire; after
several days of slow combustion, the entire mass is converted
into a kind of black earth. This compost is only employed
for the manuring of seeds. When seed time arrives, one
man makes holes in the ground; another follows with the
seed, which he places in the holes; and a third adds this
black earth. The young seed planted in this manner grows
with such extraordinary vigour that it is thereby enabled
to push its rootlets through the hard solid soil, and to col-
lect its mineral constituents.—(Fortune.)

‘The Chinese farmer sows his wheat, after the grains
have been soaked in liquid manure, quite close in seed-
beds, and afterwards transplants it. Occasionally, also, the
soaked grains are immediately sown in the field properly
prepared for their reception, at an interval of four inches
from each other. The time of transplanting is towards the
month of December. In March the seed sends up from
seven to nine stalks with ears, but the straw is shorter than
with us. I have been told that wheat yields 120 fold and
more, which amply repays the care and labour bestowed
upon it.”—(Hckeberg, Report to the Academy of Sciences
at Stockholm, 1765.)*

* The Dresden Journal, of 16th September, 1856, contains the follow-

THEORETICAL AND PRACTICAL AGRICULTURE. 203

In Chusan, and the entire rice districts of Chekiang and
Keangsoo, two plants are exclusively cultivated for the
purpose of serving as green manure for the rice fields; the
one is a species of Coronilla, clover is the other. Broad
furrows, similar to those intended for celery, are made, and
the seeds are planted on the ridges in patches, at a dis-
tance of five inches from each other. In the course of a
few days germination begins, and long before the winter is-
gone, the entire field is covered with a luxuriant vegeta-
tion. In April the plants are ploughed in; and decompo-
sition soon begins, attended with a most disagreeable odour.
This method is adopted in all places where rice is grown.—
(Fortune, vol 1, p. 238).

These extracts, which, from want of space, cannot be
further. extended, will probably suffice to convince the
German agriculturist, that his practice, when compared
with that of the oldest agricultural nation in the world,
stands somewhat in the position of the acts of a child to
those of a full grown and experienced man. The Chinese
system of husbandry is the more remarkable, if we take

~

ing statement:—‘“ As we are informed from EHibenstock, forest-inspector
Thiersch, of that place, has for several years past made very successful
experiments in transplanting winter corn in the autumn. He transplanted
the young plants intended for the purpose in the middle of the month of
October, one peck of seed-corn to one hundred square rods of ground, which
produced an uncommonly rich crop. There were roots from which sprung
as many as fifty-one stalks with ears, and the latter contained as many as
one hundred grains.”

I have applied to Mr. F. J. Thiersch for more precise details of his experi-
ments; and from his statement as to the cost of the operation and the
return made, there appears to be no doubt that the Chinese mode of hus-
bandry might also be resorted to with advantage in Europe, in localities
where the land is rich and labour abundant. One of my friends, who visited
' M. Thiersch’s experimental field, told me that he had counted twenty-one
stalks with full ears on a plant pulled up at hazard (not picked out). For
poor fields this method of cultivation is entirely unsuited.

204 THEORETICAL AND PRACTICAL AGRICULTURE.

into account what they have achieved in other mechanical
and chemical pursuits, more incomprehensible, as they owe
everything to the purest empiricism. For the Chinese
system of instruction has, for thousands of years, so
thoroughly excluded every inquiry after an ultimate cause
of things, which might possibly have led to the discovery
of scientific principles, or to the establishment of a science,
that the capability of making further progress, except by
imitation, would seem to be destroyed to the very root in
that people. The study of the physical laws, which has
led European nations to the invention of the steam-engine,
and of the electric-telegraph, and has enabled man to con-
trol and turn to his account the forces of nature in number-
less other instances, is a matter of absolute impossibility to
the Chinese scholar. It is the express command of their
first and most ancient teacher of religion, Confucius, that
the student shall never allow any thought to rise in his
mind but such as he finds written in his books.

It is quite true that what suits one people may not on
that account suit all countries and all nations; but one
great and incontrovertible truth may, at all events, be
learned from Chinese agriculture, viz., that the fields of
the Chinese cultivator have preserved their fertility unim-
paired, and in continued vigour ever since the days of
Abraham, and of the building of the first Pyramid in
Egypt.* This result we also learn has been attained solely
and simply by the restitution to the soil of the mineral con-
stituents removed in the produce; or what amounts to the
same thing, that this has been effected by the aid of a ma-
nure, of which the greater portion is lost to the land in the
Kuropean system of cultivation.

* Vessels of Chinese porcelain are found in the Pyramids, of the same
shape, and with the same characters of writing on them, as are made in
China at the present day.

LETTER XIV.

The law of Compensation is of universal application—Elementary information
on Chemical subjects connected with Agriculture easily imparted—Im-
portance of instructing youth at school in these fundamental truths—Theo-
retical instructions should always precede Practical—The proper mode of
instructing agriculturists in the Theory and Practice of Agriculture—The
present constitution of Agricultural institutions very defective—The false
position of Science in practical agriculture is the result of the teachings of
these Schools—The demands made by Science on agriculturists are simple,
and a knowledge of them cannot prove injurious—Science demands that
agriculturists should test the Truths she advances—The truths in these
Letters expressed by a Formula—The value of Guano first discovered by
Science—The establishment of Reservoirs for animal excreta strongly
recommended— Reliance to be placed upon such Excreta rather than on
Guano—Chemistry can only help agriculturists after they have exhausted
all the means at their disposal—Notes on supply of guano and on the
agriculture of Tuscany.

THE Kuropean husbandman has, for centuries past, been
in the habit of taking away the produce of his fields, with-
out making compensation for the mineral matters removed,
and his fields have accordingly been continually diminish-
ing in fertility.

The Chinese husbandman has, for thousands of years
past, made it a practice to restore to his fields the mineral
constituents removed from them in the produce, and the
fertility of his land has accordingly kept pace with the in-
crease of the population.

The law of compensation, which makes the recurrence
or permanency of effects dependent upon the recurrence or
permanency of the conditions which produce them, is the
most universal of the laws of nature; it governs all natural

206 THEORETICAL AND PRACTICAL AGRICULTURE.

phenomena in their various phases, all organic processes,
all the productions of man’s industry. That the agricultu-
rist alone should ignore this law, nay, that his teachers and
guides should actually deny its operation, shows clearly
the condition of the schools in which the sons of our far-
mers are taught.

What Chemistry teaches about air, water, the process of
combustion, arable soil, the ash of plants, manure and its
constituents, is so easy of comprehension, that every well-
informed teacher may, in a dozen lessons, and with the sim-
plest means of instruction, impart to the commonest peasant
boy an accurate knowledge of these things; particularly if
the teacher strictly confine himself to his subject. The lec-
tures occasionally delivered on matters of this nature at the
Royal Institution of London, by Professor Faraday, before
an audience of children, may be adduced in proof that it
is quite practicable to do so.

By command of King Maximilian, a movement in this’
direction has of late been made in Bavaria. Five years
ago, all the teachers of the schools for training schoolmasters
were, for this purpose, specially instructed and exercised in
Munich.

The diffusion of this elementary knowledge among the
peasantry through the agency of the schoolmaster, will be
an immense step in advance, and will prove the very best
thing that the state can do in the interest of agriculture.

The boy who has been taught at school, even though
superficially, the conditions on which the fertility of the
field depends, and who has been told by his teacher, that
he who uselessly wastes these conditions is guilty of an
offence against the poor, against himself, and against society,
will certainly, when he grows up to man’s estate, construct
receptacles for human and animal excrements, such as no
police regulations could ever compel him to provide.

THEORETICAL AND PRACTICAL AGRICULTURE. 207 |

A superficial examination of the system prevailing in the
higher agricultural institutions, is sufficient to convince us,
that, such as they are at present, they are totally unsuited
for the requirements of our day.

The combination of the ordinary arrangements of a
school, with instructions in the practical work of agricul-
ture, does away with the benefits which might be derived
from such institutions, which are neither one thing nor an-
other; they are neither educational institutions nor good
practical workshops; they possess some of the features of
both, but none of the good points of either.

The technical part of an industrial pursuit can be |)
learned; principles alone can be taught. To learn the trade | |
of husbandry, the agriculturist must serve an apprentice- |
ship to it; to inform his mind in the principles of the
science, he must frequent a school specially devoted to this } /
object.

It is impossible to combine the two; the only practicable
way is to take them up successively. I formerly conducted
at Giessen a school for practical chemistry, analysis, and
other branches connected therewith, and thirty years’ expe-
rience has taught me that nothing is to be gained by the
combination of theoretical with practical instruction. A
student of chemistry who attends the lecture-hall and the
laboratory concurrently, positively defeats thereby the
object of his stay at the school, and misses the aim of his
studies. It is only after having gone through a complete
course of theoretical instruction in the lecture-hall that the
student can with advantage enter upon the practical part
of chemistry; he must bring with him into the laboratory
a thorough knowledge of the principles of the science, or
he cannot possibly understand the practical operations. If
he is ignorant of these principles, he has no business in the
laboratory. a !

208 THEORETICAL AND PRACTICAL AGRICULTURE.

In all industrial pursuits connected with the natural
sciences, in fact, in all pursuits not simply dependent on
manual dexterity, the development of the intellectual facul-
ties, by what may be termed “school learning,” constitutes
the basis and chief condition of progress and of every im-
provement. A young man, with a mind well-stored with
solid scientific acquirements, will, without difficulty or
effort, master the technical part of an industrial pursuit;
whereas, in general, an individual who may be thoroughly
master of the technical part, is altogether incapable of seiz-
ing upon any new fact that has not previously presented
itself to him, or of comprehending a scientific principle
and its application.

I have often found that students coming from good col-
leges will speedily leave the pupils of industrial and poly-
technic schools far behind them even in the natural sciences,
though the latter, when compared with the former, were at
first giants in knowledge.

I am far from wishing to question in any way the very
great utility of industrial and technical schools. I consider
them just as indispensable as higher schools; for the same
road is not suited to all men, and every one does not pos-
sess an aptitude for the study of languages. The minds
of youth may be compared to a variety of ores, requiring
different furnaces for the smelting and extraction of the
metal, and the removal of the slags. But talent is like
gold; wherever it occurs in nature it is found in its pure
state, never as an ore, and every furnace is equally suited
to it.

Tn our agricultural academies the training of the pupils
in the mechanical and technical branches is continually
interfering with their proper instruction in principles and
theories in the school. ‘Whenever a new sowing machine,
or a plough, or some other agricultural implement is to be

THEORETICAL AND PRACTICAL AGRICULTURE. 209

tried, the lecture-halls of Chemistry, Physics, &c., are
deserted. The greater portion of their teachers of Mathe-
matics and the Natural Sciences have received a university
education, and are, as may be expected, able scientific men,
but their teachings are held of secondary importance to the
practical work of husbandry; they become speedily dis-
couraged; and, under such circumstances, a solid course of
instruction in the natural sciences is out of the question.
I never yet met with one pupil trained at one of these insti-
tutions, who had a correct conception of the theory of dew,
or who was able to distinguish the seeds of the meadow
grasses, or the grasses themselves.

The learning of a technical pursuit is a different thing
from the acquirement of an art which demands practice.
The pupil of an academy of fine arts may see from day to
day what progress he has been making; and this gives him
the necessary encouragement, which again tends to stimulate
his ardour, and makes him persevere in his efforts. But the
pupil at an agricultural academy has no standard by which
to measure the progress he has been making in technical
knowledge; the incentive to exertion is wanting, and all
emulation ceases.

The young agriculturist who wishes to acquire a com-
petent knowledge, both theoretical and practical, of his pur-
suit, ought to visit, in the first place, a university to obtain
the necessary knowledge of the natural sciences, and after-
wards an agricultural institute, where the principles of
agriculture, and, at the same time, its practical operations,
are taught on a large scale.

Now, if we reflect that the majority of our agricultural
academies have, for a generation past, been conducted in a
-Imeasure by men who have no knowledge whatever of
Chemistry, Physics, Botany, Geognosy, &c., the conviction
forees itself upon the mind, that they have been much more

210 THEORETICAL AND PRACTICAL AGRICULTURE.

schools of idleness, and of opposition to all progress, than
institutions for advancement.

The conflict at present raging about the principles of
science and their application to practical husbandry, is the
work of these schools; and no one need wonder if the prac-
tical man should hold science in little respect, nay, if he
should regard it with positive contempt. For, whence can
this estimation and regard for science proceed, except from
a knowledge of its principles ?

I am ready and willing to retract every word I have
uttered against these institutious, if any one will solve, in
some other way, the enigma which the antagonism between
the precepts of science and the practical lessons of agriculture
presents. The former do not simply embrace the principles
at which a single individual has arrived; but they com-
prehend the general principles of all science. All chemists
and physicists, all students of nature and mathematicians,
entertain them, because they are simply expressions of that
method to which they all owe their success.

