THE SPIRIT OF THE SOIL
FIG. I
The Grevilleas shown above were treated, the plant on the left with
complete chemical manure and the plant on the right with humogen
and ordinary soil. J he freedom of the side growths, apart from
remafkabl impr°Ved £rowth of the humogen -treated plant, is
(The Royal Gardens, Kew.)
Frontispiece
THE
SPIRIT OF THE SOIL
OR
AN ACCOUNT OF NITROGEN FIXATION
IN THE SOIL BY BACTERIA AND OF
THE PRODUCTION OF AUXIMONES IN
BACTERIZED PEAT
BY
GORDON D. KNOX
AUTHOR OF
"ALL ABOUT ENGINEERING," "ALL ABOUT ELECTRICITY," AND "ENGINEERING"
WITH A FOREWORD
BY
PROFESSOR W. B. BOTTOMLEY
' Semina vidi equidem multos medicare serentes
Et nitro prius et nigra perfundere amurca
Grandior ut fetus siliquis fallacibus esset."
VIRGIL: Georgics, 1, 193-195
S^CpND .IMPRESSION, .
NEW YORK
FREDERICK A. STOKES COMPANY
PUBLISHERS
Printed in Great Britain
FOREWORD
THE interest aroused in bacterized peat during the
last two years is sufficient reason for the publication
of a popular book dealing with the recent researches
on humus formation, nitrogen-fixation, and acces-
sory plant-food bodies (auximones) . Owing to pres-
sure of other duties I had neither time nor oppor-
tunity to undertake the work myself, but in leaving
this task to my friend Mr. Knox I had every confi-
dence that the subject would neither lose in accuracy
of fact nor in the interest of its presentation.
Mr. Knox's literary ability, combined with his
scientific training, render him peculiarly well fitted
to write a book popular in style, yet without sacri-
ficing the scientific side of the subject. Mr. Knox
has submitted to me the manuscripts of the various
chapters, and it is a pleasure for me to be able to
say, at his request, that I can take full responsibility
for all the results which he has described.
I can confidently recommend Mr. Knox's book as
an accurate and popular exposition of a new develop-
ment in agriculture and horticulture which may have
an important bearing on the national food-supply.
W. B. BOTTOMLEY.
BOTANICAL LABORATORIES,
UNIVERSITY OF LONDON,
KING.'S COLLEGE.
3593^7
PREFACE
THE present volume is the outcome of the keen
personal interest that I have taken for some eight
years in the work on nitrogen-fixing organisms that
has been in progress in Professor Bottomley's
Laboratory at King's College. It would have been
difficult for me to write of the subject without en-
thusiasm. To many botanists the beauty of plant
life to some extent masks the supreme mysteries of
the vegetable world. Few conceptions are grander
than the wonderful storage system which from the
beginning of biological time has enabled plant life
to seize and hold in the tissues some of the steady
stream of energy that flows continually from sun to
earth, avoiding waste, steadily purifying the air, and
rendering its composition constant. That is an old
conception well established and commonly known.
To-day, however, we are watching the growth of a
new conception. Just as the plants have been
steadily storing the energy that is required for the
support of animal life, and making existence possible
for them, so the bacteria in the soil have been
supplying the plants with the essential substances
that they require for their more limited activities.
Nitrogen as such is valueless to plants. Were it not
for the work of the bacteria in the soil no plant could
viii PREFACE
win a livelihood, for it is only when the abundant
nitrogen in the air and in decaying organisms has
been combined into suitable chemical compounds
that it becomes available as a plant food. The work
of Professor Bottomley has been concerned ex-
clusively with the activities of these organisms, and
his object has been to find a means for giving them
an environment in which they can freely develop.
His aim has been in fact to do for the bacteria the
same service that the gardener and farmer perform
for the plants that they cultivate. Husbandry is
the oldest of the arts and sciences, bacteriology the
youngest. In this book I have attempted to indicate
some of the results that will certainly follow from
soil inoculation. I am not suggesting that Pro-
fessor Bottomley has found the whole truth, that
later workers will not achieve the results that he can
claim by more suitable methods. I think, however,
that the evidence collected in the following pages
will convince the reader that a notable advance has
been made in horticulture, and that a new discovery
of momentous consequence has been made in the
accessory food bodies or auximones, a discovery
that will complete and round off the corresponding
discovery of vitamines and their relation to the
health and growth of animals. Lastly, I have pre-
pared the book in the hope that farmers and gar-
deners will, as they alone are able to do, carry these
experiments into the wider field of everyday life.
Farming and gardening are arts requiring expert
knowledge. It is only reasonable to suppose that
laws and conditions, comparable with those governing-
PREFACE ix
the growth of plants, maintain for bacteria. The
work of Professor Bottomley opens up an oppor-
tunity for every gardener and for every farmer to
undertake important scientific work, and at the
same time almost certainly to increase very con-
siderably the yield from his land. Such work is of
the very first national importance and of world-wide
interest. It is certain that one of the most
important factors in the fertility of all land is the
nature of the bacteria in the soil. In every depart-
ment of life man, by assisting Nature, has been
generously rewarded. The science of bacteriology
both in medicine and in the arts has very richly
repaid the labour spent on it. It is inconceivable
that horticulture and agriculture should prove
exceptions to the general rule.
In the preparation of this book I have to acknow-
ledge much assistance. To Professor Bottomley
and his writings I am indebted exclusively for my
knowledge of his work and for the major part of
what I know about the subject in general. During
the years that I have known him he has at all times
given me access to his laboratory and to the reports
that have been sent in to him. Throughout he has
inspired, read, and criticized the manuscript of the
book. I also owe much to Mr. Alfred Machen, who
has shown and explained to me many of the experi-
ments now in progress on the land. The chapters
on the General Results from the use of humogen, on
the Application of Humogen, and the practical hints
in conclusion, are due entirely to him. Miss Mocke-
ridge, by her valuable criticism, has saved me from
x PREFACE
many errors, and helped me most materially in the
general chapter on chemistry.
I have to thank the Editors of several papers for
leave to make use of material published, notably
the Editors of the Proceedings of the Royal Society,
and the Edinburgh Medical Journal y the Annals
of Botany, the Journal of the Royal Society of Arts,
the Biochemical Journal, and Country Life. The
Editor of the Morning Post has kindly allowed me
to use the papers on the " National Food Supply,"
contributed by Mr. Charles W. Fielding. I have to
thank that gentleman and Dr. N. L. Watson-Wemyss
for the ready permission they gave me to make use
of their writings. I have consulted several books
in the course of my work, particularly The Geological
Survey of Ohio, by Dr. Alfred Dachnowski; The
Soil, by Dr. A. D. Hall; Bacteria in Relation to
Country Life, by Dr. Jacob G. Lipman ; and Soil Con-
ditions and Plant Growth, by Dr. Edward J. Russell.
I have also to thank the Editors of those papers
which I have quoted in the text for permission to
make use of the extracts that have appeared in
their columns.
In typing the manuscript of the book Mrs.
Marshall and her staff have very materially assisted
me by their promptness and accuracy.
GORDON D. KNOX.
u, GARRICK STREET, W.,
August 9, 1915.
CONTENTS
CHAPTER PAGE
I. THE NITRATE PROBLEM I
ii. ENGLAND'S FOOD-SUPPLY IN PEACE AND WAR - n
III. BACTERIA AND PROTOZOA - - IQ
IV. PEAT AND ITS USES - - - "31
V. FIXATION OF NITROGEN BY LEGUMINOUS PLANTS 46
VI. HUMUS ... 64
VII. BACTERIZED PEAT I ITS PREPARATION AND
GENERAL PROPERTIES - - 8 1
VIII. VITAMINES, ACCESSORY FOOD BODIES, AND AUXI-
MONES - - - - 96
IX. ELEMENTARY CONCEPTIONS OF CHEMISTRY IN
RELATION TO THE SOIL - - - IIQ
X. THE TESTING OF HUMOGEN - - - 135
XI. THE PREPARATION OF HUMOGEN - - 150
XII. PRESS AND OTHER CRITICISM ... 155
XIII. HOW HUMOGEN IS APPLIED - - 169
XIV. GENERAL RESULTS - 1 78
XV. HINTS AND EXPERIMENTS ... 197
APPENDICES ..... 205
LIST OF PAPERS - .... 239
INDEX ...... 241
LIST OF ILLUSTRATIONS
FIG.
1. GREVILLEA FROM KEW GARDENS - - Frontispiece
2. EFFECT OF HUMOGEN ON LILIES - - FACING PAGE g
3. BACILLUS RADICICOLA - - - 53
4. AZOTOBACTER CHROOCOCCUM - - 53
5. PRIMULA TREATED WITH AUXIMONES - -58
6. HUMOGEN CONTRASTED WITH LOAM AND COMPOST 60
7. HYACINTHS TREATED AND UNTREATED - "91
8. AN INSTANCE OF INCREASED VARIEGATION - 143
9. A TOMATO PLANT - - - - -145
10. POTATOES GROWN IN MOSS - - - 146
11. ROOT DEVELOPMENT - - - - 159
12. INFLUENCE OF HUMOGEN ON BARLEY - - 165
13. CARNATIONS IN INFECTED SOIL - - 1 66
14. TWO BEAN PLANTS - - - - 183
15. MAIZE PLANTS, SHOWING EFFECT OF AUXIMONES - 191
1 6. A CONTRAST IN RADISHES ... Tg^
17. PRIMULA KEWENSIS - - - - 212
THE SPIRIT OF THE SOIL
CHAPTER I
THE NITRATE PROBLEM
Geometric progression illustrated by bacterial growth — Geo-
metric character of advancing civilization — Latter-day
developments — Present prosperity — Threatened famine in
power and nitrates — Science to the rescue — Sources of
plant food — Cavendish and Bunsen — Electrically produced
nitrates — A nitrate balance - sheet — The outlook — In-
creased demand — Diminished supply threatened — Bacteria
as nitrate builders — Their use in agriculture.
PICTURE an observer suspended above the equator
of the earth, unaffected by the swirl due to the
earth's turning on her axis, but following closely
her movements through space. Assume that at an
instant in time he drops a bacterium on the hurry-
ing surface beneath his feet, and that the bacterium,
like the seed of the sower that fell on fruitful ground,
falls into a medium ideal for its growth and finds
nothing to check its power of reproduction. In
twenty-four hours, when the same spot of the
earth's surface was again beneath his feet, he would
find, instead of the single bacterium he had dropped,
a bacterial empire one hundred and seventy thousand
times as numerous as the present human population
i
2 THE SPIRIT OF THE SOIL
of ;<.he \vcrVl.;3t If tho bacterium were the anthrax
bacillus, and the members were well developed, the
length of each might be the five-thousandth part of
an inch, and, had they developed end to end in a
long chain during the short twenty-four hours spent
by the earth in turning on her axis, the progeny of
the original anthrax bacillus would have engirdled
the equator thirty-seven times, welded into a chain
close on a million miles in length. The vaunted
achievement of Ariel engirdling the earth fades to
nothingness beside the astounding energy shown
by the bacteria in their passionate longing to per-
petuate their kind. The facts of bacterial growth
stagger the imagination, but, like most things
measurable, they have been brought into some sort
of order, and expressed and fixed in rows of figures
by the mathematician. Marvellous as is the state-
ment made above, even the enlightened schoolboy
of to-day would see little to wonder at in it. Was
he not as a child fresh from home tricked into
attempting to estimate the value of the nails in a
horse's shoe when the first nail was priced at a
farthing, the second at a halfpenny, the third at a
penny, and so to the last nail, and did he not give up
the problem in despair ? Since then he has laboured
through the mysteries of the geometric progression
and realized something of the magic of numbers.
What, however, if it should turn out that in our
civilization to-day we have something comparable
* " With division occurring every half-hour, a single individual
could become in one day the ancestor of 280,000,000,000,000 bac-
teria " (Dr. Jaoob B. Lipman, Bacteria in Relation to Country
Life}.
THE NITRATE PROBLEM 3
with a geometric progression ? There are some who
would have us believe that the history of the earth
is a succession of cycles, that civilization attains to a
certain point, and then, like Sisyphus's stone, falls
back to the bottom of the hill, only to be rolled up
it again by toilsome effort. With such a conception
I have no concern here. Inevitably, recorded his-
tory tells us nothing of it. In any case we can know
of nothing except a small portion of the hill up which
we have been ascending, but the study of that small
portion of the hill is amply sufficient to stimulate our
imagination, and may be to arouse our alarm.
Quite early in the history of the world we can
glimpse at the material origins of civilization. Even
to-day there are great areas where the road exists
only in the primitive form of the track, where the
wheel is unknown; tradition, wrongh perhaps, has
brought down to us the tale of when and how the
wedge and the screw were first devised as aids to
man's enterprise. As we glance back over the pages
of history a matter of some three thousand years
we seem to see something in it which suggests that
the world's progress is a geometric progression, and
that we are at a point to-day when each doubling of
the terms in the series involves the most formidable
consequences. Can we realize that in the thirteenth
century lumps of coal were being given to the poor
in Scotland as alms, and that as recently as 1735 the
coal consumption of England attained only two
million tons in the year ? Do we appreciate the
fact that it is not until 1925 that we shall celebrate
the centenary of the first steam railway, that it
4 THE SPIRIT OF THE SOIL
was not until 1878 that the electric dynamo became
a practical machine ? In ancient Greece the
mariner who voyaged as far as the Pillars of Hercules
in Spain was a traveller expected to bring back
stories of monsters and other wonders, but to-day
there is not a portion of the earth's surface which is
not more or less exactly mapped.
Despite the poverty of the world, we are for the
moment living in a period of abundance, as witness
the violence of the attacks made upon Malthus,
who wrote at a period when it seemed that man had
reached the limits of his food-supplies. Between
then and now intensive agriculture has arisen as a
new art ; the great granaries of the world have been
available for all, thanks to the development of the
vast transport agencies. The mighty deposits of
nitrates in Chili and Peru, Stassfurt, and elsewhere,
have been mined to provide the farmer with the
necessary fertilizers, and at the moment the supply
is ample for the world's needs.
Those who care to look forward to the world's
future, however, are uttering, Cassandra-like, doleful
prophecies. The inroads made on the great forests
of the United States, especially, have been so serious
that the world is called upon to face the danger of a
timber famine. Commissions have been appointed
to estimate how long we may expect the coal reserves
which are being worked at a rapidly progressive
speed to continue to furnish their abundant energy
to the world. It is recognized that the time will
come, and is not so very far distant, when Canada,
the United States, and the other great wheat-pro-
THE NITRATE PROBLEM 5
ducing countries of the world, will be unable to furnish
more food than they require for their own con-
sumption. It was Sir William Crookes, now Presi-
dent of the Royal Society, who as President of the
British Association first startled the world by warn-
ing it of the menace to its food-supply. The in-
creased control gained by man over Nature — a
geometrically increased control — has enabled him
to draw on the capital stored in the ground to an
extent unthought of by his ancestors, and, like the
proverbial nouveau riche, he has been squandering
the treasure to which he has gained access. Appetite
has come with eating. The treasures that at first
seemed inexhaustible are now harder to win than
they were, are now showing signs of becoming
exhausted, and Nature is threatening to return our
spendthrift cheques to us marked with the red ink
comment, " No effects."
Experimental science, when this day arrives,
promises to treat us rather as an indulgent guardian
than as a hard-hearted money-lender. There is
happily in the sun a portion of an estate that we
have been able neither to sell nor to mortgage, and
when Sir William Crookes startled us into taking
stock of our resources, the men of science set to work
to see whether it might not be possible to make a
better use of our yearly income than under the
influence of an apparently unlimited capital we had
been doing in the past. Two foodstuffs in bulk are
necessary for the life of plants, Carbon and Nitrogen.
The first is omnipresent in the air, and under the
influence of sunlight the plants from the earliest
6 THE SPIRIT OF THE SOIL
times have seized it in the form of Carbon dioxide,
and changed it in their leaves to the form in which
they could assimilate it. The second, Nitrogen, is
also present in the air, but in such a form that no
plant is able to assimilate it or to combine it so as
to render it available for its use. Sir William
Crookes put the problem clearly and succinctly.
Either the world in thirty or forty years from the
date of his address was doomed to suffer from a
wheat famine unexampled in the history of the
world, or it was incumbent on the man of science
to find a practical means of inducing the inert nitro-
gen of the air to enter into combination with oxygen,
and form the nitrates essential for plant food.
There was one outstanding classical experiment
to guide the chemists in their elucidation of the
problem. In 1785 Cavendish discovered that when
an electric current was passed through air an acid
was formed, and seventy-two years later Bunsen
established that the acid so formed was Nitric Acid,
the Oxygen and Nitrogen of the air having been
induced by means of the energy of the electric dis-
charge to enter into combination to form the acid-
On this groundwork the chemists set to work, and in
a few years' time they had devised a practical method
whereby the water-power of the great waterfalls
could be used to produce a high-tension electric
current. The current was allowed to discharge
across a gap, was spread out by means of a powerful
magnet into a great disc of blazing, roaring flame,
which, on air being forced through it, induced the
Nitrogen and Oxygen present to enter into combina-
THE NITRATE PROBLEM 7
tion. By this and by other methods the chemists
have achieved a partial solution for Sir William
Crookes's problem. For they have found a method,
dependent on income and not on capital, whereby
the nitrates required for agriculture can be produced
at a cost that enables them to compete successfully
with the nitrates prepared from natural deposits.
The achievement is one of which the chemists may
well be proud, but after all it is only a partial solution.
We were threatened by Sir William Crookes with a
nitrogen famine, but since then men of science have
threatened us with an even more serious danger, an
energy famine. At present in coal we have an
abundant supply of energy available at a low cost,
but when this begins to give out the value of water-
power must advance by leaps and bounds, and force
up with it the cost of the manufactured nitrates to
such a point that the farmer will be unable effectively
to compete with the other potential users of power.
We are brought back therefore to a reconsideration
of the problem, and it may prove of value briefly and
roughly to formulate it in tabular form as follows :
Demand for
Nitrates. Sources of Supply.
Agriculture . . Nitrate deposits (already showing signs of
exhaustion) .
Explosives . . Chemical means (in all of these the utilization
of power on a large scale is essential) .
Various . . Farmyard manure, sewage, etc. (a decreasing
source, which in some cases will not pay
the cost of collection).
Bacteria (as in those associated with leguminous
plants, and as those cultivated by the new
system of treating peat). These are only
indirectly a source of nitrates, as they form
complex nitrogenous food substances rather
than actual nitrates.
8 THE SPIRIT OF THE SOIL
There seems no reason to believe that there can
ever be a lessened demand for nitrates. With the
continued increase both of population and of
standard of comfort, and with the rapid exhaustion
of the virgin soils that were to be met with in the
early days of farming in America and Canada, the
drain made on the world's stock of nitrates by agri-
culture must continue to increase; the present war
indicates that the demand made by explosives for
munitions of war will be more than maintained, while
great engineering works will probably absorb more
than in the past. Lastly, with the increased activity
of the chemical trade it seems inevitable that in this
direction, too, a further increase in the production of
the world's nitrates will be essential.
From the standpoint of supply the situation at
first sight does not seem promising. As Sir William
Crookes pointed out, the exhaustion of the natural
deposits is already in sight, and there seems no valid
reason for believing that new sources of nitrates will
be discovered to replace the old. Chemical pro-
ducers of nitrates will before long find themselves in
serious competition with other users of power. With
the introduction of the motor car farmyard manure
will become less and less available, while at present it
has seldom proved practicable to utilize the waste
sewage produced in the great towns. As one writer
has expressed it, it is no more reasonable to quarrel
with the farmer for not utilizing the sewage of the
towns than it is to quarrel with the manufacturers
for not collecting and burning the vast masses
of carbon that are poured out daily from the
FIG. 2
The left of the two lilies shown above was grown in humogen and
ordinary soil, while that on the right was grown in a complete food
compost. The average number of blooms on the batch (48 size
pots) was six as against four, and it should be noted that this
is the common effect of humogen treatment on bulbs.
