MORTON'S H//VD BOOKS of ^

N2I.

CHEMISTRY

OF THE p/\

BY

R.WARINGTON.F.R.S

SIXTH EDITION

REVISED AND ENLARGED

VINTON & Co. LTD. 9, NEW BRIDGE STREET.

LONDON

MORTON'S HANDBOOKS OF THE FARM,

NO. I.

THE

CHEMISTRY OF THE FARM.

BY

E. WAEINGTON, F.R.S.

SIXTH EDITION.
REVISED AND ENLARGED.

LONDON :
ViNTON & CO., LTD., 9, NEW BRIDGE STREET, E.G.

THE present volume is one of a series discussing the Cul-
tivation of the Farm, its Live Stock, and its Cultivated
Plants, Farm and Estate Equipment, Dairying, and Farm
Labour, the Chemistry of Agriculture, and the Processes of
Animal and Vegetable Life. Among the writers who have
been engaged on them are Messrs. T. BOWICK, the late W.
BUENESS, G. MURRAY, the late W. T. CARRINGTON, the Rev.
G. GILBERT, Messrs. JAMES LONG, J. HILL, SANDERS SPENCER,
and the late J. C. MORTON, Professors G. T. BROWN, J
WORTLEY-AXE, and J. SCOTT, the late Professor JAMES
BUCKMAN, Dr. MAXWELL, T. MASTERS, F.R.S., and Mr. R.
WARINGTON, F.R.S.

PREFACE

TO THE SIXTH EDITION.

As about 27,000 copies of this little book have been
printed during the last ten years in England, the United
States, and Belgium, I am encouraged once more to do
my best to improve it, and to make such alterations and
additions as the progress of Agricultural Chemistry seems
to demand.

The largest additions will be found in the chapters
relating to Manure, Animal Nutrition, Food, and the Dairy.
The new theory of the partial nutrition of leguminous
plants through their root tubercles has been adopted. The
isodynamic values now ascertained for the various con-
stituents of foods have also been introduced ; and for the
first time the comparative value of different foods, and the
ratio of the albuminoid to the non-albuminoid matter in
each food, have been calculated on the basis of these values.
The general aim of the book is, as before, to supply
students with a concise Handbook of Agricultural
Chemistry, describing the more important facts of the
science, and especially those having a practical bearing
on agricultural operations. To teach chemistry, or the
operations of practical agriculture, is not attempted.

R. W.
February, 1891.

CONTENTS.

CHAP. PAGE

I.— PLANT GROWTH 1

II.— THE ATMOSPHERE AND SOIL 16

III.— MANURES 30

IV.— CROPS 47

V.— ROTATION OF CROPS 63

VI.— ANIMAL NUTRITION 75

VII.— FOODS 87

VIII.— RELATION OF FOOD TO ANIMAL REQUIREMENTS . 116

IX.— RELVTION OF FOOD TO MANURE 133

X.— THE DAIRY 143

THE

CHEMISTEY OF THE FABM.

CHAPTER I.

PLANT GROWTH.

The Constituents of Plants. — Water — The combustible elements of vege-
table matter — The proportion of ash constituents in various parts of
plants — The essential and non-essential elements of the ash — Com-
position of a crop of grass. Function of the Leaves. — Assimilation
of carbon from the air — Formation of vegetable substance — Plant
respiration — The transpiration of watef. Function of the Roots. —
Absorption of ash constituents from the soil — The selective power
of plants — Absorption of nitrogenous matter — Cases of union of root
with other organisms. Destination of Ash Constituents. — The
excretion of useless matter by plants— The distribution and
action of ash constituents in the plant. Germination — Gen-
eral character of seeds — The conditions and processes of their
germination. Plant Development. — Annual plants — The order in
which plant constituents are assimilated — Exhaustion of roots and
stem during formation of seed — Biennial and perennial plants — The
storing up of food for a second season — Spring sap rich in sugar.

THE first step towards a knowledge of plant chemistry
must be an acquaintance with the materials of which
plants are built up.

The Constituents of Plants.— The most abundant
ingredient of a living plant is ivater. Many succulent
vegetables, as turnips and lettuce, contain more than 90
per cent, of water. Timber felled in the driest time
seldom contains less than 40 per cent, of water.

2 THE CHEMISTRY OF THE FARM.

If a branch of a tree is burnt, the greater part is con-
sumed and passes away in the form of gas, but there is
left behind a small quantity of white ash. The same
happens if any other part of a plant is burnt. The con-
stituents which form the dry matter of plants may be thus
conveniently divided into two classes — the combustible,
and the incombustible.

The combustible part of plants is made up of five
chemical elements — carbon, oxygen, hydrogen, nitrogen
and sulphur; without these no plant is ever produced.
Carbon generally forms about one-half of the dry com-
bustible matter of plants. Nitrogen seldom exceeds 4 per
cent, of the dry matter, and is generally present in much
smaller amount. Sulphur is still smaller in quantity. The
remainder is oxygen and hydrogen.

The carbon, hydrogen, and oxygen form the cellulose,
lignin, pectin, gummy matters, starch, dextrin, sugar, fat,
and vegetable acids which plants contain. The same ele-
ments united with nitrogen form the amides and alkaloids ;
and further united with sulphur the still more important
albuminoids, which are essential constituents of all plants.

The incombustible, cr ash constituents, form generally
but a small part of the plant. The timber of freely-
growing trees contains but 0*2 — 0*4 of ash constituents in
100 of dry matter. In seeds free from husk the ash is
generally 2 — 5 per cent, of the dry matter. In the straw
of cereals 4 — 7 per cent. In roots and tubers 4 — 8 per cent.
In hay 5 — 9 per cent. It is in leaves, and especially old
leaves, that the greatest proportion of ash is found ; in the
leaves of root crops the ash will amount to 10 — 25 per cent,
of the dry matter.

The incombustible ash always contains five chemical

PLANT CONSTITUENTS. 6

elements — potassium, magnesium, calcium, iron, and phos-
phorus, besides sulphur already mentioned. Iron is present
in only very small quantity. These five elements, though
forming a very small portion of the plant, are indispensable
to its life. Besides the elements just named, an ash will
generally contain sodium, silicon, and chlorine, with fre-
quently manganese, and perhaps minute quantities of
other elements. The supplementary elements just named
are not apparently essential to plant life, though some of
them discharge useful functions in the plant.

The metals above-named occur in the plant as salts,
being combined with phosphoric, nitric, sulphuric, and
various vegetable acids, of which formic, acetic, oxalic,
malic, tartaric, and citric acid are the most common.
The metals are also frequently present as chlorides.
Phosphorus occurs in the form of phosphates ; silicon is
present as silica. Sulphur occurs partly as sulphates,
and partly as a constituent of albuminoids. In the ash
of plants the bases of the nitrates, and of the salts of
vegetable acids, are found in the form of carbonates.

It is usual to speak of the combustible ingredients
of a plant as organic, and of the incombustible ingredients
as inorganic. This distinction is scarcely accurate, as
those ash constituents which are indispensable parts of
plants have, during the life of the plant, as much right to
be called " organic " as albumin or cellulose.

In the following table will be found the average com-
position of a crop of meadow grass weighing five tons when
cut, and producing one and a-half ton of hay ; this will
illustrate what has just been said as to the constituents of
plants. Further information as to the composition of
crops will be found on pp. 48 — 49.

THE CHEMISTRY OP THE FARM.

COMPOSITION OF A CROP OF MEADOW GRASS.

Water . . 8 :-<78 lh«

Carbon
Hydrogen .
Nitrogen .
Oxygen and Sulphur
Potash

1315 j
49 I Combustible matter . 2,613 Ibs.
1105 1

no -s S

Soda ....

11-9
28-1
10-1
•9
12-7
10-8
16-2
57-5
4-5 ,

>Ash . 209 Ibs.

Lime
Magnesia .
Oxide of iron
Phosphoric acid
Sulphuric acid
Chlorine .
Silica
Sand, &c. .

Total crop

11,200 Ibs.

Plants obtain the elements of which they are built up
partly from the soil, and partly from the atmosphere.
From the soil they obtain, by means of their roots, all
their ash constituents, all their sulphur, and nearly the
whole of their nitrogen and water. From the atmosphere
they obtain, through the instrumentality of their leaves,
the whole, or nearly the whole, of their carbon, with pro-
bably small quantities of nitrogen and water.

Function of the Leaves. — 1. Assimilation. — The
source of vegetable carbon is the carbonic acid gas
present in the atmosphere. Carbonic acid and the other
gases of the atmosphere pass through the cuticle of the
plant, and are dissolved by the cell sap : carbonic acid
is much more soluble in water than the nitrogen and
oxygen which make up the bulk of the atmosphere.
The dissolved carbonic acid is decomposed within the
chlorophyll cells of the plant under the influence of
light, oxygen being evolved, and the carbon retained

FUNCTION OF LEAVES. 5

by the plant. The carbonic acid being thus removed
from the cell sap, it becomes capable of dissolving a
fresh supply. All green parts of a plant share in this
power of decomposing carbonic acid, but it is pre-
eminently the function of the leaves. The decom-
position of carbonic acid does not proceed in darkness, or
at a very low temperature. The rays of light most active
in effecting the decomposition are the orange-red rays ;
the green, violet, and dark red rays of the spectrum
have scarcely any influence. The rays of light absorbed
by chlorophyll are, in fact, the ones which accomplish the
chemical work.

The decomposition of carbonic acid by green plants
during daylight is of the utmost importance in maintaining
an atmosphere suitable for the respiration of animals. An
animal in breathing inspires atmospheric air ; it expires
air in which a part of the oxygen has been replaced by
carbonic acid; the result of animal life is thus to accumu-
late carbonic acid in the atmosphere. Such accumulation
would be injurious to the health of animals, but is pre-
vented by the growth of plants. It has been calculated
that an acre of forest, producing annually 5755 Ibs. of
dry matter, will consume the carbonic acid produced by
the respiration of 15'4 men.

Besides carbonic acid, plants are apparently capable
of absorbing a small quantity of ammonia through their
leaves. The uncombined nitrogen of the atmosphere is
not appropriated by the leaves of green plants. When
rain occurs after severe drought, water may be taken up
to some extent through the leaf.

Plants which have no chlorophyll cells, and possess
consequently no green colour, do not decompose carbonic

0 TEE CHEMISTRY OF THE FARM.

acid. We have familiar examples of such plants in the
broomrape and dodder of our clover fields, and in the
common fungi. The broomrape and dodder are fed by
the juices of the plants on which they live as parasites.
The fungi derive their carbon from the decayed vegetable
matter in the soil.

2. Formation of Organic Matter. — The oxygen gas
given off by a green plant exposed to light is so nearly
equal in volume to the carbonic acid decomposed, that
apparently the whole of the oxygen contained in the
carbonic acid is returned to the atmosphere; the reac-
tion is, however, really more complicated, as water is
probably decomposed at the same time as the carbonic
acid.

The exact nature of the reaction which takes place
when carbonic acid is decomposed in the chlorophyll cells
is still unknown. It is probable that formaldehyde is first
produced, according to the following equation :
C02+H20=CH20 + 02.

From formaldehyde glucose is possibly derived by a
process of condensation :

The formation of carbo-hydrates in the plant is plainly
dependent on the presence of nitrogenous matter, phos-
phates, potash, and the other essential ingredients of
plant-food ; a plant poorly provided with these substances
produces only a small quantity of carbo-hydrates, how-
ever much it be exposed to light. Ti:e formation of glucose
and starch is therefore regarded by some as due to a
splitting up of the nitrogenous protoplasm, the nitro-
genous residue left combining with formaldehyde, and
thus reconstituting the original nitrogenous matter.

FORMATION OF ORGANIC MATTER. 7

The carbohydrate starch (CGH1006) is among the earliest
products ; it is an insoluble substance, and is converted
into sugar (glucose) for the nourishment of distant parts
of the plant, to which it is conveyed by the movement of
the sap. In parts where growth is taking place, and new
cells are being formed, the sugar of the sap is converted
into cellulose, the substance which forms the cell walls,
and of which the whole skeleton of the plant primarily
consists. The conversion of glucose into starch, or of
starch into glucose and cellulose, presents no chemical
difficulties, as all these eubstances are carbo-hydrates,
that is, they are composed of carbon and the elements
of water.

The mode in which albuminoids are formed in the
plant is not certainly known ; probably the nitrates taken
up by the roots are converted into ammonia, the ammonia
into amides, and the amides finally into albuminoids.

The fatty matter of a plant may be formed from
carbo-hydrates ; or possibly from the splitting up of
albuminoids.

The vegetable acids in a plant are probably formed
by oxidation ; most likely by the oxidation of some
of the carbo-hydrates.

We have just referred to oxidation as taking place in
the plant. This is always going on in the interior during
life, and as a result the plant is continually consuming a
small quantity of oxygen, and giving out a small quantity
of carbonic acid, an operation precisely similar to animal
respiration. This action is not readily perceived during
the daytime, being hidden by the opposite action of the
chlorophyll cells, which absorb carbonic acid and evolve
oxygen. If a plant is placed in darkness the respiratory

8 THE CHEMISTRY OF THE FARM.

action becomes manifest. The oxidation of matters already
formed is an important means for the production of new
bodies.

3. Transpiration. — Another important function of
leaves consists in the transpiration of water. This
transpiration takes place through the cuticle of young
leaves, but in older leaves chiefly occurs through small
openings, known as stomata, which are most abundant on
the under side of the leaves. Transpiration takes place
chiefly in light ; it will occur abundantly, even in an
atmosphere saturated with water, if the plant be only
exposed to sunshine. The amount of water evaporated
from the surface of a growing plant is very large. Land
that has lately borne a crop is always much drier than
a bare fallow.

The results of transpiration to the plant are most im-
portant, the evaporation of water from the leaves being a
principal cause of the rise of the sap, and the consequent
drawing up of water from the soil containing plant food
in solution.

Function of the Boots.— The roots of a plant are the
organs by which it absorbs water from the soil, and with
this water a variety of food elements are introduced.

1. Assimilation of Ash Constituents. — The roots take
up the soluble salts, and all the diffusible sub-
stances (those capable of passing through a membrane)
which are present in the water which they draw from
the soil. The plant may thus receive a number of sub-
stances not actually required for its nutrition.

The feeding power of roots is not, however, confined
to the taking up of ready-formed solutions, they are also

FUNCTION OP HOOTS. 9

capable of attacking some of the solid ingredients of the
soil, which they render soluble and then appropriate.
This important action of roots exists in different degrees
with different plants. The action takes place only at the
points of contact between the root-hairs and the particles
of the soil, and is brought about by the acid sap which
the roots contain. This action of the roots plays an
important part in the supply of phosphoric acid and
potash to the plant, as these substances, especially the
former of them, exist in the soil in difficultly soluble
forms, and are rarely found in solution in the water pre-
sent in soils.

An apparently selective power is exerted by plants,
some soluble ash constituents being taken up in much
larger quantity than others, which may actually be more
abundant in the soil. A striking example of this is the
assimilation of potassium in preference to sodium salts.
This selective action of the roots is quite explainable by
the known laws of diffusion. When ingredients of the
sap are removed out of solution by becoming part of the
tissues of the plant, the diffusion of such substances from
the soil will continue : while salts not appropriated by the
tissues can continue to enter by diffusion only so long as
the solution in the soil is stronger than that in the plant.

2. Assimilation of Nitrogen. — Besides furnishing the
plant with its ash constituents, the root has the impor-
tant function of supplying nitrogen; this is nearly
always taken up in the form of nitrates. A plant
is capable of making use of nitrogen in the form of
nitric acid or ammonia ; it is also, according to
several experimenters, able to assimilate nitrogen when
in the form of urea, uric and hippuric acids, and

10 THE CHEMISTRY OP THE FARM.

several other amide bodies. The facility, however, with
which ammonia, and other nitrogenous substances, are
converted into nitric acid in the soil is so great that
nitrates become by far the most important source of
nitrogen at a plant's disposal.

Recent investigations have shown that in some cases
the feeding power of roots is modified to a very consider-
able extent by their union with another vegetable
organism. Thus, according to Frank, the absorption of
food from the soil is in the case of oak, beech, horn-
beam, hazel and chestnut, mainly accomplished through
the medium of a fungus, the mycelium of which com-
pletely covers the root, and is united with it. A remark-
able instance of such an action is afforded by legu-
minous plants. All the members of this family have
tubercles on their roots, unless the plant has been
grown from seed in a sterilised soil. These tubercles
are occasioned by the invasion of an organism, present
in the soil, the character of which has not yet been fully
studied. When the seeds of peas, lupins or vetches,
are sown in sterilised sand, containing the necessary
ash constituents of plants, but no nitrogen, only a
small, dwarfed growth is obtained, and the roots
are not furnished with tubercles. If, however, a minute
quantity of ordinary soil is added, tubercles appear on
the roots, and the plant now grows vigorously. At the
end of the experiment it is found that the quantity of
nitrogen in the crop is far greater where tubercles have
been formed than where they are absent : indeed, in the
former case, the quantity of nitrogen in the crop and soil
at harvest much exceeds that originally present in the
sand, seed, and added soil. This gain of nitrogen has

DESTINATION OF THE ASH CONSTITUENTS. 11

been derived from the free nitrogen of the atmosphere.
These very remarkable results have been obtained by
several independent investigators. They supply a much-
needed explanation of the remarkable power of assimil-
ating nitrogen possessed by leguminous plants.

Destination of the Ash Constituents.— The very weak
solutions taken up by the roots are concentrated in
the upper parts of the plant, the water being rapidly
evaporated by the leaves, as already mentioned. The
essential ash constituents are employed in the forma-
tion of new tissues. The non-essential ash constituents
which have been taken up by the roots are partly
disposed of in a solid form, as a permanent incrus-
tation of the older tissues. The soluble salts which are
not thus disposed of at first accumulate in the sap. They
are finally more or less removed from straw, and prob-
ably from other old tissues, by the washing effect of rain.

The deposition of silica upon the external tissues of
wheat, barley, and other graminaceous plants is a
familiar example of the excretion of a non-essential ash
constituent. Silica is also abundant in the old leaves,
and in the outer bark of many trees, and is commonly found
as an incrusting constituent of old tissues. Insoluble
calcium salts, frequently the oxalate, are also deposited
as incrusting matters in old tissues. These incrustations
are indirectly of service to the plant, as they tend to harden
the tissues, and thus protect them from injury.

Soluble non-essential ash constituents, as chloride of
sodium, are found abundantly in the succulent parts of
plants when such ash constituents have been present in
the soil. They generally diminish in quantity as the

12 THE CHEMISTRY OF THE FARM.

plant matures, and are never stored up in the seed
Both the amount and composition of the ash of suc-
culent plants, as meadow grass, clover, and mangel, are
greatly influenced by the character of the soil, and the
manure applied. The ash of a seed, on the other hand,
is very constant in composition, the result of the
selective power of the plant.

Of the particular action of the ash constituents within
the plant little is known. Phosphoric acid and potash
are undoubtedly the most important of the ash constitu-
ents ; they are always found concentrated in those parts
of the plant where cell growth is most active, as, for
instance, in a growing bud, or in the layer (cambium)
between the wood and bark of a tree ; they are also
abundantly stored up in the seed.

Silica being the most abundant ash constituent of
wheat, barley, oats, and other graminaceous plants,
was long supposed to be essential for their growth, and to
be the ingredient on which the stiffness of their straw
chiefly depended. It has been shown, however, that
maize and oats may be successfully grown without any
supply of silica, and with no perceptible difference as to
the stiffness of the stem. The grass growing on peat
bogs also contains scarcely any silica, though silica is
abundant in ordinary hay. Silica may, however, dis-
charge useful functions. In Wolff's experiments,
although the presence of silica made little difference in
the weight of the oat plant, it considerably increased the
proportion of corn.

Germination.— A seed is constructed with the purpose
of developing a young plant. It contains the " embryo,"

GERMINATION. 13

or germ, which is always extremely rich in albuminoids,
fat, phosphates, and potash. It also contains a store of
concentrated plant food, intended to nourish the young
plant till its root and leaf are developed. In some
seeds, as those of beans and turnips, this store of food is
chiefly located in the "cotyledons," or rudimentary leaves;
in other seeds, as those of the cereals, there is a reserve
of food outside the embryo, in the " endosperm." In the
seeds of the cereals, and of many other plants, the chief
ingredient of the reserve matter is starch. Another class
of seeds, of which linseed and mustard-seed are examples,
contains no starch, but in its place a large quantity of fat.

For germination to take place, moisture, oxygen, and
a suitable temperature are necessary. Under these con-
ditions the seed swells, oxygen is absorbed, a part of the
carbonaceous ingredients is oxidised, heat is developed,
and carbonic acid evolved. During these changes the
solid ingredients of the seed gradually become soluble.
The starch and fat yield sugar. The albuminoids are
converted into peptones and amides — as, for instance,
asparagine. These changes are principally accomplished
by the agency of ferments (enzymes) contained in the
seed. With the soluble food thus formed the radicle and
plumule are nourished. They rapidly increase in size,
emerge through the coats of the seed, and, if the external
conditions are suitable, soon commence their separate
functions as root and leaf. The process of germination
may be easily studied in the ordinary operation of malting
barley.

Seeds buried too deeply in the soil may not germinate
for lack of oxygen. Or if germination takes place the
plumule may fail to reach the surface, the store of food in

14 THE CHEMISTRY OF THE FARM.

the seed being exhausted before the soil is penetrated and
daylight reached. The smaller the seed the less should
be the depth of earth with which it is covered.

Plant Development.— The development of the plant
after germination follows a regular course. With an
annual, which produces seed and dies during the first
season, we have first a great development of root and leaf,
which collect and prepare materials for growth; next
comes the formation of a flower stem ; and lastly, the pro-
duction of flower and seed ; after which the plant dies.

The materials furnished by tho root preponderate in
the young plant, which is always extremely rich in nitro-
gen and ash constituents ; but as the plant matures the
proportion of carbon compounds derived from the action
of the leaves steadily increases. A cereal crop contains
at the time of full bloom all the nitrogen and potash which
is found in the mature crop ; the assimilation of phosphoric
acid continues somewhat later ; the increase of carbon and
silica proceeds as long as the plant is in a green state.

When seed formation begins an exhaustion of the
other parts of the plant sets in; starch, albuminoids,
phosphoric acid, and potash, are transferred from the
root, leaf, and stem, and stored up in the seed. If the
season is a good one, and the development of the seed
fully accomplished, the straw of a cereal crop will be
found at harvest to be very thoroughly exhausted ; while
in seasons of limited production, or deficient maturity of
grain, the straw will retain far more of the materials
acquired during growth. For the same reason straw cut
while the crop is still green is far more nutritive than
when perfect ripeness has been attained.

PLANT DEVELOPMENT. ]5

With a biennial or perennial crop the case is somewhat
different. The first development of root and leaf is the
same as in an annual; but towards the end of summer
there is a storing up of concentrated plant food in the root,
tuber, or stem, to serve for the commencement of growth
in the following spring. In a biennial root crop, the
turnip for instance, the root attains a great size in autumn,
the leaves dying after transferring to the root their most
important constituents. The next season the root throws
up a flower stem, and the store of matter accumulated
during the preceding autumn is consumed in the pro-
duction of seed. With the production of seed the root
is exhausted, and the plant dies.

In trees plant food is stored up at the end of summer
in the pith, the pith rays, and in the layer between the
wood and bark. The leaves which fall in autumn have
lost nearly all their starch, albuminoids, phosphoric acid
and potash, these having been transferred to the stem.
By the action of the sun in spring-time the new buds
swell, the sap rises, the starch and other matters deposited
in the wood during the previous autumn are re-dissolved,
and employed for the production of new growths. The
sugar found in maple sap in spring-time results from
the transformation of starch stored up in the preceding
autumn.

CHAPTER II.

THE ATMOSPHERE AND SOIL.

The Atmosphere. — Its composition — The carbonic acid, ammonia, and
nitric acid which it supplies — The quantity of combined nitrogen,
chlorides, and sulphuric acid contained in rain. The Soil. — Its con-
stituents— Properties of sand, clay, calcareous matter, and humus —
The relation of soil to water — Its relation to heat — The plant food
contained in soil, its quantity and condition — Oxidation in the
soil, nitrification— Movements of salts in soil, losses by drainage — The
absorptive power of soils— Influence of tillage, and draining— Soil
burning.

The Atmosphere.— One hundred volumes of air con-
tain nearly 79 of nitrogen, and 21 of oxygen, with very
small quantities of: other constituents.

The free nitrogen of the atmosphere is apparently
made available to leguminous crops through their root
tubercles (p. 10) ; there is no satisfactory evidence that
it serves as a plant food to other crops.

We have already stated that the whole of the carbon
of plants is obtained from the carbonic acid present in the
atmosphere : 10,000 volumes of air contain nearly 3
volumes of carbonic acid, or about 1 Ib. in 3,200 cubic
yards of air. An acre of a good wheat crop will obtain
from the atmosphere in four months 1 ton of carbon, a
quantity corresponding to a column of air 3 miles in
height. The small amount of carbonic acid in the
atmosphere is made sufficient by the action of winds,
which bring an enormous quantity of air in contact with
both soil and plant.

THE ATMOSPHERE. 17

The atmosphere also contains a very small and variable
quantity of ammonia. Schloesing found near Paris an
average of 1 Ib. of ammonia in 26,000,000 cubic yards
of air. Miintz and Aubin found at the top of the Pic du
Midi 1 Ib. of ammonia in 44,000,000 cubic yards. Accord-
ing to Schloesing the quantity is greatest in warm
southerly winds. The ammonia of the air is directly
absorbed by plants to a small extent; it is chiefly
rendered available through absorption by the soil, and
by means of rain, which brings it in solution to the
earth.

The atmosphere also furnishes a small amount of nitrous
and nitric acid. The nitrogen and oxygen of the atmo-
sphere combine under the influence of electric discharges,
nitrous acid being formed ; this is converted into nitric
acid by the action of ozone, or peroxide of hydrogen.
Nitric acid may also be formed in the atmosphere by the
oxidation of ammonia by ozone and peroxide of hydrogen.

The amount of nitrogen in the form of ammonia and
nitric acid annually carried to the soil by rain, varies in
different years and places. At Rothamsted, in Hertford-
shire, the amount of nitrogen as ammonia in the rain,
mean of five years, is 2'4 Ibs. per acre; the nitrogen as
nitrates and nitrites about 1 Ib. ; the organic nitrogen a
similar quantity. The total nitrogen is thus about 4'4 Ibs.
per acre.* The average of many experiments on the conti-
nent (excluding Paris) gives 10' 18 Ibs. of nitrogen per
acre. The continental average is above the truth for the
open country, many of the determinations having been

* The quantities here given are those obtained in recent experiments
with improved methods. The rain includes the snow, hail and dew
deposited on the rain gauge.

3

18 THE CHEMISTRY OF THE FAKM.

made near towns. In tropical rain the proportion of
nitrogen as nitrates is generally considerably increased.

Chlorides are always present in rain, especially in the
neighbourhood of the sea. At Lincoln, New Zealand, the
chlorides in the rain are equal, on an average, to about 88
Ibs. of common salt per acre per annum ; at Cirencester
they amount to about 40 Ibs.; at Rothamsted the quan-
tity is about 24 Ibs.

The sulphates found in rain at Rothamsted, 'mean of
five years, correspond to about 17 Ibs. of sulphuric anhy-
dride per acre, yearly.

The quantity of chlorides in the rain at Rothamsted is
apparently sufficient for the crops on the farm, mangels
possibly excepted. The sulphates will also to a consider-
able extent meet the demands of most cultivated crops.

The Soil: 1. Constituents. — All soils have been pro-
duced by the disintegration of rocks, through the pro-
longed action of water, air, and frost. The character of a
soil largely depends on the character of the rock from
which it has been derived. Primitive and igneous rocks
yield soils rich in potash ; fossiliferous rocks produce soils
rich in phosphoric acid. The principal ingredients of
soils are sand, clay, carbonate of calcium, and humus ; as
each of these preponderate the soil is said to be sandy,
clayey, calcareous, or peaty.

Sand is either composed of pure quartz (silica), or con-
sists of fragments of more complex minerals — mica, for
example. When the former is the case, the sand will
supply no plant food ; but in the latter case the gradual
decomposition of the mineral will slowly increase the ash
constituents available for the plant.

CONSTITUENTS OF SOIL. 19

Clay is a hydratecl silicate of aluminium, produced by
the decomposition of felspar and other silicates. Pure clay
is a colloid body ; the amount present in any soil is extreme-
ly small. The purest natural clays are mainly composed of
a very line sand, which has the same general composition
as the true clay associated with it. Pure clay is a powerful
cement, causing the coarser particles of the soil to cohere.
A pure silicate of aluminium would furnish no food to a
plant ; clay always, however, contains some potash, and
frequently a notable quantity. It has also the important
property of absorbing and retaining phosphoric acid, am-
monia, potash, lime, and other substances necessary for
plant nutrition.

Carbonate of calcium is beneficial to the soil in many
ways. It preserves the clay in a coagulated condition,
thus making heavy soils friable and pervious to water. It
enables clay to exercise its absorbent power on various salts,
which would otherwise escape its action. It also promotes
the decomposition of vegetable matter, and the formation
of nitrates in the soil. The presence of some salifiable
base is essential for the performance of the chemical
operations belonging to a fertile soil ; the salifiable bases
usually present are either carbonate of calcium, or the
alkalis derived from the decomposition of silicates. The
calcareous matter of soil supplies lime to the plant; lime-
stone also generally contains phosphoric acid.

The humus, or decayed vegetable matter of soils, has
its origin in the dead roots and leaves of a previous
vegetation, or of a previous organic manuring. It acts
effectively as a cement in sandy soils, holding the particles
together ; in a clay soil it increases the porosity. Humus
is the principal nitrogenous ingredient of soils. A black

20 THE CHEMISTRY OP THE FARM.

soil, rich in humus, is sure to be also rich in nitrogen ;
a soil destitute of humus will contain scarcely any nitrogen.
The fertility of virgin soils is largely due to the nitro-
genous humus which they contain. Humus appears to
possess in part an amide nature ; it yields ammonia and
soluble nitrogenous bodies when acted on by acids or
alkalis, and probably, to a much less extent, under the
action of water.

2. Relation to Water. — The power of absorbing
water from damp air known as hygroscopicity, is
scarcely at all possessed by sand, but to a greater degree
by clay and humus. Schlossing found that while dry
siliceous sand absorbed nothing, a strong clay absorbed
3'5 per cent., and a garden soil 5*2 per cent. Water thus
absorbed is insensible, and can have little direct influence
in plant nutrition. All soils condense water from the
atmosphere when their temperature is below the dew
point.

Sand has the least, and humus the greatest capacity for
retaining water. Schloesing found that fine sand, saturated
with water, and thoroughly drained, retained 7 per cent.; a
clay soil 35 per cent. ; and a forest soil 42 per cent. Light
sandy soils thus suffer most from drought, while applica-
tions of farmyard manure, or the ploughing in of green
crops, increase the water-holding power of a soil by in-
creasing the proportion of humus.

