THE COMPLETE FARMER

SOILS

THEIR NATURES'

TREATMENT

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U.B.C. LIBRARIES

I UNIVERSITY OF
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I COLUMBIA

Duncan S. Gray

Digitized by the Internet Archive

in 2010 with funding from

University of British Columbia Library

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THE COMPLETE FARMER

SOI LS : Their Nature

Management

PRIMROSK McCONNELL

Other Volumes of
this Series

will consist of a treatise on
each of the following subjects :

Crops

Live Stock
Dairy
Equipment

Paper Covers, Is. net each ;
Cloth, Is. 6d. net

CASSELL & CO., Ltd., London

PHOTOGRAPHIC VIEW OF A SOIL SECTION, SHOWING UNDERGROUND

layers {see page 8).

SOILS* Their Nature

Management

A PRACTICAL HANDBOOK

BY

PRIMROSE McCONNELL, B.Sc.

Fellow of the Geological Society, Fellou: of the Highland and Agricultural

Society of Scotland, Examination Member of the Royal Agricultural

Society of England. A uthor of " Notebook of A gricultural

Facts an I Figures," "Elements of Farming,'

■'Agricultural Geoiogy," "Diary of a

Working Farmer," etc. etc.

FARMER, NORTH WYCKE, SOUTH MINSTER, ESSEX

ILLUSTRATED

CASSELL & COMPANY, LIMITED
London, Paris, NewYork, Toronto & Melbourne

1908

ALL RIGHTS RESERVED

PREFACE

During the last few years the progress in the study of
science applied to farming has been very great, and the
number of farmers and farm students who have taken
the matter up is ever on the increase.

It is believed that a summary of information on
scientific practice might be usefully offered to those
interested — whether young or old — hence the present
series of Handbooks, of which the first is now issued.
The series will consist of separate volumes on Soils,
Crops, Live Stock. Dairy Farming, and Farm
Equipment, and each will be complete in itself. The
subjects will be treated in a simple manner, without
introducing many technicalities, and the volumes will
'form a complete treatise on modern scientific farming.

The author is himself farming extensively, and has
sifted all the information through his own practical
experience. In many cases farmers from long training
instinctively form their judgments and ideas on anything
connected with the farm without any conscious reason-
ing on the matter : in these volumes the scientific know-
ledge behind the practical work will be explained, so
that the learner may understand the reasons of all the
complex phenomena he meets with on a farm, and may
thus in the future develop his farming on a sound
scientific basis.

CONTENTS

CHAPTER I.— THE SOIL ITSELF

I,

— Origin

PAOB
1

II.

—Formation . .

*.*

1. Water .

4

2. Frost

5

3. Chemical Action ...

6

4. Plants

6

5. Earthworms . . • .

i

6. Microbes

7

III.

—Composition .

8

1. Structure

8

2. Proximate Constituents ....

10

3. Organic and Inorganic Parts

12

4. Chemical Composition ....

12

."). Soluble and Insoluble Ingredients .

15

IV.

-Classification

15

V.

I ►iSTBIBUTION

17

1. Primary Formations

17

2. Secondary Formations ....

19

3. Tertiary Formations

2]

4. Quaternary Formations ....

21

5. Kecent Formations

22

VI.-

-Fertility

23

x CONTENTS

CHAPTER II— THE PHYSICS OF THE SOIL

I. — Size of Partk les
II— Porosity
III.— Texture .
IV.— Tenacity
V. — Retentiveness
VI.— Depth
VII.— Weight .
VIIL— Colour .
IX.— Odour
X. — Ventilation
XI.— Moisture

1. Percolation

2. Capillarity .

3. Evaporation
XII.— Temperature .

XIII.— Tilth

PAOE

26
28
29
30
31
33
34
3G
37
37
39
39
40
42
42
47

CHAPTER III.-THE PHYSICAL CEOGRAPHY OF
THE FARM

I. — Latitude

50

11. — Altitude

51

III.— Climate

52

IV. — Rainfall and Water Supply

53

V. — Shelter . . . .

56

VI. — Aspect

57

VII. — Contour

59

VIII. — Sea Influence

61

IX.— Natural Vegetation

m

CONTENTS

CHAPTER IV.— THE IMPROVEMENT OF THE SOIL

I. — Draining

II.— Stone Clearing
III. — Liming .
IV. — Irrigation

V. — Manuring

PAGE

66

71
73

77
80

CHAPTER V.— THE TILLAGE OF THE SOIL
I. — Ploughing

1. Bare-fallowing

2. Subsoiling .
II. — Cultivating .

III.— Harrowing .

IV. — Rolling .
Conclusion ....
Index

86
88
90
92
95
96
99
101

LIST OF ILLUSTRATIONS

Photographic view of a Soil Section, showing Underground
Layers ....... Frontispiece

FIG. PAGE

1. — Section of a Hill showing Poor. Thin, Stony Soil at a, and

Good Loamy Soil at B : Stream, at c . . .5

2. — Section of Soil showing Underground Layers . . .9

3. — Microscopic Section of Arable Cla\--loani Soil showing Particles 27

4. — Position of the Water-table in a Hill, and the Occurrence of

Springs ......... 40

5. — Variation in the Percentages of Capillary Water in the Soil

between two Pipe-tile Drains . . . . .41

6. — Diagram of Monthly Soil Temperature at Half a Foot, Three

Feet, and Six Feet Deep ...... 4d

7. — Aspect .......... 58

8. — Catchwork Irrigation, showing Contour Furrows cut across

the Slope to Catch Downward Flowing liquid Manure . 79

9. — Plough, with Subsoiler attached . . . . . 91

10. — Royal Agricultural Society's First Prize Cultivator . 93

SOILS: THEIR NATURE

AND MANAGEMENT

CHAPTER I.— THE SOIL ITSELF

The soil is the most important part of a farm ; therefore it natur-
ally comes first in the estimation of a farmer, and everything in it, on
it, or about it, are so many subsidiary matters which add to, or
detract from, its value. Soil may be defined as the earthy matter
which usually (but not always) forms the surface of the land, and
which we often speak of in general terms as mould, dirt, earth, etc.
It is for the soil that a farmer pays rent to the owner, and the price
is usually reckoned at so much per acre — high or low according to
its inherent quality and surrounding circumstances.

During the last generation or so the study of the soil itself has
been very much developed and extended, and we know a great deal
more about it scientifically and apply our knowledge more practi-
cally than our forefathers did. An inquiry into the subject may be
conveniently grouped under (1) Origin, (2) Formation, (3) Composi-
tion, (4) Classification, (5) Distribution, (6) Fertility, and we can
proceed to discuss each in turn.

I. — Origin

At one time in the history of this earth of ours, the surface of
the dry land was entirely devoid of soil, and nothing was exposed on
the top excepting hard rocks of various kinds. Indeed, there are
many parts of the earth now — in patches in some districts, in
great regions in others— where there is still no soil at all, and where,
under present conditions of land, water, climate, etc., there is not
likely to be in the future. The soil had an origin, and we can see with
our own eyes how it originated and came to cover the greatest part

B

2 SOILS : THEIR NATURE AND MANAGEMENT

of the habitable globe, for the making of soil is going on all around
us at the present day.

The origin whence every soil has been derived— with one or two
exceptions which will be mentioned presently— is the rock material
that comprises the crust of the earth, and the endless varieties of
which give rise to corresponding variations among the soils derived
from them. Rocks are composed of minerals, and minerals are in
the great majority of cases definite chemical compounds, and it is
from these primarily that most of our soils have been derived.
There are several hundreds of kinds of minerals known and classified
by mineralogists, but only about six or seven are of the first import-
ance as the origin of soil material. These are as follows : —

Felspar, Quartz, Mica, Calcite (Limestone), Hornblende, Augite,
and Kaolinite (Clay).

Felspar is the most widely distributed mineral, forming nearly
half of the solid rock crust of the earth. It may be described as a
double or triple silicate of alumina combined with potash, soda, or
lime. Common clay is one of the products derived from it by ordinary
weathering (kaolinisation). Soils which contain some undecom-
posed felspar in their composition have a great reserve of plant
mineral food.

Quartz or silica is the hard, glassy mineral which forms the
bulk of such bodies as sand, sandstone, and flint, more or less
coloured by iron or other substances. It never changes in chemical
composition, as the others do, from weathering. As ordinary sand
it is one of the most important components of a soil, and under the
microscope appears as rounded, waterworn, translucent grains. In
clayey soils, however, it often occurs as "flour," i.e , exceedingly
fine particles just as it was set free by the weathering of a rock.

Mica is also a double silicate of alumina with potash, magnesia,
lime, or iron, but it does not easily weather down. Mica occurs as
thin, shining, elastic plates, found in granite, mica-slate, etc., and it
forms the small shining scales in various sandstones and soils.

Calcite is the name given to pure crystalline limestone. In one
way or another lime forms the bulk of all our limestones, oolite and
chalk hills, and in the weathered form is found in marl and soils.
It is one of the most important components of the soil, partly
from its manurial and partly from its chemical value.

Hornblende and Augite are silicates of lime, magnesia, and
iron, without potash, soda, and alumina for the most part, and
constitute the greater part of the dark green or black minerals
met with in rocks. These silicates are the origin of most of the

THE SOIL ITSELF

magnesia, iron, and lime met with in ordinary soils, and, therefore,
are an important source of their "inherent fertility," while the iron
from these silicates is the chief colouring agent in earthy
material.

Kaolinite (Clay) is really a "secondary" mineral, that is, one
derived from the weathering or other modification of another
mineral, principally felspar, as before mentioned. In its purest
form, as kaolinite or china clay, it has the definite chemical com-
position of hydrated silicate of alumina (ALO, + SiOa + 2H20).
It is sticky and plastic to handle, and the stickiness is considered
to be due to the presence of a "colloid " (jelly-like) form of silicate
of alumina which may be present to the extent of 1'5 per cent.
When a piece of clay is dried and burnt the water of combination
is driven off, its plasticity is lost and it becomes " set," or hardened,
as exemplified in a burnt brick.

It is from these bodies principally that the mineral part of our
soils and subsoils have been derived, and the great bulk of most
every one is composed of the debris of these bodies.

As the surface of the globe was at one time devoid of soil, the
question of age arises, and we naturally want to know when the soil
was made. There must have been an innumerable succession of
soils throughout geological time, taking the world as a whole, but
for the British Islands the evidence goes to prove that at the close of
the Great Ice Age, some 10,000 years ago, the wreckage left by the
ice was the first material on which our soils began to be formed,
and the work has been going on continuously ever since.

There is a constant washirig away into the streams and out to sea
of soil material, either in the shape of solid silt held in suspension
in Hood times, or various salts carried in solution at all times, though
this wastage is being constantly renewed by the further breaking
down of rock and mineral matter or the growth of vegetation. It is
computed that the whole surface of the country has been lowered by
about one foot in a thousand years, and as the suil still remains, and
keeps approximately the same, it must be continuously renewed, and
therefore no specific age can be given to it, though a limit can be
fixed to the beginning of the original formation.

II. — Formation

Soil formation out of the materials before mentioned is largely
process of " weathering," but as the action of the weather is a

1 SOILS : THEIR NATURE AND MANAGEMENT

complicated process the different agencies comprised in the
term, in addition to many other factors, had best be studied
separately.

1. Water.— Assuming that we have got a fresh surface of bare
rock to begin with, the first thing that happens is that it gets wet
with rain. Water will soak into the hardest and closest grained
rock, and this wetting leads to a number of changes. It dissolves
out any soluble salts it meets with, and even some material
usually considered insoluble, thus helping to loosen the mineral
particles. When the rain falls in sufficient quantities it forms
streams which not only help to wear off debris from any surface
it runs over, but also carries the same downwards and deposits it
elsewhere. This "rain-wash," as it is termed, is sometimes a source
of much injury to a soil already formed, for any loose material lying
on sloping ground is certain to be carried downwards to the
bottom of a field or into the nearest river.

Where there is no rain-wash or flooding, but only sufficient
moisture to keep the materials wet, these particles accumulate on
the spot and help to form the subsoil and then the soil proper
in time.

The disintegrated material must accumulate somewhere, and if
the surface is fairly level and there is little rain-wash, it will remain
where formed. This very seldom happens, however, for the rain
which helps to make it also tends to carry it downwards to the
streams, especially in flood time, and thus the debris accumulates
in the hollows, along the levels of the valleys, on places where the
land is not too steep, or is carried out to sea.

This debris is not yet soil, however, but only its mineral matter
(subsoil) and requires a lot more modification before it is fit to
carry ordinary vegetation or the crops of the farm.

In connection with the action of running water is the question
of the formation of soils in situ qr by transportation of the
material, and it is here necessary to correct a common erroneous
impression concerning such formation. All soils have been formed
where we now find them, with one or two exceptions that will be
specified immediately. The eroded material (i.e. the subsoil) out of
which the soil has been formed may have been brought from
a distance — like the boulder clay, for instance — or may be
native to the spot on which it is found ; but the point to bear
in mind is that the soil has been formed out of, and on, this
material where we now find it. The only exception to this is
the case of alluvial soils and others of that class, like the

THE SOIL ITSELF

" Warp-land." These have been formed mostly from the washings
of soils already made higher up the streams, and so constitute
"transported soils" in the proper sense of the term.

Even in an ordinary field this constant transportation is going
on. If there is the slightest slope the mere action of gravity,
aided by the rain in a wet time, will gradually work the finer
earth downwards, and thus we find as a rule that the sandiest or
stoniest part of a field is at the top and the finest soil at the
bottom : in other words, the most fertile part is the lowest.

Yic. 1, — Section of a Hill showing Poor, Thin. Stony Soil at A,
and Good, Deep, Loamy Soil at B; Stream at 0.

Apart from the action of the rain-wash, the soil seems to work
its way bodily downwards on a sloping surface, leaving the top bare
and the good soil crowded up against the bottom fence. (See Fig. 1.)

2. Frost. — As soon as the moisture soaks into any body it is
liable to freeze on the advent of winter. Now, freezing expands
the water, and thus scales, lumps, or blocks get split off and all help
to swell the bulk of broken mineral.

The process may take a long time, but it is accomplished sooner
or later, as we can see by the wearing away of our brick walls or old
stone buildings.

Apart from the action of frost in the original manufacture of the
soil, there is the effect of frost every winter on the soil already made,
liy freezing the moisture in the soil the particles are still further split
up, lumps are broken down, the sticky action of the colloid part of
the clay is temporarily checked, and when the frost departs, and the
moisture dries, the soil is left in a fine, mealy or "tilthy " condition,
exceedingly fit for seeding or cultivating. This process is much
superior to any artificial preparation.

There is a limit, however, to the action of frost in breaking up

G SOILS : THEIR NATURE AND MANAGEMENT

rock fragments and promoting the disintegration of them, and it
would seem that the sand or other particles in an ordinary sample
of soil have reached this limit. At any rate, the action of the frost
on an ordinary soil (already formed) does not increase the soluble in-
gredients in it. The converse of the frost — the sun's heat in summer-
time— has also a considerable influence. In a hot summer the
ground contracts and cracks, and each crack supplies a new surface
for the action of the disintegrating forces. Even the solid, rocky
material is known in many cases to split up from the expansion and
contraction of its material due to the change of temperature
between the cold of the night time and the heat of midday. As the
mineral ingredients have often different degrees of expansion, the
effect of change of temperature is still more enhanced.

3. Chemical Action. — Continuously acting with the changes of
temperature, etc., is the oxidising or rusting influence of the oxygen
of the atmosphere. Most mineral material contains iron in its
structure as one of the " cementing " constituents, and when this
oxidises or " rusts," the cementing power is destroyed and the other
materials fall to pieces as an amorphous powder.

Another chemical disintegrating agent is water containing some
carbonic acid gas in solution. As there is always some of this gas in
the atmosphere the rain takes it up in falling, while any decaying
vegetation in the surface soil will also yield some. Thus rainwater
in percolating through a rock or other ground material gets charged
with carbonic acid gas. Now acid-charged water has great dis-
solving power on iniuerals containing lime, potash, soda, etc.. and
when these bodies in the course of years dissolve out— as happens
very largely with calcareous rocks — the residue again becomes
broken up into earthy debris, thus adding to the bulk of disinte-
grated material.

4. Plants. — A further modification in the making of a soil is the
accumulation of vegetable matter or humus in the top layer, and
this begins first by the growth of the lower forms of vegetation, such
as lichens and mosses. These can grow direct on a fresh rock surface
and extract nutriment for themselves out of the raw mineral
material and the atmosphere. The decay of these furnishes a
certain amount of organic matter which mingles with the rocky
</<'/>/-is, and thus the first beginnings of a soil proper are made which
in time becomes fit to carry plants of a higher organisation.

When the vegetable matter accumulates in excess, so as to form
the bulk of the soil, we have a peaty formation, an exception to the
rule of the formation from the disintegration of mineral matter.

THE SOIL ITSELF 7

Peat pure and simple lias mostly been formed by the growth of
Mosses {Sphagnum, Hypnum, etc.), in swampy places in a cool
climate, and most hollows in the districts that form the west and the
north of these islands are more or less filled up with this vegetable
organic humous formation.

When plants of a higher order occupy the ground their roots
penetrate all crevices and fissures in the rock or soil material,
and by their expanding growth split up the rock into smaller
pieces, and thus promote disintegration in another way. Again
the fine rootlets or root hairs secrete various " organic " acids which
have the power of dissolving out the mineral food of the plants,
ready for absorption by them. This is most strongly developed
in lichens and mosses, and it has been shown that even in our
farm crops the solving power is ecpual to a one per cent, solution of
citric acid. Its effect can be demonstrated in the case of beans by
putting" earth on a polished marble slab, sowing the seed and
growing some plants ; when the slab is afterwards washed it will be
seen that the roots ate tracks for themselves on the marble by their
acid power.

5. Earthworms. — Darwin has shown that our surface soils have
very largely been made, or at least, modified, by the action of the
earthworms that live in them. These animals live on the vegetable
matter in the soils, and to obtain it they ingest large quantities of
the finer earth. This is passed through their bodies and thrown
on to the surface as worm-casts, and the work of disintegration of
the particles is greatly furthered by their action. They bring up
this material from the lower layers, and it is computed that on
an ordinary undisturbed grass field this fine material is thus
deposited to the depth of one inch every five years.

In addition to this disintegration, worms are continually drag-
ging dead leaves, straws, etc., into their burrows, and thus adding
directly to the organic matter in the soil. Their burrows also are so
many downward channels which help in the percolation of water,
the entrance of air, and the spread of plant roots.

6. Microbes. — The soil is not the dead, inert body that it was
once believed to be, but is full of living creatures, one class of which
— bacterial life— is of the utmost importance in the original forma-
tion and continuous modification of its contents. A whole host of
these have been isolated and described, and their life-history is now
known. The transformation of plant tissue into the humic or
organic portion of the soil is largely the result of microbic life. The
development of various acids isuch as nitric, carbonic, humic.

8 SOILS : THEIR NATURE AND MANAGEMENT

ulmic, etc.) is due to the action of various kinds of Micrococci,
Bacilli, etc., on the humous part. These live in the top soil and as
deep down as eighteen inches, and their life-work is of the utmost
importance in connection with the fertility of the soil and the
practice of manuring, as will be explained in the proper place.
Attention is drawn here to the part they play in making the soil.
Their influence is largely one of oxidation, but the acids they
develop have a certain amount of "corrosive'" action whereby the
process of disintegration of soil material is promoted. The study of
the bacterial life of the soil has developed very greatly during the
last few years, and is one of the most important recent advances in
the application of science to farming.

III. — Composition

Very early in the study of the soil we have to take up the
question of its composition, and how the parts are put together.
We may do this under five different aspects or classes : (1) Structure,
(2) Proximate Constituents, (3) Organic and Inorganic parts, (4)
Chemical Composition, (5) Soluble and Insoluble Ingredients.

Each of them is of course related to and dependent to some
extent on the others, but each represents a separate point of view,
influencing the practical farming of any particular field or piece
of soil, and we may take them up in order.

1. Structure. — If we examine a section of the ground laid bate
by digging where it has not been disturbed by artificial means— as
on an old pasture field— we find it is composed of several layers, and
these layers always occur in the same order, no matter what kind of
a soil it is or in what part of the world it is found. Though in
some cases one or more of the layers may be completely wanting,
yet the order of occurrence always remains the same. {See
Fig. 2.)

On the top we find first of all a grass or vegetable layer
about three inches thick. It is remarkable how constant this thick-
ness is throughout the world wherever a soil is found, and it may
be looked upon as the minimum depth on which grass — the
natural vegetation— will grow, as it is indeed just the thickness
of a sod or a turf.

Below this comes the soil proper, from a few inches to over
one foot in depth, and this, in common with the top sod, is dis-
tinguished from the lower parts by its darker colour. Next to
the soil proper is the subsoil, which may be wanting altogether ;

THE SOIL ITSELF

!)

and in other cases may extend downwards to a great depth. It
is not so dark in colour as the soil proper, being often a light
brown or yellow, while the soil on top is a dark brown. , Below
the subsoil, in the majority of cases, comes the "brash'' or
rubble, composed of a mixture of broken rock and subsoil.

Lowest of all is the solid rock itself, hundreds of different kinds
of which are found in the world, and from these the overlying soils
and subsoils take most of their characteristics.

These different layers vary in thickness, but they always occur
in the same order of superposition, though some of them may be
wanting, as previously stated. In a hilly or rocky district, for

!•'[<;. 2. — Section of Soil showing Underground Layers.

instance, the subsoil and the rubble may be absent and the soil rest
directly on the rock, or the subsoil may be wanting and the soil
overlay the rubble, and so on.

The face of the ground exposed in a quarry or railway cutting
will always show some, if not all, of these component layers of
the "soil," and in this connection it may be explained that in
a geological sense every solid substance composing the crust of the
earth is a " rock," so that in this way a clay formation may be the
underlying "rock" of a district, and the subsoil and "brash"
or rubble insensibly grade into this without any distinct lines of

10 SOILS : THEIR NATURE AND MANAGEMENT

demarcation. Sometimes, indeed, this is true of the soil itself also,
and there is no visible difference between the top and the lower
layers. [See Frontispiece.)

There is one more point connected with the structural composi-
tion of soils worthy of note, and that is the existence in some soils
of a " pan " at a short distance from the surface. The continual
percolation of water downwards tends to wash compounds of lime or
of iron down from the top, and in the course of ages this material
has been re-deposited at a depth of from six inches to a foot. It
forms a sort of incrustation like a pavement in some soils, and as
roots cannot penetrate through it this "pan" must be broken up by
deep cultivation to improve the soil. Again, the continuous passage
of the plough through the soil at one depth year after year, and the
treading of the work-horses, have pasted up and consolidated a layer
of soil, thus forming a " plough-pan," which also must be broken
up by deeper cultivation by a farmer who intends to improve his
farm.

2. Proximate Constituents. — The second method of dividing
a soil into its component parts is that of its " Proximate Constitu-
ents." If a handful of soil is taken and examined by a magnifying
glass, or with the naked eye, it will be found that it can in most cases
be quite readily separated into various ingredients. The sand in it
will be quite distinct, also the clay, the stones, etc. Systematic
study has shown that the "Proximate Constituents " of all soils are
five in number : sand, clay, lime, humus, and stones, and the
particular varieties of these and their proportions have every-
thing to do with the capabilities of a soil for cultivation pur-
poses. It is indeed on the proportion of these visible components
that a farmer judges of the value and usefulness of a soil as
far as its mechanical condition is concerned, and it is on these
that the classification of soils is founded in ordinary practice.
Each of these constituents requires some explanatory remarks,
which are here appended.

Sand. — Sand in the pure state is quartz or silica in small particles,
and would naturally be either translucent or white from refracted
light. It is usually, however, coloured red, brown, or yellow, from
different oxides of iron in common with the other ingredients of the
soil. It is generally found in rounded grains as the result of water
wearing in bygone ages, though sometimes, when not formed of
silica, it may exist as fine plates or scales (as when derived from
mica).

Clay. — Clay, as mentioned before, is the hydrated silicate of

THE SOIL ITSELF 11

alumina. It forms the plastic, sticky part of the soil, and a pre-
ponderance of it makes the soil "heavy," that is, stiff and difficult to
work. Pure clay (china clay or kaolin) is perfectly white ; but that
in the soil is always more or less stained by the oxides of iron, like
sand. When clay is of dark or bluish grey colour it is due to the
presence of sulphide of iron or to the diffusion of carbonaceous
(organic matter.

Clay differs completely in physical characteristics from, sand, for
whereas the latter is loose and incoherent, clay is firm, plastic
and tenacious and very retentive of moisture. The particles of
clay are so small that they cannot be distinguished without a
microscope, -„,-,,-, inch being the common size.

When more than one-third of the bulk of the soil is composed of
clay, the soil becomes very heavy to work, requiring say three horses
to the plough ("three-horse land") to do ordinary work, as it is
more or less sticky, adhesive, and retentive of moisture.

Lime. — Lime in the ordinary state exists in minerals and in soils
mostly as a carbonate. Every fertile soil must contain some, even
if only a small percentage, whiie if more than four per cent, is
present it becomes visible, 'and gives a "marly " character to the
soil. It is non-plastic in its nature, and tends to make a stiff soil
more crumbly and friable if present in sufficient quantity or added
artificially.