(The Royal Gardens, Kew.)
THE NITRATE PROBLEM 9
private chimney-pots of householders in the great
cities.
There remains one great source of nitrates and a
great army of workers adapted from the beginning
of time for the fundamental work of nitrate pro-
duction, fitted for that work and that work alone,
an army of workers that require only the intelligent
co-operation of the farmer and the man of science
efficiently to perform their duties — the bacteria of
the soil. It is the purpose of this book to show how
an English man of science working in an English
laboratory has set out to solve the problem of
facilitating the work of the soil bacteria, how the
experiments carried out in laboratory, hothouse
and field, all go to prove that the bacteria of the
soil intelligently applied cause a growth of crops
heavier than that obtained by manures owing to
the steady supply of nitrogen that they furnish to
the plants, and owing to the potash and phosphate
that they render available, and, lastly, how in the
course of his researches he has been forced to believe
in the existence and potency of certain mysterious
accessory food substances produced through the
action of the bacteria, which bring about a develop-
ment of plant life unparalleled by any manure
hitherto known, whether natural or artificial.
I have no wish that these statements should be
accepted on the ipse dixit of the workers themselves,
or of those who have conducted field experiments.
In the following pages the attempt will be made to
describe simply the laboratory results of the last
eight years' work at the Botanical Laboratories of
io THE SPIRIT OF THE SOIL
the University of London King's College. At the
same time an account will be given of the results
obtained in the field. I shall describe, too, what I
have seen myself in some stations at which large
scale experiments are now in progress, and in con-
clusion I shall give in their own words the opinion of
practical agriculturists on the material used and the
results that they have obtained. On these bases,
and, if need be, on experiments conducted by himself,
each man will decide for himself whether or not the
saving of the present situation and the future of
agriculture rests with the bacteria of the soil. For
my own part I have no uneasiness as to the verdict.
CHAPTER II
ENGLAND'S FOOD-SUPPLY IN PEACE AND WAR
Laisser-aller policy — Two months' famine margin — Wheat-
growing in England and abroad — Wheat imports — Decay
of wheat-growing in England — Increased acreage yield
abroad — Stagnation in stock-raising — Inevitable wheat
shortage — Redistribution of crops suggested — Difficulties of
the scheme — The competition for nitrates.
BITTER experience gained in the present war is
forcing home the lesson that too heavy a price may
be paid for the pursuing of an easy-going policy of
go-as-you-please. Were the price demanded only
that of British treasure, the non-organization of the
country would be stupid and suicidal. But the cost
of it to-day, as we have had to read the reckoning,
is the lives of our fellow-men sacrificed to our past
blindness and the unspeakably grave peril, not yet
for a certainty surmounted, that Britain may be
humbled to the dust through famine.
The voices of those preaching agricultural reform
are the voices of men crying in the wilderness, calling
attention to a risk as grave as that which Lord
Roberts was never tired of voicing ; but the country
closes its ears to those who tell it of the risk just
as they callously ignored the need of anything
approaching national service.
ii
12 THE SPIRIT OF THE SOIL
It is, however, notorious that Great Britain lives
from day to day with a margin of but two months
between her and famine. Let the seas be closed
only for that period to merchant vessels, or let the
nations that send her their corn from the harbours of
the Seven Seas be unable to launch their supplies,
and the price of wheat will mount by leaps and
bounds until the poorer classes of the country will
find it impossible to buy a loaf of bread. This is the
tragic side of the picture, but on other grounds than
those of the immediate national danger the situation
calls for reform. It is not the truth that English
land is unsuited for wheat-growing, or that the great
percentage of the land is inferior to that cultivated
in France or Germany. The problem exists in an
equally acute form as regards stock-raising, and
in that connection is no less urgent in demanding
a solution. And from both standpoints the issue is
bound up with soil fertility.
Few who are not expert agriculturists can have
any conception of the vast discrepancy between the
conditions prevailing in England and those obtaining
abroad. The situation, however, has been carefully
studied and explained by several observers, notably
in the early months of this year by Mr. C. W. Fielding
in the columns of the Morning Post, and it is from
his articles based on official figures that the chief
conclusions of the present chapter are drawn.
In agricultural produce England buys from abroad
the enormous total of £333,000,000 worth of im-
ported soil products, a value £133,000,000 greater
than the total manufacturing exports, once deduction
ENGLAND'S FOOD-SUPPLY
is made of the cost of the raw material imported in
connection with their manufacture. The first ques-
tion naturally arising out of this statement is how far
this volume of imports is a necessary condition of
England being a manufacturing country, and a pro-
visional answer is given most simply by a comparison
between the conditions in the United Kingdom,
France and Germany.
United
Kingdom.
Germany.
France.
Total acreage under cul-
tivation
48,000,000
86,000,000
67,000,000
Of which acreage under
plough
Of which acreage under
20,000,000
65,000,000
47,000,000
grass
28,000,000
21,000,000
20,000,000
Percentage of cultivated
surface in grass
60 per cent.
60 per cent.
30 per cent.
Acres growing bread
grain
1,791,000
20,000,000
19,500,000
Percentage of total culti-
vated area growing
bread grain, about . .
3 per cent.
25 per cent.
30 per cent.
Total quarters bread
grain produced
7,000,000
73,000,000
47,000,000
Production of bread
grain per head of
population
90 pounds
485 pounds
500 pounds
Head of cattle
11,000,000
20,000,000
14,000,000
Population
45,000,000
65,000,000
40,000,000
Population engaged in
agriculture
1*350,000
10,000,000
8,000,000
Percentage of popula-
tion engaged in agri-
culture
3 per cent.
1 7 per cent.
20 per cent.
Bushels bread grain
produced per acre of
total arable land
3
9
8
Acres grass used per
head cattle, about . .
3
i
ii
THE SPIRIT OF THE SOIL
These statistics are startling to anyone who has
the interests of the nation at heart, and the dis-
crepancy between the practice of Great Britain and
that of her great Continental neighbours stimulates
a further inquiry. There is a grave challenge to
British farming in the statement that only 3 per cent,
of our cultivated land is employed in growing wheat
as opposed to 25 per cent, in Germany and 30 per
cent, in France.
The conditions have not always been the same as
they are to-day, and the gravity of the problem is
emphasized more clearly by a further comparison
made with other countries. During the last thirty
years in the countries mentioned below the total
acreage under cultivation has varied little, but the
attention paid to the growing of wheat has enor-
mously increased everywhere except in England*
where there has been a large fall in output, as is
shown from the following table :
Germany has increased her wheat production
France
Russia
Hungary
Roumania
Bulgaria
25 per cent.
7
90
25
33
22
While the output of the United Kingdom has fallen 30
An attractive explanation of the situation would
be that the pressure of population in other countries
had forced into wheat cultivation land unsuited for
it, and that the increased acreage and increased
gross yield on the Continent was only obtained by
sacrifices of such an order that the farmers of this
country did not care to follow suit. An analysis of
ENGLAND'S FOOD-SUPPLY
the figures, however, shows a further disquieting
result. During the period considered the yield of
wheat per acre in the United Kingdom has remained
absolutely stationary, while in those countries that
have increased their acreage under wheat the yield
has risen from between 15 to 40 per cent. The
following is the detailed comparison :
In Germany the yield has gone up
In France
In Russia
In Hungary
In Roumania
In Bulgaria
40 per cent.
18
20
15
20
25
Perhaps it may be thought Great Britain makes
up for her deficiencies as a wheat-grower by a marked
predominance in stock-raising. The facts unfortu-
nately are otherwise, as the figures again show :
In forty years the German stock of
cattle has increased from . .
And pigs from
France: Increase of cattle from
Increase of pigs from
Belgium : Increase of cattle from
Increase of pigs from
Hungary : Increase of cattle from
Increase of pigs from
The United Kingdom has increased cattle only from 10,000,000
to 11,000,000; while the stock of pigs remains practically the
same — viz., under 4,000,000.
15,000,000 to 20,000,000
7,000,000 to 22,000,000
11,000,000 to 14,000,000
5,000,000 to 7,000,000
1,200,000 to 1,800,000
600,000 to 1,300,000
5,000,000 to 7,000,000
4,000,000 to 7,500,000
In normal times the situation is a grave one for the
nation, but in view of the European War it offers a
menace of exceptional gravity. Let us assume, as we
have now perhaps a right to assume, that the allied
navies will preserve the freedom of the seas as mag-
nificently inviolate to the end of the war as they have
done during the first twelve months of it, and that we
16 THE SPIRIT OF THE SOIL
have therefore no reason to fear any artificial stop-
page of our overseas supplies. The Navy, despite
its success, cannot influence the shortage in corn-
stuffs that has been brought about inevitably owing
to the war.
As Mr. Fielding points out, it is the richest wheat
area of France that has suffered German invasion;
East Prussia and Galicia, both of which have suffered
invasion, are the most important grain-growing areas
in Germany and Austria. Belgium in normal times
is a wheat importer, but with her territory violated
will have grown less than usual, and will have to
make a larger demand than usual on the general
supply. Russia, in normal times a large exporter,
can now not only have little if any to export, but
with the Dardanelles at present closed may be unable
to send any supplies to the European market. The
shortage of the European harvest is estimated by
Mr. Fielding to be very large, and the only source
from which an increased supply over the normal
can reasonably be expected is from Canada ; and the
bulk of any Canadian increase of wheat must be at
the expense of reduction of other crops in Canada.
The situation therefore is that, with the shortage
of European output caused by the war, other
countries of the world will have to supply enor-
mously increased quantities.
To meet the present deficiency and to make Great
Britain self-supporting there is no need to have
recourse to such sensational means as the bringing
of Scottish deer forests under cultivation. All that
would be required would be to reallot the uses. to
ENGLAND'S FOOD-SUPPLY 17
which the ground under cultivation is put at present,
to devote 8,000,000 acres to wheat, 16,000,000 acres
to general plough cultivation, and 24,000,000 acres
to grass. By these means England would be self-
supporting as regards her wheat-supply.
It is not suggested that the situation is an easy
one to settle. Many complex interdependent factors
enter into it, fiscal, economic, social and practical,
and in times of peace a great deal of business and a
great deal of thought would be necessary before the
problem could be effectively approached. To-day,
however, the country is at war, and the food problem
is only second in urgency to that of maintaining our
armies at the front and of supplying them with
munitions. A single condition stands out with un-
mistakable clearness. The internal wheat-supply of
Great Britain must immediately be very considerably
increased. Abroad in times of peace our neighbours
have solved the problem of feeding their own popu-
lation by intensive cultivation, but whereas both
France and Germany use 105 pounds of artificial
fertilizers to the acre, England makes use only of
48 pounds to the acre. The need has now arisen
with exceptional urgency to get the utmost food
value possible out of the soil — wheat for the direct
consumption of man, pasture and other foodstuffs
for the purposes of stock. And this exceptional need
has arisen at the very moment when the demand
on the world's stock of nitrates has attained a maxi-
mum hitherto undreamt of. It finds the British
soils at a dangerously low ebb in their available
supplies both of phosphates and of nitrates, and if
i8 THE SPIRIT OF THE SOIL
large tracts of our land are to be laid down in wheat,
these must be supplied to them at no matter what
the cost. To-day the country is called upon to face
at once under the exceptional conditions of war the
very problem that will have to be faced in years to
comef as a result of natural developments. The
response made by men of science, above all by the
bacteriologists, to the note of warning in 1898 by
Sir William Crookes suggests that we may be in a
position to-day to meet the demand without un-
due expenditure.
CHAPTER III
BACTERIA AND PROTOZOA
The annus mirabilis — Developments of the modern era — The
atom — Electricity — Medicine — Greek decadence due to
malaria — Extension of human knowledge — Mendel — The
new romance — The role of the earthworm — Bacterial
empires in the soil — Their vicissitudes — Their work —
Bacteriology and astronomy — Properties of the bacterium —
Advances in pathology — The situation in botany — Broad
generalizations — Work and habits of the bacteria — Prepara-
tion of farmyard manure — Carbohydrates and proteins —
Break-up of carbon compounds — Three groups to deal with
proteins — Value of farmyard manure — Denitrifying bac-
teria and nitrogen fixers — The protozoa.
AN epitaph dating back to the most glorious period
in Athenian history has set down in terms of noble
simplicity the record of the great Athenians who
perished fighting for the country on salients of
offence that had been thrown out in all directions
into Greece and into all the barbarian hinterland.
The world, latinized, has since spoken of the period
as the annus mirabilis, and the epitaph sums up
grandly the stupendous blaze of energy that kindled
the intelligence of the world, and still acts to-day as
its most potent quickening force. It is open to
question, however, whether the Greeks ever realized
the astounding phenomenon in which they played
their part, just as it is open to question to-day
20 THE SPIRIT OF THE SOIL
whether we realize the unparalleled developments of
the present era.
Contrast for a moment the position of affairs as it
was in 1850 and as it is to-day, looking only along a
very narrow front. We had learnt by long and
painful experiment that all matter was composed of
elements, and Mendeleeff had drawn up his famous
table showing that there was some kinship between
the atoms. To-day we have made the tiny atom
almost visible, been able to watch the spark that
its impact makes, traced out its path as it hurls itself
through a gas, shattering the molecules that would
bar its way, learnt something of the subtler matter
of which it is composed. In electricity only the
broad foundations of the science had been laid; the
telephone was not conceived of even by the dreamer ;
the telegraph was already doing pioneer service in
shortening the world's distances; but no man had
conceived of harnessing the ether and forcing it to
carry the impulses impressed on it by the electric
spark. Medicine was still in an earlier era. Chloro-
form as an anaesthetic had barely been discovered,
and the surgeon, ignorant of the nature of infection,
could not dare to take advantage of more than a
tithe of what it offered. Then came the work of
Pasteur and of Lister, bringing in its train a flood of
knowledge that has swept away the dull mass of
ignorance, spread since the beginning of time across
the path of man's progress. Had the knowledge of
to-day been available to the Greeks, there would have
been no need for the sudden eclipse of her civilization.
It was not her internal dissensions that destroyed
BACTERIA AND PROTOZOA 21
her, but the sudden inroad of malaria that carried
off the best of her sons, left the race de-energized,
and forced her to hand on the torch of civilization
to the victorious Romans.
Just as the genius of Greece quickened into
activity the earlier of the arts and sciences, so the
genius of modern Europe is to-day extending in all
directions the horizons of human knowledge. Are
not the biologists following out the great principle
glimpsed at by Mendel, analyzing the factors of
heredity, and groping after the elucidation of one
of the supreme mysteries of the world ? Is it not
true that the experimental botanist is using a sure
method to recombine the qualities of the plants and
evolve new species, as a watchmaker might take the
parts he needed from a dozen watches and build up
a new one to suit his purpose ? Have we not found
that the earth is something more wonderful than
any thought her before ? The Greeks looked on the
goddess Gsea as the mother of mankind. In their
glorious mythology they pictured that men and
women had broken into life as the stones cast on to
her touched her life-giving soil. Countless legends,
expressed in astonishingly beautiful imagery, have
told of the sacrament of spring, and the Celt has
peopled the soil with gnomes and pixies, friends or
enemies to man. Science working with polished
microscopes, with bottled reagents, with curiously
twisted retorts, and all the paraphernalia of the
laboratory, has rent in twain the closely knit and
woven veil that barred our access to the mysteries
of earth, and as these are revealing themselves to us
22 THE SPIRIT OF THE SOIL
the wonder of them far transcends all that the
imagination of the poet has conceived. In setting
aside the romance of the past the laboratory is
guiding us to an astonishingly greater romance of the
present. The child's " Let us pretend," a pitiful
attempt to furnish the food that its imagination
demands, gives place to the cry of " Let us know,'1
and in imaginative splendour the knowledge of
to-day presses out beyond all that was previously
conceived.
Who in the past could have imagined the mys-
terious happenings that take place in a small plot of
garden soil ? It was a revelation to the world when
Darwin, lifting a corner of the veil, told of the stu-
pendously great part played by the earthworm that
had been " carrying on " unheeded or resented for
countless ages of time. But to-day we are beginning
to know that the soil which the gardener turns with
the spade is the site of countless vast empires of
bacteria. They are empires that rise and fall in the
short space of weeks, that have great tasks to per-
form, and devote themselves wholeheartedly to
carrying them out, empires liable to countless vicissi-
tudes. Now they are overwhelmed by the vast
immigrations that come to them suddenly as gar-
dener or husbandman pours into their borders
countless myriads of individuals with each spadeful
of his manure. Periods of drought wreak havoc on
their colonies, the lives of whole empires being
dependent on the chances of the climate. They are
preyed on by monstrous protozoa that may exact
a greater toll than even they with their astounding
BACTERIA AND PROTOZOA 23
fertility can cope with. Or they may perish through
their own activity, their life clogged by the products
they have themselves formed. Widely they differ
among themselves. Some of them build up, others
of them destroy ; even in the same species there are
vast differences. Like communities of men and like
single individuals, there are some that are energetic,
others that are lazy, others that are tired; as food
fails, or is abundant, they are poorly fed or well
nourished. They are healthy or sick. To a bad
environment or a good one they respond as readily
and as notably as the people in our great cities, and
with them, too, their heredity has a dominating
influence.
Only within recent years have we realized how in-
timately our prosperity is dependent on the bacterial
population of the soil. Without bacterial activity
it would be of no avail to the farmer to dung his
crops; it would be useless for him to attempt to
enrich his soil by ploughing in green stuff. The
plants and trees that have lived and died wresting
Carbon from the air would only cumber the land.
All vegetation would be choked, and the earth would
become a vast wilderness, unbeautiful and silent,
save for the winds and seas and other manifestations
of lifeless forces.
Though at present we are only groping as pioneer
discoverers in a new universe, there are some great
features that we are able plainly to recognize, dimly,
it may be, as astronomers who map the surface of
the moon. As the astronomers can speak with
certainty of the mountains of the moon, of the con-
24 THE SPIRIT OF THE SOIL
ditions of its atmosphere, of the laws governing its
movement through space, so there are many proper-
ties of the bacterium on which it is safe to dogmatize.
We know that the bacterium is an organism low in
the vital scale, consisting of a single cell, the proto-
plasm or vital unorganized portion of which is sur-
rounded by a cell membrane which may consist of
cellulose, but which more often is made up of a horn-
like substance. We are on sure ground when we
state that it usually reproduces its kind by forming
a partition in the middle of its substance and dividing
into two. Observation has taught us that the time
taken for division is in favourable conditions about
half an hour. It is certain that in the vast kingdom
of the bacteria there are only a few that are able to
give rise to diseases in man and animals. Most of
these have certain characteristics that enable them
to be certainly identified and incriminated by the
bacteriologist. The pathologist has gone farther,
and is getting an insight into the means by which
the body is able to repel the attacks by which it
is constantly threatened. He talks learnedly of
opsonins, antibodies, and the like, and his know-
ledge at any rate is sufficiently precise and accurate
to enable him to build up on it a rational system
of treatment for the individual struck down by a
disease.