Capillary attraction, by which water is raised from
the subsoil to the surface in dry weather, depends on the
distance between the particles of the soil ; it is least in
open sandy soils composed of coarse particles, and
grea.test in the case of loam or clay.

KELATION OF SOIL TO HEAT. 21

Evaporation is greatest when the soil is occupied by
a crop, and will be in proportion to the activity of its growth
and the extent of its root development. On uncropped soil
evaporation is greatest when the soil is consolidated, and
the conditions are consequently favourable to capillary
action. The presence of stones on the surface tends to
diminish evaporation. Evaporation is least when the
surface soil has been broken up by tillage, as the subsoil
water cannot then reach the surface by capillary attraction.
The amount of water draining through a soil depends on
the amount of the evaporation, and is most simply ex-
pressed as equal to the rainfall, minus the quantity
evaporated.

3. Relation to Heat.— A. soil shaded by a crop is far
cooler than a bare soil. Dark-coloured soils absorb the
greatest amount of heat from the sun's rays, and light-
coloured soils least. The presence of humus is thus
favourable to soil warmth. Quartz sand is an excellent
conductor of heat ; chalk is a bad conductor. A soil rich
in sand will thus be warmed or cooled more rapidly, and
to a greater depth, than a soil containing but little sand.
AVater has a very considerable effect in cooling a soil,
partly from its high specific heat, and partly from the
immense consumption of heat during its evaporation.
During spring and summer a wet soil is always colder
than a dry one. The drainage of wet land will thus
result in a greater warmth of the surface soil, and con-
sequently an earlier growth in spring.

4. Plant Food in Soil. — The proportion of plant food
present in soils is very small, even when the soil is ex-

22 THE CHEMISTEY OF THE FARM.

tremely fertile. The surface soil (first nine inches) of a
pasture may contain when dry O25 of nitrogen per cent.,
while soil of the same depth from an arable field may yield
0*10 — 0*15 per cent., and a clay subsoil 0'05 per cent.
A good surface soil may contain 0*20 per cent, of phosphoric
acid, or not unfrequently a smaller quantity. Potash
varies much, rising to 1*0 per cent, or more in some clay
soils, but being generally much smaller.

The weight of soil on an acre of land is, however, so
enormous, that small proportions of plant food may amount
to very considerable quantities. Nine inches' depth of
arable soil (clay or loam) will weigh, when perfectly dry,
about 3,000,000 or 3,500,000 Ibs. A pasture soil will be
lighter, the first nine inches weighing when dried and the
roots removed about 2,250,000 Ibs. Supposing, therefore,
a dry soil to contain O'lO per cent, of nitrogen, phosphoric
acid, or potash, the quantity in nine inches of soil will be
from 2,250 Ibs. to 3,500 Ibs. per acre.

A large part of the elements of plant food contained in
soils is present in such a condition that plants are unable
to make use of it. An acre of soil may contain many
thousand pounds of phosphoric acid or of nitrogen, and
vet be in a poor condition ; while a dressing supplying
50 Ibs. of readily available phosphoric acid, or nitrogen,
in the form of superphosphate or nitrate of sodium, may
greatly increase its productiveness.

The fragments of silicates or limestone present in soil,
as stones, gravel, and sand, are as a rule of little value to
a plant, the elements of plant food which they contain
being mostly in too insoluble a condition to be attacked by
the roots. These fragments of rock may, however, be
slowly decomposed by the mechanical action of frost, and

OXIDATION IN SOIL. 23

by the chemical action of water, and their contents thus
gradually made available to the plant. The solvent power
of the water in a soil is greatly increased by the carbonic
acid, and perhaps also by the humic acids it holds in
solution. Water containing carbonate of calcium in
solution is especially capable of attacking silicates.

The chemical analysis of a soil, though always of great
value, does not enable us to fix its degree of fertility
owing to the imperfect information it affords as to the
condition of the plant food.

5. Oxidation in Soil. — The materials from which the
nitrogen of soils is originally derived contain generally a
large proportion of carbon. In the roots and stubble of
cereal crops the relation of nitrogen to carbon is 1 : 43 ; in
those of leguminous crops 1 : 23 ; in moderately-rotted
farmyard manure about 1:18. In the soil these materials
are oxidised, chiefly by the action of various living organ-
isms (insects, worms, fungi, bacteria), large quantities of
carbonic acid being produced. As a result of this loss
of carbon, we find that the surface soil of a pasture
(roots removed) will contain about 1 of nitrogen to 13
of carbon ; the surface soil of an arable field about 1:10;
and a clay subsoil 1 : 6.

The nitrogen contained in humus is not in a condition
to serve as a general plant food; cereal crops are apparently
unable to appropriate it ; some crops may, however, pos-
sibly assimilate some humic matters. For the nitrogenous
matter of humus to become available to crops it must be
farther oxidised ; this is accomplished by certain bacteria
in the soil, carbonic acid, ammonia, and finally nitric acid
being produced. The nitrifying bacterium occurs abun-

24 THE CHEMISTRY OF THE FA KM.

dantly in the surface soil ; the depth to which its action
extends depends on the porosity of the subsoil. Nitrifi-
cation only takes place in a moist soil, sufficiently porous
to admit air. It is also necessary that some base should
be present with which the nitric acid may combine : this
condition is usually fulfilled by the presence of carbonate
of calcium, nitrate ot calcium being produced. Nitrifica-
tion is most active at summer temperatures; it ceases
apparently near the freezing-point.

Oxidation is most active in soils under tillage. In
arable land the production of available plant food is at its
maximum, and so is also the waste by drainage. The
nitrogenous humic matter of arable land is maintained
only when the new supply from crop residues and organic
manures is equal to the amount annually oxidised. In an
untilled pastur.e or forest soil, on the other hand, a con-
siderable accumulation of organic matter may take place,
the annual residue of dead roots and leaves being generally
in excess of the means of oxidation. In a peat bog oxida-
tion is further checked by a high water level, which ex-
cludes air from the soil ; here an unlimited accumulation
of organic matter may take place if plants capable of grow-
ing under the circumstances are present.

6. Movements of Salts in Soil. — If water is allowed
to drain through a soil it carries with it a part of the
readily soluble matter which the soil contains. The sub-
stances chiefly removed by the water will be carbonate
of calcium, and the nitrates, chlorides, and sulphates of
calcium and sodium. When heavy rain falls these sub-
stances are washed into the subsoil, and partly escape by
the nearest outfall into the springs, brooks, nnd rivers.

MOVEMENTS OF SALTS IN SOIL. 25

The loss of nitrates from highly manured land during a
wet season is very considerable, and will frequently be
equal to several hundred pounds of nitrate of sodium per
acre. When dry weather sets in evaporation takes place
at the surface of the soil, the water of the subsoil is slowly
brought again to the surface by capillary attraction, and
the salts it contains are concentrated once more in the
upper soil, forming in some rare instances a white crust
of salt upon the surface. Capillary attraction has little
influence in the case of sandy soils.

Besides the rapid movements of salts due to a movement
of the water in the soil, they have also a slow movement
due to their molecular diffusive power, by which their par-
ticles continually pass from a stronger solution to one
weaker. This movement is always in action in moist soil,
and tends to the equal distribution of all soluble matter.
If a dressing of nitrate or chloride of sodium is applied to
moist soil, the manure will dissolve and slowly spread
downwards, even before rain falls. Again, when a heavy
rain has washed all soluble salts out of the surface soil,
they will slowly rise again by diffusion as soon as rain
ceases.

Of the soluble and diffusible salts occurring in soil the
nitrates are of the greatest importance as plant food. The
quantity of nitrates in a surface soil will vary greatly,
depending on the richness of the soil in nitrogen, the
previous conditions as to temperature and moisture, the
extent of recent washing by rain, and on whether the soil
is or is not under crop. Where a crop is growing the
nitrates will be kept nearer the surface, the evaporation
of water from a growing crop being far greater than from
a bare soil. The nitrates will also be constantly taken up

26 THE CHEMISTRY OP THE FAEM.

by the roots and employed as plant food. The loss of
nitrates by drainage is thus far less when the land is under
crop than in the case of a bare fallow.

7. Absorptive-Power of Soil. — The surface of a moist
fertile soil is capable of absorbing ammonia from the
atmosphere. This absorption may proceed continuously
if the ammonia absorbed is continuously converted into a
nitrate. The amount that may be so absorbed may
apparently become considerable when the soil is in a
suitable condition as to porosity, and as to its capacity
for effecting nitrification. Whether free nitrogen is ever
brought into combination by any of the constituents of
soil is at present a disputed point.

If a solution containing phosphoric acid, potash, or
ammonia is poured on a sufficiently large quantity of
fertile soil, the water which filters through will be
found destitute of these substances. This retentive
power of soil for phosphoric acid, potash, &c., is of the
utmost importance in agriculture. The action is a com-
plex one. All salts are doubtless retained to some extent
by soil through mere mechanical adhesion ; salts, thus
feebly retained, as nitrates and chlorides, can be easily
removed by washing with water. Other substances are,
on the contrary, retained by chemical affinity ; these are
not removed by washing, or but to a small extent. The
ingredients of the soil which exercise a chemical retentive
power, are the hydrates of ferric oxide and alumina, the
hydrous silicates of aluminium, and humus.

Ferric oxide is a common ingredient of soils ; to it the
red colour of many soils is owing. To the presence of
ferric oxide the retention of phosphoric acid is chiefly

ABSORPTIVE-POWER OF SOIL. 27

due, an insoluble basic phosphate of iron being- produced.
Alumina acts in the same manner. Ferric oxide and
alumina have also a retentive power for ammonia and
potash, but the compounds formed are more or less de-
composed by water. To the hydrous silicates the perma-
nent retention of potash and other bases is probably
chiefly due. Humus has a great absorbent power for
ammonia. Other bases, as magnesia and lime, are also
retained by soil, but in a less powerful manner than are
potash and ammonia.

Soils destitute of carbonate of calcium retain very
little potash or ammonia when these are applied as salts
of powerful acids, as for instance as chlorides, nitrates,
or sulphates. When carbonate of calcium is present the
potassium or ammonium salt is decomposed, the base is
retained by the soil, while the acid escapes into the
drainage-water united with calcium. The addition of
marl, chalk or lime may thus greatly increase the reten-
tive power of a soil for bases.

The fertility of a soil is nearly connected with its power
of retaining plant food. In the case of a soil containing
clay, only traces of phosphoric acid, ammonia, or potash
are ever found in the drainage- waters. Sandy soils, from
their smaller chemical retentive power and free drainage,
are of less natural fertility, and dependent on immediate
supplies of manure.

There can be little doubt that the active plant food con-
tained in soil, which is capable of being taken up by roots,
exists either in solution, or in the states of combination
just referred to — that is, in union with ferric oxide, hy-
drous silicates, and humus. Different crops have very diff-
erent powers of attacking these various forms of plant food.

28 THE CHEMISTRY OF THE FARM.

8. Tillage and Draining. — The operations of tillage
and draining serve in many important ways to increase
the amount of plant food which is at the disposal of a
crop ; some of these have been already noticed.

By tillage, and the action of frost, the surface soil is
pulverised, and brought into an open porous condition,
favourable both for the distribution and action of roots.
As the absorbent power of roots resides entirely in the
root-hairs, a finely divided condition of the soil is essential
for the rapid development of a plant. Capillary attraction
is diminished by tillage, and the land consequently suffers
less from drought; the amount of drainage is at the same
time increased. By the destruction of weeds the whole
of the plant food is left available for the crop. Another
important result of tillage is that the soil is thoroughly
exposed to the influence of the air. Soils containing
humus or clay will absorb some ammonia from the atmo-
sphere, and thus increase their store of nitrogen. The
oxidation of the nitrogenous organic matter of the soil,
and the production of nitric acid, have been already
noticed, as also the disintegration and solution of the
particles of rock contained in soil. Of the various results
brought about by tillage, the increased production of
nitrates must be ranked among the most important.

By means of pipe-drainage the various chemical actions
just mentioned are carried down to a greater or less extent
into the subsoil, for, as the water level is lowered, the air
enters from above to fill the cavities in the soil. By
draining the depth to which roots will penetrate is also
increased, for roots will not grow in the absence of oxygen,
and rot as soon as they reach a permanent water level. In
a water-logged soil deoxidation is active, the nitrates pre-

SOIL BURNING. 29

sent are destroyed, a part of the nitrogen being evolved as
gas ; the soil may thus suffer a considerable loss of plant
food.

Natural drainage in stiff soils is effected by original
fissures, by cracks produced in dry weather, and especially
by channels left on the decay of deeply-rooted crops, and
by worms. The porosity of stiff soils is largely increased
by the two agencies last named.

9. Burning. — Burning is occasionally resorted to as a
means of increasing the available plant food, and improv-
ing the texture of a heavy soil. The soil is burnt in heaps,
which are then spread over the land. If the soil contains
limestone, it is easy to see that the phosphates of the lime-
stone may become more available by the complete
disintegration which attends the conversion into lime.
The lime will also attack the silicates of the soil at a high
temperature, and liberate a part of the potash from its
insoluble combinations. To produce the best results it is
essential that the burning should take place at a low tem-
perature. This treatment by burning is a very extreme
one, and can be recommended only in few cases; it must
always be attended with an entire loss of the nitrogen in
the soil burnt. The ploughing in of burnt clay is of use
in improving the texture of heavy land.

CHAPTER III.

MANURES.

Difference between natural vegetation and agriculture — Necessity for
manuring. Farmyard Manure. — Circumstances which influence its
character— Losses in preparation — Changes during fermentation —
Its average composition — Slowness of its effect — Seaweed — Guano —
Fish Manure, — Sulphate of Ammonium — Nitrate of Sodium — Soot,
Dried Blood, Powdered Horn, and Woollen Refuse — Meat Meal,
Meat Guano —Bones — Oilcakes — Phosphatic Slag and ground Phos-
phates— Superphosphate — Gypsum — Lime, Chalk, and Marl —
Potassium Salts — Common Salt — Application of Manures. — Impor-
tance of thorough distribution — Best time for application. Return
for Manure Applied. — Increase from nitrogenous manures — Effect
of residues of previous manuring.

IN the natural vegetation of a forest or prairie the soil
suffers no diminution of plant food. The elements taken
from the soil are returned to it on the decay of the plants
which the soil has nourished, or on the death of the
animals which have fed on these plants. Under these
circumstances the surface soil becomes rich in carbon and
nitrogen, the quantity contributed by the atmosphere
at first exceeding, and then balancing, all losses. The
surface soil also becomes rich in the ash constituents of
plants, these being collected from the subsoil by the roots,
and left at the surface on the decay of the plant. A
virgin soil thus generally contains an abundance of plant
food, and will produce large crops without manure.

As soon as land is brought under the plough the
oxidation of the organic matter previously accumulated
commences. The vegetable and animal produce of the
land are also now consumed off the soil which has reared

FARMYARD MANURE. 31

them. Provision must consequently be made, sooner or
later, to return to the land a part at least of the plant
food removed from it, if permanent fertility is to be
maintained. Hence the necessity for manuring.

The most complete return to the land would be ac-
complished by manuring it with the excrements of the
men and animals consuming the crops. This is partially
done by the application of farmyard manure ; but the con-
gregation of men in cities, and the difficulty of employing
sewage with profit, prevent this plan being thoroughly
carried out. The farmer is thus generally obliged to
purchase manures for the land in exchange for the crops
and stock sold off it.

On very poor soils it is necessary to make a very com-
plete return of all the elements of plant food removed by
the crops, but in most soils there is an abundance of some
one or more of these elements, and a partial manuring will
consequently suffice. With high farming the contribu-
tions to the soil may be in excess of the exports, and the
land consequently increase in fertility. The nature of
the exhaustion resulting from the growth of particular
crops, and the economic application of manure to meet
their special requirements, will be considered in Chapter
IV. ; the losses during a rotation of crops in Chapter Y. ;
the losses by the sale of animal products in Chapter VI.

Farmyard Manure consists of the liquid and solid
excrements of the farm stock, plus the litter employed.
Its composition will vary according to the character of
the animals contributing to it, the quality of their food,
and the nature and proportion of the litter. This part of
the subject will be discussed in Chapter IX.

32 THE CHEMISTRY OF THE FARM.

The treatment of the manure is most important. A
large proportion of the nitrogen is voided in the form of
urine, and generally the richer the diet the higher will
this proportion be. If, therefore, the liquid manure is
lost, or the solid matter is washed by rain, and the
washings are allowed to drain away, serious losses of
nitrogen and potash will occur. Hence the superiority
of box manure to that made in an open yard.

It must also be recollected that the urea, which forms
the chief nitrogenous ingredient of urine, is speedily
changed by fermentation into carbonate of ammonium,
and as this is a volatile substance a considerable loss of
nitrogen will easily occur. This loss takes place chiefly
in the first few days, while the manure is in the stall ; it
is greatest with animals yielding a concentrated urine, as
horses and sheep. The loss may be diminished by a
liberal use of litter, and especially by using peat, spent
tan, sawdust, or peat moss instead of straw. The
addition of earth (not sand or chalk) to straw increases
its power of retaining ammonia. Sprinkling powdered
gypsum also diminishes the loss of ammonia. The am-
monia present in fresh manure gradually disappears,
apparently combining with the organic substances arising
from the decomposition of the litter.

Farmyard manure rapidly undergoes fermentation. If
placed in a heap the mass gets sensibly hot, and a large
quantity of carbonic acid, and some marsh gas, are given
off. Fermentation is most active when the manure lies
loosely, more air then coming in contact with it; it is
least active when the manure heap is consolidated. When
fermentation occurs in consolidated, moist manure, in
a place protected from rain, a considerable part of the

FARMYARD MANURE. 33

carbonaceous matter is destroyed, but little loss of
nitrogen takes place ; if , however, the manure gets dry
and mould appears, a serious loss of free nitrogen may
occur. Eotten manure, when well made, is more concen-
trated than the fresh, having greatly diminished in weight
during fermentation, with but little loss of valuable con-
stituents. Some of the constituents have also become
more soluble. Manure heaps in the open field should
be protected from waste by covering them with a layer
of earth 6 inches thick.

Farmyard manure will contain from 65 to 80 per cent,
of water. The nitrogen maybe 0'40 to 0*65 per cent., or
higher, if produced by highly fed animals, or with peat
moss litter. The ash constituents will be 2*5 to 3 per
cent., exclusive of the sand and earth always present.
Of these ash constituents 0*4 to 0*7 will be potash; and
O2 to 0*4 phosphoric acid. One ton of farmyard manure
will thus supply 9 — 15 Ibs. of nitrogen, a similar
amount of potash, and 4 — 9 Ibs. of phosphoric acid.

Farmyard manure is a " general" manure; that is, it
supplies all the essential elements of plant food. The
immediate return from an application of farmyard manure
is much less than from the same amount of plant food
applied in artificial manures. The effect of farmyard
manure is spread over a considerable number of years, its
nitrogen being chiefly present not as ammonia but in the
form of carbonaceous compounds, which decompose but
slowly in the soil.

Farmyard manure improves the physical condition of
the soil, by increasing the proportion of humus present.

Seaweed.— This manure when fresh is, on the whole,

34 THE CHEMISTRY OP THE FARM.

similar in value to farmyard manure. It becomes more
valuable as it loses water.

Guano.— This manure consists chiefly of the dried ex-
crements of sea fowl. When guano has been deposited
in the absence of rain it contains a large amount both of
nitrogenous matter and phosphates. If exposed to rain
the original nitrogenous matter is decomposed, and the
nitrogen volatilised in the form of carbonate of ammonium ;
the guano remaining is then almost purely phosphatic.
Ichaboe guano, for example, is a recent deposit, containing
about 12 per cent, of nitrogen, and 10 per cent, of
phosphoric acid ; while Arbrohlos guano is a phosphatic
guano, containing 1 per cent, of nitrogen, and 33 per cent,
of phosphoric acid. The largest deposits of guano are on
the Peruvian coast and the adjacent islands. The present
imports contain 4 — 8 per cent, of nitrogen, 14 — 23 per
cent, of phosphoric acid, and 2 — 4 per cent, of potash.
From its great variation in composition guano should
always be purchased on analysis.

In a nitrogenous guano the nitrogen is chiefly present
as uric acid, and as ammonium salts. The strong smell
of a damp guano is due to carbonate of ammonium.
The phosphoric acid exists principally in the form of
phosphate of calcium, but in nitrogenous guanos a small
part exists as phosphate of ammonium, a salt readily
soluble in water.

Damp Peruvian guano is sometimes treated with a
small proportion of sulphuric acid, it is then called " Dis-
solved guano.9' Such guano contains no volatile carbon-
ate of ammonium, and nearly the whole of the phosphates
has become soluble in water.

FISH MANURE. 35

Nitrogenous guano is a highly concentrated manure,
and may be employed with excellent effect for corn crops,
potatos, and roots. Phosphatic guanos may be employed
for turnips, but such guanos are more usually converted
into superphosphate before they are applied to the land.

Pish Manure.— This consists of fish refuse dried and
powdered. It contains usually 7 — 8'5 per cent of nitrogen.
That made from cod contains 13-14 per cent of phos-
phoric acid as phosphate of calcium, and that made from
haddock and herring 6 — 9 per cent. If much oil is present
the value is diminished, as the manure decomposes more
slowly in the soil.

Sulphate of Ammonium.— This substance is prepared
from the ammoniacal products of gas works, coke ovens,
bone distilleries, &c. In its crystallised form it is the
most highly nitrogenous of all the manures at a farmer's
disposal, containing 24 — 25 per cent, of ammonia, or 19'8
— 20' 6 per cent, of nitrogen.

It should be ascertained that the manure is free from
sulphocyanate of ammonium, as this substance is very
injurious to plants. If sulphocyanates are present, a solu-
tion of the salt will become blood-red on the addition of
ferric chloride.

Sulphate of ammonium is a " special " manure, valua-
ble solely for its nitrogen. It is a powerful manure for
corn crops, for which it is best employed in conjunction
with superphosphate. Admixture with phosphates and
potassium salts is more necessary for obtaining a profit-
able result with ammonium salts than it is when nitrate
of sodium is employed.

36 THE CHEMISTEY OF THE FARM.

The ammonia is converted into nitrates in a few days
or weeks after the application of the salt to a moist, fer-
tile soil. The use of sulphate of ammonium is attended
with some loss of lime to the soil, as both the sulphuric
acid, and the nitric acid subsequently formed, unite with
the lime of the soil, and the resulting salts are more or
less removed by drainage. Ammonium salts produce
little effect in soils destitute of lime.

Nitrate of Sodium.— An enormous deposit of the
crude salt, containing much chloride of sodium, is found
in Peru. The nitrate sent to this country has been puri-
fied by crystallisation; it contains 95 — 96 percent, of real
nitrate, or 15 '6 — 15*8 per cent, of nitrogen. The most
usual impurity is common salt.

This manure, like the preceding, is valuable solely for
its nitrogen. It is an excellent manure for all crops re-
quiring artificial supplies of nitrogen, especially corn
crops and mangels. For corn crops it is best employed
together with superphosphate. Nitrate of sodium should
not be mixed with a damp superphosphate, else nitric
acid will be lost on keeping. The two manures may be
mixed immediately before use; or the superphosphate
may be sown with the corn, and the nitrate applied
afterwards as a top dressing.

The return from the use of nitrate of sodium is
generally greater than from the use of the same quantity
of nitrogen as sulphate of ammonium. The nitrate is
especially better in dry seasons ; in wet seasons the am-
monium salt sometimes has the advantage.

Nitrate of sodium is especially suited for clay land.
The soda which it leaves in the soil apparently helps to

SOOT, DEIED BLOOD, &C. 37

render the potash and phosphates in the soil available to
crops. It is quicker in its action than any other nitro
genous manure, and is therefore the best manure to em-
ploy when a late dressing has to be given.

Soot, Dried Blood, Powdered Horn, and Woollen Refuse

are all purely nitrogenous manures. Soot owes its value
to the presence of a small and variable quantity of am-
monium salts. In good house soot the nitrogen may be
3*5 per cent. Dried blood is an excellent manure, con-
taining 9 — 12 percent, of nitrogen. Hoofs and horns are
extremely rich in nitrogen, the proportion being usually
15 per cent. Shoddy, and other forms of wool, are very
variable in composition, owing to the different proportions
of water, cotton, dirt, and grease which they contain ; the
nitrogen will generally range from 5 to 8 per cent.

The nitrogen of blood, horn, wool, and hair is not in a
form suitable as plant food. Blood readily decomposes
in the soil, yielding first ammonia, and then nitric acid.
Horn, wool, and hair decompose much more slowly, and
their effect is spread over many years.

Soot is generally employed as a top dressing for
spring corn. Dried blood is an excellent manure for wheat.
Wool and hair are chiefly used for hops.

Meat Meal, Meat Guano.— This is the residue from
the manufacture of meat extract. It varies in com-
position according to the amount of bone ground up with
the meat fibre. The nitrogenous kinds contain 11 — 13 per
cent, of nitrogen, and O6 — 3*0 per cent, of phosphoric acid.
The phosphatic kinds contain 6 — 7 per cent, nitrogen, and
14 — 17 percent, phosphoric acid.

38 THE CHEMISTRY OF THE FARM.

Bones.— These are largely employed as manure ; the
fat is usually first extracted by steaming. Commercial
bones contain about 3'6 per cent, of nitrogen, and 23 per
cent, of phosphoric acid, existing as phosphate of calcium.
Bones that have been boiled to extract the gelatin con-
tain about 1'4 per cent, of nitrogen, and 29 per cent, of
phosphoric acid.

Bones decompose but slowly in the soil, especially on
heavy land ; their effect is thus spread over several years.
The finer the bones have been ground the more immedi-
ate is their effect. Bones are usually employed for pas-
ture, and for turnips.

Oilcakes. — Cakes of little or no value for feeding
purposes are used when ground as manure ; their value
is considerable, as they contain a good deal of nitrogen,
with phosphates and potash. See p. 139.

Fhosphatic Slag, and Ground Phosphates.— Some
phosphates when finely ground may be successfully em-
ployed as manure without previous conversion into super-
phosphate. The phosphates most suitable for this pur-
pose are Thomas' slag, phosphatic guanos and bone-ash.
Phosphatic slag contains generally 15 — 20 per cent, of
phosphoric acid ; it is now employed in enormous quanti-
ties. The soils most suitable for such manures are those
rich in humus, and poor in carbonate of calcium ; these
being the conditions (presence of humic and free carbonic
acid) most favourable to the solution of phosphate of
calcium. Moorland and pasture soils are especially suit-
able for such treatment. Thomas' slag is an effective
manure for swedes and early turnips. Undissolved phos-
phates must be employed in extremely fine powder.

SUPERPHOSPHATE. 39

Superphosphate.— An abundance of mineral phos-
phates (phosphates of calcium) occur in nature ; many of
these are so little soluble that their effect as manure is
but slight; by treating them with sulphuric acid (sp.
gr. 1*55) the sparingly soluble tricalcic phosphate is con-
verted into phosphoric acid, or into soluble monocalcic
phosphate, sulphate of calcium being at the same time
produced. Superphosphate is thuy a mixture of phos-
phoric acid and monocalcic phosphate, with gypsum, and
various impurities (as sand, and compounds of iron and
aluminium), derived from the original mineral. A super-
phosphate will generally contain more or less of un-
dissolved phosphate ; this amount will be more consider-
able if the manure is badly made.

The value of a superphosphate chiefly depends on the
percentage of "soluble phosphate " present. By this
tsrm analysts do not mean monocalcic phosphate, but
the quantity of tricalcic phosphate rendered soluble.

Besides the soluble phosphate, and the undissolved
phosphate, a superphosphate will frequently contain what
is known as "reduced phosphate," — that is, phosphate
which was once soluble but has now lost this character.
The diminution of soluble phosphate during the storing
of superphosphates chiefly occurs when the manure has
been made from materials containing ferric oxide and
alumina, and is due to the formation of ferric and
aluminic phosphate. The proportion of reduced phos-
phate present in a superphosphate is estimated from its
insolubility in water, but solubility in a solution of citrate
of ammonium. Eeduced phosphate has an agricultural
value between soluble and undissolved phosphate.

The best mineral phosphate found in England is Cam-

40 THE CHEMISTRY OF THE FAEM.

bridge coprolite. This is not at present much used,
cheaper phosphates being imported. Immense quantities
of mineral phosphates are imported from South Carolina,
Belgium, Spain, and Canada, besides considerable quan-
tities of phosphatic guano.

The superphosphates richest in soluble phosphate (40
to 45 per cent.) are prepared from phosphatic guanos.
Bone ash, and some phosphorites, also yield high quality
manures. The great bulk of our superphosphates is at
present prepared from Carolina phosphate ; such manure
will contain 23 to 27 per cent, of soluble phosphate.

Superphosphates form the basis of almost all manu-
factured manures. By using bones, or ground horn, or
by adding shoddy or crude ammonium salts, turnip
manures are produced containing a small amount of nitro-
gen. By mixing with the superphosphate a larger
amount of ammonium salts, and in some cases potassium
salts, the articles sold as corn, grass, mangel, and potato
manures are prepared. Superphosphate made largely
from bones is known as dissolved bones.

When superphosphate is applied to a soil containing
carbonate of calcium the soluble phosphate is speedily
precipitated, but in a form easily taken up by the roots
of plants. In most cases the phosphoric acid is finally
converted into basic phosphate of iron, a substance less
easily assimilated by the roots; fresh applications of
phosphates are thus more effective than the residues of
previous manuring.

Superphosphates are naturally more speedy in their
effect than manures consisting of undissolved phosphate.
A small quantity of phosphoric acid applied as super-
phosphate will generally have as great immediate effect

GYPSUM. 41

as a considerable quantity applied as bones or ground
phosphate.

Superphosphate is chiefly employed for turnips, for
which it is invaluable ; it is also of considerable use for
corn crops, especially barley. Its use tends to early
maturity in the crop.

Gypsum.— Tnis manure consists of sulphate of cal-
cium • it is of very limited value. Gypsum is most suit-
able for crops, such as clover and turnips, which require
a considerable amount of sulphur. As superphosphate
always contains much gypsum special applications of
gypsum will be unnecessary where superphosphate is
employed. Finely-powdered gypsum is sometimes
employed in stables to hinder the volatilisation of ammo-
nium carbonate. Crude potassium salts act in the same
manner, owing to the magnesium salts which they con-
tain.

Lime, Chalk, and Marl are frequently manures of the
greatest importance. On soils naturally destitute of
lime, as is the case with many clays and sandstones,
these manures will supply an indispensable element of
plant food. Some marls will also supply a notable quan-
tity of phosphoric acid. In most cases, however, the
beneficial influence of these manures is due to the che-
mical actions which lime performs in the soil ; the chief
of these have been already glanced at (see p. 19).

Burnt lime is much more powerful in its action on
vegetable matter than chalk or marl; it should be used
with discrimination, lest the humus of the soil be unduly
diminished. Heavy clays, or soils rich in humus, are

42 THE CHEMISTEY OF THE FARM.

those most benefited by burnt lime. In reclaiming peat
bogs lime is of the highest value. The acid humic matter
of the peat is neutralised by the lime, and the conditions
thus made suitable for the oxidation of the nitrogenous
organic matter and the production of ammonia and
nitrates.

