Produced by Steven Giacomelli, Brownfox and the Online
Distributed Proofreading Team at https://www.pgdp.net (This
file was produced from images produced by Core Historical
Literature in Agriculture (CHLA), Cornell University)
TRANSCRIBERS' NOTES
Most pages of the book include at the bottom a number of questions for
the student to consider. These have been retained in this version and
enclosed in square brackets.
Some corrections to typographical errors have been made. These are
recorded at the end of the text.
* * * * *
G. E. WARING, JR.
Consulting Agriculturist.
ACCURATE ANALYSES OF SOILS, MANURES, AND
CROPS PROCURED. FARMS VISITED,
TREATMENT RECOMMENDED,
ETC.
Letters of advice on analyses will be written for those who require
them, for $25 each.
Letters on other branches of the subject, inclosing a suitable fee, will
receive prompt attention.
OFFICE, 143 FULTON-STREET, NEW YORK, (UP STAIRS.
POST-OFFICE ADDRESS, RYE, N. Y.
DR. CHARLES ENDERLIN,
ANALYTICAL AND CONSULTING
Chemist,
84 WALKER-STREET,
NEW YORK.
ANALYSIS OF MINERALS, SOILS,--ORGANIC ANALYSIS, ETC.
D. APPLETON & COMPANY
HAVE IN COURSE OF PREPARATION,
THE
EARTHWORKER;
OR,
Book of Husbandry.
BY G. E. WARING, JR.
AUTHOR OF THE "ELEMENTS OF AGRICULTURE."
This book is intended as a sequel to the Elements of Agriculture, being
a larger and more complete work, containing fuller directions for the
treatment of the different kinds of soils, for the _preparation of
manures_, and especially for the drainage of lands, whether level,
rolling, hilly, or springy. Particular attention will be paid to the use
of analysis. The feeding of different animals, and the cultivation of
the various crops, will be described with care.
The size of the work will be about 400 pp. 8vo., and it will probably be
published January 1st, 1856. Price $1. Orders sent to the publishers, or
to the author, at Rye, N. Y., will be supplied in the order in which
they are received.
ELEMENTS
OF
AGRICULTURE
Extract from a letter to the author from Prof. Mapes, editor of the
_Working Farmer_:
* * * "After a perusal of your manuscript, I feel authorized in
assuring you that, for the use of young farmers, and schools,
your book is superior to any other elementary work extant. JAMES
J. MAPES."
* * * * *
Letter from the Editor of the N. Y. Tribune:
MY FRIEND WARING,
If all who need the information given in your _Elements of
Agriculture_ will confess their ignorance as frankly as I do,
and seek to dispel it as promptly and heartily, you will have
done a vast amount of good by writing it. * * * * * I have found
in every chapter important truths, which I, as a
would-be-farmer, needed to know, yet which I _did not_ know, or
had but a confused and glimmering consciousness of, before I
read your lucid and straightforward exposition of the bases of
Agriculture as a science. I would not have my son grow up as
ignorant of these truths as I did for many times the price of
your book; and, I believe, a copy of that book in every family
in the Union, would speedily add at least ten per cent. per acre
to the aggregate product of our soil, beside doing much to stem
and reverse the current which now sets so strongly away from the
plow and the scythe toward the counter and the office. Trusting
that your labors will be widely regarded and appreciated,
I remain yours truly,
HORACE GREELEY.
New York, June 23, 1854.
THE
ELEMENTS OF AGRICULTURE:
A Book for Young Farmers,
WITH QUESTIONS PREPARED FOR THE USE OF
SCHOOLS.
BY
GEO. E. WARING, JR.,
CONSULTING AGRICULTURIST.
The effort to extend the dominion of man over nature is the most healthy
and most noble of all ambitions.--BACON.
NEW YORK:
D. APPLETON AND COMPANY,
346 & 348 BROADWAY.
M DCCC LIV.
Entered according to Act of Congress, in the year 1854, by
GEO. E. WARING, JR.,
in the Clerk's Office of the District Court of the United States for the
Southern District of New York.
TO
MY FRIEND AND TUTOR,
PROF. JAMES J. MAPES,
THE PIONEER OF AGRICULTURAL SCIENCE IN AMERICA,
This Book
IS RESPECTFULLY DEDICATED
BY HIS PUPIL,
THE AUTHOR.
TO THE STUDENT.
This book is presented to you, not as a work of science, nor as a dry,
chemical treatise, but as a plain statement of the more simple
operations by which nature produces many results, so common to our
observation, that we are thoughtless of their origin. On these results
depend the existence of man and the lower animals. No man should be
ignorant of their production.
In the early prosecution of the study, you will find, perhaps, nothing
to relieve its tediousness; but, when the foundation of agricultural
knowledge is laid in your mind so thoroughly that you know the character
and use of every stone, then may your thoughts build on it fabrics of
such varied construction, and so varied in their uses, that there will
be opened to you a new world, even more wonderful and more beautiful
than the outward world, which exhibits itself to the senses. Thus may
you live two lives, each assisting in the enjoyment of the other.
But you may ask the _practical_ use of this. "The world is made up of
little things," saith the proverb. So with the productive arts. The
steam engine consists of many parts, each part being itself composed of
atoms too minute to be detected by our observation. The earth itself, in
all its solidity and life, consists entirely of atoms too small to be
perceived by the naked eye, each visible particle being an aggregation
of thousands of constituent elements. The crop of wheat, which the
farmer raises by his labor, and sells for money, is produced by a
combination of particles equally small. They are not mysteriously
combined, nor irregularly, but each atom is taken from its place of
deposit, and carried to its required location in the living plant, by
laws as certain as those which regulate the motion of the engine, or the
revolutions of the earth.
It is the business of the practical farmer to put together these
materials, with the assistance of nature. He may learn her ways, assist
her action, and succeed; or he may remain ignorant of her operations,
often counteract her beneficial influences, and often fail.
A knowledge of the _inner_ world of material things about us will
produce pleasure to the thoughtful, and profit to the practical.
CONTENTS.
SECTION FIRST.
THE PLANT.
PAGE.
CHAPTER I.--Introduction, 11
" II.--Atmosphere, 15
" III.--Hydrogen, Oxygen, and Nitrogen, 23
" IV.--Inorganic Matter, 29
" V.--Growth, 40
" VI.--Proximate division of Plants, 43
" VII.--Location of the Proximates, and variations in the
Ashes of Plants, 52
" VIII.--Recapitulation, 56
SECTION SECOND.
THE SOIL.
CHAPTER I.--Formation and Character of the Soil, 65
" II.--Uses of Organic Matter, 77
" III.--Uses of Inorganic Matter, 84
SECTION THIRD.
MANURES.
CHAPTER I.--Character and varieties of Manure, 93
" II.--Excrements of Animals, 96
" III.--Waste of Manure, 101
" IV.--Absorbents, 109
" V.--Composting Stable Manure, 118
" VI.--Different kinds of Animal Excrement, 126
" VII.--Other Organic Manures, 136
" VIII.--Mineral Manures, 149
" IX.--Deficiencies of Soils, means of Restoration, etc., 155
" X.--Atmospheric Fertilizers, 197
" XI.--Recapitulation, 203
SECTION FOURTH.
MECHANICAL CULTIVATION.
CHAPTER I.--Mechanical Character of the Soil, 209
" II.--Under-draining, 211
" III.--Advantages of Under-draining, 217
" IV.--Sub-soil Plowing, 232
" V.--Plowing and other modes of Pulverizing the Soil, 239
" VI.--Rolling, Mulching, Weeding, etc., 245
SECTION FIFTH.
ANALYSIS.
CHAPTER I.--Nature of Analysis, 259
" II.--Tables of Analysis, 264
THE PRACTICAL FARMER, 279
EXPLANATION OF TERMS, 287
SECTION FIRST.
THE PLANT.
CHAPTER I.
INTRODUCTION.
[What is the object of cultivating the soil?
What is necessary in order to cultivate with economy?
Are plants created from nothing?]
The object of cultivating the soil is to raise from it a crop of
_plants_. In order to cultivate with economy, we must _raise the largest
possible quantity with the least expense, and without permanent injury
to the soil_.
Before this can be done we must study the character of plants, and learn
their exact composition. They are not _created_ by a mysterious power,
they are merely made up of matters already in existence. They take up
water containing food and other matters, and discharge from their roots
those substances that are not required for their growth. It is necessary
for us to know what kind of matter is required as food for the plant,
and where this is to be obtained, which we can learn only through such
means as shall separate the elements of which plants are composed; in
other words, we must _take them apart_, and examine the different pieces
of which they are formed.
[What must we do to learn the composition of plants?
What takes place when vegetable matter is burned?
What do we call the two divisions produced by burning?
Where does organic matter originate? Inorganic?
How much of chemistry should farmers know?]
If we burn any vegetable substance it disappears, except a small
quantity of earthy matter, which we call _ashes_. In this way we make an
important division in the constituents of plants. One portion dissipates
into the atmosphere, and the other remains as ashes.
That part which burns away during combustion is called _organic matter_;
the ashes are called _inorganic matter_. The organic matter has become
air, and hence we conclude that it was originally obtained from air. The
inorganic matter has become earth, and was obtained from the soil.
This knowledge can do us no good except by the assistance of chemistry,
which explains the properties of each part, and teaches us where it is
to be found. It is not necessary for farmers to become chemists. All
that is required is, that they should know enough of chemistry to
understand the nature of the materials of which their crops are
composed, and how those materials are to be used to the best advantage.
This amount of knowledge may be easily acquired, and should be possessed
by every person, old or young, whether actually engaged in the
cultivation of the soil or not. All are dependent on vegetable
productions, not only for food, but for every comfort and convenience of
life. It is the object of this book to teach children the first
principles of agriculture: and it contains all that is absolutely
necessary to an understanding of the practical operations of
cultivation, etc.
[Is organic matter lost after combustion?
Of what does it consist?
How large a part of plants is carbon?]
We will first examine the _organic_ part of plants, or that which is
driven away during combustion or burning. This matter, though apparently
lost, is only changed in form.
It consists of one solid substance, _carbon_ (or charcoal), and three
gases, _oxygen_, _hydrogen_ and _nitrogen_. These four kinds of matter
constitute nearly the whole of most plants, the ashes forming often less
than one part in one hundred of their dry weight.
[What do we mean by gas?
Does oxygen unite with other substances?
Give some instances of its combinations]
When wood is burned in a close vessel, or otherwise protected from the
air, its carbon becomes charcoal. All plants contain this substance, it
forming usually about one half of their dry weight. The remainder of
their organic part consists of the three gases named above. By the word
gas, we mean _air_. Oxygen, hydrogen and nitrogen, when pure, are always
in the form of air. Oxygen has the power of uniting with many
substances, forming compounds which are different from either of their
constituents alone. Thus: oxygen unites with _iron_ and forms oxide of
iron or _iron-rust_, which does not resemble the gray metallic iron nor
the gas oxygen; oxygen unites with carbon and forms carbonic acid, which
is an invisible gas, but not at all like pure oxygen; oxygen combines
with hydrogen and forms water. All of the water, ice, steam, etc., are
composed of these two gases. We know this because we can artificially
decompose, or separate, all water, and obtain as a result simply oxygen
and hydrogen, or we can combine these two gases and thus form pure
water; oxygen combines with nitrogen and forms nitric acid. These
chemical changes and combinations take place only under certain
circumstances, which, so far as they affect agriculture, will be
considered in the following pages.
As the organic elements of plants are obtained from matters existing in
the atmosphere which surrounds our globe, we will examine its
constitution.
CHAPTER II.
ATMOSPHERE.
[What is atmospheric air composed of?
In what proportions?
What is the use of nitrogen in air?
Does the atmosphere contain other matters useful to vegetation?
What are they?]