While the bacteriologist who has directed his
attention to the bacteria connected with the causa-
tion of disease stands on a firm foundation of proved
and demonstrated fact, and may compare his results
with those with which the astronomer deals in
BACTERIA AND PROTOZOA 25
mapping the moon, and in computing her orbit, the
position of the bacteriologist who is grappling with
botanical and agricultural problems is far less
enviable. He must be compared rather with the
men who are making a study of Mars. There are
certain broad facts of which he can speak with
certainty, but as regards others he is beset with
controversy, struggling as it were to put a correct
interpretation on the vague markings that he speaks
of provisionally as the canal system of Mars. There
is no dispute now as to the prominent part that
bacteria play in relation to soil fertility. It is a
commonplace that in an ounce of rich loam soil there
may be as many as 150,000,000 bacteria, while in
ground polluted with sewage the number may reach
the fantastic total of 3,000,000,000. Much, too, of
the work that the bacteria accomplish and of their
habits is known, proved and accepted. Warmth
and a moderate amount of moisture promote their
growth; cold and excessive moisture or excessive
drought arrest their development. There are some
that can thrive in the presence of air, others that can
only do their work if air is rigidly excluded. The
function of some of them is to break down complex
substances to simpler bodies or even to elements;
the function of others is to build up substances of
high potential energy from inert constituents. With-
out their activity the world would rapidly arrive at
a deadlock. The material of plants and animals that
had reached and passed their prime would cumber
the ground, and the fabric of their tissues would
not, as now, become available as the raw substances
26 THE SPIRIT OF THE SOIL
from which other plants and animals can build up
their tissues.
Such are some of the broad generalizations that
constitute the foundations on which the plant
bacteriologist is called upon to build, and already
from them he has been able to formulate other
narrower generalizations that are of vital importance
to the art of agriculture. We shall see more of them
in later chapters, but it may be helpful at this stage
barely to outline the chief points on which, as we
know it at present, the question of soil fertility from
the bacterial standpoint mainly depends. One may
accept it as broadly true that we know the con-
ditions of soil fertility if we are able to trace the
processes by which a load of farmyard manure
becomes available as plant food.
When the manure is thrown freshly on to the heap
it consists essentially of a heterogeneous mass of
material, loaded up with bacteria, and containing a
great variety of Carbon compounds, with traces of
Phosphates, Potash, and so forth. It is with the
Carbon compounds that we are concerned. These
fall into two great classes — that in which the Carbon
is combined with various quantities of Hydrogen
and Oxygen, and that in which Nitrogen is also one
of the constituents (the proteins). As they are
found in fresh manure neither class is available as a
plant food. Common farmyard experience tells us
that the manure-heap heats and shrinks, and it needs
no great effort of imagination to realize that a process
is at work comparable with what occurs when a bon-
fire is being burnt. And this is actually what is
BACTERIA AND PROTOZOA 27
taking place ; but whereas in the bonfire a tempera-
ture is reached at which the oxygen of the air is able
directly to combine with the Carbon compounds and
break them down into Carbon dioxide and Water, in
the manure-heap a similar but slower and less com-
plete process is occurring. This change is the
earliest to be noticed, and though other changes are
happening at the same time, they are more logically
considered as being later. In the first instance the
bacteria — there are varieties that can do the work
in the presence of air if the heap is loosely com-
pacted, and varieties that can accomplish it if all
air is excluded — break down the complex Carbon
compounds, turning them into simpler bodies, and
partly into Carbon dioxide that escapes into the air.
These nations of bacteria wax and wane, giving place
to three separate groups that one after another deal
with the nitrogen compounds. The bacteria called
upon to deal with these bodies have to be fed with
readily assimilable carbon compounds. The first
group, some of whose members can work with air
and others without, seize on the nitrogen fixed in
complex groupings and split off ammonia from the
protein (NH3). Their finished product they hand
on to another group. These can only work in the
presence of air, and they require lime or some basic
material to absorb the acid they produce. Under
their influence the ammonia they have had passed
to them as the raw material (often in the form of
Ammonium Sulphate [(NH4)2SO4]) is changed into
nitrite (NO2), and this by a third group, also acting
in the air, and in the presence of a base becomes
28 THE SPIRIT OF THE SOIL
nitrate (N03), which will be found in the heap in
some such soluble form as Calcium Nitrate
[Ofc(N08)J.
Apart from the value of its mechanical structure,
and apart from the Phosphates and Potash that it
contains, the essential value of farmyard manure to
the land is that it possesses sufficient carbon com-
pounds in assimilable form to act as a food-supply
for the bacteria, and that it contains a large supply
of the nitrogenous food material essential for plant
nourishment.
This is not the whole story, however. The bac-
teria of which I have so far spoken are the fairy god-
mothers of the romance — the fairy super-godmother
has not yet appeared on the stage — but the romance
itself would be incomplete if there were no hard-
featured, cross-grained witch. Experience has long
taught that the loosely piled heap will burn away
to waste if it is too loosely stored owing to the exces-
sive amount of oxygen supplied to the first group of
bacteria. In agriculture, as in politics, the advice of
Talleyrand especially as regards bacteria surtout pas
trop de zele is eminently sound, but however carefully
he goes to work, the farmer may find that the cross-
grained witch has come uninvited to the feast in the
shape of a denitrifying bacterium that seizes on the
precious nitrates designed as plant food, and waste-
fully turns them into the nitrogen that is useless for
plants, and escapes inert into the open air.
It is the super-godmother, however, that comes to
the rescue. A group of bacteria exists; the name
of one of the group is Azotobacter, and it has the
BACTERIA AND PROTOZOA 29
power of starting with the inert nitrogen of the soil
air and of changing it into nitrogenous plant food.
The rotted manure gives it the food of which -it
stands in need, and under favourable conditions it
is able to go on steadily adding to the store of nitrog-
enous food material in the soil.
Such in crudest outline is the function of the soil
bacteria and the way in which they lead to an
increase in soil fertility. In the chapters immedi-
ately following I shall endeavour to describe their
work in greater detail, and to show how it is possible
for man successfully to co-operate with them. A
word, however, in conclusion of this chapter must
be written of the protozoa, for though they are not
concerned with the general argument of this book,
they bear an important relation to the soil bacteria
and seriously affect their welfare.
The protozoon is not a bacterium, but a minute
animal requiring the magnification of a strong micro-
scope lens to be seen. Small though he is, he is as
terrible and monstrous a foe to the bacteria as the
vast swamp monsters must have proved to emerging
man in the Eocene times. Looked at in water under
the microscope he is seen creating in the medium
whirlpools against which the hapless bacteria are
powerless to contend, and drawing them defenceless
into his body. Recent experiments at Rothamsted
have shown that these animalculae in certain con-
ditions may seriously check the bacteria of the soil,
and may gravely affect the health of plants, especially
in rich, ^ highly-manured soil. Experimentally in
horticulture it has proved practicable to get rid of
30 THE SPIRIT OF THE SOIL
them by chloroform and other similar means, and it
seems as if the burning of cultivated soil by the
Indians, a practice dating back to traditional periods
of Indian agriculture, may have had as one of its
benefits the destruction of the protozoa of the soil.*
Fortunately they are less resistant than the bacteria,
and when these stringent methods are employed all
the protozoa perish, while a considerable number of
the bacteria are left, and these, rid of the protozoan
enemies, are able to jump into an amazingly rapid
development and continue their work of securing a
suitable soil environment for the plants. It is,
however, only in excessively manured soils that they
constitute a serious problem, and this short account
given of them may therefore suffice.
* Cf. Virgil, Georgics :
" Often you will find it well to burn
The garnered field and set the flimsy straw
A-cackling in the flames. Whether perchance
The land in this wise finds some unknown force,
Some fat enrichment ; or that every fault
Thereby is purified by fire, and all
The useless humours purged ; or that the heat
By its own virtue loosens secret pores
And paths unseen whereby the sap may flow
To the young grasses."
CHAPTER IV
PEAT AND ITS USES
Early investigations of the Royal Society — Continuity of mental
processes — Reality of material progress — Diamonds and
peat: an analogy — Conditions of peat deposition — Its con-
stitution— Variations in composition — Mineral and organic
residues — Peat formation — Peat, lignite, and coal — Extent
of peat deposits — Uses of peat — Fuel — Power — Chemical
products — Paper — Artificial wood mattresses — Surgical
dressings — Litter — Dr. Dachnowski's views — Objections to
peat as manure — Experiments with peat-moss litter at
Kew Gardens — Deleterious effects — Dr. Voelcker's explana-
tion— Contrast with humogen.
IF those who affect to consider that there has been
no advance in the world's knowledge during the last
quarter millennium would study the early history of
the Royal Society, founded a little more than 250
years ago, they would be amazed chiefly by two
points. The first would be the completeness with
which the founders and early Fellows of the Society
adopted the methods of observation and experiment,
reasoning according to completely modern methods
of thought, and the second the appalling extent of
ignorance that prevailed among those who were the
best instructed and most enlightened of their time.
Men steeped in literary lines of thought are fre-
quently pleased to quote with smug expressions of
31
32 THE SPIRIT OF THE SOIL
approval the old French saw, Plus ca change, plus
c'est la meme chose, and affect an almost personal
triumph when they are able to show that the passions
and mental processes in man to-day are strictly com-
parable with those prevailing in the earliest historic
times. They seem to believe that in emphasizing
the fact that the various races of men are fixed types,
variable only within the limits of a fixed type,
they are confuting the idea of there being any possi-
bility of progress. In doing so they belittle and
deny the value of the material advances made,
blinding themselves to the real facts of progress.
When one cares to go back to the original records,
however, the reality of this material progress is
strikingly brought out. In turning over at random
notices of the early investigations made by the
Fellows of the Royal Society, one comes across such
records as the following :
" March 25, 1661. — Mr. Boyle was desir'd to bring
in the name of the place in Brasil where that wood
is that attracts fishes ; and also of the fish that turns
to the wind when suspended by a thread/'
" May 8. — Dr. Clarke was intreated to lay before
the Society Mr. Pellin's relation of the production of
young vipers from the powder of the liver and lungs
of vipers."
" June 5. — Col. Tuke related the manner of the
rain like corn at Norwich, and Mr. Boyle and Mr.
Evelyn were intreated to sow some of those rained
seeds to try their product/'
" June 26. — Sir G. Talbot brought in his experi-
ments of sympathetick cures/'*
* The following extract from this paper may be of interest :
" An English mariner was wounded at Venice in four severall
PEAT AND ITS USES 33
" July 10. — The fresh hazell sticks were produced,
wherewith the divining experiment was tried and
found faulty.
" September 4. — Sir K. Digby brought in a letter
from a friend of his in Florence, written in 1656,
which treats of a petrified city and inhabitants."*
Instances of this sort could be quoted almost
indefinitely to show the extent of the prevailing
ignorance of natural phenomena, and a great debt
of gratitude is owed to the Royal Society even in
those early days for their fearless investigations. A
source that they used largely for extending their
knowledge was to make inquiries of sea captains and
of residents in foreign countries to confirm or refute
the astonishing stories that were brought from
abroad to this country. Sprat, in his History of the
Royal Society, prints a long list of the questions
addressed by the Society in its early days to Sir
Philiberto Vernatti, resident in Batavia, and of his
answers. The first of the questions is :
places soe mortally, that the murderer took sanctuary, the
wounded bled three days without intermission ; fell into frequent
convulsions and swounings; the chirurgeons despayring of his
recovery, forsook him. His comrade came to me, and desired
me to demand justice from the Duke upon the murderer (as sup-
posing him already dead) ; I sent for his bloud and dress'd it,
and bad his comrade haste back and swathe up his wounds with
cleane linen. He lay a mile distant from my house, yet before
he could gett to him, all his wounds were closed, and he began
visibly to be comforted. The second day the mariner came to
me, and told me his friend was perfectly well, but his spirits soe
exhausted he durst not adventure soe long a walke. The third
day the patient came himself to give me thanks, but appeared
like a ghost; noe bloud left in his body."
* Weld, History of the Royal Society.
3
34 THE SPIRIT OF THE SOIL
" Q. i. Whether Diamonds and other Precious
Stones grow again after three or four years, in the
same places where they have been digged out ?
"A. Never, or at least as the memory of man can
attain to."
When one turns from the ancient records of the
Royal Society to a book published so recently as
1912 on the Peat Deposits of Ohio, by Dr. Alfred
Dachnowski, it comes as a surprise to read the fol-
lowing remark almost at the opening of his first
chapter :
" Exact and systematic study of peat began in
Europe in 1750, when various scientific societies
offered prizes for memoirs on the origin, formation,
and nature of peat. Then, as to-day, some persons
held that peat bogs were useless obstacles to com-
merce and agriculture; were places of malarious
fevers and the causes of spring frosts; while others
advanced the idea that peat, if once dug out, would grow
again spontaneously ."
This quotation is, I think, memorable in showing
how greatly the oldest of the sciences, agriculture,
in certain of its aspects at any rate, lagged behind at
a time when the modern world had begun to show
an active, intelligent, scientific curiosity into the
causes of all sorts of natural phenomena.
The general conditions under which the deposits
of peat were laid down are to-day thoroughly well
understood from the general standpoint, though a
vast amount of work remains to be done before the
various problems connected with peat formation
can be regarded as solved. As with most natural
substances peat is the name given to a class of
PEAT AND ITS USES 35
products, and the term no more describes a definite
unit compound or mixture than does the term " coal"
in the mineral kingdom, or the terms "horse,"
" dog," " man," or what not in the animal kingdom.
As will be seen in the later pages of the book, it
would not be possible for the makers of bacterized
peat to copy the immortal recipe of Mrs. Beeton,
beginning, " Take a hare," and to start off an account
of their manufacturing process with the words,
" Take a ton of peat." The exact character of any
peat that is to be used has carefully to be studied
and tested to discover whether or not it will give
satisfactory results when converted into humogen.
Generally one may describe peat as disintegrating
vegetable matter. It may be coarsely fibrous and
matted, and contain plainly recognizable in its sub-
stance the roots, rhizomes, and aerial parts of plants.
Or it may be highly compact; the fibrous con-
stituents of it may have already decomposed and the
great portion of it may consist of disintegrating
leaves and woody parts of trees and shrubs. These
may be regarded roughly as the limiting substances
in one direction, and the other of the various agglo-
merations that may be described as peat ; but both
in chemical and mechanical properties there are
enormous differences. One has only to consider the
conditions in which the peat has been laid down to
realize that this is inevitable. Imagine the vastly
differing matter that is waterborne by various
streams to be deposited in the rankly growing vege-
tation of the forming peat bog. Bear in mind the
dust carried by the air, much of which has inevitably
36 THE SPIRIT OF THE SOIL
been trapped on the leaves of the growing plants.
Consider the differences in the animal organisms,
crustaceae, and so forth, that have lived and died
during the long periods of geological time, and there
will be little trouble in recognizing that in mineral
content one peat bog will differ widely from another.
This variation in life is a factor that has constantly
to be borne in mind when dealing with peat, and the
plants of which it is composed. Pond, lake, bog,
forest, and swamp, have well-defined differences in
the vegetation that grows on them, and the plants
growing in each will vary with changing conditions
of soil, climate, and general environment. The juicy
character of water-plants is perpetuated in the peat
they form by a soft structureless material. When
sedges and grasses predominate, the peat, as one
would expect, tends to be fibrous and of the nature of
turf. From trees and shrubs is derived a woody
type of peat.
To those not professionally concerned with the
problem it is often somewhat of a puzzle to say why
in certain cases coal is formed as the result of the
decay of vegetable matter, while in other cases peat
results. Peat must be regarded as the result of the
first of the great changes undergone by organic matter
on its way to become coal. What has occurred is
that plant debris has accumulated in a relatively
permanent body of water or in moist shallow places.
Weathering processes set in as soon as the tissues are
lifeless, promoted and aided throughout by the action
of fungi and bacteria. The products of decay accu-
mulate beneath the surface of the water, and in the
PEAT AND ITS USES 37
absence of air the bacterial activity is checked, and
complete resolution of the plant debris to its simplest
constituents is arrested. In the process some of
the carbon has disappeared in the form of carbon
dioxide or marsh gas, while much has been left behind
in the form of humic acid and other relatively com-
plex products, the composition of the mixture
depending on the original constituents of the moss,
on the bacteria and fungi that have acted on it, and on
the atmospheric and other conditions in which they
have done their work. The latest materials to be
altered are the woody plant tissues, but as the peaty
deposit gets covered and subjected to pressure as a
result, for instance, of the slow local sinking of the
earth's crust, atmospheric air becomes completely
excluded, fermentation sets in, the oxygen combined
with the tissues tends more and more to disappear,
and the moss then goes through the changes, be-
coming first peat, then, under the influence of time
pressure, and further bacterial action, lignite, and,
lastly, as the pressure further increases, coal. So
much at the present stage for the composition of
peat, a subject to which I shall have to return in the
chapter on the humus of the soil.
That the problem of the utilization of peat is an
important one to the world is shown conspicuously
by a glance at the extent of the deposits present in
various parts of the world. In Europe there are
believed to be 212,700 square miles of bog ; in Canada
50,000 square miles; in the United States of America
35,000 square miles; in European and Asiatic Russia
70,000 square miles. Northern Europe alone is esti-
38 THE SPIRIT OF THE SOIL
mated to consume annually about 10,000,000 tons
of peat, while each year Russia produces 4,000,000
tons, Germany 2,000,000 tons, and Holland and
Sweden each 1,000,000 tons.
These may seem brave figures, but despite them
peat is a world product little in demand. Many men
have tried to utilize it for various purposes. Great
works have time and again been set up by the side
of peat bogs ; there has been abundant activity and
enthusiasm, but the wheels of the machinery have
slackened more often than not and stopped, and the
attempt to utilize peat has in the majority of cases
been written down a failure. The fact is the more
curious when one knows the many uses to which
peat may be put, and, under certain conditions, has
been put successfully. As in humogen it is probable
that there will be a considerable demand for the raw
material, it will perhaps be of interest to consider
some of the present uses against which this new use
will have to come into competition.
The use of peat as a fuel in the districts from which
it is cut goes back to the earliest times. In the
minds of English readers it is associated chiefly with
Ireland, and the peat fire, like the jaunting-car, is
the novelty that impresses itself most obviously on
the mind of the tourist as a feature of the typically
Irish environment. In Ireland peat really does
enter into the life of the people. It has given the
peculiar acrid taste of its smoke to the whisky of the
country; it is burnt in the tumbledown cottages
scattered far away from civilization ; and when the
tourist wishes to carry away with him a memento of
PEAT AND ITS USES 39
his visit to Ireland, he usually does so by buying a
trinket carved out of the black bog oak that has been
lying for centuries preserved from the decaying
influences of climate beneath the covering of peat.
While peat is used in this crudely simple way as a
fuel in Ireland and elsewhere, there have been many
attempts made to employ it on a larger scale. One
reads of press peat, pressed peat, condensed peat,
machine -formed peat, wet-process peat, briquetted
peat, all of which represent the attempts of the
inventor to spread the utilization of peat as a fuel
over areas remote from the peat bog, but their efforts
have met with little success. Peat has a low heating
value ; special grates are required for its consumption,
and the relatively large quantity of ash makes the
handling of it a difficult matter. The experiment
has even been made of powdering the peat and
employing it in special powder burners, and it seems
that it is only because of the low price of coal that in
this form it has not become really popular. The
process of briquetting peat again is one that has
given good prospects of success. To prepare the
briquette the raw peat is treated and pressed. As a
result of the treatment a black heavy compact sub-
stance results that is pleasant to handle, and that
has a fuel value comparable with that of ordinary
bituminous coal. The fact remains, however, that
so far the briquettes have not come into public
favour. In peat coke one meets with another of
the attempts made to establish peat as a common
household fuel. On paper the scheme seems promis-
ing enough. By-products similar to those obtained
40 THE SPIRIT OF THE SOIL
from coal are obtained, and the coke itself forms a
satisfactory fuel, which in several ways is superior to
charcoal ; but the fact has to be faced that the manu-
factory producing it that seemed the most flourishing
has been forced to suspend manufacture because the
cost of preparing the coke was too high to make the
venture practicable.
Frequently the suggestion has been made that it
should be practicable to utilize the peat on the spot
as a source of power, and in Germany and Sweden
particularly several plants have been equipped for
the purpose. Excellent illuminating gas can be
obtained by heating the peat in retorts, and the
material is also suitable for making water-gas, fuel-
gas, and producer gas. There are several plants on
the market designed for the manufacture of the gas
in one or other of these forms, and the peat bogs in
Germany and Sweden have been made use of to a
considerable extent in metallurgical operations, in
brick and glass making, and in lime burning.