Humus. — This is the general name given to the animal and
vegetable matters which accumulate in the soil and mix up with
the mineral ingredients. Turf may be included in the term, but
for the most part it is composed of the residue of the dead roots and
parts of plants which accumulate in it, and gradually change into
carbonaceous matter as the result of oxidation, microbe life, etc.
Peat is nearly all humus, and there is always some present in
every fertile soil. It is the body that mostly gives the dark colour
to the soil proper as distinguished from the subsoil.

Gravel and Stones. — Fragments of the original rock from which
the soil has been derived very often form part of its bulk, and are
found in the soil or lying about on its surface. These are generally
angular in shape, and they constitute a continuous source from
which more mineral debris is added to the finer parts of the soil as
the weathering action proceeds. Illustrations of this occur on some
of the Oolite formations of the Midlands and the Silurian districts in
Galloway, where the stones consist of irregular fragments of lime-
stone in one case and of slaty sandstone in the other. In the
case of gravel the stones have been carried some distance and

12 SOILS : THEIR NATURE AND MANAGEMENT

have been rounded by the action of moving water, either in
rivers or on the sea shore ; the extensive occurrence of flint-gravel
in the south-eastern half of England being the most notable
example.

Some of these proximate constituents can be very easily separated
from one another in a rough and ready process, which will enable one
to form a better idea of the characteristics of a soil. First the soil
is passed through a sieve to take out the stones and coarse particles.
Xext the fine part is shaken up in a glass or test tube with water
and allowed to settle. The coarse grit will come down first, then
the sand and finer material, and lastly the clay. These will show
themselves in distinct layers in the glass or test tube, and give the
experimenter a very good practical idea of the nature of the soil.
It is still more instructive to compare two soils together in this
way. If there is much humus present as a distinct ingredient
it will partly float and partly come down as a separate layer. If
some acid (say sulphuric) be poured on a quantity of the soil,
there will be an effervescence of carbonic acid gas from the
limestone, if present in appreciable quantity. Thus all these
constituents can be identified and their quantity or proportions
estimated with sufficient approximation to give a useful idea of the
nature of the soil.

3. Organic and Inorganic Parts. — If a given quantity of dry
soil is raised to a red heat there is a proportion of it burnt out, or
driven off as carbonic acid gas. The part that burns away is termed
the organic, and the solid mineral material left behind is the
inorganic, part of the soil. The relative proportions of these vary
very considerably in different cases. It has been explained that the
organic, or humous, part of a soil is mostly the partly decayed
residue of the plants and animals that have previously lived in the
upper layers, which has become gradually mixed with the mineral
or inorganic part. It is very largely carbonaceous in its composition,
but also contains hydrogen, oxygen, and nitrogen, though not in
fixed or definite proportions. There may be some carbonic acid
present, of course, in various mineral carbonates (such as lime) in
the soil, but in this connection it is customary to reckon all the
carbon, hydrogen, oxygen, and nitrogen driven off by burning as
representing so much organic material or humus.

A certain proportion of humus is desirable in a soil, because of
its physical influence, but it is noteworthy that a soil may be fertile
with less than one per cent, of it. On the other hand, in the case of
a peaty soil, the organic part that burns away will form by far the

THE SOIL ITSELF

18

largest proportion, rising up to perhaps 90 per cent, of the total in
some cases.

4. Chemical Composition.— When a soil is analysed by the
chemist in the same way as he analyses other things he finds
out the percentage proportion of its chemical ingredients. It has
been discovered that all the chemical bodies necessarily met with
in a soil are about a dozen in number, and while other bodies
may be accidentally present, those dozen are always found in a
normal soil. The following table gives their chemical names
and their percentage proportions in a few typical samples :—

Silica SiO-j

Alumina ALOj,

Ferric Oxide Fe*0-f

Lime CaO

Magnesia MgO

Potash Kj( )

Soda Xa..D
Carbonic Acid (Anhydride) CO-;

Sulphuric Acid ., SO3

Phosphoric Acid ., P;05

Chlorine CI

Organic matter C.H.O.N.

Combined water HL-< )

Xitrogeu in Organic matter N

92-52

2-65

3-19

■24

•70
•12

•02

traces

•07

traces

•49
■08

81-26

3,-58

:;-41

1-28

1-12

•80

1-20

•92

•09

•38

traces

5-G6

•17

gi

Marly.

6126

55 "52

14-04

5-96

4-87

.3-96

■83

11-15

1-02

■25

2-S0
1-44

} -071

—

8-77

■09

•04

•24

•38

•01

•76

11-25

10 -.50

•22

•20

65-80
6-30
6-30
1-01

•20

•01

20-08
•16

When a crop is analysed (i.e. a quantity of straw, grain, roots,
etc.) it is found to be made up of these same substances with
the solitary exception of alumina, a body sometimes, however,
met with in exceptional cases, such as in lichens, etc.

The organic matter (and water) in the above is practically the same
as would be driven off as gas by burning, and is composed of
carbon, hydrogen, oxygen and nitrogen in various proportions.
The other bodies form the bulk of the mineral or " inorganic "
part. It must be clearly understood that while these bodies
exist in the soil, and comprise its material, they do not occur
in the simple chemical form above noted, but in an endless
number of compounds. Thus, some lime and carbonic acid
will be combined together to form carbonate of lime or "lime-
stone," some of the silica and alumina will be in the form of
silicate of alumina or clay ; some of the sulphur and iron as
sulphide or sulphate of iron ; phosphoric acid as phosphate of

II SOILS: THEIR NATURE AND MANAGEMENT

lime, and so on with endless combinations. A chemical analysis
thus gives everything in its simplest chemical form, for the com-
pound ones can with difficulty be estimated.

It will be interesting at this point to note the close connec-
tion that there is between rocks and soils, and the crops that
grow on them in the nature and composition of their mineral
components. This is shown in the following table : —

Igneous Rocks.

Soils.

Per cent,
in Soils.

Plant Ash,

Silica

Silica

5 to 95

Silica

Alumina

Alumina

1 to 15

Ferric Oxide

Ferric Oxide

3 to 6

Iron

Lime

Lime

0to30

Lime

Potash

Potash

0to3

Potash

Magnesia

Magnesia

•05 to 1-5

Magnesia

Soda

Soda

0 to 1-5

Soda

Carbonic acid

Carbonic acid

0 to 45

Carbonates

Sulphuric acid

Sulphuric acid

small

Sulphates

Phosphorus

Phosphoric acid

small

Phosphates

Chlorine

Chlorine

small

Chlorine

Manganese

Manganese

traces

Manganese

Bromine

traces

Bromine

Iodine

traces

Iodine

Fluorine

Fluorine

traces

Fluorine

It is noteworthy that recent research tends to show, however, that
while a plant will be found to contain all these chemical ingredients
in its composition, they do not all appear to be necessary for its
growth or its health, but are absorbed by the roots out of the soil
and held by the plant, as extraneous bodies, simply because it can-
not help itself — for the roots suck up all soluble salts in the soil that
it comes in contact with. The most important of these are seven in
number : nitrogeu, phosphoric acid, potash, lime, ferric oxide,
magnesia and sulphuric acid. If there is a sufficiency of these
present as soluble compounds the others may be left out of account
as far as the crops are concerned, though they all help to form the
bulk of the soil.

It can easily be understood by anyone who has the slightest
knowledge of chemistry, that in a body like the soil, composed of so
many chemical elements, there will probably be an endless number
of chemical actions and reactions taking place. As a matter of fact
the original formation of the soil and the modifications of it are
really chemical actions in their ultimate effects, whether brought
about by weathering, by microbe life, or by the application of

THE SOIL ITSELF 15

chemical manures. Unfortunately we do not yet know exactly
what happens in this way in the soil, and can only conjecture from
the known laws of chemical action. We are certain such changes do
take place, but we can only judge of them by their practical effects
on the soil and the crops it grows.

5. Soluble and Insoluble Ingredients.— If a quantity of
soil is soaked in water and thoroughly mixed and stirred up for
some time, a small amount of soluble salts are dissolved out. If
this water is filtered off and then evaporated to dryness, the saline
matter will show itself as a small quantity of white crystalline
powder. This powder is the soluble part of the soil and the
remainder is the insoluble. It forms a very small part of the whole,
seldom reaching as much as a quarter of one per cent, of the total,
though even this small quantity amounts to a lot on an acre or a
field. As an inch in depth of soil equals over one hundred tons per
acre it follows that in every inch in depth there may be as much as
five cwt. of this soluble material, or about two tons per acre in the
first eight inches of depth.

This soluble material is the immediate mineral food of the plants
or crops growing on the soil, and it is mainly because of its
limited amount that we require to help matters by applying
manures. As detailed before, however, the acid reaction of the
living roots themselves enables them to dissolve out some more
matter for their own direct use, so that probably double the above
quantity of material is at the service of the crops. This acid
reaction is reckoned as equal to a one per cent, solution of citric
acid, and therefore if the soil in the above test is treated with a one
per cent, solution, the resultant saline matter obtained will represent
what is really available. The action of all the weathering and other
agents, which helped to originally form the soil, continues to set free
furthej portions of "soluble" material as the years go on, but the
total soluble constituents remain fairly constant.

In an ordinary chemical analysis, strong acid — such as hydro-
chloric— is used to dissolve the materials, and in this way "soluble "
matter may be obtained up to six, eight, or ten per cent., the
remainder being " insoluble sand or clay," forming the balk of the
soil, but never supplying food to plants. Nowadays, however, it is
usual to treat the soil with a two per cent, solution of citric acid, so
as to test what is actually available and what will easily become
available to the plant roots.

This soluble saline matter is chiefly composed of chlorides and
sulphates of lime and soda.

10 SOILS : THEIR NATURE AND MANAGEMENT
IV. — Classification

For the purposes of description and discussion, soils are classified
into many different kinds, and different authorities adopt different
methods. The simplest method, and the one naturally adopted by
practical farmers, is that first enunciated by Thaer, and we cannot
very well improve on it. It is founded on the comparative propor-
tions of the Proximate Constituents of a soil— sand, clay, humus,
lime, and gravel or stones — as whichever one of these predominates
it gives a distinctive character to the soil, and we thus speak of a
sandy, a clayey, a humous (or peaty), etc., kind of soil. Theoretically
we reckon that equal quantities of sand and clay produce a normal
" loam," but in practice anything over thirty per cent, of clay forms
a stiff soil and would be called " clayey." A clayey soil with a large
proportion of lime in it (i.e., over five per cent.) is called "marl," aud
marly deposits have in many cases in olden times been dug up and
spread on the surface of the fields to improve their fertility or
texture.

Hard-and-fast percentage of the proximate constituents, however,
cannot be given, because there must be endless variations of them,
but every soil can be included in one or other of the following seven
kinds : —

Sandy. Calcareous.

Loamy Gravelly.

Clayey. Humous.

Marly

While hard-and-fast percentages of the constituents of each class
of soil cannot be made, we can, however, indicate the limits of such
as follows :—

Sandy Over !)0 per cent. Sand

Sandy loam 80 to 90 per cent. Sand

Loamy 70 to 80 per cent. Sand

Clayey loam 30 to 50 per cent. Clay

Clayey Over 50 per cent. Clay

Marly 5 to 20 per cent. Lime

Calcareous Over 20 per cent. Lime

Humous Over 5 per cent. Organic matter

Gravel or stones may form part of any of the above, and give a
special character and name to them. In the same way humus
(which is present in all) may be in excess in any of the above varieties
and give it a corresponding character.

THE SOIL ITSELF 17

There may, of course, be any number of intermediate variations
of these seven classes or types, but at the same time every known
suil will be found to fall approximately within the limits of some
one or other of them or their intermediaries.

Y.— Distribution

The distribution of soils depends very largely on the geological
structure of any given country or region, and in several countries the
study of this distribution, and the production of soil maps, is a
branch of the Geological Survey. In our own country the issue of
" Drift Maps " showing surface deposits has recently been undertaken,
and as these are practically soil maps everyone interested in any
particular part of the country, more especially if he is looking for a
farm, would be wise to procure these sheets and use with the maps of
the "solid geology" of the district.

A study of these and similar maps will give one a very sound
knowledge of the soils of a region, their origin and composition
and characteristics, and show him what to expect before he goes to
see, or may save him the trouble of going to see at all, if he is able
to read a geological map. The colours and the signs on them indicate
that in one district we may find the older hard rocks with rugged
hills and scanty soil and exposed pastures, while in another we may
find a red marl of great richness for all kinds of crops, and well
sheltered, and in a third a stiff unworkable clay or a poor " hungry ;;
sand. The limestones, clays, sandstones, grits, etc., etc., known to
the geologist have each soils to correspond, but the study of these
is a very wide subject, and beyond the scope of this handbook.
Suffice it to say that such things as altitude, aspect, contour, water
supply, rainfall and local climate depend very much indeed on the
nature of the geological formations of any given district, as well as
does the nature of the soil itself.

In order to show how the geological formations influence the
distribution and nature of soils, the following short sketch is given
beginning with the oldest and working up to the newest deposits,
and indicating in general terms the prevailing chaiacter of the soil
we may expect to find on each.

1. — Primary Formatk >ns.

Granite. — Granite rocks generally occur as "bosses" or isolated
tract3 of the most rugged character. The felspar contained iu
them in decomposing gives rise to a clay which collects in the
c

18 SOILS : THEIR NATURE AND MANAGEMENT

hollows and is gritty from the silicious matter in the original rock.
As it is generally high lying and of no extent there is little cultivation
carried on, while the rocky part forms bare hills with scanty pasture,
only fit to carry sheep or cattle. Met with most largely at Aber-
deen, Dalbeattie, Dartmoor, and the Wicklow Mountains.

Trap. — A name given to several varieties of igneous rocks found
in various parts of the country. Being composed of many different
minerals they weather down into fairly fertile soils, though some-
times a little stiffish. The basaltic plateau of Antrim is a good
example, while they are also met with in Skye, Mull, Renfrew,
Edinburgh, and the Cheviot ranges. From these as centres,
quantities of the trap rocks have been carried during the Ice Age all
over the Lowlands of Scotland and the north of England, and have
helped considerably in the making of the soils of these regions, and
added to their fertility.

Archaean. — The oldest sedimentary rocks are the mica-slate and
gneiss of the north-west of Scotland and the Western Islands.
These places are of a particularly rugged and wild rocky character,
with little soil to speak of, and are wholly devoted to sheep and
cattle walks.

Cambrian. — This group is composed largely of slate rock and
flagstone, and is met with most largely in the ruggedest parts of
Wales, but is also found in the north of Scotland and south- west of
Ireland. Where limestone beds occur there are patches of good soil,
but usually it is thin and inferior and the districts are only fit for
sheep and cattle.

Silurian. — The greater part of the Scottish Highlands, the
southern districts of Scotland, part of Cumberland and Wales, th»
east, north and west of Ireland are all on the formations of this
group. The hilly parts are in sheep walks, but on the lower parts
are found good dark brown or red loamy or stony soils, often broken
up with rocky spots. Some of these soils are greatly deficient in
lime, which must be applied to make them productive, but they
make good loamy varieties when well farmed, as exemplified in
Galloway.

Old Red Sandstone. — This group of rocks gives rise to soils of the
most noted fertility not only in the British Islands, but similar
rocks yield good soils throughout the world. The shores of the
Moray Firth, East Lothian, Hereford, Devon, and Tipperary
are noted for their farming and splendid soils and crops. The
soils are for the most part sandy, loamy, or marly, according
to which beds predominate below them, and are always of

THE SOIL ITSELF 19

a rich dark red colour from the superabundance of iron oxide
present.

The red soil of Dunbar, which lets at £5 per acre per annum, and
grows the best potatoes in Britain, is on this group, while wheat
ripens in the north of Scotland on this soil when it will fail on the
adjacent Silurian and other primary rocks.

Mountain Limestone. — This forms the "backbone" of England —
the range of hills runuing from the Borders to Staffordshire — and
underlies the great central plain of Ireland, besides showing up in
small pieces and strips elsewhere.

It forms a thin soil of the lighter class, but yielding a naturally
sweet herbage on which sheep and cattle thrive, some of the best
sheep walks in England being on this formation : sheep's fescue
grass forming a large part of the pasturage. These districts are
often hilly or rocky and bare of soil, but they are noted for the
quality of the mutton produced.

Millstone Grit yields a light, gritty, free-working soil, but very
poor and hungry : one of the poorest sandy soils in Britain. It
usually, however, forms tracts of high-lying, heathy land in central
north England, and elsewhere round the edge of coal " basins," and
is mostly in sheep walks. Deficient in lime and clay.

Coal Measures. — These consist of alternate beds cf shale and
sandstone, and almost universally yield soils of inferior quality —
poor, thin, hungry sands or else yellowish clays, according to which-
ever beds predominate— and therefore are inferior districts to farm
in, though containing great mineral wealth. In the north of
England and in Scotland they are largely overlaid by the " drift,"
which, however, largely takes its character from the underlying
beds.

Magnesian Limestone. — This is a deposit composed partly of the
carbonate of magnesia in combination with the carbonate of lime,
and occurs as a long, narrow strip running up the central part of
the north of England. Magnesian limestone is not suitable for
farming purposes ; it yields a poor, thin, crumbly soil, carrying
poor pasture and requiring high farming to make it yield good
crops.

2.— Secondary Formations.

Jjfew Red Sandstone. — The red sandstones and marls of the
Permian and Trias are very similar in character to those of the Old
Bed Sandstune, and almost invariably yield good red loamy or
marly soils. The red soil of the Midlands is mostly on these
formations, on which are some of the finest pasture lands of

20 SOILS : THEIR NATURE AND MANAGEMENT

England and most noted cheese-making districts— especially where
the Keuper Marl conies to the surface.

Lias Clay forms a fairly rich clay soil weathering to a brown
colour. Much of it is in pasture and too stiff to cultivate, flat or
undulating. When drained it is the basis of some good dairy
districts, as in the vales of Gloucester, Evesham, and Berkeley ;
also in the dairy districts of Somerset, Gloucester, Warwick, and
Leicester.

Great Oolite. — The soils of the Bath or Great Oolite yield those
of a typical " brashy" nature, that is, full of angular pieces of the
original (limestone) rock. They are mostly of the lighter class, and,
of course, calcareous, and exceedingly suitable for sheep and barley.
Fertility is moderate, but they are easily cultivated. The Cots-
wolds, Cleveland, and part of the Midlands are on this formation,
while the beech tree is indigenous.

Oxford Clay.— One of the most extensive clay soils of England
is based on this, and when joined by the Kimmeridge clay it runs
from Dorset to Yorkshire, forming "The Clays." It is difficult and
expensive to work, mostly level, badly needs draining, and nearly
all down in grass. Where some of these clay soils have been
cultivated in bygone years the land has been left in very high
crooked ridges, and it must have been very difficult and expensive
to work.

Weald Clay. — This is another of the great clay formations of
the country, though mostly confined to Kent. It yields a fine
grained, yellowish, clay soil, very difficult to work, and very wet
until drained. It forms a very flat district, and much is still in oak-
forest land or natural pasture.

Gault Cla;/. — A strong, blue, tenacious clay soil, known in most
districts as "blackland" from its dark colour. It yields good
pasture, but requires much draining, liming, etc., to make into
arable land.

Greenland. — The Lower Greensand is the basis of many of the
unproductive sandy soils and barren heaths met with in some parts
of southern England.

The Upper Greensand is the basis of one of the finest of the
lighter sandy soils, especially when it mixes with the chalk marl.
It yields particularly good hop and fruit soil (as at Farnham in
Surrey).

Chalk. — The Lower Chalk deposit yields a thin, light soil, well
adapted for barley, roots, and sheep-folding, and is mostly in cultiva-
tion. . In some cases the soil is a clay formed as the residue from

THE. SOIL ITSELF 21

chalk which has been dissolved away. Chalk Marl and Greensand
make a good soil when mixed.

The Upper Chalk forms the "wolds" of Yorkshire and Lincoln,
and the " Downs " met with in the south of England, famous as
sheep walks ; thin soil with short sweet pasture, dry and unculti-
vated, and covered with loose Hints.

3.— Tertiary Formations.

London CI" ;/.— Another of the extensive clay deposits of the
south of England, forming the London and the Hampshire " basins."
It yields a tenacious brown or yellow soil, very expensive to work,
and much in pasture, but improved by liming. When well culti-
vated it yields good crops of corn, but requires liming and bare-
fallowing very extensively to develop it after draining.

Bagshot Sands. — Occur in patches over the London Clay as at
Bagshot and Aldershot. They yield a poor, hungry, sandy or
gravelly soil, mostly in heaths or copsewoods. Sometimes fairly
fertile when mixed with London Clay.

4.— Quaternary Formations.

Boulder Clay.— A deposit left from the action of ice during
the Great Ice Age. It covers large areas of the country, especially
in Scotland, and is really the "formation" of such districts, and
determines the nature of the soil. The Boulder Clay is a stiff
impervious clay ("till") full of stones and boulders which have been
derived from the rocks in the neighbourhood, and yielding a
clayey soil on the top. When well farmed it is often a good
cropping soil, and many of the soils of the Lowlands of Scotland
and the north of England rest on it. In the south of England
many of the good corn districts rest on the Great Chalky Boulder
Clay, as, for example, the " Boothings " of Essex.

The Glacial Drift is reckoned of more recent age and is of a
gravelly and sandy nature. Where it occurs in patches or large
areas it shows a much lighter soil than Boulder Clay. Many of the
gravel pits and sand pits in various parts of the country are
found in this, while of course the top soil partakes of the same
nature.

Brick Earth. — This only occurs in certain areas round the estuary
of the Thames ami on the neighbouring east coast. It may be described
as a calcareous loam of exceptional natural fertility and physical
texture. If the " red soil " of Dunbar (Old Bed Sandstone) be
classed as the most valuable for farming purposes of any in the

22 SOILS : THEIR NATURE AND MANAGEMENT

British Islands, then this may be put as the second best. Much
of it is devoted to seed growing and market gardening pur-
poses.-

5. — Recent Formations.

Teat. — The basis of part of the Fens (" Blacklands"), the Bog of
Allen, and many of the low-lying soils in hollows in the hills in
northern districts. It forms of course a typical humous soil, but is
usually not very fertile till limed, clayed, etc., after draining. It is
nearly all composed of the decayed or partly preserved bodies of
plants which grew on the spot— mosses, heaths, etc.— and may be
more or less mixed with earthy silt in parts.

Alluvium. — In a general way all the level flats along the sides of
rivers, estuaries, marshes, etc., are reckoned to be deposited by the
streams in flood time, and form alluvial material of various kinds.
The soil is usually loamy in nature, but it may range from sand and
gravel to clay, according to the nature of the deposits farther up the
stream. It is thus made up of a mixture of the washings from all
the other soils, and is usually the most fertile of any in its neigh-
bourhood. The drawback is that drainage is difficult because of its
levelness, while it is apt to suffer from flooding.

There is one rule with regard to the texture and composition of
alluvial soils that is of interest. The stony and gravelly varieties
are in the upper reaches of a stream, the sandy soils about the
middle of its course, while the estuarine deposit is usually the finest
silt or clay. Again, in going across a valley the stony part is next
the stream, the sandy in the middle of the level stretch, and the
clayey part nearest the high ground.

The above is only a very general sketch of this particular p.irt of
the subject, and details must be sought in works specially devoted
to agricultural geology. Almost every little formation has its own
specific soil or farming characteristics, and only a large scale
geological map can give true guidance as to the special surface
conditions at any spot. In this country the 1-inch maps of the
Geological Survey (solid and drift) should be procured for the
district in which a student or farmer is personally interested, and
much valuable information bearing on the farming will be gleaned
from them.

One more point is worthy of note in connection with this branch
of the subject, and that is, where two formations come together the
mixture is likely to make a better soil than either separately. If,
for instance, a clayey district lies alongside a sandy one, then there

THE SOIL ITSELF 29

is likely to be a strip of loamy soil between the two, which will be
more valuable than either. A marl also is better than either clay or
limestone by itself, and so on with as many cases almost as we can
find formations.

VI.— Fertility

Intimately connected with the composition of the soil, and indeed
forming a special subject of study, is its fertility. The great bulk
of most soils is composed of sand and clay with a little humus or
peaty (organic) matter in thern, but a soil that contains only these
things is certain to be barren, and we have many examples of such
throughout the world. The "proximate constituents" only form
the solid basis of the soil, as it were, and serve to hold and preserve
those chemical bodies which are required by plants to build up their
tissues. These chemical ingredients have already been mentioned,
and it is the presence of some of them in sufficient quautity and in
an available state which helps to make a soil fertile, and their
absence the converse. They must be present in a soluble state in
the film of water which surrounds the particles of soil, though the
roots of plants have themselves a certain amount of power to
dissolve out the ingredients desired from raw mineral matter. These
bodies exist in the soil as silicates, carbonates, phosphates, etc., and
when forming part of undisintegrated mineral fragments are quite
useless to plants. This explains why an analysis of a soil may show
it to contain plenty of fertility, and yet it may refuse to grow crops ;
it is only the small percentage readily available that is of value. It
has already been shown what a very small portion of a soil is
soluble in water or in a weak acid, yet it is this soluble part only,
and its composition, which concerns us in the question of fertility
from this point of view.

Out of say seven of those chemical substances required by plants
the majority are present in superabundance for growing many crops,
and only three— nitrogen, phosphoric acid, and potash — are likely to
become deficient. Accordingly we apply manures to replace or
increase the supply of these, and therefore nearly all our elaborate
applications of natural and artificial manures resolve themselves into
applying various home-made or commercial combinations of these in
the form of dung, compost, nitrates, phosphates, etc.. as will be.
detailed later on.