All practical men are agreed on this one point, that they
ought not to alter their practice on account of a doctrine,
however probable it may appear; they demand to be first
convineed of its truth, and then, as a matter of course, all
opposition on their part will cease. This condition would
be reasonable enough, were there anything in this doctrine
which might possibly prove injurious to their interests; but
their opposition is not directed against the doctrine, but
against common sense, and no science in the world can over-
come opposition of such a nature.

The scientific principles which chemistry wishes to in-
troduce into agriculture are so very simple, and the
demands made upon the practical husbandman are so much
to his own advantage, that, to an unprejudiced person, his
opposition is incomprehensible.

THEORETICAL AND PRACTICAL AGRICULTURE. 211

Science has taken upon herself to accomplish what was
beyond the power of practice, from its very nature, to do.
She has thoroughly examined the soil, the air, the excre-
ments of man and of animals, the roots and tubers of plants,
their leaves, stalks, seeds, and fruits, the blood and flesh of
animals; she has, in short, investigated everything of a
combustible and incombustible nature contained in organic
bodies, and which is of importance in their production.
The results of her researches and analyses she has laid
before the practical agriculturist, and has shown him that
plants, manures, and the sozl, have certain constituent ele-
ments in common. From the constant presence of these
constituent elements in plants, she has inferred that they
are indispensable to the formation of the plant and its parts
—an inference which naturally leads to the conclusion that
they are equally necessary in the soz in which the plants
are to grow, as well as in the manure which is intended to
aid their growth. Science has also demonstrated, still with
the balance in her hands, that even a soil regarded as
abounding in these constituent elements contains in reality
only a comparatively very small proportion of them.

Science demands from the practical agriculturist no more
than that he should acquire the very triflmg amount of
chemical information requisite to enable him to understand
the language of chemistry, and to test the correctness of
these facts. It would be absurd in the extreme to fancy
that this could in any way tend to interfere injuriously
with the practical operations of husbandry. She asks the
farmer to test the correctness of these facts in his own way ;
to prove by actual experiment, whether a field which does
not possess these constituent elements, is nevertheless a
fruitful soil for the production of cultivated plants; and if
not, whether it may be made fruitful by a proper supply of
these matters. She asks him further to try if a field

212 THEORETICAL AND PRACTICAL AGRICULTURE.

abounding in these elements is rendered barren by their
removal ffom it. Surely a trial of this kind cannot be said
to be of a nature likely to interfere injuriously with the
practical operations of husbandry.

When agriculturists have in this way acquired the con-
viction that the facts and inferences of chemistry agree
with the facts and results of the agricultural test applied,
everything has then been done that can be done by chemistry
for agriculture. The instructions given beyond this no
longer pertain exclusively to the domain of chemistry, but
are common to all sciences.

When, therefore, the agriculturist has, in the’ manner
just described, ascertained that the facts and inferences
advanced by chemistry are fully borne out by the results
of agricultural experience, it can surely only be to his own
advantage to shape his practice by her lessons, and to make
the necessary changes in those portions of his operations
which he finds have been founded in error. It is not che-
mistry alone, but common sense, and everything besides
connected with these facts, which require him to do this.
Common sense tells him that he ought to provide for his
fields a proper supply of these constituent elements, and
restore them where they have been taken away, if he wishes
to make a barren soil produce fruit, or increase the fertility
of a fruitful field, or keep a very fertile field constantly at
the same high degree of productiveness; it tells him that
the art of the agriculturist cannot simply consist in lower-
ing the high productiveness of a field to the level of ordi-
nary fertility, and in turning a fruitful ito a sterile field.

It is held as a fundamental principle in science, that
every opinion, before it is admitted as true and taught to
others, should first be established by proper proofs, which
must not in any way run counter to undoubted truths,
such as, for instance, that twice two are four, and not five.

THEORETICAL AND PRACTICAL AGRICULTURE. 213

Inferences and conclusions which are opposed to such
truths are rejected by science, and it cannot surely be con-
sidered an unreasonable request, to ask agriculturists to
adopt the same principle as a guide in drawing their con-
clusions. Now, it is actually upon these points that the
conflict turns; for the opposition is in reality directed, not
so much against the facts and teachings of chemistry, as
against the deductions drawn from them by common sense.

The exposition of the scientific principles of agriculture
is not a thing of yesterday, but dates so long ago as seven-
teen years; and the system of husbandry as taught in our
agricultural institutions (see Letter I.), could certainly not
have so long withstood the power of truth and common
sense, had it not been separated from them as if by a wall,
and defended from their attacks.

The chemical truths in these Letters may be expressed
by a simple formula, which, though bearing a somewhat
mathematical appearance, is yet plainly intelligible to every
one:

P=F—R.

The P in this formula stands for Produce (Corn, Pota-
toes, Turnips, &c.); the F. stands for Food (Phosphoric
acid, Potash, Lime, Ammonia, &c.); the R stands for Re-
sistance.

Expressed in words the formula stands thus:

The amount of produce yielded by a field corresponds
with, or is proportionate to the quantity of food in the soil
(to the conditions for the production of the crop), minus
the sum of the resisting forces which hinder the production
of the crop from the elements of food present. Let the
letter F stand for. six slices of an apple, and the letter R
represent three fingers keeping a firm hold on two out of
the six slices, there will remain only four slices free, which
may be eaten by another person.

214 THEORETICAL AND PRACTICAL AGRICULTURE.

The entire contents of these Letters are simply a develop-
ment of this formula. Everything that is said in them
about amount and increase of produce, fertility, cultivation
of the soil, manure, &c., is comprised in it. It is evident
that if the formula be true, its application will embrace
millions of receipts for the improvement of millions of
fields, and for the continued production of the largest
crops; and that the future prospects of our fields, and
wealth and income of all agriculturists, will be dependent
upon its strict and rational application. No one can then
deny, that the development of this formula is of some im-
portance to agriculturists, and its discussion of some value
to them.

Whatever progress has been made by practical agricul-
ture for some thousands of years past in the knowledge of
manures, is clearly referable to those true principles which
constitute the basis and conditions for correct conclusions.

Guided by a careful study of the elements of the food
of plants, science, in the year 1840, pointed out to the
} agriculturist guano as one of the most infallible means of
raising the produce of corn and flesh, and most urgently
recommended its application. Before 1840, guano had
never been used as manure on a Huropean field. When
the first vessel loaded with guano arrived at Liverpool,
numerous experiments were made with the new manure,
which proved failures; and agriculturists were not agreed
about its utility until they had practically tested its use.
Since that time many hundreds of ships have passed to and
fro, and have brought to the Huropean Continent guano to
the value of above 300,000,000 florins (£25,000,000); and
within the same period there has been produced a surplus
of more than 400,000,000 cwt. of corn, or of its equivalent
in flesh. It is true, guano would have found its way to
Europe even without the recommendation of science; for

THEORETICAL AND PRACTICAL AGRICULTURE. 215

a kind Providence makes the apple ripen in proper season,
and if it drops from the tree and rots, the fault lies with
man, or with the soil, if the seeds do not germinate. But
guano would probably not have made its way so speedily.
In the late seasons of sterility through which we have
passed, it has been the means of alleviating the wants of
many millions of men.

The man of theory who predicted the effects of guano
had not seen the favourable results of its application, which
our “ Nitrogen champions” had subsequently occasion to
observe in England; but the predictions of its utility had
been simply based on the results of its chemical analysis,
and was only a corollary deduced from the principle, that
it us indispensable to restore to the field exhausted by the growth
of corn the mineral elements taken away in the crops.

Not pseudo-chemistry, but science, placed in the hands
of the agriculturist the means of making phosphate of lime
more readily available for the nutrition of plants, by treat-
ment with sulphuric acid; and the results of the practice in
England for the last ten years have shown, that by the use
of this means the amount of provender for cattle has been
increased to the same extent as if the area of every field for
green crops had been doubled. There have been produced
since then, on the same area, many million cwt. more flesh
than formerly, or its equivalent in corn.

And the man of theory who advised the use of this
means had not seen its effects, as our agricultural chemists
in England have seen them; but he had simply inferred
them from the principle, that the action of a manuring agent
na given time must increase in proportion as us surface in-
creases.

Whatever practical agriculturists'and agricultural socie-
ties may do, whatever they may resolve at their annual
meetings, every penny spent will be thrown away, and

216 THEORETICAL AND PRACTICAL AGRICULTURE.

every year of experimenting will be in vain, so long as
these practical men will not submit to the teachings of true
experience, to the rules of logic or of common sense: from
the instant they shall so submit, science will be theirs.

There exists a receipt for insuring the fertility of our
fields and the permanence of their crops, and which, if pro-
perly and consistently applied, will prove more remunera-
tive than all the expedients that have ever before been
resorted to by agriculturists. It consists in the following
rule:

Every farmer who takes a sack of corn, or a cwt. of rape,
turnips, potatoes, &c., to the town, ought, like the Chinese
coolie, to carry back with him from the town an equal (or,
if possible, a larger) quantity of the mineral constituents of
the produce sold, and restore them to the field from which
they have been taken. He should not despise the peel of a
potato, nor a straw, but always bear in mind that that peel
may be wanting to form one of his potatoes, that straw to
form one of his ears of corn. The cost of carrying these
matters to his fields is trifling, and the investment is as
safe as a savings-bank, and highly productive withal. The
fertile area of his field will, in the course of ten years, be as
it were doubled; he will produce more corn, more flesh,
and more cheese, without having, on that account, to
bestow greater labour and time upon the cultivation of his
land ; he will be less anxious about his fields, and need no
longer keep his mind constantly on the stretch for some
new, unknown, and imaginary expedient to preserve their
fertility in some other way.

All the proprietors of the soil in every great country
ought to form a society for the establishment of reservoirs
where the excreta of men and animals might be collected,
and converted into a portable form. Bones, soot, ashes,
lixiviated and unlixiviated, the blood of animals, and offal

THEORETICAL AND PRACTICAL AGRICULTURE. 217

and refuse of all kinds, ought to be collected together in
these establishments, and prepared for transport by the
society’s own Officials.

To render the execution of a plan of this kind possible,
government and the police authorities should take measures
to insure the proper construction of latrines and sewers in
towns, to guard against the waste of the night-soil, &c.*
This must of course be a preliminary arrangement; but,
when once made, an annual subscription of half-a-florin
from every farmer, every peasant in the land, will suffice to
call into existence establishments of this kind in every
town; and there can be no doubt that these establishments
will speedily become self-supporting, if every agriculturist
will only make up his mind to act strictly upon the advice
here given.

Agriculturists must not rely upon guano; its price at the
present time, as compared with an earlier period, is already
doubled ; and no sensible man would entertain the idea of
making the production of an entire country dependent on
the supply of a foreign manure.t

* Judicious arrangements have already been adopted last year in Munich,
by the Minister of the Interior, with a view to the improvement of the: sani-
tary condition of the city. The success of these measures will materially
depend upon the manner in which the proprietors of the houses appreciate
and aid the wise intentions of government.

+ It is almost to be feared that guano will play a momentous part in his-
tory. When it is considered that one cwt. of that manuring agent contains
the effective mineral constituents of between 25 cwt. and 30 cwt. of wheat,
or of an equivalent amount of some other produce, and that, when used as
manure, it produces, in a succession of crops, a corresponding quantity of
elements of food, some conception may be formed of the immense value
which the guano beds of America possess, with reference to the production
of corn in Europe. From the enormous increase of the population of Lon-
don, and other large cities of Great Britain, the loss which the English fields
sustain annually in the main conditions of their fertility, is every year becom-
ing more and more considerable; and it would appear that the obstacles

10

218 THEORETICAL AND PRACTICAL AGRICULTURE.

Agriculturists must in the first place learn to turn to the
best account all the means and resources at their command ;
when they have done this, but not till then, will chemistry
be able to do them good and useful service. But so long
as they expect this science to present them with potent
charms for fertility, there is no help for them. They must
bear in mind, that wherever success does not attend a good
cause, the fault lies in want of energy in using the proper
means ; for these are always to be found.*

which oppose the collection of the human and animal excrements are alto-
gether insurmountable, at least as regards London. It is evident, therefore,
that England, in order to remain permanently a corn-growing country,
requires a free and plentiful supply of guano (even now Great Britain con-
sumes nearly nine-tenths of all the guano brought to Kurope). Fifteen
years ago the American agriculturists looked down upon guano with a
species of contempt; but things have greatly altered since then; and it is
said that Iast year about eight million cwt. of that manuring agent were
imported into the United States. In the actual position of English Agricul-
ture, America, by her guano-beds, rules the prices of all the corn-markets of
Europe, and more especially in England; and should circumstances ever
arise to prevent the importation of guano into England, a state of things
would ensue in that country of which the consequences might be
incalculable. Bloody wars have sometimes sprung from causes of much less
importance.