Unquestionably peat as a fuel has a future before
it ; the trouble at present, however, is that the price
of coal is so low that it is difficult for other sources
of power to compete against it, a fact that is perhaps
most emphatically brought out when one considers
that it is found to be less expensive to pump the
marsh waters off the land in such places as Norfolk
by coal-using steam-engines than it is to utilize
windmills for the purpose.
The utilization of peat as a source of chemical
products has attracted a considerable amount of
attention in recent years. There are processes by
PEAT AND ITS USES 41
which alcohol can be derived from peat by means of
fermentation, and large experimental plants have
been equipped and run for the purpose; but here
again it has usually been found that the returns do
not allow a sufficient profit for the manufacture to
be successfully carried on. Both nitrate and ammo-
nium sulphate have been derived from peat, and in
the latter case particularly the claims of inventors
seem to suggest that the peat might form the basis
of a profitable industry. Here, too, however, it is
only possible to say that the process is in the experi-
mental stage, and that hitherto it has been of
theoretical rather than practical interest.
Paper is another substance that can be derived
from certain varieties of peat, but the product is dark
in colour, and only suitable for cardboard or coarse
brown papers. In this instance, as in so many
others, the manufacture has not gone beyond the
experimental stage owing to the expense of reducing
the peat fibre to a condition suitable for use. The
same may be said of the attempts to utilize peat for
woven fabrics, and to form out of it a sort of artificial
wood.
To many it may come as a surprise to hear that
peat possesses absorbent, deodorizing, and anti-
septic properties, and in several tentative ways
attempts have been made to exploit them. Mat-
tresses made of peat have been constructed for
hospital use, and they have the advantage of being
light, resilient, soft, inodorous, and very cheap.
Further, American surgeons have made use of peat
purified and powdered for dressing cuts, burns, and
42 THE SPIRIT OF THE SOIL
other wounds, with excellent results. For the same
reason, and because of its mechanical texture, it is
greatly valued as a packing material.
Lastly, as is well known, peat is in considerable
demand for litter. Its value consists chiefly in the
facts that it is able to absorb far larger amounts of
moisture than any other substance used for bedding,
that it is a good deodorizer, and for a considerable
period almost entirely prevents the decomposition
of nitrogenous and other organic substances.
Further, it is springy and durable, and keeps the
feet of the animals standing on it in a perfectly
healthy condition.
Commenting on the position of peat generally,
Dr. Dachnowski writes :
" Peat can hardly be classed as a satisfactory raw
material for making any of the more complicated
products under the usual conditions existing in Ohio,
where other and established substances are already
to be had in any desired quantity and at satisfactory
prices. Moreover, these products are obtained from
peat only by large investment of capital, and in
most cases cannot be manufactured before the plant
has passed through a long experimental period,
which must be properly provided for by a consider-
able fund established for the purpose. The simple
products, peat litter, mull, mattresses, packing
material, and peat fertilizer litter, have a much
greater chance of being quickly made profitable,
because some of them are already on the market, and
present uses for which the peat is especially adapted.
Moreover, the processes of preparation are simple,
and the cost of equipment for their manufacture
with tried machinery is so low that moderate ex-
penditure will fully equip a plant to produce them,
PEAT AND ITS USES 43
and it is unnecessary to provide for a long experi-
mental development. It is apparent therefore that
the more fibrous kinds of peat, when they are found
in Ohio, may be put to a number of profitable uses,
besides making them into fuel; while the black
plastic types, which are of frequent occurrence, have
other possibilities, although they are not adapted
to the same uses for which the first may be recom-
mended."
Dr. Dachnowski's comments are of considerable
interest and importance from my present standpoint.
While they show that there are a considerable num-
ber of uses to which peat can be put, they indicate
clearly that they are not sufficiently important to
make any large demand on the world's peat resources,
and that the agriculturist who wishes to make use of
bacterized peat for the improvement of his land need
not fear that it will be necessary for him to compete
with other peat users for the raw material.
In discussing the uses of peat I have made no
reference to the possibility of its being used for its
own sake as a fertilizer for the land. Peat, as such,
is useless for the purpose. The nitrogenous and
other organic substances in it are almost insoluble,
and are not available as plant foods, while the facts
that it is acid and antiseptic render its employment
raw definitely harmful. As peat-moss manure,
however, it has been employed on the land, but it
must be used with suitable precautions. In Decem-
ber, 1911, the Journal of the Board of Agriculture
brought this out very plainly, as the result of an
experiment accidentally made at Kew Gardens.
Speaking of the litter, the Journal states: "It is
44 THE SPIRIT OF THE SOIL
neither peat nor moss as these are understood in
horticulture, and is entirely unsuited for the growth
of plants. It is imported in the form of bales,
which are broken up in the stables to be spread as
bedding in the stalls. When it becomes saturated
with urine and contains a considerable proportion
of horse -droppings, it is thrown into a heap to be
carted away. Compared with straw-made manure
this moss-litter is cheap, but is not looked upon with
favour by market gardeners. Its use at Kew has
been mainly as a top dressing for lawns and borders,
but only after it has been exposed to the air for
about six months and turned several times. It has
not been used for mixing with the soil, but this spring
some of the flower-beds were in error manured
with it. Its effect on the health and growth of the
plants which were afterwards put into these beds
for the summer was markedly deleterious. The
plants not only failed to start into growth, but many
of them weakened and died, and as this was evi-
dently due to the manure in the soil, in which the
plants were set, samples of the soil and manure were
submitted to Dr. J. A. Voelcker for analysis and
report."
The text of Dr. Voelcker's report appears in the
Journal of the Board of Agriculture. He points out
that nothing in the analysis led him to suspect the
presence of disinfectants or deodorizers, nor were
there signs of any mineral acid or the like. He
notes that market gardeners refuse to use the moss-
litter manure until it has been kept for quite two
years. He states also: " I have come to the con-
PEAT AND ITS USES 45
elusion that the ill-effects in the present case are due
to the marked acidity of the manure, this acidity
being due to organic acids in the soil and not to
mineral ones. I find in the soil (in which the manure
has been used) iron compounds present in the
ferrous — or not fully oxidized — conditions, and it
would seem to me likely that these are the result of
the liberal use of an organically acid body such as
the peat-moss, and that an unhealthy, imperfectly
oxidized condition of the soil has been brought about.
Very probably, if the manure be kept longer and
allowed to rot more thoroughly, it becomes more
aerated and oxidized, and then would not show the
ill-effects noticed. This, it seems, is the possible
explanation of what has occurred in the present
case, and it is the explanation at least which would
suggest itself to me."
In a later chapter it will be necessary to consider
the composition of peat in some detail, and to show
how, in the case of humogen, the process which takes
two years to accomplish when the peat is left in a
heap is carried out in a few days by suitable bacterial
treatment. It may perhaps be as well to insist here
that the addition of humogen to the soil is not under-
taken so much with the object of enriching the soil
with the nitrogenous and other organic compounds
contained in the peat, but that it is designed more
particularly as a medium to facilitate the growth oi
the bacteria with which it is inoculated, and to
enable them to work vigorously in changing the
nitrogen of the air into nitrogenous plant food.
CHAPTER V
FIXATION OF NITROGEN BY LEGUMINOUS PLANTS
Beneficial effect of growing leguminous plants — Liebig and the
chemical era — A fundamental error corrected by Lawes and
Gilbert — Their experiments on legumes — Pasteur, Schloesing,
and Miintz's discovery — Warrington's solution of the nitro-
gen problem for non -legumes — Hellriegel and Wilfarth's
paper — Their experiments on legumes — Behaviour of the
plants explained — Importance of bacteria — Ward's inocula-
tion of legumes — Beyerinck's Bacillus radicicola — Nobbe's
culture — Experiments in the United States and in England —
Conclusions of the Board of Agriculture — Work at King's
College — Field experiments with nitrobacterin — Successes
and failures — Unfavourable conditions — Disappointments —
Nature of benefit to be expected — The Bacillus radicicola —
Mechanism of symbiosis — Chemistry of the process —
Effect of over-rich soils — Balance between plant and bac-
teria— A trade analogy — Hopefulness of outlook.
FROM the earliest days of agriculture practical men
have recognized the fact that the fertility of the soil
was increased by the growing in it of leguminous
crops. It is only within the memory of living man,
however, that it has been possible to state definitely
what actually occurs in connection with leguminous
plants. A convenient date from which to start
tracing out the stages through which the whole
problem relating to leguminous plants has been
carried is the year 1840. It was then that the
46
FIXATION OF NITROGEN 47
German professor Liebig presented to the British
Association the famous report afterwards published
as a book on Chemistry in its Application to Agri-
culture and Physiology. By applying the exact
methods of chemistry to agriculture Liebig succeeded
in establishing that plants derive the Carbon of
their tissues from the Carbon Dioxide of the air, and
not from the Carbon compounds that may be present
in the soil. He did more than this, for he pointed
out that " the crops on a field diminish or increase
in exact proportion to the diminution or increase of
the mineral substances conveyed to it in manure."
In one essential point, however, he fell into error.
He came to regard the Ammonia of the air as analo-
gous with the Carbon dioxide in the air, and preached
the doctrine that the plants were able to derive their
nitrogenous food from the atmosphere. In the
Farmer's Magazine, for instance, he wrote :
" If the soil be suitable, if it contains a sufficient
quantity of alkalis, phosphates, and sulphates,
nothing will be wanting. The plants will derive
their Ammonia from the atmosphere as they do
Carbonic Acid."
Liebig's discoveries were of classic importance,
partly because of the valuable contribution they
made to agricultural knowledge, but still more
because of the stimulus they gave to agricultural
research along exact lines of experiment. He had
not, however, found the whole truth. His patent
manure, when tried in the field, was a failure, partly
because he presented his mineral foods to the plants
in forms unsuitable for their absorption, and partly
48 THE SPIRIT OF THE SOIL
because of his mistaken view of the way in which
plants obtained theft Nitrogen.
Lawes, the pioneer experimenter on agriculture in
England, whose work at Rothamsted had been for
some years in progress, flatly denied the accuracy of
several of Liebig's conclusions, and as a result of
further experiments conducted by himself and
Gilbert, made several important discoveries in con-
nection with mineral manures. These do not con-
cern us here ; what is of importance from our present
standpoint is that by 1855 Lawes and Gilbert had
established that —
1. The beneficial effect of fallowing lies in the
increase brought about in the available nitrogen
compounds in the soil.
2. Non - leguminous plants require a supply of
some nitrogenous compounds, nitrates and Am-
monium salts being about equally good. The amount
of Ammonia obtainable from the atmosphere is in-
sufficient for the needs of crops. Leguminous plants
behave abnormally.
The experiments had been conducted on the fol-
lowing lines: A long list of plants, leguminous and
others, had been grown in surroundings free from
Ammonia or any Nitrogen compound. The soil in
which they grew had been burnt; the air furnished
them was washed and purified, but they were sup-
plied with everything necessary in the form of
mineral foods. All but the leguminous plants
languished and died. The leguminous plants, how-
ever, were found to flourish. They assimilated large
quantities of Nitrogen into their tissues, and the soil
FIXATION OF NITROGEN 49
in which they were growing was found to become
richer and richer in nitrogen compounds.
To the chemist these results were a mystery, and
it was not until a fresh method of attack was devised
that the truth emerged.
While Liebig, Lawes, Gilbert, and others, were dis-
cussing agricultural problems purely from the
chemical standpoint, Pasteur had begun to show the
paramount importance of bacteria. It was estab-
lished by him that putrefaction and decomposition
were brought about by the action of bacteria, and
the successes he had obtained in combating terribly
serious plant diseases in France had been so sen-
sational as to attract those interested in agriculture
to the importance of bacteria. It seemed possible
that bacteria might be closely connected with the
changes going on in the soil.
The first of a series of classical experiments was
published in 1877. In that year Schloesing and
Miintz allowed some sewage water to trickle very
slowly through a filter of sand and limestone. During
the first twenty days of the experiment the Ammonia
in the sewage passed unchanged. Then it was
noticed that some of it was changed into nitrate, and
after a short time it was found that all the Ammonia
which went in at one end of the filter .was changed
to nitrate, and emerged at the other end of the filter
in the form of nitrate. If the phenomenon had been
purely a chemical one, there was a mystery as to why
the filter should be inactive for the first twenty days ;
but if it was connected with the growth of living
organisms, it was natural that time would have to
4
50 THE SPIRIT OF THE SOIL
elapse to enable them to grow. To test the accuracy
of this view Chloroform was passed through the
filter. The change of Ammonia to nitrate at once
ceased, but on removing the Chloroform and adding
a little turbid water extract of dry soil to the filter
the action started again. The experiment proved
conclusively that bacterial action was responsible for
the change.
The publication of this paper furnished Warring-
ton, who was working at Rothamsted on the problem
of soil Nitrogen, with the key to the solution. He
proved —
1. Nitrification in the soil was stopped both by
Chloroform and by Carbon bisulphide.
2. Solutions of Ammonium salts could be nitri-
fied by adding a trace of soil.
3. The change occurred in two stages, two
different bacteria being involved in the process, the
Ammonia becoming first of all nitrite (NO2) and
then nitrate (NO3).
So was solved the mystery as to how non-legu-
minous plants obtained their nitrogenous food. It
became generally (if not quite accurately) recognized
that in whatever form of manure Nitrogen might be
added to the soil, the plants got practically nothing
but nitrates as the source of their nitrogenous food.
It was nearly ten years before the problem as
affecting leguminous plants was solved. In 1886 the
classical paper clearing up the difficulty was pub-
lished by Hellriegel and Wilfarth. They grew
several series of plants in sand, adding the food con-
stituents as they desired, and they found that the
FIXATION OF NITROGEN 51
growth of non-leguminous plants was directly pro-
portional to the amount of nitrate that they supplied.
In the case of leguminous plants there was no rela-
tion between the supply of nitrate and the growth
of the plant. If nitrate was not supplied to the
leguminous plant after the seedling stages had been
passed, the growth of the plant was arrested for a
short time, and then it either died or started to grow
again and did well. Further, on analyzing the soil,
they discovered that whereas, as might have been
expected, there was always rather less nitrate in the
pots in which non-leguminous plants had been
grown than at the start of the experiment, in the
case of the pots containing the leguminous plants
the soil had been considerably enriched with nitrogen.
In three cases, for instance, the gain amounted to
0*910, 1*242, and 0*789 grammes per pot respectively.
Botanists had already noted that leguminous
plants were peculiar in the fact that their roots con-
tained swellings or nodules, and without appreciating
the bearing of the discovery, had remarked that
these swellings or nodules contained bacteria.
Hellriegel and Wilfarth, however, found in the
experiments they made in growing leguminous plants
in sterilized sand that all the plants that lived con-
tained these remarkable swellings on their roots, and
they reached at once the right conclusion that legu-
minous plants had apparently the power of obtaining
nitrogenous food material from the air because of the
bacteria harboured in their roots.
At last the great puzzle had been solved, and it
was found that the difference that seemed to mark
52 THE SPIRIT OF THE SOIL
out leguminous plants as distinct from all others was
apparent rather than real. The great generaliza-
tions, however, emerged:
1. Plants derive their nitrogenous food material
from the foods present in the soil, and not from any
gases in the air.
2. The nitrogenous plant foods present in the soil
are either directly or indirectly* derived almost
entirely from the Nitrogen of the soil air, which is
combined to form a suitable plant food by the
bacteria living in the soil.
This discovery was obviously of fundamental
importance. Botanists had hitherto regarded the
soil as a complex mixture of chemicals from which
the plants derived their food. Now, however, they
began to appreciate the fact that the earth's surface
was no inert mass of soil, but was the seat of myriads
of living organisms necessitating the closest study.
The discovery made by Hellriegel and Wilfarth
was rapidly followed up. A year after they had
announced the main facts, Marshall Ward, by careful
study of the tubercles of leguminous plants, traced
the whole process of nodule formation from the
infection of the root hairs of the plant by some soil
organism up to the formation of the mature nodule,
and showed that the tubercles could be produced at
will by the inoculation of the roots with soil infusions.
In 1888 Beyerinck isolated the organism by growing
* When such a substance as stable manure is added to the
land, the nitrogenous bodies which it contains are plant
residues, and these have, either directly or indirectly, derived
their Nitrogen substance from the Nitrogen combined by
bacteria.
--I
\ *
r >• I
I
J
FIG. 3
BACILLUS RADICICOLA. — This bacillus is found in the nodules of leguminous
plants, only lives in symbiosis, and combines the nitrogen of the soil air to
form nitrogenous food material. The beaded rod form, and also the V-
and Y-shaped groups, are characteristic.
FIG. 4
AZOIOBACTER CHROOCOCCUM is found in all fertile soils and, living by itself,
enriches the soil in nitrogenous food material available for all classes of
plants. It is through its activities that soil which is rever manured can
maintain its fertility. The trees of all virgin forests and most wood-
lands depend on it exclusively for t leir nitrogenous food. It is ovoid
in form.
FIXATION OF NITROGEN 53
it on a pure culture medium, and named it Bacillus
radicicola.
Two years later, in 1890, Prazmowski succeeded
in inoculating the roots of bean plants growing in
sterilized soils, and in obtaining luxurious growth by
simply watering the plants with a liquid culture of
the organism.
It was when this stage had been reached that the
direct commercial application of the knowledge
newly obtained first fired the imagination as a means
of enormously increasing the earth's fertility. The
enthusiasm was thoroughly justified, for those
familiar with the amazing efficiency of bacterial
action, and familiar, too, with the results obtained
when the conditions of growth could be satisfactorily
controlled, as in the hothouse, were confident that
only a little more experience was necessary for
similar results to be obtained in the field.
Professor Nobbe of Germany was the first to try
and capture the market. His method was to collect
the bacteria from various leguminous nodules, plant
them in bottles containing nutrient gelatine, and
sell them under the trade name of Nitragin. Some
of the results Nobbe obtained were satisfactory, but
the percentage of failures was so great that the
method was to a large extent discredited, just as the
imperfections of method employed with Koch's
tuberculin in the early stages resulted in the dis-
crediting of a principle thoroughly sound.
Nobbe's work had one good result, however. The
successes obtained had been such that in 1901 the
United States Department of Agriculture com-
54 THE SPIRIT OF THE SOIL
menced " a scientific investigation of the root-
nodule organism with a view of making practicable
for use in the United States the pure-culture method
of inoculation." It was not long before the causes
of Nobbe's failures became apparent. The function
of the nodule bacteria is to fix free nitrogen from the
air. When they were in such an environment as
gelatine with combined nitrogen in abundance they
became over-fed and lazy, lost their virulence, and
no longer had the power to force their way into the
roots of leguminous plants and form nodules. The
American investigators soon improved on Nobbe's
methods. They used a Nitrogen-free medium for
cultivating their bacteria, and thus increased the
Nitrogen-fixing power of the bacteria. When this
stage had been reached the bacteria were dried on
cotton-wool and distributed. In the course of the
two years, 1903 and 1904, over 12,000 packages
were sent out free to farmers in the various districts
of the United States, and the report published in
January, 1905, showed that 74 per cent, of the trials
were successful — that is, gave an increase of crop as
a result of inoculation.
These experiments aroused the interest of the
Board of Agriculture and Fisheries in this country,
and they invited the co-operation of thirteen agri-
cultural colleges and experiment stations to try
experiments with the American culture. The
Journal of the Board of Agriculture for February,
1906, however, issued a most pessimistic report as
to the results, stating that " the negative results
exceed the positive in number, both in plot experi-
FIXATION OF NITROGEN 55
ments and under agricultural conditions." The
summing up of the report was as follows :
" As a result of all the reported experiments, it
seems evident that the cultures used were not
uniform; it is not possible, however, to determine
the extent to which the failures are to be attributed
to this cause. It seems, however, from the positive
results recorded, that not only are these cultures
sometimes able to produce nodules on the roots of
plants new to a neighbourhood, but that even in
cases where the leguminous crop had been grown in
the previous year benefit may be derived from
inoculation.