Fertility of the soil is, however, a state of matters due to many

24 SOILS: THEIK NATURE AND MANAGEMENT

different factors. It is not altogether a chemical question, for the
amount of the particular chemical bodies in the soil is only one
item out of many bearing on the question. The physical conditions
or properties of the soil as regards texture, moisture, etc. (as will
be explained in the next chapter), are of the foremost importance.
Conversely, a soil may be fertile as far as its composition is con-
cerned, but from excessive dryness or excessive wetness, from close-
ness of texture, etc., it may refuse to grow crops.

The amount of soluble and undissolved plant food naturally in
a soil is what is termed the ''inherent fertility" of it, and a farmer
pays rent for liberty to remove it in small annual portions in the
crops and stock he sells off his farm. By adding manures he
replenishes this store, and if he manures highly, he increases the
stock of fertility and adds to the " cumulative fertility " of the soil
and puts it into good " condition."

It is not possible, however, to make a bad soil into a good one ;
to prove this statement we need only take the case of one
important constituent — phosphoric acid. In an ordinary fertile soil
there may be two per cent, of it present : this means, however, that
in the first nine inches there will be thirty-six cwt. of this ingredient
present, equivalent to, say, from five to seven tons of a phosphatic
manure like superphosphate or basic slag. Now when we reflect that
three cwt. to five cwt. of such manures are a common dressing per
acre in practical farming, it can easily be seen how impossible it
would be to make up a soil, if it happened to be naturally deficient,
to the proportions of constituents such as we meet with in ordinary
cases.

The development, or realisation of the fertility in a soil, again,
depends very much on the farmer's management of it : on the
proper cultivation, seeding, etc. ; on catching the land at the proper
"tide," as it were, to do certain jobs ; on the weather, and so on ; all
of which will be better understood after a perusal of the pages to
follow.

The inherent capabilities of the soil can very well be judged by
certain "indications" of fertility and barrenness that can quite easily
be seen by anyone looking over a farm. Thus, good land will
consist of gentle slopes and flats ; grow strong healthy trees,
excepting beech and pines ; have good hedges ; show rich green
permanent pasture with plenty of white clover ; have clover
growing in the railway cuttings ; have a deep soil, reddish or dark
brown in colour ; and show strong, healthy weeds — such as ragwort,
thistles, bracken, etc. On the other hand, bad land will be indicated

THE SOIL ITSELF 25

by beech and pines being the prevailing trees; stunted trees and
hedges ; sedges, daisies, and oxeyes growing plentifully ; quaking
grass, Yorkshire fog, and barren brome being common in the pastures ;
soil being thin and wet or spongy underfoot ; thin wiry couch and
bent grasses being common on the arable land; and heath and moss
growing plentifully.

A good crop or a bad crop may sometimes be the accident of a
particular year : good land badly farmed or in a drought will show
an inferior result, while poor land well farmed or in a genial season
may yield a good crop for once, but the natural indications, in the
shape of the trees, hedges, weeds, etc., etc., will always show the true
nature of the land.

CHAPTER II.-THE PHYSICS OF THE SOIL

Having now got an idea of what the soil is, and how it came to be
what it is, we may proceed to examine the physical characteristics
and conditions which it has in common with all other bodies on
the face of the earth. The soil is made up of particles of various
kinds of materials, and these are subject to the ordinary laws of the
physical universe in common with other forms of matter, and
how these influence its farming will next engage our attention. It
is best to take each branch of the subject by itself as follows :—

I.— Size of Particles

In connection with the study of the visible constituents of the
soil, the size of the particles must be considered, for the texture,
tenacity, and many other characteristics depend very much on this
feature. Further, the predominating size of the particles has much
to do with the nature and quality of the crops grown. This subject
has been taken up of late years by American investigators, and
some interesting facts have been elucidated. An ordinary clay soil is
estimated to contain 400,000,000,000 particles per ounce, while a
"good corn soil" has about 280,000,000,000 particles in the earthy
part, and those experiments show that fertility and also suitability
for various crops is very largely a question of fineness of particles.
Thus with their refinement of " soil surveys " and methods, investi-
gators state that soils with 2130,000,000,000 to 350,000,000,000
particles per ounce are adapted for potatoes; 350,000,000,000 to
450,000,000,000 for onions, and so on. In analytical tests of soils it
is customary to pass the same through a two-millimetre sieve, so as
to separate the fine " earth " from the coarse stones, sand, or
particles, and then to confine attention to the former. It is inter-
esting to know the proportion this fine earth bears to the total in
the different classes of soil, and below are given some typical
examples in percentages by weight : —

Clayey 97

Clay Alluvium 92

Loamy 80-70

lied Sandy Loam 50-40

Sandy 30-20

'26

THE PHYSICS OF THE SOIL

27

It is, of course, only the clayey part that is likely to be found of
the smallest size, for the grit and stones are uf more measurable
dimensions. In a sandy soil half of its bulk may consist of particles
over , ,yll(T of an inch in diameter, but on the other hand, when sand
is extremely fine (as "quartz flour") it approaches clay in its
physical characteristics, and may actually be " cold and wet," and
even plastic, where it predominates in the soil. (See Fig. 3.)

Fig. 3. — Microscopic Section <>f Arable Clay-loam Sou,.
BHOWiNfi Particles.

In a general way, the finer the particles of a soil are the more
fertile it is. This is simply because there is more surface exposed to
the action of the roots than where the grains are larger, for it is in
the film of water surrounding each particle that the root fibrils feed,
and consequently the roots more readily get at the chemical
compounds which are either in the particles or in solution in the
water film. On the other hand, the liner the particles the more
dense and solid is the soil as a whole, and the more in need of

25 SOILS : THEIR NATURE AND MANAGEMENT

cultivation and other treatment to open it up so that the roots
can ramify more easily.

If the particles of a soil were all spherical and of the same size
— like a boxful of marbles— the spaces between would amount to

26 per cent, of the whole bulk. If the particles were of irregular
shape and size they would occupy a greater or lesser proportion of
the space according to their shape and size. In an average soil the
air-space occupies about 40 per cent, of its bulk, but as the particles
themselves are more or less porous to water it is possible for the
space occupied by water— when saturation is complete — to reach
50 per cent, of the whole, though other soils may only mount to
30 per cent.

II. Porosity

Vrom the fact that the soil is composed of particles we naturally
conclude that there are spaces between those particles, which we
term pores, and just as the size of those particles influences the
farming of the soil, so, conversely, does the size of the spaces between.
In common language we talk of soils being porous or dense ; a sandy
or gravelly soil is an example of the first and a clay of the latter state.
It is necessary to explain that " porosity," as used with reference to
a soil, is not the sum of the spaces between the particles in, say, a
cubic foot of soil, but the relative sizes of the spaces in different
soils. For instance, clay has probably a pore space of 50 per cent,
(measured by the amount of water it will hold), while a coarse sand
may only have 23 to 30 per cent., yet we call the sand the more
porous soil because it will allow of the freer passage of water
through it. Conversely, a dense sod is one that does not allow
water to pass easily— like clay.

The variation in the pore space of soils is shown in the following
table : —

Area in

Pore Space

sq. ft. of

per cent.

surface in
u cub. ft.

Fine Clay

52-9

173-7

Clay Soil

48-0

110-5

Loamy Clay

49-2

70-5

Loam

44-1

46-5

Sandy Loam

38-8

36-5

Sand

32-5

11-0

THE PHYSICS OF THE SOIL 29

From the table it will be seen that in a strictly " physical "
sense the clay has the greatest pore space, yet we say the sand is
the most porous, because the individual spaces are larger and
allow water to descend more readily.

III. -Texture

The texture of a soil is intimately connected with the pro-
port ion of Proximate Constituents present : an open texture is
due to a large proportion of sand or gravel or lime, and carries
with it little tenacity but much ease of cultivation, while one
of close texture, due to a superabundance of clay in its com-
position, is accompanied with much tenacity, difficult tillage and
slow percolation of water.

if more than the half of the soil is composed of clay then
the texture will be decidedly tough : liable to set hard in dry
weather and to crack by shrinkage into cubical masses, while
in cultivation it will always tend to become cloddy or lumpy.
Even if there is more than one-third part of it clay it will
have a texture on the stiffish side. A moderate admixture of
all the ingredients is best, and a large proportion of organic
matter will improve the texture as well as anything else, and
in this way a dressing of farmyard manure improves matters
apart from its manurial effects, whether the texture is too close
from the presence of a large proportion of clay, or too loose
from much sand. Liming, again, has the effect of curdling or
flocculating the colloid ingredient of a clay soil, and thus tends
to make the same crumbly and friable and more easily cultivated.

Again, marling, though now seldom carried out on account
of tlie expense, was an old method whereby light sandy soils,
and even clayey ones, had their physical characteristics largely
improved. Another method of improving the texture is to grow
a forage crop like rape, mustard, clover, etc., and plough it in :
this "green manure" will become humus in time and do much
good. Where land is worked on a rotation with a grass crop
grown at intervals, the ploughing down of this "lea" is also
very helpful in the same way.

For temporary improvement of the texture of the soil in the
way of making a tilth, however, nothing is equal to the action
of frost. Whether, as some say, the frost acts on the colloid
clay and congeals or flocculates it, or (what is more likely) the
particles of soil are simply split apart by the expansion of the

30 SOILS : THEIR NATl'RE AND MANAGEMENT

frozen moisture between them, nothing else so improves the
texture and aids the work of cultivation in making a good
seed bed. This is one of the reasons why early ploughing in
winter is practised as much as possible, so that the soil is
turned up to the full action of the frost, and then when the dry
weather of spring comes it is found to be in a loose, friable
condition.

Besides the power of farmyard manure and lime in altering and
improving the texture of a soil, the ordinary chemical artificial
manures have also a certain effect. Thus, such manures as sulphate
of ammonia, chloride of potassium, common salt, etc., have a curd-
ling or flocculating action on the soil particles, similar to that
of lime, and so make the texture freer. On the other hand,
nitrate of soda has a tendency to destroy flocculation, and thus in
the case of clay makes the soil stickier than before. These effects
are quite separate and apart from the chemical reactions in a soil as
the result of manuring.

IV.— Tenacity

The tenacity of a soil — Le., its stickiness- -varies very greatly
according to its texture and component parts. It is, of course, most
pronounced in the case of clay and least with sand or gravel or peat,
and on the degree of this depends much of the tillable ease or diffi-
culty of cultivation. Clay is silicate of alumina, a portion of which
is in a colloid or gluey state — to the extent of about l'o per cent, in
an ordinary clay soil — and it is to this portion chiefly that the
adhesive nature of the soil is due. Clay soils are thus tenacious,
and resist the passage of the plough or implements of cultivation
through them, and therefore they are mostly laid away in perma-
nent pasture ; they have either never been ploughed up for arable
work, or they have been laid down in grass during the last twenty
to thirty years, since the era of cheap corn set in, and the value of
crops in general became reduced.

The difference in the tenacity of soils may be so great that
one soil may require five times more force to pull a plough
set at a given depth through it than is necessary in other cases,
though the effect of tillage and cultivation generally is to reduce the
tenacity.

When farmers talk of light and heavy soils they do not refer to
the actual weight at all, but to the proportionate force required to

THE PHYSICS OF THE SOIL 31

move the implements of tillage through the soil. Thus a sandy soil
is called '' light :' because it is easily cultivated, and a clay soil is
" heavy " because the draught to the work-horses is heavy ; in other
words, it is the tenacity that is light or heavy according to the
inherent texture of the soil. Thus light soils may be classed as
l> two-horse " lands and heavy soils as " three-horse " lands, according
to the number of horses needed to pull a plough at work.

A certain amount of tenacity is necessary, because if there is none
at all, from the want of a little clay (or humus), then the particles of
soil will drift with the wind, and will not be capable of giving
the plants roothold.

The coherence of a sandy soil is greatest when it is wet ; it will
stick slightly together when damp and fall to pieces when dry. In
the case of a clay the reverse holds ; it coheres least when wet, but
when dry sets into a hard lump.

It is a rule not to cultivate clayey soils, if it can be avoided, when
too wet, because their plastic nature causes them to " puddle " and
thus the possible tilth is destroyed.

Y.— Retentiveness

Improving the texture of a soil by liming it is equivalent to re-
ducing its tenacity, and making it more workable, but on the other
hand we must not forget that it is partly by its tenacity that the
power of retentiveness for plant food is controlled. An open sandy
soil lets the water through easily, but it also lets the elements of
plant food escape as easily ; a clay holds water, but it will also hold
its fertility, and any manures put on will be retained. In practical
farm work this means that autumn manuring cannot be practised
on light arable soils, because before spring time the rains of winter
have washed all the goodness out of these manures down to the
drains or deeper layers ; on a heavy soil, on the contrary, the material
is retained, and putting on farmyard dung, compost, and even some
classes of artificial manures, in autumn is the most desirable
practice.

We can thus see that a loamy soil of medium texture and
tenacity is the most desirable for mixed husbandly, on account of its
medium power of retentiveness.

The retentiveness of a soil for -\\ater depends directly on its
capillarity, which in turn depends on the proportion of clay or
humus present. The measure of this is very well shown in the

32 SOILS: THEIR NATURE AND MANAGEMENT

following table, which indicates the percentage volume of water
held by the different classes of soil : —

Sandy Loam 17

Loam 26

Clay Loam 28

Clay 34

These figures also exhibit very clearly comparative characteristics
of various kinds, as regards the power required for plough draught,
the friability of the soils, their capillarity, as well as their retent-
iveness for manures. Peaty or humous soil is exceptional ; its
corresponding percentage would be very high, but while very
retentive of water or manurial matter it would not be tenacious.

The retention of manure or plant food in the soil is due partly to
physical and partly to chemical action. Physically the soil acts as a
filter : if some liquid manure is poured on to a quantity of earth
the water that drains away below will be clear and comparatively
pure, thus, exemplifying the principle of sewage irrigation. The
solid parts are kept back partly by the sieving action of the soil and
partly by the attraction of cohesion on the surface of the soil
particles, so that even the soluble salts are held mechanically in
this way. For these latter, however, the retentiveness is mostly
chemical, that is, some chemical reaction takes place in the soil
whereby soluble salts are recombinei into some compound that is
less soluble. It is believed, for instance, that there are many
double silicates in the soil— known as zeolites— of which the basis
is silicate of alumina, but combined with some compound of lime,
potash, soda, or ammonia, and that when any manurial body is put
into the soil there is an immediate chemical union of its constituents
with the silicates of the soil. These compounds are easily decompos-
able iu the ordinary carbonic acid water of the soil, and the acid
reaction of living roots is also sufficient to decompose them, so that
there is a constant chemical action and reaction going on.

Again, the humic acid of the soil will readily unite with such
bases as lime and magnesia, thus retaining them in the soil. A
soluble (monobasic) phosphatic manure assumes the insoluble
(tribasic) form immediately it comes into contact with lime, or iron,
or alumina in the soil, and so is held in its turn till Avanted by
the roots of plants.

Every soil, therefore, that has a sufficient amount of clay or
humus in its composition will hold— either physically or chemically
—the ingredients of plant food until required by the crops. A

THE PHYSICS OF THE SOIL :«

sandy soil is poor because it lacks the retentive components, and lias
thus allowed its ''goodness" to be washed away, while even on fairly
retentive soils a small portion of the soluble salts (especially nitrates)
are continually being lost in the drains.

The retentive power of any soil is very much helped by the
presence of a growing crop on it. A grass field will hold all the
manure put on to it by the action of the living root fibrils, iu both
summer and winter. On arable fields, however, that are devoid of
crops in winter, there is a great loss of fertility from the excessive
downward wash of the rain where there are no living roots to
keep hold of it. For this reason good practical farmers grow as
many autumn-sown crops as possible (''winter" wheat, oats, barley,
or beans), and some even sow "catch-crops" of clover, rape,
mustard, etc., simply to occupy the ground to prevent waste of
fertility, and to form a manure when eaten off by sheep or ploughed
down, until the time comes round for the next regular crop to
be planted.

VI. -Depth

The depth of the ordinary soil remains remarkably equal, or
within certain limits, all over the world. It usually runs from three
inches to over a foot, while by far the commonest depth is six
to eight inches, or, in the language of the farm, it is " plough-deep,"
as an ordinary furrow-slice turned up with a two-horse plough
usually runs from five to seven inches deep, according to the texture
of the soil— extra work with three or four horses going, up to twelve
inches or so if the depth and texture permits. This of course refers
to the soil proper, for, as elsewhere explained, the subsoil must
not be ploughed up on account of its poisonous qualities, though
it may be greatly improved by stirring it to let the air enter.

This regularity in the depth of soils is wonderful : in France it
runs from four to thirteen inches deep, in Germany a little less,
the black loam of Russia is thin, the soils of New England are
about six inches deep, the western prairies a little deeper (some-
times down to eighteen inches), in Australia from four inches to a
foot, and in New Zealand four to nine inches. Some exceptional
soil?, as alluvium, for instance, may be much deeper than the above,
but as a rule the great majority come within these limits.

Of course the difference between four and twelve inches makes
a vast difference in the value of soils and in the methods of
farming them. If a shallow soil is very fertile, then cropping may

D

:U SOILS: THEIR NATURE AND MANAGEMENT

be carried on successfully, but in ordinary practical farming a
moderately deep soil, even if only of medium fertility, is more to be
desired. One reason for this is the fact that the roots of tbe crops
only ramify freely in the soil proper, and do not readily enter the
subsoil, especially if the latter contains any raw unoxidised material.
This means that in a deep soil the crop is more independent of
surface conditions and is less likely to suffer from drought than on
a shallow soil, while it has a greater storehouse of fertility from
which to draw.

Where a soil is shallow or has not been cultivated very deeply,
it may be advisable to try to improve it in this respect. Actual
ploughing to a greater depth must be done very cautiously,
however, for fear of bringing too much of the poisonous subsoil
to the top, as where this is done the field may be injured for
several years, until, in fact, the raw stuff has become meliorated into
good soil.

As a rule a thin shallow soil is poorer in plant food than a deep
one, because the working of the natural forces which has prevented
the formation of a deep soil on a given spot, and has prevented the
accumulation of plant food in it ; conversely, a deep soil is a betfer
one.

VII. -Weight

Study of the weight of a soil brings out some surprising figures,
which give us quite different ideas on various points to those we
naturally expect. The actual weight of a cubic foot varies very
considerably according to the composition of the soil, and whether
it is stirred up by cultivation or pressed down tight and hsrd.
The actual weights of certain selected varieties (air dried) are shown
in the following table : —

Soils.

Peaty
Clayey-
Loamy
Sandy

Weight of

>l«r^lir

v.vhk foot.

Gravity.

■lbs.

49

•78

G6

1-06

76

1-22

SO

1-28

•

As a matter of trial pure peat may weigh as little as 30 lb., while
sand may run over 100 lb. per cubic foot in the dry state, with all

THE PHYSICS OF THE SOIL 35

sorts of intermediate varieties between, and it will thus be better
understood that a clay soil is really lighter than a sandy one per
cubic foot, but is called "heavy"' because of its tenacity or difficulty
in working. A medium ordinary arable soil in good tilth is taken
at 7"> lb. as a sort of standard. At this figure it will be seen that in
the first nine inches of soil there are over 2,000,000 lb. of material, or
to every inch in depth there is about 120 tons per acre. These
figures are enormous, and show us how small an affair a top-dressing
of compost or dung is compared with the bulk or weight of work-
able soil. If we reckon that an ordinary soil contains one-tenth
per cent, of nitrogen in its composition, it yet represents at least
2,000 lb. per acre in the top soil. We thus see that when we apply
a manure, which perhaps only contains 50 lb. of nitrogen per acre,
it really is the merest trifle compared with the reserve stores of the
soil, though it may stimulate a crop. Similar figures apply to other
ingredients, and a dressing of manure at the rate of say five cwt. per
acre is a small matter compared with the 1,000 tons of soil to which
it is applied ; the explanation of the effect is that the elements of
the manure are more or less soluble and immediately available to
the crops, while those in the soil are not.

Intimately connected with the weight of a soil is its specific
gravity, i.e., the weight compared with an equal bulk of water. In
a loose, open body, full of pores and spaces like the soil, there are two
kinds of specific gravity, that of the body as a whloe — pores and all
— and that of the materials of which it is composed. The figure
that is taken, however, is that of the soil as it is, and not of the
complex components of it. In the preceding table it will be seen how
this varies according to the comparative weight of a cubic foot in its
ordinary state, averaging about 1-2. On the other hand, if the
materials were taken as solid bodies, then the average specific
gravity is about 2-5, or about the same as that of the actual rock-
forming minerals. To distinguish between the two it is usual to
terra the first figure the "apparent" and the latter the "true"
specific gravity, but it is the former which is the one to be reckoned
with in ordinary spade or plough work.

From these figures we can see what an enormous weight of
soil we are dealing with. In ploughing a field, for instance, say only
five inches deep, we are moving GOO tons of soil per acre ; in
levelling down a bank or cutting a drain or ditch, we may be
handling as many tons ; while a dres.->ing of lime or earth, or any
bulky manure, though involving much labour, is small iR proportion
to the bulk of the ordinary soil.

36 SOILS : THEIR NATURE AND MANAGEMENT
VIII.— Colour

If half-a-dozen samples of different soils are put together side by
side, it will be seen that they vary very much in colour. Those
soils which are extremely rich in humus, or organic matter, such as
peaty and alluvial soils, will he more or less dark, perhaps actually
black. Those overlying a chalk formation, where the chalk mixes
with the top soil, will be whitish, or at least greyish. Those over-
lying the red sandstone formations are of a reddish or chocolate colour,
and so on with a whole host of other variations. As a matter of
fact, the colour of a soil is primarily due to the colouring matter in
the rock material from which it was originally made— altered
probably by oxidation, etc. — and it is often possible to follow the
arrangement of the underlying formations by simply noting the
changes of colour in the surface soils.

The principal colouring matters in a soil are humus and oxides
of iron ; if both of these were absent the soil would be white, as is
the case with pipeclay and chalk. The carbonaceous matter has, of
course, grown in the soil, but the iron compounds must have been in
the original minerals from which the soils have been derived. In
these minerals the colouring matter usually exists in some protoxide
compound — yielding a light or yellow colour which it gives to the
soil ; as it becomes oxidised into the peroxide form it changes from
red to brown, and a reddish-brown is the final colour of such soils.
The process may have taken as long as the formation of the soil
itself, but sometimes we can see it happening before our eyes.
When a furrow-slice is freshly turned up by the plough it is often
lightish brown in colour, but after a few days it has become a
darker brown— the protoxide has become oxidised into the peroxide
of iron.

In the case of raw clay of a bluish colour it is often sulphide
of iron (FeS2) that is present, a salt often found in the subsoil,
and poisonous to plants till it becomes oxidised into the sulphate.

As will be shown immediately, the colour of a soil immensely
influences its usefulness in growing a crop on account of its effect
on the temperature, and farmers always prefer one of the red or
dark type.

The most desirable colour is black, and the least desirable is
white, the others are intermediate. The reason for this is that
black absorbs the heat of the sun most freely,, while white is at
the other end of the scale. As heat is one of the principal factors
in making plants grow, it follows that, other things being equal,

THE PHYSICS OF THE SOIL 37

the earliest and best crops will grow on the dark soils, and grey
or white will yield late and stunted crops, a conclusion justified
in actual farming. In this country peat and alluvium are often
not well drained, and therefore excess of water may counteract tht
advantage of colour, but the growth of wheat on the prairies
exemplifies what a black soil can do when other things are right.
Colour is not a thing that can be easily altered in a soil, but
heavy dressings of soot, of peat, or of swamp mud help to darken
it a little, while the continuous application of farmyard manure
also aids not a little, apart from its manurial value.

IX.- ©dour

The smell of the freshly turned-up earth is well known to
every worker in the fields as one of its physical characteristics,
and a few words must be devoted to it. This smell is not always
the same with every kind of soil, but varies very much according
to its source. If, for instance, some marshy soil be turned over
the smell will be largely due to decaying vegetation, and where
grass or other crop is growing the cdour may be partly due to the
crop. Apart from such cause, however, the ordinary earth has an
odour of its own, and according to some authorities a volatile organic
substance can be distilled off into water at a temperature of 140° Fah.
The chemical nature of this body has not been ascertained, but it
is believed to belong to the aromatic or benzene series.

The smell of a freshly turned-up furrow is reckoned one of the
delightful sensations of the country, and it is not surprising to find
that it is really due to the existence of a separable body in the
soil.

X.— Ventilation

It may sound rather strange to the uninitiated to hear that the soil
needs ventilation, but it does, and a soil that has not a sufficient
supply of air is not likely to be fertile, or at best will grow
stunted crops. The reason of this is that many of the chemical
and bacterial processes, or changes, which take place in the soil
resolve themselves into a case of oxidation, and therefore free
access of the atmosphere (containing oxygen) is necessary to promote
these changes.

Thus the action of the nitrifying bacteria, the oxidation of the
iron in the mineral material, the conversion of plant tissue into

38 SOILS : THEIR NATURE AND MANAGEMENT

humus and many other changes, all require the presence of air, and
these processes are expedited when the soil is broken up to admit it
freely. The processes of cultivation, such as ploughing, grubbing,
horse- hoeing, harrowing, etc., are largely carried out for the purpose
of breaking up the soil to let the air in, and a soil in a good state of
"tilth " is one that is in a well-ventilated state.