* If we ask the opinions of different persons on the question of “‘ sewage,”
we receive contradictory answers. All manufacturers of super-phosphate of
lime are quite agreed on the point, that only the fluid portions of sewage, or
the matters dissolved in sewage water, are valuable in agriculture. They do
not, in giving this opinion, deny the good effect of the solid matters, but only
mean to say that they are not worth the trouble of being eollected for
manure, because they are ready to deliver from their manufactories these
matters to agriculturists. The manufacturers of ammonia salts, and the
dealers in guano, take an entirely opposite view. These hold that only the
solid sewage matters are to be looked upon as important. There can, how-
ever, be no doubt that both the fluid and solid matters are valuable for
agriculture,

“The use of these fertilising matters is not confined to the estates and farms
in the immediate vicinity of the centres of population and consumption. Our
peasants go long journeys with their wretched carts to seek substitutes for

THEORETICAL AND PRACTICAL AGRICULTURE. 219

the deficient quantity of their farm-yard manure. The industrious peasant
of Lucca is worthy of ranking with the Chinese coolie. Enjoying the bless-
ings of irrigation within a circle of twenty-eight miles (English), the former,
who has never even heard of the name of guano, manages to reap two crops
in the year; and yet never allows his land to lie fallow. He goes, however,
with his cart, not only to the neighbouring town of Lucca, but even as far as
Pisa and Leghorn, to collect the contents of the sewers, with the aid of which
he produces, by indefatigable labour, marvellous crops, and raises food suffi-
cient for the most dense population of the old duchy. The boats of Viarreggio
carry from this port the goats’ dung of the Maremma, to manure the olive trees
of the Apuan coast.”

“From the peculiar circumstances in which our Maremmas are placed, they
are debarred from the benefit of a like restitution of the conditions of fertility.
Cultivation slowly improves, and the amount of produce reaped increases
every year; but the scanty and migratory population of a soil, deserted on
account of the miasmatic exhalations, cannot yield an amount of fertilising
matter in proportion to the quantity carried off from the land. The gradual
introduction of the system of the rotation of crops might slowly lead to the
same impoverishment of the soil which has resulted in other places from the
‘high system of farming.’ The apprehension lest this should in reality be the
result of it, has by no means escaped the attention of the proprietors and
cultivators of the soil in the Grand Duchy, who are so earnestly endeavouring
to make agriculture flourish in these parts. The barrenness and desolation
which has so long been the fate of the Maremma may, perhaps, be partly
attributable to the spoliation system of farming pursued by the ancient Romans
and Etruscans.”

“ Agriculture in Tuscany, then, is based upon the principle of restoring to
the soil those elements which science points out to be the most efficacious for
the growth of plants; and in this respect it is far ahead of the system pursued
in other countries,” &c.—(Set nuove lettere chimiche sul? agricultura di Giusto
Liebig, compendiate et annotate de Gustavo Dalgas, Dr. Philosoph. Firenze, Felice
Paggi, 1858, p. 93.)

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APPENDIX.

Lv, pee tee VL.

In the cultivation of grass for a season merely, or in the planting of
a particular kind of grass or of several sorts combined, the nature of
such grass or grasses is essentially a matter for consideration, but not
sc in the case of the sward. Just as the beech tree when standing
alone covers a broad space, and nearly sweeps the earth with its richly-
leaved boughs, while a number of the same trees, standing closely
together, tower upwards like columns, and merely clothe themselves
with branches and leaves at the very summit, so in the sward of the
natural meadow, plant closely clings to plant, altering its very struc-
ture in yielding to the law of necessity.

Those kinds of grasses which do this in a less degree, such as
meadow soft-grass (Holeus lanatus, L.), are on this account less suited
for meadow plants, whilst others, though coarse-tufted, such as cocks’
foot-grass (Dactylis glomerata, L.), and even turfy hair-grass (Aira
caespitosa, L.), form large separate tufts only with an inferior sward.

_ In the spring of 1857, I examined a patch of quite new grown turf,

which was exceedingly fine and close, taken from the ground facing a
ditch used for the draining of a large meadow; I found on an area of
11°85 square in. Hess., 265 grasses. On an older piece of turf taken
from the irrigated meadow having an area of 14:4 square in., I found
' 210 grasses and 12 other plants; and on another patch of an area of
13-2 square in., 150 grasses and 25 other plants.

222 APPENDIX.

These high figures sufficed to confirm me in my original supposition,
that only a small portion of the store of plants is completely developed
in one year, and that a change of plants takes place according to the
altered influences of the atmosphere and the soil; a fact which, ac-
cording to Thaer, has been already noticed by others, and, as it ap-
pears, was also observed by Schwerz.

It is well known that many plants, when a condition indispensable
to their perfect development ceases to exist, as for instance, where the
over-hanging shade of growing timber, or a too great clearance, pre-
vents their growth, will for years retain existence by the extension of
their roots, remaining as it were at a lower stage of growth, till there
is a return of more favourable circumstances for their development.

Thus we find that cleared ground will frequently become imme-
diately covered with plants, many of which, being perennials, such
as the raspberry, could not have sprung from seed. I have proved
that this state of things is very general and is not confined to cases
alone where the impediments to the growth of the plants are so con-
siderable, but that it applies also more especially to grasses, and is of
the highest importance in the cultivation of meadows.

Every one knows that ash draws forth clover plants (which, like the
grasses, do not flower the first year); and likewise that after manuring,
other kinds of grasses make their appearance on the meadow. I ob-
served on a plot manured with so-called acid-phosphate of lime, the
almost exclusive growth of a single kind of grass, French rye-grass
(Arrhenaterum avenaceum), which came up in thickly serried blades,
whilst on the unmanured ground but a few stalks presented them-
selves.

I have examined the stock of plants on meadows at the time of the
development of the culms. I had pieces of turf carefully cut out,
measured, and the soil washed away, which left a dense mat of closely
interwoven roots. There were found on one square foot, Hess. in. :

1. Irrigated meadow near Zerby: dry patch. Predominant:—Bromus
mollis, L., et Arrhenaterum avenaceum P.B. Size of sod, 22 square inches;
containing 472 plants; in stalk, 36,

APPENDIX. 223

2. Irrigated meadow, same place: wet patch. Predominant :—Glyceria
Jluitans, Size of sod, 20 square inches; containing 1230 plants; in stalk, 20.
3. Dry unirrigated meadow, near Fehlheim: manured with compost. Pre-
dominant :—Agrostis alba et vulgaris. Size of sod, 56 square inches; con-

taining 668 plants, of which there were 601 grasses and 67 other plants; in
stalk, 66.

The other plants consisted of Lysimachia nummularia, Bellis peren-
nis, L., Veronica chamedris, Ranunculus, Rumex.

4. Irngated meadow, near Fehlheim, somewhat mossy. Predominant :—
Poa trivialis, Festuca pratensis, Avena fiavescens, Festuca rubra, Agrostis vul-
garis. Size of sod, 55°25 square inches; containing 730 plants, of which
there were 584 grasses, 182 other plants; in stalk, 125.

The other plants consisted of Plantago, Daucus, Veronica, Rumen,
Ranunculus, Chrysanthemum, Trifolium repens, Lathyrus.

5. Meadow near Balsbach, in the Hessian Odenwald (counted by Peter
Kreuz, of that place). Predominant:—Agrostis stolonifera and Anthoxanthum
odoratum. Size of sod, 1 square foot; containing 1176 plants, of which there
were 1070 grasses, 56 clover, and 80 other plants; in stalk, 38.

6. Meadow near Balsbach, in the Hessian Odenwald (counted by Peter
Kreuz, of that place). Predominant:—Lolium perenne, Festuca pratensis,
Dactylis glomerata. Size of sod, 1 square foot; containing 790 plants, of
which there were 710 grasses, 80 other plants (before the second cutting,
without stalks).

7. Meadow near Balsbach, in the Hessian Odenwald (counted by Peter
Kreuz, of that place). Predominant :—Festuca rubra, Agrostis stolonifera,
Anthozanthum odoratum, Cynosurus cristatus. Size of sod, 1 square foot;
containing 920 plants, of which there were 800 grasses, 120 other plants; in
stalk, 14.

In numbers 5, 6, and 7, an entire square foot of sod was examined,
which must have been a most arduous and laborious undertaking.
The examiner (Mr. Peter Kreuz) says: ‘ We have carefully separated
the single plants, and to guard against mistakes, collected them in little
heaps of 10, and afterwards in heaps of 100 plants, by putting 10 of
the small heaps together.”

224 APPENDIX.

8. Unirrigated meadow in the parsonage garden of Hohenstein: not irri-
gated, mossy, with tolerably dry soil (counted by the Rev. Mr Snell, of that
place). Predominant :—Alopecurus, Ductylis, Arrhenaterum avenaceum. Size
of sod, 1 square foot, Nassau measure; containing 1040 plants, of which
there were 832 grasses, 80 clover, 128 other plants; in stalk, 208.

The other plants consisted of Plantago, Leontodon, Veronica, Lysi-
machia nummularia,

9. Dry unmanured meadow, near Feblheim: weedy (counted by the author).
Size of sod, 60 square inches; containing 379 plants to the square foot
(Hessian), of which there were 276 grasses, 103 other plants; in stalk, 0.

The other plants were Plantago, Prunella vulgaris, Bellis, Ranuncu-
lus, Hieractum, Veronica, Carex.

Sinclair found on one English square foot, equal to about 14 square
foot, Hessian in:

Clover and
Plants. Grasses, other plants.
Very rich natural meadow,
at Endsleigh, . ° : — e es
Rich old meadow, at Croft- 1090 1032 58
church, ‘
Old meadow at Woburn, ‘ 910 880 30
Old meadow at Woburn, soil 634 510 194
moist, surface mossy,
Trrigated meadow, : - . 18s 1702 96

If we place the figures given by me by the side of those of Sinclair,
properly reduced, we find that they agree as closely as can well be ex-
pected :

Hanstein. Sinclair.
1230 . . ° . ° ° . 1200
1176 ee ae en a eu ale —

920 ° . . . . ° . _
790 ° “ . ° . . . 726
730 Se ee ee =
668 . . . : ° ° . 666
472 : ° . . ° ° . 606
379 . . . . . . : 423

APPENDIX. 225

This comportment of the grasses is of the highest importance;
it explains the fact of the permanent duration of natural meadows,
and the certainty of their yield; it is this property that causes “ the
sward, which in the temperate zone neither heat nor cold can destroy,
to be clothed with perpetual verdure.”

The large number of plants which are in a low stage of develop-
ment, await, as if in a slumbering state, the coming of the time for
their perfect development; the more important plant is in such case
replaced by the plant of lesser pretension, until the conditions of per-
fect growth have again returned for the former.—H. Hanstein—Jour-
nal for Agriculture, [X. year, p. 270.

ADDENDA.

SHOULD THE FARMER BE EDUCATED?

ALTHOUGH it has been said that every farmer should not
try to be a geologist, meteorologist, chemist, etc., or study
medicine to be his own doctor, or law to make it unneces-
sary to employ a lawyer, or theology with the sole view of
doing his own preaching, still there is little doubt that all
general information, and the more exact the better, has a
great tendency, if well applied, to be useful to the farmer’s
best interests. Every cultivator desires to gather from the
soil, at small expense, large crops, with as little injury as
possible to the source of production. He cannot do this
without being familiar with general principles in the
various departments of his profession, and understanding
most thoroughly the art of agriculture. The man who
grows crops well must understand the nature of soils,
which certainly includes more research than would enable
him to arrive at the sage conclusion that one is sandy and
another clayey, etc. Then what should be the extent of
the farmer’s education? Who will answer the question?
One person is found fault with for being “ too scientific ;”
another, for not being enough so. Now, suppose all

228 ADDENDA.

should practise with science, cast away prejudice, and seek
to apply knowledge for its own dear sake, we might hope
for rapid progress in mental acquisition, national wealth,
and prosperity. If the farmer was not placed in such
close relation with almost every department of science—in
a word, with Nature’s endlessly beautiful and diversified
works—it would not be difficult to define what should be
the extent of his education. Let us apply truths as fast as
we discover them, and not find fault with the man of
science because he cannot supplant the Divine Architect.
It would be impossible for any agriculturist, during his
whole life, to study any one department bearing on his
calling to its fullest extent; and, therefore, who will ven-
ture to advise when he shall cease to explore and grieve
over the exhaustion of the realms of knowledge ?

1 SCIENCE AND COMMON SENSE.—P. 215.

Liebig truly says, “‘ Whatever practical agriculturists and
agricultural societies may do, whatever they may resolve
at their annual meetings, every penny spent will be thrown
away, and every year of experimenting will be in vain, so
long as these practical men will not submit to the teachings
of true experience, to the rules of logic or of common
sense; from the instant they shall so submit, science will be
theirs.”