The general effect of lime is to render available the
plant food already in the soil, without itself supplying
any significant amount ; liming cannot, therefore, be
successfully repeated except at considerable intervals.

Potassium Salts. — These salts are now obtained from
Stassf urt and Leopoldshall in large quantities ; they form
a thick deposit overlying an enormous mass of rock salt.
The commonest potassium salt employed as manure, is
'kainite ; it consists of chloride of potassium, sulphate of
magnesium, and water, with the chlorides of sodium and
magnesium in addition. Kainite will contain about 13
per cent, of potash.

Wood ashes may also be employed as a potash
manure ; they will contain between 5 and 10 per cent, of
potash. The ash of young boughs is richer than that
from full -si zed timber.

Potash manures produce their greatest effect on pas-
ture ; clover, potatos, and root crops may also be bene-
fited by their use. Many soils, especially clay soils, are
naturally well furnished with potash; on these soils
potash manures are almost without effect.

Common Salt.— Chloride of sodium supplies no essen-
tial ingredient of plant food. Salt is commonly used for
mixing with nitrate of sodium, and as a manure for

APPLICATION OF MANUEES. 43

mangels. The little value which it possesses is probably
due to its action in the soil, where it may help to set free
more important constituents.

Application of Manures.— A manure can be efficacious
only when its constituents are brought into contact with
the roots of the crop. To obtain this contact to the fullest
extent the manure must be thoroughly and evenly distri-
buted throughout the depth of soil mainly occupied by the
roots. Soluble manures — as nitrate of sodium, chloride
of sodium, ammonium salts, potassium salts, and super-
phosphate— have the great advantage that they distribute
themselves within the soil after the first heavy shower far
more perfectly than can be done by any mode of sowing.
Whenever possible, manure should be reduced to a fine
powder before application. Artificial manures, if distri-
buted by hand, should first be made up to a considerable
bulk by mixing with fine dry soil or ashes. Manures con-
taining ammonia must not be mixed with alkaline ashes
or with Thomas' slag, else some of the ammonia will be
lost. When manure is especially required by the plant
in its earliest stages — as superphosphate for turnips — it
may be drilled with the seed ; but, as a rule, manure
should be sown broadcast, and ploughed or harrowed in.

Top-dressing, that is, sowing manure on the surface
of land already under crop, should generally be confined
to manures that are soluble, or the principal constituents
of which easily become soluble in the soil. Nitrate of
sodium is sown with advantage in this manner if showery
weather can be depended on to distribute the manure in
the soil. On pasture all manures are necessarily applied
as top-dressings.

44 THE CHEMISTEY OF THE FAKM

Manures of little solubility, or those for which the soil
has a great retentive power, may be applied to the land
before the growing period of the crop commences. Diffu-
sible manures, on the other hand, should be applied only
when the crop is ready to make use of them, else serious
waste may occur by drainage. Farmyard manure, sea-
weed, fish manure, blood, horn, wool, meat guano,
oilcakes, bones, and ground phosphates, and to some
extent superphosphate and potassium salts, belong to
the former class; while nitrates, and all manures con-
taining ammonia, belong to the latter class. It was
formerly supposed that the great retentive power of
fertile soils for ammonia would effectually prevent any
loss by drainage ; we know now that ammonia is speedily
converted into nitrates after mixing with the soil, and
that these nitrates are "readily washed out by heavy rain.

Following these principles, an autumn manuring for
wheat may consist of farmyard manure, blood, or shoddy,
with or without superphosphate ; but dressings of guano,
ammonium salts, or nitrate of sodium should be deferred
till the spring. The question is, however, clearly one of
climate, and with a dry winter climate ammonium salts or
guano may be applied with advantage in the autumn. In
a wet spring loss maybe avoided by applying ammonium
salts, and especially nitrate of sodium, in small successive
dressings instead of in one application. Late applications
of nitrogenous manure are, however, apt to produce straw
rather than corn.

On soils of open texture, and little retentive
power, preference must often be given to manures of
little solubility, in order to diminish the loss occa-
sioned by heavy rain; organic manures, as farmyard

EETUEN FOE MANUEE APPLIED. 45

manure, seaweed, or oil-cakes, are in such cases very
suitable.

Return for Manure Applied.— No dressing of manure
is completely taken up by the crop to which it is applied,
dressings larger than the actual requirements of the crop
must therefore be employed to obtain a given result. At
Rothamsted, with a moderate dressing of nitrate of sodium
to barley, together with a liberal supply of ash constitu-
ents, about 60 per cent, of the nitrogen has been on an
average recovered in the increased produce. A much larger
proportion is recovered in good seasons. With mangels,
manured in a similar manner, about 62 per cent, of the
nitrogen in the nitrate of sodium has been, on an average,
recovered in the increased produce of roots obtained, the
nitrogen in the leaves being not reckoned, as they are
returned to the soil. In the absence of a full supply of
ash constituents the amount of nitrogen recovered in the
crop is seriously diminished. Ammonium salts, and rape-
cake, applied as manures, have yielded a smaller return
than nitrate of sodium.

Most soluble and active manures produce their prin-
cipal effect at once, and are of little benefit to subsequent
crops. Ammonium salts or nitrates give all their effect
in the first year. Sparingly soluble manures, and those
which must suffer decomposition in the soil before they
are of service to the plant, as farmyard manure and bones,
will on the contrary continue to produce an effect over
many years. Farmers have a prejudice in favour of the
latter class of manures, but it is clear that the quickest
return for capital invested is afforded by the former class.
In the case of farmyard manure, applied annually on the

46 THE CHEMISTRY OP THE PAEM.

heavy land at Kothamsted to wheat and barley, only about
10 to 15 per cent, of the nitrogen has been recovered in
the increase ; but the effect on the barley has continued
for many years after the application of the manure ceased.
It is evident that a small quantity of an active manure
will accomplish the same work as a large quantity of one
less active.

The residues of phosphatic and potassic manures are
available for subsequent crops, but are distinctly less
effective than fresh applications of the same manures.

CHAPTER IV.

CROPS.

The dry matter, nitrogen, and ash constituents, in average crops. Cereal
Crops. — Characteristic composition — Mode of feeding — Most suitable
manuring. Meadow Hay. — Characteristic composition — Demand for
ash constituents — Influence of manures on quantity and quality —
Pastures especially adapted for obtaining nitrogen from the atmo-
sphere. Leguminous Crops — Characteristic composition — Special
source of nitrogen — Clover-sickness. Root Crops. — Characteristic
composition — Differences in the nutrition of turnips, mangels, and
potatos. Forest Growth. — Large production of dry matter for small
consumption of ash constituents and nitrogen. Adaptation of
Manures to Crops. — The feeding power of each crop must be taken
into account. —Economic distribution of manure in a rotation — The
practical value of manures only known by experiments on each farm.
Influence of Climate and Season. — Effect of excess or deficiency of
water and heat — Influence of preceding Winter. Crop Residues.—
Their action — Differences between different crops. Weeds. — Their
beneficial and injurious actions.

To understand the chemistry of crops we must first
inquire as to their composition. The following table gives
the average composition of ordinary farm crops, and of
the annual produce of three descriptions of forest. The
quantities of carbon, hydrogen, and oxygen present are
omitted, also some of the smaller ash constituents. By
"pure ash3' is understood the ash minus sand, charcoal,
and carbonic acid.

The composition of grain is tolerably constant ; but the
composition of straw, leaves, roots, and tubers, will vary
very considerably according to the character of the soil,
the manuring, and the season. The composition of

48

THE CHEMISTEY OF THE FARM.

•twins

ro ^ *?

os

oo oo

TH CO
rH 0

CD
OO
CD

05 rH

CO

0

o

•

os

9

»-H 03

o cb

co

,^0

jSX

t

o co
o cb

TH

rH

0 i-H

0 CO

CO

cb

CO

o \

•

rH

TH

CO

co

TH

oo

os

CO

TH CO

0

•ppv

o3 ^ ^

rH

co

rH

S

O -^

cb cb

TH

rH

03

H

oo

1*

p

-30

op cp
co cb

os

CO

^**

Jcbcb

b-

O OS

CD

CDTH

t^

rH

rH

CO

^S

os

os

COO

00

CO

•

rH

TH

%

•^

•22

43 TH OO

os

cop

rHOO

CO

os

oo oo

co

TH

0

•

TH

os

OS CO

co cb

(M

CO

OS
CO

••epos

WCOO
j2 0 CO

co

TH OS
rH CO

p

00 CO
OrH

rH
0

o \

CO

05

0

OrH

cp

•**.

.coo

00

0005

t^

TH O

TH

ooo

co

os

rH

CO 00

,_,

^§05 05

oo

CO

05 0
CO

0

co

01 co

CD
rf

^8

^

§

CO

oo

rH <N
CO rH

co

unqclpig

cr° b- iH
£ CO 0

oo
b-

co cb

cb

co oo

cb rH

00

00

os
rH

os
1

rH OS

cp

OS

•»*™

W COO

r^CO TH

00

S3

9

oo b-

CO TH

§

83

co
rH

KS

1

•qs-e 8and

j» o co

£

CO TH

g

iH O

03
TH

CO 05

co os

CO

TH

CO

oo

OO OS

o os

rH

Weight of crop.

ft

gff

co
oo

rHOO

|

co o

OO
t—

OS

tb-
oo
TH TH"

1

CO

00^

CO

co"

co oo

i— 1

CO

co"

— rHCO

"*

THCO

CO

1

THCO

CO

At
Harvest.

§00
- „ "3
,000-*

oo

05

O b-

00 -H
OrH

i

SO
co
oo oo

0

g§

CD CO

OO

oo

00

o

CO
CO

o

oo

O 0
CO rH
03 CO

g

i

02

JB

RED CLOVER HAY, 2 tons

BEANS, grain, 30 bushels
„ straw „

Total crop .

WHEAT, grain, 30 bushel
„ straw . . .

Total crop

BARLEY, grain, 40 bushe
straw . . . .

Total crop

OATS, grain, 45 bushels
„ straw ....

Total crop

MAIZE, grain, 30 bushels
„ stalks, etc. . . .

Total crop

MEADOW HAY, 1£ ton .

CEOPS.

49

'PPV
otjotjdsoqj

"Bpog

At
Harvest.

£ COiO

.rH l>-

383

!coco
rH ^H
CO rH

. <-£? rH l>"
00 CO CO ^O

^ rH \O CO

-
«* •»

rH CO

CO CO

oo co

S58

CO

tons
„

crop

t,
f

SWED
i)

0005

S, ro
leaf

MANG
„

cp I co os

CO I rH05

«O CO CC
CO rH6o

POTAT rs,

BEEC wood
„ leaf litter

rH i£>

OrH

CO CO
CO rH

O rH rH
CO CO rH

FIR, wood
leaf litte

SPRUC
„

000

05 CO

cot>.

OH

rHiO
CO rH
00 00

co'co"

. .

litter .

produce

tal

NE, w

l

To

OTCH
„

SC

50 THE CHEMISTRY OF THE FARM.

iodder and root crops is thus especially liable to varia-
tion. This subject is discussed on page 92,

Cereal Crops. — These contain much less nitrogen than
either leguminous or root crops ; about three-quarters
of the nitrogen is in the corn, and only one quarter in
the straw. The amount of phosphoric acid is not very
different from that found in other crops ; this ingredient
is, in fact, the most constant in quantity of all the con-
stituents of crops. The phosphoric acid is chiefly con-
centrated in the corn. Potash and lime are present in
much smaller quantity than in other crops; they are
chiefly found in the straw.

The presence of a large amount of silica is character-
istic of the cereal crops; they possess apparently a
capacity for feeding on silicates not enjoyed by other
crops. The base of the silicate is made use of by the
plant, while the silica itself is excreted upon the surface
of the leaves and straw. It has been shown that silica
is by no means essential for the growth of cereals : they
take it up freely, but can also do without it.

Owing to their small demands upon the soil, and
possibly also to their capacity for assimilating silicates,
cereal crops will for a long time continue to yield a
moderate produce upon exhausted unmanured land ; a
fact of great importance to the human race.

The autumn-sown cereals (wheat and rye) have both
deeper roots and a longer period of growth than the
spring-sown cereals (barley and oats), and are conse-
quently better able than the latter to supply themselves
with the necessary ash constituents from the soil. Barley
possesses a considerable development of root near the

MEADOW HAY. 51

surface and is apparently more capable of obtaining
nitrogen from the soil than wheat. Maize has a later
period of growth than the cereals already mentioned and
will thus have a greater command of the nitrates pro-
duced in summer. Owing probably to this fact it is a
crop less dependent on nitrogenous manure than wheat.

Cereal crops derive their nitrogen almost exclusively
from nitrates ; the form of organic combination in which
the great bulk of the nitrogen is present in the soil is not
suited for their assimilation. Notwithstanding, there-
fore, the small amount of nitrogen contained in cereal
crops, they rank among those most benefited by nitro-
genous manures. Phosphates, though generally of little
use by themselves, are also beneficial (especially in the
case of spring-sown crops) when applied with nitrogen-
ous manure. A nitrogenous guano, or a spring dressing
of nitrate of sodium and phosphatic slag, or sulphate of
ammonia with superphosphate, is generally the most
effective manuring for a cereal crop. When malting
barley of high quality is to be produced the supply of
nitrogenous manure must be carefully limited. Nitrate
of sodium always gives a larger return in straw than
sulphate of ammonium.

Meadow-Hay.— The grasses which form the main bulk
of hay belong to the same family of plants as the cereal
crops; the seed, however, in grass bears such a small
proportion to the stem and leaf that meadow hay may be
regarded as a straw crop. In accordance with this char-
acter hay is found to contain a much larger proportion
of potash and lime than cereal crops, and a much smaller
amount of phosphoric acid.

52 THE CHEMISTRY OP THE FARM.

The roots of grass being far shorter than those of the
cereals are less able to collect ash constituents from the
soil ; if, therefore, grass is mown for hay, manures con-
taining potash, lime, and phosphoric acid will generally
be required. Like the cereal crops, grass is greatly
increased in luxuriance by the application of soluble
nitrogenous manures.

Farmyard manure, or the feeding of cake, corn, or
roots on the land, is the most appropriate manuring for
permanent pasture, if a high quality as well as quantity
of produce is desired. Large crops of hay may be
obtained by manuring with nitrate of sodium, together
with kainite and superphosphate ; but a continuance of
such treatment promotes a coarse herbage.

The natural clovers of a meadow are destroyed by the
continued application of highly nitrogenous manures, a
hay consisting almost exclusively of grass being pro-
duced. The clovers are developed by the application of
manures supplying potash or lime without nitrogen. The
effect of pasturing is to check the development of coarse
herbage, and to promote the growth of the finer grasses
and clover.

The perennial character of meadow herbage, which
usually includes a variety of leguminous plants, presents
favourable conditions for the collection of nitrogen from
the atmosphere : see pp. 65,66.

Leguminous Crops.— Some of these are grain crops,
as beans and peas ; others are fodder crops, as red clover,
sainfoin and lucerne. A striking characteristic of all
these crops is the large amount of nitrogen which they
contain, the quantity being about twice as great as that

LEGUMINOUS CROPS. 53

found in cereal crops of the same weight. The quantity
of potash and lime in leguminous crops is also very large.
The relative proportion of these two bases varies much
in crops grown on different soils ; upon a calcareous soil
lime will preponderate in the crop, but on a clay soil
potash. The lime is found chiefly in the leaf. Silica is
nearly absent in leguminous crops.

The amount of nitrogen collected by leguminous
crops is very remarkable. A good crop of red clover,
when cut for hay, removes a large quantity of nitrogen
from the land, but it nevertheless leaves the surface soil
actually richer in nitrogen than it was before, from the
residue of roots and stubble left in the soil. From
whence is this large quantity of nitrogen obtained ? It
must be procured either from the subsoil or the atmo-
sphere. The question is made more puzzling by the fact
that nitrogenous manures generally produce but little
effect upon leguminous crops. It seems now quite cer-
tain that leguminous crops possess in their root tubercles
an apparatus capable of bringing the nitrogen of the
atmosphere into combination (see p. 10). The special
agent residing in these tubercles is a micro-organism
derived from the soil. In the case of a poor soil the pre-
sence or absence of the necessary organism in the soil
may determine its fertility or barrenness for a leguminous
plant. It must, however, be recollected that, apart from
the tubercles, leguminous plants are nourished in an
ordinary way through their root-hairs, and that a deeply-
rooted plant, like red clover or lucerne, obtains consider-
able food supplies from the subsoil.

Except in the case of extraordinary rich soils, land
loses the power of growing most leguminous plants by

54 THE CHEMISTRY OF THE FARM.

repeated cropping with them, and is said to be " clover
sick" or "bean sick." The origin of this barrenness
has not yet been satisfactorily explained ; it is generally
intensified by an attack from insects on the weakened
plant. No means of remedying this condition is known
save by the growth of other crops for a series of years.

Potash manures have generally a very beneficial effect
upon leguminous crops; they fail, however, to cure
clover sickness. Farmyard manure, phosphates, gypsum
and lime are also serviceable.

Root Crops.— All these crops contain a large amount
both of nitrogen and ash constituents ; among the latter
potash greatly preponderates. Turnips contain more
sulphur than any other farm crop.

Turnips and swedes draw their food chiefly from the
surface soil. Their power of taking up nitrogen from the
soil is distinctly greater than that of the cereal crops.
Turnips are also well able to supply themselves with potash
when growing in a fertile soil, but they have singularly
little power of appropriating the combined phosphoric
acid of the soil. On exhausted land it is generally im-
possible to obtain a crop without a supply of phosphates.

Mangels have far deeper roots than turnips, and also a
longer period of growth. They have a great capacity for
drawing food from the soil, including both nitrogen,
potash, and phosphoric acid. When carted off the land
they are probably the most exhaustive crop that a farmer
can grow. As mangels have not the same difficulty that
turnips have of attacking the combined phosphoric acid
oi: the soil, phosphatic manures are, in their case, of much
less importance. Nitrate of sodium, when applied alone

FOEEST GROWTH. 55

to mangels, generally produces a great effect on the crop ;
this is not the case with turnips, which require phosphates
as well as nitrogen in their manure.

As both turnips and mangels consume extremely large
amounts of plant food, a liberal general manuring with
fsr*myard manure is in most cases essential for the pro-
duction of a full crop ; but the special characteristic of
the manure for turnips should be phosphatic, and of that
for mangels nitrogenous. With an abundant supply of
nitrogenous manure the proportion of leaf is increased,
and the maturity of the root delayed. A heavily manured
crop should be sown early. Late-sown crops of turnips
or swedes should receive a smaller proportion of nitrogen,
and a larger proportion of phosphates in their manure.

When beetroot is grown for sugar it is essential to
produce small roots; heavy manuring is therefore
avoided, and the roots grown near together.

Potatos are surface feeders, and require a liberal
general manuring to ensure an abundant crop.

As both root crops and potatos require large supplies
of potash, kainite will be found of service on land naturally
poor in that ingredient. It will be chiefly required when
the crops are raised with artificial manures only, as farm-
yard manure will always supply a considerable amount of
potash.

Forest Growth.— The figures given in the table re-
present the composition of the produce of beech, spruce
fir, and Scotch pine forests felled for timber, and are the
results of extensive investigations made in Bavaria.

The amount of dry matter in the annual forest growth
is in excess of that yielded by any of the cultivated crops

56 THE CHEMISTRY OF THE FARM.

given in the table, excepting mangels. This large pro-
duce is obtained by a very small consumption of soil food ;
the amounts of potash and phosphoric acid required are
especially far less than in the case of any farm crop.
The greater part both of the ash constituents and nitrogen
is found in the fallen leaves; if these are left undis-
turbed, and allowed to manure the ground, the require-
ments of the forest become extremely small, far smaller
than in ordinary farm culture. It appears that about
3000 Ibs. of perfectly dry pine timber are produced with
a consumption of only 2J Ibs. of potash, and 1 Ib. of
phosphoric acid per acre per annum : with beech timber
the quantities required are rather larger. The amount of
nitrogen in timber is very small ; the annual growth of
beech wood contains on an average about 10 Ibs. per acre.
The amount in the leaves and seeds is much more con-
siderable. Forest trees do not produce seed till they are
of mature age ; the seed is formed at the expense of
matter previously stored in the tree. When the litter is
not removed, the surface soil will gain considerably in
organic matter (containing both ash constituents and
nitrogen) during the earlier years of forest growth, and
thus greatly improve in value.

Adaptation of Manures to Crops.— The true economy
of manure can be understood only when we are acquainted
with the special characters of the crops we cultivate.
The composition of a crop is no sufficient guide to the
character of the manure appropriate to it, even when we
possess in addition the composition of the soil on which
it is to be grown. It is not only the materials required
to form a crop, but the power of the crop to assimilate

ADAPTATION OF MANURES TO CKOPS, 57

these materials, which must form the basis of our judg-
ment. This fact has been much overlooked by many
scientific writers, who have counselled farmers to manure
their land in every case with all the constituents required
by the crop, a proceeding both impracticable and un-
necessary. In the case of a barren sand it may indeed
be requisite to supply all the constituents of plant food
before a crop can be grown, but such a case is far removed
from the circumstances of ordinary agriculture.

When land is in a fertile condition the total amount
of plant food available for crops is very considerable, and
luxuriant growth may be obtained by supplementing the
stores of the soil with the few particular elements of food
which the crop it is wished to grow has most difficulty in
obtaining. Thus, in a large majority of cases, a dressing
of nitrate of sodium and phosphates will ensure a full
crop of wheat, barley, or oats, and in many cases nitrate
of sodium alone will prove very effective. These cereal
crops generally find the supply of nitrates in the soil
insufficient for their full growth, and the supply of
phosphates more or less inadequate ; but in a majority of
cases they are well able to obtain a sufficient supply of
potash and other essential elements of plant-food. We
are thus able, by supplying one or two constituents of the
crop, to obtain a luxuriant harvest. In the same way
nitrate of sodium employed alone will, in most cases,
produce a large crop of mangels ; superphosphate alone,
a large crop of turnips ; while potassium salts alone may
be strikingly effective with pasture and clovers.

This special manuring for each crop is no strain on the
capabilities of the soil if a rotation of crops be followed.
If superphosphate is applied for the turnips, potassium

58 THE CHEMISTRY OP THE FAEM.

salts for the seeds, and a nitrogenous manure for the cereal
crops, the more important elements of plant food con-
tained in the soil will not be diminished at the end of the
rotation. At the same time the most economic result will
have been obtained from the manures employed, for each
manure will have been supplied to that particular crop
with which it yields the most remunerative result.

It is doubtless possible by means of rotations manured
on the above principles to farm successfully with the sale
of all the crops produced, and without the use of farm-
yard manure ; this is possible at least so long as artificial
manures can be obtained at a low price. In the majority
of cases, however, the special manuring will only be
required to supplement the general manuring by farmyard
manure. Under these circumstances it would seem best,
from a chemical point of view, to apply the farmyard
manure to those crops which most require potash, or
which stand most in need of a general manuring ; such
crops would be pasture, artificial grasses, turnips and
potatos.

As the whole object of artificial manuring is to supple-
ment the deficiencies of the soil, it is highly desirable
that a farmer should ascertain by trials in the field what
is the actual amount of increase which he obtains from
the application of the manures he purchases. A few
carefully made experiments will teach him what his land
and crops are really in need of. Should he add super-
phosphate with the nitrate of sodium for his wheat ?
What dressing of the nitrate is most economical ? Is
superphosphate alone sufficient for his turnip crop, or
should guano or nitrate be employed as well ? What is
the smallest quantity of superphosphate sufficient for the

INFLUENCE OF CLIMATE AND SEASON. 59

crop ? Will it pay to use potassium salts for his seeds,
his pasture, or his potato crop ? These and many other
questions can only be answered by trials on his own
fields. On the farmer's knowledge of such facts will de-
pend the economy with which he is able to use purchased
manures, which are too often wastefully employed.

Influence of Climate and Season.— The influence of
weather upon crops is far greater than the influence of
manure.

As a plant contains water as its largest constituent,
and as the whole of the plant food obtained from the soil
is taken up through the medium of water, while the
amount of water daily lost by the plant through evapora-
tion is very large, the necessity of a large supply of water
in the soil during the growing period of a crop is very
evident. On the other hand, an excess of water in the
soil prevents root development, and causes a loss of
nitrates and other soluble plant foods in the drainage
water. Deeply-rooted crops, as wheat, red clover,
lucerne, sainfoin, and mangel, are those best fitted to
resist drought ; while shallow-rooted crops, as grass and
turnips, are those which suffer most from it.

We have already seen that carbon, which forms the
largest ingredient of all vegetable substances, is obtained
by plants from the atmosphere under the influence of
light, and that a certain temperature is necessary for this
assimilation of carbon and for the other chemical pro-
cesses which proceed in a growing plant • a sufficient
supply of light and heat is therefore required for
the production of a crop. In a season of deficient light
and heat the harvest is always late, growth having taken

60 THE CHEMISTRY OF THE FARM.

place more slowly than in an average season. In the case
of extremely cold and cloudy summers the whole season
may be too short for maturing the crop, and the seed in
consequence may never be fully ripened. Early sowing
is generally advisable, as a longer period for growth is
thus afforded to the crop.

As the character of the season determines the degree
of maturity reached at harvest, it has a great influence
both on the composition and quality of the crop. A
fine malting barley, rich in starch, can only be produced
in a fine season; any imperfect ripening, produced either
by cold, wet weather, or by the premature drying of the
grain during severe drought, will result in the production
of grain poor in starch and relatively rich in nitrogenous
matter. The effect of season on the composition of a crop
will be found further discussed on pp. 14, and 92-94.

Each crop requires more or less a different climate
for its perfect development ; a knowledge of the kind of
climate best suited to each crop is of great service in
selecting crops for any particular district. Thus wheat
requires hot and dry weather for its ripening period,
while oats will ripen in a moist atmosphere. Mangels
require heat, and can resist drought, while turnips de-
velop best in a cool, moist air. Oats and turnips thus
best suit the Scotch climate, while wheat and mangels
are better fitted for the south-east of England.

The soil best furnished with plant food is the one
which will yield the best results in adverse seasons, the
crop having a greater amount of vitality and being able
to turn to the best advantage the short periods of favour-
able weather that may occur. Poor soils yield their best
results in seasons of slow but continued growth, the crop

CEOP RESIDUES. 61

having a longer time to collect the scanty supply of food
which the soil contains. In hot seasons, with an early
harvest, only soils well supplied with food can produce
full crops.

The character of the winter has a considerable influ-
ence on that of the following season. In a wet winter
the soil may lose nitrates by drainage to a large extent.
Root development will also be prevented by excessive
wet. After such a winter the wheat crop generally is in
a backward condition, and finds itself in an impoverished
soil. In climates having a very severe winter the nitrates
are preserved from loss by the frozen condition of the
soil. In sprin^ the melted snow is removed mostly by
surface drainage, the soil beneath being still frozen ; the
water produced by the snow consequently does not remove
the soluble matter of the soil.

Crop Residues.— The portion of the crop left in the
soil after harvest serves most important functions ; on
this residue (apart from actual applications of organic
manure) the maintenance of the humus, and consequently
of the nitrogen of the soil, depends. The quantity of
residue left by different crops is very different. From a
crop of turnips, mangels, or potatos, practically no root
residue remains in the soil ; the residue, in the case of
root crops, is limited to the leaves which may remain un-
eaten by the stock. The residue of roots and stubble left
by an annual cereal crop is rather considerable, but poor
in nitrogen. The residues from deeply-rooted crops,
which have long held possession of the soil, as sainfoin
and red clover, but especially lucerne, are very large,
amounting to many tons of dry matter, and containing

62 THE CHEMISTRY OP THE FARM.

100 — 200 Ibs., or even more, of nitrogen per acre. In
the case of permanent pasture the effect of long-continued
crop residues is strikingly manifest, the surface soil con-
taining twice as much nitrogen, and more than twice as
much carbon, as ordinary arable land. In the case of
pine forests, the accumulated residues of dead leaves,
<£c., are also very large : chiefly by their means bare rock
is often transformed into fertile soil. It is obvious that
the more luxuriant a crop the greater will be the crop
residue : a series of good crops thus tends to enrich the
soil with nitrogenous humus, while under a series of bad
crops the soil will diminish in fertility.

Weeds.— The weeds of a farm form a natural crop ;
their influence is at times beneficial and at times injurious
to the farmer. That some vegetation should grow on the
land in the absence of a regular crop is most desirable.
The rapid growth of weeds after harvest will greatly
diminish the loss of nitrogen by drainage and be of use
in other ways as a green crop. When the weeds are
ploughed-in in the spring the valuable matter stored up
by them again becomes available as plant food. On the
other hand3 it is obvious that a crop will have little chance
of obtaining plant food if it has to compete with growing
weeds which have obtained earlier possession of the soil.
The best plan is apparently to destroy weeds, and to ob-
tain the important benefits they yield by a judicious use
of green crops, sown so as to occupy the land after har-
vest.

CHAPTER Y.

ROTATION OP CROPS.

The aim of rotations. Bare Fallow.— Effects on the soil — Production of
nitrates. Green Crops.— Effects of feeding on the land, or ploughing
in— Gain of nitrogen to the soil by laying down land in pasture,
or in leguminous crops — Advantages of green manuring. Dis-
tinctive characteristics of Crops.— Differences in periods of growth,
range of roots, powers of assimilation, and quantity of food
demanded. Losses to the land during rotation.— Losses in an assumed
four-course rotation, how replaced — Losses of nitrates, how prevent-
ed— Gain of nitrogen from the atmosphere — Economical rotations —
Sale of produce other than corn and meat.

IT is by no means impossible to grow the same crop
with success year after year on the same land ; ordinary
pasture is indeed an example of continuous cropping.
The Rothamsted experiments show that excellent crops of
wheat, barley, and mangel may be continuously obtained
if appropriate manure is annually applied, and the land
kept free from weeds. A rotation of crops is resorted to
in ordinary practice in consequence of the facilities
which such a plan affords for cleaning the land, and from
the greater economy of manure which results from this
practice. One of the principal aims of a rotation is to
bring the land from time to time into a condition suitable
for growing cereal crops ; this suitable condition consists
mainly in the accumulation of nitrogenous plant food in
the surface soil.

Bare Fallow.— A bare fallow is one of the oldest modes
of preparing soil for wheat. The soil is ploughed, and

64 THE CHEMISTRY OF THE FARM.

exposed a whole year to atmospheric influences, and finally
sown with wheat. In the case of a clay soil this treat-
ment would probably lead to the following results : — 1. An
improvement in the mechanical texture of the soil. 2.
The disintegration of some of the mineral silicates,
whereby potash and other necessary ash constituents of
plants would be liberated and made available for vegeta-
tion. 3. The absorption of ammonia from the atmosphere
by the soil. 4. The receipt of both ammonia and nitric
acid from the air in the form of rain. 5. The oxidation
of ammonia, and of the vegetable and animal remains in
the soil, carbonic and nitric acids being produced.