The great enemy of ventilation is stagnant water; a waterlogged
soil is one with the pores full of water, so that the air has no access,
and one of the objects of draining the land is that by the removal
of superfluous water the air is allowed to enter into the pores
between the particles.

So much does draining the land with pipe-tiles help the
ventilation of the soil, that cases have occurred where the crops were
immensely benefited by the work although no water ever flowed out
of the drains. The soil was naturally dry, that is, it permitted the
rainwater to percolate easily downwards below drain depth, but the
introduction of parallel rows of pipes into the soil allowed the air
access to the lower layers with decided benefit.

The air in the soil is not just the same as ordinary atmospheric
air, but, amongst other things, contains a very much larger pro-
portion of carbonic acid gas— between 3 per cent, and 15 per cent, or
over. Its presence is due to the decay of the organic matter in the
soil which gives off this gas, and the soil moisture absorbing it, gains
much more solvent power for carbonate of lime and other minerals
present.

While the removal of water by draining expedites the entrance of
the air, this very air hinders for a time the free entrance of the rain
from the top. Thus when a shower falls it tends to paste up the
pores of the soil, preventing the egress of the air, and a thunder-
storm may run off the surface because it cannot penetrate till the air
has gradually escaped. After such a storm (succeeding dry weather)
the soil will be heard to actually "sizzle" from the action of the
escaping air.

In a state of nature, the soil ventilation is largely carried on by
worms making burrows into the lower layers ; by roots forcing their
way through the material, dying and decaying, and so leaving a
channel ; and by various other methods. On the other hand, the
natural plants— grass, bushes, trees — have developed themselves to
suit a partially ventilated soil, but cultivated crops must have the
ground stirred so that the roots may literally have air to breathe,
because they have been artificially developed by cultivation. When
a piece of soil becomes covered with water, or even waterlogged, the

THE PHYSICS OF THE SOIL 39

land plants on it actually die by drowning, and their place will be
taken by aquatic varieties,

XI.— Moisture

A dry soil is a barren one ; no matter how much fertility there
may be in it, or how good its physical condition, it will refuse to
grow crops or anything else until there is some moisture present.
Much of the barren lands and " bad lands " of the Western States of
America owe their barrenness to want of moisture, and when water
is brought in by irrigation channels large crops of every kind can be
grown.

On the other hand, however, a wet soil — that is one with the
pores or spaces too full of water— is just as bad, because it is (1)
cold, (2) without sufficient air for ventilation and oxidation, and (3)
liable to become sour from the development of the acids known as
humic, ulmic, geic, etc. Absolute waterloggedness — i.e., every space
and pore filled with water— only occurs at well-depth, that is if a
hole is sunk in the ground until the water level is reached the top of
the water as it naturally stands in this hole is the well-depth or
" water-table," below which level the ground at that spot is
thoroughly full of water, and above which the water is held by the
capillarity of the particles of soil in decreasing percentages until the
surface is reached, where, however, it may be absolutely dry.

Water in soils is of course derived in the first place from the
rain, and for the less rainy parts of the British Islands it is reckoned
that of the total rainfall only one-third to one-half sinks into the
soil by percolation.

1. Percolation. — This depends very much on the texture of the
soil ; thus the rate differs very much in various soils. Through fine
clay the water passes very slowly, while through gravel it will run
quickly, and indeed the rate depends very much on the propor-
tionate size of the particles of soil. Perhaps the extremes are clay
and fissured chalk : water will pass through the chalk crevices six
hundred times faster than through clay, while if the clay has been
" puddled " the water will not pass through it at all. This failure of
water to percolate is one of the reasons why "poaching" of land by
treading it with live stock when wet, or ploughing or cultivating it
in that state, spoils it temporarily for cropping purposes — the water
cannot get down through it and the air is thus kept out.

The rainwater does not percolate downwards directly, but may
go sideways, or zigzag as it were, following the most open channels.

40 SOILS : THETR NATURE AND MANAGEMENT

It fills up the ground to complete saturation from below upwards,
and keeps on gathering until an outlet is found somewhere, for
instance, at a spring, or in a drain, or until it rises to the surface to
form a swamp. (See Fig. 4.) As already mentioned, the surface of
the " water of saturation " in the soil is known as the water-table, and
is approximately the level at which the water would stand in a well.
As ordinary drains are not usually put more than about three feet
deep, they seldom reach the saturated area, and therefore must per-
form their useful work in quite another way.

SWAM

Fig. 4. — Position of the Water-table in a Hill, and the Occurrence
of Springs (S and S').

It is manifest that anything that "opens up" a close texture
soil (such as clay) will promote the percolation of the excess of
water, and therefore cultivation is the first process in this line-
ploughing, grubbing, and similar work. Next comes subsoiling, and
where it can be possibly carried out it is a good thing to do. The
application .of liberal doses of dung, apart from its manurial value,
has the mechanical effect of improving the porosity and percolative
power. On the other hand, when the soil is too open (as a gravel)
an application of clung reduces this disadvantage, as does a dressing
of earth or clay.

Liming, again, on a clay soil, by its curdling or flocculating
effect, improves the percolative power.

2. Capillarity.— But water not only sinks in soils by percola-
tion, it also rises by Capillarity. This action is best exhibited by
taking glass tubes filled with different kinds of soil and immersing the
lower ends in a vessel of water. It will be seen that after a lapse
of time the water has risen — say in clay at one end of the series —
to a height of fifty inches, while in coarse sand at the other end it
will only rise to twenty-two inches ; with other soils the rise is
intermediate. Capillarity is indeed the exact opposite of perco-
lation, and the finer the particles of soil are the higher the water
rises. These tw conditions combine in a clay soil to make it

THE PHYSIC'S OF THE SOIL 41

" wet." The water soaks downwards with difficulty, while the
upward soakage by capillarity is greatest.

The particles of soil are coated with a film of water and it is
this film that has a constant tendency to spread, like oil on the
surface of a pond, from its "surface tension," as it is termed,
[t is in this film that all the soluble salts of the soil are found and
in which the roots of plants ramify, and when this dries up near the
surface, as in a drought, all the processes cease. As capillarity is
strongest in a clay soil, the crops suffer least on such in a drought,
for moisture comes up from the store below. On the other hand,
a clay suffers most in a wet season because of the excess of moisture.

This is the scientific explanation why in practice clays can be
cultivated successfully in dry eastern England while they are heart-
breaking soils to handle in wet districts.

It may be pertinently asked how it is that a drain removes
superfluous water if it does not tap the saturated portion of the
soil. The explanation is that the amount of water held by capillarity
varies according to the depth. If drain depths be taken downwards
and the moisture determined in percentages for each six inches, they
will be found to vary in a rising (or descending) scale. Thus —

the first

G inches

will hold .

16 per cent.,

the second

6 >.

>i ■

19 per cent.,

the third

6 „

»

22 per cent.,

the fourth

6 „

•>

28 per cent.,

the fifth

6 „

>)

40 per cent.,

the sixth

r>

„

56 per cent-

The placing of a

drain at this depth

immediately relieves the

**■•»».«. l6__ — — """"""

^-^ 28 _--'

z~- — _

c<=> r- — ■

^T *- ------ -- "^

56

Fig. .5. — Variation in the Percentages of Capillary "Water in the
Soil between two Pipe-tile Drains.

tension, as it were, and the excess of capillary water is removed, and
the remainder held in a proportion similar to that at the surface. In
the space between the drains the capillarity acts as strongly as ever,
and thus the sod remains damp, (gee Fig. 5.) Where the drains are
too far apart it is sometimes necessary to put in intermediate ones so
as to reduce the capillary water between.

42 SOILS : THEIR NATURE AND MANAGEMENT

3. Evaporation. — When rain is not falling to increase the surface
moisture, then evaporation comes into action and the moisture
gradually goes off into vapour in the air. The supply is kept up by
capillary action, and thus the current of water is kept moving. In
this way the salts in the soil are brought into contact with the roots.
Excess of this process, however, causes an efflorescence or layer of
white salt on the surface, and the "alkali lands" of America
are produced in this way. In this country the danger is met by the
downward washing of the rainwater from time to time.

As a matter of fact the occurrence of the soil salts, or soluble
part of the soil, is largely dependent upon the existence and
movement of the soil water. By the upward action of capillarity they
are carried to the roots of the plants or accumulated on the surface
when there is a drought ; by the downward percolation of the rain-
water they are washed downwards again, and in our wet climate very
large quantities are washed into the drains and lost, while loose porous
soils may actually become " leached " and nearly barren in this way.
There is thus a constant movement of the soil water downwards,
upwards, or sideways, depending altogether on the vagaries of our
climate, and varying with every shower of rain or spell of fine
weather.

The amount of water evaporated in a year is very great. It
depends, of course, very much on the average temperature of the
atmosphere of a district and on the rainfall as well ; in the south
of England more than half of the rainfall returns to the air from the
soil in this way, while from the surface, of ponds and lakes far more
is dissipated. In the neighbourhood of London over 20 inches of
water is evaporated from a water surface, varying from 3'4 inches in
July to '5 inches in December.

While evaporation of the soil water is retarded by a loose
layer of soil on the top, the moisture actually in the top parts is
quickly dissipated by piling it up into lumps or ridges. Thus in dry
districts high ridges or " balks " for root crops are a mistake —
they soon dry through and through— but are suitable enough in
dampdistricts ; while the "flat" system has to be adopted — whereby
everything is on the level — where the summer rainfall is deficient.

XII.— Temperature

We are all accustomed to the fact that the temperature of the
atmosphere, as measured by a thermometer, varies from day to day
and from hour to hour, but it is also a fact that we have similar varia-

THE PHYSICS OF THE SOIL 13

tions in the temperature of the soil itself, and of the air or gases
in it. It is on the condition and variations of these that much
of the success or failure of plant life depends. All our farm
plants, and the bacteria which serve them, thrive best at temper-
atures between say 60° and 90° Fall., and anything above or below
these figures has a tendency to check the growth of them.

The variations in the temperatures of a given soil and the
different temperatures of distinct soils are largely due to the
differences in the materials and colours met with. Thus a sandy,
gravelly, or stony soil is always more or less "hot," and a clay more
or less "cold,"' differences perfectly well known to farmers, and
capable of being tested by the thermometer. These differences are
due partly to the varying power of distinct materials to absorb the
heat and thus make it ''latent v — as we see in sand versus clay— and
partly to the moisture held by the soil. A soil full of water is cold
partly because the sun's heat is wasted in evaporating the water ;
and, conversely, a sandy soil is warm partly because of the lack of
water. Farmers therefore naturally speak of a " wet, cold clay,''
and a ''dry, warm sand," as the two types or extremes, while, of
course, there are countless variations between these two.

In the case of the soil the temperature seldom goes over 150°
Fah., even in hot, arid regions, and in our own "temperate"
regions rarely over 100" Fah., but it may go a long way below
freezing point at the other end of the scale, and anything that
tends to chill it is harmful to plant growth and even to the live
stock grazing on it. The sun is the source of all heat, and therefore,
the top soil — like the atmosphere — is warmest in summer time, and
the heat penetrates a short way downward as regards diurnal
variations, but beyond this small depth it is only the seasonal
variations that are noticeable.

The evaporation of moisture from the surface uses up an
immense amount of the sun's heat. Indeed it is the warming up
of the moisture on and near the surface that keeps damp soils
cold. On a comparatively dry soil, however, the process is
going on as well, so that the heat of the soil never rises too
high.

In addition to the effect which moisture has on the temperature
of the soil, the other great factor, as already noted, is the colour.
It has been mentioned before, that the amount of Beat a black
sul»tance can absorb from the sun's rays is very much more than
that of a white one — taking the two extremes of colour. Thus
a white and a black sand alongside of one another, and subjected

44 SOILS : THEIR NATURE AND MANAGEMENT

to the same conditions, showed temperatures of 104° Fah. and
laD'S0 Fah. respectively, a difference due solely to the colour.

In the table given below is shown the average temperature of
various soils in the ordinary damp state in summer weather, from
which it will be seen that the temperature variation, due partly
to colour and partly to other factors, among ordinary soils may
be as much as 14° Fah.

Deg. Fah.

Peaty . ' 86-5

Sandy .. 80-0

Loamy 80

Clayey 77

Chalky 73

The specific influence of the component " Proximate Constitu-
ents " no doubt has much influence on the temperature, but it will
be noticed in the above table that the blackish peat has the
highest temperature, and the whitish chalk the lowest. Now
this variation may make all the difference between a "warm"
genial early soil and one that is the reverse : the extra heat
grows the crops much more rapidly, finer varieties can be grown, and
harvest may be ten to fourteen days earlier in autumn.

The quantity of heat necessary to raise the temperature of
a body one degree is called the specific heat, and in the follow-
ing table the differences of the specific heats of various soils by
volume are shown, taking water as 100: —

Dry. Wet,

Water 100 . .100

Peaty 30. . .58

Sandy Peat 21 . . 72

Loamy 18 . .53

Clayey 15 . . 61

Sandy 12'5 . 34

It will be noticed what a difference there is between a wet
and a dry state of the soil. Also what influence its absorptive
power of moisture has on the amount of heat required to warm
it. It will also be seen from the table what a waste of the sun's
heat there is in warming the water in the soil compared to that
needed to warm the soil itself.

The average figures for medium arable soils run from 20
to 23 in the dry state : this means that if it takes 100 " units "
of heat to warm up a pound of water 1° it would only require

THE PHYSICS OF THE SOIL 4."i

about 20 to 23 to warm up a pound of dry soil. This is the ex-
planation of why wet soils are "cold": the sun's heat is wasted
in warming the moisture in the soil, and the soil itself is thus
prevented from absorbing the heat, and the crops do not get
the warmth necessary for vigorous growth, and become late and
stunted. Drainage of the land, so as to remove superfluous moisture,
is immediately followed by a rise in the average temperature of
the soil — sometimes as much as 8° or 10° Fah.

The average temperature of the soil in England is about 1° Fah.
higher than that of the atmosphere, and the average temperature of
the subsoil becomes slowly higher as we descend at the rate of
1° Fah. for every fifty to sixty feet. This subterranean heat, however,
has no appreciable influence on surface conditions ; it is only the
heat from the sun and the reception of it by the soil that concerns
us as farmers.

Of course there are many other circumstances which influence
the temperature of the soil and the changes in it. The aspect of a
field— whether it face3 the sun or away from it — is one factor, as will
be detailed later on ; a heavy coating of manure, if ploughed in, has
been found to raise the temperature for a time as much as 3° Fah.
from its fermentation, while if left on the surface it acts as a mulch
by keeping the heat in and the frost out and thus promotes the
growth of the grass, or other crop, in the same way as gardeners
practise with fruit trees and various garden products. In like
manner a coat of grass keeps the temperature up in winter by
preventing the ingress of frost, so that grass land will plough for
several days after the setting in of frost when bare stubble is frozen
up. On the other hand, the grass prevents the ingress of heat so
that the thaw takes place much more slowly than in the case of bare
land, and thus the plough can be started again more quickly after
frost on the latter.

The presence of stones on the surface decidedly "warms" it. A
stone is a piece of solid, siliceous matter and, like sand, is easily
warmed up and as easily parts with its heat to the surrounding soil
in which a crop may be growing ; therefore, the crop thrives more
quickly. Cases have occurred where the picking of stones com-
pletely off the surface has retarded the harvest by four days. All
large stones must be removed so as not to interfere with cultivation,
but the smaller ones make surface "earlier" as well as more friable
to work.

Even the ordinary operations of cultivation, rolling, etc., in-
fluence the temperature among other things, and is one of the ways

46 SOILS: THEIR NATURE AND MANAGEMENT

we can improve or control the matter by artificial means. We shall
discuss this method when we come to the subject of " Tillage."

As the amount of heat received from the sun on a given square
yard varies according to the season of the year, the question naturally
arises how far this seasonal temperature affects the soil downwards
by conduction. In general terms the daily range (between night and
day) goes down three feet ; the annual range (between summer and
winter) penetrates 40 feet, but is felt very little beyond 25 feet
down. The summer heat reaches the depth of 24 feet on January

60°

/'

v_

if

■^ s.

-^Z-'-

\

N>

5o°

>v

. X

x

^.

\

\

\ "*•

0

40

/'

<'

\

/'

**■*-

/

\
\

•*,r,°

v-

y

v/

DEC.

JUNE

DEC.

Fig. 6. — Diagram of Monthly Soil Temperature at Half a Foot,
Three Feet, and Six Feet Deep.

4th, and the winter cold on July 13th — thus reversing the seasons.
In one instance at a depth of three feet the average summer tem-
perature was 57° Fall, and the average winter temperature 47° Fah.,
with many variations, as shown on diagram, but the average of the year
taken as the result of many trials is shown in the following table : —
Average annual mean at 3 feet is 45'8C Fah.
6 „ 461° Fah.
„ 12 „ 46-4° Fah.
„ 24 „ 46-9° Fah.

Where it is necessary to have the water supply cool, as for dairy
purposes, the pipes must be buried at least three feet, therefore, as
at lesser depths the water would get warmed in summer. Well
water is noted for its coolness because it has the temperature of the
lower layers beyond the reach of the sun.

The radiation of heat from the soil into the atmosphere is very
great during the night, and begins as soon as the sun sets. This is
retarded by a cloudy sky which reflects the heat back again or by

THE PHYSICS OF THE SOTL 47

the wind which mixes up all the strata of air, and thus prevents the
cold layers from settling near the ground. When, however, the sky
is clear and the wind still, we have the conditions favourable for a
summer frost, and in many countries abroad this is fatal in a large
proportion of seasons to the crops, while even in our own country
potatoes and other crops are often cut clown. Anything that will
prevent radiation, therefore, and keep the heat in the soil or the air
directly over the soil will be of value. In practice abroad, for
instance on the prairies, it is customary to light " smudge fires "
with any damp rubbish so as to make a lot of smoke and vapour, and
thus cloud over the crop and keep the heat in, but we have not yet
done so in this country, though gardeners adopt many expedients
on a small scale to this end.

XIII. -Tilth

Tilth is the condition of looseness and friability among the
particles of soil necessary for the healthy growth of the crops. In its
natural state in grass or woodland there is generally no tilth at all,
and consequently only the natural plants of the district — grass,
bushes, trees, etc. — will grow and thrive. Immediately we try to
grow the cultivated crops of the farm we must cultivate the soil to
suit them, because they have been developed artificially by cultiva-
tion and other treatment — some in prehistoric times like wheat, and
some in recent times like the sugar beet. Cultivation in all its various
forms is simply the making of a tilth in the soil to suit the seeding
and the growth of the artificial plants which form our farm crops.

The making of tilth by means of the various implements of
husbandry will be discussed later on, so that here it may be
merely pointed out that the more we can comminute the soil, break
up the lumps and mix them, the better it will be for the crop. The
tendency of both the science and the practice of farming in
recent years is to insist on increased tilth in the soil and to reduce
the amount of manure used.

Most every soil within the top nine inches or so contains enough
fertility to grow a hundred crops if it can be got into a soluble or
accessible state, and the " acts of husbandry " which we carry out in
tilling the soil are all for the purpose of pulverising, mixing, aerating
and otherwise making what we call good tilth, so as to either set free
the elements of fertility, or at least open up the soil so that they
may be available for the roots of the crops.

It has been abundantly shown by experience that a rich soil will

48 SOILS : THEIR NATURE AND MANAGEMENT

not grow good crops without proper cultivation, while an inferior
one will often grow fairly good crops if the tilth is all that it should
be. It has also been shown that manures will not force a crop to
grow where the cultivation is deficient.

Everything therefore points to the fact that in the growth of the
artificial plants, which constitute our farm crops, tilth comes first,
fertility of the soil second, and manuring third, and the modern
tendency is to cultivate more and manure less — a system which,
seemingly paradoxical, does not impoverish the soil.

One of the primary practical uses of good tilth is to supply a
proper seed bed. It is important with all young seedling plants
to give them a good start in life, as it were, for if stunted in tbe critical
early stages nothing will make up afterwards for the damage done.
The production of a loose, mellow, friable surface is particularly
desirable for a seed bed, and for this reason early tillage is necessary.
When the soil has been ploughed or otherwise cultivated in suf-
ficient time to permit of the action of the weather— and particularly
that of frost — on it, then it falls into a nice mealy state very suitable
for further tillage in the spring time. If, on the other hand, the
cultivation is done late, and especially if the soil is wet, then we
have the formation of clods, and the soil is left lumpy, and it may
take a whole season to cure this, while the crop suffers accordingly.

Frost is the great producer of tilth, and nothing done by imple-
ments and any amount of labour can equal the effect of it. The
expansion of the moisture in freezing breaks open the lumps, clods,
and pieces of soil in a way that nothing else can do. To get the full
benefit of frost, however, it is necessary to have the ploughing done
in the autumn and early winter, and therefore good farmers always
try to have this work well forward.

As a rule the formation of a tilth is confined to the top soil.
There are reasons why we sometimes do not want it to penetrate too
deeply, but prefer to have the lower layers firm and moist after
cultivation, rather than loose and friable, in a dry district or a dry
season, as will be immediately shown.

A fine mealy surface, however, is generally desirable, and hand
and horse hoeing are employed to produce this condition. When a
soil is in a very fine state of tilth and heavy rain falls, the particles
are apt to " run " together, and the condition known as " soil
capping " results. This state is very detrimental to the crops, and
in the case of root crops hand and horse hoeing must be carried on
as soon as the soil is again dry enough. To prevent this tendency
as much as possible, the tilth must not be too fine, while the trouble

THE PHYSICS OF THE SOIL 19

varies according to the kind of soil, being worst on one of a clayey
texture and least on a sandy one. A soil deficient in tilth, or which
has become "capped," is very liable to crack and leave great fissures
in dry weather — especially in clay soils— and surface cultivation
must follow to prevent or cure this.

A few words are necessary to explain the physical effects of tilth
on the soil itself. First, the surface cultivation prevents excessive
loss of water from evaporation in dry seasons, and enables the roots
of the crop to get more moisture. When the top inch or two of soil
is loose the capillary power is destroyed, and therefore the soil water
is not raised to the top to be lost by evaporation, but remains just
under the loose " mulch" where the roots get it, so that in this way
the water contents of the top soil are increased.

In a wet season or in a wet district no attention need be paid
to this, but in the dry eastern counties of England this system has
to be followed to make turnip and mangold growing a success, and
the crops are grown "on the flat," and not on ridges, so as to get the
fibrils nearer to the soil moisture, and thus conserve the water.

Even the temperature of the soil is raised a degree or two where
well tilled : there is no waste of heat in evaporation of the moisture
in a dry time, while when the soil is wet it is more quickly dried by
the wind if stirred up, and it thus gets sooner warmed again.

CHAPTER III.— THE PHYSICAL GEOGRAPHY
OF THE FARM

We have seen what the soil of a farm is and what takes place in it,
as it were, when we cultivate and grow crops upon it. We have now
to see how circumstances and the surrounding conditions affect
a farm, and influence its power to grow crops and pay rent. These
are for the most part outside the farm itself, or at least affect a
whole countryside together. For purposes of systematic study they
may be grouped under (1) Latitude, (2) Altitude, (3) Climate, (4)
Rainfall and Water Supply, (5) Shelter, (6) Aspect, (7) Contour, (8)
Sea Influence, (9) Natural Vegetation.

I.— Latitude

It is of course a matter of common knowledge that tlrjre is a very
great difference between the climate of the north of Scotland and
that of the south of England — to take the two extremes of the
British Islands. The explanation of this is that the one is nearer to
the north than the other, and therefore is subjected to a lower
average temperature, to a greater amount of stormy weather, and of
frost and snow, while the day will be excessively short in midwinter
for doing the work. Many other subsidiary matters influence these
phenomena, as will be explained in this chapter, but the general
fact remains that given two farms, alike in other respects, the
northern is worth less rent than the southern one, for the farming
and the cropping must be greatly influenced by these things, while
the conditions of life generally are more desirable in the" south than
in the north.

Isothermal*. — If the average temperature of the atmosphere is
taken for various districts all over the country and a line be drawn
connecting those of the same figure, that line is termed an " isother-
mal." It is found that for the British Islands these lines run from
north-west to south-east across the country, and that the line for the
south-east of England is G4° Fah. and for the north-west of Scot-
land 54° Fah., a difference of 10° Fah. in favour of the average con-
ditions in the south. These ten degrees have a tremendous effect on

50

PHYSICAL GEOGRAPHY OF THE FARM 51

the kinds and qualities of the crops grown. Besides these iso-
thermals due to difference of latitude, there is the temperature of
east versus west ; the east coast is always 2° colder than the west.
The sea equalises the heat at the shore all round our coast, but the
east is colder than the west all the same.

II. -altitude

It is pretty well known that one of the factors which influence
the climate in general, and any farm in particular, is the height
above sea-level. On the seashore there may never be any appreci-
able frost and snow at all, while a few miles inland, but up among
the hills, the winters may be long and severe, and snow may lie
deep and late. This difference may not be wholly due to the
difference of altitude— for proximity to the sea counts for something
in the amelioration of climate— but it is largely due to it. The
influence of altitude may be seen in comparing the weather and
other characteristics of a valley with the adjacent hills ; the mere
height means a lower average temperature, more rain probably, and
more exposure to storm. Even the natural fertility and nature of
the soil depend much on this, for the rains and floods are continu-
ally washing the richest soil material downwards to the valley or
low lands, leaving the hills and higher ground impoverished, as
shown in Figure 1.