"It is quite evident that the subject of plant
inoculation in this country has not yet passed the
experimental stage, and more work is required before
one can feel at all justified in recommending either
method for adoption on a field scale; nevertheless,
the positive results obtained may lead farmers to
hope that in the future benefit may be derived in
some instances at least from the treatment of the
soil, or the seed before sowing, with inoculating
materials preparatory to growing leguminous crops."
It is unfortunate that the Board of Agriculture
and Fisheries did not see its way clear to help in
carrying out the further work required, for the
results, though admittedly unsatisfactory, indicated
clearly that a great future lay before the method of
soil inoculation. Thus, in Scotland an acre of
inoculated beans yielded 3,070 pounds of beans,
against 1,800 pounds from an acre non-inoculated, a
gain of 70 per cent. In Leicestershire a half -acre plot
of treated peas yielded when threshed 108 stones ;
a half -acre plot untreated only 66 stones. At Woburn
56 THE SPIRIT OF THE SOIL
treated Melilotus gave 23 per cent, heavier crop than
untreated. At Aberdeen, " on a farm where the
soil is peaty, and clover had never grown well, the
treatment has been remarkably successful, producing
a thicker covering of clover and a much stronger
growth. The difference has increased between
October and the present time in an extraordinary
way."
Even before the Board of Agriculture Report had
appeared, in the autumn of 1905, American experi-
menters had discovered a cause of failure. The
bacteria when sent out on dried cotton-wool only
retained their vitality for a period of from six weeks
to a couple of months, a fact that in itself amply
explained the negative results obtained in many of
the experimental stations in this country. For it
was admitted that in several instances the cultures
had been kept as much as six or eight months before
being applied to the land.
While Amferica was carrying out field experiments
on this lavish scale with cultures of the Bacillus
radicicola, the attempt was being made by Professor
Bottomley in the Botanical Laboratories of King's
College, London, to clear up several points that were
obscure in the life history of the bacteria, and to
determine accurately the nature of the chemical
changes involved. When the Board of Agriculture
discontinued their field experiments he decided to
invite the co-operation of farmers, professional
growers, and others interested, to test the efficiency
of the pure cultures with which he had been working
at King's College. To send out the bacteria on
FIXATION OF NITROGEN 57
cotton-wool, as had been done in America, would
clearly have been to invite failure, and several tests
were made to find out the most suitable medium.
After many trials it was found that when the bacteria
were mixed with earth and the whole was dried, the
bacteria lived, and retained their vitality in any
case for several months, and in some instances for as
much as three years.
During the years 1906 and 1907 more than a
thousand packages of the material were distributed
throughout the country, and in over 80 per cent, of
cases the reports showed that an increase of crop
had resulted from its use.
That the results obtained justified the enthusiasm
aroused can readily be understood from the nature
of the reports received. They are given in Appen-
dix A just as they were originally published seven
years ago, but the following short quotations from
them are sufficient to prove that the radicicola
cultures showed promise of revolutionizing the
everyday practice both of horticulture and agri-
culture :
" The peas were a great success. Inoculation of
soil and seed returned a good 30 per cent, more than
only seed inoculation, and the seed inoculation
showed a good 20 per cent, better crop than the
farmyard manured peas. Inoculation in both cases
rendered a fortnight earlier marketing possible over
the manured."
" The inoculated clover was taller by 3 inches
than the uninoculated."
' The inoculated Broad Beans were up a week and
a half before those not treated, and were very much
58 THE SPIRIT OF THE SOIL
greener and more weight. Two rows inoculated,
65 yards long, gave 4J- pots. Two rows, not inocu-
lated, 65 yards long, gave 3 pots."
' The inoculated Beans were quite three weeks
earlier than the others."
" I put the inoculation liquid on about a quarter
of an acre of grass and clover as a top-dressing. In
about a week I could see an improvement, and the
clover was far higher and thicker than the rest of the
field right on until it was cut. There was double the
quantity on it, and it was the same with the after-
math; it came up the second time far thicker and
stronger than the rest of the field."
" From a quarter of an acre of peas inoculated I
picked 33f pots (42 pounds to the pot), selling them
for £7 i8s. gd. From a quarter of an acre not inocu-
lated, but dressed with i cwt. superphosphate and
\ cwt. sulphate of potash, I picked only 14 pots,
selling them for £2 5s. 6d."
From certain points of view the very success of
the results obtained proved unfortunate. Little
was known about the bacteria at the time, or of the
conditions necessary to their growth. Experience in
the form of negative results had yet to show that the
bacteria were unable to grow in acid soils, and that
in such conditions it was necessary to resort to
liming to correct the acidity ; that the bacteria would
not grow in land already rich in nitrates ; that they
were sensitive to adverse conditions of weather and
climate; that their efficiency would be impaired
either when the plant concerned was too weak, in
which case the weaker bacteria could force an
entrance into the roots, or too strong, when the roots
might succeed altogether in resisting bacterial
FIG. 5
The value of the auximones in promoting healthy growth is strikingly
illustrated above. Each of the treated plants (Primula malacoides]
received the water extract of ribth of an ounce of humogen, but
otherwise the treatment was identical. The increase of growth,
flowering, and of root development in the treated plant (on the
right) is very evident, but typical.
(Dr. Rosenheim, University of London, King's College.)
FIXATION OF NITROGEN 59
invasion. These were some of the causes that led to
disappointing negative results. There were occasions,
too, when failure resulted, because the directions for
preparing the bacterial culture on the farm were
not accurately followed. Sometimes soils were
treated that were deficient in phosphates and potash,
and naturally the bacteria were powerless to make
up for the absence of these minerals.
For these and similar reasons there were several
failures with the cultures. The feeling of disap-
pointment among growers was great, and naturally
the men who had gone to all the labour and trouble
of inoculating their seed and soil only to find no
trace of advantage came dogmatically to the con-
clusion that nitro-bacterin, as the culture was called,
was no good. Such failures were widely advertised,
and as some of them occurred at experimental
stations, growers were discouraged from making
further attempts.
At this stage of the work, however, the successes
obtained were for the time being of more importance
than the failures, for the successes proved definitely
that in England, if the conditions were such as to
favour inoculation, the following important benefits
resulted :
1. An increased yield of the leguminous crop.
2. The improvement of the land for succeeding
crops through the addition of organic nitrogen to the
soil.
3. Increase of the nitrogenous content of inocu-
lated crops, carrying with it an increase in feeding
value.
6o THE SPIRIT OF THE SOIL
4. In many cases hastened maturing of plants,
thus allowing the earlier marketing of produce with
enhanced value.
The fact that it was possible in certain conditions
to obtain such results made it plain that it was
worth while to continue working at the problem.
As will be seen in later chapters, the further work
done has led to results that at the time were un-
suspected, and that are far more important than
were dreamt of at the time. Before considering
them, however, it will be well to conclude this
chapter with a short account in view of modern
knowledge of the Bacillus radicicola in its relation to
leguminous plants.
The B. radicicola is a small rod-shaped organism
that is found widely distributed in nature. For
some reason, as yet unexplained, it is able to attack
the roots of the leguminous plants. It forces its way
into the delicate root hairs of the growing legumes,
and penetrates into the interior of the root branches.
When once it has effected an entrance it increases in
size and changes its shape, appearing sometimes as
irregular rods and at others as V or Y shaped
organisms. For its growth it requires food in the
form of sugar and mineral salts, and these it takes
from the roots of the leguminous plants which it has
invaded. There can, as will be seen presently, be
little doubt but that the leguminous plant resists
the entry of the bacillus. The bacillus, however,
forces its way in, demanding, as it were, rights of
partnership, and once it has established itself and
secured food and shelter, it offers to its host in return
Nitrogen that it can take from the air, and give to
FIXATION OF NITROGEN 61
the plant in a form in which it can absorb it . Present
knowledge does not make it possible to state in
definite chemical symbols what are the exact Nitro-
gen compounds formed. What can be seen when
the bacteria are cultivated in pure cultures is that a
slime forms round the bacteria. The mass of slime
and bacteria can be shown to consist of Carbon,
Oxygen, Hydrogen, and Nitrogen, and as the only
source of the nitrogen is the air, it can be stated defi-
nitely that the bacteria have seized the Nitrogen
from the air and combined it with Carbon, Oxygen,
and Hydrogen. It can also be stated definitely that
the nitrogen compounds so formed are such that
the plant can absorb them and build them into the
nitrogenous bodies or proteins that their tissues
require.
In the early stages of the process, as we have seen,
it is the bacteria that are the attacking party. The
leguminous plant, however, waits and takes its
revenge. The V or Y shaped bodies become more
numerous, but as the plant grows older many of them
are dissolved and absorbed. Some, however, remain
behind, and when the plant eventually dies they
migrate back into the soil and await their oppor-
tunity for invading the roots of the next crop of
leguminous plants.
If the ground in which leguminous plants are
grown is rich in nitrogen, as, for instance, as a
result of liberal treatment with well-rotted stable
manure or with nitrates, no nodules are formed on
the plant roots. A natural explanation is that the
growth of such plants is vigorous, and that their
oot hairs are strong enough to resist the attacks of
62 THE SPIRIT OF THE SOIL
the bacteria. In much the same way it has been
found that seeds may be able to resist inoculation —
this difficulty in practice can be easily overcome —
owing to a protective chemical substance which
prevents the bacteria from digesting the cell wall and
forcing an entry: a phenomenon roughly analogous
with the fact that the cells of the stomach and
intestines possess chemical substances that prevent
their being attacked by the digestive ferments pre-
pared in the alimentary canal. In such a case
inoculation is obviously useless.
From several standpoints a great deal depends on
the health and vigour of the root. As we have seen,
if the root is very vigorous the bacteria cannot enter
it, and in such conditions leguminous crops planted
in the soil, instead of enriching it in nitrogenous
bodies, would deplenish its store of Nitrogen.
Suppose, however, that one goes to the other
extreme, and that the plants are starved and feeble.
In such a case the roots can put up no resistance to
the bacteria. These will force an entry, but the
roots, instead of giving harbourage only to the most
vigorous bacteria, will admit even the weaker strains,
such, perhaps, as will be sluggish in forming nitrogen
compounds, and in consequence the plants will gain
little from their association with the bacteria. It has
even been suggested by some bacteriologists that the
just balance may be overset and the bacteria become
too strong for the plants, and the latter be unable to
insist on the former fulfilling their side of the con-
tract and giving up a fair share of the nitrogen com-
pounds that they have prepared. In such a case
FIXATION OF NITROGEN 63
the bacteria would be mere parasites, taking the
sugars and salts they required from the plants
without furnishing a corresponding value in return
in the form of nitrogenous foods.
This may seem to some a fanciful pressing of a
trade analogy, but it has its foundation in experi-
mental fact, for from time to time it has proved
beneficial to give light top-dressings of Nitrate to
new fields of alfalfa.* This would increase the
vigour and resisting power of the young plants. In
this way only vigorous bacteria would be able to
force an entry, and the ultimate fixation of nitrogen
would be greater. Heavier applications of nitrogen
would prove objectionable as the bacteria would be
altogether excluded.
Considerations such as these are both interesting
and important. They suggest why some of the
earlier experiments gave negative results, and hold
out the greatest encouragement for the future. Soil
inoculation, whether for leguminous plants alone or
for all plants, must be practised intelligently. The
conditions required for success are becoming every
day better known, and the time is not far distant
when it will be possible to state the exact degree of
benefit that can be looked for with confidence as a
result of soil inoculation in any given set of circum-
stances. Further, it is becoming every day, as a
result of the increase of knowledge, more possible so
to alter the environment as to increase the circum-
stances in which the practice of soil inoculation is
certain to prove of benefit.
* Bacteria in Relation to Country Life (Lipman) .
CHAPTER VI
HUMUS
Humus as the home of bacteria — Soil composed of mineral
debris and humus — Influence of mineral debris secondary —
Bacteria and plants and animals — The sun and food as pro-
ducers of energy — Humus as a source of energy — Life
limited by the food-supply — Mild humus and raw humus —
Their properties — Bacteria as chemical agents — Complexity
of humus — Four groups of compounds — Only one carbo-
hydrate isolated from humus — Carbohydrates and humic
bodies — Effect of boiling carbohydrates with hydrochloric
acid — Humic acid formed before humin — Difference between
natural and artificial humic acid — The difference reconciled
— No real formula for humic acid — Effect of boiling carbo-
hydrates with organic acids — Effect of heating carbo-
hydrates— Nature of humic bodies obtained — Proteins and
humic bodies — Nature of changes in formation of peat —
Causes of complexity of humic bodies.
EMPHASIS has been laid in the previous chapters on
the fact that the attention of all growers, directed
until recently on to the chemical and mechanical
aspects of the soil, has during the last few years been
focussed chiefly on the soil as the seat of changes
brought about by the bacteria that inhabit it. In
the last chapter, dealing with the fixation of nitrogen
from the soil air by leguminous plants, it was neces-
sary to refer briefly to the fixation of nitrogen by
bacteria which have no relation with leguminous
plants. These will have to be considered at length
64
HUMUS 65
in the following chapter, as it is chiefly they and
their activities that are the subject of the present
volume. Before doing so it is necessary to form a
clear idea of the non-living medium in which they
live and of its properties.
The soil from the particular standpoint which I
am considering may be regarded as a mixture of two
constituents — (i) mineral debris, and (2) decaying
organic matter or humus.
The mineral debris in the soil plays no very inter-
esting part in connection with the life of the soil
bacteria. It is in most cases only soluble with
difficulty, and, with the exception of lime, influences
bacterial life rather from a negative standpoint.
Thus, a clay soil will retain an excess of moisture
and interfere with bacterial growth ; a sandy soil, on
the other hand, by allowing excessive drainage, will
unduly parch the ground, and eventually check
bacterial activities. Conditions well known to the
practical agriculturist will bring about an acid state
of the soil, in which the bacteria will find growth
impossible. These and other conditions will be
considered in the chapter in which the practical
application of the bacterized peat or humogen is
discussed, but may be ignored here, as they may
fairly be regarded as factors superimposed on normal
conditions.
The centre of bacterial activity is the humus or
decaying organic matter in the soil. Bacteria differ
essentially from plants in that they have no mechan-
ism enabling them to derive their energy from the
rays of the sun, but, like animals, must secure it from
5
66 THE SPIRIT OF THE SOIL
the food that they absorb. This central fact is
fundamentally important to a proper understanding
of the subject. Many perhaps do not realize the
magnitude of the work done by the plants in breaking
up Carbon dioxide. The chemist in the laboratory
can only achieve it by an intense expenditure of
energy. Thus it is a common elementary experi-
ment to show that some such energetic substance
as Phosphorus must be used to decompose the gas.
The Phosphorus is placed in the Carbon dioxide
and heated, and in these conditions is able to seize
the Oxygen from the Carbon dioxide, and leave the
Carbon behind in the form of black particles.
Another experiment on which a chemical lecturer
will insist is the burning of a wood match. Once
the temperature of the match is raised to a suffi-
ciently high point it burns, the Carbon in it uniting
with the Oxygen of the air, large quantities of energy
appearing during the process as heat and light. It
is reasonable and scientifically exact to believe that
a corresponding amount of energy would have to be
supplied for the converse process to take place — •
i.e., for the Carbon dioxide of the air to be recon-
verted into the wood of the match. Yet this is what
is being done day by day quietly by the plants, the
energy required for the purpose being derived from
the rays of the sun and absorbed by means of the
green chlorophyll in the leaves.
The animal or the bacterium in taking in food is
absorbing materials which are able to give him the
vast quantities of energy he requires for his life.
From the point of view of energy there is no funda-
HUMUS 67
mental difference between the process occurring
when a wood match is burnt and that occurring when
a horse eats a meal of hay or corn. The only differ-
ences are that in the case of the match the energy is
delivered rapidly and in the form of light and heat,
while in the case of the horse it is delivered slowly
and is utilized for warmth, for locomotion, for per-
forming complex chemical reactions, and so forth.
In both cases the underlying principle obtains that
Carbon on being oxidized or degraded to form Carbon
dioxide yields energy.
Looked on in a somewhat similar way the decaying
organic matter in the soil, or humus, may fairly be
considered as a unit substance, and the soil con-
taining it regarded as a storehouse of energy. From
time immemorial gardeners and farmers have recog-
nized its value. Under the dominating influence of
chemical ideals they ignored more or less completely
the energy factor, and regarded the manuring of the
crop as an act undertaken with a view of supplying
to the plant the chemical constituents of which it
stood in need. In so doing, of course, they tacitly
accepted the value of manure, both mineral and
other, as a source of energy — for what else is food in
its varied forms ? — but they focussed their attention
on constituents necessary for plant life, and only
emphasized energy considerations so far as the direct
utilization of the sun's rays by the leaves of the
plant were concerned.
With the growing recognition of the importance
of bacteria, there has been in recent years a marked
increase in the attention paid to the nature and
68 THE SPIRIT OF THE SOIL
constitution of humus, and it may perhaps be most
convenient to consider it first rather from the
biological and physical standpoints, and then from
the point of view of its chemical constitution and
relationships.
The commonplace of natural history that the growth
of living beings is chiefly conditioned by the extent
and character of the food-supply is abundantly borne
out in the case of soil bacteria. Apart from the
organisms connected with the fixation of Nitrogen in
leguminous plants, which are only partially dependent
on decaying organic matter for their food-supply, the
growth, development, and activity of the soil bacteria
depend on the abundance and character of the humus
in the soil. It is this that provides them with the
energy they require in the form of food, which
improves the moisture and temperature conditions
of the medium in which they live, tending to keep
the latter more or less stable, and preventing violent
changes in temperature that would prove injurious
to their growth. It is only for very broad generaliza-
tions such as these that one can regard humus as a
simple substance of uniform composition.
Biologically it falls into two grand classes — the
mild humus or mull met with in arable soils and
woodland, and the raw humus found in heaths,
meadows, and swamps.
Mild humus is either neutral or alkaline in reaction,
and is formed in conditions that allow the free entry
of air, and facilitate the development of the so-called
aerobic bacteria — that is, of the bacteria that are
able to develop in the presence of oxygen. Raw
HUMUS 69
humus, on the other hand, is acid in reaction. The
conditions under which it has been formed have
largely checked the growth of bacteria, and result in
putrefaction rather than in decay. Whereas in the
former the organic material liberates Carbon dioxide
in quantity — is decomposed in fact by slow com-
bustion— the latter, acted on in the absence of air,
takes the Oxygen it needs for the oxidation of its
Carbon from the organic substance itself, and
eliminates also from the mass such gases as marsh
gas (CH4) . It is for this reason that the end-products
in the two cases are different. In mild humus
organic bodies are formed from which the Nitrogen-
fixing bacteria can derive their energy and food, and
on which, too, the plants can feed directly. In raw
humus the end-products are a mixture of com-
pounds known as Humic acid, or Humin, that
prevent the growth of bacteria, that are in fact anti-
septic, and that do not furnish the plants with food
material in a form in which they can assimilate it.
Peat, in fact, is raw humus. It not only fails to
undergo decomposition while remaining in the
swamp, but when put on the land in its raw state it
undergoes decomposition very slowly, and definitely
retards the growth of crops. It is only necessary
to contrast peat with the humus that can be
seen as a rich, dark liquid oozing out of a manure-
heap to realize the difference between the humus
rich in the substances required for plant food,
and that in which available food substances are
wanting.