Atmospheric air is composed of oxygen and nitrogen. Their proportions
are, one part of oxygen to four parts of nitrogen. Oxygen is the active
agent in the combustion, decay, and decomposition of organized bodies
(those which have possessed animal or vegetable life, that is, organic
matter), and others also, in the breathing of animals. Experiments have
proved that if the atmosphere consisted of pure oxygen every thing would
be speedily destroyed, as the processes of combustion and decay would be
greatly accelerated, and animals would be so stimulated that death would
soon ensue. The use of the nitrogen in the air is to _dilute_ the
oxygen, and thus reduce the intensity of its effect.
Besides these two great elements, the atmosphere contains certain
impurities which are of great importance to vegetable growth; these are,
_carbonic acid, water, ammonia, etc._
CARBONIC ACID.
[What is the source of the carbon of plants?
What is carbonic acid?
What is its proportion in the atmosphere?
Where else is it found?
How does it enter the plant?
What are the offices of leaves?]
Carbonic acid is in all probability the only source of the carbon of
plants, and consequently is of more importance to vegetation than any
other single sort of food. It is a gas, and is not, under natural
circumstances, perceptible to our senses. It constitutes about 1/2500 of
the atmosphere, and is found in combination with many substances in
nature. Marble, limestone and chalk, are carbonate of lime, or carbonic
acid and lime in combination; and carbonate of magnesia is a compound of
carbonic acid and magnesia. This gas exists in combination with many
other mineral substances, and is contained in all water not recently
boiled. Its supply, though small, is sufficient for the purposes of
vegetation. It enters the plant in two ways--through the roots in the
water which goes to form the sap, and at the leaves, which absorb it
from the air in the form of gas. The leaf of the plant seems to have
three offices: that of absorbing carbonic acid from the atmosphere--that
of assisting in the chemical preparation of the sap--and that of
evaporating its water. If we examine leaves with a microscope we shall
find that some have as many as 170,000 openings, or mouths, in a square
inch; others have a much less number. Usually, the pores on the under
side of the leaf absorb the carbonic acid. This absorptive power is
illustrated when we apply the lower side of a cabbage leaf to a wound,
as it draws strongly--the other side of the leaf has no such action.
Young sprouts may have the power of absorbing and decomposing carbonic
acid.
[What parts of roots absorb food?
How much of their carbon may plants receive through their roots?
What change does carbonic acid undergo after entering the plant?
In what parts of the plant, and under what influence, is carbonic acid
decomposed?]
The roots of plants terminate at their ends in minute spongioles, or
mouths for the absorption of fluids containing nutriment. In these
fluids there exist greater or less quantities of carbonic acid, and a
considerable amount of this gas enters into the circulation of the
plants and is carried to those parts where it is required for
decomposition. Plants, under favorable circumstances, may thus obtain
about one-third of their carbon.
Carbonic acid, it will be recollected, consists of _carbon and oxygen_,
while it supplies only _carbon_ to the plant. It is therefore necessary
that it be divided, or decomposed, and that the carbon be retained while
the oxygen is sent off again into the atmosphere, to reperform its
office of uniting with carbon. This decomposition takes place in the
_green_ parts of plants and only under the influence of daylight. It is
not necessary that the sun shine directly on the leaf or green shoot,
but this causes a _more rapid_ decomposition of carbonic acid, and
consequently we find that plants which are well exposed to the sun's
rays make the most rapid growth.
[Explain the condition of different latitudes.
Does the proportion of carbonic acid in the atmosphere remain about the
same?]
The fact that light is essential to vegetation explains the conditions
of different latitudes, which, so far as the assimilation of carbon is
concerned, are much the same. At the Equator the days are but about
twelve hours long. Still, as the growth of plants is extended over eight
or nine months of the year, the duration of daylight is sufficient for
the requirements of a luxuriant vegetation. At the Poles, on the
contrary, the summer is but two or three months long; here, however, it
is daylight all summer, and plants from continual growth develop
themselves in that short time.
It will be recollected that carbonic acid constitutes but about 1/2500
of the air, yet, although about one half of all the vegetable matter in
the world is derived from this source, as well as all of the carbon
required by the growth of plants, its proportion in the atmosphere is
constantly about the same. In order that we may understated this, it
becomes necessary for us to consider the means by which it is formed.
Carbon, by the aid of fire, is made to unite with oxygen, and always
when bodies containing carbon are burnt _with the presence of
atmospheric air_, the oxygen of that air unites with the carbon, and
forms carbonic acid. The same occurs when bodies containing carbon
_decay_, as this is simply a slower _burning_ and produces the same
results. The respiration (or breathing) of animals is simply the union
of the carbon of the blood with the oxygen of the air drawn into the
lungs, and their breath, when thrown out, always contains carbonic acid.
From this we see that the reproduction of this gas is the direct effect
of the destruction of all organized bodies, whether by fire, decay, or
consumption by animals.
[Explain some of the operations in which this reproduction
takes place.
How is it reproduced?]
Furnaces are its wholesale manufactories. Every cottage fire is
continually producing a new supply, and the blue smoke issuing from the
cottage-chimney, as described by so many poets, possesses a new beauty,
when we reflect that besides indicating a cheerful fire on the hearth,
it contains materials for making food for the cottager's tables and new
faggots for his fire. The wick of every burning lamp draws up the carbon
of the oil to be made into carbonic acid at the flame. All matters in
process of combustion, decay, fermentation, or putrefaction, are
returning to the atmosphere those constituents, which they obtained from
it. Every living animal, even to the smallest insect, by respiration,
spends its life in the production of this material necessary to the
growth of plants, and at death gives up its body in part for such
formation by decay.
Thus we see that there is a continual change from the carbon of plants
to air, and from air back to plants, or through them to animals. As each
dollar in gold that is received into a country permanently increases its
amount of circulating medium, and each dollar sent out permanently
decreases it until returned, so the carbonic acid sent into the
atmosphere by burning, decay, or respiration, becomes a permanent stock
of constantly changeable material, until it shall be locked up for a
time, as in a house which may last for centuries, or in an oak tree
which may stand for thousands of years. Still, at the decay of either of
these, the carbon which they contain must be again resolved into
carbonic acid.
[What are the coal-beds of Pennsylvania?
What are often found in them?]
The coal-beds of Pennsylvania are mines of carbon once abstracted from
the atmosphere by plants. In these coal-beds are often found fern
leaves, toads, whole trees, and in short all forms of organized matter.
These all existed as living things before the great floods, and at the
breaking away of the barriers of the immense lakes, of which our present
lakes were merely the deep holes in their beds, they were washed away
and deposited in masses so great as to take fire from their chemical
changes. It is by many supposed that this fire acting throughout the
entire mass (without the presence of air _to supply oxygen_ except on
the surface) caused it to become melted carbon, and to flow around those
bodies which still retained their shapes, changing them to coal without
destroying their structures. This coal, so long as it retains its
present form, is lost to the vegetable kingdom, and each ton that is
burned, by being changed into carbonic acid, adds to the ability of the
atmosphere to support an increased amount of vegetation.
[Explain the manner in which they become coal.
How does the burning of coal benefit vegetation?
Is carbon ever permanent in any of its forms?
What enables it to change its condition?]
Thus we see that, in the provisions of nature, carbon, the grand basis,
on which all organized matter is founded, is never permanent in any of
its forms. Oxygen is the carrier which enables it to change its
condition. For instance, let us suppose that we have a certain quantity
of charcoal; this is nearly pure carbon. We ignite it, and it unites
with the oxygen of the air, becomes carbonic acid, and floats away into
the atmosphere. The wind carries it through a forest, and the leaves of
the trees with their millions of mouths drink it in. By the assistance
of light it is decomposed, the oxygen is sent off to make more carbonic
acid, and the carbon is retained to form a part of the tree. So long as
that tree exists in the form of wood, the carbon will remain unaltered,
but when the wood decays, or is burned, it immediately takes the form of
carbonic acid, and mingles with the atmosphere ready to be again taken
up by plants, and have its carbon deposited in the form of vegetable
matter.
[Give an instance of such change.
How do plants and animals benefit each other?
Describe the experiment with the glass tube.]
The blood of animals contains carbon derived from their food. This
unites with the oxygen of the air drawn into the lungs and forms
carbonic acid. Without this process, animals could not live. Thus, while
by the natural operation of breathing, they make carbonic acid for the
uses of the vegetable world, plants, in taking up carbon, throw off
oxygen to keep up the life of animals. There is perhaps no way in which
we can better illustrate the changes of form in carbon than by
describing a simple experiment.
Take a glass tube filled with oxygen gas, and put in it a lump of
charcoal, cork the ends of the tube tightly, and pass through the corks
the wires of an electrical battery. By passing a stream of electrical
fluid over the charcoal it may be ignited, when it will burn with great
brilliancy. In burning it is dissolved in the oxygen forming carbonic
acid, and disappears. It is no more lost, however, than is the carbon of
wood which is burned in a stove; although invisible, it is still in the
tube, and may be detected by careful weighing. A more satisfactory proof
of its presence may be obtained by _decomposing_ the carbonic acid by
drawing the wires a short distance apart, and giving a _spark_ of
electricity. This immediately separates the oxygen from the carbon which
forms a dense black smoke in the tube. By pushing the corks together we
may obtain a wafer of charcoal of the same weight as the piece
introduced. In this experiment we have changed carbon from its solid
form to an invisible gas and back again to a solid, thus fully
representing the continual changes of this substance in the destruction
of organic matter and the growth of plants.
CHAPTER III.
HYDROGEN, OXYGEN AND NITROGEN.
HYDROGEN AND OXYGEN.
[What is water composed of?
If analyzed, what does it yield?
How do plants obtain their hydrogen and oxygen?]
Let us now consider the three gases, _hydrogen_, _oxygen_ and
_nitrogen_, which constitute the remainder of the organic part of
plants.
Hydrogen and oxygen compose _water_, which, if analyzed, yields simply
these two gases. Plants perform such analysis, and in this way are able
to obtain a sufficient supply of these materials, as their sap is
composed chiefly of water. Whenever vegetable matter is destroyed by
burning, decay, or otherwise, its hydrogen and oxygen unite and form
water, which is parted with usually in the form of an invisible vapor.
The atmosphere of course contains greater or less quantities of watery
vapor arising from this cause and from the evaporation of liquid water.
This vapor condenses, forming rains, etc.
Hydrogen and oxygen are never taken into consideration in manuring
lands, as they are so readily obtained from the water constituting the
sap of the plant, and consequently should not occupy our attention in
this book.
NITROGEN.
[If vegetable matter be destroyed, what becomes of these
constituents?
What is the remaining organic constituent?
Why is it worthy of close attention?
Do plants appropriate the nitrogen of the atmosphere?]
_Nitrogen_, the only remaining _organic_ constituent of vegetable
matter, is for many reasons worthy of close attention.
1. It is necessary to the growth and perfection of all cultivated
plants.
2. It is necessary to the formation of animal muscle.
3. It is often deficient in the soil.
4. It is liable to be easily lost from manures.
Although about four fifths of atmospheric air are pure nitrogen, it is
almost certain that plants get no nutriment at all from this source. It
is all obtained from some of its compounds, chiefly from the one called
ammonia. Nitric acid is also a source from which plants may obtain
nitrogen, though to the farmer of less importance than ammonia.
AMMONIA.
[What is the principal source from which they obtain nitrogen?
What is ammonia?
How is it formed?
Where does it always exist?
How do plants take up ammonia?]
_Ammonia_ is composed of nitrogen and hydrogen. It has a pungent smell
and is familiarly known as _hartshorn_. The same odor is perceptible
around stables and other places where animal matter is decomposing. All
animal muscle, certain parts of plants, and other organized substances,
consist of compounds containing nitrogen. When these compounds undergo
combustion, or are in any manner decomposed, the nitrogen which they
contain usually unites with hydrogen, and forms ammonia. In consequence
of this the atmosphere always contains more or less of this gas, arising
from the decay, etc., which is continually going on all over the world.