How very different is the meaning of the expression
“‘common sense”’ when unfolded in the light of science as

ADDENDA. 229

compared with its ordinary acceptation. The words, as in
every-day use, are of little value, but how telling is their
effect when under the control of science, as used by Baron
Von Liebig. Some agricultural writers speak of ‘‘ common
sense unaided by science ;’ which seems to be a desire to cater
to the prejudices of an uneducated class of farmers. This
is beneath the dignity of a man, who should be guided by
truth alone. The expression convmon sense, as some people
use it, is exceedingly indefinite; for every person, from
the fool to the philosopher, has a common sense standard
of his own, differing from that of every other man; and
as no two minds are exactly alike, the varieties of common
sense are in proportion to the number of persons who ad-
mit such faulty expressions. Science has to do with the
observation and classification of the truths or laws of
nature. Common sense, as in every-day use long ago,
said the world was flat; science has proved it to be round.
She has resolved the once mysterious soil into the constitu-
ents or elements of plants, and told us of their qualities
and quantities. Common sense, as used by the crowd,
never said a word on the subject. Why should any one
say, as we find in some of the books, that “the roots of
plants themselves go out in quest of that food,” which com-
mon sense, unaided by science, tells us is “ by them communi-
cated to the plant?” To follow this style of argument
would be very uncommon sense. Agricultural writers
should not draw lines of distinction between the practical
intelligent farmer and scientific man. Science and practice
‘should come together; for in exact proportion to the union
between them will agriculture prosper. Why repudiate

2

230 ADDENDA.

science, and in the same breath say, “ If you wish to make
a youth a shoemaker, you must first send him to school in
order that his mind may be expanded and prepared to re-
ceive the seeds of practical instruction.” If the farmer is
to depend so much on “common sense,” and so little on
science, why does not the shoemaker, feeling that there is
nothing like leather, graduate with the wax-end in his
hand? which would be carrying out the maxim, “ Ne sutor
ultra crepidam.” Even tinkers claim that their collabora-
teurs should be men of common sense, but it is their busi-
ness to bottom kettles. A tinker need not trouble his mind
with the science of mining or the manufacture of the useful
metal which he hammers. The farmer who is averse to
scientific education, is but an agricultural tinker. Let the
cultivator of the soil arouse to the dignity of his calling.

Let it not be forgotten that science has made the rough
places smooth, and interlaced the face of Christendom with
railroads, over which the commerce of nations is sent to
and fro for the use of busy man. She has prepared the
way for, and sent the steam-engine through, the trackless
forest, disturbing the haunts of the red man and wild beast
with the sound of civilization, and, like Prometheus,
brought the fire from heaven to be the errand-boy of the
human race.

ADDENDA. 2a%

AGRICULTURAL MACHINES.

If necessity be the mother of invention, it will not be
denied that she possesses to some extent parental protection
over discovery. Invention and Discovery are members of
one family. In an agricultural point of view, necessity, in
this country, and indeed many others, has not caused the
gathering of knowledge for general application to the cul-
ture of the soil. New land is so easily got and so produc-
tive, except in a few places, that the necessity for modes of
culture other than those of the most common kind has not
been generally felt by landed proprietors. Let us think
of the growing want for soil on which to operate, by the
rapidly increasing home population, immigrants, and the
general introduction of labor-saving machinery. Necessity
has been, in this case, of great value to the nation in
developing its resources. The demand for labor-saving
machinery has called into action the intellect of the land,
which has invented and constructed for agricultural pur-
poses, reaping, mowing, and threshing machines, etc., all
suited for well cultivated soil, free from stumps, and equally
so to all other parts of the country, as fast as they become
so. The mowing machine lays a basis for more animal
food, for by it the material necessary for its production may
be gathered more easily. The fact that the agricultural
machinery of to-day—should there be no more inventions
—applies to soil all over the globe, may assist us in form-
ing a correct estimate of the future vastness of agricultural
operations.

252 ADDENDA.

At a great national exhibition, as for instance, like that
of the Fair of our American Institute, it is exceedingly in-
teresting to examine the labor-saving contrivances that
come from the mind, and to see visitors looking at the life-
like things, whose muscles of iron and steel perform so
important a part in the development of national wealth and
prosperity. Here may be scen the labors of the brain-
wearied inventor, of whom it has well been said :

“In the great scale of being which with God began,
there is no created intelligence which approaches him in
dignity. Next to the eternal Architect, at whose bidding
the vast machine of the universe came into being—whose
cunning hand moulded the wondrous mechanism of our
frames—he stands; creating out of the airy fabric of the
brain the magic forms which never die. Look back upon
the track of time, and what survives its wreck? Here-and
there upon the strand a solitary monument of literature,
of marvellous beauty—out of the millions of books which
have delighted their millions of men—survives to tell us
that the rest have perished; but every creation of the
inventor, from the first dawn of time to the present hour,
exists among us. As time rolls on it but widens the circle
and adds glory to the memory of those whose works sur-
vive them. ‘The names of millions have perished, but the
thoughts they thought will never die. Their blessings,
like the air and light, are now our daily life; but when we
reflect, we know there was a time when they did not exist,
and that the art of the engineer produced them all. Civi-
lized men have reared their monuments and worship at
their shrine. The splendid temple whose lofty arches

ADDENDA. 233

sprang into the skies, above the trees of the forest, and the
palaces of kings erected by a great nation and devoted to
them, is the world’s tribute to genius—the acknowledg-
ment of the mastery of the mind. As I stood within its
crystal walls, and gazed into its gorgeous dome, the
shadows of the mighty dead in solemn pomp passed by.
Archimedes, and Bacon, and Watt, and Fulton, Gutten-
berg, Galvani, Franklin, and Torricelli, and a host of other
immortal ones; and in shadowy outlines their mighty
works—the printing-press, the steam engine, the electric
wire, the foaming steamer, the unerring compass, the
roaring cannon. ‘The powers of the earth attend their foot-
steps—the lightnings of heaven obey their commands.
My soul drank in the inspiration of the fairy scene, and I
felt the dignity of his calling.”

Stop the machinery of the world for a day, and a blank
would be left in its history that would throw a gloom over
coming ages, Hven the plough and less respected plough-
boy should they forget their labors, fields of golden grain
would be things of the past. The labor saved by machinery
is applied to new purposes either mental or manual; and
the consequence is new development. The inventor of a
machine to do the work of many men and oxen is a useful
laborer,

234 ADDENDA.

7 MORE BREAD AND MEAT.—P. 1.

“The most urgent problem which the present day has
to solve,” says Liebig, “is the discovery of the means
of producing more bread and meat on a given surface, to
supply the wants of a continually increasing population.
The most important social questions are bound up in this
problem, which science is expected to solve.” The problem
spoken of by the great Liebig has a world-wide significance.
Let us look at some of its facts in their relation to our
own country with a view to showing the necessity for a
rational system of agriculture. The production of more
bread and meat is of daily increasing importance. We
want more in time of war and peace to sell to other people.
The increase of animal food is not keeping pace with the
increase of population. We have no figures of more recent
date than those given below, which, if not exact, come near
enough to the truth for general purposes. There is every
reason to suppose that the next census would show more
strongly the necessity for growing more meat. The follow-
ing table gives the number and increase of cattle in the United
States.

1840. 1850.
Horses and mules, . . 4,385,399 4,896,050
Neat cattle, , ; . 14,971,586 18,378,907
Swine, Ss ie 6, a ge Sa 30,854,213
Sheep, : : : . 19,111,374 21,723,290

The increase of population has been 85 per cent., while that
of cattle has been only 20 per cent.

ADDENDA. 235

In New England, New York, New Jersey, Delaware,
Maryland, and Virginia, the three principal meat-producing
animals, cattle, sheep, and swine, have been rapidly de-
creasing, as is shown by the following tables:

DOMESTIC ANIMALS IN THE OLD STATES.

1840. 1850. Decrease.
Horses and Mules, 1,612,883 1,529,189 83,694
Neat Cattle, . 6,172,569 6,033,841 138,728

Swine, . . 6,897,396 4,909,334 1,988,062
Sheep, . . 11,872,622 5,450,678 6,421,950

The population has been increasing in the Old States,
while the meat-producing animals have been decreasing.

It is now quite natural to look to some of the New States
for a supply. The following table will apply to the States
of Indiana, Ohio, Kentucky, Ilinois, Tennessee, and Mis-
souri :—

DOMESTIC ANIMALS IN THE NEW STATES.

1840. 1850. Increase.
Horses and Mules, 1,804,092 2,116,160 312,068
Neat Cattle, ~ 4,307,952 5,280,433 972,48}

Swine, . . 11,726,209 13,848,041 2,116,832
Sheep, . « 5,197,906 8,485,658 3,237,752

The increase of animals in these States for the ten years
ending 1850, is shown in the above table.
Our exports of breadstuffs and animal products were as
follow :—

236 ADDENDA.

1836—’40 inclusive, . . . . . $63,050,000
1842—46 it goes) od? wetaige \ Spe Fae
184¥e751 ~ lies [ais Gwe...» Mi@des 3G ie
1852—56 sient odd vol nwa Bas ee

From the foregoing it will be seen that our exports
during the periods named were gradually increasing, nor
is there any reason to suppose that the markets abroad are
falling off in their demand. These, of course, have their
influence on the money value of bread and meat. HEvery
pound of salted meat sent to other countries will affect the
price of animals in the most distant parts of the United .
States. This puts money in the pockets of producers, while
it increases the cost to less productive consumers who live
in the towns and cities. By looking at the first table, which
refers to the number and increase of cattle in the whole of
the United States, it will be seen that the increase has been
only about twenty per cent., whereas the increase in the
population has been thirty-five per cent. These are strange
facts to be true of the cattle raised on the soil of the United
States. And we are beginning to feel their result, for we
have had to pay more and more for meat—the price has
been gradually increasing for a long time.

Many farmers near large towns and cities cannot afford
to make butter and cheese from their milk,.on account of
the demand for it, and the facility of getting it to market
by railroads. This milk business is destructive to cattle ;
the calves as well as the milk are sent to market; and
these facts, of course, have their influence on supply and
demand.

ADDENDA. 237

It is impossible that the prices of meat should long
continue high in any town or city of importance ; for, if
the supply is abundant, the prices soon become equalized
all over the country, less the cost of transportation, the
means of getting it to market are so easy. The increase
in prices has hardly caused us to eat less meat; and as the
quality is improving with our appreciation, we do not break
up habits already formed—those of a meat-eating people.

These facts and figures do not show that the cost of
meat is owing to an unusually short supply of animals for
any one or two seasons, short crops, increase of foreign
demand (although this has had its influence), fluctuations
of trade, or to causes of much importance besides the
disproportion between the number of animals and our
rapidly-increasing population—that is to say, the results
have been subject to the invariable law of demand and
supply. The principle in this question is easily under-
stood. Ifa family of six persons have a given quantity
of meat which is equally divided, each person will have
twice as much for his share as would the individuals of a
family of twelve persons from the same quantity. The
same facts are true of a nation, which is nothing more
than a big family. Although animals are increasing in
the great North-West, there is a want on the part of the
increasing population of all the States, not being supplied
at the prices of by-gone days; nor is there any likelihood
of an immediate remedy. That meat will cost less under
this state of things, for a long time to come, is impossible.
We take it for granted that this increase in price for many
years past, as figures show to be true, puts this subject

238 ADDENDA.

entirely beyond speculation, excepting, perhaps, the sud-
den rise and fall of ordinary transactions of commercial
life, the details of which cannot be reasoned upon; but
they are hardly necessary to throw light on the future
operations of the meat-grower and cattle-breeder, in mak-
ing their calculations, with a view of finding a remunera-
tive market. .It is for these reasons, in part at least, that
we ought to regard what Liebig has to say on soil culture,
and be on the look-out for the best machines in the shape
of animals, as well as for all facts connected with breed-
ing, feeding, and caring generally, with the view to pro-
duce the largest possible amount of meat, of the best qua-
lity, at the smallest expense. It becomes a self-evident
fact that we must pay more for meat, use less of it, or
increase the supplies. This is at least encouraging to in-
telligent farmers. More attention must be paid to produc-
tion. This may be done in part, not only by increasing
the proportion of the industrious over the idle consumers,
but by exciting the best efforts of those engaged in agri-
culture in favor of the most rational system of practice.

It is pleasing to see every little while, statements in Eng-
lish journals relative to the purchase of choice animals for
the United States. The gentlemen who make the selec-
tions are invariably spoken of by the British press as spar-
ing neither expense nor trouble to obtain the choicest ani-
mals of the respective breeds considered worthy of special
attention.

But let the day soon come when the rich prairies will
grow cultivated grasses to support the best kinds of stock,
and to be no more consumed by fire.

ADDENDA. 239

The finer grasses should take the place of inferior ones,
and green crops should be more grown. The culture and
fertilization necessary for them are sure to prepare the way
for other crops.

The improvement in the quality of animal food in Great
Britain and Ireland, since the general cultivation of turnips
and other roots, is too well known to be spoken of more
fully. The same facts will be true with us wherever the
root crops receive proper attention. Before their introduc-
tion into England the fattening of animals to perfection in
that country was unknown. A slight increase in our ani-
mals and crops would amount to more than the total
expenses of the general government. In these days of steam
cars, steam ships, electric telegraphs, arctic expeditions, and
voyages round the world, too little attention is paid to the
grand source of human subsistence for a thousand million
of men, and it is a matter of some importance to every human
being to know that he will get his daily bread. It is the
first petition in the prayer which our Master left us as an
example. ‘Give us this day our daily bread” means much
in the domestic economy of a nation—how much more so
among nations when ships freighted with bread are passing
every ocean across the track of ships of war, one on its mis-
sion of peace and plenty—the other on its mission of war-
fare and death. At such a moment this question of more
bread and more meat from the same number of acres, with-
out exhaustion, and with better directed labor, is a question
of life, of power, and prosperity to our continent.