The production of nitric acid is probably the most
important result of a bare fallow. In ordinary farm soils
at Rothamsted left as bare fallow, there has been found
.at the end of the summer 34 — 55 Ibs. of nitrogen per acre
in the form of nitric acid in the first 20 inches from the
surface, the quantity depending on the richness of the soil
in nitrogenous matter and the character of the season.
The whole amount of nitrates produced during the 15
months that the land remains without a crop has been
estimated at not less than 80 Ibs. of nitrogen per acre for
the fields under ordinary cultivation at Rothamsted. Sup-
posing the season of fallow, and the following winter, are
fairly dry, this increase in the available nitrogenous food
will probably enable the soil to produce twice as much
wheat as it could do without a fallow. If, however, the
soil is exposed to heavy rain, the nitrates produced will be
more or less washed out, and the benefit of the fallow
greatly diminished. Amass of soil at Rothamsted, 5 feet
deep, left for 20 years uncultivated, unmanured, and kept
free from weeds, has lost by drainage in the last 13 years

ADVANTAGES OF GEEEN CROPS. 65

from 28 to 47 Ibs. of nitrogen in the form of nitrates per
annum. Bare fallow can be used with advantage only on
clay soils, and in a tolerably dry climate ; under other
circumstances the practice must result in a serious loss of
soil nitrogen.

Green Crops.— The most usual plan for bringing land
into condition for the growth of cereals is the cultivation
of green crops. These may be ploughed in, forming what
is termed green manuring ; or consumed on the land by
the farm stock ; or the crop may be removed, consumed
in cattle-sheds or in the farmyard, and the resulting
manure brought on to the land. The principle in every
case is that the constituents of the crop shall be returned
to the soil.

Let us suppose that land is laid down with grass and
clover seeds, and after two or three years is ploughed up
and a cereal crop taken. Whilst the land is continuously
covered by vegetation the loss of nitric acid by drainage
will be reduced to a minimum. If the grass is fed off on
the land the surface soil will at the end of the three years
be considerably enriched both with ash constituents and
nitrogen. The former have been collected from the subsoil
by the roots of the crop and returned to the surface soil
as animal manure. The latter includes the accumulated
receipts from the atmosphere and subsoil during the three
years, minus the quantity lost by drainage and that assimi-
lated by the animals. The accumulated nitrogen will be
chiefly in the form of grass roots, stems, and humus.
When such land is ploughed up the vegetable matter and
humus are oxidised, and gradually yield their nitrogen as
nitric acid.

6

66 THE CHEMISTEY OP THE FAEM.

Such a mode of cropping has several advantages over
a bare fallow : — 1. The land is turned to profitable use,
food being produced for the farm stock. 2. Both ash
constituents and nitrates are collected from the subsoil
and brought to the surface. 3. Nitrogen is acquired from
the atmosphere by the crop, as well as by the soil. This
is especially true if leguminous plants are grown. 4. The
nitrogen collected is kept in an insoluble form, as vege-
table matter, and consequently cannot be washed away,
but accumulates in the surface soil to a greater extent
than is possible in a bare fallow. 5. Humus is produced
in considerable quantity, the beneficial actions of which
have already been noticed.

As an illustration of the accumulation of nitrogen in
the surface soil when land is laid down permanently in
pasture, we may refer to the arable land laid down to
grass at Rothamsted, which gained nitrogen during 33
years at the rate of about 52 Ibs. per acre per annum.
Taking into account the quantity of hay removed, the
greater part of this increase of nitrogen in the soil could
not be accounted for by the quantity applied as manure ;
it was probably to a considerable extent derived from the
atmosphere.

Leguminous crops, as already mentioned, have a
special power of acquiring nitrogen from the atmosphere
by means of their root tubercles, and are hence of the
greatest value in a rotation. The accumulation of nitrogen
in the surface soil in the form of roots, stubble, and de-
cayed vegetable matter, is in the case of a good crop of
clover so considerable that the whole of the above ground
growth may be removed as hay, and the land yet remain
greatly enriched with nitrogen and in an excellent COD-

DISTINCTIVE CHARACTERISTICS OF CHOI'S. 07

dition for producing a crop of wheat. The growth of
leguminous crops is the most important means which
a farmer possesses for enriching his arable land with
nitrooen.

The ploughing in of green crops has some advantages
over the feeding of crops on the land. By this mode of
proceeding the whole of the crop is returned to the soil,
whereas in feeding a small part of the nitrogen and ash
constituents is retained by the animal. The characteristic
advantage of green manuring lies, however, in the large
amount of humus which the soil acquires. All the carbon
which the crop has obtained from the atmosphere is in
this case incorporated with the soil, instead of being con-
sumed by the animal. Green manuring is thus especially
adapted for light sandy soils which need humus to in-
crease their retentive power. It is employed with great
advantage to fertilise barren soils in hot climates.

Having glanced at the general advantages to be de-
rived from alternating green crops with cereals, we will
consider next the characteristics of different crops which
specially fit them to succeed or prepare for each other.

Distinctive Characteristics of Crops.— Differences in
their periods of growth occasion a marked distinction in
the relation of different crops to soil nitrogen. Thus the
fact that the active growth of the cereals commences in
spring, and concludes at their time of blooming towards
the end of June, places these crops at a disadvantage as
to the supply of nitrates from the soil. The autumn aud
winter rains have frequently washed out the greater part
of the nitrates contained in the soil before the growth of
the cereal crop commences, and nitrification in the soil hus

68 THE CHEMISTRY OF THE FARM.

not long recommenced its activity in the summer months
when the crop becomes too mature to appropriate fresh
supplies of nitrogen. Continuous wheat cropping thus
results in a gradual impoverishment of soil nitrogen by
autumn and winter drainage, over and above the nitrogen
actually removed in the crops, and thus necessitates a
considerable application of nitrogenous manure if fertility
is to be maintained. Maize, with its later period of growth,
is better able to supply itself with nitrogen from the soil.

A root crop sown in early summer, on the other hand,
has at its disposal all the nitrates that would be available
for wheat or barley, and in addition the large supply of
nitrates formed in the soil during summer and early
autumn. A great part of the nitrates which would be
lost by drainage during cereal cultivation is thus assimi-
lated and retained by a root crop, and such crops are
found to stand in less need of nitrogenous manure than
cereals. By consuming the roots on the land the nitrates
collected by the crop are returned to the soil in the form
of animal manure, and the land thus prepared to carry a
cereal crop. Similar remarks might be made respecting
other green crops whose active growth extends into the
autumn.*

Another important difference between crops lies in
their range of roots. Deeply-rooted crops, as lucerne^
sainfoin, red clover, rape, and mangel, and among the
cereals wheat and rye, are to a considerable extent sub-
soil feeders, and have a greater power of obtaining ash
constituents from the soil than shallow-rooted crops, as
white clover, potatos, turnips, and barley. In accordance

* The writer is indebted to Sir J. B. Lawes for the important ideas
contained in the two preceding paragraphs.

DISTINCTIVE CHARACTERISTICS OF CEOPS. 69

with this we find that superphosphate is a very effective
manure for the last three crops, but is much less required
by such crops as mangel or wheat. By growing deeply-
rooted crops as part of a rotation the subsoil is made to
contribute to the general fertility. Shallow-rooted crops,
on the other hand, have generally a special faculty for
appropriating food accumulated at the surface, and are
often of great use in this respect, as when barley is made
to follow turnips fed off on the land.

Yery little is definitely known as to the different
capacity of different crops for assimilating various forms
of plant food, but there can be no doubt that this forms
one of the most important distinctions between various
crops, and is one reason of the economy of a rotation.
A very plainly marked distinction as to mode of feeding
is afforded by the behaviour of various crops towards
silica. Graminaceous crops, as the cereals and grasses,
are apparently capable of assimilating certain of the
silicates contained in the soil, while other crops exhibit
no such capacity. In such a case it is easy to imagine
that an alternation of cereals with crops of a different
description may be for the benefit of both, each drawing
to some extent upon distinct supplies of food. Again,
leguminous crops are clearly able to assimilate nitrogen
to a far greater extent than cereals, and from a different
source. If crops of winter beans and winter wheat are
grown on similar unmanured land the bean crop will
generally contain twice as much nitrogen as the wheat.
The land is not, however, impoverished for wheat by the
growth of beans, for wheat after beans will be a far better
crop than wheat after wheat, thus affording a striking
example of the advantages of a rotation.

70 THE CHEMISTRY OP THE FARM.

The quantities of plant food required by different crops
are given in the table on pp. 48 — 49; these also furnish
reasons for the alternation of crops. It will be seen, for
instance, that the cereals require but little potash and
lime, while root crops, beans, and clover demand a large
supply ; it is obvious, therefore, that the resources of the
soil are husbanded by growing these two classes of crops
in alternation, the greater demand for. potash and lime
thus falling every alternate year.

The net result of a judicious alternation of crops, in
which the special characteristics of each are turned to good
account, is the production of a maximum total yield of
produce with a minimum amount of manure.

Losses to the Land during Rotation.— The table
showing the composition of ordinary farm crops will
supply the requisite information as to the loss which a
farm may suffer by the sale of individual crops. We will
now consider briefly the losses during a rotation.

The conservation of plant food on a farm is generally
effected by confining the exports to corn and meat, the
rest of the produce being consumed on the farm, and the
manure returned to the land. Let us assume that a farm
is managed on the four-course system, and that the
average crops obtained per acre are — swedes, 14 tons;
barley, 40 bushels ; seeds (half clover, half grass), 3 tons
of hay, and wheat, 30 bushels. Further, that nothing is
sold save corn and meat ; that 2 bushels both of wheat
and barley are returned to the land as seed ; that 700 Ibs.
of linseed cake are fed with each acre of swedes ; that
1 10 Ibs. of oats are purchased per acre per annum for the
horses. Finally, that half a ton of straw is fed per acre

LOSSES DURING ROTATION.

71

in the course of the rotation, and the rest used as litter.
If the whole of the manure is returned without loss to
the land, the quantities of nitrogen, phosphoric acid, and
potash lost during the four years' rotation, as excess
of exports over imports, will be as follows : —

ESTIMATED LOSSES PER ACRE DURING A FOUR-COURSE
ROTATION BY SALE OF CORN AND MEAT.*

Nitrogen.

Phosphoric
Acid.

Potash.

By feeding swedes, 14 tons
By sale of barley, 38 bushels
By feeding seeds, 3 tons hay
By sale of wheat, 28 bushels
By feeding straw, £ ton

Ibs.
6-8
32-3
10-9
,0-8
1-2

Ibs.
4-03
14-35
6-51
13-35
0-72

Ibs.
0-51
9-60
0-82
9-05
0-09

Deduct manure from 440 Ibs. oats,
and 700 Ibs. oilcake .

82-0
36-5

38-96
12-74

2007
10-70

Total loss in 4 years .

45'5

26-22

9'37

Average loss each year

11-4

656

i'34

The loss of potash is extremely small, and may gener-
ally be quite disregarded. If, however, no cake is used,
and the land is poor in potash, the loss might be replaced
by the use of ] i cwt. of kainite for the seeds. The loss
of potash will be greater than we have assumed if urine
has been lost in the stables, or if the farmyard manure
has suffered by rain and drainage.

The loss of phosphoric acid would be replaced, even

* The figures given in this table differ from those in former editions,
more complete data being now available. It is now assumed that
the crops are consumed by sheep and cattle of all ages, and not
simply by fattening stock.

72 THE CHEMISTEY OF THE FARM.

if no cake were employed, by the use of 2 cwts. of super-
phosphate for the swedes.

The loss of nitrogen is »een to be more considerable
than the loss of phosphoric acid or potash. The figures
given are also certainly below the truth, as they take no
account either of loss of nitrogen in the manure, or of the
nitrates lost to the soil by drainage.

If the losses of nitrogen in the stable and the manure
heap amount to one half of the original nitrogen in the
manure (a case which is by no means impossible), the
annual loss of nitrogen will be raised to 42 Ibs. per
acre.

The average annual loss of nitrogen as nitrates by
drainage from the soil (calculated from the composition
of uncontaminated spring and well waters) is in England
not less than 7 ibs. per acre. On arable land the loss,
especially in wet seasons, will riiuch exceed this figure.
Much may be done by the farmer to diminish this loss.
The early sowing of mustard, turnips, rape, or rye on
stubbles which are to be followed by a spring- sown crop
is most desirable; the green crops thus obtained to be
fed, or ploughed in, before the spring sowing. In the
case of a bare fallow it has been found advantageous to
plant mustard early in August, and plough the crop in in
October before wheat sowing. By such methods the
nitrogen of the nitrates is converted into vegetable matter,
and preserved from loss by drainage.

Against the losses of nitrogen we have enumerated we
have to place the amount annually supplied to the land
by the rainfall, say 4 — 5 Ibs. per acre; and also the un-
known and more considerable quantity absorbed as
ammonia from the atmosphere by soil and plant. Of

LOSSES DURING ROTATION. 73

much greater importance is the supply of nitrogen ob-
tained by the cultivation of leguminous crops. Where
such crops can be successfully grown, and are consumed
upon the farm, there should be little fear of a deteriora-
tion in the nitrogenous contents of the soil under the con-
ditions of rotation we have supposed.

In the four- course manured rotation upon the heavy
land at Rothamsted, the nitrogen annually removed in the
crops, on an average of forty years, -has exceeded by
about 32 Ibs. the quantity supplied in the manure. If
the crops on this experimental rotation should be perma-
nently maintained in quantity, of which at present we
cannot be certain, we must conclude that these 32 Ibs. of
nitrogen, together with the unknown additional quantity
lost as nitrate by drainage, have been annually derived
from the atmosphere — partly as rain, but mostly by direct
absorption by the crops or soil.

When it is desired to make the utmost use of the
natural sources of fertility, the land is allowed to remain
more than one year in grass seeds ; or one green crop is
followed by another, as trifolium incarnatum by turnips ;
or a perennial leguminous crop is grown for several
years. The losses by sale of corn are thus diminished,
and the land is kept for some time under conditions
favourable to an accumulation of nitrogen in the surface
soil.

We have supposed that only corn and meat are sold
off the land during the rotation ; it will often be economi-
cal to sell a larger part of the produce and to purchase
manure in its place. The sale of straw will be attended
with little practical loss on heavy land ; but on light land
both the loss of potash, and the diminution in the bulk of

74 THE CHEMISTRY OF THE FAEM.

the manure will be more or less felt. The sale of hay or
roots is far more exhaustive, and, except on the most fer-
tile soils, must demand a considerable purchase of
manure or cattle food to replenish the soil with plant
nourishment.

CHAPTER VI.

ANIMAL NUTRITION.

The Constituents of tlie Animal Body. — Water, albuminoids, gelatinoids.
horny matter, fat, and ash constituents — Composition of animals in
various stages of growth and fattening — Composition of wool and
milk — Loss to a farm by sale of milk, cheese, and butter — Proportion
of carcase in different animals — Composition of increase whilst fat-
tening. The Processes of Nutrition. — The constituents of food,
their particular functions in the body and relative values — Diges-
tion— Respiration — Excretion.

IN order to understand the mode in which animals are
nourished we must first obtain some acquaintance with
the nature of the animal body, and understand the compo-
sition of the increase which takes place during growth
and fattening.

The Constituents of Animals.— The elements com-
posing the animal frame are the ten already named as
forming the essential constituents of plants (pp. 2 — 3),
with sodium and chlorine in addition. The two last-
named elements are commonly present in the succulent
parts of plants, but are apparently not essential to plant
life ; in the animal frame they are, however, indispens-
able. Fluorine and silicon are also always found in the
animal body, but are not known to be essential for life or
growth ; fluorine occurs in small quantities in the teeth
and bones, and silicon in hair, wool, and feathers.

76 THE CHEMISTEY OF THE FARM.

The combustible matter of the animal body is mainly
composed of nitrogenous substances, and of fat.

The nitrogenous substances constituting the animal
frame may be generally classed as — (1) albuminoids
(proteids) ; (2) gelatinoids ; and (3) horny matter. These
three groups are related in composition, though differing
a good deal in their properties. The albuminoids form
the substance of animal muscle and nerve, and the greater
part of the solid matter of blood ; they are, undoubtedly,
of the first importance in the animal economy. The
gelatinoids form the substance of skin and sinew, of
all connective tissue, and also the combustible matter
of cartilage and bone. Horny matter, named by
chemists keratin, is the material of which horn, hair,
wool, and feathers are constituted. Besides the nitro-
genous matters constituting tissue, the animal juices
contain a variety of nitrogenous substances, as sarcine,
creatine, etc., with which we are not immediately con-
cerned.

The fats occurring in the animal body are principally
stearin, palmitin, and olein. Stearin preponderates in
hard fats, and olein in fluid fats.

Of the incombustible constituents by far the largest
part is contained in the bones. In fat animals 75 to 85
per cent, of the total ash constituents are found in the
bones. Bone ash chiefly consists of phosphate of calcium,
with a small quantity of carbonate of calcium and phos-
phate of magnesium. In muscle by far the most abundant
ash constituent is phosphate of potassium. Potassium
salts are also abundant in the " yolk " of unwashed wool.
Blood, on the other hand, always contains a considerable
quantity of sodium salts.

ANIMAL CONSTITUENTS.

77

The amounts of water, nitrogenous matter, fat, and
ash constituents present in a large number of animals
have been determined at Kothamsted. The following
table shows the percentage composition of eight animals,
after deducting the contents of the stomachs and in-
testines. The fat pig was one grown for fresh pork, not
for bacon.

PERCENTAGE COMPOSITION OF WHOLE BODIES OF ANIMALS.

Fat

Half

Fat

Fat

Store

Fat

Extra

Store

Fat

calf.

fat ox.

ox.

lamb.

sheep.

sheep.

sheep.

pig.

Pig.

Water.

65'1

56-0

48-4

52-2

61-0

46-1

37-1

58-1

43-0

Nitrogenous

matter

15-7

181

15-4

13-5

15-8

13-0

11-5

14-5

11-4

Fat .

15-3

20-8

32-0

31-1

19-9

37-9

48-3

24-6

43-9

Ash .

3-9

5-1

4-2

3-2

3-3

3-0

3-1

2-8

1-7

Water is in nearly every case the largest ingredient of
the animal body ; the proportion of water diminishes with
the growth of the animal, and especially during fattening.
Fat forms in most cases the principal solid ingredient of
well-fed animals, its proportion increases very largely
during fattening. The proportion of nitrogenous matter
and ash tends to increase from youth to maturity, but
diminishes during fattening.

The largest proportion of nitrogenous matter and of
ash are found in the ox, the smallest in the pig. The
difference in the proportion of ash is chiefly due to the
wide difference in the proportion of bone in these two
animals. Fat is found in greatest quantity in the pig,
and is least in the ox.

The following table shows the quantity of nitrogen, and
of the principal ash constituents, in the fasted live weight
of the animals analysed at Rothamsted. For convenience

73

THE CHEMISTRY OF THE FARM.

of comparison each animal is assumed to weigh 1000 Ibs.
The table also gives the nitrogen and ash constituents in
wool and milk ; it thus supplies full information as to the
loss which a farm will sustain by the sale of animal pro-
duce. The composition of wool is deduced from foreign
analyses.

ASH CONSTITUENTS AND NITROGEN IN 1000 POUNDS OF
VARIOUS ANIMALS AND THEIR PRODUCTS.*

Nitrogen.

Phospho-
ric Acid.

Potash.

Lime.

Magnesia.

Ibs.

Ibs.

Ibs.

Ibs.

Ibs.

Fat calf .

24-64

15.35

2-06

16-46

0-79

Half-fat ox

27-45

18.39

2-05

21-11

0-85

Fat ox .

23-26

15-51

•76

17-92

0-61

Fat lamb

19-71

11-26

•66

12-81

0-52

Store sheep

23'77

11-88

•74

13-21

0-56

Fat sheep

19-76

10-40

•48

11-84

0-48

Store pig

22-08

10-66

•96

10-79

0-53

Fat pig .

17-65

654

•38

6-36

0-32

Wool, unwashed

54'GO

0-70

56-20

1-80

0-40

,, washed

94-40

1-80

1-90

2-40

0-60

Milk

5-92

2-00

1-70

1-70

0.20

* The constituents of animals are reckoned in this table on a fasted
live weight including contents of stomachs and intestines.

These figures show that the ox contains in proportion
to its weight a larger amount of nitrogen, and a much
larger amount of phosphoric acid and lime, than either the
sheep or pig. Of all the animals raised on a farm the
pig contains least of all the important ash constituents.

The large amount of potash in unwashed wool is very
remarkable ; a fleece must sometimes contain more potash
than the whole body of the shorn sheep.

If we assume a cow to yield 600 gallons of milk in the
year, and the milk to be sold, the loss to the farm will be
about 3(5 Ibs. of nitrogen, 12 Ibs. of phosphoric acid, and
10 Ibs. of potash. If the milk is made into cheese the

ANIMAL CONSTITUENTS.

79

annual loss will be about 28 Ibs of nitrogen, 7 Ibs. of
phosphoric acid, and 1 Ib. of potash. If only butter is
sold the loss of nitrogen and ash constituents will be
quite insignificant.

In a fat ox about 60 per cent, of the fasted live weight
will be butchers' carcase ; in a fat sheep about 58 per cent.;
in a fat pig (fatted for pork) 83 per cent. The proportion
of carcase increases considerably during fattening. Thus
the carcase in the store sheep killed at Rothamsted
averaged 53'4, in the fat sheep 58*6, and in the very fat
sheep 64*1 per cent, of the fasted live weight.

When a lean animal is fattened the larger part of
the increase in live weight is carcase. It was found at
Eothamsted that in the case of sheep passing from the
tf store " to the " fat " condition, increasing in weight from
102 Ibs. to 155 Ibs., about 68 per cent, of the increase was
carcase. With " fat " sheep passing into the " very fat "
state, increasing from 144 Ibs. to 202 ibs. live weight, the
proportion of carcase in the increase was about 77 per cent.
With a fattening pig, increasing from 103 Ibs. to 191 Ibs.
live weight, the proportion of carcase in the increase was
found to be 91 per cent.

The percentage composition of the increase of sheep
and pigs when passing from the "store " to the " fat"
condition is about as follows. The increase of fattening
oxen will have a similar composition.

PERCENTAGE COMPOSITION OF THE INCREASE WHILST
FATTENING.

Sheep .
Pigs

Water.

Nitrogenous
matter.

Fat.

Ash.

22'0

28-6

7-2

7-8

68-8
631

2-0
0-5

80 THE CHEMISTRY OF THE FAEM.

The increase during the fattening stage of growth is
seen to be chiefly an increase in fat, eight to nine parts of
fat being laid on for one of nitrogenous matter. The
proportion of fat would be somewhat greater still in the
increase of highly fattened animals, as, for instance, of
pigs fed for bacon.

The Processes of Nutrition.— We have already seen
that the food of plants is of the simplest character. From
such simple substances as carbonic acid, nitric acid, water,
and a few salts, a plant is able to construct a great variety
of elaborate compounds. It accomplishes these surprising
transformations by a consumption of force (sunlight)
external to itself. An animal has no such constructive
power. The animal frame is built up of substances ex-
isting ready formed in the food, or produced by the
splitting up or partial combustion of some of the
food constituents in the body. The animal derives
no aid from external force. The temperature of the
animal (about 100° Fahr.) is maintained by heat gene-
rated within the body by the combustion of the materials
consumed as food. The force by which all the mechanical
work of the animal is performed is also derived from the
same source. The source of heat and force in the animal
is thus purely internal.

It is evident from what has just been said that the
food of animals has duties to perform which are not de-
manded of the food of plants. In plants the food merely
provides the matter for building up the vegetable tissues.
In the animal, besides constructing tissue, the food has to
furnish the means of producing heat, and executing
mechanical work.

K)OD CONSTITUENTS. SI

1. Food Constituents and their Functions. — The solid
ingredients of vegetable food may be classed generally
as — (1) albuminoids (proteids); (2) fat; (3) carbo-
hydrates; (4) salts. Besides these general ingredients of
food we have in immature vegetable products a fifth
class — the amides, which also takes part in animal
nutrition. The albuminoids and amides are nitrogenous
substances, the other ingredients of food are non-
nitrogenous.

The albuminoids occurring in corn, roots, and other
forms of vegetable food, are quite similar in composition
to those found in milk, blood, and flesh. From the
albuminoids of the food are formed not only the albumin-
oids of the animal frame, but also the gelatinoids, the
hair, wool, horn, &c., and to some extent the fat. By
the combustion of albuminoids in the body heat and
mechanical force will also be developed. Albuminoids
thus supply in themselves most of the requirements of
the animal — a statement which can be made of no other
food constituent. The albuminoids of food are frequently
described as " flesh -formers."

An animal, even when not increasing in weight, will
always require a certain constant supply of albuminoid in
its food to replace the waste of nitrogenous tissue which
is always going on. The amount of digestible albuminoid
required for this purpose is but small ; in the case of an
adult man it is not more than forty grams (I '4 oz.) per
day. For the requirements of animals see p. 120.

When the nitrogenous tissues, or the albuminoids con-
sumed as food, are oxidised in the body, the nitrogen
they contain is not burnt, but excreted in the form of
urea. The urea produced is one-third the weight of

82 THE CHEMISTRY OF THE FARM.

the albumin oxidised.* When the albuminoids, either of
the food or of the wasting tissues, are only partially
oxidised, fat as well as urea may be produced. According
to the new determinations of the heat evolved on combus-
tion, 100 parts of albumin must yield less than 47 parts
of fat.

The amides consumed as food are burnt in the system,
and their nitrogen excreted as urea. Amide? cannot
supply the place of albuminoids as muscle-formers, but by
combustion they serve for the production of heat and force.

The fats contained in food are similar to those found
in the animal body, but an animal is apparently capable
of transforming one kind of fat into another. The fat
of the food is either burnt in the animal system to furnish
heat and mechanical energy, or it is stored up as reserve
matter. Fat has a greater value as a heat and force
producer than any other ingredient of food.

The carbo-hydrates of the food are chiefly starch,
sugar, and cellulose ; these substances consist of carbon,
hydrogen, and oxygen, the last two elements being in
the proportion to form water — hence the name. Various
other non-nitrogenous constituents of food, as pectin,
lignin, and vegetable acids, are also generally included
under this title, though not, strictly speaking, carbo-
hydrates. Carbo-hydrates form the largest part of all
vegetable foods. They are not permanently stored up in
the animal body, but serve, when burnt in the system,
for the production cf heat and mechanical work. They
are also capable, when consumed in excess of immediate
requirements, of conversion into fat.

* There are small quantities of other nitrogenous products, as uric
and (in the case of herbivorous animals) hippuric acid, voided in the
urine, but they do not in this place require our attention.

FOOD CONSTITUENTS. 83

The carbo-hydrates and fat are quite incapable of
adding to the nitrogenous tissues of the body. They may,
however, have this effect indirectly by protecting the
albuminoids of the food from oxidation. A moderate
quantity of albuminoids supplied to a growing animal
will thus produce a larger increase of muscle when ac-
companied by a supply of carbo-hydrates or fat than if
consumed alone. In the former case the non-nitroge-
nous ingredients of the food supply the heat and force
demanded by the animal body, in the latter case the
albuminoids have to meet every requirement.

If an adult animal receives the small quantity of
albuminoids and salts necessary to supply the waste of
tissue, the whole of its remaining wants may be met by
supplies of carbo-hydrates and of fat.

The relative value of food constituents for the produc-
tion of heat and force depends on the amount of heat
evolved during their oxidation. It has been found that
100 parts of fat when burnt give the same amount of
heat as 213 parts of the albuminoids of muscle, 469 parts
of asparagine (the heat yielded by the matter excreted as
urine when these substances are consumed in the body
is in both cases deducted), 229 parts of starch, 235 parts
of cane sugar, or arabic acid (gum), and 255 parts of
glucose, or crystallised milk sugar. Digested cellulose
has a smaller value than the carbo-hydrates just named,
267 parts are probably equivalent to 100 of fat.

The ash constituents present in the food are the same
as those found in the animal body; all that is accom-
plished by the animal is to select from the supply those
of which it is in want.

2. Digestion. — The object of digestion is to bring

84 THE CHEMISTEY OF THE FARM.

the solid constituents of the food into a form suitable for
absorption into the blood. Of the carlo -hydrates of the
food some, as sugar, are already soluble and diffusible,
and need no digestion; others, as starch and cellulose,
are naturally insoluble. The digestion of carbo-hydrates
commences with the action of the saliva, which has the
property of converting starch into sugar (maltose).
Phis action, in the case of ruminants, is prolonged by the
temporary sojourn of the food in the first two stomachs,
and its return to the mouth in chewing the cud. The
digestion of the cellulose by a fermentive process com-
mences in the paunch. The further solution of starch
and cellulose is effected in the intestines. The pancre-
atic juice has a powerful action on starch. In the intes-
tines maltose is converted into dextrose. The cellulose is
dissolved in the colon by a fermentive process, due
apparently to bacteria, in which acetic and butyric acids,
carbonic acid, and a little marsh gas are the products.

The albuminoids of the food are attacked by the
gastric juice of the stomach (the fourth stomach of rumi-
nants), and converted into peptones, bodies similar to
albuminoids in composition, but which, unlike them, are
diffusible through a membrane. The pancreatic juice of
the small intestines also converts albuminoids into pep-
tones, and partly into amides, leucine and tyrosine.

The digestive agents in saliva, gastric juice, and pan-
creatic juice, are unorganised ferments (enzymes), known
respectively as ptyalin, pepsin, and trypsin.

Fat, liquefied by the heat of the body, is probably
capable of absorption without change. The digestion of
fat in large quantities is greatly assisted by the bile and
pancreatic juice.

RESPIRATION. 85

The absorption of the dissolved constituents of the
food takes place more or less in all parts of the alimentary
canal, but chiefly in the small intestines. The absorbed
matters pass into the blood.

The blood of an animal is the source of nourish-
ment to the whole body ; out of its ingredients all
the tissues are formed. The blood is also the means
of conveying to the tissues the oxygen which is
essential to their vitality, and of removing from them
carbonic acid, and the other products of their meta-
morphosis.

3. Respiration. — The blood is supplied with oxygen
during its passage through the lungs, where it is brought
into contact with air. The oxygen is absorbed by the
haemoglobin, which forms the chief constituent of the red
blood corpuscles. The scarlet blood thus produced is
circulated through the whole body by the arteries ; the
oxygen it supplies is consumed in the tissues, producing,
among other results, heat and mechanical work. The
blood finally returns from the tissues by the veins. The
haemoglobin has then lost its oxygen, and has assumed a
purple colour ; the blood serum also contains carbonic
acid gas in solution, and many other products of decom-
position. By passing again through the lungs the car-
bonic acid is more or less completely discharged, and a
fresh supply of oxygen obtained.

4. Excretion. — The products which result from the
oxidation of tissue, or of the food consumed, are removed
from the body by the lungs, the kidneys, or the skin.
The chief products of oxidation in the body are carbonic
acid, water, urea, and salts. Carbonic acid is removed
through the lungs, and to a smaller extent by the skin ;

86 THE CHEMISTRY OF THE FARM.

ui-ea and salts by the kidneys ; water by all the organs
of excretion.