This ammonia in the atmosphere is the capital stock to which all plants,
not artificially manured, must look for their supply of nitrogen. As
they can take up ammonia only through their roots, we must discover
some means by which it may be conveyed from the atmosphere to the soil.
[Does water absorb it?
What is _spirits of hartshorn_?
Why is this power of water important in agriculture?
What instance may be cited to prove this?]
Water may be made to absorb many times its bulk of this gas, and water
with which it comes in contact will immediately take it up. Spirits of
hartshorn is merely water through which ammonia has been passed until it
is saturated.[A] This power of water has a direct application to
agriculture, because the water constituting rains, dews, &c., absorbs
the ammonia which the decomposition of nitrogenous matter had sent into
the atmosphere, and we find that all rain, snow and dew, contain
ammonia. This fact may be chemically proved in various ways, and is
perceptible in the common operations of nature. Every person must have
noticed that when a summer's shower falls on the plants in a flower
garden, they commence their growth with fresh vigor while the blossoms
become larger and more richly colored. This effect cannot be produced by
watering with spring water, unless it be previously mixed with ammonia,
in which case the result will be the same.
Although ammonia is a gas and pervades the atmosphere, few, if any,
plants can take it up, as they do carbonic acid, through their leaves.
It must all enter through the roots in solution in the water which goes
to form the sap. Although the amount received from the atmosphere is of
great importance, there are few cases where artificial applications are
not beneficial. The value of farm-yard and other animal manures, depends
chiefly on the ammonia which they yield on decomposition. This subject,
also the means for retaining in the soil the ammoniacal parts of
fertilizing matters, will be fully considered in the section on manures.
[Can plants use more ammonia than is received from the
atmosphere?
On what does the value of animal manure chiefly depend?
What changes take place after ammonia enters the plant?
May the same atom of nitrogen perform many different offices?]
After ammonia has entered the plant it may be decomposed, its hydrogen
sent off, and its nitrogen retained to answer the purposes of growth.
The changes which nitrogen undergoes, from plants to animals, or, by
decomposition, to the form of ammonia in the atmosphere, are as varied
as those of carbon and the constituents of water. The same little atom
of nitrogen may one year form a part of a plant, and the next become a
constituent of an animal, or, with the decomposed dead animal, may form
a part of the soil. If the animal should fall into the sea he may become
food for fishes, and our atom of nitrogen may form a part of a fish.
That fish may be eaten by a larger one, or at death may become food for
the whale, through the marine insect, on which it feeds. After the
abstraction of the oil from the whale, the nitrogen may, by the
putrefaction of his remains, be united to hydrogen, form ammonia, and
escape into the atmosphere. From here it may be brought to the soil by
rains, and enter into the composition of a plant, from which, could its
parts speak as it lies on our table, it could tell us a wonderful tale
of travels, and assure us that, after wandering about in all sorts of
places, it had returned to us the same little atom of nitrogen which we
had owned twenty years before, and which for thousands of years had been
continually going through its changes.
[Is the same true of the other constituents of plants?
Is any atom of matter ever lost?]
The same is true of any of the organic or inorganic constituents of
plants. They are performing their natural offices, or are lying in the
earth, or floating in the atmosphere, ready to be lent to _any_ of their
legitimate uses, sure again to be returned to their starting point.
Thus no atom of matter is ever lost. It may change its place, but it
remains for ever as a part of the capital of nature.
FOOTNOTES:
[A] By _saturated_, we mean that it contains all that it is capable of
holding.
CHAPTER IV.
INORGANIC MATTER.
[What are ashes called?
How many kinds of matter are there in the ashes of plants?
Into what three classes may they be divided?
What takes place when alkalies and acids are brought together?]
We will now examine the ashes left after burning vegetable substances.
This we have called inorganic matter, and it is obtained from the soil.
Organic matter, although forming so large a part of the plant, we have
seen to consist of four different substances. The inorganic portion, on
the contrary, although forming so small a part, consists of no less than
_nine_ or _ten_ different kinds of matter.[B] These we will consider in
order. In their relations to agriculture they may be divided into
_three_ classes--_alkalies_, _acids_, and _neutrals_.[C]
[Is the character of a compound the same as that of its
constituents?
Give an instance of this.
Do neutrals combine with other substances?
Name the four alkalies found in the ashes of plants.]
Alkalies and acids are of opposite properties, and when brought together
they unite and neutralize each other, forming compounds which are
neither alkaline nor acid in their character. Thus, carbonic acid (a
gas,) unites with lime--a burning, caustic substance--and forms marble,
which is a hard tasteless stone. Alkalies and acids are characterized
by their desire to unite with each other, and the compounds thus formed
have many and various properties, so that the characters of the
constituents give no indication of the character of the compound. For
instance, lime causes the gases of animal manure to escape, while
sulphate of lime (a compound of sulphuric acid and lime) produces an
opposite effect, and prevents their escape.
The substances coming under the signification of neutrals, are less
affected by the laws of combination, still they often combine feebly
with other substances, and some of the resultant compounds are of great
importance to agriculture.
ALKALIES.
The alkalies which are found in the ashes of plants are four in number;
they are _potash_, _soda_, _lime_ and _magnesia_.
POTASH.
[How may we obtain potash from ashes?
What are some of its agricultural uses?]
When we pour water over wood ashes it dissolves the _potash_ which they
contain, and carries it through in solution. This solution is called
_ley_, and if it be boiled to dryness it leaves a solid substance from
which pure potash may be made. Potash left exposed to the air absorbs
carbonic acid and becomes carbonate of potash, or _pearlash_; if another
atom of carbonic acid be added, it becomes super-carbonate of potash, or
_salaeratus_. Potash has many uses in agriculture.
1. It forms a constituent of nearly all plants.
2. It unites with silica (a neutral), and forms a compound which water
can dissolve and carry into the roots of plants; thus supplying them
with an ingredient which gives them much of their strength.[D]
3. It is a strong agent in the decomposition of vegetable matter, and is
thus of much importance in preparing manures.
4. It roughens the smooth round particles of sandy soils, and prevents
their compacting, as they are often liable to do.
5. It is also of use in killing certain kinds of insects, and, when
artificially applied, in smoothing the bark of fruit trees.
The source from which this and the other inorganic matters required are
to be obtained, will be fully considered in the section on manures.
SODA.
[Where is soda found most largely?
What is Glauber's salts?
What is washing soda?
What are some of the uses of lime?]
_Soda_, one of the alkalies contained in the ashes of plants, is very
much the same as potash in its agricultural character. Its uses are the
same as those of potash--before enumerated. Soda exists very largely in
nature, as it forms an important part of common salt, whether in the
ocean or in those inland deposits known as rock salt. When combined with
sulphuric acid it forms sulphate of soda or _Glauber's salts_. In
combination with carbonic acid, as carbonate of soda, it forms the
common washing soda of the shops. It is often necessary to render soils
fertile.
LIME.
_Lime_ is in many ways important in agriculture:
1. It is a constituent of plants and animals.
2. It assists in the decomposition of vegetable matter in the soil.
3. It corrects the acidity[E] of sour soils.
4. As chloride or sulphate of lime it is a good absorbent of fertilizing
gases.
[How is caustic lime made?
How much carbonic acid is thus liberated?
How does man resemble Sinbad the sailor?]
In nature it usually exists in the form of carbonate of lime: that is,
as marble, limestone, and chalk--these all being of the same
composition. In manufacturing caustic (or quick) lime, it is customary
to burn the carbonate of lime in a kiln; by this means the carbonic acid
is thrown off into the atmosphere and the lime remains in a pure or
caustic state. A French chemist states that every cubic yard of
limestone that is burned, throws off _ten thousand_ cubic yards of
carbonic acid, which may be used by plants. This reminds us of the story
of Sinbad the sailor, where we read of the immense _genie_ who came out
of a very small box by the sea-shore, much to the surprise of Sinbad,
who could not believe his eyes, until the _genie_ changed himself into a
cloud of smoke and went into the box again. Sinbad fastened the lid, and
the _genie_ must have remained there until the box was destroyed.
Now man is very much like Sinbad, he lets the carbonic acid out from the
limestone (when it expands and becomes a gas); and then he raises a
crop, the leaves of which drink it in and pack the carbon away in a very
small compass as vegetable matter. Here it must remain until the plant
is destroyed, when it becomes carbonic acid again, and occupies just as
much space as ever.
The burning of limestone is a very prolific source of carbonic acid.
MAGNESIA.
[What do you know about magnesia?
What is phosphoric acid composed of?
With what substance does it form its most important compound?]
_Magnesia_ is the remaining alkali of vegetable ashes. It is well known
as a medicine, both in the form of calcined magnesia, and, when mixed
with sulphuric acid, as epsom salts.
Magnesia is necessary to nearly all plants, but too much of it is
poisonous, and it should be used with much care, as many soils already
contain a sufficient quantity. It is often found in limestone rocks
(that class called _dolomites_), and the injurious effects of some kinds
of lime, as well as the barrenness of soils made from dolomites, may be
attributed entirely to the fact that they contain too much magnesia.
ACIDS.
PHOSPHORIC ACID.
_Phosphoric acid._--This subject is one of the greatest interest to the
farmer. Phosphoric acid is composed of phosphorus and oxygen. The end
of a loco-foco match contains phosphorus, and when it is lighted it
unites with the oxygen of the atmosphere and forms phosphoric acid; this
constitutes the white smoke which is seen for a moment before the
sulphur commences burning. Being an acid, this substance has the power
of combining with any of the alkalies. Its most important compound is
with lime.
[Will soils, deficient in phosphate of lime, produce good
crops?
From what source do plants obtain their phosphorus?]
_Phosphate of lime_ forms about 65 per cent. of the dry weight of the
bones of all animals, and it is all derived from the soil through the
medium of plants. As plants are intended as food for animals, nature has
provided that they shall not attain their perfection without taking up a
supply of phosphate of lime as well as of the other earthy matters;
consequently, there are many soils which will not produce good crops,
simply because they are deficient in phosphate of lime. It is one of the
most important ingredients of manures, and its value is dependent on
certain conditions which will be hereafter explained.
Another use of phosphoric acid in the plant is to supply it with a small
amount of _phosphorus_, which seems to be required in the formation of
the seed.
SULPHURIC ACID.
[What is sulphuric acid composed of?
What is plaster?
What is silica?
Why is it necessary to the growth of plants?
What compounds does it form with alkalies?]
_Sulphuric acid_ is important to vegetation and is often needed to
render soils fertile. It is composed of sulphur and oxygen, and is made
for manufacturing purposes, by burning sulphur. With lime it forms
_sulphate of lime_, which is gypsum or 'plaster.' In this form it is
often found in nature, and is generally used in agriculture. Other
important methods for supplying sulphuric acid will be described
hereafter. It gives _to_ the plant a small portion of _sulphur_, which
is necessary to the formation of some of its parts.
NEUTRALS.
SILICA.
[How can you prove its existence in corn stalks?
What instance does Liebig give to show its existence in grass?
How do we supply silicates?
Why does grain lodge?
What is the most important compound of chlorine?]
This is sand, the base of flint. It is necessary for the growth of all
plants, as it gives them much of their strength. In connection with an
alkali it constitutes the hard shining surface of corn stalks, straw,
etc. Silica unites with the alkalies and forms compounds, such as
_silicate of potash_, _silicate of soda, etc._, which are soluble in
water, and therefore available to plants. If we roughen a corn stalk
with sand-paper we may sharpen a knife upon it. This is owing to the
hard particles of silica which it contains. Window glass is silicate of
potash, rendered insoluble by additions of arsenic and litharge.