“The increase of population on the Eastern Continent
(says Mr. Jay in his Statistical View of American Agricul-

240 ADDENDA.

ture), beyond the capacity of production, is investing the
question of food in this age with a significance that never
belonged to it before, and the growing demands for bread
that come to us from Western Europe, give a world-wide
interest to the statistics of American agriculture, far beyond
that which they could derive ens from the wants of our
own countrymen,

‘“‘Consumption has there birertihate production, and
henceforth in England, France, Belgium, Holland, and a
great part of Germany, the food question will be the question
that must take precedence of all others, as the regulator of
commerce, and entitled to the first attention and the wisest
treatment on the part of Government.”

John Stuart Mill, the well known political economist,
says: “Suppose, then, that the population of Great Britain
goes on increasing at its present rate, and demands every
year a supply of imported food considerably beyond that
of the year preceding. This annual increase in the food
demanded from the exporting countries, can only be ob-
tained either by great improvements in their agriculture,
or by the application of a great capital to the growth of
food. ‘The former is likely to be a very slow process from
the rudeness and ignorance of the agricultural classes in
the food-exporting countries of Europe, while the British
colonies and the United States are already in possession of
most of the improvements yet made, so far as suitable to
their circumstances. There remains as a resource the ex-
tension of cultivation, and on this it is to be remarked that
the capital by which any such extension can take place is
mostly still to be created. In America it is rapid, but not

ADDENDA. 241

more rapid than the population. The principal fund at
present available for supplying the country with a yearly im-
portation of food is that portion of the annual savings of
America which has hitherto been applied to increasing the
manufacturing establishments of the United States, and which
may now possibly be diverted from that purpose to growing
food for our market. This limited source of supply, unless
great improvements take place in agriculture, cannot be
expected to keep pace with the growing demands of so
rapidly increasing a population as that of Great Britain—
and uf our population and capital continue to increase with
their present rapidity, the only mode in which food can con-
tinue to be supplied cheaply to the one ts by patel the other
abroad to produce tt.”

“One fact,” says the Mark Lane Express, “is clear, that
it is to Western America that we must in future look for
the largest amount of cereal produce.”

All these facts show the necessity for the vikiieiatish of
more bread and meat. We shall be compelled to look into
this subject with great care, and consider well the prepara-
tion, fertilization, and cultivation of the soil, also the best
- varieties of seed, their preparation, time of sowing, changing
of seed, quantity to be sown per acre, the habits of insects
and modes of preventing them from injuring crops, etc.; but
above all when elements of fertility are taken from the soil
to be sure to put them back again.

Our field crops, such as wheat, rye, barley, oats, Indian
corn, potatoes, the hay crop, etc., and stock are a necessity,
and there is no thanks for us to grow them as well as we know

how, for without them we should starve. But the vegetable
11

242 ADDENDA.

garden is more of a luxury, though it will soon be a neces-
sity. A farmer once knowing the value of good vegetables
could not think of living without them. Why should not
farmers generally, as well as citizens, eat cauliflowers,
cabbages, pease, beans, lettuce, spinach, etc.? But through-
out the interior of this vast country, how few give attention
to these commonplace but useful products of our gardens.

Many citizens pay extravagant prices for fruits, grown
here, and imported from foreign countries. Some of the
choice pears grown by a few persons in this country are
sold now and then at the enormous price of a couple of
shillings apiece. What harm would it be for farmers to
grow the finest pears, apples, peaches, plums, apricots,
nectarines, strawberries, and to eat them too, and when
they have too much for themselves give the rest to their
animals? And while we supply our bodily wants with the
necessaries of life let us not forget the charms of a flower-
garden, and to render our homes as comfortable as intel-
ligence and industry can make them.

4EXHAUSTION OF THE SOIL.*—P. 144.

Our pilgrim fathers, a couple of centuries ago, began to
till a somewhat stubborn but productive soil. They and
their children took all they could get, but put little back
again into the soil. This cannot be denied, while with all
honor we must regard them as the pioneers of American

* See pages 94, 108, 144, and 152.

ADDENDA. 243

agriculture. In the early history of this country our
fathers found an immense expanse, and their urgent neces-
sities calling for immediate action, they selected the most
prolific spots and began to grow crops. Here were the
washings of the highlands gathered, and localities like the
Miami Valley, the receptacles of vegetable decaying
matter for centuries, were interspersed through the whole
Atlantic slope. As men began to till the soil, and as fast
as they exhausted one locality of such elements of God’s
bounty as were in a condition, from their solubility, to act
as food for plants, they moved to new places rather than to
properly work or fertilize old ones. They were not the
servitors of their grandchildren, but with a vast country
' before them they chose to skim it, and as they drove the
Red Men westward, they found new fields for planting,
and they “skimmed” the land. Here the great mistake was
made, that of overrunning the soil to reap a few good
crops that ended in impoverishing it, and this bad
example has followed to the present day. Thus the
Atlantic slope became a depleted expanse, and unprofitable
with the modes of culture in practice.

‘(A writer in the ‘Year Book of Agriculture for 1855,’
on the ‘Alarming Deterioration of the Soil,’ referred to
various statistics of great significance in connexion with
this subject. Some of them regarded Massachusetts, where
the hay crop declined twelve per cent. from 1840 to 1850,
notwithstanding the addition of 90,000 acres to its mowing
lands, and the grain crop absolutely depreciated 6,000 bush-
els, although the tillage lands had been increased by the
addition of 60,000 acres.

244 ADDENDA.

“In Indiana the river bottoms, which used to produce
an average crop of 60 bushels of corn to the acre, now pro-
duce but 40. In Wisconsin, which is younger still, it is
estimated that only one-half the bushels of wheat are now
raised to the acre that were raised twelve years ago; and
the writer declares as the conclusion of the whole matter
that the soils of New England, after all the admonitions we
have received, are annually growing poorer, and that even
the virgin lands of the Great West are rapidly becoming
exhausted of their fertility.” *

The reader will find very interesting notes on the exhaus-
tion of American soil on pages 179, 180, 181, 220, and 221,
of this work.

We choose rather to give the researches of others, as
being most likely to convince the reader than the gleanings
of one mind. In examining the foregoing facts in relation
to short crops in some of the old states it will be well to
consider that the ravages of insects doubtless deterred many
from devoting the same area to the cultivation of wheat, but
this fact could hardly be true of potatoes and some other
crops; stillit would be well to bear in mind the probable area
devoted to the crops referred to. There is no doubt that
in the main the bad principle of EXHAUSTION is too true.
Liebig, in his “ Familiar Letters on Chemistry,” says: “ Is it
possible, after so many decisive investigations into the ori-
gin of the elements of animals and vegetables, the use of the
alkalies, of lime, and the phosphates, any doubt can exist as
to the principles upon which a rational agriculture depends?

* Jay’s Statistical View of American Agriculture.

ADDENDA. 245

Can the art of agriculture be based upon anything but the
restitution of a disturbed equilibrium? Can it be imagined
that any country, however rich and fertile, with a flourish-
ing commerce, which for centuries exports its produce in
the shape of grain and cattle, will maintain its fertility, if
the same commerce does not restore, in some form of
manure, those elements which have been removed from the
soil, and which cannot be replaced by the atmosphere?
Must not the same fate await every such country which has
actually befallen the once prolific soil of Virginia, now in
many parts no longer able to grow its staple productions
—wheat and tobacco ?”

Again he says, in the present work (p. 152), “ Let it be
remembered that in Virginia there are vast tracts of land
which at one time gave full crops of tobacco, Indian corn,
and wheat, now lying waste. In 1850 the tobacco crop
was eighteen million pounds less than in 1840. In 1850
the average yield of wheat per acre was only seven bushels!
The American farmer despoils his field without the least
attempt at method in the process. When it ceases to yield
him sufficiently abundant crops, he simply quits it, and,
with his seeds and plants, betakes himself to a fresh field ;
for there is plenty of good land to be had in America; and
it would not be worth his while to work the same field to
absolute exhaustion.”

Thus it will be seen our agriculture is a system of con-
stant depletion—it should be one of enriching and multi-
plying resources, involving all the elements of the soil for
‘the production of its fruits.

Some few enlightened agriculturists of the Atlantic

246 ADDENDA.

border have restored worn out lands, and made them
produce so bountifully, that in proportion to the capital
and labor bestowed they make more money, acre per acre,
than most farmers do from the unexhausted virgin soils of
the West.

Our wants are rapidly increasing. Whole districts,
which thirty years ago gave an average of thirty bushels
of wheat per acre, do not give ten bushels now. Until we
stop eating bread this subject will not lose its interest.
Why should we not grow as large crops, and of as good a
quality as can be grown? Does any one think good wheat
can be grown on bad soil? Can the land give that which
it has not ? .

If soil be too poor to pay for labor, the more of it the
wheat grower tills without renovation, the poorer that
land and himself will grow.

The common opinion, that the soil of the West cannot
be exhausted, is a great mistake. See how the crops have
fallen off, as shown by the tables already given. Grain is
carried to the cities, and the substances that made it are far
away from their original source. The wheat crop of 1858
robbed the soil of more than thirty million pounds of pot-
ash, and sixty million pounds of phosphoric acid. But a
small proportion of these elements is sent back to the
soil. In Nature’s economy nothing is lost; but when man
displaces things he should put them back again in their
own places. A wise nation looks well to its agriculture,
the great source of wealth. England dug the fields of
Waterloo for human bones to enrich her soil. She sent
her ships to foreign nations to bring home fertilizers. In

ADDENDA. 247

our agriculture we are a wasteful and soil-exhausting
people. We are tenants of it but for life; others will come
after us.

These are a few of the reasons, based on the bad principle
of EXHAUSTION, why our crops in many districts are falling
off.

In some places land is so much exhausted that crops to
pay for the labor cannot be grown. Again, we find soils
that are very rich, but not in balance; others are all that
can be desired, but they are the fewest, excepting those
we take from the hunting grounds of the red man, which
are as new to us as the Garden of Eden was to our First
Parents.

MANURES.*

The much agitated subject of farm fertilizers continues
to be of intense interest to every agriculturist, whether
he be the mere laborer or the intelligent working farmer,
whose motto is, “ Practice with science.”

The investigations that are being made in the laboratory
of the chemist, the farm-yard, and in the field of nature,
operate to increase new interest in behalf of the superlative
importance not only of the ordinary facts that attract
attention, but also of the abstract truths that guide uner-
ringly to the goal of perfection.

The proper manipulation and fertilization of the soil
furnish a great basis for national wealth and prosperity.

* See pages 82, 108, 173, and 183.

248 ADDENDA.

It is only by means of manure that the equilibrium of
the soil is restored.

Like the farmers of England and other nations, we, too,
have our strenuous and prejudiced advocates of the nume-
rous modes of practice detailed by agricultural lecturers,
manufacturers of agricultural books, as well as the novel-
ties presented by the motley groups who constitute those
assemblages denominated Farmers’ Clubs. ‘There is every
shade of intelligence, from him who simply knows that a
cabbage grows, and that he eats it, to the man of sound
mind and sound body, who interrogates the silent opera-
tions of nature to reveal to him structures of animal and
vegetable life which are infinitely more beautiful and
grand than the most ponderous artistic and imposing edifice
that has ever been raised on the surface of our globe by the
hands of man.

Many men of as many minds, and a much larger number
of theories, herald forth detailed accounts of faulty experi-
ments, both orally and in printed periodicals; the latter
too often furnishing space which might remain unoccupied
unless the greasy leaves of cookery books were explored
to grace the columns of the agricultural press, thus giving
opportunity to laudation or abuse, either of which is far
easier than the discovery of new truths. Some of the
experimenters give good sense and the laws of nature as
wide a berth as possible; and their ill-directed labors furnish
results more remote from truth than those of the most
careless operator who tills the soil in the sweat of his brow.

What vast amounts of labor and capital have been
wasted in testing the value of fertilizers! Farmers often

ADDENDA. 249

repeat the same experiments a hundred times, without its
being known to one another that they do so; but few of
the results of their labor and capital are recorded. Experi-
ments in the field, to be of value, must be exact; if not,
the tendency is to confuse rather than instruct. The writer
once saw a neighboring farmer, when planting potatoes,
use as fertilizers, farm-yard manure, guano, bone-dust,
phosphate of lime, wood-ashes, plaster of Paris, salt, caustic
lime, oyster-shell lime, water-slaked lime, the salt and lime
mixture, and muck treated with salt and lime. Each was
used separately, and in different parts of a field, having the
same quality of soil throughout, and all done with the
view of ascertaining what kind of manure was best for the
potato! No attention was paid to the chemical or me-
chanical qualities of the soil, its requirements, or those of
the crop about to be grown. Men who thus blindly grope
in the dark are the first to advocate, dogmatically, some
extreme notion in relation to long or short manures, their
treatment and modes of application. . We freely admit that
among the more intelligent of our profession may be found
the advocates of long and short manures, the deep drainers,
and the shallow drainers, as well as those who are favorable
to the many intermediate shades of difference, without any
modes in particular, being supported by the unanimous
voice of agriculturists. The explorer should not be guided
by the dupes of any theory in particular, but rather seek
from every source that which seems most rational, and in
best obedience to the unerring laws of nature.