In stating that great progress may be looked for
70 THE SPIRIT OF THE SOIL
in agriculture as a result of emphasizing the import-
ance of bacteria instead of restricting the outlook to
the chemical composition of the soil, it has to be
realized that from one very important point of view
agriculture must always be regarded as a purely
chemical process. It will always be possible to
express what happens when a crop has grown from
seed to mature plant, by an analysis of the completed
plant on the one hand and an estimate of substances
taken from the air and the soil on the other. So
long as the botanist or agriculturist bears in mind
that, in so doing he has not expressed the full process
it is as desirable to-day as ever it was that all
information possible should be derived from the
chemical conditions underlying growth. While it
is correct to state that one of the most important
properties of the humus is its power of enabling
the bacteria to develop in the soil, it is also well
to bear in mind that the value of the bacteria so
growing in the soil lies in the products of their
activities, which are essential for satisfactory plant
growth.
Humus, when one starts to consider it from the
chemical standpoint, is a highly complex mixture of
various compounds, which it has hitherto proved
impossible for the chemist either to separate or
satisfactorily to analyze. For very many years it
has formed the subject of keen interest and dis-
cussion. Naturally enough, perhaps, in early days
it was regarded as being of very simple composition.
De Saussure, for instance, in 1804 described it as a
' ' brown combustible powder soluble in Alkalies and
HUMUS 71
Ammonia compounds." Mulder was one of the
first in 1849 to attempt really to describe it chemic-
ally. He explained that it consisted of seven organic
compounds closely related to each other — namely,
Crenic acid, Apocrenic acid, Geic acid, Humic acid,
Humin, Ulmic acid, and Ulmin. Modern workers
would recognize the problem as being one of far
greater complexity, but fortunately the early stages
of any investigation into it are easily carried
out and understood. Few terms have to be used,
and to them it is possible to give a well-defined
meaning.
Humus, according to the modern views held as to
its structure,* can be divided somewhat artificially,
perhaps, into four chief groups of substance — Crenic
acid, soluble Humic acid, insoluble Humic acid, and
Humin. If a sample of humus is taken and ex-
tracted with alkali, a portion of it, known as Humin,
is insoluble. On treating the soluble alkaline liquid
with acid a precipitate is formed, but Crenic acid
derived from the humus remains in the liquid. If
the precipitate is boiled with alcohol, a portion of it
is soluble, soluble Humic acid, and a portion in-
soluble, insoluble Humic acid. To some extent
these bodies are not present in the original humus,
but they represent groups of bodies that are present,
and as the classification is very valuable if one
wishes to get as clear an understanding as possible
* The latter portion of this chapter is based on the paper by
Professor Bottomley in the Biochemical Journal, June, 1915,
" The Formation of Humic Bodies from Organic Substances."
Those wishing for fuller details should consult the original
paper.
72 THE SPIRIT OF THE SOIL
of the nature of humus, it may be well to set the
position out diagrammatically :
Extract humus, with alkali.
|
Alkaline solution, Acidify. Insoluble
| residue.
Acid filtrate. Precipitate, boil with alcohol.
Crenicacid. Humic acid, soluble. Humic acid, insoluble. Humin.
From the Crenic acid group and from the soluble
Humic acid group — it cannot be too often insisted
that we are dealing with groups of substances and
not with pure bodies — as many as twenty distinct
compounds have been isolated, while so far the con-
stituents of the two other groups (insoluble) have
defied chemical analysis. About the compounds so
isolated the curious fact has been recognized that
only one of them is a carbohydrate. A carbohydrate
is a compound that consists of a certain amount of
Carbon combined with Hydrogen and Oxygen in
such a proportion as would result in the formation of
water. It can be expressed generally in the formula,
CmH2nOn, where m and n are any whole numbers. In
view of the fact that a very large percentage of plant
substance consists of carbohydrates, it is curious that
they should not be represented largely in the decom-
position products of organic material.
In the course of the researches on Nitrogen-fixing
bacteria at the Botanical Laboratory in the Uni-
versity of London, King's College, it became desir-
able to try and determine what relation existed
between carbohydrates and the unknown Humic
HUMUS
73
acid and Humin groups. Exact definitions became
necessary at the outset of the research, and the
groups were therefore defined as follows. The term
Humic acid was given to substances thrown down
as brown colloid precipitates by mineral acids
from the water or alkaline extracts of humus, and
the term Humin to substances insoluble in water
and alkalies, but rendered soluble by fusing with
caustic soda or potash, from the solution of which
Humic acid can again be precipitated.
Three different kinds of sugars were taken as con-
venient carbohydrates, Laevulose, Sucrose, and Dex-
trose, and boiled under a reflux condenser with a
3 per cent, solution of Hydrochloric acid for varying
periods of time. A series of colour changes take
place, and the colourless solutions turn successively
yellow, red, and brown, and then begin to precipitate.
It was obvious at once that there were conspicuous
differences with the different carbohydrates, Lsevu-
lose and Sucrose changing rapidly, but Dextrose
going very much more slowly. This is well shown
by the following table:*
Yellow.
Red.
Brown.
Laevulose
Sucrose . . ...
Dextrose
i minute
2 minutes
ii ,,
5 minutes
8
60
8 minutes
J2 „
90
* A simple experiment illustrating this can be done by pouring
concentrated sulphuric acid on to a thick syrup of cane-sugar.
By this violent method these changes can be more or less well
observed, but once the reaction starts, it is completed almost
immediately.
74
THE SPIRIT OF THE SOIL
In each case the precipitate first formed from the
brown liquid was found to be Humic acid, and it was
not unless the reaction was continued that Humin
made its appearance. The experiment seemed to
suggest that Humic acid might be an intermediate
product between Carbohydrate and Humin. On
testing the hypothesis it was found that on boiling
the Humic acid from Laevulose with a 7*5 per cent,
solution of Hydrochloric acid for four hours, 98 per
cent, of it became Humin, while on treating Humic
acid derived from peat in the same way 3*5 per cent,
of it became Humin.
The result, while confirming the possibility of
Humic acid being a transition stage between Carbo-
hydrate and Humin, was a curious one, and suggested
a reason for the great variations between the ana-
lytical results obtained by different chemists with
peat. Further, while the Humic acid from the
sugars and that from peat were almost identical in
appearance, solubility and behaviour to alkalis,
they showed striking differences in composition.
Neglecting decimals, the analyses of the two acids
gave — *
Carbon.
Hydrogen.
Oxygen.
Humic Acid from sugar . .
Humic Acid from peat
65 per cent.
54
5 per cent.
5
30 per cent.
38 „
The authors responsible for the analysis given in
this table concluded that there must be structural
* Robertson, Irvine, and Dobson.
HUMUS 75
differences between the material and the artificial
Humic acids. Recent work, however, done by
Baumann in 1909 had shown that freshly precipi-
tated natural Humic acid possessed colloidal* prop-
erties, and especially the power of forming adsorption
compounds. Now these compounds can be removed
without much difficulty, and it seemed possible that
the differences observed between natural and arti-
ficial Humic acids might be due to impurities which
had been adsorbed by the Humic acid in the peat,
and which were not present in the artificially pro-
duced acid because it had had no opportunity of
ever becoming contaminated. It will be remembered
that it was the discrepancy noted between the weight
of the Nitrogen in the air and the Nitrogen prepared
by chemical methods which led Sir William Ramsay
to undertake the brilliant series of researches result-
ing eventually in the discovery of the rare gases of
the atmosphere. It will be seen later that the
study of the difference between natural and artificial
humic acids has led to conclusions of far greater
importance than had been suspected.
Elaborate means were taken to purify the natur-
ally produced Humic acid. Some finely divided
peat was powdered and treated with 4 per cent.
Hydrochloric acid until all soluble salts had been
extracted, and then treated with 5 per cent. Am-
monia. The filtered Ammonia solution was acidified
* A colloid is a substance possessing a very large molecule,
and, unlike most inorganic chemical compounds, is unable to
pass through an animal membrane. By adsorption is meant
the power possessed by colloids of holding other substances not
in actual combination with them, but in a very close association.
76
THE SPIRIT OF THE SOIL
with strong Hydrochloric acid, and a flocculent
brown precipitate obtained. This was filtered off,
redissolved in ammonia, reprecipitated, and washed.
The Humic acid so obtained was divided into two
portions. The first was dried in a steam oven at
100° C., while the second was purified by boiling for
an hour under a reflux condenser with absolute
alcohol. These two portions were analyzed, and the
following figures were obtained :
Carbon.
Hydrogen.
Oxygen.
Natural Humic Acid
Natural Humic Acid, after
extraction with alcohol. .
48-64
60-37
4'55
5'39
46-81
34-24
It will be noticed that after purification with
alcohol the natural Humic acid was closely com-
parable with that obtained from Dextrose, as can
be seen from the table :
Carbon.
Hydrogen.
Oxygen.
Artificial Humic Acid
Natural Humic Acid (puri-
fied . . ....
60-74
60-37
5-13
5'39
34-13
34-24
This does not mean that a real formula can be
written for Humic acid, for it is well known that the
Carbon content of Humic acid does vary with the
substances from which it has been prepared, but it
emphasizes that a very close similarity exists between
HUMUS 77
the Humic acid obtained from peat and one of the
Humic acids artificially prepared.
Now in the ordinary decomposition of cellulose it
cannot be expected that Hydrochloric acid would be
present, but as a result of decomposition a large
number of organic acids would naturally be formed,
and tests carried out with Lactic, Acetic, Propionic,
Butyric, Citric, Tartaric, and Oxalic acids on
Sucrose, Dextrose, and Laevulose, all showed that
the sugars or carbohydrates went through the same
colour changes as had been observed with Hydro-
chloric acid, and gave rise both to Humic acid and
Humin. In other words, it was demonstrated that
it was reasonable to suppose that the natural process
by which Humic acid and the Humin were formed in
peat from carbohydrates had been successfully
imitated in the laboratory.
While this work was in progress some interesting
results were obtained merely by the heating of
sugar, which are perhaps worth noting here, because
they may help to give a clear idea as to the nature
of Humic acid and Humin. It has long been known
that Sucrose fuses at a temperature of 160° C., and
is converted into a mixture of Dextrose and Laevu-
lose. If the temperature is raised to 190° C. it yields
a substance similar to the caramel of commerce,
Caramelan, and at higher temperatures it blackens,
becoming carbonized. When Sucrose was heated to
220° C. four distinct groups of substances were
formed.
(i) Water-soluble caramelan; (2) a water soluble
substance precipitated as fine particles by Hydro*
78 THE SPIRIT OF THE SOIL
chloric acid; (3) an alkali-soluble substance giving
the typical flocculent precipitate of Humic acid when
treated with Hydrochloric acid; and (4) a black
residue insoluble in water and alkalies, and giving
the typical Humin reactions. Curious differences
were found to occur when Dextrose and Laevulose
were similarly treated, but these are points of detail
that hardly concern us here. The points to which
I would call attention are — (i) that the heat -formed
Humic acids differ from the acid-formed Humic acids,
in that on being dried in a water-bath at 100° C.
they are no longer soluble in dilute alkali solution,
but are only rendered soluble on fusion with
caustic potash or soda; (2) that by heating or
by treating with acid the change to Humin is
via Humic acid; and (3) that in both cases the
general effect of the treatment is, as in Nature, to
take the elements of water out of the molecule of
carbohydrate.
Plant tissues consist chiefly of carbohydrates and
proteins. The latter are of varied composition, but
consist of Carbon, Hydrogen, Oxygen, and Nitrogen
in combination, and the Hydrogen and Oxygen may
or may not be in the proportions necessary to form
water. Similar tests to those made on sugar have
been carried out with the proteins, and it has been
found that Humic bodies are produced only in so far
as the proteins contain carbohydrate. For instance,
while a gramme of Mucin, which contains carbo-
hydrate, on boiling for eight hours with a 7*5 per
cent, solution of Hydrochloric acid, yielded
0*028 gramme of Humic acid, no Humic acid was
HUMUS 79
formed either with Tyrosine or Asparagine which
contain no carbohydrates.
It is to some extent on the basis of the above
experiments that Professor Bottomley has estab-
lished his method for introducing bacteria into the
soil. In his paper in the Biochemical Journal he
drew the following conclusions, which in view of their
important bearing on the subject of this book I am
quoting textually:
' The general result of the investigation so far,"
he writes, " has been to indicate that carbohydrates
generally and certain sugars in particular pass
through a regular series of changes when submitted
to the reactions described. It was also found that
air-dried sphagnum moss is readily acted on by
acids, with the formation of a brown, peat-like mass
from which Humic acid can be extracted.
" One hundred grammes of air -dried sphagnum
moss, when boiled for twenty-four hours with 5 per
cent, solutions of Hydrochloric, Oxalic, and Lactic
acids respectively, yielded the following results :
Humic Acid.
Hydrochloric Acid . . . . 11*7 grammes.
Oxalic Acid . . . . . . 2-3 ,,
Lactic Acid .. .. .. 1*8 ,,
" The humic substances comprising the Humic
acid and Humin groups probably pass through a
series of changes characterized by a progressive
increase of their Carbon content. In ordinary
cultivated soils these changes cannot be traced,
owing to the constant addition of fresh organic
matter and cultural operations, but in peat beds,
8o
THE SPIRIT OF THE SOIL
where the deposits remain undisturbed for many
years, the stages are indicated by the increasing
Carbon content of the Humus from varying depths.
This was shown by Detmer (1871), who gives the
following figures :
Carbon.
Hydrogen.
Oxygen.
Light brown peat, surface. .
52-14
7'°3
40-19
Brown peat, i foot. .
57'75
5H3
36-02
Dark peat, 7 feet
62-02
5*21
30-67
Black peat, 14 feet. .
64*07
5-01
26-87
" Thus, in peat bogs the carbohydrates of decaying
organic matter may possibly pass through changes
very similar to those observed when sugar is heated
to a high temperature — Sugar, Caramelan, Humic
acid, Humin, and finally Carbonization (peat coal).
The fact established by van Bemmelen (1900) that
Humic acid is a colloid body, which has the property
of uniting with certain radicles, explains the various
empirical formulae ascribed to Humic acid, and the
complex nature of Humus in general. But under-
lying this complexity there is the possibility of
finding in the series of sugar changes described above
two fairly definite groups of substances, which serve
as a basis for Humus formation, the Humic group
gradually merging into the Humin group."
CHAPTER VII
BACTERIZED PEAT: ITS PREPARATION AND GENERAL
PROPERTIES
Need for a mixed culture — Why peat was used as a medium —
Other possible media — Decomposition of peat by aerobic
bacteria — Superiority of artificial over natural methods —
Effects of decomposition — A simple experiment — Treated
peat contains fifty times as much plant food as stable
manure — Peat the ideal medium — The aerobic bacteria —
Sterilizing the peat — Bacillus radicicola, Clostridium pas--
teurianum, and Azotobacter — Conditions of growth — Symbi-
otic relationships — Inoculating the peat — Why the soil
should benefit — Effect of nitrogen fixation — Influence on
phosphates and potash — Accessory food bodies — Claims
advanced on behalf of humogen.
A CONCLUSION of supreme importance was reached
as a result of the experiments made in the Botanical
Laboratories of King's College on Bacillus radicicola,
the micro-organism responsible for the fixation of
nitrogen in connection with leguminous plants. The
discovery had been made that the bacillus, when
mixed with soil and dried, was able to retain its
vitality unimpaired certainly for a considerable
number of months, and in favourable conditions for
at least as long as three years. Unquestionably
soil, for the introduction of the bacillus, was a
medium vastly superior to the cotton used in
America. In a previous chapter I have attempted
81 6
82 THE SPIRIT OF THE SOIL
to show why it was that in several instances the
culture gave negative results when applied to the
land. The difficulties met with were not insuperable,
but as the experiments continued it became evident
that however successful a leguminous culture might
prove, it could never yield more than a fraction of
the results that might fairly be expected if bacterial
inoculation were practised from a broader outlook.
It was realized that Bacillus radicicola was only
one of several organisms connected with the work
of changing into nitrogenous plant food the nitrogen
present in the air circulating from the atmosphere
to the soil, and that the full benefit of soil inoculation
could only be obtained by supplying to the soil a
mixed culture which would contain the various
groups of bacteria acting in different ways for
the common end of supplying nitrogenous food in
soluble form — that is, in a form in which it can be
utilized by plants.
Chance to some extent decided the selection of
peat as a medium for the purpose. As a matter of
fact, however, there was not a large option. Some
substance was required that had or could be made
to yield a high percentage of soluble humus, for it
was known that it was on this that the bacteria had
to rely for their food. Farmyard manure was a
possible medium. The supply of it, however, was
diminishing; it was, and must always remain, un-
pleasant to handle, and it was objectionable because
of the host of mixed organisms it was bound to
contain. Leaf mould was objectionable on most of
the same grounds, and had the further disadvantage
BACTERIZED PEAT 83
of being very bulky to handle if it was purchased
raw, and of being very costly and difficult to obtain
in bulk if it was to be delivered already rotted. In
peat there was a substance rich in humus-forming
material, available in indefinitely large quantities,
cheap, pleasant to handle, highly concentrated as a
result of natural processes continued over immense
periods of time, varying in composition over a wide
range, and for practical purposes sterile.
In its raw state peat contains practically no soluble
humus. The nature of its deposition has been such
that free access of air has been prevented, and its
Carbon compounds (the carbohydrate, protein, etc.)
have only slowly and partially decomposed. In-
stead of the neutral or alkaline humus required as
food both by plants and bacteria, acids have been
formed, and the peat is unable to support the life
either of ordinary plants or of nitrogen-fixing
organisms. If the peat, however, is left exposed for
a considerable period, such as two years, for instance,
the long-delayed change that occurs in the case
of vegetable matter to which there is free access
of air readily takes place Carbon dioxide and
Ammonia are formed freely as a result of the action
of aerobic bacteria, and the peat slowly loses its acid
character. Soluble humus accumulates to a con-
siderable extent in the form of Ammonium humate,
and the peat which was valueless as a plant food now
contains available nitrogen compounds As with
most other natural changes, so with this, it is possible
in the laboratory, as in the factory, greatly to
accelerate it. Despite the ill-informed attitude
84 THE SPIRIT OF THE SOIL
usually adopted, a laboratory-performed change is
frequently more effective for a given purpose than
one carried out under natural conditions. In the
present case, for instance, if the peat were simply
thrown upon sandy soil, enormous quantities of it
would be lost. Much of the valuable soluble humus
would be leached out by rain, and pass deep into the
sand, or be wasted so far as the farmer is concerned
by being carried off in the drains. In the laboratory
and factory, however, it is a simple matter to control
the air-supply and the temperature so as to give
the aerobic bacteria the conditions under which they
can work best. Only the inevitable amount of
Carbon dioxide is given off and wasted. The process
throughout the mass is homogeneous, and the
reaction carried to the exact conclusion desired.
In such conditions the results obtained are amaz-
ing. In this connection there can be no question
as to the result, for it can be tested as often as the
observer cares with the greatest ease in any labora-
tory, no elaborate appliances or delay being involved.
All that is required is half a dozen test-tubes, a
couple of filters, and a little Hydrochloric acid,
some well-rotted stable manure, and samples of
treated and untreated peat. The value of the
rotted stable manure lies in its soluble content, and
the amount of it is easily gauged approximately by
the eye and accurately by the balance. Supposing
that equal weights of rotted stable manure, raw
peat, and treated peat are taken, well steeped with
equal volumes of water and filtered, the liquid from
the untreated peat is found to be almost colourless,
BACTERIZED PEAT 85
that from the stable manure is a lightish brown,
while that from the treated peat is so concentrated
that it has the appearance of being black. In other
words, the water extract of untreated peat contains
only traces of soluble humus, that from stable
manure — one of the best, if not the best, ordinary
source of humus — contains relatively little, while
that obtained from treated peat is extremely rich in
the substance. Supposing now that these three
tubes are left standing for purposes of comparison
and the experiment is repeated, we have, by con-
tinuing it a stage farther, a very simple means of
getting a more precise measure of the difference
between our three samples. By adding Hydro-
chloric acid to the filtered liquids the soluble humus,
chiefly Ammonium humate, makes its appearance in
insoluble form as a brown flocculent precipitate of
Humic acid. When Hydrochloric acid is added to
the water extract of the untreated peat scarcely any
precipitate appears. When it is added to the water
extract of the manure a precipitate forms that may
settle down to occupy J- or £ inch of the test-tubes,
but when the acid is added to the water extract of
the treated peat a closely compacted precipitate
results that may be as much as 6 or 8 inches in depth.