Liebig tells us that some persons discovered, between Manheim and
Heidelberg in Germany, a mass of melted glass where a hay-stack had been
struck by lightning. They supposed it to be a meteor, but chemical
analysis showed that it was only the compound of silica and potash which
served to strengthen the grass.
There is always _enough_ silica in the soil, but it is often necessary
to add an alkali to render it available. When grain, etc., lodge or fall
down from their own weight, it is altogether probable that they are
unable to obtain from the soil a sufficient supply of the soluble
silicates, and some form of alkali should be added to the soil to unite
with the sand and render it soluble.
CHLORINE.
[Of what use is chloride of lime?
What is oxide of iron?
What is the difference between the _per_oxide and the _prot_oxide of
iron?]
_Chlorine_ is an important ingredient of vegetable ashes, and is often
required to restore the balance to the soil. It is not found alone in
nature, but is always in combination with other substances. Its most
important compound is with sodium, forming _chloride of sodium_ (or
common salt). Sodium is the base of soda, and common salt is usually the
best source from which to obtain both soda and chlorine. Chlorine unites
with lime and forms _chloride of lime_, which is much used to absorb the
unpleasant odors of decaying matters, and in this character it is of use
in the treatment of manures.
OXIDE OF IRON.
_Oxide of iron_, one of the constituents of ashes, is common iron rust.
_Iron_ itself is naturally of a grayish color, but when exposed to the
atmosphere, it readily absorbs oxygen and forms a reddish compound. It
is in this form that it usually exists in nature, and many soils as well
as the red sandstones are colored by it. It is seldom, if ever,
necessary to apply this as a manure, there being usually enough of it in
the soil.
This red oxide of iron, of which we have been speaking, is called by
chemists the _peroxide_. There is another compound which contains less
oxygen than this, and is called the _protoxide of iron_, which is
poisonous to plants. When it exists in the soil it is necessary to use
such means of cultivation as shall expose it to the atmosphere and allow
it to take up more oxygen and become the peroxide. The black scales
which fly from hot iron when struck by the blacksmith's hammer are
protoxide of iron.
The _peroxide of iron_ is a very good absorbent of ammonia, and
consequently, as will be hereafter described, adds to the fertility of
the soil.
[What can you say of the oxide of manganese?
How do you classify the inorganic constituents?]
OXIDE OF MANGANESE, though often found in small quantities in the ashes
of cultivated plants, cannot be considered indispensable.
Having now examined all of the materials from which the ashes of plants
are formed,[F] we are enabled to classify them in a simple manner, so
that they may be recollected. They are as follows:--
ALKALIES. ACIDS. NEUTRALS.
Potash. Sulphuric acid. Silica.
Soda. Phosphoric " Chlorine.
Lime. Oxide of Iron.
Magnesia. " Manganese.
FOOTNOTES:
[B] Bromine, iodine, etc., are sometimes detected in particular plants,
but need not occupy the attention of the farmer.
[C] This classification is not strictly scientific, but it is one which
the learner will find it well to adopt. These bodies are called neutrals
because they have no decided alkaline or acid character.
[D] In some soils the _fluorides_ undoubtedly supply plants with soluble
silicates, as _fluoric acid_ has the power of dissolving silica. Thus,
in Derbyshire (England), where the soil is supplied with fluoric acid,
grain is said never to lodge.
[E] Sourness.
[F] There is reason to suppose that _alumina_ is an essential
constituent of many plants.
CHAPTER V.
GROWTH.
[Of what does a perfect young plant consist?
How must the food of plants be supplied?
Can carbon and earthy matter be taken up at separate stages of growth,
or must they both be supplied at once?]
Having examined the materials of which plants are made, it becomes
necessary to discover how they are put together in the process of
growth. Let us therefore suppose a young wheat-plant for instance to be
in condition to commence independent growth.
It consists of roots which are located in the soil; leaves which are
spread in the air, and a stem which connects the roots and leaves. This
stem contains sap vessels (or tubes) which extend from the ends of the
roots to the surfaces of the leaves, thus affording a passage for the
sap, and consequently allowing the matters taken up to be distributed
throughout the plant.
[What seems to be nature's law with regard to this?
What is the similarity between making a cart and raising a crop?
In the growth of a young plant, what operations take place about the
same time?]
It is necessary that the materials of which plants are made should be
supplied in certain proportions, and at the same time. For instance,
carbon could not be taken up in large quantities by the leaves, unless
the roots, at the same time, were receiving from the soil those mineral
matters which are necessary to growth. On the other hand, no
considerable amount of earthy matter could be appropriated by the roots
unless the leaves were obtaining carbon from the air. This same rule
holds true with regard to all of the constituents required; Nature
seeming to have made it a law that if one of the important ingredients
of the plant is absent, the others, though they may be present in
sufficient quantities, cannot be used. Thus, if the soil is deficient in
potash, and still has sufficient quantities of all of the other
ingredients, the plant cannot take up these ingredients, because potash
is necessary to its life.
If a farmer wishes to make a cart he prepares his wood and iron, gets
them all in the proper condition, and then can very readily put them
together. But if he has all of the _wood_ necessary and no _iron_, he
cannot make his cart, because bolts, nails and screws are required, and
their place cannot be supplied by boards. This serves to illustrate the
fact that in raising plants we must give them every thing that they
require, or they will not grow at all.
In the case of our young plant the following operations are going on at
about the same time.
The leaves are absorbing carbonic acid from the atmosphere, and the
roots are drinking in water from the soil.
[What becomes of the carbonic acid?
How is the sap disposed of?
What does it contain?
How does the plant obtain its carbon?
Its oxygen and hydrogen?
Its nitrogen?
Its inorganic matter?]
Under the influence of daylight, the carbonic acid is decomposed; its
oxygen returned to the atmosphere, and its carbon retained in the plant.
The water taken in by the roots circulates through the sap vessels of
the plant, and, from various causes, is drawn up towards the leaves
where it is evaporated. This water contains the _nitrogen_ and the
_inorganic matter_ required by the plant and some carbonic acid, while
the water itself consists of _hydrogen_ and _oxygen_.
Thus we see that the plant obtains its food in the following manner:--
CARBON.--In the form of _carbonic acid_ from the atmosphere, and from
that contained in the sap, the oxygen being returned to the
air.
OXYGEN } From the elements of the water constituting the sap.
& }
HYDROGEN.}
NITROGEN.--From the soil (chiefly in form of ammonia). It is carried
into the plant through the roots in solution in water.
INORGANIC} From the soil, and only _in solution_ in water.
MATTER. }
[What changes does the food taken up by the plant undergo?]
Many of the chemical changes which take place in the interior of the
plant are well understood, but they require too much knowledge of
chemistry to be easily comprehended by the young learner, and it is not
absolutely essential that they should be understood by the scholar who
is merely learning the _elements_ of the science.
It is sufficient to say that the food taken up by the plant undergoes
such changes as are required for its growth; as in animals, where the
food taken into the stomach, is digested, and formed into bone, muscle,
fat, hair, etc., so in the plant the nutritive portions of the sap are
resolved into wood, bark, grain, or some other necessary part.
The results of these changes are of the greatest importance in
agriculture, and no person can call himself a _practical farmer_ who
does not thoroughly understand them.
CHAPTER VI.
PROXIMATE DIVISION OF PLANTS, ETC.
We have hitherto examined what is called the _ultimate_ division of
plants. That is, we have looked at each one of the elements separately,
and considered its use in vegetable growth.
[Of what do wood, starch and the other vegetable compounds
chiefly consist?
Are their small ashy parts important?
What are these compounds called?
Into how many classes may proximate principles be divided?
Of what do the first class consist? The second?
What vegetable compounds do the first class comprise?]
We will now examine another division of plants, called their _proximate
division_. We know that plants consist of various substances, such as
wood, gum, starch, oil, etc., and on examination we shall discover that
these substances are composed of the various _organic_ and _inorganic_
ingredients described in the preceding chapters. They are made up almost
entirely of _organic_ matter, but their ashy parts, though very small,
are (as we shall soon see) sometimes of great importance.
These compounds are called _proximate principles_,[G] or _vegetable
proximates_. They may be divided into two classes.
The first class are composed of _carbon_, _hydrogen_, and _oxygen_.
The second class contain the same substances and _nitrogen_.
[Are these substances of about the same composition?
Can they be artificially changed from one to another?
Give an instance of this.
Is the ease with which these changes take place important?
From what may the first class of proximates be formed?]
The first class (those compounds not containing nitrogen) comprise the
wood, starch, gum, sugar, and fatty matter which constitute the greater
part of all plants, also the acids which are found in sour fruits, etc.
Various as are all of these things in their characters, they are
entirely composed of the same ingredients (carbon, hydrogen and oxygen),
and usually combined in about the _same proportion_. There may be a
slight difference in the composition of their _ashes_, but the organic
part is much the same in every case, so much so, that they can often be
artificially changed from one to the other.
As an instance of this, it may be recollected by those who attended the
Fair of the American Institute, in 1834, that Prof. Mapes exhibited
samples of excellent sugar made from the juice of the cornstalk, starch,
linen, and woody fibre.
The ease with which these proximates may be changed from one to the
other is their most important agricultural feature, and should be
clearly understood before proceeding farther. It is one of the
fundamental principles on which the growth of both vegetables depends.
The proximates of the first class constitute usually the greater part of
all plants, and they are readily formed from the carbonic acid and water
which in nature are so plentifully supplied.
[Why are those of the second class particularly important to
farmers?
What is the general name under which they are known?
What is the protein of wheat called?
Why is flour containing much gluten preferred by bakers?
Can protein be formed without nitrogen?
If plants were allowed to complete their growth without a supply of this
ingredient, what would be the result?]
The _second class_ of proximates, though forming only a small part of
the plant, are of the greatest importance to the farmer, being the ones
from which _animal muscle_[H] is made. They consist, as will be
recollected, of carbon, hydrogen, oxygen and _nitrogen_, or of _all_ of
the organic elements of plants. They are all of much the same character,
though each kind of plant has its peculiar form of this substance, which
is known under the general name of _protein_.
The protein of wheat is called _gluten_--that of Indian corn is
_zein_--that of beans and peas is _legumin_. In other plants the protein
substances are _vegetable albumen_, _casein_, etc.
Gluten absorbs large quantities of water, which causes it to swell to a
great size, and become full of holes. Flour which contains much gluten,
makes light, porous bread, and is preferred by bakers, because it
absorbs so large an amount of water.
[What is the result if a field be deficient in nitrogen?]
The protein substances are necessary to animal and vegetable life, and
none of our cultivated plants will attain maturity (complete their
growth), unless allowed the materials required for forming this
constituent. To furnish this condition is the object of nitrogen given
to plants as manure. If no _nitrogen_ is supplied the protein
substances cannot be formed, and the plant must cease to grow.
When on the contrary _ammonia_ is given to the soil (by rains or
otherwise), it furnishes nitrogen, while the carbonic acid and water
yield the other constituents of protein, and a healthy growth continues,
provided that the soil contains the _mineral_ matters required in the
formation of the ash, in a condition to be useful.
The wisdom of this provision is evident when we recollect that the
protein substances are necessary to the formation of muscle in animals,
for if plants were allowed to complete their growth without a supply of
this ingredient, our grain and hay might not be sufficiently well
supplied with it to keep our oxen and horses in working condition, while
under the existing law plants must be of nearly a uniform quality (in
this respect), and if a field is short of nitrogen, its crop will not be
large, and of a very poor quality, but the soil will produce good plants
as long as the nitrogen lasts, and then the growth must cease.[I]
ANIMALS.
That this principle may be clearly understood, it may be well to explain
more fully the application of the proximate constituents of plants in
feeding animals.
[Of what are the bodies of animals composed?
What is the office of vegetation?
What part of the animal is formed from the first class of proximates?
From the second?
Which contains the largest portions of inorganic matter, plants or
animals?
Must animals have a variety of food, and why?]