Chemical science has searched into the nature of the soil,

the plant, and the air, and has shown that the word sovl
it

250 ADDENDA.

means several substances rather than one, and that this is
also true of the word plant, and the word air. The soil
and the air are the sources whence the material necessary
for the building of the plant is obtained.

Let it be remembered that the plant is not a single or
simple substance, but is made up of several. If a piece of
wood is burned, ashes will be the result. During the burn-
ing some parts of the wood pass into the air. The house-
keeper is in the habit of leaching the ashes to.get lye for
making soft-soap ; a large per centage of this lye is potash,
which came from the ashes, which came from the plant,
which came from the soil on which the plant grew. This
substance, potash, is one of the several which compose the
ashes, such as lime, soda, and so forth. If, then, researches
have shown that the absence of particular substances in the
soil prevents some plants from growing successfully, and
that supplying them in a proper manner restores fertility,
we get at a simple and truthful explanation of a principle
which must govern the action of all fertilizers. The word
manure, like the word sozl, means more substances than
one; and different manures must vary in action as they
vary in composition, even if all other things are equal.
These principles have their home in nature; nor do we
lay any claim to their discovery. The honor of this is due
to greater minds. We are but the errand-boy giving the
message to our readers.

What is amanure? It is that substance, whether simple
or compound, solid or fluid, which yields to a plant food
essentially necessary to its structure and development.
According to this definition, water is a fertilizer, and such

ADDENDA. 251

constituents of the air and soil as go to support plant
life.

The farmer should consider what food is essentially
necessary to the plant about to be grown.

What food is essentially necessary to the plant about to
be grown?

From what source of advancement should the food be
supplied ?

What should be its mechanical and chemical condition
in the soil ?

These are a few of the important questions that relate to
vegetable growth.

Practice has fully satisfied experimenters that if any of
the elements of which plants are composed be absent from
the soil, they will not grow to perfection, and that the
most perfect result can only be obtained from soils in exact
balance. Qualitative and quantitative analyses of plants
and soils have cast much light on these important features
of the subject. The old notion that plants can create food
is now abandoned by every intelligent mind.

An animal fed on hay and oats will not furnish in its
excreta the precise constituents, in the same relative pro-
portions to each other, as they exist in the food.

All the most valuable, most needed, and ready-to-be easily
assimilated portions, such as are in an advanced condition,
go to increase the size or bulk of the animal, or to make
up for the wastage of the system. All that part of the food
known as starch and gluten, or a very large portion of it,
is not to be found in the excreta, unless the animal be
over fed. The elements of farm-yard manure are not in

258 ADDENDA.

as advanced a condition as many of the crops to which
they are applied, but many of them are on the very next
plane of existence in the scale of progression, and must,
therefore, be particularly suited for the production of the
same plants as those from which they arise, and for all
others of an analogous newness of creation.

This principle must be clearly understood, and admitted,
before the reader will be prepared to comprehend the ra-
tionale or method of treating manures. Every vine-grower
knows that the inorganic substances of the soil that go to
make the wood of this year will be rendered fit pabulum
for the fruit of next year, if made soluble by natural pro-
cesses. Thus, the vigneron cuts the trimmings of his
grape-vines, with an ordinary straw-cutter, and after hav-
ing buried them in damp soil during winter applies them
in the spring around the roots of the growin gvines, and
increases the amount of fruit by doing so.

Now, it must be evident, that when these cuttings are
applied to the root of the same vine from which they were
removed, no new inorganic matter is added to the soil,
but it is simply that the same inorganic substances are
replaced in the soil after having been progressed, by once
assuming the form of wood, and that, therefore, without
any increase of quantity, but only from superior condition,
that the increased amount of fruit occurs. If this principle
be correct, a hay crop undergoing decay beneath a soil
where hay is intended to be raised for its seed, the
quantity would be greater than from a less advanced
manure, and simply because the constituents of the hay
were ready for re-assimilation; and it is to this fact that

ADDENDA. 253

stable manure, in no small degree, owes much of its
value.

Liebig, on a strictly. chemical basis, truly says, that
“THE SOLID AND LIQUID EXCREMENTS OF AN ANIMAL
ARE OF THE HIGHEST VALUE AS MANURE FOR THOSE
PLANTS WHICH FURNISHED FOOD TO THE ANIMAL.”

For a full understanding of the value of farm-yard
manure, it will be necessary to consider its source and
composition, and causes for the changes it undergoes, as
compared with the integrants of the materials from which
it arises.

Plants receive support from the soil; they nourish
animals; but certain portions, not appropriated, are known
as liquid and solid excrements.

The analysis of any specimen of farm-yard manure
cannot be viewed as a universal standard of comparison.

The peculiarities of animals as mere machines, the
quantity and kinds of food consumed by them, their age,
amount of exercise, climate, season of the year, the bear-
ing of young, the giving of milk, and a variety of other
circumstances, have a great influence on the composition
of manures. ‘The drainage of some compost heaps is
exposed to rains, evaporation, or permitted to flow away
to creeks.

Others are carefully protected, but parts of them may
abound in straw. Occasionally, farmers permit their cattle to
roam and feed in the farm-yard, and they often waste as much
food as they consume. How difficult, then, is it to select a
sample for chemical examination, the analysis of which will
be an exact representation of farm-yard manures in general.

254 ADDENDA,

The loss of ammonia during the preparation of farm-
yard manures has been and is attracting much attention.

The pungency of the odor given off from fermenting
substances is no indication of the quantity of ammonia
liberated. Many agricultural writers give Dr. Voelcker
the credit of having made this discovery. The value of
the Doctor’s experiment consists chiefly in following out
the detail of a principle, the credit of which is entirely
due to Baron von Liebig. It is no new information to
the agricultural world to be told that decaying animal
substances, in addition to eliminating ammonia, also give
off “ sulphuretted and phosphuretted hydrogen, and a great
variety of gaseous matters,” to which the pungency of odor
referred to is due to a very considerable extent. But it is
quite novel that agricultural writers should deduce from
Dr. Voelcker’s researches that manures may be exposed on
the surface of a soil without loss, and especially because
his analyses show with great clearness the loss that must
necessarily arise from drainage by water, on account of the
great solubility of some of the compounds. In comment-
ing on the analysis of drainings from a dung-heap, he says:

“Tt will be seen that these drainings contain a good deal
of ammonia, which should not be allowed to run to waste.

“They also contain phosphate of lime. The fermenta-
tion of the dung-heap brings a portion of the phosphates
contained in manure into a soluble state, and enables them
to be washed out by any watery fluid that comes in contact
with them.

‘“‘Drainings of dung-heaps are rich in alkaline salts,
especially in the more valuable salts of potash,

ADDENDA. 255

“By allowing the washings of dung-heaps to run to
waste not only ammonia is lost, but also much soluble or-
ganic matter, salts of potash, and other inorganic sub-
stances, which enter into the composition of our crops,
and which are necessary to their growth.”

The Mark Lane Express, of London, republished an
article, by an American writer, containing the following
language :—

““<Those who imagine,’ says the editor of the Working
Farmer, ‘they find good results from spreading of the
manure on the surface, and leaving it for days, weeks, or
months, before it is ploughed under, mistake the action of
the litter or longer portions of the manure as a mulch for
the action of the manure on the soil.’ Weso far differ from
this and kindred opinions on the subject that we think
manuring on the surface, for ninety-nine farmers in a hun-
dred, the best general method of application.”

The author quoted, edifies his readers by saying, ‘‘ we
think manuring on the surface, for ninety-nine farmers in a
hundred, the best general method of application.” Nor
does he favor us with any other rationale than his sage
thought!

One very serious error has been caused by the recent
discussions on ‘‘ Farm-yard Fertilizers.” Impressions have
been made on the minds of many farmers that science at
last has discovered that the ordinary system of treating
farm-yard manure is correct, whereas the experiments of
Dr. Voelcker, which gave rise to the excitement both on
the other and this side of the Atlantic, do not go to prove
any such result. Many of the agricultural journals of

256 ADDENDA.

Kurope and America, whose editors desire to cater to pre-
judices, were highly pleased to have an opportunity of fur-
nishing such material as would delight a certain class of
readers, and be the cause of exciting the advocates of oppo-
site views to action.

There is no doubt that portions of manure spread on the
surface of a soil are washed into it. The quantity carried
into the soil by the soluble and mechanical action of water,
will be governed by its composition (whether clayey or
sandy) and its mechanical condition. It is also admitted
by the wisest advocates of the foregoing, that many and
large amounts of the elements essential as food for plants,
are carried to the lowlands in obedience to the same laws
that cause alluvial deposits. 2

In direct opposition to these well known truths, a writer
in the Edinburgh Journal of Agriculture furnishes the ex-
tract given below, which has been published in almost
every agricultural paper in the United States. Care has
been taken to say that the “striking experiments” were
made by a scientific man, and by certain explanatory quali-
fications to give more importance to the man than to the
subject.

If the experiments be striking, it is because they appear
very unceremoniously to strike Dame Truth in the face.
The writer in the Edinburgh journal says:

“There being a difference of opinion among scientific
men regarding the advantage of spreading dung upon the
surface, and leaving it exposed for some time before cover-
ing it in, Professor Legnitz, of Eldena, had recourse to ex-
periment for the solving of the question. For this purpose

ADDENDA. 257

he selected two and a half roods, which he divided into four
equal parts. To No. 1 no manure was given, No. 2 re-
ceived about two tons of farm-yard dung, which was spread
immediately and covered in by means of the plough. No.3
was treated in the same manner, with this difference, that
the hoe was used instead of the plough.

“The same quantity of dung was carried to No. 4, and
allowed to remain spread for three weeks on the soil before
being covered in by the hoe. On the 10th of October the
four lots subjected to experiment, were sown with about
ninety-five pints of rye-seed each. The following are the
total results of the crop of each lot, grain and straw included:

No. 1 produced ‘ : ‘ 583 Ibs.
No. 2 produced : ; : Tree“
No. 3 produced : : : S1e*'*
No, 4 produced os ‘ 935 %»

The author of the above has well said, that one experi-
ment should not be considered conclusive, and we will
suggest that he might have added, especially because the
full conditions for a useful experiment were not present, and
such as were, not recorded in a manner to be of value.

In the first experiment no manure was used, nor does it
appear that the soil was ploughed, and as might be expected,
it gave the smallest crop.

In the second experiment, manure was used, and the soil
was ploughed in the act of covering it, and, as was reason-
able to expect, the crop was larger than in the first-named
instance.

In the third experiment an equal quantity of manure
was given to the same surface of soil, but instead of

258 ADDENDA.

ploughing it under, a hoe was used to cover it, which gave
the soil more mechanical disturbance than the plough; the
latter turns the soil over in masses, whereas the former acts
with greater intensity, and on small quantities of soil during
its vigorous action, thus abrading the surfaces of particles
more fully than could be accomplished by one ploughing,
for which reason there was a greater amount of plant food
liberated, and as might be anticipated, the crop was larger
than in the case of the second experiment.

In the fourth experiment, and to which the others are
merely introductory, the result is such as clearly indicates
unusual conditions, such as the manure, perhaps, being so
fermented before its use as to present a large proportion in a
soluble condition, its application followed in all probability
by heavy rains and dews, while the long undecomposed por-
tion remaining on the surface of the ground for three weeks,
acted as a mulch, and probably during such a state of the
atmosphere as to produce its greatest action as such, and
when evenly ploughed in, the same ploughing that turned
under the mulch, mixed the soil through which the fluid or
manurial portions had previously been well disseminated.
The chemical conditions of the soil may have been more
favorable than in either of the other three experiments.

No account is given of the condition of this soil as com-
pared with the others, for a second crop, nor of the kind
of weather occurring during the three weeks referred to.
If the experiments were made during a season of drought,
the effects would not have been such as are stated; or during
a season of excessive rain on soil not previously disturbed,
no such result would have been produced. It is quite com-

ADDENDA. 259

mon to see tall grass where an old plank or rail has covered
it for a time, which, acting as a mulch, causes the growth
of better grass than would have been produced by an ordi-
nary quantity of manure, but to no small extent evidently
at the expense adjacent of grass. The portion so mulched
receives and fixes a larger quantity of fertilizing gases from
the atmosphere. Weare not told whether the soil used for
the fourth experiment was or not on a lower level than
the surrounding soil on which the others were made, and
thus benefited by water flowing from No. 2 and No. 3, said
water carrying elements of their fertilizers and soil to No. 4.
Nor is it stated that the manure in each case was alike in
quality. Indeed, the account is altogether too inaccurate
to be reliable, and therefore should not have been published
without comment in the most important agricultural jour-
nals in England and America.