We are accustomed to regard the climate of the hills as healthy
and bracing, and so it is, as it is away from any of the miasma
which often develops on low grounds or in the valleys. Over
and over again it has been proved that the air of the mountains
contains far fewer of the floating noxious microbes than is common
in the valleys — as shown by the Swiss in bottling milk in the high
Alps in a way that is impossible in the valleys. On the other hand,
hill-bred folk are usually healthy and hardy because in the course
of ages the more rigorous conditions of life have killed off the
weaklings, and only the naturally hardy have survived to form the
native population.

It is found that the fall of temperature is about 1° Fah. for
every 300 feet of ascent, and therefore, apart from any local
influence, the average temperature will be lower in the hill country
than in the low lying country, or on the seashore, as the result of
mere difference in height. This has a corresponding influence on
the crops and live-stock, and means that we must have hardier

52 SOILS: THEIR NATURE AND MANAGEMENT

breeds or races of stock and crops for the hills than would be
necessary on the plains and in the valleys, and a corresponding
variation in the value of the land.

Besides the lower temperature, altitude generally carries with it
some other drawbacks : there is usually a scantier soil, steeper land,
less nutritive and satisfactory herbage, and a greater rainfall on the
higher grounds, all of which reduce the value of the soil for farming
purposes. For instance, wheat will not ripen over, say, 600 feet
above sea-level, and even other cultivated crops cannot be depended
on over 800 feet in Scotland and 1,000 feet in England. Most of
our ordinary farming land is a -long way below these heights, of
course, but the point has to be studied whenever one approaches the
hill country to look after land, and judged accordingly.

It may also be pointed out that the lower ground, being on the
newer and richer formations, has generally the better soils— marls,
clays, and sands— apart from the question of rain wash or surface
drift, for even in a hilly country the level meadows in the valleys,
glens, or straths are formed of better soil than the neighbouring
hillsides.

Situation in a valley, however, renders a farm more liable to
spring and autumn frosts. This is clue to the fact that on a calm
night the cold air descends, and thus the hillsides under such
circumstances may keep a higher temperature while the valley
drops to freezing point. On a slope on the Downs two stations
about a mile apart were tested in February and March. The one
station was about 100 feet lower than the other, yet it showed
about 1° Fah. lower temperature than the higher station. This
was clue to the downward current of cold air, and the same results
may obtain anywhere else under similar conditions.

III. -Climate

Apart from the individual characteristics of any given farm, the
general climate of the district in which it is situated has much
influence on its ability to yield crops and carry stock. The great
factors affecting the farming are, as we have just seen, distance
from the equator and height above sea level. Even within the
comparatively small limits of the British Islands there are great
variations due to these causes, with corresponding influence on the
fanning. As an example, it is a matter of common knowledge that
a farm on the sea-level in the south of England will enjoy a more

PHYSICAL GEOGRAPHY OF THE FARM 53

genial climate than one, say. on the Grampians, a state of matters
wholly due to latitude and altitude irrespective of a dozen other
influences at work which may affect a given farm. Thus, the west
coast oi Ireland and the Western Hebrides may, and generally do,

enjoy a milder winter than the southeast of England because of the
incidence of the Gulf Stream, while the insular position generally
helps to equalise matters. Still, these differences exist, and must be
taken notice of and allowed for by fanners who propose to hire
a faun in a district new to them.

One who has been brought up and accustomed to working land
in a given district has been habituated to its climate, and instinc-
tively and unthinkingly allows for it ; but when he has to remove
into a new neighbourhood he would be wise to find out what he is
likely to have in the matter of weather, winter snows, etc., etc.
When the change is made from north to south, or from the hills to
the low lands, there are likely to be beneficial results, but if the
change is the reverse way inquiry should be made on these points.

IY.— Rainfall and Water Supply

The rainfall statistics of the British Islands are pretty well
known now. and every physical atlas contains a map showing the
varying intensity of rain all over the country. The average rainfall
of the west coast is 36 inches per annum, and of the eastern side
26 inches, but the local fall of any particular spot may be above or
below these figures.

For instance, parts of Essex and Lincoln only show from 18 to 21
inches per annum on an average, while such places as Glen Croe, in
Argyllshire, and Sty, in Cumberland, run up to over 200 inches.

On the other hand, districts that are usually "dry" in the
ordinary run of years may have a " wet" year, as happened a few
years ago in Essex and the south-east of England generally, when
the usual fall of, say, 20 inches, ran up to 36, with correspondingly
disastrous effects on the crops and soil. Such a state of affairs is
only a temporary accident, however, and the average rainfall is
what a farmer should know.

The kind of farming followed depends to a large extent on the
rainfall. The east side of the country has always been noted for
corn and arable farming, and the west for grass and dairy work,
solely because of the difference in the rainfall. In a wet district
tillage and the proper preparation of the soil for crops is at a

54 SOILS : THEIR NATURE AND MANAGEMENT

discount, while a lot of corn could not be handled in a locality where
rain in harvest time is the normal state of matters.

Per contra, dairying is carried on at extra expense in the eastern
counties, where the grass is liable to disappear in a hot dry summer
and autumn, and lush food becomes scarce and has to be supple-
mented by "artificial'' food-cakes or meals.

Rainfall of course does not wholly depend on the position of a
district with reference to its position east or west, for there are
many modifying factors influencing local rainfall : such as situation
with regard to hills, forests, plains, rivers, lakes, seas, etc., but the
general facts are that our rain clouds in these islands come from the
Atlantic with the west and south-west winds, and that therefore the
western and south-western parts of the kingdom get the first and
biggest share of rainfall, and the eastern and north-eastern get least.
The deviations from this rule are due to local influences which &re
generally apparent, and which of course the natives of a given
district are used to, but a new- comer must take note of and adopt
his system of farming to such deviations.

Examples may best illustrate the influence of rainfall on the
system of farming. A Scottish fanner on coming to the south of
England attempted to grow swedes and turnips in the same way as
he was accustomed to in the north : result, failure, because the rain-
fall was not sufficient to swell the roots and prevent mildew where
mangolds would have succeeded. Again, a farmer coming from
the west of England to Essex failed to grow mangolds till he
learned the practice of growing them " on the flat " combined with
heavy rolling so as to stimulate the capillary action of the soil and
thus counteract the drought : in the west he was accustomed to
" ridging up " the roots so as to carry them above the excess of water
supply.

The rainfall is chiefly dependent on two things in our country :
height above sea level and proximity to the west. The geological
structure is such that the older and harder rocks have the highest
hills and are mostly situated to the west, as in Wales and Scotland
and thus the wettest and highest districts and the oldest rocks coin-
cide. As a rule, all places over 800 to 1,000 feet high have a rainfall
of 100 inches per annum and over, while the low-lying eastern
counties have the lowest amount.

Thus, if a line is drawn from Snowdon to Essex it will cross all
the geological formations from the oldest to the youngest : it will be
downhill all the way, and it will range from the wettest to the driest
parts of the country, as shown in the following table, which alio

PHYSICAL GEOGRAPHY OF THE FARM

indicates how the prevailing farming is influenced by these rainfall
conditions : —

Primary

Secondary

Ter-
tiary
Rocks.

Rocks.

Hocks.

?»

s

;-

~i

i

:

?-

-

c

!

=
~

>§

"£

g

^

-s

^

^

=

^

-

£

^

Rainfall : approximate

inches per annum

100

95

4.-)

35

30

27

25

22

20

Height above sea level :

approximate feet

900

700

in..

300

270

250

230

220

200

Percentage acreage

under com

11-1

20 3

■21-4

- .

25-7

29-8

42-0

42-3

46-3

Percentage acreage

under grass

7o-9

63*8

»v2

52 -y

56-4

52-8

314

29-7

24-2

11*'//-,- supply. — Intimately connected with the rainfall of a
district is the water supply of the fields and farms. A "well-
watered farm " is one that is " desirable " in one respect at least, for
the household and live stock must be supplied somehow with drink
during the hot months of summer, and a fair supply of wells, ponds,
ditches, and watercourses is of the first importance.

We can always find plenty of water by boring far enough down-
wards, but the conditions of an ordinary farm seldom justify the
outlay necessary to go down, say, several hundreds of feet and fix
the necessary pumping machinery. Even where the "water table,"
or surface of the saturated body of the underground layers, is within
thirty feet of the surface, and can be tapped by a common hand-
pump, the labour necessary to supply a lot of stock will be very
considerable, though nowadays we can adopt a windmill pump.

We have in any case, therefore, to depend more or less on
ordinary surface or spring water derived directly from the rain
supply. The supply for the homestead may be brought in pipes
from a distance or pumped from a well, but the supply for the stock
out in the fields is quite another matter.

Access to a river or a stream which never runs dry may be worth
many pounds to a farmer in a year, while a sufficiency of ditches or
ponds about the fields is absolutely necessary. The amount of rain
that falls on every farm is quite sufficient to supply it if the water
could be saved, but usually it runs off into the streams and is lost,

56 SOILS : THEIR NATURE AND MANAGEMENT

unless it happens to go to supply a spring yielding a steady
flow.

Of course, much can be and should be done to save rainwater.
A pond may be dug at a convenient corner so as to supply several
fields, or a dam may be made across a hollow, but these cost money
to make, and the outlay is a set-off against the value of the farm, so
that what may be called a "natural" supply of water about the
fields is of great value to a farmer.

It is of course understood that the water is of good quality. If
there is any taint of sewage the taint mast be stopped or the water
discarded, and this is a point specially to be seen to in the case of
wells situated in or near the farmstead. In certain mining and
manufacturing districts, again, the supply may be polluted by foul
water directly discharged into the watercourses.

There is a very great difference between the various geological
strata in their power of holding water and yielding it for farm
purposes. As a rule the clay formations are "dry," that is, there is
no volume of underground water in them that can be tapped ; on
such beds as the London Clay, the Gault Clay, Kimmeridge Clay,
Oxford Clay, Upper and Lower Lias Clay, and Keuper Marl, ponds
or dams require to be made to catch the surface water, unless it can
be brought in pipes from an adjoining deposit.

All the limestone beds — Chalk, Oolite, Lias, and Carboniferous —
are full of water, but it is always hard and may be at a great depth.

All the sands and gravels are also full of water, more or less soft,
and as these are generally near the surface they are very often the
most convenient sources of well or spring water on a farm where
surface pollution is not allowed to take place.

The older rocks, composed of grits and shales, also hold much
water in their fissures, and it is of soft quality.

There are very few farms on which water cannot be found some-
where within their bounds, at a reasonable depth from the surface,
though it may have to be pumped up. If it can be found above the
homestead, then a gravitation supply may be arranged ; even the
making of a large pond by digging or damming up to catch the
surface water may pay, and will be quite satisfactory if pollution is
prevented.

Y.— Shelter

All our domestic animals and plants, having been developed by
human care, always grow better and give better returns when
sheltered and kept under comfortable circumstances. A thoroughly

PHYSICAL GEOGRAPHY OF THE FARM 57

equipped farmstead is necessary to house all the livestock, crops, etc ,
and if it does not already exist it should be made.

Again, the homestead itself should be in a sheltered nook if
possible, not too low down, and not too far away from the centre of
the land, and in a position to get the sun as much as possible.

Lastly, the sheltering of the whole farm from storms is a matter
to be attended to. In this country our cold and stormy weather
mostly comes from the north, north-east, and east, and consequently
a range of hills or high ground in these positions will improve the
general climate of a farm very much, and make it more valuable
for farming purpose?, while exposure will reduce its value.

On the other hand, the sheltering may be improved artificially by
planting woods or strips of plantation along the exposed sides, while
all " broken "' land — /.<-., rocky ground, steep sides near brooks and
rivers, and places which cannot be cultivated, or cut for hay if in
grass, should also be planted. This, however, is the landowner's
work, and a tenant has to take things as they are, but he will be
wise to note such matters.

Too much timber is, of course, a drawback, because it is apt
to lodge excess of game, and therefore the happy mean must be
aimed at.

Even a big hedge is not to be despised. It is. no doubt, un-
sightly on a farm to leave the fences untrimmed, but they certainly
act as windbreaks, and immensely improve the comfort of the live
stock. A good healthy hedge, too, is a very good indication of the
cropping power of the land.

A stranger visiting a district for the first time can generally get a
good idea of the effects of the want of shelter by noticing the trees :
if a given farm or the whole neighbourhood is exposed the trees will
grow lopsided, and hang away from the blast. Even the thatch on
the stacks will give a hint ; if roped down with string or yarn it
means there must be a lot of storm and wind, while if left bare it
will indicate a reasonable amount only of wind or exposure.

VI. — Aspect

Does a farm •' lie to the sun " or does it not ] is a question always
asked by farmers in discussing the capabilities of any farm. A farm
on a plain, like the prairies of the West, or on the bottom of a wide
valley, like the "carses" or estuaries of some of the rivers in the
British Islands, cannot be said to have one kind of aspect more than
another, but in the greater part of these islands the laud is at least

58 SOILS : THEIR NATURE AND MANAGEMENT

undulating if not actually hilly or mountainous. The consequence of
this is that the fields have more or less of a slope, and if the slope
looks southward towards the sun it is worth more for farming
purposes than if it sloped to the north.

This is due to the fact that the sun's rays strike the land with a
southern aspect more directly than when the slope is the other way,
for, indeed, the northern aspect of a range of high hills may never see
the sun at all — at least in winter time. {See Fig- 7) This state of

Fig. 7. — Aspect. Let S represent a Ray of Sunshine : On Slope A B
it is Concentrated on to the Smallest Space, on Level C D
it is moke Widely Distributed, -while at E F it is Further
Weakened by Dissipation over twice the amount of Surface
there is at a b.

matters has a vast influence on the farming value of the land and
the working details of it.

In a valley known to the writer the crops on the north side
are always a week ahead of those on the south side (with a
northern aspect), and as early potatoes are largely grown this means
many pounds more per annum received for the produce grown on the
iiorth side where the slope faces the sun.

In the case of the natural cover — pasture — there is more liability
to " fogging up," that is, to get overgrown with various mosses, on
the northern exposure than on the southern.

When the slope is at an angle of 25° to 30° it receives the sun's
rays at the nearest approach to a right angle in our latitudes,
and consequently every acre receives the maximum possible amount
of sunshine, but a slope of this steepness is uncomfortable to work

PHYSICAL GEOGRAPHY OF THE FARM 59

on or cultivate, and may have to be ploughed with a " one-way "
plough across the face of the slope, if ploughed at all.

The difference between the various aspects may be seen any
winter by noting the falling of the snow and its melting when the
thaw comes : the slopes facing the north round to east get the most
snow, and get it oftenest, while the other sides of the hills or the
valley get little, and it melts more quickly.

All this has a very great influence on the treatment of stock and
the cultivation and other work of the farm, and the practical farmer
takes note of these things in assessing the farming capabilities of a
district or a particular farm.

On the plains in various parts of England — the newer formations

these differences do not exist, for where the ground is not actually

ven or level it may be only slightly undulating, and the differences

be infinitesimal, but in many cases even there the difference between

a very small slope to and one away/rowz the sun is quite perceptible

in its effects on the soil and the crops.

The difference in temperature from aspect alone is very consider-
able. The soil on the slope to the north may receive one-third less
sunshine than one to the south, and be 7° to 10° Fah. cooler in
temperature. Even a gentle slope to the south may be from 3° to
v Fah. warmer than the same soil on the level.

Yet another point arises which depends on the aspect of the
fields. In this country the prevailing winds come from the south-
west, as does by far the greatest amount of the rain. The result
is that the slope which faces that direction and gets the greatest
share of sunshine also gets the greatest force of the rainfall. Now,
as before explained, the rain-wash on a slope has much to do with
the texture of the soil, and so on the .south-western slope we expect
to lind much of the finer earth washed out and the soil more sandy
or granular than the same kind of soil with a different aspect.
Actual investigation has shown this to be the case, and perhaps
this fact explains why some of the finer grasses are found on the
north-eastern sides of a hill, and why the sheep prefer to graze there
in spite of the tendency to fogginess. There is no end to the compli-
cations introduced into farming by the freaks of our salubrious
climate.

VII, Contour

The two extreme examples of the differences of contour to be met
with on farms are the levels of a marsh, plain or meadow and the

00 SOILS : THEIR NATURE AND MANAGEMENT

ruggedness of a precipitous mountain. We meet with both extremes
within our islands and with countless combinations of variations
between them.

At the first glance it will be realised that the horse and manual
labour on a farm will be very largely affected by the levelness
or steepness of the land, and that labour will be most conveniently
carried out on the level ground, but be next to impossible, or quite
impossible, in a rocky, hill country. Apart altogether, therefore,
from the nature of the soil, its fertility, altitude, aspect, and a score
• of other factors influencing the farming, the mere nature of the
surface of the farm as regards its ups and downs will have a tre-
mendous influence in determining the kind of farming to be
followed.

In a hilly and rocky region, sheep- and cattle-farming only can
be followed, and cultivation will be limited to the few alluvial spots
alongside the streams in the valleys ; in a wide level or undulating
country every acre can be under the plough if so desired, and the
live-stock farming is determined very largely by the cultivation.

While level land is very convenient and suitable for arable work,
it must, of course, be pointed out that dead levelness (if absolute
levelness of land could exist) is not desired because of drainage con-
siderations. The ground in its natural state absorbs less than a half
of the rainfall, and the rest has to run off the surface somehow into
the nearest ditch and brook, and then to the sea. All land has
therefore been deposited— or subsequently weathered and washed —
with some slope naturally, and where this is not so a marsh or a
lake is formed.

In modern farming, however, the natural drainage off the
surface is not enough, but has to be aided and developed by subsoil
"thorough" drainage with pipe-tiles laid in trenches at regular
intervals all over the land and covered in. These pipes must have a
"fall" of not less than eight feet to the mile, but as much more as
possible without going to extremes, and therefore the contour of the
land most desired is one with sufficient undulations or slope to keep
it free of surface water and to carry the superfluous underground
moisture off easily.

The contours of a district depend almost entirely on the nature
of the underlying geological formations, and as the nature of the
soils depends on these as well, it is no wonder that Arthur Young, in
his historical journeys and inquiries into the farming of England, at
a time geological study was undreamt of, came to the conclusion that
the contours wholly determined the nature of the soils.

PHYSICAL GEOGRAPHY OF THE FARM 61

On the older formations the contours will be steep and precipitous ;
on the newer ones more moderate, while on the recent formations
we find the most of the low-lying, undulating or level districts of the
valleys, fens, meadows, carses, etc.

The contour features of a district depend so much on the nature
of the geological formations below that it is quite possible for anyone
who has studied scenery to tell what these formations are, merely
from their appearance in the distance, for each kind of rock has its
own contours and " scenic " effect.

The contours of a farm or district influence greatly the exposure,
shelter, aspect, etc. On a plain approximately level there is no
natural shelter, and artificial shelter with trees and buildings has to
be made ; in a hilly district there is abundance of sheltered hollows
which add greatly to the value and amenities of a farm and counter-
balance the drawback of steepness : but a kind of medium is more to
be desired.

YIII.— Sea Influence

One of the great factors which control our climate as a whole is
the sea which surrounds these islands. The general temperature of
the coast-line all round is higher than farther inland, and it is also
kept more equable. Farms on the shore are, as a rule, " very
desirable ' for these and other reasons, if there are no drawbacks
such as a rocky country, a great rainfall or anything else that counter-
acts the value of the sea breezes. In considering the particulars as
to sea influence, we find that the Gulf Stream is of the first moment.

Chilf Stream. — The great factor in equalising and improving our
climate is the Gulf Stream, that huge body of warm water that flows
across the Atlantic and washes our shores. If it were not for this,
our winters would be as bad as those of Labrador. It is the
influence of this that makes the climate of the west of Ireland,
the Scillies, etc., so mild — if wet — and conduces so much to the
production of early crops in these districts.

An example of its influence is given by the growth of early
potatoes in the south of Ayrshire : this district is just opposite the
opening between Ireland and Cantire, and is free from spring
frosts, and so here for over a generation early potatoes have been
grown. In the same way the Channel Islands and the Scillies have long
been celebrated fur early flowers and vegetables, and the west of
Ireland will also be at some future day, when the natives wake up
to the potentialities of their country.

62 SOILS : THEIR NATURE AND MANAGEMENT

Wherever the shores of these islands face the west that district
has its climate profoundly modified for the better in the matter of
temperature, and has its winter and spring growth of crops immensely
helped.

The influence of the sea is seen in our islands in another way :
the average winter temperature all round our coasts is the same at
sea-level, 37° Fah. fur the east and 39° Fah. for the west. The
influence of latitude is felt in summer in making the south country
warmer than the north, but the tempering influence of the sea shows
in the cold weather. This influence does not go very far inland, or
very high above sea-level, and is therefore one point very largely
in favour of a shore farm.

IX.— Natural Vegetation

As the soil has been largely made or modified by the growth of the
plants on it, so, in like manner, the plants have been modified by
the action of the soil on them, and each type of soil has developed a
natural flora to suit itself, which would not thrive so well if trans-
planted to another kind of soil — assuming that other circumstances
were the same. We see this very distinctly exemplified in the case
of timber trees : oak thrives on clay, elm on loam, beech on lime-
stone and marl, birch and pine on poor sand and gravel, and so on,
and it is almost possible to tell the nature of a soil from a distance
by noting the prevailing kind of timber tree.

Coming down to the smaller plants, we find such examples as the
sand grass (Ammophila arundinacea) on the sandy seashore :
Yorkshire fog (Holcus lanatus) on peat ; rest-harrow (Ononis
arvensis) on clay ; horsetails (Equisetum arvensis) on wet sand ;
spurrey (Spergula arvensis) on sandy loams ; red poppies ( Pajiaver
Rhoeas) on gravelly soils, and so on, with a score of similar cases,
characterising the different soils.

Some plants, for instance, such as lupines, serradilla, gorse, and
heather, are intolerant of lime in the soil. Other plants, again, such
as the beech, yew, and box, like a limy soil, while among crops, clover,
beans, and peas like a fair amount in the soil ; the "boiling" quality
of peas, indeed, being considered to be due to the lime.

It is, indeed, quite possible to draw up a list of the plants which
are peculiar to, or thrive best upon, the different classes of soil —
from trees downwards —while some individuals are confined to the
soils of certain specific geological formations. The most common
and extensive cases may here be given by way of example ; such

PHYSICAL GEOGRAPHY OF THE FARM

63

cases as take the attention of anyone passing through a district or
making a cursory examination of the outstanding features of a
farm : —

Sandy Soil

Conifers

Lupine

Birch

* Birdsfoot Trefoil

Rowan

Serradilla

Spanish Chestnut

Couch Grass

Hazel

Spurrey

Holly

Poppy

Gorse

Marigold

Broom

Sandwort

Bracken

Loamy Soil

Elm

Coltsfoot

Ash

Charlock

Sycamore

Wild Radish

Chestnut

Bindweed

Apple

Yellow Rattle

Pear

Couch Grass

Yarrow

Groundsel

Ragwort

duckweed

Clayey Soil

Oak

Primrose

Hornbeam

Trefoil

Poplar

Wild Oat

Restharrow

Field Foxtail

Knotgrass

Marsh Bent-grass

Buttercup

Mayweed

Wild Carrot

Marly

and Calcareous Soil

Beech

Gorse

Larch

Sainfoin

Wild Cherry

Lucerne

Yew

Kidney Vetch

Juniper

White Clover

Box

Wild Parsnip

Peaty Soil

Birch

Barren Brome-grass

Heaths

Yorkshire Fog

Cotton Grass

Quaking Grass

Soft Brome-grass

(>+ SOILS: THEIR NATURE AND MANAGEMENT

The above lists are not intended to convey the impression that
the plants named are confined to the respective soils ; they are only
intended to indicate the preferences that the plants seem to have,
and that where found growing naturally they "predominate" on
some soils and are scarce or absent on others.

So striking is the suitability of some trees to certain formations
that the late Prof. Buckman compiled the following table to illus-
trate the fact. The figures represent comparative values, and thus
indicate the failure or unsuitableness of our standard timber and
fruit trees, as well as their successful growth, under different soil
conditions : —

Bocks.

Oak.

Elm.

Beech.

Pine.

Apple.

Pear.

Chalk

2

4

8

5

2

0

Greensand

3

7

0

3

3

1

Gault

6

6

0

0

4

1

Oxford Clav

10

8

0

1

6

0

Oolite Limestone

1

4

10

o

2

0

Lias

5

10

0

1

10

3

New Eed Marl ..

.

12

0

2

8

0

Mountain Limestone

2

2

3

1

1

0

Old Red Marl . .

8

10

0

1

15

8

While the native plants of the soil thus have various predilections,
and predominate in some districts and disappear in others, the
cultivated crops of the farm have similar tendencies. Thus clay
land suits wheat, oats, and beans best, and the best qualities of these
are grown on the heavier soil. Barley likes a loamy or intermediate
soil, while rye is the "corn" of light sandy districts.