Non-nitrogenous substances, as fat and sugar, when
oxidised in the body, yield simply water and carbonic
acid. The nitrogen of the albuminoids, gelatinoids, and
amides, is not oxidised, but is excreted in the form of
urea. The sulphur of the albuminoids is in part
oxidised to sulphuric acid.

The quantity of nitrogen in the urine is a measure of
the albuminoids, gelatinoids, and amides oxidised in the
body. In the urine, and in the perspiration of the skin,
are also removed all the salts not required for the animal
economy. Sodium and potassium salts are generally
abundant in the urine.

The solid excrement contains the undigested part of
the food, with the residues of the bile and other secre-
tions of the alimentary canal.

CHAPTER VII.

FOODS.

The Composition of foods. — Detailed composition — Proportion of nitre-
gen existing as true albuminoids — Comparison of foods. Circum-
stances producing Variation. — Influence of age and manuring —
Changes during haymaking and ensilage. Digestibility of Foods. —
Method of determination — Experiments with ruminants — Experi-
ments with horses — Experiments with pigs — Experiments with
geese and fowls. Circumstances affecting Digestibility. — Influ-
ence of age of animal, daily ration, and labour — Influence of
cooking on digestibility — Influence of the maturity of fodder
crops on their digestibility — Influence of one food on the diges-
tibility of another — Common salt. Comparative Nutritive Value
of Foods. — Comparative power of producing heat and work —
Proportion of albuminoids to non-albuminoids — Influence of pro-
portion of water — General conclusions.

IN the preceding chapter we have enumerated the
chief constituents of food, and described their functions
in the animal body; we may now proceed a step further,
and consider the detailed composition and feeding value
of the foods actually employed on the farm.

The nourishing value of a food is plainly fixed by two
factors : — 1. Its composition. 2, Its digestibility. The
first of these determines the richness of the food in albu-
minoids, fat, carbo-hydrates, and ash constituents. The
second determines the extent to which these various con-
stituents are made use of in the animal body.

Composition of Poods.— The average percentage com-
position of the foods commonly given to farm animals is

THE CHEMISTRY OF THE FARM.

shown in the following table. The figures given are in
every case the mean of a large number of analyses.

PERCENTAGE COMPOSITION OF ORDINARY FOODS.

Food.

Water.

Kitrogenous
substance.

1

Soluble
carbo-
hydrates.

8

e

4

-<

, »

11

1

Cotton cake (decorticated)

8-2

44-0

13-5*

21-5

6-0

6-8

40-9

Cotton cake (undecorti-

cated)

12-2

20-8

5-4

35-6

20-8

5-2

19-3

Linseed cake

11-7

27-0

11-4 1

84-2

9-0

6-7

25-4

Beans

14-5

25-5

1-6

45-9

9-4

3-1

22-4

Peas

14-3

22-4

2-0

52-5

6-4

2-4

19-7

Oats

]3-0

12-9

6-0

55-4

10-0

2-7

11-9

Wheat

12-3

11-7

1-8

70-0

2-4

1-7

10-2

Rye

14-0

11-0

2-0

67-4

3-5

1-8

?

Barley

14-0

10-6

2-0

64-1

71

2-2

10-0

Maize

iro

10-4

5-1

70-0

2-0

1-5

9-7

Malt dust

10-0

23-7

2-2

43-8

13-5

6-8

17-3

Wheat bran .

14-0

14-5

4-0

51-3

10-1

61

12-3

Brewers' grains

76-6

4-9

1-1

11-0

5-2

1-2

4-8

Brewers' grains (dried)

9-3

20-2

7-7

43-6

15-0

4-2

19-8

Rice meal

10-0

11-9

121

47-0

9-0

10-0

111

Clover hay (medium) .
Meadow hay (medium)

16-0
14-3

12-3

9-7

2-2
2-5

38-2
41-0

26-0
26-3

5-3

6-2

10-2
8-3

Bean straw

16-0

8-1

1-0

35-3

35-0

4-6

?

Oat straw

14-3

4-0

2-0

36-2

39-5

4-0

3-8

Barley straw . .

14-3

3-5

1-4

36-7

40-0

4-1

3-2

Wheat straw

14-3

3-0

1-2

36-9

40-0

4-6

2-9?

Pasture grass

80-0

3-5

0-8

9-7

4-0

2-0

2-6

Red clover (before bloom)

83-0

3-3

0-7

7-0

4-5

1-5

2-5?

Potatos

75-0

21

0-2

20-7

1-1

0-9

1-3

Carrots

86-0

1-3

0-2

10-0

1-6

0-9

0-7

Mangels .

88-0

1-1

o-i

8-9

1-0

0-9

0-4

Swedes

89-3

1-4

0-2

7-4

1-1

0-6

0-7

Turnips

92-0

1-0

0-2

5-2

0-9

0-7

0-5

* The cake lately imported contains often only 8—10 per cent, of oil.
t Hard-pressed linseed cakes contain 7 — 10 per cent, of oil ; lightly-pressed cakes.
11—13 per cent. Some Russian cakes contain 14—20 per cent.

ALBUMINOIDS IN FOODS.

89

The " soluble carbo-hydrates " in the above table
include starch, pectin, and the finer parts of the fibre ;
these are not soluble in water, but are dissolved by the
weak acid and alkali employed by the analyst to separate
the coarse fibre. In the straw of cereals nearly the whole
of the " soluble carbo-hydrate " is cellulose.

The " nitrogenous substance " in the table is obtained
by multiplying the percentage of nitrogen by 6'25, it
thus represents the amount of albuminoids present, if we
assume that the whole of the nitrogen exists in this form.
It has however been shown during the last few years
that a part of the nitrogen of vegetable foods exists, not
as albuminoids, but as amides (asparagine, glutamine,
leucine, tyro-sine, &c.), and in some cases as nitrates.
The following table shows the average proportion of the
nitrogen which exists in the form of albuminoids in
various foods, according to the analyses at present pub-
lished ; numbers marked with an asterisk are the mean
of few analyses.

PROPORTION OF ALBUMINOID NITROGEN IN VARIOUS
FOODS PER 100 OF TOTAL NITROGEN.

Cotton cal

ce

93

Malt dust

72

Linseed ca

ke

94

Brewers* grains

i

98*

Beans

t

88

Oat straw

80*

Peas

t

88

Barley straw

90*

Oats

94

Meadow hay

85

Wheat

,

90*

Clover hay

83

Barley

94

Grass (young)

75

Maize

93

Potatos

60

Rice meal

94*

Carrots

52

Wheat bra

n

|

85

Turnips .

49

Malt

79

Mangels .

37

90 THE CHEMISTRY OF THE FARM.

It appears from these numbers that the greater part
of the nitrogen in ripe seeds exists as albuminoids. In
wheat grain the proportion of albuminoid nitrogen is
rather low, owing to the considerable proportion of non-
albuminoid nitrogen contained in the bran ; on this point,
however, further analyses are needed. In germinated
grain, as malt, a considerable part of the albuminoids is
replaced by amides. The few analyses of ripe straw show
that the nitrogen present is chiefly albuminoid. In im-
mature produce the proportion of non -albuminoid nitrogen
is much more considerable. The albuminoids are in
largest proportion in hay, in smaller proportion in green
fodder, and in still smaller proportion in roots and tubers.
In mangels a considerable part of the non-albuminoid
nitrogen exists as nitrates. The circumstances producing
variation in the proportion of albuminoids will be con-
sidered presently.

"We may now consider the average composition of the
various foods mentioned in the table.

The amount of total dry matter is seen to be tolerably
uniform throughout the various classes of dry foods, the
foods richest in fat being generally the driest. Corn and
straw in bulk will frequently contain a somewhat larger
amount of water than that mentioned in the table. In
green fodder and roots the proportion of water reaches
its maximum. Of the roots and tubers, potatos contain
the largest, and white turnips the least proportion of dry
matter.

We have already seen that albuminoids and fat are
the most concentrated forms of food which an animal can
consume ; those foods which are rich in albuminoids and
fat have therefore, if digestible, the highest nourishing

COMPAEISON OF FOODS. 91

value. At the head of all foods in this inspect stand tho
various descriptions of oilcake ; they are, without doubt,
among the most concentrated foods at the farmer's dis-
posal. The leguminous seeds, as beans, peas, and lentils,
are rich in albuminoids, but not in fat. The cereal grains
are much poorer in albuminoids, containing only about
one half the proportion found in leguminous seeds. Of
the common cereals, oats are generally the most nitro-
genous, and maize the least. Oats and rnaiza are char-
acterised by containing more fat than the other cereal
grains. The special characteristic of all the cereal grains
is their richness in an easily-digested carbo-hydrate,
starch.

Of the cereal products mentioned in the table,
the bran, brewers' grains, and rice meal, represent
respectively the external covering of wheat, barley,
and rice. These foods are richer both in nitro-
genous matter and fat, but contain a much moro
considerable proportion of fibre than the whole grain.
Malt-dust (known also as malt combs) consists of the
radicles of the germinated barley, which are removed
after the malt has been dried. This material is very rich
in nitrogenous matter, a considerable proportion of which,
however, is in the form of amides.

In the case of hay, straw, green fodder, silage, and
roots, the general composition is a less safe guide to the
nourishing value. The nitrogen is here no certain measure
of the proportion of albuminoids present. The fat credited
to these foods includes indigestible waxy matter ; in the
case of green fodders, chlorophyll ; and in the case of
silage, lactic acid; these substances being all equally-
dissolved by the ether used to separate the fat. The

92 THE CHEMISTRY OF THE FAR1T.

carbo-hydrates also include various substances of little
feeding value. The same weight of dry matter in crude
foods of this class has thus a decidedly less nourishing
value than in foods consisting entirely of matured grain.
Foods belonging to different classes cannot safely be
compared on the basis of their composition.

Most foods supply a sufficient quantity of: the ash
constituents which are required for the formation of bone
and muscle ; the chief of these are phosphoric acid, lime,
and potash. The oilcakes and bran are the foods richest
in phosphoric acid ; straw and meadow hay are the foods
poorest in this constituent. Lime is most abundant in
clover hay, bean straw, and turnips, and occurs in least
quantity in the cereal grains and in potatos. Potash is
abundant in roots, hay, bean straw, bran, and oilcake,
and is found in smallest quantity in the cereal grains.
The proportion of phosphoric acid and potash in various
foods is shown in the table on page 139.

Of all the ash constituents lime and soda are pro-
bably the most generally deficient. Maize is of all
ordinary foods (rice excepted) the poorest in lime ; it
certainly contains too small an amount for a rapidly
growing animal. At Eothamsted a mixture of coal
ashes, common salt, and superphosphate was used with
advantage in the case of young pigs fed solely on maize.
It must be recollected, however, that animals will gener-
ally receive no inconsiderable amounts of lime in their
drinkirg water,

Circumstances producing Variatiou'in Composition.—
The composition of all vegetable foods is liable to varia-
tion, depending on the state of maturity of the plant, and

VARIATIONS IN POODS.

93

the character of the soil and season. In the case of per-
fectly matured produce, as, for instance, ripe seed, the
variations in composition are not generally considerable,
and an average composition, such as is given in the table,
will be found in most cases pretty correct. But in the
case of immature produce, such as meadow grass, tur-
nips, or maugels, the composition largely depends on the
stage of growth in which the plant is taken, and is also
greatly affected by the character of the manuring. It
may be generally stated that as a plant matures the pro-
portion of water, nitrogenous matter, and ash constitu-
ents diminishes, while the proportion of carbo-hydrates
largely increases, At the same time the amides become
more or less converted into albuminoids.

The following table shows the percentage composition
of meadow grass cut at three different dates in the same
field. The first cutting will represent pasture grass fed
off in the green state by stock ; the second cutting is
good ordinary hay; the third cutting is an over- ripe hay,
somewhat coarse and stemmy, but well harvested. The
composition given in every case is that of the dry sub-
stance : —

COMPOSITION OF HAY HAEVESTED AT DIFFERENT DATES.

Date of Cutting.

Nitrogenous
substance.

Fat.

Soluble
carbo-hydrates.

Fibre.

Ash.

May 14 .
June 9 .
June 26 .

17-65
11-16
8-46

3-19
2-74
2-71

40-86
43-27
43-34

22-97

34-88
38-15

15-33
7-95
7-34

Young grass is thus much richer in nitrogenous sub-
stance, and contains a smaller proportion of indigestible

94 THE CHEMISTKY OF THE FARM.

fibre than older grass, and is consequently more nourish-
ing. The same comparison may be made between young
clover and that which is allowed to mature for hay.
Fodder crops should be cut for hay immediately full
bloom is reached; after this point the quality of the hay
will considerably deteriorate.

While fodder crops deteriorate towards maturity,
from the conversion of soluble carbo-hydrates into fibre,
crops such as potatos and mangel improve, the carbo-
hydrates produced in their case being respectively starch
and sugar, both of them substances of great feeding
value.

The influence of high manuring on the composition
of a crop is generally considerable. A luxuriant crop
will always contain more water than one in less active
growth. Very large mangels often contain only 6 per
cent, of dry matter, while in quite small roots the pro-
portion may be as high as 15 per cent. Luxuriance also
retards maturity. A heavily manured mangel will con-
tain, at the same date, a much smaller proportion of
sugar than a similar mangel grown on poorer soil. The
result of liberal nitrogenous manuring is thus not only to
increase the bulk of the crop, but also generally to
diminish the proportion of carbo-hydrates, and increase
the nitrogen, ash constituents, and water. In highly
manured crops a smaller proportion of the nitrogen will
exist as albuminoids than in crops less heavily manured
and more mature. Thus, in a crop of mangels of 18 tons
per acre, manured with farmyard manure, the albuminoid
nitrogen amounted to 38 per cent, of the total nitrogen ;
while in a crop of 28 tons, receiving nitrate of soda and
superphosphate in addition to the dung, the albuminoid

ENSILAGE. 95

nitrogen was only 29 per cent, of the total. It is evident
that large mangels or turnips, produced by liberal
manuring, are less nutritious than smaller roots. Potatos
do not deteriorate in quality as they increase in size.

In the case of hay the composition is further affected
by the conditions of haymaking, and by the subsequent
changes in the rick. Grass that has suffered from rain
during haymaking will contain less soluble matter (carbo-
hydrates and albuminoids) than well-made hay ; this loss
will be greatly increased if the hay has been long in the
field, and undergone fermentation as well as washing.
The changes which take place in the rick are seen on a
larger scale in the process of ensilage.

When green fodder is stored in a silo the mass be-
comes hot from oxidation, a loss both of water and solid
matter takes place, carbonic acid and other gases being
evolved. If the green fodder has been cut small, and
compressed by weights as soon as it was placed in the
silo, oxidation is at a minimum ; under these circum-
stances alcoholic, lactic, and butyric fermentation sets in
more or less strongly, and " sour silage " is produced.
If, on the other hand, the silo is filled gradually, and a
few days elapse before the weights are applied, the tem-
perature rises much higher, owing to the greater bulk of
air enclosed. If the mass is weighted as soon as 140° —
160° Fahr. is reached, " sweet silage " will result, the
high temperature having been fatal to the living organ-
isms which produce an acid fermentation. In making
silage the loss of solid matter falls chiefly on the carbo-
hydrates. The total nitrogen is scarcely altered in quan-
tity, but a considerable part of the albuminoids is de-
stroyed, the nitrogen being found in the silage as amides,

THE CHEMISTRY OP THE FAEM.

or as ammonium salts. In the case of " sour silage "
one-third of the albuminoids is not unfrequently de-
stroyed. In making sweefc silage there is, apparently, a
smaller destruction of albuminoids. The final product,
in this case, contains a larger proportion of soluble carbo-
hydrates, and little or no acid. The total loss of solid
matter is probably greater in making sweet, than in
making sour silage.

Digestibility of Poods.— Our knowledge concerning
the digestion of food by farm animals is almost entirely
derived from German investigations ;* much information
has already been obtained upon this subject, though a
great deal yet remains to be accomplished. The general
method of investigation has been to supply an animal with
weighed quantities of food, the composition of which
has been ascertained by chemical analysis. During this
experimental diet the solid excrements are collected and
weighed, and are finally analysed by the same chemical
methods previously applied to the food. Subject, there-
fore, to certain small corrections for intestinal secretions,
we obtain by this plan the amount of each constituent of
the food which has passed through the animal unabsorbed,
and by difference the amount digested. The proportion
of each constituent digested for 100 supplied in the food
is known as its " digestion coefficient."

1. Experiments with Ruminants. — Ruminating animals
possess an extensive digesting apparatus, consisting of
the well-known four stomachs, in addition to the intesti-
nal organs. Food takes a considerable time in passing

* The information given in this section is taken to a great extent from
the admirable work of Dr. E. Wolff, " Die Ernahrung der Landwirth-
schaftlichen Nutzthiere,'' and its valuable Supplement.

DIGESTIBILITY OF FOODS.

97

through this system. In changing the diet of an ox, five
days will generally elapse before the remains of the pre-
ceding diet are entirely expelled by the animal. Animals
of this class are specially adapted for the digestion of
bulky foods containing much fibre.

Experiments have been made with oxen, cows, sheep,
and goats. The power of these different animals for di-
gesting food is apparently very similar, but no accurate
comparisons have as yet been made. The following table
shows the average results obtained with ruminating
animals fed on the foods respectively mentioned. The
figures given represent the " digestion coefficients " found
for each constituent of the food consumed.

EXPERIMENTS WITH CATTLE, SHEEP, AND GOATS.

Digested for 100 of each constituent

supplied.

Food.

o .

P

o ,g

"S-'S &

W H

•

c?

m

f+i
C/3
£

2

III

1

gjS

*

Meadow hay (medium) .

60

57

48

62

58

Clover hay (medium) . ,

57

55

51

65

45

Lucerne hay (very good)

60

74

39

66

43

Oat straw ....

50

35

35

45

57

*Barley straw

53

20

42

54

56

*Wheat straw

46

17

36

39

56

*Bean straw ....

51

49

56

64

39

* Cotton cake (decorticated) .

80

85

88

84

?

* Cotton cake (undecorticated)

52

74

91

50

16

* Linseed cake

81

86

90

80

44

*Peas

90

89

75

93

66?

Beans

89

88

87

92

72?

Oats

71

79

84

76

24

* Barley .

81

77

100

87

* Maize

89

79

85

91

^

*Rice meal

89

77

88

100

67

Wheat bran

72

78

69

77

33

*Malt dust

84

82

49

88

95

*Brewers' grains

63

73

84

64

39

These results are derived from a few experiments.

9$ THE OHEMISTR? OF THE

The digestibility of the foods in the upper division
of the table has been for the most part determined by
feeding the animals on these foods alone; the digesti-
bility of the foods in 'the lower division of the table,
and also of roots, has been found by supplying these
foods in various proportions along with hay, the digesti-
bility of which had been already ascertained with the
same animal.

In the case of ordinary meadow and clover hay
the total organic matter digested is but 55 to 60 per
cent, of that supplied ; with hay of exceptional quality
the proportion digested may rise to 70 per cent. With
straw only 45 to 50 per cent, of the organic matter is
generally digested, the minimum occurring with wheat
straw.

The digestibility of the nitrogenous matter in hay and
straw appears to increase as its proportion rises. A
sample of wheat straw experimented with contained
4*8 per cent, of nitrogenous matter in its dry substance,
of which only one-fifth, or 20 per cent., was digested ;
while good lucerne hay with 19*3 per cent, of nitrogenous
matter had 76 per cent, of this in a digestible form.
The precise nature of the digested and undigested nitro-
genous matter has not yet been ascertained ; amides being
soluble bodies have undoubtedly been usually reckoned as
digestible albumin.

Of the fibre in hay and straw about 40 to 60 per cent.
is generally digested by ruminant animals. The fibre of
leguminous hay and straw (clover and lucerne hay, and
bean straw) is less digestible than the fibre of similar
graminaceous foods (grass hay, oat and wheat straw). It

DIGESTIBILITY OF FOODS. 99

has been shown that both in the case of the soluble carbo-
hydrates, and of the fibre, the portion digested has always
the general formula of starch or cellulose, C6H1005, while
the portion left undigested is much richer in carbon.
It appears, therefore, that while cellulose is digested
to a considerable extent, the lignin which is deposited
on the tissues as the plant increases in age, and which
contains a larger proportion of carbon, is much less
digestible. Chemical analysis shows that the fibre of
leguminous hay and straw is richer in carbon, and conse-
quently in lignin, than the fibre of grass hay or cereal
straw.

The concentrated foods placed in the lower section of
the table are seen to be far more thoroughly digested than
is the case with hay or straw. When of good quality, 80
to 90 per cent, of the organic matter of these foods will
be assimilated by the animal, except in those cases where
much fibre is present. The albuminoids and fat in these
foods have especially a greater digestibility than the same
ingredients in hay and straw. The amount of fibre is
usually too small for its digestibility to be determined
with certainty. The hard fibre forming the husk of seeds
is apparently but little digested. The oats employed were
of somewhat inferior quality.

Eoots and potatos are not mentioned in the table;
they are apparently very thoroughly digested.

2. Experiments with Horses. — In experiments con-
ducted by Wolff the digestive powers of the horse and
sheep have been accurately compared, the same food
having been supplied to each animal.

100 THE CHEMISTRY OP THE FARM.

The principal results were as follows : — •
EXPEKIMENTS WITH HOUSES.

Food.

Proportion of each constituent digested
for 100 supplied.

o .

111

1

Hi

I

* Pasture grass
Meadow hay (very good)
Meadow hay (ordinary)
Red clover hay
Lucerne hay (very good)
*0ats
* Beans
* Maize

62
51

48
51
58
68
87
91

69
62
57
56
73
86
86
78

13

20
24
29
16
71
8
63

66
57
55
64
70
74
93
94

57
42
36
37
40
21
69
100

EXPERIMENTS WITH SHEEP.

* Pasture grass

75

73

65

76

80

Meadow hay (very good)

64

65

54

65

63

Meadow hay (ordinary)
Red clover hay

59
56

57
56

51

58

62
61

56
49

Lucerne hay (very good)

59

71

41

66

45

*0ats

71

80

83

76

30

*Beans

90

87

84

91

79

* Maize

89

79

85

91

62

On comparing these figures it is evident that a horse
digests meadow grass and hay less perfectly than a sheep,
and the difference between them is apparently as great
when the food is young grass as when ordinary hay is
employed. There is little difference in the proportion of
albuminoids assimilated by the two animals, but the
divergence becomes considerable when we come to the
carbo-hydrates, fibre, and fat. Of the carbo-hydrates the

DIGESTIBILITY OF POODS. 101

horse digests 7 — 10 per cent., of the fibre 21 per cent.,
and of the fat and waxy matter 24 — 52 per cent, less
than the sheep. On the whole, the horse digests about
12 per cent, less of the total organic matter of grass hay
than the sheep. With red clover hay the results with the
horse are better. With lucerne hay of good quality the
digestion by the horse is still better, and (save as regards
the fat) practically equals that of the sheep.

The smaller digestive power of the horse for vegetable
fibre is plainly connected with the fact that it is not like
the sheep a ruminant animal, and is thus unprovided with
the same means of attacking an insoluble food. In a
trial with wheat- straw chaff the horse digested 22*5,
and the sheep 47*6 per cent, of the total organic
matter.

With corn the digestion of the horse is apparently
quite equal to that of the sheep. No stress must, of
course, be laid on the digestion coefficients found for
ingredients of the food present in small quantity, as the
fat and fibre of beans, and the fibre of maize. In French
experiments on horses, in which maize or beans were
consumed alone, without the addition of hay, it was found
that with maize 94'5 per cent, of the total organic matter,
and 87*1 per cent, of the nitrogenous substance, and with
beans 90*4 per cent, and 89*3 per cent, respectively,
were digested.

Of potatos 93 per cent., and of carrots 87 per cent,
of the organic matter were digested by the horse.

3. Experiments with Pigs. — These have not been so
numerous as those with ruminant animals. The following
table shows the digestibility ascertained for some of the
common pig foods : —

102

THE CHEMISTRY OP THE FARM.

EXPERIMENTS WITH PIGS.

Digested for 100 supplied.

Food.

Total

Nitro-

Soluble

organic

genous

Fat.

carbo-

matter.

substance.

hydrates.