Let it not be forgotten that the fluid portions of manure
are highly valuable; the various salts they contain are in
a state of solution, and are capable of extreme division, in
addition to assisting by their presence all the sus generis
actions of a chemical character which take place im a soil ;
for just as yeast multiplies itself in a brewery by its action
on vegetable matter, so do the constituents in solution in
the urine of animals induce chemical changes which cause
the integrants in the soil to be rendered suitable pabulum
for plants.

From the foregoing it must be evident that the excre-
ments of all animals should be well cared; and their mani-
pulation should be such as not only to secure their con-
stituents for the use of plants, but to change the condition

2.60 ADDENDA.

of such of them as plants cannot avail themselves of, by the
usual treatment of the manure before it reaches the field.
In addition to the inorganic matter, are many proximates,
known as organic compounds, which plants may use, and in
a condition which renders them active in the further decom-
position of a soil for the use of plants. Among these are
the bile and chyle of the animal, and the different vegetable
proximates not appropriated ; and we are sorry to say that
most farmers, by the injudicious management of manures,
lose them by evaporation, washing, etc., and also much of
the more valuable and most soluble of the inorganic consti-
tuents. These occur in open farmyard practice, and in the
washes and streams that pass away, sometimes crossing
roads, on their way to creeks and rivers, while from the
exposed surface ammoniacal and other gases, hurtful to the
health of animals, pass into the atmosphere.

Some of the losses that arise from improper exposure
are as follows:

The most soluble elements, and consequently the most
readily available constituents to plants, are washed out by
rains. If the manures permeate the farm-yard, a larger
amount of surface is exposed to evaporation than if
gathered into a heap.

The amount of surface exposed to evaporation is a great
number of times increased if cattle are permitted to roam
promiscuously through the yard. Every step taken by an
animal exposes a new surface to the action of sun and air.
Every spear of hay or straw projecting from the surface of
manure, by capillary attraction, gives an increased amount
of surface for evaporation.

ADDENDA. 261

The proper composting of fertilizers is, to American far-
mers, of more importance than to the English cultivators of
the soil: because gases from any decomposing substance,
whether animal or vegetable, cannot so readily pass into an
atmosphere like that of England, Ireland, or Scotland, as
they will into that of America, owing to the sudden changes
of temperature of the latter.

Any vegetable matter that can be decomposed in a com-
post, should not be burned, It is not proper, therefore, to
subject witch or couch grass, clippings of hedges, or live
fences, leaves, or other similar materials, to the action of
fire. They ought rather to find their way to compost
heaps, and receive such treatment as will secure full de-
composition. Let everything of a manurial character find
its way to the compost. Remember the Scotch adage:
“A stone is the only mote in a muck heap.”

Such adages, now being published in so many of the
agricultural papers, that ‘“‘ No one should have a farm-yard
bigger than the body of his ox-cart,” are mere words with-
- out meaning. It would be well for the authors of such
sayings to give accompanying explanations. One-sided,
prejudiced views never lead to truth; writers should not,
Paganini-like, play on a single string.

LAND DRAINAGE.

There can be little doubt that thorough drainage is one
of the surest means of preparing the soil for the applica-

262 ADDENDA.

tion of the principles so ably set forth by Baron von
Liebig.

We have no space to devote to the history of this impor-
tant subject; there is, however, little doubt that improve-
ments in the art of drainage, extending over a long series
of years, show conclusively, the applicability of thorough
land drainage to a large proportion of our continent. Its
advantages are very numerous, a few of which may be
briefly stated. Its object is not merely, as many suppose,
to rid the land of stagnant water. The action of the air on
the soil, and the absorption of moisture from it by the
driest lands that are under-drained and deeply cultivated,
are advantages that are now well considered by the intelli-
gent practical farmer. Soils, especially such as are full of
stagnant water, treated in this way, are easily worked,
when the water is carried away by under drains; and this
is particularly true of them when sufficient time has
elapsed to permit those important influences of the air
which liberate pent up food, and thus improve its physical
condition, thereby lessening the labor necessary for their.
successful culture. Under-draining, even without the appli-
cation of manure, has been known to double the crop in
many soils. Let it not be forgotten, however, that in this
point of view, it aids the “rapid system of spoliation,”
unless the farmer restore to the soil the elements taken
away by crops. In under-drained soils, when the drains
are at full depth, the roots of plants can strike deeply in
search of food; thus they are invigorated and not likely to be
thrown out or “winter-killed” by frequent freezings and
thawings, or summer-killed by not haying a deep soil

ADDENDA. 263

in which to luxuriate and absorb the moisture which is
sure, in the hottest weather, to be deposited on the
cool particles. It is also well known that under-drained
soils are warmer than those full of cold stagnant water.
They are earlier in spring and not frozen till later in the
fall, thus giving the farmer a longer season in which to do
his work. What can be more uninviting than a cold, wet,
unproductive soil? ‘Can the rush grow without mire?
Can the flag grow without water?” After thorough drain-
age, the rush and the flag disappear, and instead of coarse
grasses, alders, skunk cabbages, mosses, and other rubbish,
fine plants may at once be grown.

Into low, wet places much of the fertility of the higher
lands is washed by the soluble and mechanical action of
water, which is made available by thorough drainage, and
a basis is thus laid for all possible improvements of the
soil.

Although the farmer who can buy new and rich soil at
avery low price, is not likely to under-drain it, because he
can buy more land at little cost, which, although studded
with stumps, that will yield him full crops of cereals; still
few will doubt that thorough drainage is applicable to
extensive tracts of land near large cities, used for agri-
cultural purposes. Indeed that the farmer must drain
all such lands that are wet, or do without crops, few will
doubt.

George W. P. Custis, Esq., at the meeting of the United
States Agricultural Society, in 1857, asked attention to
100,000 acres of rich land, on the banks of the lower Poto-
mac, now lying waste, but which if thoroughly drained,

264 ADDENDA.

might at once be rendered available for the production of
the finest crops. This is only one case among many
beyond number which must yet yield to the almost magic
influences of thorough drainage as the agricultural resources
of our country are developed. A wide field for opera-
tion offers itself in the fifty million acres of swamp land
granted by Congress to different states during the past ten
years, with the hope that their governments will reclaim
them. Many a farm, by the drainage of low places, would
add quite a number of acres which have received the wash
of the highlands for ages, capable of immediate cultiva-
tion and profit.

The drainage of the Central Park, under the direction of
George HK. Waring, Jr., Esq., is probably the most thorough
work, on a large scale, that has yet been done in this coun-
try. Enough of this is already done to see to some
extent its efficacy ; although the drains have not yet been
long enough made to act in the best manner, still the water,
clear as crystal, may be seen gushing from the almost
magical pipes. On the land appropriated for the park,
there were many offensive pools, half full of decaying
vegetable matter, whose value, as a manure, to other parts
of the grounds, would more than pay the cost of drainage.
As the park consists of a great variety of soil, among
which may be named both blue and yellow clay of the
most tenacious kind, there is a fine opportunity for seeing
the effect of tile drainage by farmers who may visit the
grounds.

The first thing to be done in the laying out of drains is
to understand the natural lay of the ground, selecting the

ADDENDA. 265

lowest part, having the best outlet, as the line for the main
drain. The lateral drains should connect with the main at
the same angle as the slope of the ground to the line of the
main. Where the slope is not sufficient to give a self-evi-
dent fall it will be necessary to have the ground levelled by
an engineer, as any inaccuracy in this respect would be
fatal to the efficient working of the drains. The engineer
proceeds by driving stakes, of two or two and a half feet in
length, in the ground at given intervals along one of the
intended sides of each drain, and they are lettered and
numbered for easy reference. Beside each of these stakes,
a shorter one is driven, the top of which should be a little
above the ground, so as to be easily seen. On the shorter
stakes the engineer’s rod is placed as occasion may require,
when observations are made to ascertain levels. After the
calculation of the grades, the depth of the intended excava-
tion, from the top of the shorter stake, is marked in feet
and tenths on the longer one.

It is well to sound the lines of the drains with a sound-
_ing-bar, to ascertain whether rocks, separate stones, boul-
ders, etc., will much interfere with the cutting of them; in
which case new lines would have to be found. The obser-
vance of this precaution will save a great deal of labor and
expense. A sounding-bar is a round iron rod about an
inch thick and five or six feet long, tapering towards the
point and enlarged at the head to about two inches in dia-
meter; having a cross-bar about eighteen inches long through
an eye in the head. Sounding-bars three-quarters of an
inch thick, and seven or eight feet long, are sometimes used;
but they have to be scoaamaey uae the ground by a swinging

2

266 ADDENDA.

motion of the hand. This is a very slow process, compared
with the speed with which the larger sounding-bar may be
driven into the ground by a sledge. Twenty soundings
may be made with the larger bar, while one is effected with
the smaller one.

The main drain and laterals being located, commence
digging at the outlet of the main, and so proceed to the
head of the drain—that is its most distant part from the
outlet. Care must be taken to give them a regular and
sufficient fall, which should not, if possible, be less than one
foot in 100. A uniform. grade on the bottom of the drain
is very desirable; and itis for this reason that levelling-rods
are used. A levelling-rod is shaped like the letter T andis
made of board about one inch thick, five or six inches wide,
with a piece of board of same width about eighteen inches
long nailed across the top, and square to, that is at right
angles with, the perpendicular. All the rods must be the
same length; otherwise a uniform grade cannot be obtained.
Levelling-rods are usually made six or seven feet long.

Having got the drain as nearly as possible to the required
depth, place the rods on the bottom of it in an upright posi-
tion about forty feet apart; then hold another rod, which
may be lighter, on the bottom of the drain, and if its grade
be correct, the top will lie in a line with the tops of the ~
other two. Great care must be taken not to go below the
proper grade, as in that case the bottom of the drain will
have to be filled, and cannot be made as compact as the
natural bed. Where it is necessary to have the land lev-
elled by an engineer, and the fall is only sufficient, the rods
must be placed very accurately at the depths—ealculated

ADDENDA. 267

from the “levels’—which are generally marked on stakes
at proper distances along the lines of the drains. Beside
each stake, so marked, is the grade stake, the top of which
is a fixed point from which to measure the depth of the
drain. In order to find the exact depths of points along
the bottom of the drain corresponding to the depths marked
on the stakes, a sliding measure is used having a plumb-
line attached. First ascertain the required depth from the
top of the grade stake to the bottom of the drain; then
apply the sliding measure, the arm set to the proper height.
If the bottom of the drain be soft, place a flat stone under
the end of the sliding measure, making due allowance for it
when removing the soil from the point where the levelling
rod is about to be set. The sliding arm of the measure
must rest on the top of the grade stake. When the proper
depth is thus ascertained, remove the measure and place
the levelling-rod upright on the stone, it being held in its
position by a board reaching across the drain having a slit
in its centre into which the levelling-rod is wedged.

The main drain dug and graded, then proceed with the
laterals, commencing with those nearest the head of the main
and proceeding on to those nearest the outlet. Commence
to lay the tiles first in the main drain, and continue a little
beyond the point where the highest lateral connects. Pro-
ceed in the same way with the rest of the laterals, laying
the tiles connecting with the main, and then place inverted
sods, if the soil be silty, and cover with soil to the depth of
a foot and a half, and use.a pounder to compact. Every
foot of soil put in afterwards should be pounded. These
precautions will prevent water in case of a rain storm from

268 ADDENDA.

rushing rapidly through, before the soil has become settled;
on the contrary it will pass gradually without carrying any
silt into the tiles. Continue to dig laterals and lay tiles in
the main and in them as fast as dug until the outlet of the
main is reached.

INDEX.

PAGE
ABSORBENT power of soils varies 28
Agricultural Colleges system of
instruction in,
defective. . 209
the cause of the

present conflict
about — princi-
_ ples : . 210

— instruction, how ac-
quired : aris

— prize questions . 16

= teachers, errors of . 161

Agriculture, based on expe-
rience F ee
— connection with
chemistry . .- €
— false teachersof . 11
— modern, deficient in
principles . » 18%
— present system of,
not rational . 20
— spoliation system of 144
— spoliation system

of, in America . 144
Agriculturist, the empirical, a
trader ; . 138

— the scientific du-
ties of ‘ . 140

Air, carbonic acid and ammonia
in 3 F F : . 69

America, exhaustion of soil
in ‘i « GA TT

Ammonia, action of, compared
with that of water 165
— amount of,inair . 69

PAGER
Ammonia, combination of, with
soils 2 170
— effect of salts of
attributed to the
nitrogen. 43
—_— effect of salts “of
on production of
straw and leaves 80

— exhaustive action
of salts of . LPT
= experiments with
salts of, at Bogen-
hausen : 44
—_ in a soil, not a sion
of its fertility » 69
= quantity of, in
soils 59, 169

— quantity of, no cri-
terion of —
tiveness . 59
— salts of; double ac-
tion of j in soils 52, 167
— solvent action of,
on earthy phos-

phates : . 48

— without mineral

matters, of no use
to plants. - 88

Ammoniacal manures, when
useful 98
Annuals, absorption ‘of food by al
Apatite . : 96
Appendix : : . 221
Arable soils, how formed rig
Ash constituents. : . EEG

270

PAGE

B.