To get an exact measure of the food values of the
three substances it is only necessary to filter off
these precipitates, to dry and weigh them. Experi-
ment has shown that the untreated peat gives almost
zero as its value, the manure a unit weight and the
treated peat as much as fifty or eighty times that
obtained from the manure. The following are the
86
THE SPIRIT OF THE SOIL
actual figures of one of a score of experiments that
have been done somewhat on these lines, only on a
more elaborate scale. It shows the enormous pre-
ponderance of treated peat in available nitrogenous
plant food.
Soluble
Soluble
Total
Humate.
Nitrogen.
Nitrogen.
Raw peat
0-028
0-214
1-267
Bacterized peat
I5'i94
2-694
4-310
Garden soil
0*012
0-026
0-427
Fresh stable manure . .
0-433
0-291
2'533
Well-rotted stable
manure
1-460
0-439
2-848
One-year-old peat-moss
litter manure
1-050
0-826
2-587
If the object of the experiments undertaken at the
Botanical Laboratories of King's College had been
merely to find some new source of manure to replace
the supplies of stable manure, which both market
gardeners and agriculturists know are year by year
steadily shrinking, the successful conversion of
insoluble peat into a material rich in soluble plant
food comparable in value, but far less bulky than
that obtained in stable manure, would have been a
notable achievement. It is true that there would
have been nothing startling in the idea that it was
possible by means of the decomposition bacteria to
speed up the natural process which was known to
occur slowly in peat, and thus secure a valuable
fertilizer for the land. It is true also that the
chemist has been perfectly well aware that the same
BACTERIZED PEAT 87
change can be effected even more quickly than with
bacteria by treating the raw peat with alkalies, but
so far it had not occurred to anyone that peat could
be valuable as a manure, except when it had been
well rotted by natural means. Farmers and horti-
culturists would have probably long rested content
with buying the peat used in stables as bedding, and
storing it up to rot into good condition, though, as
has been done in practice, they could have hastened
the process by mixing it with lime.
The aim of those working at the problem, how-
ever, was not to discover a fertilizer, but to find a
medium in which the bacteria connected with the
fixation of nitrogen could be cultivated and put on
the land. In the peat treated with aerobic bacteria
they found such a medium, which was far superior
to anything they had hoped for. When once the peat
has been treated with these bacteria, from between
20 to 25 per cent, of it is available as soluble plant
food. To effect the change all that is necessary is
then to keep the peat moistened at a temperature of
26° C. (79° F.) for about a week. Steam can then
be forced through the mass for as long as is desirable
to insure that all organisms, bacterial or other, have
been destroyed, and the result is a sterile medium,
neutral or slightly alkaline, and suitable for the
cultivation either of plants or of bacteria.
Once a suitable medium had been found for the
growth of Nitrogen-fixing organisms, the question to
be settled was what bacteria could best be utilized
for the purpose in view. As has been seen in earlier
chapters, if the best obtainable results were to be
88 THE SPIRIT OF THE SOIL
gained, it was necessary to include two groups — the
Bacillus radicicola group, which acts only in associa-
tion with leguminous plants, and the other group
or groups that were able to fix Nitrogen while they
remained free -living in the soil. As regards the
radicicola group enough has already been said,
except for the statement that in the specially
treated peat the bacillus found a material better
suited for its needs than the old form of culture.
There was no longer any need for the farmer to
dissolve up the materials supplied him, and grow
the organisms for himself in home-made apparatus
with temperature and other conditions quite un-
satisfactory for the process. He had only to spread
the material on the land or to mix it with his seed,
or if he desired it in liquid form he could extract the
peat easily with water, and use the resulting liquid
to water the roots of his crop.
Of the other organisms connected with Nitrogen-
fixation it is necessary now to write in rather greater
detail. Experiment has shown that just as land on
which leguminous crops are grown becomes richer
in Nitrogen, so, too, there may be an increase of the
Nitrogen content of the soil in cases where the ground
has been left bare of vegetation. In such circum-
stances the increase will be comparatively slow, but
at Rothamsted it has been observed to increase in a
year by as much as 25 pounds an acre. There are
two groups of bacteria by the aid of which the
Nitrogen circulating in the soil air can be changed
into forms of nitrogenous plant food. The first is
anaerobic, working only in the absence of Oxygen ;
BACTERIZED PEAT 89
and the second aerobic, working in the presence of
Oxygen. The former of these bacterial groups was
first described by Winogradsky in 1893, and was
named by him Clostridium pasteurianum. It is a
small rod-shaped organism, and can readily be
grown in solutions containing the requisite organic
food, such as sugar and mineral salts. But nitrog-
enous material must not be present. In such cir-
cumstances, if Oxygen is absent, it develops rapidly.
It can even grow in the presence of Oxygen, provided
other bacteria are mixed with it to take up the
Oxygen from the culture. After growing for a few
days there is no difficulty in showing that the
bacteria have added appreciable quantities of com-
bined Nitrogen to the medium in which they have
been developing.
Several bacterial groups that are capable of fixing
Nitrogen in the presence of Oxygen have been
isolated. In 1901 Beyerinck described two species,
Azotobacter chroococcum and Azotobacter agilis. Three
additional species have since been described by Dr.
Lipman of the New Jersey Agricultural Experiment
Station. For the development of these bacteria a
good supply of air is essential, a fact that goes a long
way towards explaining why it is desirable for the
ground round the roots of plants to be kept well
aerated. A. chroococcum, the type with which we
are most concerned, is an egg-shaped organism with
a marked tendency to form agglomerations. It
requires for its development far less food material
than is needed by Clostridium, and flourishes best
in soil where lime is abundant. When cultivated by
go THE SPIRIT OF THE SOIL
itself a slime forms round it, the nitrogen com-
pounds either composing the whole of the slime or
constituting a large portion of it. It appears to be
able not merely to fix atmospheric Nitrogen, but also
to transform nitrogenous bodies present in the soil
that are unsuitable for plant food into available
nitrogenous foodstuffs. Curiously enough, like
radicicola, Azotobacter very readily enters into some
sort of symbiotic relationships. Thus it is fre-
quently found living in association with green algae.
The association of certain other bacteria in some
way as yet not understood appears to increase its
power for fixing nitrogen. Thus, while Azotobacter
vinelandii is able to fix more nitrogen than Azoto-
bacter beyerinckii, the output of the latter can equal
that of the former if a certain other small bacterium
is present. Commenting on this remarkable fact,
Dr. Lipman writes : " In what manner the Azotobacter
are favoured by the accompanying organisms is not
known. It is likely, however, that the latter use up
much of the Nitrogen fixed by the Azotobacter, and
that these are therefore compelled to increase their
activities. 5?
The importance of the fact in relation to bacterized
peat would seem to be considerable. When Azoto-
bacter chroococcnm is grown together with Bacillus
radicicola, Nitrogen fixation proceeds more satis-
factorily and in greater amount than if the two
organisms are grown separately. The character-
istic slime seen round Azotobacter is no longer ap-
parent, but long-continued experiment leaves no
doubt but that there is something in the nature of
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BACTERIZED PEAT 91
symbiosis between the two organisms, and that the
work of both is facilitated by the co-operation.
We are in a position now to appreciate the second
and concluding stage in the production of bacterized
peat. The treated sterilized peat, rich in organic
material that the bacteria are able to utilize, receives
a mixed culture of Bacillus radicicola and Azotobacter
chroococcum. The bacteria, being at a temperature
best suited to their growth and with an abundant
supply of the food material that they require,
multiply rapidly and permeate the mass of the peat.
When the whole peat mass is saturated, the action
is stopped by drying the peat, and the material is
ready to be applied to the seed or to the soil.
From what we have already seen, there are three
ways in which the soil might be expected to derive
benefit from the application of the peat. In the
first instance, the richness of the peat in soluble
humus should increase the richness of the soil from
the point of view of the food elements it contains.
Secondly, if leguminous plants are present, they
should derive special benefit from the fact that the
ground is being inoculated with the bacteria neces-
sary for the infection of their roots and the resulting
fixation of Nitrogen. Lastly, whatever the plants
grown, the soil should become enriched in nitrog-
enous foodstuffs available for the plants, because
the bacteria necessary for taking Nitrogen from the
air in the soil and for transforming it into nitrog-
enous food material have been added to the soil
and supplied with the exact foods which they require
for healthy growth. So much for what was
92 THE SPIRIT OF THE SOIL
expected. In a later chapter dealing with the results
obtained from the use of the peat I shall have to come
back to the subject, but in the meantime I will quote
from an article contributed by Professor Bottomley
to the Illustrated London News a short paragraph
describing the influence of the treated peat on the soil
as observed in one of many laboratory experiments :
' When ordinary soil," he wrote, " is mixed with
this inoculated peat there is a marked increase in
the Nitrogen content of the soil if the temperature
be suitable for the growth of the bacteria. A mix-
ture of 9 ounces of soil from Rothamsted and i ounce
of inoculated peat, incubated at 26° C. (79° F.) for
twenty-eight days, gave an increase of 54 milli-
grammes of Nitrogen per 100 grammes of soil — a
gain equivalent to a dressing of 28 cwt. of nitrate of
soda per acre, if the increase had been proportional
throughout an acre of soil 3 inches deep."
In the last chapter, it will be remembered, some
emphasis was laid on the peculiar colloidal properties
of Humic acid, and of its power to adsorb materials
from the surrounding medium. In the course of
experiments with the peat the apparent paradox
has been noticed that the peat enriches the soil in
the phosphates available for plant food to a far
greater extent than can be explained by the amount
of available phosphate in its substance. That it
can increase the amount of phosphate actually
present is obviously impossible, but that the treated
peat itself contains available phosphate and avail-
able potash seems clearly settled by such experi-
mental evidence as that plants have been grown and
BACTERIZED PEAT 93
have flourished in sterilized moss that has had no
other treatment than watering with the water
extract of treated peat. It would seem possible
that these substances are brought into solution, it
may be as the result of the action of the Carbon
dioxide liberated during the breaking down of the
peat, and that they are held or adsorbed by the
humate molecules in such a form as to be readily
utilizable when they are required by the plant. This
result was, of course, quite unexpected, and is a
side issue to the main object of the research; but
the value of peat is obviously greatly increased if a
result of its action is to render available to the
plants grown in soil so treated two substances
that are only second in importance to nitrogenous
food material, phosphate and potash, which were
previously present in unavailable form. While the
exact mechanism of the change remains uncertain,
the fact is that during the process of decomposition
the organic matter of the soil combines with such
bases as Potassium and Calcium to form humates.
In the words of Mr. Alfred Machen: " The practical
importance of this change lies in the fact that by
adding animal or vegetable matter to the soil we
not only improve the mechanical texture, but by
providing the necessary bacterial food and stimulus
we unlock and make available the insoluble potash
and phosphates of the soil, and give them to the
plants in the form required — viz., potassic humate
and phospho-humates. The fact that (i) plants
feed on humate compounds, and (2) that organic
matter broken down by bacterial activity in the soil
94 THE SPIRIT OF THE SOIL
produces humate from the insoluble potash and
phosphate are very important, for they point out a
way of cheaply converting the inert plant foods of the
soil into more active and available forms. Considera-
tion of these facts makes it understandable why the
application of organic manures has such good effects."
In the course of experiments made with bacterized
peat on the growth of plants some very remarkable
effects were noted. The plants which were treated
with the material exhibited a characteristically
marked root development, they frequently, almost
normally, matured at an earlier stage, and they were
generally more robust than those which had not
received the bacterized peat. When it is remem-
bered that these plants were being grown against
others which were receiving what the growers
regarded after long experience as the fertilizers best
suited to their requirements, it is clear that the
increased vigour of the plant could not be due to the
organic material known to be in the peat, nor to the
phosphates and potash that had become available,
nor even to the lavish supply of nitrogenous foods
derived from the air. The hypothesis was formed
that the treated peat might perhaps be rich in
accessory food bodies similar to the vitamines that
in recent years have been found to be essential to
animal growth. Experiments have now been in
progress on this subject for over two years, and the
accuracy of the hypothesis either in its present form,
or in some closely similar form, may be regarded as
established. As the subject is so novel, so striking,
and of such fundamental importance, certainly in
BACTERIZED PEAT 95
connection with the nutrition of plants, and perhaps
also so far as the treated peat is concerned in con-
nection with the nutrition of animals, I am reserving
it for a special chapter.
To conclude the present chapter it may perhaps be
convenient to the reader if I append a summarized
statement by Mr. Alfred Machen, who has been
closely associated with Professor Bottomley in the
later stages of the research, as to the claims that can
be made on behalf of bacterized peat or humogen.
It appears in the course of an article contributed to
the Fruit, Flower, and Vegetable Trades Journal for
June of this year, and is as follows :
" Manure has been discovered which possesses the
following remarkable properties :
i. Humogen is an entirely organic material
(humus), a large proportion of which is soluble
ammonium humate.
"2. It directly introduces into the soil the Nitro-
gen-fixing organisms, and provides the food necessary
for their rapid multiplication.
"3. During the bacterial decomposition of the
peat comparatively large quantities of ' accessory
food bodies ' are liberated. These bodies enable the
plant to utilize the food in the soil by stimulating the
natural growth activities.
"4. It is free from smell, dust, weed seeds, disease
spores, and insect pests, and is clean and pleasant to
handle.
''5. An ideal and complete liquid manure is made
by steeping in water. So efficient is this liquid that
plants will actually grow in it.
"6. The soil is made more fertile without subse-
quent dressing, owing to the continual bacterial
action."
CHAPTER VIII
VITAMINES, ACCESSORY FOOD BODIES AND
AUXIMONES
Importance of accessory food bodies — The perfect physio-
logical diet — Beriberi and milled rice — Vordermann's
contention and deficiency diseases — Experimental beri-
beri in fowls — Funk's vitamines — Their origin — Beri-
beri vitamin es and scurvy vitamines — Moore's experi-
ments on growth — Accessory food bodies and bacterized
peat — Rosenheim's experiments on the primula — Ex-
traction of accessory food bodies from peat — First experi-
ments on wheat seedlings — Effects of Silver nitrate and
Phosphotungstic acid fractions on wheat — Water culture
experiments — The same with elimination of seeds — Funk's
vitamines compared with Hop kins' s accessory food bodies
— Auximones — Tests with Azotobacter — A soil experiment
showing Nitrogen fixation — Bacteria as a test for auxi-
mones — The scum-forming organisms — Sensitiveness of
the test — Analogy with Hopkins's accessory food bodies —
Auximones in rotted manure — Leguminous plants as
sources of auximones — Nature of scum-forming organisms
— The " food of the gods " — An experiment with chicks
and a provisional deduction — The " standard bread '
agitation.
THE discovery of accessory food bodies has been
without question one of the most remarkable
advances of modern Biology. It is rather the
fashion nowadays to talk of recent discoveries
having hurried to the scrap-heap the work of earlier
generations. When the isolation of radium aston-
96
ACCESSORY FOOD BODIES 97
ished the chemists and physicists, there really were
people in plenty who believed that all the patient
endeavours of 150 years had gone by the board.
In the same way in medicine, while we say with
justice that the knowledge gained of bacteria has
revolutionized the science and art of medicine,
many of us are inclined to forget that the solid
foundations on which the art rested in the fifties still
remain established, even though the successful
nature of modern achievement has to some extent
hidden them from view.
For many long years it was an established
principle among animal physiologists that the perfect
physiological diet consisted of so many grammes of
carbohydrate, so many grammes of fat, and so many
grammes of protein, with a few necessary salts in
addition. It was believed that by increased per-
fection in the art of measurement the whole of an
animal's activities could be expressed in the form
of an energy equation, reduced for purposes of con-
venience to terms of heat. On the one side were
placed the heat units or calories contained in the
food; the other side of the equation showed how
this energy had been spent, and consisted of such
items as the residual energy value of the waste pro-
ducts of the body, the heat dissipated to the air
through the lungs and skin, the heat absorbed to
turn liquids into gases, the energy spent in work
and locomotion, and so forth. The work so done
was, and remains, valuable, but all the time physiolo-
gists had a feeling that everything could not be
explained by a consideration of energy factors.
7
g8 THE SPIRIT OF THE SOIL
Some men, as they do still, took refuge in con-
ceptions of vitalism, shelving in fact the problem as
insoluble; others are pressing on in search of fresh
material evidence to illuminate what remains
obscure. It may well be that the problem of the
living organism will never be solved by the physiolo-
gist, for as the research proceeds fresh factors are
continually bringing themselves into evidence, and
with the increase of knowledge it becomes more and
more possible to form some appreciation of the
extent of the unknown.
It was through researches undertaken on disease
that the physiologist was brought to recognize the
existence and importance of accessory food sub-
stances. Both experiment and observation had
long ago accustomed him to the idea that minute
quantities of substance might have astonishingly
important results on the welfare of the body.
Cretinism, with all the disarrangement of growth
and function associated with it, had been proved to
be conditioned by the absence of the excretions of
the thyroid gland. Starling and others had been
pressing their researches to elucidate the elaborate
chemical mechanism by which the conduct of the
body tissues is regulated, and the blood had come
to be regarded no longer as a simple liquid in which
red and white blood corpuscles floated about their
business, but as an intensely complex aggregate of
chemical substances, some of which were necessary
for the hourly needs of the body, while others were
present there on the bare chance of the emergency
arising that they were designed to meet.
ACCESSORY FOOD BODIES 99
Since the year 1896, when Vordermann put for-
ward the theory that beriberi occurred after the
long-continued use of milled rice — that is, of rice
from which the outer layers of the grain had been
artificially removed — a whole group of diseases has
come to be recognized under the common class name
of " deficiency diseases/' They comprise beriberi,
scurvy, and its congeners, pellagra, and possibly
rickets, tetany, osteomalacia, and sprue. Vorder-
mann's view was not long in receiving confirmation,
and the further fact was soon noted that persons
whose diet consisted of unmilled rice — that is, of
rice which retained its outer layers — were exempt
from the disease. The more exact method of
experiment was at once introduced to supplement
observation. Eykman, attempting to produce the
disease in fowls, fed some birds purely on polished
rice. They rapidly lost weight and developed
neuritis (polyneuritis gallinarum). Birds fed on
whole grain rice developed no such disease. The
outbreak of the disease was prevented by adding the
rice-polishings (the pericarp of the grain) to the diet,
and even when the disease was established it could
be cured by administering a water extract of the
rice-polishings. It had in fact been shown experi-
mentally how the disease could be brought on in
fowls, and also how it could be cured.
Casimir Funk then attacked the problem chemic-
ally, and after a series of investigations he succeeded
in isolating a substance from the alcoholic extract of
rice-polishings, which appeared as colourless, needle-
shaped crystals, and was markedly valuable for
ioo THE SPIRIT OF THE SOIL
curing experimental beriberi. Its formula is not
definitely known, but it is a nitrogenous substance,
appears to be a pyrimidine base, and probably exists
in food as a constituent of nucleic acid. Of this
substance Dr. Watson-Wemyss, in an article on
" A Summary of Recent Work on Vitamines," pub-
lished in the Edinburgh Medical Journal for last
March, writes:
" As a result of this valuable work, the prevention
and cure of beriberi came to rest for the first time on
a scientific basis. Funk's vitamine has been proved
to be the most powerful and rapid remedy we
possess in beriberi. It is present in food in such
minute quantities that simple dietetic treatment of
the disease brings about recovery very slowly, and
the difficulty of obtaining isolated vitamine, together
with its expense, make its general use at present
impossible. It is hoped that it may prove possible
to produce Funk's vitamine synthetically."