*Sour milk

97

96

95

99

*Meat flour

95

97

87

—

Pea meal

91

88

49

96

*Bean meal

84

79

71

91

Barley meal

83

78

68

90

Maize meal

92

86

76

9

Rye bran

67

66

58

75

Potatos

94

81

~~~

98

The digestive power of the pig for the foods here men-
tioned is very considerable, and in cases admitting of
comparison appears to be fully equal to that possessed by
ruminant animals. Nor is the pig incapable of digesting
vegetable fibre, when this is presented in a favourable con-
dition. Two pigs fed on green oats and vetches digested
48*9 per cent, of the fibre supplied. The digestive ap-
paratus of a pig is not, however, adapted for dealing
successfully with bulky fodder. Pigs are very capable of
digesting animal food, as will be seen from the results
obtained with milk and meat flour quoted in the table.

4. Experiments with Geese and Fowls. — Birds have
apparently no power of digesting vegetable fibre; the
food passes too quickly through the system for the fibre
to be attacked.

Circumstances affecting Digestibility.— The indi-
vidual character of the animal undoubtedly affects the
proportion digested. Of two animals supplied with the
same food, one will often persistently digest a larger pro-
portion than the other. In young animals the digestive
* The numbers in this case were obtained from a single sample of food.

CIRCUMSTANCES AFFECTING DIGESTIBILITY.

103

power is apparently equal to that of animals of full age.
Sheep from six to fourteen months old showed no distinct
change in digestive capacity.

Differences in the quantity of the daily ration of hay do
not sensibly affect the proportion digested ; an animal will
not digest more by being starved. Labour is also prac-
tically without influence ; horses at rest and at work digest
nearly the same proportion of their food. The cooking
of food is generally of doubtful advantage ; beans, maize,
and bran are not better digested by horse or ox when
previously soaked in water. Barley, maize and pea
meal have been found more nourishing for pigs when fed
dry than when previously cooked. Differences in the
quality of a food may, however, exercise a great in-
fluence on its digestibility : the addition of another food
may also considerably alter the rate of digestion of the
first food.

The digestibility of fodder plants is mainly determined
by their age ; all the constituents of a young plant are
more digestible than in the same plant of greater age.
The composition of meadow grass cut at three different
dates has been already given on page 93 ; the three
cuttings were supplied to sheep in the form of hay, and
the following digestion coefficients were obtained : —
DIGESTION OF HAY BY SHEEF.

Date of cutting.

Proportion of each constituent digested for
100 supplied.

Total
organic
matter.

Nitro-
genous
substance.

Pat.

Soluble
carbo-
hydrates.

Fibre.

May 14 ...
June 9 ...
„ 26 ...

75-8
64-3
57-5

73-3
72-1
55-5

65-4
51-6
43-3

75-7
61-9
55-7

79-5
65-7
61-1

104 THE CHEMISTEY OF THE FAKM.

The diminution in digestibility with the increasing
maturity of the grass is very striking, and is very equally
spread over all the constituents. Experiments with clover
cut at different stages of growth have yielded similar
results.

It follows from what has now been stated that no fixed
nutritive value can be ascribed to fodder crops, or to the
hay made from them, as both their composition and
digestibility are largely influenced by their age and
condition when cut. The young plant is always the most
nutritive. The superior fattening quality of a pasture,
as compared with that of the hay made from it, is clearly
due to the fact that on land continuously grazed the
animal is entirely fed on young herbage, while hay
will always consist of the fully grown plant. Fur-
ther illustrations of the different digestibility of hay
of various qualities have been already given on page
100.

Fodder crops do not sensibly diminish in digestibility
by being made into hay, if haymaking is carefully carried
out in good weather. But the loss of the finer parts of
the plant by rough treatment, or the washing out of
soluble matter by rain, may considerably diminish the
digestibility. Hay appears to lose some of its digesti-
bility by keeping.

Influence of one food on the digestion of another. —
If to a diet of hay and straw, consumed by a ruminant
animal, a pure albuminoid, as wheat gluten, be added,
the added food is entirely digested without the rate of
digestion of the original food being sensibly altered.
The same result has been obtained in experiments
with pigs fed on potato s, to which variable quantities

CIECUMSTANCES AFFECTING DIGESTIBILITY. 105

of meat flour were afterwards added: the albumi-
noids of the meat were entirely digested, while
the proportion of the potatos digested remained un-
changed.

An addition of oil (olive, poppy, and rape oil) to a diet
of hay and straw is also apparently without unfavourable
influence on the rate of digestion ; indeed some experi-
ments with small quantities of oil (Jib. of oil per day per
1,000 Ibs. live weight) show an improved digestion of the
dry fodder. Oil supplied in moderate quantities is itself
entirely digested.

An addition of starch or sugar to a diet of hay or
straw will, on the contrary, diminish its digestibility, if
the amount added exceeds 10 per cent, of the dry fodder.
The albuminoids of the food suffer the greatest loss of
digestibility under these circumstances; the fibre also
suffers in digestibility if the amount of carbo-hydrate
added is considerable. When starch has been added, it
is itself completely digested, if the ratio of the nitro-
genous to the non-nitrogenous constituents of the diet
(seepage 111) is not less than 1 : 8.

These facts are of considerable practical importance.
Nitrogenous foods, as oilcake and bean meal, may be given
with hay and straw chaff without affecting their digesti-
bility ; but foods rich in carbo-hydrates, as potatos and
mangels, cannot be given in greater proportion than 15
per cent, of the fodder (both reckoned as dry food) with-
out more or less diminishing the digestibility of the latter.
This decrease in digestibility may, however, be counter-
acted in great measure by supplying with the potatos
or mangels some nitrogenous food. When this is done
the proportion of roots or potatos may be double that just

106 THE CHEMISTRY OP THE FARM.

mentioned without a serious loss of digestibility. Potatos
exercise a greater depressing effect on the digestibility
of hay than roots, starch being more potent in this respect
than sugar. The cereal grains are rich in starch, but
contain also a fair proportion of albuminoids ; they may
be added to dry fodder without seriously affecting its
digestibility, if the ratio of the nitrogenous to the
non-nitrogenous constituents of the diet does not fall
below 1:8.

Common salt is well known to be a useful addition to
the food of animals. It is stated to quicken the conver-
sion of starch into sugar by the saliva and pancreatic juice.
When sodium salts are deficient in the food, salt supplies
the blood with a necessary constituent. Sodium salts
are tolerably abundant in mangels, and small in quantity
in hay ; they are absent in potatos, and generally absent
in grain of all kinds.

Comparative Nutritive Value of Poods.— Having
made ourselves acquainted both with the composition,
and the degree of digestibility of ordinary cattle foods,
we are now in a position to enter on some general consider-
ations as to their relative feeding value. The following
table shows the quantity of digestible nutritive matter
in 1000 Ibs. of ordinary foods when supplied to sheep or
oxen. The carbo-hydrates in the table include digestible
cellulose. In calculating the amount of digestible albu-
minoids it has been assumed that in the original diges-
tion experiment the amides and nitrates present, being
soluble bodies, have been reckoned as digestible
albumin.

COMPARATIVE VALUE OF FOODS.

107

DIGESTIBLE MATTER IN 1000 LBS. OF VARIOUS FOODS.

Total
organic
matter.

Nitrogen-
ous sub-
stance.

Fat.

Carbo-
hydrates

Albumi-
noids.

Ibs.

Ibs.

Ibs.

Ibs.

Ibs.

Cotton cake (decorticated)

683

374

119

190

343

Linseed cake

648

232

103

313

216

Peas

745

199

15

531

172

Beans

728

224

14

490

193

Oats

597

102

50

445

94

Barley

660

82

20?

558

75

Maize

774

82

43

649

75

Rice meal

712

92

106

476

84

Wheat bran

569

113

28

428

91

Malt dust

716

193

11

512

127

Brewers' grains

136

36

9

91

35

Pasture grass

137

26

5

106

17

Clover hay (med um)

444

68

11

365

47

Meadow hay (medium)

474

55

12

407

41

Barley straw

435

7

6

422

4

Wheat straw

377

5

4

368

Potatos

227

17

1

209

9

Carrots

131

13

2

116

7

Mangels

111

11

1

99

4

Swedes

101

14

2

85

7

Turnips

73

10

2

. 61

5

The figures in this table will be found useful in
arranging the rations for farm animals ; the figures can,
however, only approximate to the truth, as with different
qualities of the same food, and different animals, some-
what different quantities of matter will be digested. The
figures given for carrots, mangels, swedes and turnips
are rather too high, as they have been assumed to be
entirely digested.

1. Capacity of different Foods for producing Heat
and Work. — The only basis on which the nutritive value
of foods of different composition can be compared is in
respect to their capacity for producing heat. The pro-

108 THE CHEMISTRY OF THE FARM.

duction of heat and mechanical work is the principal
result which food accomplishes in the animal body ; the
capacity for producing heat is also intimately related to
the capacity for producing fat. On the other hand, the
amount of heat which any food is capable of producing
stands in no relation to its power of increasing or renew-
ing the nitrogenous tissues of the body. We may, how-
ever, safely assert that the amount of heat generated by
the combustion of the digestible constituents of any food
will be a fair guide to its nutritive value, when the diet
of which it forms a part supplies a sufficient amount of
digestible albuminoids, and this will be the case whenever
foods are skilfully employed.

According to recent determinations of the heat- pro-
ducing power of the various food constituents, their com-
parative values in this respect are : —

Fat 229

Albumin . ... . . .107

Starch 100

Cane Sugar and Gum .... 97

Glucose and Milk Sugai- .... 90

Cellulose (about) 86

Asparagine 49

The albumin and asparagine are here reckoned as
minus the nitrogenous matter (urea) excreted by the
kidneys.

If we take the quantities of digestible fat, albu-
minoids, amides, carbo-hydrates, and cellulose, supplied
by any food, and multiply them by their respective heat
coefficients, the sum of the products will represent the
heat-producing capacity of the food when consumed

COMPARATIVE VALUE OF FOODS.

109

in the animal body. Taking the heat-producing

capacity of cotton cake, calculated in this manner, as

100, the values found for other foods will be as
follows : —

COMPARATIVE HEAT-PRODUCING- VALUE OF FOODS.

Ordinary
condition.

Perfectly dry.

Cotton cake (decorticated)

100

100

Maize ....

97

100

Rice meal ...

94

96

Linseed cake ...

93

97

Peas ....

90

96

87

93

Barley ....

80

85

Malt dust ...

80

81

Oats ....

78

83

Wheat bran .

69

73

Meadow hay (medium) .

51

55

Clover hay (medium)

48

53

Barley straw ...

46

49

Wheat straw ...

40

43

Potatos ....

26

95

Brewers' grains

16

G4

The correctness of these figures mainly depends upon
the digestibility of the respective foods being as shown in
the experiments with ruminant animals described in the
last section. Linseed cake, from the large proportion of
fat and albuminoids which it contains, would be expected
to occupy a higher position in the table than maize ; its
lower rank is due to its less perfect digestibility. The
table on page 97 shows, that while 19 per cent, of the
organic matter of linseed cake remain undigested, and
therefore useless to the animal, only 11 per cent, of
maize are thus wasted. If the linseed cake were

110 THE CHEMISTRY OP THE FARM.

richer in fatty matter it would occupy a higher place in
the table.

We should conclude from these calculations that an
equal weight of dry food, as maize, peas, or oil -cake will
have a nearly similar feeding value if supplied to an
animal receiving a sufficient amount of albuminoids in its
diet, as, for example, if given to a sheep fed on good
meadow or clover hay.

Many foods may, in fact, be substituted for each
other without injury to the nutritive value of the whole
diet. A farmer should thus be able to introduce economy
into his feeding by watching the market, and making use
of those foods which are cheapest. In making his
selection, the manure value of the food must, however,
be taken into account.

2. Proportion of Albuminoids to Non- Albuminoids. —
A point of considerable importance in determining the
suitability of a food as an article of diet is the proportion
between the digestible albuminoid and the digestible
non-albuminoid organic constituents: this relation is
most conveniently termed the ' ' albuminoid ratio " of the
food. Before calculating this relation, the non-albuminoid
ingredients of the food are first reduced to their equiva-
lent in starch.* Taking the average composition of
foods already given, and the digestibility of their con-
stituents shown by the German experiments, the albu-
minoid ratios will be as follows : — •

* It has been usual to multiply the fat by 2 '5 to obtain its equivalent in starch
and to add the product to the digested carbo-hydrates and fibre to obtain the total
non-albuminoid nutritive matter. In the following table the fat has been multi-
plied by 2'3, and the carbo-hydrates (and in the second column the amides) re-
duced to their approximate equivalent in starch, according to the relations shown
on p. 108.

THE ALBUMINOID EATIO.

Ill

RELATION OF NITROGENOUS TO NON-NITEOGENOUS CON-
STITUENTS IN THE DIGESTIBLE PART OF FOOD.

Total nitrogenous
substance to
non-nitrogenous.

Albuminoids
to
non-albuminoids.

Cotton cake, decorticated
Cotton cake, undecorticated .
Linseed cake ....
Beans
Brewers' grains
Peas

1 1-2
1 2-1
1 2-3
1 2-3

1 2-8

1 2-8

1 : 1-4

1 2-4
1 2-6
1 2-7
1 2-9
1 3-3

Malt dust ....
Wheat bran ....
Oats

Pasture grass ....
Clover hay (medium)

1 2-6
1 4-2
1 5-4
1 4-0
1 5-0
1 7-3

1 4-2
1 5-3
1 5-9
1 6-4
1 7-5
1 8-0

Rice meal ....
Meadow hay (medium) .
Maize
*Swedes
* Turnips

1 7-6
1 6-9
1 9-0
1 5-4

1 5-8

1 8-4
1 9-5
1 9-9
1 11-5
1 12-1

* Carrots .....
fPotatos

1 8-6
1 12-2

1 16-5
1 23-5

1 8-6

1 24-1

Barley straw ....
Wheat straw ....

1 53-8
1 65-9

1 108-0
1 ?

In the first column the whole of the nitrogen in the
food is reckoned as existing as albuminoids ; this suppo-
sition, though erroneous, is the one most usually made in
calculating the albuminoid ratio. In the second column
the true albuminoids only are taken account of ; we shall
employ these latter ratios in the present work. In this
column the amides have been reckoned among the non-
albuminous constituents.

* The whole of the root is here assumed to be digestible,
f The quantity of digestible constituents is taken from thei experi-
ments with pigs.

112 THE CHEMISTEY OP THE PAEM.

The figures show in a striking manner the wide differ-
ences that exist amongst foods as to the proportion of
albuminoids which they supply. The differences are in
fact far greater than was formerly supposed, when it was
customary to assume that the whole of the nitrogen of
food was albuminoid. Mangels now appear as a food
very poor in albuminoids, whereas they were formerly
supposed to contain a sufficient proportion. The poverty
of a diet of roots and straw chaff in digestible albumin-
oids is the true reason of the excellent effects produced
by the addition of oil-cake or leguminous corn. Oil-
cake, peas, and beans, used under these circumstances,
have an effect far above their own intrinsic feeding value,
as their presence raises the character of the whole diet,
and enables the carbo-hydrates of the roots and straw to
contribute to the formation of carcase. If, on the other
hand, an animal is at pasture, or fed with clover hay, and
is thus receiving an abundance of albuminoids, the use
of oil-cake or beans will be without especial advantage to
the animal, and they may be economically replaced by
maize or other cereal grains.

It should be recollected that the albuminoid ratio of a
food may be different for different animals if their powers
of digestion are unequal. Thus the same meadow hay
supplied to sheep and horses had for the former an albu-
minoid ratio of 1 : 9*1, and for the latter a ratio of 1 : 6*7.
The horse, as we have seen, digests the nitrogenous con-
stituents of hay nearly as well as the sheep, but fails in
digesting the non-nitrogenous constituents. Hay is thus
a more nitrogenous food for horses than for sheep.

The proportion of albuminoids most suitable for various
diets will come under consideration in the next chapter.

COMPARISON OF FOODS. 113

3. Influence of proportion of Water. — The feeding
value of roots, and of other foods rich in water, is often
diminished by the fact that a part of the heat they pro-
duce in the body is consumed in raising the water they
s apply to the temperature of the animal, and of vaporis-
ing a part of it as perspiration. With sheep the normal
proportion of water to dry food is about 2:1; with
horses 2 — 3 : 1 ; with cattle about 4:1. An excess of
water produces a waste of food.

A sheep feeding on turnips in winter in the open field,
consuming, say, 20 Ibs. of roots per day, will receive in
its food about 1 8 Ibs. of water, of which 14 Ibs. is beyond
that necessary for nutrition. This 14 Ibs. of water has
to be raised from near the freezing point to the tempera-
ture of the animal body, a rise of at least 60° Fahr. To
warm the water to this extent will require the combus-
tion of about 51 grams of carbo-hydrates, (reckoned as
starch,) equal to about 8 per cent, of the total food con-
sumed. The actual waste of food will however greatly
exceed this, as a part of the extra water will be exhaled
as vapour in the breath and perspiration, and to vaporise
1 Ib. of water at the temperature of the animal body
requires the combustion of 64 grams of starch.

The consumption of an excess of water will also some-
what increase the amount of albuminoids oxidised in the
animal body, and thus occasion a waste of the nitrogenous
part of the food.

The economy of supplying sheep on roots or green
fodder with dry food in addition, is obvious from the facts
just stated ; by so doing the quantity of water consumed
by the animal is diminished, and its proportion in the diet
brought more nearly to a normal ratio.

114 THE CHEMISTRY OF THE FARM.

4. General Conclusions. — Attempts have often been
made to affix a money value to each of the constituents of
food, and having done this, to calculate the money value of
any food on the basis of its composition. Calculations of
this kind can at any time be made on the basis of the mar-
ket prices, but values thus arrived at are naturally variable,
and by no means necessarily represent the value of the
food to the animal, or its value as a source of manure.
The relative nutritive value of the various constituents of
food can be estimated on scientific grounds only on the
basis of their respective heat-producing powers (p. 109) ;
from this point of view fat has more than twice the value
of any other food constituent. If, however, the value of
food constituents is to include (as it must in practice)
their manure value, the nitrogenous substance will then
become of greatest worth. The manure value is at
present scarcely taken into account in determining the
market price of food.

It is difficult, however, to affix a definite feeding value
to any food, as its practical effect must depend in great
measure on the conditions under which it is employed ;
more especially on the kind of animal consuming it, and
the general character of the diet of which it forms a part.
Thus the value of a bulky food, as hay or straw, is far
greater when given to a ruminant animal than when con-
sumed by ahorse or pig. Concentrated, easily digestible
foods, as corn and oil-cake, have clearly a value above
their composition when added to a poor and bulky food,
as straw chaff, or to a watery food like turnips, because
they are the means of raising the quality of the diet to a
point at which the animal will thrive. On the other hand,
roots and green fodder, even when watery and poor in

POODS. 115

composition, may have a considerable effect when added
in moderate proportion to dry food. The highest value is
in short only obtained from food when it is skilfully
employed.

There is finally a condition which we can never hope
to express by figures, but which has a considerable influ-
ence on the effect of any diet ; this is flavour. An agree-
able flavour stimulates appetite, and probably promotes
digestion. This part of the question belongs, however,
rather to practice than science.

CHAPTER VIII.

RELATION OP FOOD TO ANIMAL REQUIREMENTS.

T7ie Requirements of the Young Animal. — Composition of colostrum
and milk — Suitable albuminoid ratio of the food — Importance of
ash constituents. The Adult Animal. — Production of Heat —
Production of Work — Maintenance diets — Labour diet. The Fatten-
ing Animal. — Conditions necessary for increase— Results obtained
when fattening oxen, sheep, and pigs, on ordinary diets — Altera-
tions in consumption of food, and rate of increase, as fattening
proceeds — Albuminoid ratios for fattening animals. Production of
Wool. — Composition of wool — Influence of diet. Production of
Milk. — Influence of diet on the quantity of the milk — Albuminoid
ratio for milk-cows — Comparative yield of nitrogenous produce by
cow and ox — Influence of diet on the quality of milk and butter.

The Young Growing Animal. — The special character
of the nutrition of young animals is the rapid formation
of nitrogenous tissue and bone, for which purpose an
abundant supply of albuminoids and ash constituents in
the food is clearly requisite.

The kind of food most appropriate to the wants of a
young animal is shown by the composition of milk. The
milk supplied to the young immediately after birth (the
colostrum) is of a very concentrated description. During
the first week after birth the quantity of the milk greatly
increases, and its composition gradually alters from that
of colostrum to that of ordinary milk.

In the following table will be found the composition
of the colostrum and milk yielded by various animals ;
the numbers given are the mean of many analyses.

FOOD OF YOUNG ANIMALS.
COMPOSITION OF COLOSTRUM.

117

Water.

Albumi-
noids.

Fat.

Sugar.

Ash.

Albuminoid
ratio.

Ewe

66-4

16-6

10-8

5-0

1-2

1 : 1-8

Sow

70-1

15-6

9-5

3-8

09

1 : 1-6

Cow

71-7

20-7

3-4

3-2

1-1

1 :0-5

COMPOSITION OF MILK.

Ewe

81-3

6-3

6-8

4-8

0-8

1 3-1

Sow

84-6

6-3

4-8

3-4

0-9

1 :>2

Cow

87-0

3-7

3-9

4-7

0-7

1 3-6

Human

87-0

2-4

3-9

6-2

0-5

1 6-1

Goat

87-3

3'5

3'9

4-5

0'8

1 3-7

Ass

89-6

2-2

1-6

6-1

0'5

1 4-2

Mare

90-2

1*9

1-1

6-4

0-4

1 4-4

The colostrum is characterised by an especially high
percentage of albuminoids. In milk we find a smaller
proportion of albuminoids and a much larger proportion
of sugar.

The solid matter of milk has a very high feeding
value, owing to the large proportion of fat and albumi-
noids present and its perfect digestibility. If we
take, as before, the heat-producing capacity of dry cotton
cake as 100, then the heat-producing capacity of dry
cow's milk will be 143. Milk also supplies the ash
constituents necessary for the formation of bone and
tissue: 1 00 Ibs. of cow's milk will supply about 0*20 Ib.
of phosphoric acid, 0*17 Ib. of lime, and 0*17 Ib. of
potash.

The relation of the nitrogenous to the non-nitro-
genous constituents of milk is much higher than in most
v 3getable foods ; the analyses in the table show a rela-

118 THE CHEMISTRY OP THE FA.RM.

tion varying from 1 : 2'2 to 1 : 6'1, and in colostrum
the relation is still higher. In supplying very young
animals with artificial food the above facts must be
borne in mind ; the food should clearly be of an easily
digestible character, and contain a considerable propor-
tion of albuminoids and fat. Instead of this, foods rich in
starch are too often employed. Linseed is, of ordinary
foods, the one most similar to milk in composition.

As the animal grows the quantity of food it requires
increases, at the same time a larger proportion of the food
is applied to the production of heat and mechanical work :
the proportion of nitrogenous matter in the food may
therefore gradually be diminished, carbo-hydrates and fat
being quite as fit as albuminoids for producing heat and
work. Under natural conditions this diminution in the
nitrogenous character of the diet soon takes place, the
animal daily taking more and more grass in addition to
its mother's milk. The albuminoid ratio of the diet of
young rapidly growing animals may vary from 1 : 5 to
1 : 7, the more nitrogenous diet being that most suitable
for younger animals, or for the production oc more rapid
increase.

It is very important that the food supplied to young
animals should contain a sufficient amount of ash con-
stituents, and especially of lime : see p. 92.

The Adult Animal. — The food of an adult animal,
not fattening, is employed for the renovation of the
tissues, the formation of hair, wool, &c., and for the
production of heat and mechanical work; by far the
greater portion of the food is applied to the production
of heat.

PRODUCTION OF HEAT AND WORK. 119

Production of Heat. — In the case of an animal at
rest, not gaining in weight, the final results of the
digested food will almost wholly appear as heat and
excrementitious matter.

The smaller the animal the larger is the production
of heat per unit of weight. Thus a full-grown dog,
weighing 6 Ibs., was found to produce twice as much
heat per unit of weight as one weighing 40 Ibs. This is
due to the fact, that small bodies have, in proportion to
their weight, a much greater surface than large bodies,
and consequently suffer more by cooling. Small animals
thus stand in special need of a liberal diet.

Production of Work. — The work performed by an
animal is partly internal and partly external. The
internal work consists in the muscular movements which
produce circulation, respiration, and other vital pro-
cesses ; such work is carried on even when the animal
is at rest. In man the whole of the blood is pumped
through the heart every half minute. The daily work
performed by the heart of an average man has been
calculated as equal to 150 — 200 foot-tons ; that is to
say, the power exerted by the heart would raise 1 ton
to the height of 150 — 200 feet* The work performed
by other organs, and by the muscles when merely
maintaining the body in an erect position, must be very
considerable, but has not yet been satisfactorily meas-
ured. Nearly the whole of the internal work is finally
resolved into heat.

As external work we may take as an example a walk
of 20 miles on level ground ; this to a man of 11 stone
weight (154 Ibs.) will represent an exertion equivalent

120 THE CHEMISTEY OF THE FABM.

to about 363 foot-tons. During hard work, about one-
sixth of the total energy developed in a man's body may
appear as external work, the rest will appear as heat.

It was formerly supposed that muscular force wag
produced by the oxidation of the nitrogenous constituents
of muscle, and that a diet rich in albuminoids was
necessary if hard labour was to be maintained. This
idea is now known to be erroneous, it having been shown
by repeated experiments that labour does not necessarily
increase the production of urea, while it does in every
case greatly augment the amount of carbonic acid exhaled.

The energy required for work may be produced in
the body by the oxidation of albuminoids, but it may
equally be generated by the oxidation of fat or carbo-
hydrates. The animal body has been compared to a
steam engine, in which food is burnt in place of coal.

When labour is demanded from an under-fed animal,
the oxidation taking place may be in excess of the food
supplied ; in such a case the fat and albuminoids of the
animal tissues are oxidised, and the excretion of urea
becomes increased. A working animal ill supplied with
food will thus suffer seriously in condition.

When an animal " out of training " is suddenly called
upon to perform hard work, it will at first show an in-
creased oxidation of albuminoids as the result of labour ;
but this will cease as the body becomes fit for work, if
sufficient food is supplied. Daring training for in-
creased work an albuminous diet will be necessary, as
the muscular apparatus has to be built up.

Maintenance Diets. — In the case of an adult animal
not increasing in weight, and performing a minimum

MAINTENANCE DIETS. 121.

amount of work, as, for instance, a horse or ox in a
stable, the quantity of food required is reduced to its
smallest limits. A horse of 1000 Ibs. weight, at perfect
rest, will require, according to the German experiments,
8'4 Ibs. per day of digestible organic matter (reckoned as
starch) to maintain its condition. The French experi-
menters found 7'2 Ibs. sufficient. In their case 70 per
cent, of the food was corn, while in the German experi-
ments 42 per cent, was corn, and the rest hay and straw
chaff. An ox of 1000 Ibs. live weight, quiefc in the stall,
will require daily, according to the German experiments,
about 0*5 — 0*6 Ibs. of digestible albuminoids,* and 7*3 —
8*4 Ibs. of digestible non-albuminous food, reckoned as
starch, to preserve its condition.f With sheep the main-
tenance diet must be more liberal, as in their case the
growth of wool, with its accompanying fat, is always in
progress, and is practically independent of the abundance
or poverty of the diet. For 1000 Ibs. live weight (shorn),
sheep fed on meadow hay will require about I'O Ib. of
digestible albuminoids,* and 10'8 Ibs. of digestible non-
albuminous food, or 16 — 17 Ibs. of dry organic matter,
per day, to preserve their condition. If fed on mangels
and straw chaff the quantity of dry organic matter must
be raised to 20 — 25 Ibs. In these maintenance diets for
adult animals the albuminoid ratio of the food is but

* These numbers represent true albuminoids, and are, therefore
smaller than the German figures.

f In these experiments the food was chiefly hay or straw. By feed-
ing with maize meal only, and keeping the cattle in a warm stable, the
digested albuminoids have been reduced to O4 Ib., and the non-albumi-
noids, reckoned as starch, to 3-7 Ibs. per day. The economy of this
American system probably depends on the much smaller amount of
water drunk by the animal with this less bulky food.

122 THE CHEMISTRY OF THE FARM.

1 : 14 in the case of the ox, 1 : 1 1 in the case of the sheep
fed on hay, and the relation is wider still in the case of
the sheep fed on straw and mangels. It is advisable that
a minimum amount of nitrogenous matter should be
given, as any excess over that absolutely demanded pro-
motes waste in the system.

Labour Diet. — If external work is to be performed,
the body weight remaining unaltered, the quantity of
food must be considerably increased, and the food must
be of such quality that it may be possible to digest a
sufficient amount in the required time. A man doing a
fair day's work was found to exhale one-third more
carbonic acid than when at rest ; a man doing such work
would clearly require one-third more food to maintain
the same condition of body. According to Wolffs ex-
periments, 1251 foot-tons of work may be obtained from
a horse, without altering its body weight, for each pound
of digestible organic matter, reckoned as starch, con-
sumed over and above the maintenance diet. Wolff
found, as has been already mentioned, that it is indifferent
whether this extra food is supplied by albuminoids or
carbo-hydrates.

The relative value of the principal constituents of
food for the production of heat and work will be found
on p. 108, and the relative value of different foods on
p. 109. The value of foods containing cellulose is for the
horse somewhat less than that shown in the table.

In constructing a labour diet for horses it is well to
combine bran with beans or oats, but not with maize, as
both bran and maize are somewhat laxative.

PEOCESS OF FATTENING. 123

The Fattening Animal.— For the body to increase in
weight ifc is clear that the food supplied must be in excess
of the quantity demanded for mere renovation of tissue,
and for the production of heat and work. When such an
excess of food is given, a part of the albuminoids and ash
constituents is generally converted into new tissue, while
a part of the fat, carbo-hydrates, and albuminoids is stored
up in the form of fat.

As only the excess of the food is converted into increase,
liberal feeding is, within certain limits, the most econo-
mical. If a lamb can be brought by liberal treatment to
150 Ibs. live weight at one year old, the amount of food
consumed will be far smaller than if two years are occupied
in attaining the same weight, for the food required for
animal heat and work during the second year is clearly
saved.

Economy of food is also promoted by diminishing the
demand for heat and work. An animal at rest in a stall
will increase in weight far more than an animal taking
active exercise on the same diet. In the same way the
increase from a given weight of food will be less in winter
than in spring or autumn, a far larger proportion of the
food being consumed for the production of heat when the
animal is living in a cold atmosphere. Hence the economy
of feeding animals under cover during winter. If, however,
the temperature becomes so high as to considerably in-
crease the perspiration, waste of food again takes place,