Animals are composed (like plants) of organic and inorganic matter, and
every thing necessary to build them up exists in plants. It seems to be
the office of the vegetable world to prepare the gases in the
atmosphere, and the minerals in the earth for the uses of animal life,
and to effect this plants put these gases and minerals together in the
form of the various _proximates_ (or compound substances) which we have
just described.
In animals the compounds containing _no nitrogen_ comprise the fatty
substances, parts of the blood, etc., while the protein compound, or
those which _do contain nitrogen_, form the muscle, a part of the bones,
the hair, and other portions of the animal.
Animals contain a larger proportion of inorganic matter than plants do.
Bones contain a large quantity of phosphate of lime, and we find other
inorganic materials performing important offices in the system.
In order that animals may be perfectly developed, they must of course
receive as food all of the materials required to form their bodies. They
cannot live if fed entirely on one ingredient. Thus, if _starch_ alone
be eaten by the animal, he might become _fat_, but his strength would
soon fail, because his food contains nothing to keep up the vigor of his
_muscles_. If on the contrary the food of an animal consisted entirely
of _gluten_, he might be very strong from a superior development of
muscle, but would not be fat. Hence we see that in order to keep up the
proper proportion of both fat and muscle in our animals (or in
ourselves), the food must be such as contains a proper proportion of the
two kinds of proximates.
[Why is grain good for food?
On what does the value of flour depend?
Is there any relation between the ashy part of plants and those of
animals?
How may we account for unhealthy bones and teeth?]
It is for this reason that grain, such as wheat for instance, is so good
for food. It contains both classes of proximates, and furnishes material
for the formation of both fat and muscle. The value of _flour_ depends
very much on the manner in which it is manufactured. This will be soon
explained.
[What is a probable cause of consumption?
What is an important use of the first class of proximates?
What may lungs be called?
Explain the production of heat during decomposition.
Why is the heat produced by decay not perceptible?]
Apart from the relations between the _proximate principles_ of plants,
and those of animals, there exists an important relation between their
_ashy_ or _inorganic_ parts; and, food in order to satisfy the demands
of animal life, must contain the mineral matter required for the
purposes of that life. Take bones for instance. If phosphate of lime is
not always supplied in sufficient quantities by food, animals are
prevented from the formation of healthy bones. This is particularly to
be noticed in teeth. Where food is deficient of phosphate of lime, we
see poor teeth as a result. Some physicians have supposed that one of
the causes of consumption is the deficiency of phosphate of lime in
food.
[Why is the heat produced by combustion apparent?
Explain the production of heat in the lungs of animals?
Why does exercise augment the animal heat?
Under what circumstances is the animal's own fat used in the production
of heat?]
The first class of proximates (starch, sugar, gum, etc.), perform an
important office in the animal economy aside from their use in making fat.
They constitute the _fuel_ which supplies the animal's fire, and gives him
his _heat_. The lungs of men and other animals may be called delicate
_stoves_, which supply the whole body with heat. But let us explain this
matter more fully. If wood, starch, gum, or sugar, be burned in a stove,
they produce heat. These substances consist, as will be recollected, of
carbon, hydrogen, and oxygen, and when they are destroyed in any way
(provided they be exposed to the atmosphere), the hydrogen and oxygen unite
and form water, and the carbon unites with the oxygen of the air and forms
carbonic acid, as was explained in a preceding chapter. This process is
always accompanied by the liberation of _heat_, and the _intensity_ of this
heat depends on the _time_ occupied in its _production_. In the case of
decay, the chemical changes take place so slowly that the heat, being
conducted away as soon as formed, is not perceptible to our senses. In
combustion (or burning) the same changes take place with much greater
rapidity, and the same _amount_ of heat being concentrated, or brought out
in a far shorter time, it becomes intense, and therefore apparent. In the
lungs of animals the same law holds true. The blood contains matters
belonging to this carbonaceous class, and they undergo in the lungs the
changes which have been described under the head of combustion and decay.
Their hydrogen and oxygen unite, and form the moisture of the breath, while
their carbon is combined with the oxygen of the air drawn into the lungs,
and is thrown out as carbonic acid. The same consequence--heat--results in
this, as in the other cases, and this heat is produced with sufficient
rapidity for the animal necessities. When an animal exercises violently,
his blood circulates with increased rapidity, thus carrying carbon more
rapidly to the lungs. The breath also becomes quicker, thus supplying
increased quantities of oxygen. In this way the decomposition becomes more
rapid, and the animal is heated in proportion.
Thus we see that food has another function besides that of forming
animal matter, namely to supply heat. When the food does not contain a
sufficient quantity of starch, sugar, etc., to answer the demands of
the system the _animal's own fat_ is carried to the lungs, and there
used in the production of heat. This important fact will be referred to
again.
FOOTNOTES:
[G] By _proximate principle_, we mean that combination of vegetable
elements which is known as a vegetable product, such as _wood_, etc.
[H] _Muscle_ is _lean meat_, it gives to animals their strength and
ability to perform labor.
[I] This, of course, supposes that the soil is fertile in other
respects.
CHAPTER VII.
LOCATION OF THE PROXIMATES AND VARIATIONS IN THE ASHES OF PLANTS.
[Of what proximate are plants chiefly composed?
What is the principal constituent of the potato root?
Of the carrot and turnip?
What part of the plant contains usually the most nutriment?]
Let us now examine plants with a view to learning the _location_ of the
various plants.
The stem or trunk of the plant or tree consists almost entirely of
_woody fibre_; this also forms a large portion of the other parts except
the seeds, and, in some instances, the roots. The roots of the potato
contain large quantities of _starch_. Other roots such as the _carrot_
and _turnip_ contain _pectic acid_,[J] a nutritious substance resembling
starch.
It is in the _seed_ however that the more nutritive portions of most
plants exist, and here they maintain certain relative positions which
it is well to understand, and which can be best explained by reference
to the following figures, as described by Prof. Johnston:--
[Illustration: Fig. 1.]
"Thus _a_ shows the position of the oil in the outer part of the
seed--it exists in minute drops, inclosed in six-sided cells, which
consists chiefly of gluten; _b_, the position and comparative quantity
of the starch, which in the heart of the seed is mixed with only a small
proportion of gluten; _c_, the germ or chit which contains much
gluten."[K]
[Is the composition of the inorganic matter of different parts
of the plant the same, or different?
What is the difference between the ash of the straw and that of the
grain of wheat?]
The location of the _inorganic_ part of plants is one of much interest,
and shows the adaptation of each part to its particular use. Take a
wheat plant, for instance--the stalk, the leaf, and the grain, show in
their ashes, important difference of composition. The stalk or straw
contains three or four times as large a proportion of ash as the grain,
and a no less remarkable difference of composition may be noticed in
the ashes of the two parts. In that of the straw, we find a large
proportion of silica and scarcely any phosphoric acid, while in that of
the grain there is scarcely a trace of silica, although phosphoric acid
constitutes more than one half of the entire weight. The leaves contain
a considerable quantity of lime.
[What is the reason for this difference?
In what part of the grain does phosphoric acid exist most largely?]
This may at first seem an unimportant matter, but on examination we
shall see the use of it. The straw is intended to support the grain and
leaves, and to convey the sap from the roots to the upper portions of
the plant. To perform these offices, _strength_ is required, and this is
given by the _silica_, and the woody fibre which forms so large a
proportion of the stalk. The silica is combined with an alkali, and
constitutes the glassy coating of the straw. While the plant is young,
this coating is hardly apparent, but as it grows older, as the grain
becomes heavier, (verging towards ripeness), the silicious coating of
the stalk assumes a more prominent character, and gives to the straw
sufficient strength to support the golden head. The straw is not the
most important part of the plant as _food_, and therefore requires but
little phosphoric acid.
[Why is Graham flour more wholesome than fine flour?
Are the ashes of all plants the same in their composition?]
The grain, on the contrary, is especially intended as food, and
therefore must contain a large proportion of phosphoric acid--this
being, as we have already learned, necessary to the formation of
bone--while, as it has no necessity for strength, and as silica is not
needed by animals, this ingredient exists in the grain only in a very
small proportion. It may be well to observe that the phosphoric acid of
grain exists most largely in the hard portions near the shell, or bran.
This is one of the reasons why Graham flour is more wholesome than fine
flour. It contains all of the nutritive materials which render the grain
valuable as food, while flour which is very finely bolted[L] contains
only a small part of the outer portions of the grain (where the
phosphoric acid, protein and fatty matters exist most largely). The
starchy matter in the interior of the grain, which is the least capable
of giving strength to the animal, is carefully separated, and used as
food for man, while the better portions, not being ground so finely, are
rejected. This one thing alone may be sufficient to account for the
fact, that the lives of men have become shorter and less blessed with
health and strength, than they were in the good old days when a stone
mortar and a coarse sieve made a respectable flour mill.
Another important fact concerning the ashes of plants is the difference
of their composition in different plants. Thus, the most prominent
ingredient in the ash of the potato is _potash_; of wheat and other
grains, _phosphoric acid_; of meadow hay, _silica_; of clover, _lime_;
of beans, _potash_, etc. In grain, _potash_ (or _soda_), etc., are among
the important ingredients.
[Of what advantage are these differences to the farmer?
Of what are plants composed?]
These differences are of great importance to the practical farmer, as by
understanding what kind of plants use the most of one ingredient, and
what kind requires another in large proportion, he can regulate his
crops so as to prevent his soil from being exhausted more in one
ingredient than in the others, and can also manure his land with
reference to the crop which he intends to grow. The tables of analyses
in the fifth section will point out these differences accurately.
FOOTNOTES:
[J] This pectic acid gelatinizes food in the stomach, and thus renders
it more digestible.
[K] See Johnston's Elements, page 41.
[L] Sifted through a fine cloth called a bolting cloth.
CHAPTER VIII.
RECAPITULATION.
We have now learned as much about the plant as is required for our
immediate uses, and we will carefully reconsider the various points with
a view to fixing them permanently in the mind.
Plants are composed of _organic_ and _inorganic_ matter.
[What is organic matter? Inorganic?
Of what does organic matter consist? Inorganic?
How do plants obtain their organic food?
How their inorganic?
How is ammonia supplied? Carbonic acid?]
Organic matter is that which burns away in the fire. Inorganic matter is
the ash left after burning.
The organic matter of plants consists of three gases, oxygen, hydrogen
and nitrogen, and one solid substance carbon (or charcoal). The
inorganic matter of plants consists of potash, soda, lime, magnesia,
sulphuric acid, phosphoric acid, chlorine, silica, oxide of iron, and
oxide of manganese.
Plants obtain their organic food as follows:--Oxygen and hydrogen from
water, nitrogen from some compound containing nitrogen (chiefly from
ammonia), and carbon from the atmosphere where it exists as carbonic
acid--a gas.
They obtain their inorganic food from the soil.
The water which supplies oxygen and hydrogen to plants is readily
obtained without the assistance of manures.
Ammonia is obtained from the atmosphere, by being absorbed by rain and
carried into the soil, and it enters plants through their roots. It may
be artificially supplied in the form of animal manure with profit.
Carbonic acid is absorbed from the atmosphere by leaves, and decomposed
in the green parts of plants under the influence of daylight; the carbon
is retained, and the oxygen is returned to the atmosphere.
[When plants are destroyed by combustion or decay, what
becomes of their constituents?
How does the inorganic matter enter the plant?
Are the alkalies soluble in their pure forms?
Which one of them is injurious when too largely present?
How may sulphuric acid be supplied?
Is phosphoric acid important?
How must silica be treated?
From what source may we obtain chlorine?]
When plants are destroyed by decay, or burning, their organic
constituents pass away as water, ammonia, carbonic acid, etc., ready
again to be taken up by other plants.
The inorganic matters in the soil can enter the plant only when
dissolved in water. _Potash_, _soda_, _lime_, and _magnesia_, are
soluble in their pure forms. Magnesia is injurious when present in too
large quantities.