Among " root " crops, mangolds thrive best on the stiffer soils,
while a "turnip soil " is pre-eminently one of a loamy, friable nature,
and carrots thrive best on the lighter sandy variety. Potatoes in
particular are influenced by the soil. Thus the red loamy soil of
Dunbar is notable for growing the "Dunbar Beds," the finest kind
of potato in the market, while the Fens produce the " BlacKlands,"
which are not worth nearly so much per ton.

Thus there are differences in the crops from the influence of
the soils altogether independent of the cultivation and manuring.
Many of these differences are of world-wide significance, while many
are only known locally, but they have an important bearing on the
systems of farming and are fully recognised by practical farmers.

PHYSICAL GEOGRAPHY OF THE FARM 65

A soil maybe very much " improved'' by draining, liming, manuring,
etc., but its original characteristics and possibilities remain the same
to a very great extent and cannot readily be altered.

These differences in the natural vegetation may be said to be due
to the texture and chemical composition of the soil alone, but, of
course, the " climate" of a particular spot, its exposure, altitude, etc.,
have a great influence on the character of the vegetation as well.
********

There are so many of these physiographicil factors working at
cross purposes, as it were, that it is sometimes rather difficult to
unravel the subject and assess the value of each in influencing the
cropping and stock-carrying capacity of a farm. Nevertheless, it is
necessary to make some attempt at judgment in this line, where a
v*ould-be farmer is proposing to rent a given farm. A man who is
already settled in a farm will equally find it to his benefit to take
notice of these conditions and circumstances and farm accordingly.

CHAPTER IV.— THE IMPROVEMENT OF THE

SOIL

There are several important operations or methods which can be
carried out for the purpose of permanently improving soils. A
piece of land — even a rich prairie — in a state of nature is not just
ready for farming until many things have been done to or on it. It
may be excessively wet, or excessively dry ; it may be deficient in
lime ; it may be stony or bouldery ; while, of course, it needs "equip-
ment " with buildings, fences, roads, etc. Apart from these latter,
there are various methods of improving the soil, as distinct from
" equipping " the farm, and these we may now proceed to discuss
under divisions : (1) Draining, (2) Stone Clearing, (3) Liming, (4)
Irrigation, and (5) Manuring.

I. -Draining

One of the first things that requires to be done to improve land
in this country, in nine cases out of ten, is to drain it properly. The
actual method of carrying out the engineering work of draining a field
will be treated in its proper place, and only the facts pertaining to
the effect of drainage on the soil can be explained at this stage.

There is a heavy rainfall in the United Kingdom generally : even
in the Eastern Counties it reaches 20 inches per annum, while in
Cumberland 225 inches are reported in some spots. Of this rainfall
part soaks into the ground, part runs off into the ditches and
streams, and part is directly evaporated. That which soaks down
into the ground gradually accumulates in the lower layers, until
it rises high enough to run off at some outlet in the shape of a
spring, or oozes out on the sloping side of an incline to make a
piece, of wet, swampy land. Where this subterranean body of
water rises to within less than thirty feet of the surface it is
possible to get at it by a well, and to raise it by a common pump.
The surface of the water in the well shows how far up complete
wattr-loggedness exists, but between that "water-table," as it is
called, and the surface of the ground there are varying proportions

6(3

THE [MPROVEMENTOF /THE SOU. 07

<>f moisture preseut. Thus on the surface in dry weather there may
be almost absolute dryness -. a foot or two down. 20 per cent, of
water present ; another foot or two farther down, 40 per cent,
present, increasing in ratio until the actual body is reached with 100
per cent, of saturation water. oV Fig. 5.)

Xow, all plants require moisture, but on stiff retentive soils, or on
the heavier soils in continuous wet weather, there may be too much
water held by capillary action or by temporary saturation, ending
in the "souring" of the land, the chilling of the roots of the plants,
the prevention of the access of the air with its oxygen, and the
eventual killing, or at least stunting, of the cultivated plants on the
soil.

By putting rows of pipe-tiles at regular intervals up and down the
fields at a depth of two to three feet the surplus water is removed,
the interstices in the soil opened to the passage of the air and the
roots of the crops, and the temperature of the soil raised.

The beneficial effects of draining are so many and varied that it
is desirable to take them up and explain them categorically as
follows : —

1. Textwre improved. — The mere removal of the excess of water
results in a certain amount of curdling or granulation of the clay in
a stiff soil. Xo doubt this is partly due to the oxidising action of the
air which follows the removal of the water, and to the salts in
solution in the soil water — such as bicarbonate of lime — as the
removal of the excess immediately causes its circulation, either
downwards by percolation or upwards by capillarity. The practical
result of this is that the soil becomes more friable and more easily
worked by the implements of husbandry, apart from any other treat-
ment. This improvement goes on very slowly, of course, but when
once the clayey material has shrunk into blocks by actual fissures, or
has merely had the formation of curdled grains, it is never so sticky
or unworkable again.

■2. Roots go deeper. — When the stagnant water is gone the roots
have a chance to penetrate deeper. If the under layers are full of
sour and poisonous water roots can only grow downwards for a
limited space in the top soil, but if the excess of water is removed
and the soil is sweetened then they can descend into the deeper
. s, and thus have a wider range of feeding ground. It is in this
way that draining prevents the evil effects of a drought. The roots go
so much deeper that the crop is independent of surface conditions
and gets enough capillary water to keep it going.

3. Temperatv/re raised — The removal of the excess of water

68 SOILSj THEIR NATURE AND MANAGEMENT

reduces the amount to be evaporated, and thus the sun's heat warms
the soil without wastage, while the air and rain will get a chance of
carrying the surface temperature downwards. Water is a poor
conductor of heat, and therefore the warmth of the sun's rays is
carried very slowly into the soil when it is wet : if drained the
ordinary action of conduction will warm up the particles of soil
much more quickly. There may be a difference of from 5C to 10°
Fab. in temperature between a drained and undrained soil simply
from the presence or absence of excess of water.

4. Water allowed to get in.— It has been said that draining is
carried out not so much to get the water out of the soil as to get it
in. The rain that falls always brings down a little fertilizing matter
(such as ammonia) with it, while any manure on the surface supplies
more. If the soil is already full of water this fresh lot cannot soak
downwards with its load of fertility, and thus is apt to be lost in the
nearest ditch. "When, therefore, the pores of the soil are open the
fresh showers have a chance to percolate downwards, and cany with
them all the extra fertility in solution into the body of the soil.

Paradoxical as it may seem, draining makes the soil more moist.
It substitutes the film of capillary water — in which only the roots of
plants can feed — for the sodden state, while this film water is most
plentiful in the warm growing season, and there is a greater cubical
space in which it can form and serve the roots. The total outcome
of this is that a soil is drier in a wet time and moister in a dry
season than before draining.

5. Bain-washing prevented. — If the rainwater cannot immedi-
ately percolate downwards it collects on the surface, and when in
sufficient quantity it runs off down the furrows and hollows to the
nearest ditch. If the quantity is excessive it will carry with it a lot
of the finer soil, but even where this does not happen it will yet
carry off in solution all the elements of fertility from the surface.
This is, perhaps, most noticeable after a thaw where dung has been
carted out and spread on the surface while it was yet frozen. When
the thaw comes the soil below is hard so that the surface water
cannot get down, and therefore runs off into the nearest ditch carrying
with it the brown essence of the manure. This is exactly what
happens with waterdogged land, though perhaps in a lesser degree,
and the removal of water by drain-pipes below is the first necessity
to cure the evil, while if followed by subsoilingor trenching so much
the better.

6. Linn and manures act better. — Draining is imperative before
we can get any good from a dressing of any sort. Apart from the

THE IMPROVEMENT OF THE soil, 69

probability of the manorial compounds being actually washed oft' the
surface, there is the certainty that a wet soil will not be benefited
wry much, even when the manure or lime is actually in the
soil. The useful microbes cannot work in stagnant water, the oxygen
of the air is not brought into contact with the components, and thus
the benefits are lost.

7. Crops grow better. — As a result of the improved texture of
the soil, the better capillarity, oxidation, and action of manures, etc.,
crops of all kinds grow better. This, of course, is the principal
ultimate result that is desired, and to which all the other things are
expected to tend. On a natural pasture the coarse "bents," rushes,
and other inferior growths disappear after draining, and the good
grasses show up and thrive, to be followed in many cases by white
clover if there is a little lime in the soil. Among arable crops the
finer varieties can be grown after draining, while there will be a
stronger and healthier plants of all kinds.

8. Green crops can &< introduced. — On undrained soilsof thestiffer
class root growing cannot be followed, and the land has to be cleaned
of weeds by an occasional bare-fallow. The draining of stiff soils
can be immediately followed by fallow crops, such as mangolds,
swedes, etc., and green-cropping carried out systematically on all but
the heaviest soils. Bare fallowing is not likely to be abandoned, for
several reasons that will be discussed in due course, but draining
makes it more possible to substitute a root crop by making the soil
drier and more friable.

!). Th. ,</' >i' ral climate is improvt 7. — A rise in the temperature of
the soil, a reduction in the amount of moisture evaporated into the
air, a better utilisation of the sun's heat, and a drier soil under foot,
all tend to improve the local climate. The damp raw feeling in the air
at night or in wintertime is partly done away with because the average
temperature of the air is raised, the ground is much more comfortable
to walk over or work upon, while the live stock which graze over it
and lie upon it have their geneial health very much improved.

When the water in the soil is constantly dissolving out small
quantities of themanurial components and carrying them downwards,
it is apparent that the removal of the water through an underground
drain will also mean the carrying away of fertility, and this is what
really does happen.

For many years the drainage water of the manurial plots at
Rothamsted has been tested, and it has been found that certain
proportions of bicarbonates, sulphates, chlorides, and nitrates were
washed out. The chief basic body combined with these was lime, but

70 SOILS: THEIR NATURE AND MANAGEMENT

there were also small quantities of soda, magnesia, potash, and ammonia.
Phosphates escaped in very small quantities. It is the nitric acid of
course that is of most importance among the acids, and the lime
among the bases, and the loss of these must perforce be set down as
a drawback to the benefits of draining.

This loss is of course greatest in heavily manured fields, and it is
also greatest in open soils of little retentive power. It can be
minimised by putting manure on in smaller dressings at more
frequent intervals, and using bulky organic manures, like dung
or compost, on porous soils as much as possible ; while the immediate
planting of one crop (especially a leguminous crop) after the first one
is off helps greatly to " fix " the fertility.

The actual loss in pounds per acre per annum, where ten
inches of rainfall is computed to have escaped by the drains, has
been ascertained on various plots at Rothamsted as follows : —

Lime 98 to 226 lbs. per acre

Magnesia 5 to 20 lbs. per acre
Potash 3 to 12 lbs. per acre.

Of the acids the only one of any importance is nitric acid,
and it is lost at the rate of anything from 8 to 220 lbs. per acre
per annum. These figures vary very much and depend on the
nature of the soil, the kind of crop grown, and the manures
applied, but the point is that there is a loss in this way.

As draining has been systematically practised all over the
country for more than half a century, most of the farms are
now drained, but occasionally we come across a field not done, or
which needs some extra drains to be put in. As already ex-
plained, drains will often do good even where no water ever runs
into the pipes, so that in nine cases out of ten land should be
drained if not already done.

The signs of wetness in land are generally pretty evident. On
pasture there will be a tendency for rushes, sedges, and coarse
" benty " grass to grow, while the ground may be actually swampy
in parts. On arable land the excess of water will be more
apparent ; the water will sit in the furrows, the furrow slice will
be pasty and glistening as it is turned over, and, of course, the
surface will be always wet, for even in the drying winds of
spring wet patches will show up.

Level lands, such as riverside meadows and estuarine deposits,
are more liable to be wet and in greater need of draining than hill-
sides or undulating land. The reason, of course, is that the slope in

THE IMPROVEMENT OF THE SOIL 71

the latter case conduces to the water running away either on the
surface or by slew percolation beneath, while on level land it is
bound to lodge there for want of a natural outlet.

For this very reason land that has been ploughed in high narrow
ridges or stetches before draining may be laid down in " Hats "
afterwards with ordinary open furrows every fifty feet or so. On
wet land, laying it up in narrow stetches of seven feet wide
with a furrow between each was the custom, so as to promote
surface drainage, but the thorough underdrainage of a field renders
this unnecessary, and the soil may be levelled down. The ancient
ridue-and-furrow system still holds in many districts, however,
though the need for it has gone.

II.— Stone Clearing

To some people it may be a surprise to hear that in many districts
one of the most necessary of improvements is to clear the land of
loose stones, when either on the surface or embedded in the soil
near the top. On the newer and clay formations of the south and
east of England the want of stones is one of the drawbacks to
farming, but on many of the older and more indurated rocks,. stones
and boulders are in many cases an absolute nuisance. This is
especially the case in the glaciated area of the country, where
actual boulders may be common.

On the rougher ground on the hills, where pasturage is the only
possible kind of farming, it is not generally necessary to do anything
with the stones and boulders, but wherever the land is required for
arable purposes it must first be cleared of this "rock- wreckage"
before the ordinary implements can be got to work comfortably.

In the olden days, before the manufacture of drain-pipes was
properly developed, a system of drainage with stones was in vogue
in stony districts : the trenches were dug up and down the fields in
the ordinary way, but instead of laying pipe-tiles in the bottom these
were filled a foot deep or so with the stones off the land. In this
way two important methods of improving the soil were carried out
at one operation.

As soon, however, as the plough and the cultivator dip into the
soil, a fresh crop of stones is brought up, which must be removed in
turn, and so the process goes on almost interminably.

In stony districts a favourite way of getting rid of stones was to
build them into the dykes or stone fences. A sleigh was the most

72 SOILS : THEIR NATURE AND MANAGEMENT

convenient carrier for short distances, while for big boulders it was
the most easy vehicle on which to place them.

The work in some cases has been carried on by two generations of
farmers, and is not completed yet, for often a fresh lot of stones
works up to the surface from below. The frost penetrates down
about two feet or so, and heaves up the whole of the soil and subsoil :
when the thaw comes it drops back again, but the soil drops more
than the stones, and so these gradually work upwards to the top.

The expense that has been incurred in some cases is enormous,
and quite equals, or amounts to more than, the cost of thorough
drainage per acre. It is, of course, a job that has been done little by
little, year by year, and therefore sometimes the farmer and his men
have not realised the total cost or the amount of labour entailed. If
a field was "broken in" for the first time on a rough hillside, the
loose surface stones were first gathered up and carted or sleighed off
out of the way somewhere. Then the first ploughing turned up
another lot of stones or rock fragments to be again gathered off.
This process has probably been repeated year after year every time
the field has been worked, until indeed the country people begin to
think that the land "breeds stones."

Of all the geological formations the Boulder Clay is the worst for
stony deposits, for it is full of the wreckage left by the Great Ice Age,
and in many districts cultivation is impossible because there is such
a vast amount of it present that the field could not be made work-
able, though the soil itself may be all right.

It is an "improvement" for the farmer to clear the land in this
way, and it is one that deserves repayment of the " unexhausted
value " to a tenant on quitting his farm, but though a great and
a necessary improvement it has seldom been recognised in this way.
The above operation must not be confounded with the "stone
picking" of the southern counties, where flints are plentiful on the
land. In such districts road metal and similar material are very
scarce, and it is only the Hints picked off the land that can be found
for this purpose, together, perhaps, with Hint gravel found in beds or
layers in various spots. The picking is generally paid for at the
rate of one penny per bushel, and is not an " improvement " to the
land, excepting where the flints are very large. There have been
cases, indeed, where removal of these stones has injured the soil by
making it colder and later, and they have had to be spread back over
the field again.

Of course, the kind of stones that need removal vary according
to the nature of the subjacent rock ; in some cases the stones may be

THE IMPROVEMENT OF THE SOIL 7.)

fragments of limestone, as on the "brashy" soils of the Midlands,
or boulders of granite on the northern hills, but their removal is
necessary for arable work, and is one of the first operations required
in "making" a farm.

III.— Liming

There are very few soils that do not require a dressing of lime
for the purpose of ameliorating their physical condition and of
developing their fertility.

Lime exists in all soils to some extent, but it has a constant
tendency to be washed out or downwards. Even on soils that lie
immediately over the chalk or other limestone formation there may
be a deficiency of it, although the solid rock may be only a few
inches below. This is owing to the fact that water containing
carbonic acid gas has a great solvent power.

In the decaying humus in a soil this gas is evolved, to be absorbed
by the rainwater, and the compound in turn attacks any particles
of limestone or marly matter present, and dissolves and carries it
downwards in solution. In this way a soil is gradually depleted of
the lime which may originally have been in it.

Now, apart from the action of lime as a manure — which will be
treated of in its proper place — it is essential in all soils because of
its value in other ways.

Of all the component parts of a soil the most important one is
lime, for though it is not so necessary as a plant ingredient itself,
yet it is the great controller of fertility in the soil. Wherever lime-
stone predominates in a district we have a " rich " country — both
the live stock and the crops are healthy and thriving, and a want
of lime has a correspondingly disastrous effect.

It has been pointed out by some authorities that the secondary
quality of the crops and stock on the older, rugged, hilly forma-
tions is principally due to the want of lime in the soils and the
parent rocks, and that an artificial application of lime on them is
followed with striking results.

Wherever the soil i^ found to contain less than one per cent,
of lime in its constitution, then a dressing in some form or
another is necessary.

When lime is dissolved out of a soil and washed downwards

it is very often re-deposited at a lower depth as a " pan," by the

■ if the extra carl ionic acid. This must be broken up, of

course, by subsoil work, if possible, and sometimes the turning up

74 SOILS : THEIR NATURE AND MANAGEMENT

of this calcareous deposit is as useful as an actual application of
lime.

The effects of a dressing of lime on the soil are many and
varied. On a sandy soil it has actually a cementing or stiffening
effect, so that there is less of the leaching by passage of water
than before, while the capillarity is increased, and the general
character of the soil improved.

Another of the actions of lime is that on the clay in the soil.
This for want of a better term may be described as a kind of
coagulation or flocculation of the silicate of alumina or the
colloid part that is present there, presumably by driving out the
water of combination in the clay molecules ; in practice it means
that a clay soil that has had a dressing of lime is made more
friable and crumbly, and less sticky when wet, and much more
easily cultivated; the physical characteristics, in short, are im-
proved.

Asa result of this curdling, which appears to be physically the
segregation of the molecules of clay into grains, the capillary power
of the soil is reduced ; less water will soak upwards from below,
thus leaving the soil drier, while the percolating power downwards
will be improved.

The curdling effect of lime on clay can be very well exemplified
by shaking up some muddy water in a glass and allowing it to
settle. The fine particles of clay float in the water and will not
settle, but when some lime water is introduced this precipitates in a
short time, leaving the water clear. The exceptional sparkling clear-
ness of streams off the limestone formations is clue to the lime in
.solution in the water keeping down any tendency to muddiness.

Again, a soil with sufficient humus or organic matter in its
composition is liable to develop various organic acids (such as
humic, geic, crenic, etc.) in the act of decomposition. These are
poisonous to our cultivated farm plants, but a dressing of lime
unites chemically with these and renders them innocuous, if not
useful, and thus in the language of the farm "sweetens" the soil.
Our crops will not thrive in an " acid " soil, but must have it " basic "
or neutral, and lime is the best "base" to use.

In recent times we have found out that much of the fertility
of a soil and its ability to yield crops depend on the presence and
activity of various kinds of microbes. The principal kinds are
those that produce nitric acid from their action on nitrogenous
material. These, however, choke themselves, as it were, with the
acid they secrete unless the is some basic body to take up their

THE IMPKOVEMENT OF THE SOIL 7.')

secretion. Thus lime comes to the rescue, and liming is equivalent
to improving the supply of nitrates in the soil.

Lime, again, unites with some of the double silicates of the
minerals in the soil, and by replacing potash sets it free for food
plants. There is no doubt that it causes many more reactions of a
chemical nature, which all tend to render the "dormant," or insol-
uble, residues of the soil of " active " value to plants, by reactions
which produce soluble compounds.

Another result of liming is the prevention or cure of " finger and
toe" disease in turnips. This is due to infection by a "slime
fungus " which can only thrive in an acid soil. The basic effect of
lime cures this and reduces the attacks of the disease, while the
setting free of some potash. in the soil compounds— as noted before
— is also considered beneficial in this respect.

In the olden days liming a field was a tremendous job, for five
tons per acre of quicklime were commonly applied in some districts,
and the land was sometimes over-limed. The work involved in doing
it was particula' ly troublesome and uncomfortable for both men and
horses, but recent bacteriological science and the application of it in
field practice has shown that a very small dressing (say ten cwt. per
acre) of ground quicklime will give better results, if repeated at a
shorter interval of years.

There are two reasons for this. First, we find that in the old heavy
system the lime " shells" when carted on to the land had to be laid in
heaps and allowed to lie till " slaked " by absorbing moisture from the
atmosphere before spreading. This was a slow process; and some
of the lime, too, absorbed carbonic acid gas from the air and went
back to the same state as the original rock. This meant that the
lime was no longer "quick" (or in the calcic oxide condition), but
really more or less "deadened." Secondly, such a large dose of
the dressing actually poisoned the land, and it was sometimes a year
or two before the soil properly recovered, for over-liming was quite
common. We know now that this " poisoning" was really a case of
killing the soil microbes, and thus stopping the development of
fertility until these had time to again permeate the soil after the
virulence of the lime had abated.

For these reasons, therefore, we have found from repeated actual
experience in recent years that the grinding up of the quicklime
"shells" in a mill at the works and the application of a small
dressing of the same in the "quick" state fulfil all the conditions
of chemical and physical action on the soil, and keep the nitro-
genous microbes in a healthy "basic'' medium.

70 SOILS: THEIR NATURE AND MANAGEMENT

Liming, however, is most efficiently carried out in more ways
than one, and good results are obtained in practical farming by
using other dressings than actual quicklime. To properly understand
this the chemical changes through which "lime "passes should be
studied, and therefore these are set out below :

1. Limestone, chalk, marl — the natural rock form — contain the
Carbonate (CaCo...).

2. When burnt they become the Oxide of Calcium (CaO) or
" lime," " quicklime," " lime shells," etc.

3. The above "slaked" with water or moisture from the air
become the Hydrate of Lime (CaH202).

4. Eventually all forms return to the Carbonate state once more,
but in a finely powdered condition, by absorbing carbonic acid from
the atmosphere.

It will be seen that even when lime is applied to the soil in its
oxide or caustic " quick " condition it eventually returns to its
original dead carbonate state sooner or later, though in a very fine
powder, and, by inference, if the original carbonate rock could be
ground sufficiently fine it would give as good results on the land.
This has been tried with success in actual practice, and the fact
has been established that if limestone or chalk is only ground fine
enough it will be quite efficient for most farm purposes.

That powdered limestone is quite efficient is shown by the fact
that chalk pure and simple is often put on land. It is quarried out
in the wet state and put in heaps on the ground when there is a
chance of frost. This splits the lumps into small fragments which
can then be spread over the soil. There is a danger of the lumps
setting hard, however, and in all the ways of liming land it is desir-
able to have as fine a division of the material as possible.

Gypsum or sulphate of lime is sometimes applied, though not so
often in this country as in the United States. There it is known as
"land-plaster" and much used about stables and cowsheds for
soaking up the liquid manure, and is then employed in dressing the
land.

Besides these methods, liming is sometimes carried out in the
form of marling. Marl is clay containing a large proportion of the
carbonate of calcium intimately mixed with it, and many geological
formations contain such beds. When these were near the surface
and easily accessible it was the custom to dig the marl out and spread
it overthe land. This practice has been discontinued in our days

THE IMPROVEMENT OF THE SOIL 77

because of the cost of labour, but in many districts all over the
country— in Cheshire, for instance -the old marl and clay pits
still remain, forming useful ponds of water in many cases— a relic of
the farming of our forefathers.

Another variety of lime much used near large cities is that known
as gas-lime. In the purification cf lighting-gas from sulphur at the
gasworks quickdime is used, and the latter absorbs the sulphur in the
form of sulphide and sulphite of lime. This bye-product is largely
used by farmers, and on heavy land it is now a valuable source of
lime for the soil. These sulphur compounds gradually become oxidised
into sulphate of lime or gypsum, while there is always some oxide and
carbonate also in the gas-lime heap. When this material is fresh
from the gasworks — especially if of a blue or green colour from
the presence of some ferrocyanide compounds — it is a deadly
poison to plants, and it must be put on in autumn, or otherwise
held over until it has been ameliorated by exposure to the air.

There is a vast difference, which ought to be known to farmers,
between the varieties of lime in the market. A "fat" lime is
one with a large proportion cf pure oxide of calcium, while a
" poor " variety is one with a lot of useless silica, etc., in it.
Thus the limes produced from chalk, mountain, and other lime-
stones are the best, while those from the thin argillaceous de-
posits are much more inferior ton for ton. These thin, poor
"grey" limes are very often the best for builders, because they
set like cement — like the Lias lime, but the other — the " white "
— is the best for the land.

There is an important deposit of the Magnesian Limestone in the
north of England, but it yields lime which is not liked for farming
purposes. The excess of magnesia seems to " burn " the land in a
way that common lime does not.