heat being consumed in the evaporation of water. The
temperature most favourable for animal increase is appa-
rently about 60P Fahr. Quietness, and freedom from
excitement, are essential to rapid fattening ; the absence of
strong light is therefore desirable.

124

THE CHEMISTRY OF THE FABM.

The capacity of an animal for fattening depends much
on breed and temperament. A farmer learns to recognize
the fattening disposition of an animal from the feel of its
skin, etc.

The three animals with which the farmer is chiefly con-
cerned have very different powers of consuming food, and
yield different rates of increase. Lawes and Gilbert reckon
that, on an average of the whole fattening period, an ox
will produce 100 Ibs. of live weight from the consumption
of 250 Ibs. oilcake, 600 Ibs. clover hay, and 3500 Ibs. swedes.
Sheep will produce the same increase by the consumption
of 250 Ibs. oilcake, 300 Ibs. clover hay, and 4000 Ibs.
swedes.* Pigs will require about 500 Ibs. of barley meal
to yield a similar result. Taking these data, the rate of
food consumed, and of increase yielded, will be as
follows : — •

KESULTS OBTAINED WITH FATTENING ANIMALS
PER 100 LBS. LIVE WEIGHT PEE WEEK.

Beceived by the
animal.

Results produced.

Food

Total
dry food.

Digestible
organic
matter.

consumed
for heat
and

Dry

Manure
produced}:

Increase
in live
weight.

work.f

Ibs.

Ibs.

Ibs.

Ibs.

Ibs.

Oxen. . .

12'5

8-9

6-86

4-56

1-13

Sheep

16-0

12-3

9-06

5-10

1-76

Pigs ....

27-0

22-0

12-58

6-27

6-43

PROCESS OF FATTENING.

125

EESULTS OBTAINED IN RELATION TO FOOD CONSUMED.

Increase in live
weight.

On 100 Ibs. of dry food.

Per

100 Ibs.
dry food.

Per

100 Ibs.
digested
organic
matter.

Consumed
for heat
and
work.f

Dry

Manure
produced^

Dry

Increase
yielded.

Ibs.

Ibs

Ibs.

Ibs.

Ibs.

Oxen ....

9-0

12-7

54-9

36-5

6-2

Sheep . . .

11-0

14-3

56-6

31-9

8-0

Pigs ....

23-8

29-2

46-6

23-2

17-6

It is evident from the upper division of the table that
pigs are able to consume far more food in proportion to
their weight than either sheep or oxen. This is due to
the concentrated and digestible character of the food
(corn meal) supplied to a fattening pig, and to the great
capacity of this animal for assimilation. The proportion
of stomach is greater in a fat ox or sheep than in a pig,
being on 100 Ibs. live weight, 3*2 for the ox, 2*5 for the
sheep, and 0*7 for the pig. On the other hand, the
proportion of the intestines is greater with the pig than
with sheep or oxen. Euminant animals are thus best
fitted for dealing with food requiring a prolonged diges-
tion, while the pig excels in the capacity for assimilation.
As a natural result of the larger consumption of food,
the pig increases in weight much more speedily than
either the sheep or ox ; but not only is the rate of
increase more rapid, the increase yielded by the pig is
also far greater in proportion to the food received, as

* Since these estimates were made the fattening capacity of both sheep
and oxen has apparently increased, owing to improvements in the breeds.

f In calculating the amount of food consumed for the production of
heat and work, it has been assumed that the fat in the increase has been
derived from the fat and carbo-hydrates supplied by the food.

J Dry matter of solid excrement and urine, exclusive of litter.

126 THE CHEMISTRY OF THE FARM.

plainly appears from the lower division of the table. The
pig, with its very large consumption of food, has, in fact,
to spend a smaller proportion of it on heat and work, and
has thus a larger surplus left to store up as increase. Of
100 Ibs. digested organic matter, the fattening ox spends
about 77 for heat and work, the sheep 74, and the pig 57.
The upper division of the table shows, however, that in a
given time and for the same body weight, the pig appro-
priates a larger amount of food to heat than the sheep, and
the sheep more than the ox. This is probably due to the
greater loss of heat from the bodies of small animals (see
p. 119), which in the pig is intensified by the slight cover-
ing of hair upon its skin. The pig, with its rapid feeding,
and high rate of increase, is undoubtedly the most econ-
omical meat-making machine at the farmer's disposal.

The results given by sheep are seen to lie in nearly
every case between those given by oxen and pigs, being
however much nearer to the former than to the latter.
The German experiments place the sheep below the ox
as an economic producer of increase, instead of above it,
as in the Rothamsted statistics just quoted ; the difference
is probably due to the different breeds of animals experi-
mented with. The results relating to manure will be
discussed in the next chapter.

We have hitherto looked at the fattening period as a
whole ; the rates of consumption and of increase are, how-
ever, very different in different stages of this period.

As a fattening animal increases in size the quantity
of food it consumes also somewhat increases, the stomach
at the same time becomes larger. When the animal
becomes very fat the consumption of food falls off again,
and the rate of increase at this point is much diminished.

PROCESS OP FATTENING.

127

As fattening advances the daily increase in live
weight becomes gradually smaller, and the same amount
of food will produce a steadily diminishing amount of
increase. This is partly because the increase during the
later stages of fattening is drier, and contains a larger
proportion of fat than in the earlier stages of the pro-
cess. Partly also because the consumption of food for heat
and work is increased with the increasing size of the
body. More internal work must also be performed to
add increase to a large animal than to a small one.
These changes in the rates of consumption and increase
are seen more strikingly in the case of pigs than with
other animals, from the greater rapidity of the fattening
process. The following table shows ths average results
obtained on sixteen pigs fattened at Rothamsted at the
same time, the food being 7 Ibs. of pea meal per head
per week, with an unlimited supply of barley meal.
The pigs had an average weight of 135 '8 Ibs. when put
up to fatten : at the end of ten weeks their average
weight had become 276*3 Ibs.

FATTENING PIGS— WEEKLY CONSUMPTION OF FOOD AND
RATE OF 1NCEEASE.

First fortnight .
Second do. . . .
Third do.
Fourth do. . . .
Fifth do.

Mean . . . .

Food consumed.

Increase in live
weight.

Food
pro-
ducing
100 Ibs.
of in-
crease.

Per
head.

Per

100 Ibs.
live
weight.

Per

head.

Per

100 Ibs.
live
weight.

Ibs.
60-1
67-5
66-4
66-0
69-6

Ibs.
39-7
36-7
30-9
27-4
26-3

Ibs.
15-5
17'4
13-2
12-9
11-3

Ibs.
10-3
9-4
6-2
5-4
4-2

Ibs.
386
388
502
511
618

65-9

32-0

14-1

6-8

469

128 THE CHEMISTRY OP THE FAEM.

The figures in this table illustrate in a striking manner
the alterations in the proportion of food consumed, and
increase yielded, during the period of fattening. The
weights of food refer to meal in its natural state, and
do not represent dry substance. The irregularities in the
progression of the figures are due to the variable appetite
and condition of the animals. Animals when first con-
fined, and supplied with fattening food, generally increase
largely in weight during the first few weeks, after
which the rate of increase diminishes to a considerable
extent.

The composition of the animal increase accumulated
during fattening has been already given on page 79.
The proportion of nitrogenous matter in this increase is
very small, the albuminoid ratio of the increase in the
case of the pig being only 1 : 19, and in that of the sheep
1 : 22. For the purpose of rapid fattening we must not,
however, provide food containing as low a proportion of
albuminoids as is stored up in the increase ; the animal
body, in fact, requires a constant supply of albuminoids
for the renovation as well as for the production of tissue.
A diet tolerably rich in albuminoids is also both more
digestible, and of greater feeding value, than a diet poor
in this constituent.

Wolff recommends a more nitrogenous diet for fat-
tening sheep than for oxen or pigs. The ratio of nitro-
genous to non-nitrogenous substance which he recom-
mends for fattening sheep is 1 : 5*5, concluding with
1 : 4'5. For pigs, 1 : 4 — 5 below 5 months, and 1 : 5.5 —
1 : 6*5, as the age and weight increases. For oxen 1 : 6'5
at the commencement of fattening, to be reduced to 1 : 5.5
when fattening in earnest has set in. In all these diets,

PKODUCTION OF WOOL. 129

however, the amides have been reckoned as albuminoids ;
the ratios are thus too narrow, the error falling chiefly on
the diets of the sheep and oxen. Practical results show
that very good rates of increase may be obtained with
smaller proportions of albuminoids than those recom-
mended by Wolff, if cereal grains form a considerable
part of the diet. Thus, a three years' trial at Woburn
proves that a daily ration of 20 Ibs. swedes, J Ib. hay, and
J Ib. wheat for sheep (nitrogenous substance to non-
nitrogenous 1 : 6 — 7, albuminoid ratio about 1 : 11)
yields excellent results, generally equal to those obtained
when cake is substituted for wheat. The economy of
any diet cannot, however, be decided without taking into
account the value of the manure produced. From this
point of view, fattening with cake or leguminous corn
maybe more to the farmer's advantage than the employ-
ment of cereal grains.

Fat, as we have already seen, is the most potent of
the constituents of food ; oil-cakes rich in oil have thus
a special value for the production of concentrated diets,
and are peculiarly adapted for winter feeding.

Young animals require a more nitrogenous diet
during fattening than animals of maturer age, as growth,
as well as fat, must be provided for.

Production of Wool. — Wool, besides the moisture and
dirt which it naturally contains, is made up of three in-
gredients, suint, fat, and pure wool-hair. The suint is
an excretion of the perspiration glands of the skin ;
it chiefly consists of a compound of potassium with an
organic acid containing nitrogen, of which little is known.
Suint is soluble in water, and is in great part removed

10

130 THE CHEMISTRY OF THE FARM.

when sheep are washed before shearing. In the case of
Merino sheep the suint may amount to more than one-
half the weight of the unwashed fleece ; but in the case of
ordinary sheep, freely exposed to weather, the quantity
may be 15 per cent, or less. In a washed fleece the fat
may vary from more than 30 per cent, to 8 per cent., or
less. Short fine wool contains the largest proportion of
fat. Pure wool-hair contains about 16 per cent, of
nitrogen. The quantity of nitrogen and ash constituents,
both in unwashed and in washed wool, has been already
given on page 78.

The production of wool-hair and of wool-fat is
practically no greater when sheep receive a liberal fatten-
ing diet, than when the diet only suffices to maintain the
ordinary condition of the animal ; indeed, under poor
treatment, the carcase may lose weight to some extent
without the production of wool being seriously altered.
With starvation, however, the yield of wool is con-
siderably diminished. If sheep are kept on a poor diet
for the mere production of wool, the amount of
albuminoids supplied must not fall too low, wool-hair
being formed entirely from this part of the food.

Production of Milk.— The quantity of milk produced
is largely determined by the individual character of the
animal, and the length of time which has elapsed since
birth ; the quality of the milk is also affected by the
same conditions. Subject to these natural limitations,
both quantity and quality are greatly influenced by
the character of the food supplied.

A liberal diet is essential for a full supply of milk.
Tbe milk yielded by each cow should be recorded, and

PEODUCTION OP MILK. 131

the supply of concentrated food (cake, bean meal, bran,
&c.) should rise and fall with the yield of milk, the
object being to obtain as large a produce as can be
reached without fattening the animal. The best feeding-
will not turn a badly milking cow into a good one, but it
is possible by sustaining the cow with proper food at the
period of her greatest milk production to prolong that
profitable period very considerably. Green fodder is
favourable to a large produce, so also are brewers' grains.

As milk is a highly nitrogenous product, the albuminoid
ratio in cow's milk being 1 : 3*6, it is obvious that cows
in full milk will require a nitrogenous diet. Such a diet
is naturally provided when cows feed on young grass and
clover; when hay, straw, and roots form the bulk of the
food, it is imperative that cake or leguminous corn be
also employed if abundance of milk is desired. Wheat
bran, and brewers' grains, are generally recognized as
good milk foods, and are shown by the table on page 111
to have a high albuminoid ratio. Wolff gives 1 : 5'4 as
the ratio of nitrogenous to non-nitrogenous substance
suitable for cows in full milk. Practice shows that an
albuminoid ratio of 1 : 6 — 8 is sufficient, the higher ratio
of albuminoids being reserved for cows yielding 40 —
50 Ibs. of milk per day.

Milk is far more nitrogenous than the increase of
carcase obtained when an animal is fattened. If a cow
yields 21 gallons per week, the nitrogen in the milk will
be about equal to that contained in 100 Ibs. increase of
fattening oxen. The saleable nitrogenous matter yielded
by one cow will thus equal that produced in the same
time by 6 — 10 oxen.

The quality of milk is considerably influenced by the

132 THE CHEMISTRY OF THE FARM.

richness of the diet. A diet of watery grass" will
probably yield a moderate quantity of poor milk; the
addition of oil-cake will increase both, the yield of milk
and also its richness. The alteration in the composition of
milk by poor or liberal feeding is chiefly an alteration in
the percentage of solid matter; the relative proportions
of casein and sugar are scarcely affected by the character
of the diet, the butter-fat is more variable.

The quality of the butter is more or less influenced
by the character of the food, some foods producing a
hard, and others a soft butter. Rape-cake, oats, and
wheat-bran are reckoned in Denmark as first-class butter-
foods; cotton-cake, palm-nut cake, and barley as second-
class foods ; while linseed-cake, peas, and rye are placed
in the third class. The first-class foods produce a soft
butter, the third-class foods a hard butter. By the
employment of first and second-class foods with straw,
chaff, hay, and roots, an abundance of excellent butter
may be produced throughout the winter. Turnips
strongly flavour both milk and butter; carrots and
mangels are a better food for milk-cows.

CHAPTEE IX.

EELATION OP POOD TO MANURE.

Quantity of the Manure — How calculated — Character of manure from
horses, cattle, sheep, and pigs. The Litter — Its absorbent power and
composition. Composition of Manure — Proportion of the ash con-
stituents and nitrogen of the food which appears in the liquid and
solid excrements — Composition of the excrements of sheep, oxen
and cows. Manure value of Foods — The quantity of nitrogen and
ash constituents contained in foo:ls — Their value as compared with
the same materials in artificial manures — Economic use of manure.

Quantity of the Manure.— This is very variable,
depending largely on the amount of indigestible matter
in the diet. Thus the quantity of manure credited to
the fattening ox and sheep in the table on p. 124, would
be greatly increased if a portion of the roots in their diet
was replaced by straw- chaff. The manure credited to
the pig would be much less if, instead of barley meal, it
had received potatos and skim milk.

The quantity of dry matter in the solid excrement of
an animal may be calculated from the digestion co-efficient
of the diet. The quantity of dry matter in the urine is,
according to Wolff, nearly 6 por cent, of the dry food
Consumed.

The mixed excrements of pigs and cattle are far
more watery than those of sheep and horses, a larger
proportion of litter has therefore to be used for the first-
named animals. Pigs and cattle thus yield a bulky,

THE CHEMISTRY OF THE FARM.

watery manure, sheep and horses a drier and more con-
centrated product. Manure freshly made, with a minimum
of litter, will contain 73 — 80 per cent, of water.

The Litter.— The worth of a litter depends partly on
its power of retaining water, and partly upon the manurial
constituents which it itself supplies.

WATEE RETAINED BY 1 PART OF LITTER.

Dead leaves .
Straw .
Peat moss

2-0
. 2-2—3-0
3-8

Sawdust
Spent tan
Peat .

. 4-J— 4-4
. 4-0—5-0
\ 5-0—8-0

MANURIAL CONSTITUENTS IN 100 PARTS OF LITTER.

Nitrogen.

Phosphoric
Acid.

Potash.

Dead leaves

0-8

0-3

0-3

Straw .

0-4—0-6

0-2—0-3

0-6—1-6

Peat moss

0-8

trace

trace

Sawdust

0-2—0-7

0-3

0-7

Spent tan

05— 1-0

—

—

Peat .

1-0—2-0

* --

—

Peat is thus, of all forms of litter, both the most
efficient absorbent, and also the one supplying the largest
amount of valuable matter.

Composition of Manure.— In the case of an adult
animal, neither gaining nor losing weight — a working
horse, for instance — the quantity of nitrogen and ash
constituents voided in the manure will be nearly the same
as that contained in the food consumed, the albuminoids
and ash constituents of the food used for the renovation

COMPOSITION OF MANUKE. 135

of tissue being in this case equivalent to the quantities
yielded by the degradation of tissue. In cases where
the animal is increasing in size, is producing young, or
furnishing wool or milk, the amount of nitrogen and ash
constituents in the manure will be leus than that in the
food in direct proportion to the quantity of these sub-
stances which has been converted into animal produce.
The manure from animals of the latter description will
thus be poorer than that obtained from the former class,
supposing the same food to be given to each.

The proportion of the nitrogen in the food which will
appear in the solid excrement is determined by the diges-
tion co-efficient of the nitrogenous constituents. Thus 78
has been already given as the digestion co-efficient of the
nitrogenous matter of barley meal when consumed by a
pig; it follows that in this case for 100 of nitrogen con-
sumed 22 will be voided in the solid excrement, and 78
pass into the blood. Ifc has been already stated that
500 Ibs. of barley meal, containing about 531bs. of
nitrogenous substance, will in the case of a fattening pig
produce 100 Ibs. of animal increase, containing 7*8 Ibs. of
albuminoids. It follows from these data, that for 100 Ibs.
of nitrogen consumed, 14*7 are stored up as carcase, 22
appear in the solid excrement, and 63*3 as urea, &c., in
the urine. In the same way, by deducting the ash con-
stituents stored up from those present in the food, we can
arrive at the quantity of ash constituents voided in the
manure. The following table shows the results obtained
by this mode of calcuktion in the case of the fattening
ox, sheep, and pig receiving the diets mentioned on page
124. The relation of food to manure in the case of
milking cows is calculated from recent Rothamsted

136

THE CHEMISTRY OP THE FAEM.

experiments, in which cows receiving a liberal diet
yielded an average of 271bs. of milk daily. The horse
at rest is assumed to receive as a maintenance diet 19 Ibs.
of meadow hay; the horse at work, 15 Ibs. of hay and
10 Ibs. of oats daily.

NITROGEN IN ANIMAL PRODUCE, AND VOIDED,
FOR 1.0 CONSUMED AS FOOD.

Obtained as
carcase or
milk.

Voided as
solid excre-
ment.*

Voided as
liquid
excrement.

In total
excr ement

Horse, at rest
,, at work
Fattening oxen
Fattening sheep
Fattening pigs
Milking cows

None.
None.
3-9
4-3
14-7
24-5

43-0
29-4
22-6
16-7
22-0
18-1

57-0
70-6
73-5
79-0
63-3
57-4

100
100
96-1
95-7
85-3
75-5

ASH CONSTITUENTS IN ANIMAL PRODUCE, AND VOIDED
FOR 100 CONSUMED AS FOOD.

Obtained as
live weight
or milk.

Voided in ex-
crements and
perspiration.

Horse

None.

100

2-3

97-7

Fattening sheep
Fattening pigs ......
Milking cows ......

38

4-0
10-3

96-2
9/0
89-7

The proportion of the ash constituents and nitrogen
of the food which is stored up in the body of an animal

* The quantities of nitrogen given in this column are a little below
the truth, as, besides the undigested albuminoids, some nitrogenous
biliary matter is present in the solid excrment. With oxen and sheep
the amount of biliary matter in the excrement is very small ; with pigs
it is more considerable. In the case of the pig the nitrogen in the
solid excrement should probably stand as 26'0, and that in the liquid
as 59-3.

COMPOSITION OF MANURE. 137

is generally very small. In the case of the fattening
animals, 96 per cent., or more, of the ash constituents of
the food find their way into the manure. With fatten-
ing oxen and sheep, and with horses, more than 95 per
cent, of the nitrogen of the food are voided in the
manure. The pig is seen to retain a much larger pro-
portion of the nitrogen of its food, about 85 per cent,
appearing in the manure. The milking cow gives the
best return in saleable produce for the nitrogen which
it receives, only about 75 per cent, appearing in the
manure. With diets containing a smaller amount of
albuminoids the proportion of nitrogen appearing as
manure will of course be diminished.

The amount of nitrogen voided in the urine is seen to
be always greater than the quantity contained in the
solid excrement, and is generally three or four times as
much. This relation will vary according to the character
of the diet. If the food is nitrogenous, and easily
digested, the nitrogen in the urine will greatly pre-
ponderate ; if, on the other hand, the food is one imper-
fectly digested, the nitrogen in the solid excrement may
form the larger quantity. When poor hay is given to
horses, the nitrogen in the solid excrement will exceed
that contained in the urine. On the other hand, corn, cake,
and roots yield a large excess of nitrogen in the urine.

The ash constituents are very differently distributed
in the solid excrement and urine ; in the former is found
nearly all the phosphoric acid, and the greater part of the
lime and magnesia, while the latter contains the greater
part of the potash. With sheep and horses, and probably
more or less with other animals, a part of the potash is
excreted in the perspiration.

138

THE CHEMISTRY OP THE FARM.

Some idea of the general composition of the solid
excrement, and of the urine, is given by the following
table. The sheep were fed on meadow hay ; the oxen on
clover hay and oat straw, with about 8 Ibs. of beans per
day; the cows received in one case 154 Ibs. of mangels,
and in the other case 26 Ibs. of lucerne hay and 66 Ibs.
of water per day.

PERCENTAGE" COMPOSITION OF SOLID AND LIQUID

EXCREMENT.
1. SHEEP FED ON II AY

Water . .
Organic matter .
Ash . . . .

Solid excrement.

Urine.

Fresh.

Dry.

Fresh.

Dry.

66-2
30-3
35

896
10-4

85-7
8-7
5-6

6i -o

39-0

Nitrogen . .

0-7

20

1-4

9-6

2. OXEN WITH NITROGENOUS DIET.

"Water

Solid excrement.

Uriue.

Fresh.

Dry.

Fresh.

Dry.

' 3V0
37'0

86-3
12-3
1-4

89-7
10-3

941
3-7
2-2

Organic matter ....
Ash

Nitrogen

0-3

1-9

1-2

20-6

3. COWS FED ON MANGELS, AND ON LUCERNE HAY.

Fresh manure per day

Mangels.

Lucerne Hay.

Solid
excrement.

Urine.

Solid
excrement.

Urine.

Ibs.
14

Ibs.
42

Ibs.
88

Ibs.
48

Water ....

Nitrogen
Phosphoric acid .
Potash .

Per cent.
83-00
•33
•24
•14

Per cent.
95-940
•124

•on

•597

Percent.
79-70
•34
•16
•23

Per cent.
88-2.0
1-540
•006
1-690

MANURE VALUE OF FOODS.

139

The immense influence of the character of the diet,
both on the quantity and quality of the manure, is well
shown by the two experiments with cows ; the difference
appears chiefly in the urine.

The richness of the urine, both in ash constituents
and nitrogen, is in all cases very evident. In the case of
the more highly-fed oxen, the dry matter of the urine is
seen to contain over 20 per cent, of nitrogen.

Manure Value of Poods.— The relative value of the
manure produced by different foods is determined by the
relative richness of the foods in nitrogen and ash con-
stituents, but chiefly by the amount of nitrogen, this
being the most costly ingredient of purchased manure.
The average amount of nitrogen, and of the two most
important ash constituents contained in ordinary cattle
foods, is shown in the following table : —

MANURIAL CONSTITUENTS IN 1000 PARTS OF ORDINARY
FOODS.

Dry

matter.

Nitrogen.

Potash.

Phos-
phoric
Acid.

Cotton cake (decorticated)
Rape cake ....

918

887

70-4
50-5

15-8
13-0

30-5
20-0

Linseed cake .

883

43-2

ls-5

16-2

Cotton cake (undecorticated) .
Linseed

878
882

33-3
3_'8

20-0
10-0

22-7
13-5

Palm-kernel meal (English) .

980

io'O

5-5

12-2

855

40-8

11-9

121

Peas

857

35-8

101

8-4

Malt dust

905

37-9

20-8

18-2

Bran

86)

23-2

15-3

26-9

Oats

870

206

4-8

6-8

Rice meal

900

lirl

6-1

23-8

Wheat .

877

18-7

5-2

7-9

140

THE CHEMISTRY OP THE FAEM.

MANURIAL CONSTITUENTS IN 1000 PARTS OF ORDINARY
FOODS.— continued.

1

Dry
matter.

Nitrogen.

Potash.

Phos-
phoric
Acid.

Rye .....

857

17-6

5-8

8-5

Barley

860

17'0

4-7

7-8

Maize

890

16-6

3-7

5-7

i Brewers' grains

234

7-8

0-4

3-9

Clover hay

840

19-7

18-6

5-6

Meadow hay

857

15'5

16-0

4-3

Bean straw

840

13-0

19-4

2-9

Oat straw

857

6-4

16-3

2-8

Barley straw

857

5-6

10-7

1-9

Wheat straw

857

4-8

6-3

2-2

Potatos .

T50

3-4

5'8

1-6

Svvedes . .

107

2'J

2-0

0-6

Carrots

140

2-1

3-0

1.1

120

TS

4-6

0-7

' Turnips

80

1-6

2-9

0-8

The manure value of different food thus varies
extremely. One ton of decorticated cotton cake contains
about four times as much nitrogen as a ton of wheat,
barley or maize, and thirty-nine times as much as a ton
of mangel wurzel.

The oil-cakes yield the richest manure, as they contain
the largest amount of nitrogen and phosphoric acid, with
a considerable amount of potash. Next to these come
the leguminous seeds, malt-dust, and bran. Clover hay
yields a rather richer manure than the cereal grains,
while meadow hay stands below them. The cereal grains
and the roots contain about the same proportion of
nitrogen in their dry substance; the roots, however,
supply much more potash. Potatos stand below roots in

VALUE OP ANIMAL MANURE. 141

manurial value, when compared on the basis of their dry
substance. Wheat-straw takes the lowest place when
foods are compared on the basis of their dry substance.
Bean and pea straw are far more valuable than the
straw of the cereals.

To obtain the amount of nitrogen, potash, and phos-
phoric acid voided as manure, we have simply to subtract
from the amounts of these constituents contained in the
food the quantity retained by the animal. The manure
resulting from nitrogenous foods, as decorticated cotton-
cake, is frequently the cheapest form of nitrogen which
a farmer can obtain. This is especially the case when
the food is skilfully used, and gives a good return in
animal increase, as well as furnishing a supply of
manure.

The ash constituents present in animal manure have
probably the full money value of the same constituents in
artificial manures, but the nitrogen has a lower value
than the nitrogen of ammonium salts or nitrate of sodium.
The nitrogenous matter of the urine (urea) is rapidly
converted into carbonate of ammonium by the action of
certain bacteria present both in the atmosphere and in
the soil; the carbonate of ammonium may afterwards
be converted into nitrates in the soil. If these changes
occurred without loss, the nitrogen of the urine would have
an equal money value with the nitrogen of ammonium
salts, or nitrate of sodium ; owing, however, to the vola-
tility of carbonate of ammonium, considerable losses are
apt to occur during the decomposition of urine.

The nitrogen of the solid excrements is not in a form
suitable for plant food, and will be only slowly converted
into nitrates in the soil. Taking into consideration both

142 THE CHEMISTRY OP THE FARM.

the losses during preparation, and the slowness of action
of farmyard manure, Lawes and Gilbert estimate that the
manure actually obtained from food has not more than
half the money value of the manurial constituents voided
by the animal, if these are reckoned at the prices given
for nitrogen, phosphates and potash in artificial manures.

Animal manure is more immediately available for the
use of plants when applied directly to the land than
when previously fermented with a great bulk of litter.
During fermentation with litter the ammonia unites
with certain of the carbonaceous matters present, forming
compounds which are little soluble, and which decompose
but slowly in the soil.

The feeding of animals on the land is a mode of
applying manure which has many advantages ; but the
distribution of the manure is in this case irregular, and if
carried out in autumn or winter the manure is subject to
loss by drainage. The most effective plan of application
is doubtless as liquid manure to growing crops. In
winter time, however, the use of litter, and the preparation
of farmyard manure (best under cover), becomes a
necessity, and is on the whole the best course to adopt.

The treatment of farmyard manure, and its general
composition, have been already described on pp. 31-33.

CHAPTER X.

THE DAIEY.

Milk. — Its constituents — Conditions affecting its richness. Curdling. —
The action of bacteria. Cream. — The fat globules — Modes of
raising cream — Composition of cream — Kipening of cream. Skim-
milk. — Its composition. Butter. — The operation of churning —
Composition of butter. Butter-milk. — Its composition. Cheese. —
Rennet — Operation of cheese-making — Composition of cheese.
Whey. — Its composition. Annatto. — Its nature and use. Necessity
for cleanliness.

Milk.— The general composition of colostrum, and of
ordinary cow's milk, has been already given on p. 117.

Cow's milk has generally a specific gravity of 1*032,
the extremes being about 1*028 and T035. As the
removal of cream raises the specific gravity, which can
be brought back to the normal point by the addition of
water, no safe conclusion as to the quality of milk can be
based on this indication.

The albuminoids of milk are chiefly composed of two
constituents of similar composition, casein and albumin.
Casein is coagulated by the addition of acids, or by
rennet, but not by boiling. Albumin is not coagulated
by rennet, or by most acids, but is coagulated by heat.
In colostrum albumin largely preponderates, so that the
milk coagulates on boiling ; in ordinary cow's milk the
albumin forms about one-eighth of the total albuminoids.

The fat of milk chiefly consists of the glycerides of

144 THE CHEMISTRY OP THE FARM.

palmitic and oleic acid. The glycerides of stearic,
myristic, lauric, capric, capryllic, caproic, and butyric
acid are also present in small quantity. The last four of
these acids are, when in the free state, more or less
soluble in water. The glycerides of oleic acid, and of
the soluble fatty acids, are fluid fats at ordinary tem-
peratures ; the remaining fats are solid. The proportion
of fluid and solid fats varies somewhat with the diet and
condition of the animal ; in summer-time the proportion
of fluid fats is greater than in winter.

The sugar contained in milk is known by chemists as
lactose or lacton.

The composition of cow's milk is affected by various
circumstances; under extreme conditions it may con-
tain from 10 to over 16 percent, of dry matter. The
milk is poorer when the quantity produced is large,
or the diet insufficient, and richer when these con-
ditions are reversed. A cow is generally in full milk
from the second to the seventh week after calving;
after this period the milk gradually diminishes in
quantity, but increases in richness. A separation of
cream takes place in the udder; the milk first drawn is
poor in fat, and the richness increases as milking pro-
ceeds, the last-drawn milk containing two or three
times as much fat as the first- drawn. The evening's
milk is usually somewhat richer than that of the morning,
the assimilation of food taking place to a larger extent
between the morning and evening than between the
evening and morning milkings. The milk of old cows
is said to be poorer than the milk of young cows. The
richness of milk depends also much on the " race " of
the cow, the fat being the constituent most affected.

CURDLING. 145

The Jersey breed gives the richest milk, the fat fre-
quently amounting to 5 — 6 per cent.

The influence of diet on the production of milk and
butter has been already considered (p. 130).

Curdling.— The ordinary souring of milk is produced
by various species of bacteria, which, during their growth
convert the sugar of milk into lactic acid; this acidi-
fication of the milk induces the coagulation of the
casein. The higher is the temperature, the smaller
is the proportion of acid which will curdle milk.
Milk is also curdled by other species of bacteria, which
produce no, or very little, acidity, but apparently act
by the formation of a rennet-like ferment. Other fer-
ments, altering the condition of the albuminoids in milk,
are produced by other species of bacteria. The presence
of these ferment-forming bacteria sometimes occasions
much difficulty in dairy work, and is the cause of many
of the so-called " diseases " of milk. The development
of these mischievous bacteria may be checked by cooling
the milk while the cream is rising. The speedy work
done by the centrifugal machine is also most valuable
for this purpose. All bacteria are destroyed at a boiling
heat. Milk that is free from micro-organisms is un-
changed by keeping.

Cream.— The fat of milk occurs in the form of globules;
the largest are about '0005 to '0006 inch in diameter,
the smallest may be one-tenth this diameter, or even less.
The average size of the globules is different with different
breeds of cattle ; thus they are larger in the milk of the
Jersey than in the milk of the Ayrshire or Holstein breed.