_Sulphuric_ acid is often necessary as a manure, and is usually most
available in the form of sulphate of lime or plaster. It is also
valuable in its pure form to prevent the escape of ammonia from
composts.
_Phosphoric_ acid is highly important, from its frequent deficiency in
worn-out soils. It is available only under certain conditions which will
be described in the section on manures.
_Silica_ is the base of common sand, and must be united to an alkali
before it can be used by the plant, because it is insoluble except when
so united.
_Chlorine_ is a constituent of common salt (chloride of sodium), and
from this source may be obtained in sufficient quantities for manurial
purposes.
[What is the difference between _per_oxide and _prot_oxide of
iron?
How must the food of plants be supplied?
What takes place after it enters the plant?
What name is given to the compounds thus formed?
How are proximates divided?
Which class constitutes the largest part of the plant?
Of what are animals composed, and how do they obtain the materials from
which to form their growth?]
_Oxide of iron_ is iron rust. There are two oxides of iron, the
_peroxide_ (red) and the _protoxide_ (black). The former is a
fertilizer, and the latter poisons plants.
_Oxide of manganese_ is often absent from the ashes of our cultivated
plants.
The food of plants, both organic and inorganic, must be supplied in
certain proportions, and at the time when it is required. In the plant,
this food undergoes such chemical changes as are necessary to growth.
The compounds formed by these chemical combinations are called
_proximates_.
Proximates are of two classes, those not containing nitrogen, and those
which do contain it.
The first class constitute nearly the whole plant.
The second class, although small in quantity, are of the greatest
importance to the farmer, as from them all animal muscle is made.
Animals, like plants, are composed of both organic and inorganic matter,
and their bodies are obtained directly or indirectly from plants.
[What parts of the animal belong to the first class of
proximates?
What to the second?
What is necessary to the perfect development of animals?
Why are seeds valuable for working animals?
What other important use, in animal economy, have proximates of the
first class?
Under what circumstances is animal fat decomposed?]
The first class of proximates in animals comprise the fat, and like
tissues.
The second class form the muscle, hair, gelatine of the bones, etc.
In order that they may be perfectly developed, animals must eat both
classes of proximates, and in the proportions required by their natures.
They require the phosphate of lime and other inorganic food which exist
in plants.
Seeds are the best adapted to the uses of working animals, because they
are rich in all kinds of food required.
Aside from their use in the formation of _fat_, proximates of the first
class are employed in the lungs, as fuel to keep up animal heat, which
is produced (as in fire and decay) by the decomposition of these
substances.
When the food is insufficient for the purposes of heat, the animal's own
fat is decomposed, and carried to the lungs as fuel.
The stems, roots, branches, etc., of most plants consist principally of
_woody fibre_.
Their seeds, and sometimes their roots, contain considerable quantities
of _starch_.
[Name the parts of the plant in which the different proximates
exist.
State what you know about flour.
Do we know that different plants have ashes of different composition?]
The _protein_ and the _oils_ of most plants exist most largely in the
_seeds_.
The location of the proximates, as well as of the inorganic parts of the
plant, show a remarkable reference to the purposes of growth, and to the
wants of the animal world, as is noticed in the difference between the
construction of the straw and that of the kernel of wheat.
The reason why the fine flour now made is not so healthfully nutritious
as that which contained more of the coarse portions, is that it is
robbed of a large proportion of protein and phosphate of lime, while it
contains an undue amount of starch, which is available only to form fat,
and to supply fuel to the lungs.
Different plants have ashes of different composition. Thus--one may take
from the soil large quantities of potash, another of phosphoric acid,
and another of lime.
By understanding these differences, we shall be able so to regulate our
rotations, that the soil may not be called on to supply more of one
ingredient than of another, and thus it may be kept in balance.
[How are farmers to be benefited by such knowledge?]
The facts contained in this chapter are the _alphabet of agriculture_,
and the learner should not only become perfectly familiar with them, but
should also clearly understand the _reasons_ why they are true, before
proceeding further.
SECTION SECOND.
THE SOIL.
CHAPTER I.
FORMATION AND CHARACTER OF THE SOIL.
[What is a necessary condition of growth?]
In the foregoing section, we have studied the character of plants and
the laws which govern their growth. We learned that one necessary
condition for growth is a fertile soil, and therefore we will examine
the nature of different soils, in order that we may understand the
relations between them and plants.
[What is a fixed character of soils?
How is the chemical character of the soil to be ascertained?
What do we first learn in analyzing a soil?
How do the proportions of organic or inorganic parts of soils compare
with those of plants?
Of what does the organic part of soils consist?]
The soil is not to be regarded as a mysterious mass of dirt, whereon
crops are produced by a mysterious process. Well ascertained scientific
knowledge has proved beyond question that all soils, whether in America
or Asia, whether in Maine or California, have certain fixed properties,
which render them fertile or barren, and the science of agriculture is
able to point out these characteristics in all cases, so that we can
ascertain from a scientific investigation what would be the chances for
success in cultivating any soil which we examine.
The soil is a great chemical compound, and its chemical character is
ascertained (as in the case of plants) by analyzing it, or taking it
apart.
We first learn that fertile soils contain both organic and inorganic
matter; but, unlike the plant, they usually possess much more of the
latter than of the former.
In the plant, the organic matter constitutes the most considerable
portion of the whole. In the soil, on the contrary, it usually exists in
very small quantities, while the inorganic portions constitute nearly
the whole bulk.
[Can the required proportion be definitely indicated?
From what source is the inorganic part of soils derived?
Do all soils decompose with equal facility?
How does frost affect rocks?
Does it affect soils in the same way?]
The organic part of soils consists of the same materials that constitute
the organic part of the plants, and it is in reality decayed vegetable
and animal matter. It is not necessary that this organic part of the
soil should form any particular proportion of the whole, and indeed we
find it varying from one and a half to fifty, and sometimes, in peaty
soils, to over seventy per cent. All fertile soils contain some organic
matter, although it seems to make but little difference in fertility,
whether it be ten or fifty per cent.
The inorganic part of soils is derived from the crumbling of rocks. Some
rocks (such as the slates in Central New York) decompose, and crumble
rapidly on being exposed to the weather; while granite, marble, and
other rocks will last for a long time without perceptible change. The
_causes_ of this crumbling are various, and are not unimportant to the
agriculturist; as by the same processes by which his soil was formed, he
can increase its depth, or otherwise improve it. This being the case, we
will in a few words explain some of the principal pulverizing agents.
1. The action of frost. When water lodges in the crevices of rocks, and
_freezes_, it expands, and bursts the rock, on the same principle as
causes it to break a pitcher in winter. This power is very great, and by
its assistance, large cannon may be burst. Of course the action of frost
is the same on a small scale as when applied to large masses of matter,
and, therefore, we find that when water freezes in the _pores_[M] of
rocks or stones, it separates their particles and causes them to
crumble. The same rule holds true with regard to stiff clay soils. If
they are _ridged_ in autumn, and left with a rough surface exposed to
the frosts of winter, they will become much lighter, and can afterwards
be worked with less difficulty.
[What is the effect of water on certain rocks?
How are some rocks affected by exposure to the atmosphere? Give an
instance of this.]
2. The action of water. Many kinds of rock become so soft on being
soaked with water, that they readily crumble.
3. The chemical changes of the constituents of the rock. Many kinds of
rock are affected by exposure to the atmosphere, in such a manner, that
changes take place in their chemical character, and cause them to fall
to pieces. The red kellis of New Jersey (a species of sandstone), is,
when first quarried, a very hard stone, but on exposure to the
influences of the atmosphere, it becomes so soft that it may be easily
crushed between the thumb and finger.
[What is the similarity between the composition of soils and
the rocks from which they were formed?
What does feldspar rock yield? Talcose slate? Marls?
Does a soil formed entirely from rock contain organic matter?
How is it affected by the growth of plants?]
Other actions, of a less simple kind, exert an influence on the
stubbornness of rocks, and cause them to be resolved into soils.[N] Of
course, the composition of the soil must be similar to that of the rock
from which it was formed; and, consequently, if we know the chemical
character of the rock, we can tell whether the soil formed from it can
be brought under profitable cultivation. Thus feldspar, on being
pulverized, yields potash; talcose slate yields magnesia; marls yield
lime, etc.
The soil formed entirely from rock, contains, of course, no organic
matter.[O] Still it is capable of bearing plants of a certain class, and
when these die, they are deposited in the soil, and thus form its
organic portions, rendering it capable of supporting those plants which
furnish food for animals. Thousands of years must have been occupied in
preparing the earth for habitation by man.
As the inorganic or mineral part of the soil is usually the largest, we
will consider it first.
As we have stated that this portion is formed from rocks, we will
examine their character, with a view to showing the different qualities
of soils.
[What is the general rule concerning the composition of rocks?
Do these distinctions affect the fertility of soils formed from them?
What do we mean by the mechanical character of the soil?
Is its fertility indicated by its mechanical character?]
As a general rule, it may be stated that _all rocks are either
sandstones, limestones, or clays; or a mixture of two or more of these
ingredients_. Hence we find that all mineral soils are either _sandy_,
_calcareous_, (limey), or _clayey_; or consist of a mixture of these, in
which one or another usually predominates. Thus, we speak of a sandy
soil, a clay soil, etc. These distinctions (sandy, clayey, loamy, etc.)
are important in considering the _mechanical_ character of the soil, but
have little reference to its fertility.
By _mechanical_ character, we mean those qualities which affect the ease
of cultivation--excess or deficiency of water, ability to withstand
drought, etc. For instance, a heavy clay soil is difficult to
plow--retains water after rains, and bakes quite hard during drought;
while a light sandy soil is plowed with ease, often allows water to pass
through immediately after rains, and becomes dry and powdery during
drought. Notwithstanding those differences in their mechanical
character, both soils may be very fertile, or one more so than the
other, without reference to the clay and sand which they contain, and
which, to _our observation_, form their leading characteristics. The
same facts exist with regard to a loam, a calcareous (or limey) soil, or
a vegetable mould. Their mechanical texture is not essentially an index
to their fertility, nor to the manures required to enable them to
furnish food to plants. It is true, that each kind of soil appears to
have some general quality of fertility or barrenness which is well known
to practical men, yet this is not founded on the fact that the clay or
the sand, or the vegetable matter, enter more largely into the
constitution of plants than they do when they are not present in so
great quantities, but on certain other facts which will be hereafter
explained.
[What is a sandy soil? A clay soil? A loamy soil? A marl? A
calcareous soil? A peaty soil?]
As the following names are used to denote the character of soils, in
ordinary agricultural description, we will briefly explain their
application:
A _Sandy soil_ is, of course, one in which sand largely predominates.
_Clay soil_, one where _clay_ forms a large proportion of the soil.
_Loamy soil_, where sand and clay are about equally mixed.
_Marl_ contains from five to twenty per cent. of carbonate of lime.
_Calcareous soil_ more than twenty per cent.
_Peaty soils_, of course, contain large quantities of organic matter.[P]
[How large a part of the soil may be used as food by plants?
What do we learn from the analyses of barren and fertile soils?]