IY-— Irrigation

In some of the dry and hot countries of the world irrigation, or
watering the land by streams and ditches, is necessary to make crops
grow. There are thousands of square miles of fertile lands in India,
California, and other countries, which lie absolutely barren until
water is brought to them by irrigation. In our country there is
no land barren from want of a copious rainfall, but nevertheless there
are certain districts in which it pays for various reasons to Hood
at certain seasons with river water by way of improving them. The
meadows that lie alongside the brooks and rivers which drain the

78 SOILS : THEIR NATURE AND MANAGEMENT

Downs and Salisbury Plain are examples ; the water is highly
charged with lime, and this flowing over the grass during certain
periods in the winter time helps the growth of the grass and yields
an early spring crop. Another case occurs on the banks of the
Mersey, where the floods carrying silt are allowed to flow over the
meadows for a time, afterwards the sluices are shut and the water
kept out during the rest of the year while the grass grows. It is
only in cases wdiere the water contains some silt or valuable matter
in solution that irrigation is of any use in this country ; the water
alone is not much required in ordinary seasons, while of course the
work can only be carried out conveniently on the level lands ad-
joining a stream.

A special form of irrigation is that known as " warping," practised
on the level land alongside the rivers that run into the Rumber, and
the adjoining districts. In this system the tidal water, carrying
a tremendous lot of silt, is run over the land as deeply as possible
and allowed to deposit its burden. By successive floodings an
actually new soil is deposited on the levels, as deep as desired, and
thus a new bed of alluvium is laid down artificially. When once the
soil is made in this way, however, the water is shut out, and no
further " irrigation " takes place.

At one time in this country there was a great belief in water-
meadows : the level fields near a brook were laid in regular "beds "
with irrigation channels between and the water run on, but these
are mostly disused now, for the simple reason that the application of
plain water to a field was seldom of any value in our moist climate.

On the other hand, irrigation offers a valuable means of disposing
of the sewage of a town, and most towns and even villages are
nowadays provided with sewage farms, unless they are near the sea-
shore and thus can discharge directly into the sea. The modern
treatment of sewage consists in running it through settling tanks,
then in a thin stream over various bodies to expose it to the air so as
to permit the oxidising bacteria to do their work and really " fer-
ment " the sewage material into a soluble and innocuous condition,
though afterwards the effluent water is best run over some land
before it is safely got rid of.

Sewage irrigation for the disposal of the liquid refuse of a town
is generally a big engineering job, which is quite outside the province
of farming in the ordinary sense, but as there is a lot of sewage or
liquid manure to get rid of at every farm, some of the points con-
nected with its disposal should be looked into. Usually this material
is allowed to discharge itself into the nearest ditch, but in view of

THE improvement of the soil to

the future development of sanitary regulations some other way will
have to be found, probably in the near future, for its disposal.

Hitherto the idea has been to collect it in a tank, pump it into a
water cart and spray it over the grass fields. Those who have such
tanks at their homesteads have probably followed this plan for a year
or two and then given it up as an unmitigated nuisance. The labour
difficulty is considerable, for no one cares for such a nasty stinking
job, while as it is impossible to keep out a large share of the rainfall
of the homestead, there may be a tremendous lot of water to deal
with. In time, therefore, the tank becomes merely a settling cess-
pool, and the liquid runs into the nearest ditch.

The future arrangement will be to spread this effluent water
over the surface of the land, somewhere below the homestead, and
there allow it to soak into the ground. It is simply a case of getting
rid of the stuff the best way we can, for when regular irrigation is
tried, it is found that docks, weeds, and coarse grass spring up so
strongly as to spoil the crop.

Loamy and humus soils are the most suitable for irrigation. If
the soil is an open, porous sand, the liquid then percolates down too
rapidly and reaches the drains before it has had time to purify, and

Fie. s. — Catchwork Irrigation, showing Contoub Furrows cut
across the Slope to Catch Downward Flowing Liquid Manure.

the brown juice may reach the ditches just as much as if it were
turned in direct. On the other hand, a clay does not allow of
sufficient percolation, and the water is liable to flood the surface.
With a medium soil, however, there is the proper combination of
porosity and retentiveness for the work, but unfortunately we have
generally to take the soils as we find them.

Where sewage has to be run on to the surface of a field there is
often considerable difficulty and expense in spreading it evenly over
th>: land. The easiest and best way is that known as the catchwork
or contour system. The sewage is laid on the top of a field, and across
the slope small furrows are dug at a perfect level. These form contour
ditches, as it were, and must wind about so as to keep the level, and,

SO SOILS : THEIR NATURE AND MANAGEMENT

at the same time, suit the inequalities of the ground. The liquid
flows over the edge of these and spreads about, and is then caught
by the next furrow, say twenty feet farther down the slope, and
redistributed over the surface again. {See Fig. 8.)

When the object is to get rid of the stuff it is remarkable how
much an acre of suitable soil will absorb. The furrows must be laid
off in two lots, so that they can be worked alternately. The object
is to allow of aeration, for one of the essentials is that the soil must
have time to run itself dry in order to let the air into the pores so
that the "aerobic" microbes may do their work of oxidising and
destroying the faecal matter.

Where sewage irrigation can be carried out for manuring crops
the most suitable crops to grow are Italian ryegrass and Timothy
grass. If it is intended to cut the crop green, then the ryegrass will
be the best, but if it is intended to make hay, the other is better, for
sewage-grown ryegrass makes very inferior hay.

Y«— Manuring

The specific application of manure to individual crops will be
dealt with in a succeeding volume, but it is necessary here to take
up the general question of manuring from the soil point of view.
It was pointed out in a former chapter that every soil was made up
of about twelve chemical bodies, occurring in various proportions in
various soils, and that a fertile soil must contain the most of them.

It is found that all our crops and vegetable productions are com-
posed of exactly the same chemical bodies in various proportions,
with the one notable exception of the metal aluminium or its oxide
alumina— the principal ingredient of the clay in the soil.

Now, every crop that is grown and removed from the field, either
by cutting and harvesting or by feeding live stock, which may in
turn be sold off the farm, takes with it so many pounds per acre (per
annum) of each of those ingredients, and when this process is
repeated year after year for a lifetime or a century, the stock of
those bodies originally in the soil, and forming a large part of its
available material bulk, must be reduced, and eventually a stage
would be reached approaching barrenness or sterility.

In actual farming this stage is never reached, because examination
has shown that ordinary soils in the first six to eight inches in depth
contain fertility enough to grow over a hundred crops, and many
things would happen before the fir.st hundred years would expire.
On the other hand, however, we sometimes meet with cases where

THE IMPROVEMENT OF THE SOIL 81

persistent cropping has so reduced the stock of readily available
ingredients as to seriously interfere with the quantity and quality of
the following crops. In such a case the land has been '"run down,"
and time must be given for it to replenish itself by the production
of some more of its soluble elements by weathering, fallowing,
and cultivation, or by directly applying plant food to it from
outside.

Again, the continuous application year after year of natural and
artificial manures and the consumption on a holding of corn, oil-
cake and other concentrated feeding stuff's gradually increases the
stock of readily available plant food in the soil, and it gets into
good condition with "cumulative fertility."' The crop and stock
carrying power of the land is thus gradually increased as the time
goes on from this " high farming,'' and a farm becomes more valu-
able in consequence.

After half a century of legislation it is now settled that the
unexhausted value of the manures and feeding stuffs belongs to the
man who put it there — the farmer— and an outgoing tenant is
entitled to be paid for it. The fixing of the cash value is a difficult
task, and will vary according to the nature of the soil, stock, and local
customs, but some of the leading agricultural societies have drawn
up scales for the guidance of valuers, and the general consensus of
opinion is that the fertility left behind from such manuring will last
for from two to three years. It will in the case of retentive soils last
much longer, but it is necessary to set a limit for practical use.

As a tenant pays rent for the gradual removal of the inherent
fertility in small annual portions, it follows in equity that he should
not be required to hand over a farm in as good a state manurially as.
he received it, but to counteract this landlords always specify in
their farm agreements that the fertility must be kept up by corre-
sponding dressings of manure, and the leaving tenant can only claim
on the "unexhausted" surplus.

The " valuation " at a change of tenancy in these matters is one
of the most important episodes in a farmer's life, and all the points
connected with it are well worthy of being studied by everyone who
has to do with land.

A close enquiry into the question of manuring has revealed the
fact that out of the dozen bodies in the soil only about seven are
really needed by the plants. Of these there is a superabundance in
the case of three or four, and no amount of excessive and prolonged
in:,' would reduce them to the danger limit. The "exhaustion'
of a soil thus reduces itself to the immoderate removal of about four

82 SOILS : THEIR NATURE AND MANAGEMENT

of the dozen. Those four are nitrogen, phosphoric acid, potash,
and lime. In a few exceptional cases magnesia may also be
reducible, but probably nineteen times out of twenty the first three
only are liable to be depleted. We can see, therefore, that it is
necessary to replace these in some way or another, and the whole
practice of manuring reduces itself — to put the matter generally — to
returning these bodies to the soil. All our commercial varieties of
artificial manures, and even such forms as farmyard manure, are
merely various forms and compounds of- them, and our great and
far-reaching manurial experiments are simply a ringing of the
changes, as it were, on the different kinds of these bodies.

We can even go a long way further than this. In the section on
liming it is shown that lime, marl, and various calcareous compounds
are very little required as direct manures entering into the composi-
tion of a plant, but that they are valuable and necessary as affecting
the soil itself, require to be separately applied, and may be left out
of the category of manures.

Again, potash is required in comparatively few cases. The
lighter soils ore sometimes helped by a dressing of a potash manure ;
in heavy soils, however, not only is it not needed, but a dose often
does harm to the crop, so that this body may also be left out of the
list in the vast majority of cases.

Lastly, we come to the manurial ingredient nitrogen, and its
compound— ammonia, In all " prescriptions " for manures there is
usually an allowance of nitrate of soda or sulphate of ammonia,
bodies useful because of the nitrogen in their composition, while
such manures as guano, farmyard manure, and other " organic "
manures, are valued largely for the nitrogen they contain in
common with the other elements.

The question of nitrogenous manures, however, opens up the
wide subject of the nitrogen in the soil and the renovation of it
by natural means. Within the last generation it has been demon-
strated that the rotting of manure, humus, organic matter, etc.,
is entirely due to the action of microbes, and that, indeed, many of
the natural chemical reactions— or combinations in the soil— are due
to germ life. Plants can only take up their nitrogen from the
outside in the form of nitrates, and the conversion of the nitrogen
in nitrogenous matter into nitrous acid and then into nitric acid is
the life-work of several species of microbes in the soil.

As previously pointed out, the soil must contain alkaline or
basic substances to take up this acid as formed, and thus lime
comes in as the most useful to apply. In this way the nitrogen

THE IMPROVEMENT OF THE SOIL 83

actually in the soil, or in the manurial substances applied to the
soil, is made available for plant food.

But still another discovery has been made in recent times which
has still further altered our ideas regarding nitrogenous manure and
the practical application of it. If the roots of the clover, bean,
pea, or any other leguminous plant are examined, there will be
found nodules or excrescences on them, ranging in size from a
grain of sand up to that of a small pea, according to the kind of
plant.

Research and experiment have shown that these nodules are the
result of the growth of certain microbes inside them. These
microbes extract nitrogen from the air in the soil, combine it
into some compound or other, and then pass it into the roots of
the leguminous plant which forms the "host." This partnership or
interdependence of two plants is called " symbiotism," and in
practice it means that leguminous plants of all kinds do not re-
quire nitrogenous manuring — may indeed be injured by such — but
that a supply of suitable microbes in the soil is more necessary,
and they may require to be added to get good results in growing
leguminous crops.

These facts have now influenced practical farming so far that
'* cultures " of the suitable varieties of microbes are sold com-
mercially, and are applied to the seed — or even direct to the soil— of
the crop about to be grown, and in many cases do more good
than actual manuring.

But the matter does not stop here, for by analogy we might
expect that other plants besides those of the leguminous order would
have microbic helpers as well. That this is so has been proved by
recent experiments, and microscopic bodies have been isolated in a
suitable culture that promotes the growth of cereals in the same
way.

It is therefore now safe to say that all our species of crops will
sooner or later be found to be controlled as regards their growth by
the presence or absence of their own special microbes in the soil.
The use of a "culture" is likely to be more useful on poor soil than
on rich, for the latter is very likely to be well supplied w7ith these
organisms already, but the point is that they act as intermediaries
!)■ tween the plant and its manurial food, and many cases of barren-

- or failure of a crop are now traced to deficiencies in this line.

All this points to the fact that direct nitrogenous manuring is not
really so necessary as we once thought. If leguminous plants are
grown at frequent intervals, and if the soil is inoculated with

Si SOILS: THEIR NATURE AND MANAGEMENT

the proper culture (if the suitable microbes are not present in it)
where poverty or barrenness is apparent, then the nitrogen gets
replenished in a natural way from time to time, and none need be
supplied in a manure excepting in special cases.

Summing up all these facts we arrive at the conclusion that the
food of plants exists in superabundance in most soils, or can be added
by a natural and inexpensive system of replenishment, with the excep-
tion of the one ingredient of phosphoric acid. We are, therefore,
now satisfied that possibly in nine cases out of ten an application of
some one or other of the many forms of phosphates of lime is all that
is required to keep up the fertility of land under a proper system of
cropping. It is the one ingredient that is universally deficient in the
soil, that is not added by the ordinary farmyard dung of the farm in
sufficient quantity, and that cannot be developed or extracted from
anywhere by any system of cropping or treatment, and must be
returned by extraneous manuring.

We must now take a look at the changes produced in the soil by
manuring from other points of view. The most common and natural
manure is farmyard dung, and, of course, as much of it as possible
ought to be made on the farm. When it is necessary to supplement
this, then artificials are cheaper to purchase than dung, unless there
is some special reason for doing otherwise.

One of these special reasons is the value of dung and other bulky
organic manures, like composts, in improving the texture of the soil,
in making it more friable, porous, and open with clay, and " stiffen-
ing" it in the case of sandy soils. It, at the same time, supplies
extra humus, which improves the power of the soil for holding
capillary water, for humus of all the Proximate Constituents is the
best for this purpose, and it does not puddle if worked while wet.

Another good point in favour of dung is that repeated applica-
tions of it tend to darken the colour of the soil and thus raise the
temperature from the extra absorption of the sun's rays, while the
actual fermentation of the dung (microbic life-action) also raises
the temperature temporarily by a few degrees.

As previously stated, when the home supply of dung runs out it
is doubtful if it would not be cheaper to expend money in purchasing
phosphatic manures, but the production of bulky organic manures
can be greatly aided by sowing such crops as mustard, rape, clover,
etc., and ploughing these in. By this means a large bulk of rich
humus is eventually added to the soil when these decay, and thus
the characteristics of the soil are improved very much.

On the lighter classes of soil, or on any soil in the drier districts,

THE IMPROVEMENT OF THE SOIL 85

sheep-folding is largely practised, partly from its convenience in
using up a growing crop and fattening off the sheep, and partly from
its manurial results. The droppings of the animals are evenly and
directly spread on the surface, and when lightly ploughed in add
very much to the organic matter in the soil and to the store of
fertility. Many forage, catch, and root crops are grown for this
purpose, so that the texture, retentiveness, and fertility of the soil
are all improved at the least cost and labour, while the animals are
fed and fatted off as well.

CHAPTER V -THE TILLAGE OF THE SOIL

Tillage is the last subject to be discussed in connection with the
soil. Tillage may be defined as the making of Tilth, and the tillage
operations comprise the regular and entire work of a farm for three-
fourths of the year.

All the other things in connection with the soil — its nature, the
changes that take place in it, its improvement— are auxiliary from a
farming point of view to the "working" of the land.

The varieties of work carried on in tillage operations are many
and varied, but they may be included under (1) Ploughing, (2) Cul-
tivating, (3) Harrowing, and (4) Boiling.

I.— Ploughing

The first operation carried out in the way of ordinary cultivation
is that of ploughing. In a state of nature, land is always in grass or
pasture ; even where a wood or a coppice exists, there will be grass
of some kind growing on the ground, if not too completely smothered
out, and under this condition the removal of the overhead foliage
would soon be followed by a growth of vegetation of some kind on
the ground below. To turn this grass land into tillage the first work
is ploughing, and again, on land already in cultivation, on the removal
of a crop, the preparation for the next crop, in nine cases out of ten,
begins also with ploughing. The technical points connected with
ploughs and ploughing will be discussed later on, and therefore at
this point it is only desirable to investigate the use and effects of
ploughing on the soil. The operation practically amounts to this —
that a wad of soil ten inches wide and seven inches deep is cut off
the edge of the solid land, turned on its edge ovc a third
of a circle, and left partially upside down at an angle of forty-five
degrees. In the old style of ploughing it was desired to turn this
wad or furrow-slice without breaking or cracking it, and to leave the
nicks or seams between successive slices as deep and clean cut as
possible. Nowadays, with the improved "digging" ploughs, the
slice is very much pulverised and broken up, and turned more or
less upside down, with the surface rubbish completely buried. That

THE TILLAGE OF THE SOIL 87

this is the best kind of work to do will be shown immediately. The
objects of ploughing are various.

The principal one is to bury the surface herbage so as to destroy
the wild growths in order that cultivated plants may take their
place. If a fringe of grass or herbage is shown between the furrow-
slices, then the work has not been properly done, and a different
plough or one with a skim-coulter should be used.

The second object is to pulverise the soil. This has only been
recognised within the last generation or so, since the introduction
of the American chilled-steel "digging" breasts on ploughs, for in
the older days, and even yet with backward farmers, the old style
with long sloping breasts was employed, whereby the furrow-slice
was turned over whole. The idea now is to crush the earth on itself
so as to break it up thoroughly, even on stiffish soil, and spread the
crumbly material loosely over.

In other words, the act of ploughing nowadays largely includes
that of cultivating, and the subsequent work of the cultivator and
the harrow- is very much reduced. At the present time complete
inversion of the furrow-slice is desired, as it buries the rubbish best
and leaves the surface in the best friable condition.

By pulverising the soil is opened up to the action of the air,
frost, rain, etc., by which the texture, the physical constituents, the
chemical combinations, and the general conditions of fertility are
improved : the soil, as it were, is helped to put its fertility into an
accessible form.

Another important object of ploughing is to make a good seed-
bed. The native wild plants of the soil will take root and thrive
without any cultivation, but the more delicate cultivated crops
require genial conditions in the germinating and seedling state. It
therefore follows that all the growing grass or rubbish on the surface
should be buried completely, so as to give the new plant a clear
start, while the pulverising and subsequent mellowing of the turned-
up earth gives the seed a better chance to germinate and sprout in a
healthy way.

During the wdiole life of a cultivated plant the roots continue to
grow and ramify through the soil, and thus anything that tends to
make it more tilthy is a direct benefit to them. The wedge-like
power of a growing root is very great, but when the soil is loosened
to begin with it allows of an easier passage, and a more ready
access to the plant food. In this way as much as in any other
tillage stimulates growth.

As the roots of the cultivated crops very often go no deeper than

88 SOILS: THEIR NATURE AND MANAGEMENT

the ploughing, it follows that as a general rule the work should be
done as deeply as possible. The loosening of the soil helps the
surface drainage by letting the rain percolate downwards very
quickly, and thus in a time of extra wet will tend to keep the
surface dry. The depth, in auy case, should be sufficient to prevent
the harrows from tearing up the refuse to the top again, while the
more deeply it is buried the more quickly it will die and decay.

If a "plough-pan " has been formed by the constant passage of
the plough at the same depth year after year, by which a hardened
or pasted-up layer has been formed, then this ought to be broken up
by going a little deeper.

Again, the tendency of some of the elements of fertility is to get
washed downwards by the percolation of the rainwater more than
capillarity can equalise, and so the turning of the lower layer on to
the top aids capillarity and keeps manurial matter near the
surface.

The turning over of a furrow-slice and leaving the top five to
seven inches of soil in a loose, friable condition is equivalent to
forming a " mulch " of it. Gardeners at the beginning of winter very
often put a lot of rough manure round their plants on the surface of
the ground for several reasons : it keeps in the moisture when the
dry weather comes, it keeps the cold of the air from readily pene-
trating downwards, and it keeps in the heat already in the soil. The
bed formed by a succession of furrow-slices all over a ploughed
field acts in exactly the same way, and forms a sort of mulch to the
soil below, and indirectly benefits the plauts.

In order to get the full benefit of the fertilising effects of the
weather, the ploughing should generally be done as early in
autumn as possible. Some farmers, indeed, try to have all their
ordinary ploughing done before Christmas or the New Year time,
and if the soil is of the stiffer class it is very desirable to do so. On
the other hand, on the light sandy varieties the work may be post-
poned with benefit, because the weathering is not so much needed
to make it friable, while the soil is more liable to lose its goodness
by leaching — points which must all be taken into consideration.

In practice, however, the weather usually rules the whole thing.
During hard frost it is impossible to plough, of course, while during
continuous wet weather it is not desirable, even if it were possible,
fur the men and their teams to work outside.

1. Bare-fallowing. — Throughout the southern half of England,
and to a smaller extent in other parts of the British Islands, the
system called Bare-fallowinu is practised. This practically amounts

THE TILLAGE OF THE SOIL 89

to ploughing the land repeatedly and otherwise cultivating it during
the whole of a summer without growing any crop.

There may be from three to five ploughings of the same land
over and over again, with a corresponding number of harrow-
ings, rollings, etc., so that the soil may be gone over from eight to
twelve times during the course of a summer in one way or another
— the last ploughing just finishing up in the autumn in time to put
the ground into shape as regards ridges (or lands) and furrows for an
autumn-sown crop— nearly always wheat.

The principal object of a bare-fallow is to clear the land of weeds :
if the land is put into a "fallow crop" like roots of some sort, it
takes an enormous lot of work in the shape of singling out, weeding,
hand-hoeing, etc., while if the land is kept perfectly bare, then the
work cau be done in a wholesale manner by horse (or other) power,
and the expensive manual labour done away with.

Two conditions, however, are required to make it necessary or
desirable to fallow the land : a dry climate and a stiff soil. If the
climate is wet, bare-fallowing of a stiff soil will not be carried on
satisfactorily ; if the soil is light, bare-fallowing is not so necessary,
because root working is more easily carried out on a ''turnip soil."
These two conditions explain the fact that most of the fallow
farming is confined to the stiffer soils in the southern half of
England.

It may be thought at first sight that ploughing the same land
from three to five times over during the course of a summer is
preposterous, and that the use of a cultivator might do the thing
more economically, but years of experience have shown that on stiff
land the plough does the work best : cultivation only stirs the clods,
while ploughing turns them upside down, pulverises them better, and
kills the weeds much more quickly. If the fallow is very cloddy it is
sometimes impossible to work a cultivator.

Of course, cleaning the soil is not the only object in bare-
fallowing ; the land gets a rest for a year at intervals (every seventh
year in Mosaic times), and the nitrification and weathering allow of
an accumulation of ready fertility which prepares the soil for an
extra good crop to follow. Again, the exceptional amount of stirring
and mixing of the soil that takes place causes a greater amount of
this fertility to be set free by the stimulation of the various chemical
reactions and the modification of the texture of the soil. The total
result, therefore, is to have the soil thoroughly cleaned of weeds, to
have it mellowed and improved in texture, to give it a rest, and
to allow of the accumulation of the soluble fertile ingredients.

90 SOILS: THEIR NATURE AND MANAGEMENT

A field thus treated will yield better and cleaner crops for
several years afterwards, and pay well for the work. The intro-
duction of fallow crops more than a century ago, in the shape of
mangolds, swedes, turnips, etc., tended to largely reduce the practice
of bare-fallowing, and it is now only followed as a regular
practice on the heavier soils in the drier districts, but in these cases
it is a commendable practice.

So much good is done to the soil by bare-fallowing, that many
years ago, a clergyman (the Rev. Mr. Smith) at Lois Weedon, in
Northamptonshire, inaugurated a system of alternate fallow and
wheat cropping, which he carried on for over thirty years with
perfect success. The land was laid up into the usual narrow
"stetches," and each alternate one was summer-fallowed, and the
other alternate ones cropped with wheat— changing about each year.
Thus, practically half the field only was in wheat and half in fallow,
yet the wheat yield totalled over the whole better than the usual
crop of the neighbourhood. A system like this of course, depended
wholly on the " inherent capability " of the soil, and it could have
only succeeded where the soil was stiffish and of a fertile kind —
for the system would have failed on a light, poor soil or in a wet
district ; but the point is, that a perfect and continuous bare-
fallowing was the basis of the whole practice.

It must be emphasised that there is another reason why fallow-
ing succeeds best in a dry district ; there is no waste of fertility
from leaching. As already shown, a growing crop helps very
much to retain plant food in the soil, and if fallowing— which
means complete killing out of all vegetation — is followed when
there is much rain then there is an extra waste of this plant food.
On the other hand, a bare-fallow is usually sown with winter wheat,
so that there is a crop ready to absorb the nitrates and other
manurial bodies before the rains of winter come.

2. Subsoiling — This process is quite a different matter from
ordinary ploughing, and on certain soils may do a vast amount
of good. It may be done by having one plough of a special kind
to follow another in the furrow made by the first, and thus stir
up the bottom several inches down without bringing it up to the
top.