Bavarta—experiments of agri-
culturai society of, with am-
monia aig Ne

Beet—minerals removed by . 182

Birkenfeld peasant, his opinion
of clover ; . 160

Block, Albrecht, opinions of! F44t

Bogenhausen experiments with

salts of ammonia, &. 44
— experiments with
nitrate of soda. 47

Bog-water, analysis of . 2286

Bone earth, comparison with
Chili-saltpetre . ; . 178

C.

CARBONIC acid, amount of inair 69
source of . 70
Cato, opinions of, on agriculture 190
Cattle, stock of, not necessary . 198
Cereals, amount of nitrogen in 74
Chemistry, connection of, with

agriculture . . 4
— elementary instruc-

tionsin lg . 206
_ reaction against . 5

Chili-saltpetre, effects of, . y OAT
solvent action of,
on earthy phos-
phates 2 48
comparison of, with
guano and farm-
yard manure. 162
exhaustive effects of 67

China, continned fertility of
land i in 5 . 204
Chinese, agriculture i a . 200

— mode of collecting
human excrements ib.
— mode of sowing wheat 202

— valuation of human
excrement. . 201

Clover, introduction of into

Germany : - 155
— and corn, relation of, to
each other . . 149

INDEX.

PAGE
Clover, and potatoes, phusphorie
acid and
potash re-
moved by 102
Columella, opinions of, on agri-

culture ; 189
Combustible matter of plants
derived from air . ‘ « 110
Common salt, effeets of . 43
— — experiments with,

at Bogenhausen. 44
solvent action of, on
earthy phosphates 48
Compensation, the law of — . 205
Corn, mineral matters of, lost
to the land ‘ . 150
— and flesh, mutual rela-
tion of the production
a ‘ ; . 199
Crops, rotation of . : . 142

D.

DEEP rooting plants, effects of 105
Disintegration of rocks . . 122
Distilleries, residues from 169, 180
Drainage water, ammoniain . 34
analysisof . 31

E.

Kartu, outer crust of, conden-
ses and retains the food of
plants . 40
Earthy phosphates rendered
soluble by salts of ammonia,
common salt, and Chili-salt-

petre . 48
Excrements ae man, ‘amount of
in large towns. : . L6G

Exhaustion of soils, law of . 94
real nature of 108
Experience of practical men as

a guide . . ‘ . 120

F.

Fatiow, effect of . . 98
False reasoning : - 127

False teachers .
Farm-yard manure. .
value of .
Fertility, duration of, propor-
tional to amount of
mineral matters in
soils 3
how maintained.
not restored by or-
ganic matters .
Finger and toe disease :
removed by lime
of plants absorbed in
proportion to
root surface
atmospheric
and mineral .
not in solution
in soils
not received
from a solution
rapidity and
duration of aec-
tion of
relation
phosphates
and nitrogen
compounds in
Formula for the chemical truths
in the agricultural letters

—

Food

of

G.

GERMAN agriculture before the
Thirty Years’ War

Graham—analysis of waters by

Grain, conditions for producing
largest crops of .

decrease in the condi-
tions for its growth

increase of, by means of
straw constituents

and straw unequal de-
velopment of

Grasses, underground growth of

—

pa

Green crops, effects of . :
_ — — thrive without ni-
trogenous ma-

nures

INDEX. 271
PAGE PAGE
11 Green manures, effects of 89

109 | Guano, comparison of, with hu-

itt man excrements weit

— effects of; not due to its
ammonia alone. 168
— experiments with. 60
67 — nature of ., 133

ii} — not a complete substi-

tute for human ex-

110 crements . 182
84 — quantity of, imported 179
84

H.
« MOT
HIGH FARMING, a rapid system
21 of spoliation . 148
Highwayman, on the Rhine,
30 system of 5 156
Hofmann, analysis of water by. 31
87 Hoskyns, opinion of 9
Human excrements, collection
of from towns 217
22 Humus, when useful 42
— ' former belief in the
value of . 41
Huxtable, observations of 57
170
264 iz
INDUCTIVE method applied to
agriculture. 8
— — triumphs of 8

153 | Irrigation, effect of, on injurious
31 organic matter - 85

101

K.
101
KROCKER, analysis of drainage
99 water by . ; -|~oa
Kuhlmann, experiments with

100 salts ofammonia by . 61

224
V7 L.

LAND, cause of unequal pro-
77 ductiveness of . : . 66

2/2. INDEX.
PAGE PAGE
Lawes, experiments of, with Mineral matters, restoration of 124
ammonia and mineral Moisture, attraction of soils for 38
matters - ‘ gos Aes Gl _ condensation of, in
Leaf-surface, effect of | on soils attended by
amount of nitrogen absorp- evolution of heat . 39
tion 76 — supply of. 40
Leguminous plants, ‘amount of Molasses, residue from, used as
nitrogen in 74 manure : . 169
Lemna “trisulea, analysis of ash Mud from pools, &e., a fertilis-
of Ser 36 ing agent 37
Lime, a cure for injurious — — — effectsof. . 165
organic matter. . 85
M. N.
MANURES, effect of, on land, NITRATE of ammonia and
how properly es- ~ common - salt, i
timated . 173 with 5 47
— failure of supply of 183 Nitrates, effects of, on er ops 43
_ nature of 108 Nitrogen absorbed in propor-
— nitrogen of, deriv ed tion to root surface 58
from air (ig — compounds and phos-
— not always food for phates, relation be-
plants 55 tween . : . 11S
— proper supply of 82 = in different crops . . 74
— proportion of phos- — supposed loss of, in
phates to nitro- rotten manure. . 131
gen in 172 oo the supposed active
— value of, estimated ingredient in salts
by nitrogen pre- of ammonia . 42
sent . 170 — theory of manures
Maremma : A ; , tL 115, 170
Meadows, vegetation of, depen- Nitrogenised products in plants
dent on underground suckers 72 proportional to leaf surface 76
Mecklenburgh, agriculture of . 157 | Nitrogenous manures for cereals 174
Miller, analysis of waters by 31 — manures when use-
Minas Geraes, agriculture of 148 roe st : 81
Mineral food, all elements of, — manures, effect of
possess equal value a on plants with
Mineral matters, activity of, in- large leaves 76
creased by salts Nutrition of plants, present view
of ammonia, Chili- of : 4 ‘ F . 24
saltpetre, &e. 65
— — importance of, in 0.
Lawes’ experi-
ments . 61 Oats, remunerative crop of 94
— — _ necessary to ani- Offenbach, Green Doctor of 12
mals. . 114 Oil mills, residue from . 180
— — in soils not inex- Organic matter, not a source of
haustible . 116, 130 fertility in itself . 118

INDEX. 273
PAGE PAGE
Organic substances’ destroyed Plants, possess a power of se-
by irrigation 85 lecting food 35
—_ — destroyedbylime 85 oo present view of mode
— — insoils frequently of nutrition of,
acause of dis- erroneous 24
ease : 84 | Pliny, opinions of, on agricul-
— — not exhausted by ture. . 193
cultivation . 110 | Potashin plants and drain: water
— — when useful in compared 33
soils . . 14,76 — removed by beet and
potatoes . 182
— salts rapidly decom-
Pi posed by soils - 52
— and soda salts differ-
PERENNIALS, absorption of food ently acted on by
by ‘ ye Sra b soils 52
Phlogiston ‘ 197 | Potassium, chloride of, action of
Phosphoric acid, in what forms soil on é = 26
present in soil 96 | Potatoes, minerals removed by 182
_ — not present in — phosphoric acid re-
drain, river, or moved by. 102
well water 34 | Poudrette, relation of phos-
— — quantity removed phates to nitrogen in . 172
by clover and Practical agriculturists, their
potatoes 102 sensibility to opposition 18
Phosphate of lime, action of soil Practical instructions, to be
on. 25 always preceded by theoreti-
— — — how distributed cal , ‘ ‘ : . 207
through soils . 97 Practical teachers, false reason-
Phosphate of magnesia, action ing of . 3 : pgs Ly
ofsoilon . 25 | Prize questions in agriculture
Phosphates, loss of by the valueless ; Res |
soil . 176 Progress based on experience,
— removed by potatoes 102 hmited : ; 5 eon fi
— and nitrogen in Pusey, opinions of . 3 oe
food etl
Plants, gee of nitrogen
, 74 R.
— ecmiliteaae of the life of 21
— general constituents of REMUNERATIVE crops, how de-
ash of . 20 termined - 98
— deep and shallow root- River water, analysis of . a
ing, object in cultivat- ' | Rocks, disintegration of . - 122
me .. ‘ 104, 152 Rome, the cause of the exhaus-
— mineral constituents of, tion of the lands of the
not received out of a ancient world. . 185
solution 30 | Roots, absorbent surface of 58
— nuiritionof . 22 — action of, on stones 35
— origin of combustible — protected by the action
portion of . 20 of the soil . 83

274.

PAGE
Rotation of crops, without re-
storation of minerals,
ultimate effects of . 143
—~ , valueel,.. . . . 142
Rye, remunerative cropof . 93

8.

SCHATTENMANN, experiments
with ammonia . - 60
Schubert, Knight of Cloverfield 155
Science confers power. 6

— the objects of, in agri-
culture. 211

— the results already ob-
tained by . : . 215
— true province of . ti

— value of, recognised hee AD
Scientific research, true mode of 15
_ teaching, rejection of 14
Silicates, how distributed
through soils ; Pei a
Soda, nitrate of, effects of 52, 55
_- —_—- — experiments with 47
Soda salts only partially de-

composed by soils . ‘ 53
Sodium, chloride of, action of
soils on io 6
_ — effects of, on
crops. . 43

Soils, action of, on solution of
chloride of-potassium . 26
— action of, on solution of
chloride of sodium 726
— analysis of, in Prussia . 116
— attraction of, for moisture 38
— cooled by evaporation . 89
— effects of, on solutions of
ammonia, potash, phos-
phorie, and silicic acids
limited ‘ 28
— effects of, on solutions of
salts indispensable to
plants. 25, 26
— effects of, on solutions of
salts not indispensable
to plants. ‘ 25
— eight elements required
by plants in , BOR:

INDEX.

PAGE
Soils, exhaustion of, by removal
of minerals without re-
storation . 67
— fertility of, dependent on
quantity of soluble
mineral matters present 65
— fertility of, not dependent
on nitrogen or organic
matter - ATS
— mechanical division of . 89
— mineral matters of, in-

soluble in water . = Sb
— productiveness of, how
estimated . 90

— progressive exhaustion of 103
— rich in organic matter,

effect of -< 29
— warmed by absorbing
moisture. : . 39
Special law . on
Stercutius, god of manure . 155
Subsoil, food derived from . 104
Suckers, underground, import-
aince of ; 72

Sulphur compounds and “phos-
phates, relation between .. 114

Sulphur and nitrogen organic
compounds . : ‘ LS

c.

TEMPERATURE Of soils, elevation
of, by condensation of mois-

ture. : ; . 40
Thames water . : : rae §
Theory . 7
Theoretical and practical teach-

ing, not useful together . 207
Thomson, observations of . 0 OT
Tobacco, minerals removed by 183
Trader, the objects ofa . ele
Turnip, finger and toe disease

in : : 2 ; 2, 82

Vis

VARRO, opinions of, on agricul-
ture... - : : . 192

INDEX. 275
PAGE PAGE
Vine-dresser, his mode of im- Walz on the nature of manure . 135

proving his soil . 184 — — the necessity for pro-
Vines, exhausting to land . 154 ducing manure... 129
Virgil, fo of, on agricul- — opinions of, on arable soils 122

ture. ‘ : . 192 — on the restoration of
minerals : . . 124
— on the value of fresh manure 133

W. Water plants receive food from
solution 35

WALz on the causes of fertility Waters, river and well, analysis
in a soil. 135 of 31

— — diminution of volume Way, analysis of drainage ‘water
of soils . 126 by : ‘ ‘ 2 oa
— — disintegration of rocks 122 — observations of . : oe OBE
— — exhaustion of soils . 123 | Wetterau, farmer . : « BBS
— — guano. ‘ . 134 | Wheat-field, when exhausted . 93
— — the loss of nitrogen in Writers on practical agriculture 121

manure heaps . . 131
THE END. ~-

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8.—THE BEAUTIES OF RUSKIN;

Or, the True and the Beautiful in Nature, Art, Morals, and Religion. Selected from the
works of John Ruskin, with a notice of the author. By Mrs. L. C. Tuthill. 1 vol. $1 26.
' This elegant volume, though composed only of extracts, has been so handled, as to

ossess all the interest of a continuous work on Art, etc., arranged in chapters, without
ts technicalitics, making it an agreeable companion to the Drawing Room.

“The author is an enthusiast, and inspires the reader with his own intense love for the
True and the Good. It would be well to make this work a study in schools and
colleges,"— WV. Y. Observer.

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