We will now take under consideration that part of the soil on which
depends its ability to supply food to the plant. This portion rarely
constitutes more than five or ten per cent. of the entire soil,
sometimes less--and it has no reference to the sand, clay, and vegetable
matters which they contain. From analyses of many fertile soils, and of
others which are barren or of poorer quality, it has been ascertained
that the presence of certain ingredients is necessary to fertility. This
may be better explained by the assistance of the following table:
---------------------------+--------------+-------------+----------
In one hundred pounds. | Soil fertile | Good | Barren.
| without | wheat soil. |
| manure. | |
---------------------------+--------------+-------------+----------
Organic matter, | 9.7 | 7.0 | 4.0
Silica (sand), | 64.8 | 74.3 | 77.8
Alumina (clay), | 5.7 | 5.5 | 9.1
Lime, | 5.9 | 1.4 | .4
Magnesia, | .9 | .7 | .1
Oxide of iron, | 6.1 | 4.7 | 8.1
Oxide of manganese, | .1 | | .1
Potash, | .2 | 1.7 |
Soda, | .4 | .7 |
Chlorine, | .2 | .1 |
Sulphuric acid, | .2 | .1 |
Phosphoric acid, | .4 | .1-1/2 |
Carbonic acid, | 4.0 | |
Loss during the analysis | 1.4 | 3.6-1/2 | .4
+--------------+-------------+----------
|100.0 |100.0 |100.0
---------------------------+--------------+-------------+----------
[What can you say of the soils represented in the table of
analyses?
What proportion of the fertilizing ingredients is required?
If the soil represented in the third column contained all the
ingredients required except potash and soda, would it be fertile?
What would be necessary to make it so?
What is the reason for this?
What are the offices performed by the inorganic part of soils?]
The soil represented in the first column might still be fertile with
less organic matter, or with a larger proportion of clay (alumina), and
less sand (silica). These affect its _mechanical_ character; but, if we
look down the column, we notice that there are small quantities of lime,
magnesia, and the other constituents of the ashes of plants (except ox.
of manganese). It is not necessary that they should be present in the
soil in the exact quantity named above, but _not one must be entirely
absent, or greatly reduced in proportion_. By referring to the third
column, we see that these ingredients are not all present, and the soil
is barren. Even if it were supplied with all but one or two, potash and
soda for instance, it could not support a crop without the assistance of
manures containing these alkalies. The reason for this must be readily
seen, as we have learned that no plant can arrive at maturity without
the necessary supply of materials required in the formation of the ash,
and these materials can be obtained only from the soil; consequently,
when they do not exist there, it must be barren.
The inorganic part of soils has two distinct offices to perform. The
clay and sand form a mass of material into which roots can penetrate,
and thus plants are supported in their position. These parts also absorb
heat, air and moisture to serve the purposes of growth, as we shall see
in a future chapter. The minute portions of soil, which comprise the
acids, alkalies, and neutrals, furnish plants with their ashes, and are
the most necessary to the fertility of the soil.
GEOLOGY.
[What is geology?
Is the same kind of rock always of the same composition?
How do rocks differ?]
The relation between the inorganic part of soils and the rocks from
which it was formed, is the foundation of Agricultural Geology. Geology
may be briefly named the _science of rocks_. It would not be proper in
an elementary work to introduce much of this study, and we will
therefore simply state that the same kind of rock is of the same
composition all over the world; consequently, if we find a soil in New
England formed from any particular rock, and a soil from the same rock
in Asia, their natural fertility will be the same in both localities.
Some rocks consist of a mixture of different kinds of minerals; and
some, consisting chiefly of one ingredient, are of different degrees of
_hardness_. Both of these changes must affect the character of the soil,
but it may be laid down as rule that, _when the rocks of two locations
are exactly alike, the soils formed from them will be of the same
natural fertility, and in proportion as the character of rocks changes,
in the same proportion will the soils differ_.
[What rule may be given in relation to soils formed from the
same or different rocks?
Are all soils formed from the rocks on which they lie?
What instances can you give of this?]
In most districts the soil is formed from the rock on which it lies; but
this is not always the case. Soils are often formed by deposits of
matter brought by water from other localities. Thus the alluvial banks
of rivers consist of matters brought from the country through which the
rivers have passed. The river Nile, in Egypt, yearly overflows its
banks, and deposits large quantities of mud brought from the uninhabited
upper countries. The prairies of the West owe a portion of their soil to
deposits by water. Swamps often receive the washings of adjacent hills;
and, in these cases, their soil is derived from a foreign source.
We might continue to enumerate instances of the relations between soils
and the sources whence they originated, thus demonstrating more fully
the importance of geology to the farmer; but it would be beyond the
scope of this work, and should be investigated by scholars more advanced
than those who are studying merely the _elements_ of agricultural
science.
The mind, in its early application to any branch of study, should not
be charged with intricate subjects. It should master well the
_rudiments_, before investigating those matters which should _follow_
such understanding.
[In what light will plants and soils be regarded by those who
understand them?]
By pursuing the proper course, it is easy to learn all that is necessary
to form a good foundation for a thorough acquaintance with the subject.
If this foundation is laid thoroughly, the learner will regard plants
and soils as old acquaintances, with whose formation and properties he
is as familiar as with the construction of a building or simple machine.
A simple spear of grass will become an object of interest, forming
itself into a perfect plant, with full development of roots, stem,
leaves, and seeds, by processes with which he feels acquainted. The soil
will cease to be mere dirt; it will be viewed as a compound substance,
whose composition is a matter of interest, and whose care is productive
of intellectual pleasure. The commencement of study in any science must
necessarily be wearisome to the young mind, but its more advanced stages
amply repay the trouble of early exertions.
FOOTNOTES:
[M] The spaces between the particles.
[N] In very many instances the crevices and seams of rocks are permeated
by roots, which, by decaying and thus inducing the growth of other
roots, cause these crevices to become filled with organic matter. This,
by the absorption of moisture, may expand with sufficient power to burst
the rock.
[O] Some rocks contain sulphur, phosphorus, etc., and these may,
perhaps, be considered as organic matter.
[P] These distinctions are not essential to be learned, but are often
convenient.
CHAPTER II.
USES OF ORGANIC MATTER.
[What proportion of organic matter is required for fertility?
How does the soil obtain its organic matter?
How does the growth of clover, etc., affect the soil?]
It will be recollected that, in addition to its mineral portions, the
soil contains organic matter in varied quantities. It may be fertile
with but one and a half per cent. of organic matter, and some peaty
soils contain more than fifty per cent. or more than one half of the
whole.
The precise amount necessary cannot be fixed at any particular sum;
perhaps five parts in a hundred would be as good a quantity as could be
recommended.
The soil obtains its organic matter in two ways. First, by the decay of
roots and dead plants, also of leaves, which have been brought to it by
wind, etc. Second, by the application of organic manures.
[When organic matter decays in the soil, what becomes of it?
Is charcoal taken up by plants?
Are humus and humic acid of great practical importance?]
When a crop of clover is raised, it obtains its carbon from the
atmosphere; and, if it be plowed under, and allowed to decay, a portion
of this carbon is deposited in the soil. Carbon constitutes nearly the
whole of the dry weight of the clover, aside from the constituents of
water; and, when we calculate the immense quantity of hay, and roots
grown on an acre of soil in a single season, we shall find that the
amount of carbon thus deposited is immense. If the clover had been
removed, and the roots only left to decay, the amount of carbon
deposited would still have been very great. The same is true in all
cases where the crop is removed, and the roots remain to form the
organic or vegetable part of the soil. While undergoing decomposition, a
portion of this matter escapes in the form of gas, and the remainder
chiefly assumes the form of carbon (or charcoal), in which form it will
always remain, without loss, unless driven out by fire. If a bushel of
charcoal be mixed with the soil now, it will be the same bushel of
charcoal, neither more nor less, a thousand years hence, unless some
influence is brought to bear on it aside from the growth of plants. It
is true that, in the case of the decomposition of organic matter in the
soil, certain compounds are formed, known under the general names of
_humus_ and _humic acid_, which may, in a slight degree, affect the
growth of plants, but their practical importance is of too doubtful a
character to justify us in considering them. The application of manures,
containing organic matter, such as peat, muck, animal manure, etc.,
supplies the soil with carbon on the same principle, and the decomposing
matters also generate[Q] carbonic acid gas while being decomposed. The
agricultural value of carbon in the soil depends (as we have stated),
not on the fact that it enters into the composition of plants, but on
certain other important offices which it performs, as follows:--
[On what does the agricultural value of the carbon in the soil
depend?
Why does it make the soil more retentive of manure?
What is the experiment with the barrels of sand?]
1. It makes the soil more retentive of manures.
2. It causes it to appropriate larger quantities of the fertilizing
gases of the atmosphere.
3. It gives it greater power to absorb moisture.
4. It renders it warmer.
1. Carbon (or charcoal) makes the soil retentive of manures, because it
has in itself a strong power to absorb, and retain[R] fertilizing
matters. There is a simple experiment by which this power can be shown.
Ex.--Take two barrels of pure beach sand, and mix with the sand in one
barrel a few handfuls of charcoal dust, leaving that in the other pure.
Pour the brown liquor of the barn-yard through the pure sand, and it
will pass out at the bottom unaltered. Pour the same liquor through the
barrel, containing the charcoal, and pure water will be obtained as a
result. The reason for this is that the charcoal retains all of the
impurities of the liquor, and allows only the water to pass through.
Charcoal is often employed to purify water for drinking, or for
manufacturing purposes.
[Will charcoal purify water?
If a piece of tainted meat, or a fishy duck be buried in a rich garden
soil, what takes place?
What is the reason of this?
How does charcoal overcome offensive odors?
How can you prove that charcoal absorbs the _mineral_ impurities of
water?]
A rich garden-soil contains large quantities of carbonaceous matter;
and, if we bury in such a soil a piece of tainted meat or a fishy duck,
it will, in a short time, be deprived of its odor, because the charcoal
in the soil will entirely absorb it.
Carbon absorbs gases as well as the impurities of water; and, if a
little charcoal be sprinkled over manure, or any other substance,
emitting offensive odors, the gases escaping will be taken up by the
charcoal, and the odor will cease.
It has also the power of absorbing _mineral_ matters, which are
contained in water. If a quantity of salt water be filtered through
charcoal, the salt will be retained, and the water will pass through
pure.
We are now able to see how carbon renders the soil retentive of manures.
1st. Manures, which resemble the brown liquor of barn-yards, have their
fertilizing matters taken out, and retained by it.
[How does charcoal in the soil affect the manures applied?
Why does charcoal in the soil cause it to appropriate the gases of the
atmosphere?
What fertilizing gases exist in the atmosphere?
How are they carried to the soil?
Does the carbon retain them after they reach the soil?
What can you say of the air circulating through the soil?
How does carbon give the soil power to absorb moisture?]
2d. The gases arising from the decomposition (_rotting_) of manure are
absorbed by it.
3d. The soluble mineral portions of manure, which might in some soils
leach down with water, are arrested and retained at a point at which
they can be made use of by the roots of plants.
2. Charcoal in the soil causes it to appropriate larger quantities of
the fertilizing gases of the atmosphere, on account of its power, as
just named, to absorb gases.
The atmosphere contains results, which have been produced by the
breathing of animals and by the decomposition of various kinds of
organic matter, which are exposed to atmospheric influences. These gases
are chiefly ammonia and carbonic acid, both of which are largely
absorbed by water, and consequently are contained in rain, snow, etc.,
which, as they enter the soil, give up these gases to the charcoal, and
they there remain until required by plants. Even the air itself, in
circulating through the soil, gives up fertilizing gases to the carbon,
which it may contain.
3. Charcoal gives to the soil power to absorb moisture, because it is
itself one of the best absorbents in nature; and it has been proved by
accurate experiment that peaty soils absorb moisture with greater
rapidity, and part with it more slowly than any other kind.
[How does it render it warmer?
Is the heat produced by the decomposition of organic matter perceptible
to our senses?
Is it so to the growing plant?
What is another important part of the organic matter in the soil?]
4. Carbon in the soil renders it warmer, because it darkens its color.
Black surfaces absorb more heat than light ones, and a black coat, when
worn in the sun, is warmer than one of a lighter color. By mixing carbon
with the soil, we darken its color, and render it capable of absorbing a
greater amount of heat from the sun's rays.