11

146 THE CHEMISTRY OF THE FAITJ.

The large globules diminish in number as the time from
calving increases. As the fat globules have a lower
specific gravity than the serum in which they float, they
tend to rise to the surface, where they form a layer of
cream. The largest globules are the first to rise; the
smallest never rise at all. Milk containing an abundance
of large globules is best for butter-making, as the cream
then quickly and perfectly rises ; but milk with small
globules is probably best for cheese-making, as a more
even distribution of fat throughout the curd is then
obtained.

Milk, when it leaves the cow, will have a temperature
of about 90° Fahr. ; when set for cream it should be
cooled as quickly as possible, as changes in composition
would rapidly occur at a high temperature. Milk is
usually set for cream in shallow vessels, the depth of
milk being perhaps three inches ; in these vessels the milk
stands for thirty-six to forty-eight hours till the cream
has separated. Under these conditions a large surface
is exposed, the milk receives a large number of bacteria
and moulds from the air, and a maximum amount of change
takes place ; the result is a decomposition of a part of
the albuminoids and fats, the production of lactic acid,
and the partial curdling of the milk. The cream obtained
in this way is contaminated with curd, and contains
various strongly-flavoured products of decomposition,
which deteriorate the quality of the butter.

On Swartz's plan the milk is placed in metal pails,
16 inches deep, and surrounded by ice. The cream rises
quickly, and can all be obtained in twelve to twenty-four
hours from the time of setting. Cream thus prepared is
perfectly sweet, and free from curd, the low temperature

GEE AM. 117

at which the milk has been kept having reduced chemical
change to a minimum. It occasionally happens that milk
will not yield its cream at low temperatures; this is
sometimes the case with the milk of cows several months
after calving, and especially when receiving a winter diet.

A third plan of separating cream is by subjecting the
milk to extremely rapid horizontal revolution in a centri-
fugal machine; under these circumstances the fat globules
rise into the centre of the revolving mass. In Laval's
machine the new milk, at a temperature of 84°, enters
in a continuous stream, and is immediately separated into
cream and skim-milk, the former leaving the apparatus
by a pipe at the top, the latter by another pipe from the
side. Both the cream and skim milk thus obtained are,
of course, perfectly sweet. The separation of cream in
the centrifugal machine is far more complete than in
either of the other processes. About 80 per cent,
of the milk fat is removed by the ordinary process of
shallow setting, and about 95 per cent, by a good machine.
A much larger quantity of butter can thus be obtained
with a machine than by any other mode of working.

Cream varies considerably in composition according
to the manner in which it has been produced. The
volume of the cream obtained is always greater at a lower
temperature; this fact should be borne in mind when
comparing results given by the creamometer. Cream
raised in ice will contain about 20 per cent, of fat. Cream
obtained by ordinary shallow setting may contain 25 — 40
per cent, of fat. Cream separated by the centrifugal
machine will vary extremely according to the mode of
working; it may be quite poor, or it may contain 50 per
cent., or more, of fat. Casein, and the other constituents

148 THE CHEMISTRY OP THE FARM.

of milk, are always present in small quantity. In sweet
cream the casein may be about one-tenth of the fat ; in
the cream from milk which has soured during setting the
casein forms a much larger proportion.

The perfectly sweet cream obtained by using ice, or the
centrifugal separator, is frequently slightly soured or
"ripened" before churning. For this purpose a little
buttermilk is stirred in, and the cream warmed to about
70°. As soon as the cream thickens it must be churned,
or else immediately cooled, to prevent the change proceed-
ing further. It is claimed that rather more butter can
be obtained from ripened cream than from sweet cream ;
the flavour of the butter also is altered.

Skim Milk.— Milk thoroughly skimmed in the ordinary
way will still contain about 0.8 per cent, of fat, and more
thao this quantity is frequently present. When ice has
been used, the percentage of fat left in the milk will be
05 to 0*7; and when the centrifugal machine has been
employed, 0*2 to 0*5. Skim milk obtained in the ordinary
way will contain about as follows : water, 90'0 ; albu-
minoids, 3'6; fat, 0*8; sugar, 4*9; ash, 0*7. Its specific
gravity is generally 1*034 to 1'037. Skim milk is a very
nitrogenous food, the albuminoid ratio being as high as
1 : 1-8.

Butter.— The object of butter-making is to bring
about the union of the fat globules which in milk and
cream have existed separate from each other. The skilled
butter-maker is not, however, satisfied with producing
a solid mass of butter-fat ; for butter to be of good quality
it must possess a certain texture and grain, and be neither

CHURNING. 149

hard nor greasy ; this desired result can only bo attained
by careful churning at a favourable temperature. If the
temperature of the cream is too low the butter will be
long in coming, and will be hard in texture. If the
temperature is too high the butter will come very speedily,
but the product will be greasy, destitute of grain, and
deficient in quantity. No temperature can be fixed as
the best at which churning should always take place
The proportion of solid and fluid fats in the milk varies
somewhat with the diet of the cows, and this necessitates
a change in the temperature. A rather higher tempera-
ture will be required in winter than in summer. The
temperature must also be higher for sour cream than for
ssveet cream. G-enerally speaking, perfectly sweet cream
should be placed in the churn at 52° to 55° Fahr., and
sour cream at 59° to 63°. When sour milk is churned
for butter the temperature must be about 65°. The exact
temperature most suitable for churning may be ascertained
by recording every day the temperature employed, with
the length of time occupied in churning, and the amount
and character of the product ; when this is done the
temperature for each day can be regulated from the
experience of the last working. The temperature will
rise several degrees during churning.

Churning must always be stopped as soon as the butter
appears in fine grains ; any over- churning spoils the
texture of the butter. The butter is then separated from
the buttermilk, washed with cold water, and after standing
to solidify is carefully worked and pressed to expel all
watery matter ; over-working in this stage will also spoil
the grain, and make the butter greasy. Butter made
from perfectly sweet cream keeps far better than

150 THE CHEMISTRY OP THE FARM.

butter made from sour cream, as the latter always
contains curd, a substance very prone to change. Salt
is generally added to improve the keeping quality of
butter. Good churning should result in 96 per cent, of
the cream fat being obtained as butter fat.

First-class butter will contain a minimum of about
10 per cent, of water, and 0*5 per cent, of casein. In
ordinary fresh butter the water is usually 11 — 15 per
cent., the fat 83 — 87, the casein 0'6 — 1*0, the milk sugar
0-2— -0-7, and the ash O'l— 3'0 per cent. The amount of
ash depends chiefly on the quantity of salt added. Of
the fatty acids in butter about 6 per cent, are soluble in
water when separated from the glycerol with which they
are combined ; this fact serves to distinguish butter from
other animal fats in which soluble fatty acids are absent.
When butter becomes rancid the glycerides of the fatty
acids are partly decomposed, and the fatty acids liberated;
the odour and flavour of rancid butter are largely due to
free butyric acid.

Buttermilk.— The liquid remaining in the churn after
the separation of the butter from the cream varies a good
deal in composition; the average will be about as follows : —
Water, 90'1 ; albuminoids, 4'0 ; fat, 1*1 ; sugar, 4'1 ; ash,
0*7 per cent. The albuminoid ratio would thus be
1:1-6.

Cheese.— This substance is prepared by the action of
rennet on milk. Rennet is made by extracting the
fourth stomach of the calf with water containing 5 per
cent., or more, of common salt. Its power of coagulating
milk is due to the presence of a ferment, which doubtless

CHEESE MAKING. 151

plays a similar part in tie ordinary process of digestion
in the calfs stomach. Kennet solidifies the milk by
separating the casein from solution ; the fat globules are
separated at the same time, being entangled in the curd
formed. The action of rennet is very slow in the case
of cold milk; it acts most speedily at a temperature of
98° Fahr. ; above this point the action rapidly declines,
and ceases at about 130° Fahr. Milk becomes slightly
sour when curdled by rennet, but the production of acid
(lactic acid) is not essential to the curdling.

The composition of cheese depends greatly on that of
the milk from which it is made ; rich cheese is made
from new milk, cream being sometimes added to the
milk for the production of the richest sorts ; poorer kinds
of cheese are made from milk wholly or partially
skimmed.

The temperature at which the milk is curdled is of
great importance. If the temperature is low the curd is
very tender, and the whey difficult to separate ; if, on the
other hand, the heat is too great, the curd shrinks too
much, and becomes hard and dry. Temperatures from
75° — 90° are employed for different kinds of cheese, but
80° — 86° is the temperature most commonly chosen.

When the curd is sufficiently firm it is carefully cut in
all directions, and the whey allowed to drain off. The
curd is often scalded with hot whey after cutting, with
the view of making it shrink and harden : the temperature
used at this point must not exceed 100° Fahr. The
drained and broken curd is next put into a press, to
remove more effectually the last portions of whey. It is
then pulverised in a mill, salted, again passed through
the mill, and is then ready for filling into the frames.

152 TH£ CHEMISTRY OP THE FARM.

Curd when put into the frames should contain, according
to Voelcker, about 54 per cent, of water when thin cheese
is to be made, and not more than 45 per cent, if thick
cheese is manufactured. The curd from skim milk will
contain much more water than a curd rich in butter.
The frames filled with curd are subjected to a gradually
increasing pressure for several days. The cheese is
finally removed from the frame and placed in the cheese-
room to ripen.

In making soft cheese the curd is not cut or pressed,
but is simply allowed to drain in a cloth or frame.

Cheese ripens quickest at a moderate temperature ;
65° — 70° is frequently employed at first, and afterwards
a lower temperature. During the operation a loss of
water takes place, the loss being greatest in the case of
poor cheese. If decay, or growth of mould, occurs, a
further considerable loss of weight takes place, the casein
and fat of the cheese being decomposed by the organic
life thus introduced, while carbonic acid, ammonia, and a
variety of other products are formed. It was once
believed that fat was produced during the ripening of
cheese ; this, however, is not the case.

The different qualities of cheese are chiefly determined
by the richness of the milk; its sweetness or acidity; the
proportion of rennet used ; the temperature of curdling ;
the scalding and manipulation of the curd ; the pressure
to which it is subject; the temperature of the cheese-
room, and the age of the cheese. Curdling at a low or
medium temperature, the omission of scalding, and a
light pressure in the cheese frame, are employed in the
case of cheeses intended to ripen early and develop
mould.

WHEY. 153

A very ricli cheese, as old Stilton, may contain about
20 per cent, of water, 44 per cent, of fat, and about 29
per cent, of casein. In a good Cheddar or Cheshire
cheese we should find about 33 per cent, of water, 33 per
cent, of fat, 28 per cent, of casein, and about 3 to 4 per
cent, of ash constituents, nearly half of which would be
common salt. In skim milk cheeses the percentage of
water is greater, and that of fat less. Thus a poor single
Gloucester may contain 38 per cent, of water, 22 per cent.
of fat, and 31 per cent, of casein. In skim milk cheese
made in Denmark, from milk from which the cream has
been very completely removed by the ice system, only 4
or 5 per cent, of fat are present.

Whey.— The whey which drains from the curd in
cheese-making is a perfectly transparent liquid, containing
the sugar and albumin originally present in the milk ; it
should not contain more than a trace of butter. If, how-
ever, the curd has been roughly treated, the milk has
been rich, and the temperature high, larger quantities of
butter will be present, and the cheese suffer in conse-
quence. When whey is rich in butter it is generally
allowed to stand till the butter has risen j the butter may
then be added to the next churning. The average com-
position of whey is about as follows: — Water, 93*4;
albuminoids, 0*9; fat, 0*3; sugar and lactic acid, 4*8;
ash, 0*6. The albuminoid ratio is 1 : 5*6.

Annatto.— This is prepared from the pulpy coating of
the seeds of Bixa Orellana. The orange colouring
matter is soluble in alkalis, and in oil. Solid annatto
contains much alkali carbonate, it is therefore soluble in

154 THE CHEMISTRY OF THE FAKM.

water. When used for colouring butter, a small quantity
of annatto solution is added to the cream before churning.
When cheese is to be coloured, the annatto solution is
added to the milk before the rennet.

Cleanliness.— In all the operations of the dairy the
greatest cleanliness must be observed ; all vessels should
be washed with hot water as soon as done with, to destroy
any adhering ferment. Without such precautions no
good butter or cheese can be made.

Information as to the loss to the farm by the sale of
milk and dairy products has been already given on p. 78.

INDEX.

ACIDS in plants, 3, 7, 9.
Adult animal, 118.

— — maintenance diets, 120.
Albumin of colostrum and milk, 143.

— heat-producing value, 83, 108.
Albuminoids in animals, 76-79.

— digestion of, 84.

— formation in plants, 7.

— in foods, 81, 88-91.

— in milk, 117, 143.

— loss of, in ensilage, 95.

— oxidation of, 81, 85.

— their part in nutrition, 81.
Albuminoid ratio in buttermilk, 150.

— — in diets, 118, 121,

128, 131.

— — in foods, 110.

— — in milk, 117.

— — in skim-milk, 148.

— — in whey, 153.
Alumina in soil, 19, 27.
Amides, 2, 7, 10, 20.

— in foods, 89, 91, 93, 95.

— their part in nutrition, 82. £8.
A mmonia, absorbed by plants,5. 9, 17, 72.

— absorbed by soil, 17, 26-28,

64, 72.

— in atmosphere, 17.

— in rain, 17.

— in silage, 96.

— loss of, from manure, 32,141.

— nitrification of, 23, 36, 44.
Ammonium sulphate, 35, 36,40, 43,45.
Animal constituents. 75.

— force, source of, 80.

— heat, source of, 80.

— manure, 31, 133, 142.

— nutrition, 80.

— requirements, 116.
Annatto, Io3.

Annual plants, 14.

Artificial manuring, 43, 56.

Ash in animal products, 76-79, 117.

— in crops, 48.

— distribution in excrements, 1 £7

138.

— in foods, 88, 92, 93, 139.

— of food stored up and voided, 136.

— in plants, 2.
Asparagine, 13, 89.

Ass's milk, 117.
Atmosphere, 16.
Autumn manuring, 44.

BACTERIA, action on milk, 1 15

— oxidation by, 2-j.
Bare fallow, 8, 63.
Barley crop, 41, 48, 50, 69.

— grain, composition, 88, 140.

— — digestibility, 97, 102.

— — feeding value, 107, 109,

111, 124, 132.

— — malting, 51, 60.

— — manure value, 140.

— straw, composition, 48, 88.

— — digestibility, 97.

— — feeding value, 107, 109,

111.

— — manure value, 140.
Bean crop, 48, 52, 69.

— grain, composition, 48, 88, 139.

— — digestibility, 97, 100, 107.

— — feeding value, 107, 109, 111.

— — manure value, 139.

— straw, composition, 48, 88, 1 10.

— — digestibility, 97, 93.

— — manure value, 140.
Beech forest, 10, 49, 55.
Beetroot, 55.

Biennial plants, 15.
Bile, 84.

Biliary matter, 136.
Blood, 85.

— manure, 37, 44.
Bone manure, 38, 40, 44.
Bones, 76, 77.

Bran, rye, digestibility, 102.

— wheat, composition, 83, 139.

— — feeding value, 107, 109,

111, 112, 131.

— — manure value, 139.
Brewers' grains, 88, 107, 109, 131.
Broomrape, 6.

Buried seed, 13.
Burning soil, 29.
Butter, 148.

— foods, 132.
Buttermilk, 150.
Butyric acid, 144.

156

INDEX.

CAKES, as manure, 38, 139.
Calcium carbonate, 19, 24. 27, 41.
Calf, composition of, 77, 78.
Capillary attraction, 20, 25.
Carbo-hydrates, part in nutrition, 82.

— production in plants, 6.
Carbon in crop residues, 23.

— farmyard manure, 23.

— — plants, 2, 4, 5, 59.

— — soils, 23.
Carbonic acid in air, 16.

— — in soil, 23.
Carcase in live weight, 79.

— in increase, 79.
Casein, 143.
Cellulose, 2, 7.

— digestion of, 84, 98, 101, 102.

— nutritive value, 83, 108.
Centrifugal machine, 147.
Cereal crops, 48, 50. 60. 61. 67.
Chalk, 41.

Cheese, 150.

— loss by sale of, 78.
Chlorides in fain, 18.
Chlorophyll cells, 4, 6.
Churning, 149.

Clay, 19, 20, 22.
Cleanliness, 154.
Climate, influence of, 59, 92.
Clover crop, 48, 52, 61, 65.

— hay, composition, 48, 88, 94,

140.

— — digestibility, 97, 100, 103.

— — feeding value, 107, 109,

111, 112.

— — manure value, 140.
Colostrum, 117, 143.

Colour of soils, 19, 21, 26.

Colourless plants, 5.

Common 8i_t, 42, 106.

Cooking food, 103.

Coprolites, 40.

Corn manure, 40.

Cotton cake, composition, 88, 139.

— — digestibility, 97.

— — feeding value, 107, 109,

111, 112, 114, 131.

— — manure value, 139.
Cotyledon, 13.

Cow, ash vielded in milk and voided,
136.

— compared with ox, 131.

— manure, 133, 135, 138.

— nitrogen in milk and voided, 136.
Cow's milk, 117, 143.

Cream, 145.
Creamometer, 147.

Creatine, 76.
Cropping, continuous, 63.
Crop residues, 61.
Crops, 48.

— adaptation of manures to, 56.

— distinctive characteristics of, 67.

— influence of climate on, 53.

— rotation of, 63.
DAIRY, 143.
Deep-rooted plants, 68.
Dextrin, 2.
Diffusion, 9.

— in soils, 25.
Digestibility of foods, 96, 107.

— circumstances affecting,

102.
Digestion, 83.

— coefficient, 96.
Dissolved bones, 40.
Dodder, 6.

Drainage waters, 24, 26, 36, 44, 64, 72.
Draining, 21, 28.

EMBRYO, 12.

Endosperm, 13.

Ensilage, 95.

Enzyme, 13.

Evaporation from plants, 8, 11.

— — soil, 21.

Ewe's milk, 117.

Excrements of animals, 85, 124, 133.
Excretion in animals, 85.

— in plants, 11.

FALLOW, results of, 8, 63.
Farmyard manure, 31, 133, 142.
Fat, digestion of, 84.

— heat-producing value of, 83, 108.

— in animal body, 77.

— in animal increase, 79.

— in foods, 88.

— of milk, 117, 143.

— production from albuminoids, 7,

81, 82.

— — from carbo-hydrates, 1,

. 82-

— — in plants, 7.

— its starch equivalent, 108.

— work-producing value of, 82.
Fattening animals, 123.
Feathers, 75, 76.
Fermentation of dung, 32, 142.

— in silo, 95.
Ferric oxide, 26.

Fertility of soil, 20, 21, 27, 30.
Fibre, digestion of, «4, 98, 101—103,
105.

INDEX.

157

Fibre in foods, 88, 93, 94.

Fish manure, 35.

Flavour of food, 115.

Flesh-formers, 81.

Fodder plants, 43, 51, 52, 88, 91-93.

— — digestibility of, 97. 100,

103.

_ _ feeding value, 107, 109.
Food constituents, functions of, 81.

values of, 83, 108.
Foods, ash constituents of, 83, 92, 139.

— comparative value, 106, 114.
-— composition of, 87, 92.

— digestibility of, 96.

— digestible matter in, 107.

— economy of, 110, 112, 114.

— influence on butter, 132.

— on milk, 130.

— manurial constituents, 139.

— variations in, 92.

Force, production of, 80, 119, 122.
Forest, action on the atmosphere, 5.

— produce, 49, 55.

— soil, 20, 30, 56.
Formaldehyde, production of, 6.
Fowls, digestion of, 102.
Fungi, 10, 23.

GASTRIC juice, 84.

Geese, digestion of, 102.

Gelatinoids, 76, 81.

Germination, 12.

Glutamine, 89.

Goats, digestion of, 97.

Goat's milk, 117.

Grains, brewers', 88, 89, 91, 97, 107,

111, 131, 140.
Grass crop, 4, 48, 51, 65.

— composition of, 4, 48, 88, 93.

— digestibility of, .97, 100, 103.

— feeding value, 107, 109, 111, 131.

— manure, 40.

— variations in composition, 93.
Gravel, 22.

Green clover, composition of, 88.

— crops in rotation, 65.

— manuring, 67.

— part of plants, 5.
Ground phosphates, 38.
Growth, force used in, 80.
Guano, 34.

Gypsum, 41, 54.

HAIR, 37, 76.
Hay crop, 4, 48, 51.

— composition of, 88, 93, 140.

— digestibility of, 97, 100, 103.

Hay, feeding value, 107, 109, 111.
— manure value, 140.
Haymaking, 95, 104.
Heat, animal, 80, 119.

— relations to plants, 5, 59.

— — to soil, '21, 24.
Heat-values of food, 109.
High-manuring, effect on crops, 94.
Hoof, 37.

Horn, 37, 76.

Horse, digestion of, 99.

— labour diet of, 119, 122.

— maintenance diet, 121.

— manure, 133, 136.
Human milk, 117.

Humus, 19, 20, 21, 23, 24, 27, 28, 67.
Hygroscopicity, 20.

INCREASE whilst fattening, 79, 123.
Iron in soils, 26, 40.

KAINITB, 42.
Keratin, 76.

LA HOUR diet, 119, 122.

Lactose, 144

Lamb, 77, 78, 123.

Leaf litter, 134.

Leaves, function of, 4.

Leguminous crops, 10, 48, 52, 66, 69,

73.

Leucine, 89.

Light, action on plants, 5, 8, 59, 80.
Lignin, 2, 82, 99.
Liming, 19, 41.
Linseed, 118.

— cake, composition, 88.

— digestibility of, 97.

— feeding value, 107, 109, 111.

— manure value, 139.
Liquid manure, 142.
Litter, 134.

Losses by drainage, 24, 36, 44, 64, 72.

— during rotation, 70.
Lucerne, 52, 59, 61, 68.

— digestibility of, 97, 100.

"MAINTENANCE diets, 81, 120.
Maize, composition of, 88, 92, 139.

— crop, 48. 51.

— digestibility, 97, 100, 102.

— feeding value, 107, 109, 111.

— manure value, 139.
Malt, 13, 90.
Malt-dust, 88, 89, 91, 139.

— — digestibility, 97.

— - — feeding value, 107, 109,

158

INDEX.

Malt-dust, manure value, 139.

Maltose, 8-1.

Mangel crop, 49, 54, 60, 61, 68.

— manure, 40.

Mangels, composition of, 88, 90, 94, 140.
— - digestibility, 99.

— feeding value, 107, 111.

— manure value, 140.
Manure, adaptation to crops, 56.

— animal, 124, 1 83.

— application of, 43.

— for cereals, 51.

— for leguminous crops, 54.

— for meadow hay, 5'.'.

— for root crops, 55.

— from foods, 124, 133, 142.
Manures, 30.

Manuring, liquid, 142.

— necesssity for, 30.

— residues of, 45, 46.

— return from, 45.

— special, 57.
Maple sap, 15.
Mare's milk, 117.
Marl, 41.
Meadow, 51, 65.
Meat, guano, 37.

— flour, digestibility, 102.
Milk, comparison with other foods, 117.

— composition of, 78, 117, 143.

— curdling of, 145.

— digestibility, 102.

— diseases of, 145.

— loss by sale of, 78.
Milking cows, diet for, 130.
Muscular force, 80, 119.
Mustard, 72.

NATURAL vegetation, 30.
Nitrate of sodium, 36, 43-45.
Nitrates, conservation of, 25, 65, 68, 72.

— loss by drainage, 25, 44, 64,

68, 72.

— produced in soil, 10, 23, 25,

36, 44, 64, 65.
Nitric acid in air, 17.

— — in rain, 17.
Nitrification, 10, 23.
Nitrogen, accumulation in soil, 30, 52,
56, 65, 66.

— assimilated by tubercles, 10.

— in animal products, 78.

— in rain, 17.

— in soil, 22.

— losses of in rotation, 71.

— obtained from the air. 10, 66,

73.

Nitrogen, stored up by animals, 136.

— voided by animals, 136.
Nitrogenous matters assimilated \

plants, 9.

— tissue, waste of, 81, 12C
Nutrition of animals, 80.

— of plants, 4, 8.

OAT crop, 48, 50, 60.

— grain, composition of, 88, 139.

— — digestibility, 97, 100.

— — feeding value, 107, 109, 1 1

132.

— — manure value, 139.

— straw, composition of, 88, 140.

— — digestibility, 97.

— — manure value, 140.
Oil, influence on digestion, 105.
Oilcakes, composition of, 88, 139.

— advantages of use, 112, 129.

— manure from, 139, 140.
Olein, 76, 144.

Oxen, albuminoid ratio for, 128.

— ash of food stored up and voidc

136.

— carcase in live weight, 79.

— comparison with cow, 131.

— composition of, 77, 78.

— digestion of food by, 97.

— excrements of, 138.

— maintenance diet for, 121.

— manure from, 124, 133, 138.

— nitrogen of food stored up ai

voided, 136.

— results of fattening, 124.
Oxidation in plants, 7.

— in soils, 23.

PALMITIN, 76.
Palm-kernel meal, 132, 139.
Pancreatic juice, 84.
Pasture, 52, 65.

— gain of nitrogen by, 66.
Peas, composition, 88, 139.

— digestibility, 97, 102.

— feeding value, 107, 109, 111.

— manure value, 139.
Peat, 134.

Peat bog, 24.
Peat moss, 134.
Pectin, 2, 82, 89.
Pepsin, 84.
Peptones, 84.
Perennial plants, 15.
Perspiration, 85, 129, 137.
Phosphates, ground, 38.

— reduced, 39.

INDEX.

159

Phosphates, soluble, 39, 40.
Phosphoric acid, absorption by soil, 26,
40.

— — in animal products, 78.

— — in crops, 48, 49.

— — in foods, 139, 140.

— — in soil, 9, 22, 26, 40.

— — lost in rotation, 71.
Pigs, albuminoid ratio for, 128.

— ash of food stored up and voided,

136.

— carcase in live weight, 79.

— composition of, 77, 78.

— composition of increase, 79.

— digestion of food by, 101.

— manure of, 133.

— nitrogen of food stored up and

voided, 136.

— results of fattening, 124-127.
Plant assimilation, 4, 8, 9.

— constituents, 1.

— development, 12, 14.

— excretion, 11.

— respiration, 7.

— transpiration, 8.
Potash in animal products, 78.

— in crops, 48, 49.

— in foods, 139, 140.

— in soils, 22.

— lost in rotation, 7 1 .

— manures, 42, 4o, 46, 52, 54, 55,

59.
Potato crop, 49, 55.

— manure, 40.

Potatos, composition of, 49, 88, 140.

— digestibility, 102.

— feeding value, 107, 109.

— manure value, 140.
Ptyalin, 84.

BAIN-WATER, 17.
Eape, 68, 72.
Rapecake, 132, 139.
Reduced phosphates, 39.
Rennet, 150.
Respiration of animals, 85.

— of plants, 7.

Rice meal, 88, 97, 107, 109, 111, 139.
Ripeness as affecting composition, 14,

93.

Ripening cream, 148.
Rocks, disintegration of, 18, 22.
Root crops, 49, 54, 68.
Roots, functions of, 8.

— union with fungi, 10.
Rotation of crops, 63.

losses during, 70.

Rotations, economical, 73.
Ruminants, digestion by, 97.
Rye, 50, 72, 8», 140.

— bran, digestibility of, 10-.

SAINFOIN, 61, 68.

Sale of produce, 70, 73, 78.

Saliva, 84.

Salt, common, 18, 42.

— effect on digestion, 106.
Sand, 18, 20, 21.

Sap of plants, 4, 7-9, 11, 15.

Sarcine, 76.

Sawdust, 134.

Scotch pine, 49, 55.

Season, influence of, 14, 59, 93.

Seaweed as manure, 33.

Seeds, depth of sowing, 13.

— germination of, 12.
Shallow-rooted plants, 68.
Sheep, albuminoid ratio for, 128.

— ash of food stored up and

voided, 136.

— carcase in live weight, 79.

— composition of, 77, 78.

— composition of increase, 79.

— digestion of food, 97, 100, 103.

— excrements of, 138.

— feeding in winter, 113.

— maintenance diet for, 121.

— manure, 133.

— nitrogen of food stored up and

voided, 136.

— production of wool, 129.

— results of fattening, 124.
Shoddy, 37.

Silage, 95.

Silica in plants, 3, 11, 12,50, 69.

Silicates in soil, 18, 22, 27, 29, 50.

Skim-milk, 148.

Skin, its functions, 85, 86, 129, 137.

Soil, absorptive power of, 26.

— burning, 29.

— constituents of, 18.

— movements of salts in, 24.

— origin of, 18.

— oxidation in, 23, 64.

— plant food in, 21.

— relation to heat, 21.

— — to water, 20

— virgin, 30.

— weight per acre, 22.
Soluble phosphate, 39, 40.
Soot, 37.

Sow's milk, 117.
Special manuring, 57.
Spruce fir, 49, 55.

160

INDEX.

Starch in plants, 7, 13, 15.

— influence on digestion, 105.

— in foods, 82, 89-91.

— heat-producing value, 83, 108.

— part in nutrition, 82.

— work-producing value, 1 22.
Stearin, 76, 144.

Stomach, 84, 96.

— proportion in ox, 125.

pig, 125.

— sheep, 125.

Stones, 21, 22.

Storage of food in plants, 14.
Straw as litter, 32, 134.

— of crops, 14, 44, 48, 50.

— composition of, 48, 88, 140.

— digestibility of, 97, 101, 104.

— feeding value, 91, 107, 109, 111.

— manure value, 140.

Sugar, heat-producing value, 83, 108.

— influence on digestion, 105.

— in plants, 7, 13, 15.

— part in nutrition, 82.
Sugar of milk, 144.

Sulphate of ammonium, 35, 44, 45, 51.
Sulphates in rain, 18.
Sulphocyanates, 35.
Superphosphate, 39, 43, 51, 57, 72.
Swartz's mode of raising cream, 146.
Swede crop, 49, 54, 71,
Swedes, composition of, 88, 140.

— digestibility of, 99.

— feeding value, 107, 111.

— manure value, 140.

TAN, spent, 134.

Temperature, influence on animals, 80,
119, 123.

plants, 5, 59,
60.

soil, 21, 24,

61.

Thomas' slag, 38.
Tillage, effects of, 24, 28, 62, 65.
Timber, composition of, 1, 49, 56.
Top-dressing, 43.
Training, influence of, 120.
Transpiration of water, 8, 11.
Trees, food stored up in autumn, 15.
Trvpsin, 84.

Tubercles on leguminosae, 10.
Turnip crop, 49, 54, 58—61, 68, 73.

Turnips, composition, 88, 92, 95.

— digestibility, 99.

— feeding value, 107, 111, 114,

132.

— manure value, 140.

— winter feeding of, 113.
Tyrosine, 89.

UREA, decomposition of, 32, 141.

— formation of, 81, 85.
Urine, 85, 137-139.

WARMTH of soils, 21.

Waste in drainage water, 24, 36, 44,

64, 72.
Water for animals, 92, 113.

— influence on food, 113.

— relations to soil, 20, 24-29, 64.

— relations to vegetation, 1, 4, 6,

8, 59.

Weeds, 62.

Well water, nitrates in, 72.
Weekly results during fattening, 124,

Wheat bran, composition, 88, 139.

— — digestibility, 97.

— — feeding value, 107, 109.

Ill, 131, 132.

— — manure value, 139.

— crop, 48, 5U, 57-61, 63, 68, 69.

— gram, composition, 48, 88, 139.

— — food for sheep, 129.

— — manure value, 139.

— straw, composition, 48, 88, 140.

— — digestibility, 97,
" edinj
111.'

ility, 9
value,

107, 109.

— — manure value, 140.
Whey, 153.

Winter, influence on crops, 61.

Wood ashes, 42.

Wool, composition of, 78, 129.

— production, 76, 81, 129.

— suint (yolk) of, 76, 129.
Woollen refuse, 37.

Work, external, 119.

— internal, 119.

— production of, 120, 122.
Worms, 23, 29.

YOLK (suint) of wool, 76, 1 29.
Young animal, nutrition of, 116.

THE END.

MORTON'S HANDBOOKS OF THE FARM.

THE aim of the Series is to display the means best calculated to secure
an intelligent development of the resources of our soil, and, with the
assistance which advanced Chemical investigation provides, to direct those
engaged in Agricultural Industry towards the most successful results. The
Series will be helpful equally to the Teacher and ihe Student in Agriculture,
no less than to the Farmer — dealing in its course with the CHEMISTRY
OF THE FARM; THE LIVE STOCK AND THE CROPS; THE SOIL
AND ITS TILLAGE ; and the EQUIPMENT OF THE FARM OR THE
ESTATE. Each book is complete in itself, and the ehort Series of handy
volumes, by various writers. Vvho have been specially selected, forms a
complete HANDBOOK OF THE FARM, which is abreast of the enterpris-
ing man's every-(iay requirement?, and enables him economically to utilite
the advantages which an ever-wideuing science places within his reach.

No. I. CHEJVIXSTJEfcY OF THE
F./&.RRX.

BY E. WAEINGTON, F.K.S.

Sixth Edition Revised and Enlarged.

No. II. LIVE-STOCK..

BY W. T. CAREINGTON, G GILBEET, J. C. MOETON. GILBEET MUEEAY,
SANDEES SPENCEE, AND J. WOETLEY-AXE.

No. III. THE CROPS.

BY T. BOWICK, J. BUCKMAN, W. T. CAEEINGTON, J. C. MOEGAN,
G. MUEEAY, AND J. SCOTT.

No. IV. THE SOIX*.

BY PROFESSOR SCOTT AND J. C. MOETON.

No. V.

BY MAXWELL T. MASTEES, F.E.S.

No. VI. EQTJIFMEKTT.

BY WM. BUENESS, J. C. MOETON, AND GILBEET MUEEAY.

No. VII. THE

BY JAMES LONG AND J. C. MOETON.

No. VIM.

BY PROFESSOR BROWN, C.B.

No. IX. XjuAJBOUR.

BY J. C. MOETON.

In crown 8vo volumes, price 2s. 6d. each, or the complete

set of nine volumes, if ordered direct from the

office, carriage free, for £1.

VINTON & CO, Ltd, 9, New Bridge St., London. E.C.

AGRICULTURAL GAZETTE.

THE PRACTICAL FARMER'S PAPER.

ESTABLISHED 1S44.
MONDAY, TWOPENCE.

THE AGRICULTURAL GAZETTE has for many years, by general consen
stood at the head of the English Agricultural Press. It is unequalled as
high-class Farmer's .paper, while the price — TWOPKNUU weekly, or post frt
10s. lOd. per whole year — places it within the reach of all farmers. All branch
of farming — crops, live stuck, and dairy — are fully discussed by leading practic
authorities. Market intelligence and reviews of the grain and cattle trades a
s pecial features. Prompt replies given to questions in all departments of f armtn
Veterinary queries answered by a qualified practitioner.

Rates of Subscription— 3 Months, post free, 2s. 9d. ; 12 Months, Ws. Wd.

LIVE STOCK JOURNAL

FRIDAY, (Illustrated.} FOURPENCE,

ESTABLISHED 1874.

THE only Paper in the British Islands that is wholly devoted to th
Interests of Breeders and Owners of all varieties of Live Stock
Contains contributions from the higrhest authorities on all matter
relating- to the Breeding-, Feeding-, & Veterinary Treatment of Domes
ticated Animals, and Illustrations of the more celebrated specimen
The " LIVE STOCK JOURNAL " gives the fullest and earliest reports o
Agricultural Shows, Stock Sales, Sheep Sales and Lettings, whilst its Herd an
Plock Notes and Notes from the Stables contain much valuable and interesting in
formation. Prominence is given in the columns of the JOUIINAL to correspom
ence on all questions of interest to Country Gentlemen, Breeders, and Exhibitor
Rates of Subscription— 3 Months, post free, 5s. ; 12 Months, 19s. 6d.

EAILY'S

OF

SPORTS AND PASTIMES.

RACING, HUNTING, SHOOTING, YACHTING, ROWING, FISHING,
CRICKET, FOOTBALL, ATHLETICS, &e.

THIS well-known monthly contains articles written by the bett authorities
on every phase of British Sport ; and, in addition to the usual Frontispiece
— a Steel Plate Portrait of an eminent sportsman — other Illustrations of weM
chosen subjects and of the highest artistic merit are given.

Of all BooV sellers and at al). Bookstalls, One Shilling.
Or by Post direct from the Office, 143. per year.

India Proofs of any of the 400 Portraits which have appeared, 2s. 6d. each

VINTON & CO., Ltd., supply all works on Agriculture and kindred subjects
post free on receipt of published price.

VINTON & CO., Ltd., 9, New Bridge Street, London, E.G.

2

cr»

0)

<*-<

o

•1-1

t

UNIVERSITY OF TORONTO
LIBRARY

Acme Library Card Pocket

Under Pat. " Ref. Index File."
Made by LIBRARY BUREAU