Another method is to have a large tine fastened on to the beam
of the ordinary plough in front of the mouldboard (see Fig. 9), so
that the bottom of the furrow is ripped up as deeply as possible,
and then the new furrow-slice turned over on the top of it. The
steam cultivator, again, may be set deep enough so as to penetrate

THE TILLAGE OF THE SOIL

ill

through the soil into the subsoil, and thus break it open. The
point to be aimed at is to simply stir up and pulverise the subsoil
and leave it below the soil in the original relative positions, so that
there is no admixture or bringing the possibly poisonous stuff to the
"top. The benefit to the land is due to the loosening of the subsoil
so as to let the water down more freely, and also the roots of the
crop- if they find it suitable ; to the breaking up of the " pan " if
one has formed ; and to the aeration and ventilation of the whole
body, whereby oxidation and other improving chemical reactions
are promoted.

The poisonous bodies likely to be present are such compounds

^

Fig. 9. — Ploi'Oh, with Subsoiler attached, by which the Bottom of
the Furrow is Ripped up and immediately Covered by the
Furrow-slice.

as sulphide of iron, sulphuretted hydrogen, humic and other
earthy acids. These are inimical to plant life until oxidised or
otherwise modified, and if too much of the subsoil containing
these is brought to the top it may take years to convert it into
soil good enough for crops.

Subsoiling in this way never does any harm, as deep ploughing
might do, but on the other hand it may do no appreciable good.
Where the soil is gravelly or sandy, or even loamy, it is very likely
that the deeper soil and subsoil will already be so open and porous
in their texture that to stir them up would only be throwing away
money.

On the heavier and stiffer class 0f soils, however, the operation is
of the greatest value, more particularly in assisting the downward
percolation of water, and thus preventing the waterlogging and

92 SOILS: TEEIK NATURE AND MANAGEMENT

.souring of the land in wet weather, at the same time assisting
the general farming of it.

Subsoiling, however, is very expensive work. The ordinary-
plough with a subsoiler attached will take four horses and two men
to handle it, and not go very deep at that ; where one plough is
followed by another in the same furrow (known as " trench-
ploughing'") it may take six or seven horses and three men, and the
field will be gone over very slowly ; while with the steam cultivator
there has never been much of a success made in practice, probably
because the drivers were too afraid of bursting their engines by
letting the tines go deep enough into the ground.

It is perhaps in the matter of assisting the downward percolation
of the water that the deepening of the staple and subsoil does most
good. On the stiller class of soils in wet weather the soil very soon
fills up with water which cannot get downwards, and it not only
kills any crop growing there but begins to wash over the surface,
finding its way into the nearest waterfurrow and ditch, and carrying
with it much of the soluble fertility of the soil or of any manure
present.

Now, the stirring of the deeper layers has the effect of aiding the
downward passage of the water to the drains below, and thus while
leaving the top dry and open keeps the fertility in the soil.

II.— Cultivating

Cultivation is a general term applied to many different kinds of
work, all of which have for their object the pulverising of the soil,
the mixing up of the ingredients, the opening up of the whole to the
action of the w7eather, the eradication of weeds, and, generally, the
melioration of the soil to make it more suitable for plant growth.
It usually follows ploughing, and in some form or another constitutes
a large share of the tillage which goes to make tilth.

Work of this nature is done with a special implement, called a
cultivator or grubber. It is pretty well conceded now thai" rigid
tines on these cultivators, with spring sockets or settings, is the
best form. The action of the spring yields a little to obstructions,
allows of a certain amount of vibration or play of the tine, and
thus improves the work and enables the shares, or cutting parts, to
keep clearer of weeds as they move along. (.sVr Fig. 10.)

The work of the cultivator does not always follow the plough,
however, for in districts where steam cultivation is common, this

THE TILLAGE OF THE SOIL

93

work is usually carried out on the untouched stubble land, and in
dry weather when the ordinary plough probably could not touch
it. Cultivating with the huge steam implement after harvest, or
after a crop has been taken off in summer time, is one of the most
efficient ways of breaking up the soil, mixing it, rooting up the
weeds, and killing all the surface rubbish, so that a "half-fallow "

Fig. 10.— Royal Agricultural Society's First Prize Cultivator, a.
Two-horse size. b. Vibrating Action oj? Tine with Spring
Setting.

made this way is a very good thing, and allows of the growth
of a crop of some sort during the previous part of the same
summer.

It is, indeed, with the cultivator that steam-power has been most
successful. The natural depth of the soil limits the depth of

!H SOILS: THEIR NATURE AND MANAGEMENT

ploughing to, say, seven inches, and the giant strength of steam is
wasted in doing work that ordinary horse-power can accomplish
more cheaply. On the other hand, as cultivation consists in only
ripping up the soil and stirring it, one may go as deep as possible
with the greatest benefit ; indeed, the trouble in practical work is
that the workmen will not go deep enough. They are generally paid
by the acre, and prefer, if not looked after, to skim along at the
ordinary plough-depth, while when the grubber is sunk into the solid
subsoil it often stops the engines.

There is no doubt that if the steam-power is sufficiently strong,
and the tines set deep enough, this would be the best way to
break up the soil t: pan," stir up the subsoil, and loosen and mix
the bulk in a way that would be a permanent improvement, besides
doing the ordinary fallowing work.

The ordinary cultivator is an implement drawn by three or four
horses, and taking a width of from five to seven feet at a time —
allowing three tines or teeth to every horse. The depth accomplished
is never beyond plough depth, or say six inches, and is generally
less excepting on the lighter soils.

Indeed, where the soil has been ploughed or stirred once to a good
depth there is less necessity for going deep with the cultivator after-
wards, and sometimes three to four inches are quite sufficient. A good
rule is to plough deeply enough to completely bury the surface rubbish
and then cultivate lightly enough so as not to bring the rubbish to
the top again, unless it is intended to make a regular summer fallow.
Scarifying, that is cultivating only two to three inches deep in dry
weather, increases the mulching power of the soil, and preserves
more of the capillary water below from evaporation.

A cultivator is a large-tined implement, differing chiefly in size
from a harrow. There is an endless variety of forms, and between
these two extremes there are any amount of intermediate kinds,
some of which will be examined when we discuss the Equipment of
the Farm.

Cultivation on the smallest scale is hand-hoeing. In a garden,
or where small culture is followed, the soil will first be turned over
with a spade— work which the "digging-plough" imitates— and then
the cultivation afterwards is done by hand-hoe. On a slightly
larger scale we have the horse-hoe, used between the rows of plants,
with the hand-tool as an adjunct.

Hand-hoeing is of course one of the most expensive labour items
on the farm, but we cannot get on without it. In the cultivation of
root crops — which require the plants to be " singled " out separately

THE TILLAGE OF THE SOIL 95

— the hand-hoe is necessary, and indeed the growth of all our farm
crops in regular rows necessitates cleaning and surface cultivating
by this hand implement.

Cultivation in the proper sense of the term cannot, of course, be
carried on in the winter time— only ploughing — and the work done in
the other seasons depends very much on circumstances. Spring
cultivation will do very well in districts where the rainfall is plenti-
ful, but where the summers are dry it wastes the moisture to stir up
the soil deeply in the drying spring winds, and, therefore, in such
cases autumn cultivation must be carried on : the land ploughed and
worked about after harvest as much as possible, and then ridged up
or left rough for the winter.

III.— Harrowing

The harrow is simply a surface cultivator. The plough
first moves the soil in more or less solid pieces, the cultivator
breaks these up, mixes and stirs them about, and the harrow com-
pletes the work by comminuting and levelling the surface. The
original and primary use of the harrow was, of course, to simply
cover in the seed. The seed was scattered by hand on the top of the
ploughed or cultivated land, and the harrow | the branch of a tree in
ancient times) was dragged over it to level down the rough parts and
cover the seed.

Nowadays there is every conceivable form of harrow, and some
implements, as before stated, are intermediates between a harrow and
cultivator, while every kind of cultivating work can be done by
them.

The typical harrow is used simply for surface cultivation. It
breaks up the lumps on the surface, levels them down, and leaves
the soil comparatively smooth and even, and puts the finishing
touches to the cultivation, as it were. As with the cultivator, the
best modern varieties are the " spring-tooth " forms with adjusting
handles. The spring-tooth is, of course, made of steel, and in work
it dances and vibrates about in a way that thoroughly shakes up the
soil and prevents the clogging of its own teeth with rubbish. The
clogging of the harrow-teeth is one of the drawbacks of working
on the soil if wet or weedy, and the modern " spring-tooth" form
obviates this difficulty.

3 line harrows are really cultivators, such as the "drag" harrow,
while even some of those that do not go quite so far in this line

96 SOILS : THEIR NATURE AND MANAGEMENT

are more than mere surface smoothers. Thus, the disc-harrow, the
acme-harrow, the Norwegian harrow, and the "duck-foot" harrow all
do more than ordinary work, and really stir and mix the top layer
from the top in contra-distinction to the cultivator, which more or
less rips up from below. It is in regard to this difference of working
that the chief distinction between a cultivator and a harrow lies.
The tine or tooth of a cultivator is always curved forward, so that
the point or share on it grubs up from below, whereas, a harrow-tine
enters the soil more or less perpendicularly and simply scratches
or stirs from the top.

When the digging plough with modern pulverising mould-board
is at work, the soil is often so crumbled and level-spread that further
work is unnecessary, and the seed may be drilled in on the same
without any additional work, excepting one stroke or so just to
smooth off for a finish.

As a rule, a good deal of harrowing is desirable. It makes the
surface finer and better mixed ; it kills any seedling weeds by
uprooting them ; it breaks the surface cap which is apt to set after
heavy rain ; if not overdone it covers in the seed better ; and it
forms a fine surface mulch in dry weather.

Like many other things there is a time to do it and a time to
leave off. There is no use in trying it when the land is wet — if it is
stiffish soil at least— for it would only puddle the soil to do so, and the
horses' feet would tend to poach it. Then, as harrowing is generally
done in connection with ploughing, cultivating, or seeding, it
must be done when these other processes are being carried out
properly.

IV.- Rolling

At its first development Rolling consisted of simply smoothing the
ground. No matter how well the state of tilth of the soil, the harrow
leaves a certain amount of roughness behind it, while on stony
or gravelly soil a lot of stones will be left loose upon the top.
Rolling flattens these all down, and leaves the field well suited to the
work of reaping or other harvesting of the crops.

In our time, however, it has been found that certain other results
are obtained by pressing the soil. While a good state of tilth is
desirable it is quite possible to have the particles of soil too loose and
open, and a certain amount of firmness is necessary to get the seed
into proper contact with the particles and moisture of the soil and
the plant food.

THE TILLAGE OF THE SOIL 97

Furthermore, in a dry climate, the touching of the particles
promotes capillarity, and thus the crop may be helped to sustain
itself through a drought with the moisture that rises to the roots
from below, though the top layer may be absolutely dry.

But rolling has certain other physical influences on the soil.
While promoting the flow of capillary water upwards, it also at the
same time promotes evaporation, so that while the top soil has more
water the under soil as a whole is iosing a considerable quantity.
For germinating purposes, however, this is what is desired. It
may be often noticed that seeds of all kinds sprout most quickly
on head-lands and where the ground has been trampled. This
is due to the fact that the moisture below7 comes more readily
to the top where the ground has been pressed, and thus the seed
comes into closer and quicker contact with the damp and sprouts
more promptly.

For this reason also, small seeds, such as grasses and clovers, are
often sown on a rolled surface, and then harrowed in afterwards :
the soil is broken finer and closes in better about them.

The smoothing of the top of the soil by rolling promotes wind
velocity ; the wind next the ground may go at double the speed on a
smooth field to what it will on a cloddy or rough one, and thus the
amount of evaporation is still further increased.

On the soil temperature the rolling of the land has a marked
effect, at any rate in the early stages after the work is done. At one
and a half inches below the surface it may be 10° Fah. warmer than
in the same soil not rolled, and at three inches it has been found G^o0
higher. This is pretty much due to the superior conductive power
of the firm soil for the sun's heat as against the loose unrolled part.
The loose soil acts as a blanket to keep out the heat, but conversely
it tends to retain the heat that is already in the soil, and thus at
night or during cloudy weather when there is no sunshine the
unrolled land may be best. On an average, however, rolled land is
about 3° Fah. warmer than when left loose and rough.

The pressure of the roller is felt from five inches to twenty-four
inches downwards, according to the weight of the roller and the
nature and state of the soil. A heavy roller should be used— any
weight from ten to fifteen cwt. is desirable — and the work with it
should not be too quickly hurried over, so as to give time for the
pressure to act. The barrel of the implement should be of large
diameter — thirty to thirty-six inches — so as to make the draught
easy in proportion to the weight.

It is obvious, therefore, that the benefits to be obtained by

H

98 SOILS : THEIR NATURE AND MANAGEMENT

rolling are discounted by certain disadvantages, and the point
arises if it were not possible to partly counteract those disadvantages.
In a dry season the waste of water from a smooth surface may be
enormous, and therefore, after rolling, great advantage is obtained
by running a light harrow over the ground in order to again ruffle
up the surface. By this means the consolidation of the lower layers
is obtained for germination and water-supply purposes, while the
upper layer forms a loose cover to keep the moisture in.

Gardeners tread down their seed beds very firmly, but take care
to loosen and crumble the top afterwards, and to keep it so by
subsequently hoeing and raking. We want to apply the same
principles to field-work. So much is this the case, that in the dry
southern counties rolling of the root crops is very thoroughly and
repeatedly done in order to bring the moisture from below and to get
the soil close in to the seed or rootlets ; afterwards, there is horse
and hand hoeing in abundance to keep the top loose while killing off
the weeds. Land should, of course, be rolled when dry to prevent
pasting up of the pores from the compression, but there is little
fear of the work being done while wet, because the roller would clog
up in the first few yards if the ground is the least damp on the
surface.

A student may have a difficulty in understanding how it is that
we use all manner of implements to stir up and loosen the particles
of the soil, and do certain other things — such as dressing with a lot
of dung— to make it more friable, and then deliberately go and
squeeze it down tight again. The explanation is that when the soil
has been ripped up by the cultivating implements it is apt to be left
too full of actual fissures and air spaces, and the particles m tst
be made to touch again, but the soil once having been separated
no amount of rolling will bring about entire cohesion.

The question of the use of smooth versus ribbed or toothed rollers
does not seem to have been thrashed out as well as we would like.
All the facts before stated apply to flat or smooth rollers, but in
England, at least, the use of various other kinds is common.
With ribbed rollers there is a line of compression and a line of
loose soil left in alternate three-inch strips made by the flutings of
the ribs. It follows, therefore, that many of the disadvantages from
wind velocity, want of a mulch, and so on are obviated by the use of
rollers of this description. This is borne out in practice by the
fact that such rollers are mostly used in the drier districts of
England.

The method and results of using a roller are indeed very much

THE TILLAGE OF THE SOIL 99

controlled by the rainfall. In the wet northern and western
districts, rolling once with a smooth roller is done for the purpose
only of smoothing the land and pressing stcnes and clods down so
that with (say) corn crops the afterwork may be expedited, and no
question of capillarity, evaporation, germination, etc., ever enters a
farmer's head : there is sufficient moisture and to spare. But in the
southern and eastern counties, where rain is scarce, everything has to
be done to conserve the moisture in the soil, and the rolling
done and the kind of roller used should be the best for this
purpose.

Conclusion

We have now seen in a general way, without going into very
much detail, what a complicated thing the soil is, how the sur-
roundings of a farm influence it, and how we may improve and
cultivate it.

The study of the soil has been vastly extended during the last
ten years or so, and we understand many things now that were a
puzzle to our fathers. These results of recent research are being
applied to the practical management of the soil in a way undreamt
of a few years ago. As time goes on this will be done to a still
greater degree, and farmers will more and more utilise the discoveries
of science to the working of the land.

A few words may be given, by way of conclusion, in the shape of
advice to a farmer inspecting farms as a preliminary to renting one.
A sitting tenant has probably found out to his cost by experience all
the capabilities and drawbacks of his farm, but a man going into a
new district cm find out many things in advance if he knows
what to look for, and uses his eyes.

A slight knowledge of geology will tell him if he is likely to find
sand, loam, clay, marl, or alluvium as the prevailing soil, or if the
farm is on an uncultivatable hill A look at the predominating trees
will corroborate his ideas of the nature of the soil (and subsoil also) :
if the trees stand plumb it is not a stormy district, but if they grow
lopsided then the corn crops will get blown over also and "lodged "
by the strong winds before harvest.

If there are large woods adjacent, then game and other vermin
are liable to be too plentiful; only just enough trees for shelter is
more desirable.

Other things to note are the condition, texture, depth, colour,
etc., of the soil, while if the inspection is made when the crops are

KM) SOILS: THEIR NATURE AND MANAGEMENT

growing the best indication of its capabilities is obtained. The
efficiency of the drainage, the water supply, the exposure and
shelter of the farm and homestead, the steepness or levelness of the
fields, the prevailing weeds among the crops, and so on, with a host
of other points raised in the previous pages, are matters to be
seen to.

There are many things that go to influence the value of a farm
besides the characteristics of the soil — such as buildings, markets,
labour-supply, etc., which we shall discuss in the succeeding volumes
of this series — but the more notice taken of the above points, and
others of the same nature, the truer notion will a farmer get of the
value of the farm under inspection, and thus save himself much
possible expense and loss in the future.

INDEX

Absorption, Soil, 32

Acid, Citric, test, 15

Action, Chemical, 6

— of frost, 5, 29

of plants, G

of water, 3

Air, Temperature of, 51

Alkali lands, 42

Alluvium. Texture and Composition

of. 22
Altitude, Effect of, 51
Alumina, 13

■ silicate, 3

Analysis of soil, 13
Archaean rock, 18
Aspect, Effects of, 57
Augite, Composition of, 2

Bacilli, Action of, 8

Bacteria. Nitrifying, 37

Bad land. Indications of, 25

Bagshot Sands, 21

Bare -fallowing, Objects of, 88

Barrenness from exhaustion, 80

Blacklands, 20, 22

Boulder clay. 21

Brash, 9, 20

Brick Earth, 21

Calcite, 2

Cambrian rocks, 18
Capillarity, 31, 40
Carbonaceous matter, 12
Carbonate of lime, 2, 19
Carbonate of magnesia, 19
Catch-crops, 33, 85
Catchwork irrigation, 79
Chalk, 20
Chemical action, 6

composition, 12

Citric acid test, 15

Classes of soil, 16
Classification of soil, 15
Clay, 3, 10, 20

— particles, 11
Clearing stones, 71
Climate, 52, 69
Coal Measures, 19
Cold soils, 43
Colloid silicate, 3, 30
Colour of soils, 36, 43
Composition of soils, 8, 12
Constituents, Rock, 2

— , Proximate, 10
Contour, Features of, 59
Cultivation, 92, 9
Cultivator, 93
Cultures, Microbe, 83
Cumulative fertility, 81
Curdling of soil, 29, 30, 74

Depth of soil, 33
Digging plough, 86
Distribution of soils, 17
Downs, Soil of, 21
Drag harrow, 95
Draining, 66
Drains, Action of, 41
Drift maps, 17
Dunbar soil, 18, 22

Earth, 1

— Brick, 21
Earthworms, Action of, 7
Elementary bodies, 13
Evaporation, 42

Fallow, Bare, 88

— — Crop, 89

Farms, Hints on inspecting, 17, 24,

25, 50, 57, 62, 99
Felspar, 2

102

INDEX

Ferric oxide, 14
Fertility, 23

— , Cumulative, 24]

— , Indications of, 24

— , Inherent, 24, 90
Finger-and-toe disease, 75
Forage, 85
Formation of soil, 3
Formations, Rock, 17
Frost, Action of, 5, 20

CSas lime as manure, 77

Gault clay, 20

Geography, Physical, 50

Geological Data, 17. 64

Glacial Drift, 21

Good land. Indications of, 24

Granite, 17

Gravel, 11

Gravity, Specific, 34

Great Ice Age, 3

Great Oolite, 20

Green crops, 69

manure, 29

- Sand, 20
Gritstone, 19
Grubber, 92

Gulf Stream, 53, 61
Gypsum, 76

Harrow, 95

Harrowing, 95

Heavy soil, 30

Hints on inspecting farms, 17. 24,

25, 50, 57, 62, 99
Hoeing, 94
Hornblende, 2
Hot soils, 43
Humus, 10, 11, 12, 36

Igneous Rocks, 18
Indications of bad land, 24

— of good land, 25
Improvements, 66
Inherent fertility, 24, 90

Inorganic part of soil, 12
Insoluble part of soil, 15
Iron oxide, 14
Iron soil-pan, 10, 91
- sulphide, 11, 36
Irrigation, 77
Isothermals, 50

Kaolinite, 3
Kinds of soil.

16

Land, Indications of bad, 24

, Indications of good, 25

Latitude, Effect of, 50
Layers in soil, 8
Lias clay, 20

Lichens, Disintegrating power of, 6
Light soil, 30
Lime, 10, 11, 14, 60
— carbonate, 2. 19
Lime pan, 10, 73
Limestone, 19

— , Magnesian, 19, 7

— , Mountain, 19
Liming, 73, 76
Lois Weedon system, 90
London clay, 21
Loss3s in soils, 7<»

Magnesia, 14

Magnesian limestone, 19, 77

Manure, Nitrogenous, 82

Manuring, 68, 80

Maps, " Drift " and " Solid "

Strata, 17
Marl, 11
Marling, 2
Mica, 2

Microbes, Action of, 7, 83
Micrococci, 8
Millstone Grit, 19
Minerals, Kinds of, 2
Moisture, 39
Mountain Limestone, 19
Mosses, Disintegrating power of, 0

INDEX

103

Natural vegetation, 02
New Red Sandstone. 19
Nitrification, 7. 37
Nitrifying bacteria, 37
Nitrogen, 14
Nitrogenous manure. *4

Odour of soib, 37
Old Red Sandstone, In
OoSte, Great, 20
Organic part of soil, 12
( ►rigin of soil, 1
Oxford Clay, 20
Oxidation. 37
( »\ide of iron, 14

Pan, Iron. 10, 91

, Lime, 10, 73

- . Plough, 10, 88
Particles of soil. 11. 20
Peat, 22

Percolation, 39, 68
Phosphoric acid, 14. 85
Physical geography. 50
Physics of soil, 26
Picking stones, 72
Plant action. (>
Ploughing, 86
Plough pan, 10, 88
Porosity, 28

l, 14, 82
Primary Strata. 1
Proximate Constituents, 10

Quartz, 2
Quartz Hour. 27
Quaternary Formation, 21
Quicklime, 7

Rainfall, 53

F\ain wash, •">. 'is
Recent formations, 22
Retentiveness of soil, 31
Rib-roller, 98

Rock constituents, 2

weathering. 3

Rocks, 2, 9
Rollers. 98
Rolling, 96

-. Effect on temperature of, 97

Roothings The, 21

Roots, Effect of draining on, 67

Rubble. 9

Sand, 10

Sandstone. New Red, 19

. Old Red. 18

Sea, Influence of, 61

Secondary Formations, 19

Section of soil.

Seed bed, 48, 8

Shelter. 56

Silicate of alumina, 3

Silurian rocks, 18

Soil, Chemical action in,

Definition of, 1

Depth of, 33

Earthworms' action on, 7

Formation of, 3

Frost action on, 5

Inorganic part of, 12

Insoluble part of, 15

Layers in, 8

Microbes in, 7, 38

Organic part of, 12

Origin of, 1
particles, 11, 26

Physics of, 26

Plant action on, 5

Section of, 9

Soluble part of, 15

Structure of, 8

Ventilation of, .".7

washings. 5
Soil-;. Absorptive power of, 32

Analysis of, 13

Brash, 9

Chemical composition of, 12

Classes of. It)

< I i -ification of, 15

104

INDEX

30,
17

G6

Soils. Cold, 43

Colour of, 36, 43

Composition of, 8, 12

Constituents of, 10

Cultures for, 83

Curdling of, 29, 3

Distribution of,

Earth, 1

Fertility of, 23

Hot, 43

Improvement of,

in situ, 4

Kinds of, 16

Light, 30

Losses in, 70

Moisture in, 39

Odours of, 37

Pans in, 10, 73, 88, 91

Porosity of, 28

Proximate Constituents of, 10

Retentiveness of, 31

Specific gravity of, 34

Temperature of, 42, 46, 67, 97

Tenacity of, 30, 67

Texture of, 29

Transported, 4

Weights of, 34
Solid strata map, 17
Soluble ingredients, 15
Specific gravity of soils, 34
Springs, 40
Stones, 10, 11
Stone clearing, 71

picking, 72

Strata, 17
Structure of soil, 8

Subsoil, Position of, 8
Subsoiling, 90
Subsoil plough, 91
Sulphide of iron, 11, 36
Sulphur in soils, 14

Temperature of air, 5

- of soil, 42, 46, 67, 97
Tenacity of soil, 30, 67
Tertiary formations, 21
Texture of soil, 29
Tillage, 46, 86
Tilth, 38, 47
Transported soils, 4
Trap rock, 18
Trees, Comparative values of, 64

Valuations, 81
Vegetation, Natural, 62
Ventilation of soil, 37

Warp land, 4, 78

Washings, Soil, 5

Water, Action of, 3
— , Evaporation of, 42
— , Percolation of, 39, 68

Water supply, 53, 55

Water-table, 39

Weald clay, 20

Weathering, 3

Weight of soil, 34

Wetness of soil, 70

Wolds, 20

Zeolites, 32

PitiNTED hy Casseli and Co., Ltd., La Belle Savvage, London, E.C.

•••rvijujr ui uinisn ^ouimDia Library

DUE DATE

APP 10 '

APR 1 0 RECC

ET-6

FORESTRY

JUL 2 5 1988

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