It will be recollected that, when vegetable matter decomposes in the
soil, it produces certain gases (carbonic acid, etc.), which either
escape into the atmosphere, or are retained in the soil for the use of
plants. The production of these gases is always accompanied by _heat_,
which, though scarcely perceptible to our senses, is perfectly so to the
growing plant, and is of much practical importance. This will be
examined more fully in speaking of manures.
[How is it obtained by the soil?
What offices does the organic matter in the soil perform?]
Another important part of the organic matter in the soil is that which
contains _nitrogen_. This forms but a very small portion of the soil,
but it is of the greatest importance to vegetables. As the nitrogen in
food is of absolute necessity to the growth of animals, so the nitrogen
in the soil is indispensable to the growth of cultivated plants. It is
obtained by the soil in the form of ammonia (or nitric acid), from the
atmosphere, or by the application of animal matter. In some cases,
manures called _nitrates_[S] are used; and, in this manner, nitrogen is
given to the soil.
We have now learned that the organic matter in the soil performs the
following offices:--
Organic matter thoroughly decomposed is _carbon_, and has the various
effects ascribed to this substance on p. 79.
Organic matter in process of decay produces carbonic acid, and sometimes
ammonia in the soil; also its decay causes heat.
Organic matter containing _nitrogen_, such as animal substances, etc.,
furnish ammonia, and other nitrogenous substances to the roots of
plants.
FOOTNOTES:
[Q] Produce.
[R] By absorbing and retaining, we mean taking up and holding.
[S] Nitrates are compounds of nitric acid (which consists of nitrogen
and oxygen), and alkaline substances. Thus nitrate of potash
(saltpetre), is composed of nitric acid and potash: nitrate of soda
(cubical nitre), of nitric acid and soda.
CHAPTER III.
USES OF INORGANIC MATTER.
[What effect has clay besides the one already named?
How does it compare with charcoal for this purpose?]
The offices performed by the inorganic constituents of the soil are many
and important.
These, as well as the different conditions in which the bodies exist,
are necessary to be thoroughly studied.
Those parts which constitute the larger proportion of the soil, namely
the clay, sand, and limy portions, are useful for purposes which have
been named in the first part of this section, while the _clay_ has an
additional effect in the absorption of ammonia.
For this purpose, it is as effectual as charcoal, the gases escaping
from manures, as well as those existing in the atmosphere, and in
rain-water, being arrested by clay as well as charcoal.[T]
[What particular condition of inorganic matter is requisite
for fertility?
What is the fixed rule with regard to this?
What is the condition of the alkalies in most of their combinations? Of
the acids?
What is said of phosphate of lime?]
The more minute ingredients of the soil--those which enter into the
construction of plants--exist in conditions which are more or less
favorable or injurious to vegetable growth. The principal condition
necessary to fertility is _capacity to be dissolved_, it being (so far
as we have been able to ascertain) a fixed rule, as was stated in the
first section, that _no mineral substance can enter into the roots of a
plant except it be dissolved in water_.
The _alkalies_ potash, soda, lime, and magnesia, are in nearly all of
their combinations in the soil sufficiently soluble for the purposes of
growth.
The _acids_ are, as will be recollected, sulphuric and phosphoric. These
exist in the soil in combination with the alkalies, as sulphates and
phosphates, which are more or less soluble under natural circumstances.
Phosphoric acid in combination with lime as phosphate of lime is but
slightly soluble; but, when it exists in the compound known as
_super_-phosphate of lime, it is much more soluble, and consequently
enters into the composition of plants with much greater facility. This
matter will be more fully explained in the section on manures.
[How may silica be rendered soluble?
What is the condition of chlorine in the soil?
Do peroxide and protoxide of iron affect plants in the same way?
How would you treat a soil containing protoxide of iron?
On what does the usefulness of all these matters in the soil depend?]
The _neutrals_, silica, chlorine, oxide of iron, and oxide of manganese,
deserve a careful examination. Silica exists in the soil usually in the
form of _sand,_ in which it is, as is well known, perfectly insoluble;
and, before it can be used by plants, which often require it in large
quantities, it must be made soluble, which is done by combining it with
an alkali.
For instance, if the silica in the soil is insoluble, we must make an
application of an alkali, such as potash, which will unite with the
silica, and form the silicate of potash, which is in the exact condition
to be dissolved and carried into the roots of plants.
Chlorine in the soil is probably always in an available condition.
Oxide of iron exists, as has been previously stated, usually in the form
of the _per_oxide (or red oxide). Sometimes, however, it exists in the
form of the _prot_oxide (or black oxide), which is poisonous to plants,
and renders the soil unfertile. By loosening the soil in such a manner
as to admit air and water, this compound takes up more oxygen, which
renders it a peroxide, and makes it available for plants. The oxide of
manganese is probably of little consequence.
The usefulness of all of these matters in the soil depends on their
_exposure_; if they are in the _interior_ of particles, they cannot be
made use of; while, if the particles are so pulverized that their
constituents are exposed, they become available, because water can
immediately attack to dissolve, and carry them into roots.
[What is one of the chief offices of plowing and hoeing?
Is the subsoil usually different from the surface soil?
What circumstances have occasioned the difference? In what way?]
This is one of the great offices of plowing and hoeing; the _lumps_ of
soil being thereby more broken up and exposed to the action of
atmospheric influences, which are often necessary to produce a fertile
condition of soil, while the trituration of particles reduces them in
size.
SUBSOIL.
[May the subsoil be made to resemble the surface soil?
May all soils be brought to the highest state of fertility?
On what examination must improvement be based?
What is the difference between the soil of some parts of Massachusetts
and that of the Miami valley?]
The subsoil is usually of a different character from the surface soil,
but this difference is more often the result of circumstances than of
formation. The surface soil from having been long cultivated has been
more opened to the influences of the air than is the case with the
subsoil, which has never been disturbed so as to allow the same action.
Again the growth of plants has supplied the surface soil with roots,
which by decaying have given it organic matter, thus darkening its
color, rendering it warmer, and giving greater ability to absorb heat
and moisture, and to retain manures. All of these effects render the
surface soil of a more fertile character than it was before vegetable
growth commenced; and, where frequent cultivation and manures have been
applied, a still greater benefit has resulted. In most instances the
subsoil may by the same means be gradually improved in condition until
it equals the surface soil in fertility. The means of producing this
result, also farther accounts of its advantages, will be given under the
head of _Cultivation_ (Sect. IV.)
IMPROVEMENT.
From what has now been said of the character of the soil, it must be
evident that, as we know the _causes_ of fertility and barrenness, we
may by the proper means improve the character of all soils which are not
now in the highest state of fertility.
Chemical analysis will tell us the _composition_ of a soil, and an
examination, such as any farmer may make, will inform us of its
deficiencies in _mechanical_ character, and we may at once resort to the
proper means to secure fertility. In some instances the soil may contain
every thing that is required, but not in the necessary condition. For
instance, in some parts of Massachusetts, there are nearly _barren_
soils which show by analysis precisely the same chemical composition as
the soil of the Miami valley of Ohio, one of the most _fertile_ in the
world. The cause of this great difference in their agricultural
capabilities, is that the Miami soil has its particles finely
pulverized; while in the Massachusetts soil the ingredients are combined
within particles (such as pebbles, etc.), where they are out of the
reach of roots.
[Why do soils of the same degree of fineness sometimes differ
in fertility?
Can soils always be rendered fertile with profit?
Can we determine the cost before commencing the work?
What must be done before a soil can be cultivated understandingly?
What must be done to keep up the quality of the soil?]
In other cases, we find two soils, which are equally well pulverized,
and which appear to be of the same character, having very different
power to support crops. Chemical analysis will show in these instances a
difference of composition.
All of these differences may be overcome by the use of the proper means.
Sometimes it could be done at an expense which would be justified by the
result; and, at others, it might require too large an outlay to be
profitable. It becomes a question of economy, not of ability, and
science is able to estimate the cost.
Soil cannot be cultivated understandingly until it has been subjected to
such an examination as will tell us exactly what is necessary to render
it fertile. Even after fertility is perfectly restored it requires
thought and care to maintain it. The ingredients of the soil must be
returned in the form of manures as largely as they are removed by the
crop, or the supply will eventually become too small for the purposes of
vegetation.
FOOTNOTES:
[T] It is due to our country, as well as to Prof. Mapes and others, who
long ago explained this absorptive power of clay and carbon, to say that
the subject was perfectly understood and practically applied in America
a number of years before Prof. Way published the discovery in England as
original.
SECTION THIRD.
MANURES.
CHAPTER I.
CHARACTER AND VARIETIES OF MANURES.
[What must a farmer know in order to avoid failures?
Can this be learned entirely from observation?
What kind of action have manures?
Give examples of each of these.
May mechanical effects be produced by chemical action?
How does potash affect the soil?]
To understand the science of _manures_ is the most important branch of
practical farming. No baker would be called a good practical baker who
kept his flour exposed to the sun and rain. No shoemaker would be called
a good practical shoemaker, who used morocco for the soles of his shoes,
and heavy leather for the uppers. No carpenter would be called a good
practical carpenter, who tried to build a house without nails, or other
fastenings. So with the farmer. He cannot be called a good practical
farmer if he keeps the materials, from which he is to make plants, in
such a condition, that they will have their value destroyed, uses them
in the wrong places, or tries to put them together without having every
thing present that is necessary. Before he can avoid failures _with
certainty_, he must know what manures are composed of, how they are to
be preserved, where they are needed, and what kinds are required. True,
he may from observation and experience, _guess_ at results, but he
cannot _know_ that he is right until he has learned the facts above
named. In this section of our work, we mean to convey some of the
information necessary to this branch of _practical farming_.
We shall adopt a classification of the subject somewhat different from
that found in most works on manures, but the _facts_ are the same. The
action of manures is either _mechanical_ or _chemical_, or a combination
of both. For instance: some kinds of manure improve the mechanical
character of the soil, such as those which loosen stiff clay soils, or
others which render light sandy soils compact--these are called
_mechanical_ manures. Some again furnish food for plants--these are
called _chemical_ manures.
Many mechanical manures produce their effects by means of chemical
action. Thus _potash_ combines chemically with sand in the soil. In so
doing, it roughens the surfaces of the particles of sand, and renders
the soil less liable to be compacted by rains. In this manner, it acts
as a _mechanical_ manure. The compound of sand and potash,[U] as well as
the potash alone, may enter into the composition of plants, and hence it
is a _chemical_ manure. In other words, potash belongs to both classes
described above.
It is important that this distinction should be well understood by the
learner, as the words "mechanical" and "chemical" in connection with
manures will be made use of throughout the following pages.
[What are absorbents?
What kind of manure is charcoal?]
There is another class of manures which we shall call _absorbents_.
These comprise those substances which have the power of taking up
fertilizing matters, and retaining them for the use of plants. For
instance, _charcoal_ is an absorbent. As was stated in the section on
soils, this substance is a retainer of all fertilizing gases and many
minerals. Other matters made use of in agriculture have the same effect.
These absorbents will be spoken of more fully in their proper places.
TABLE.
MECHANICAL MANURES are those which improve the mechanical condition of
soils.
CHEMICAL " are those which serve as food for plants.
ABSORBENTS are those substances which absorb and retain
fertilizing matters.
[Into what classes may manures be divided?
What are organic manures?
Inorganic? Atmospheric?]
Manures may be divided into three classes, viz.: _organic_, _inorganic_,
and _atmospheric_.
ORGANIC manures comprise all _animal_ and _vegetable_ matters which are
used to fertilize the soil, such as dung, muck, etc.
INORGANIC manures are those which are of a purely _mineral_ character,
such as lime, ashes, etc.
ATMOSPHERIC manures consist of those organic manures which are in the
form of gases in the atmosphere, and which are absorbed by rains and
carried to the soil. These are of immense importance. The ammonia and
carbonic acid in the air are atmospheric manures.
FOOTNOTES:
[U] Silicate of potash.