Once this new line of research was suggested to
workers, it was soon found that vitamines were
widely distributed both in the animal and vegetable
kingdom. Yeast, milk, yolk of eggs, meat, wheat,
oats, and barley, have all been shown to contain
them. They are not identical in character. While,
for instance, dried corn only contains beriberi
vitamine, scurvy vitamine also appears as soon as
the corn begins to germinate. Fresh-growing plants,
potatoes, juicy fruits, and vegetables, are rich in
scurvy vitamines, but they disappear on drying or
on heating to 100° C. Beriberi vitamine resists
drying, and is also more resistant to heat. A point
requiring emphasis at this stage is the minute
ACCESSORY FOOD BODIES 101
quantity of vitamine that is present. In rice, for
instance, only the ten-thousandth part of the rice
consists of vitamine, a fact that suggests that the
action of vitamines is in some way comparable with
that of hormones and the secretions of the ductless
glands.
It has long been recognized that scurvy is a disease
conditioned by the absence of fresh food, and that
if fresh food is obtainable the disease yields rapidly
to treatment. Sea experience of long standing
has proved the efficiency of lime-juice in its treat-
ment, and Funk has shown both that lime-juice is
rich in scurvy vitamine, and that the acidity in its
composition helps to increase its stability. While
scurvy and beriberi are similar, there seems to be no
doubt that they are different diseases, caused by the
absence of different vitamines from the diet, for
whereas scurvy vitamine by itself can prevent both
beriberi and scurvy, beriberi vitamine will prevent
only beriberi, and will not affect scurvy.
For those interested in the subject of vitamines
there is already a long literature available, and no
useful purpose would be served here by further
considering the relation between vitamines and
other diseases. Reference, however, must be made
to the experiments conducted by Benjamin Moore
and others, on the relations between vitamines and
healthy growth. On feeding young rats with a
diet of white bread growth was very soon arrested,
whereas they flourished on a diet of wholemeal bread.
The experiment had many interesting features.
It showed, for instance, how the vitamine-starved
102 THE SPIRIT OF THE SOIL
animals recovered when their diet of white bread
was replaced by wholemeal bread. To describe it
in detail would take up too much space, and to do
so is the less necessary because it formed the basis
of the campaign instituted a few years ago in favour
of " standard bread." The fact that I wish to
emphasize is that vitamines are as essential to
growth as they are to health ; in fact they are more
so, as in diet where they are abundant the normal
rate of growth is stimulated. So much is this the
case that it has even been suggested that they may
be responsible for tumour growth, and that the
formation of tumours might be checked by the
elimination from the diet of the substances exciting
growth.
In the course of the experiments made with
bacterized peat or humogen some very surprising
results were obtained. In the first instance, in a
whole series of experiments conducted at Kew
Gardens and at the Chelsea Physic Garden during
the summer of 1913, on various pot plants — wheat,
barley, oats, maize, salvia, fuchsia, carnation,
primula, etc. — it became evident that the bacterized
peat possessed a certain growth-stimulating property
that could not be accounted for by any known
manurial constituents present . Further experiments
showed that the stimulating substance was soluble
in water and effective in very minute quantities.
Dr. Rosenheim of King's College, in an experiment
with seedlings of Primula malacoides, potted up in
loam, leaf mould, and sand, found that plants
watered twice with the water extract of only
ACCESSORY FOOD BODIES 103
o'i8 gramme of bacterized peat were after six weeks'
growth double the size of similar untreated plants,
and it was noted that flower production and root
development were promoted equally with increase
of foliage. In view of what was then known as to
the effect of vitamines on the growth of animals and
on their health, it was decided as a preliminary
experiment to follow the method adopted by Cooper
and Funk for the isolation of beriberi vitamine.
A considerable quantity of bacterized peat was
extracted with absolute alcohol in a shaking machine
for three hours, and the extract was filtered off and
evaporated to dryness in vacuo. The residue was
taken up in distilled water, 'filtered, and to the filtrate
Sulphuric acid was added until the concentration of
the latter reached 5 per cent. A slight precipitate
of Humic acid was filtered off, and to the filtrate an
excess of a 30 per cent, solution of Phosphotungstic
acid was added. The whole was then left to stand
overnight, when the liquid was decanted off through
a filter, the precipitate repeatedly washed with a
5 per cent, solution of Sulphuric acid, and finally
decomposed with an excess of Baryta. The liquid
was filtered off from the precipitate of Barium
phosphotungstate, and the filtrate, freed from the
last traces of Baryta by means of a very dilute
solution of Sulphuric acid, was evaporated to dryness
in vacuo. From 7 kilogrammes of bacterized peat
the amount of dry substance thus obtained amounted
to 12*0096 grammes. For purposes of testing, this
dried residue was dissolved in such a way that the
amount extracted from 10 grammes of the original
104
THE SPIRIT OF THE SOIL
peat should be contained in a litre of water. In
other words, the proportion of the dry Phospho-
tungstic acid fraction in the final solution employed
consisted of 17 parts per 1,000,000.
Wheat seedlings were the first plants selected for
trial. Nine pots were taken, filled with sand, and
divided into groups of three. Ten wheat seeds were
planted in each pot. Three separate solutions were
made up. Each of these contained Nitrogen, Phos-
phate, and Potash in the ratio of 400, 200, and
1,200 parts per 1,000,000 respectively. The first
solution was then left as such ; to the second was
added the alcoholic extract from 10 grammes of peat
per litre of solution, while the third received instead
(in addition, of course, to the Ammonia, Phosphate,
and Potash) 17 parts per 1,000,000 of the dry sub-
stance obtained from the Phosphotungstic fraction.
Each week after sowing each pot received 100 c.c.
of solution. At the end of the period the plants
were uprooted, washed, dried, and weighed. The
results were as follow :
Weight of
Increase
Series.
Thirty
over
Plants.
Series i.
Grammes.
Per Cent.
i . Complete food solution
11-94
2. Complete food solution plus alco-
holic solution of peat
14-46
2I-I
3. Complete food solution plus Phos-
photungstic fraction
I5'45
29H
This experiment indicated clearly that the sub-
stance in bacterized peat, which had proved its
ACCESSORY FOOD BODIES 105
efficiency in stimulating plant growth, was also
precipitated by Phosphotungstic acid, and that the
Phosphotungstic acid fraction was quite as effective
as the original alcoholic extract of the peat. Further,
some confirmation was given to the hypothesis that
the peat contained bodies similar in action to
vitamines.
Funk found that on treating his Phosphotungstic
acid fraction with Silver nitrate he had been able to
obtain his vitamines in crystalline form. To deter-
mine, therefore, how far the growth stimulant in
bacterized peat resembled the vitamines, the Phos-
photungstic acid fraction of the peat was treated
similarly. It was decomposed as described above
with Baryta, and to the filtrate from the Barium
salt Silver nitrate was added until no further pre-
cipitate was produced. The brownish precipitate
was filtered off, well washed, suspended in dilute
Sulphuric acid, and decomposed with Sulphuretted
hydrogen. The nitrate from the Silver sulphide
was then exactly neutralized with Baryta, the clear
liquid filtered off from the precipitate of Barium
sulphate, and evaporated to dryness in vacuo. The
weight of dry substance obtained from the Silver
fraction from 7 kilogrammes of bacterized peat
amounted to 0-2452 gramme, and as this also was
made up into a solution so that a litre of it should
contain the silver fraction from 10 grammes of
peat, the solution contained the Silver fraction to
the amount of 0-35 part per 1,000,000 — i.e., approxi-
mately i part per 3,000,000.
To test the efficiency of this Silver extract three
io6
THE SPIRIT OF THE SOIL
series of trials were made. Nine pots in all were
taken, and 15 grains of wheat were planted in each
in sand. All nine pots received Ammonia, Phos-
phate, and Potash, as in the previous experiment.
The first series had this alone, the second series also
received some 17 per 1,000,000 solution of the
Phosphotungstic acid extract, while the third was
given some of the 0*35 per 1,000,000 solution of the
Silver nitrate extract. As before, the plants were
first treated a week after planting, and then each pot
received 100 c.c. of its food solution once a week.
At the end of the seventh week the results after
drying were as follow :
Gross
Series.
Weight
of Forty-
Five
Increase
over
Series i.
Dry
Weight.
Increase
over
Series i.
Plants.
Grammes.
Per Cent.
Grammes.
Per Cent.
i. Complete food
64'5
—
13-3480
—
2. Complete food
96-8
50
16-3818
22-7
plus Phospho-
tungstic frac-
tion
3. Complete food
96*5
49-6
15-7148
17-7
plus Silver ni-
trate fraction
As this experiment showed that the silver nitrate
extract gave results comparable with those obtained
with the Phosphotungstic acid precipitate, it was
decided further to try the experiment of growing
wheat seedlings in water culture. Two sets of
eighteen similar seedlings were selected, each set
being originally of equal weight — 473 grammes.
ACCESSORY FOOD BODIES
107
The first set were distributed among three bottles,
each having a capacity of 200 c.c. The bottles were
filled with physiologically pure water, to which the
pure salts necessary for Detmer's nutrient solution —
Ammonia 400, Phosphate 200, and Potash 1,220,
parts per 1,000,000 — were added. The second set
were grown in a solution precisely similar, except
that o'35 parts per 1,000,000 of the Silver nitrate
fraction of treated peat extract had been added.
The bottles were aerated daily, and the solutions
changed twice a week. Every sixteen or seventeen
days the plants were removed, dried, and weighed.
The results obtained were as follow :
Series.*
Weight of Sets of Eighteen
Plants.
Gain or Loss
on Original
Weight.
Grammes.
Per Cent.
i. Pure food solu-
Original weight . . 4-73
tion
After sixteen days 5*42
+ 14-7
After further seven- 5-29
+ H-8
teen days
Ditto .. .. 4-33
-8-4
2 . Pure food solu-
Original weight . . 4*73
tion plus
After sixteen days 5-57
+ 17-7
Silver nitrate
After further seven- 6-65
+ 40-6
fraction
teen days
Ditto . . . . 7-33
+ 54*9
The distinction between these two experiments is
brought out strikingly in the following diagram,
where the weights of the two series of plants are
* The poor growth of the seedlings in this series is explained
by the fact that the experiment was made early in the year,
when the plants obtained very little sunshine.
io8
THE SPIRIT OF THE SOIL
plotted against time, the dotted line showing the
plants that had no Silver extract, and the unbroken
line those which received the extract:
8-0
7-0
J6-o
4-0,
10 zo 30 -i.o
Time in Ua.i;5
This experiment, particularly when taken in con-
junction with the previous ones and others, proves
conclusively that bacterized peat contains a sub-
stance or substances which stimulate the growth of
the plant and enable it to utilize the normal food
constituents supplied to it. In nature the need
is doubtless supplied by the decaying organic
matter in the soil.
As has been pointed out above, anti-scorbutic
vitamine is not present, so far as can be ascertained,
in dry seeds, but it makes its appearance two or
three days after the young roots have begun to show,
and extracts from them have proved as effective as
ACCESSORY FOOD BODIES
109
extracts of green vegetables in the treatment of
scurvy. The hypothesis was suggested that special
growth substances were formed during germination,
which enabled the young embryo to utilize the food
material present in the seed. To test this it was
decided to remove the source of these growth sub-
stances by cutting off the seed as soon as possible
after germination, as in that case the addition of
food substances would have a much more marked
effect. For the experiment two series of wheat
seedlings were taken at a rather earlier age than in
the previous experiment. Before removal of the
seeds both sets weighed 3*97 grammes, and after
removal of the seeds 3*2 and 3*17 grammes respect-
ively. Both were fed on Detmer's solution, but the
second set also received Silver nitrate fraction
exactly as before. The results, which in this case
were even more striking, were as follow:
Series.
Weight of Sets of Eighteen
Plants.
Gain or Loss
in Weight.
Grammes.
Per Cent.
i. Complete food
Original weight . . 3-20
solution
Weight after sixteen 3*37
+ 5'3
days
After further seven- 3-20
O'O
teen days
After further seven- 2-85
— 10-9
teen days
2. Complete food
Original weight .. 3-17
solution plus
After sixteen days . . 3-63
+ r4'5
Silver nitrate
After further seven- 4-29
+ 35'3
fraction
teen days
After further seven- 5-05
+ 59'3
teen days
no
THE SPIRIT OF THE SOIL
When the variation in weight is plotted as before
against time in days, the effect of the Silver nitrate
extract which, it will be remembered, was added to
the extent of only about i part in 3,000,000, is
most remarkably emphasized. As before, the dotted
line represents the growth of the plants fed on pure
culture, the unbroken line that of the plants supplied
with Silver nitrate extract of treated peat.
I 2fc
~/\
3P 40
10 20
Time
In view of the very slight increase of growth made
by the untreated plants, the assumption seems
justified that during germination certain substances
are developed which enable the embryo to utilize
the food material present in the seed, and that these
substances can be replaced in whole or in part by
the Silver fraction from an extract of bacterized
peat.
ACCESSORY FOOD BODIES in
As we shall see in a later chapter, these experi-
ments do not stand alone. They are confirmed not
only by other experiments definitely undertaken to
test the effect of the Phosphotungstic and Silver
nitrate fractions, but the whole series of the experi-
ments made with the treated peat becomes intelli-
gible when considered in relation to the accessory
food bodies.
In describing the results obtained it has seemed
simpler so far to draw only a slight distinction
between the vitamines, as described by Funk, and
the accessory food substances, as described by
Hopkins. There is a close similarity between the
two classes of bodies, in that both are prepared by
means of Phosphotungstic acid and Silver nitrate
from such substances as the husk of grain, yeast,
egg-yolk, milk, and so forth. There are, however,
certain differences. Thus, for instance, whereas the
vitamines of Funk appear to be in the nature of a
pyrimidine base, in the experiments made by Hop-
kins it was insisted that the bodies used were free
from amino-acids, purine and pyrimidine bases. It
should be noted also that, like Hopkins's bodies, the
plant accessory substances are resistant to heat.
This is shown by the fact that after the Phospho-
tungstic extract from bacterized peat had been
treated in an autoclave at 134° C. for half an hour,
it still gave the characteristic scum reaction (vide
later this chapter) . At present analytical difficulties
make it unwise to dogmatize on this point. What
has to be emphasized is that the treated peat con-
tains substances which are able to promote growth
H2 THE SPIRIT OF THE SOIL
on lines similar to those promoted both by the
vitamines of Funk and the accessory food bodies of
Hopkins. And it should also be stated that, in the
opinion of Professor Bottomley and his co-workers,
the substances with which he is dealing are more
closely related to the accessory food bodies of
Hopkins than to the vitamines of Funk.
When Professor Bottomley first called attention
to the existence of these substances in peat, he
stated that further work was being undertaken with
a view of clearing up the nature of the substances
involved, and of defining their properties. While
the present volume was in course of preparation a
further paper was published in the Proceedings of the
Royal Society, and in it he describes the bodies under
the new term of auximones (from avgi/mos, promoting
growth) .
While the experiments described above were very
necessary to establish conviction, they had the great
drawback that long periods were required for carry-
ing them out. The delay involved in order to test
whether or not a given solution contained auximones
was considerable, five or seven weeks being required
to enable the plants tested to grow sufficiently to
put the matter beyond dispute. It is clear that
there would be an immense saving of time if the
same result could be obtained by treating rapidly
growing bacteria with the substance, and further it
was obviously of great importance from the stand-
point of the main research to know what influence,
if any, the auximones had on the growth of the
nitrogen-fixing organisms. Azotobacter chroococcum
ACCESSORY FOOD BODIES 113
was used for the experiment. Nine flasks were
taken and divided into sets of three. The same
culture solutions were placed in all three flasks — •
i gramme of Mannite, 0-2 gramme of Di-potassium
phosphate (K2HPO4), 0-02 gramme Magnesium sul-
phate (MgSO4), and 0*2 gramme Calcium carbonate
(CaCO3). The first three flasks had nothing in
addition, the second three received 0-00017 gramme
of the Phosphotungstic acid fraction — that is, the
amount obtained from i gramme of treated peat —
and the third set received a corresponding fraction
of the Silver nitrate fraction, the amount being
0-000035 gramme. Two flasks were sterilized to act
as a control. At the end of ten days no nitrogen
had been fixed in the sterilized flasks, 3-9 milli-
grammes had been fixed by the first series, 9-7 milli-
grammes by the second, and 10-4 milligrammes by
the third.
In view of the encouraging results obtained in
these experiments it was decided to 'ascertain more
definitely how far liquid cultures of nitrifying
organisms* could be used as a test for the auximones.
A culture was originally obtained by incubating
garden soil in Winogradsky's medium. Two sub-
cultures were taken from this initial culture, and
eighteen flasks were filled with pure uninoculated
culture solution (Winogradsky's). These were all
inoculated with material from the second sub-
culture. The first series received nothing in ad-
dition, each flask of the second series received
* These are organisms which have the property of converting
Ammonium salts into nitrates.
8
H4 THE SPIRIT OF THE SOIL
the Phosphotungstic acid fraction derived from
i gramme of the treated peat, while each flask of the
third received the Silver nitrate fraction from
i gramme of the treated peat. Incubation was
carried on at 26° C., and at the end of forty-eight
hours no scum had formed on the flasks which had
received no auximone, but nitrification had pro-
ceeded at a normal rate. Both sets of flasks that
had received auximones showed scum, but no
nitrification. Only two interpretations of these
results were possible: either the subculture fur-
nished a satisfactory test for auximones, or scum-
forming organisms had been introduced with the
auximones. To test this possibility a flask contain-
ing a subculture was incubated at 26° C. for four
days with no result. One half of this culture was
sterilized by heating in an autoclave for half an hour
at 160° C. To this and to the unsterilized half
the Phosphotungstic acid fraction derived from
i gramme of peat was added, and the two flasks
were incubated for three days at 26° C. The un-
sterilized flask contained a thick layer of scum,
while the sterilized flask had none. The explanation
was that the scum-forming organism is present in
soil cultures, but that the formation of the scum in
this medium is due to the presence of the auximone.
This experiment was several times repeated, and
the scum organism was found in each of several soils
tested. Under the microscope it proved to consist of a
mixture of beaded rod forms and spindle-shaped forms
Further experiments emphasized the amazing
sensitiveness of this bacterial test to the Silver
ACCESSORY FOOD BODIES 115
extract. To quote one of the experiments: Six
flasks, A to F, were taken and filled with 100 c.c.
of normal culture solution. To the first nothing
was added, but to the others decreasing amounts of
Silver nitrate extract. The quantities used and
the results obtained on incubation are shown in the
following table :
Parts per Million of
Silver Nitrate Ex-
Result.
tract added.
A. 100 c.c. culture
solution
0
None
B. Ditto . .
4-0000
Extremely thick
scum
C. Ditto ..
2-1000
Thick scum
D. Ditto . .
0-3500
Moderate scum
E. Ditto . .
0-0070
Fair scum
F. Ditto ..
0-0007
No appreciable re-
sult
In other words, when the Silver nitrate extract was
added to the amazingly small extent of i part in
15,000,000 an appreciable result was obtained.
Tests were made with a large number of other
organic substances to see whether the scum would
be formed in their presence. The result in every
case was negative until 100 parts per 1,000,000 were
added. Even then the characteristic scum was not ob-
tained, as the whole liquid was found to turn cloudy.
Further comparative tests were made with the
accessory food bodies that had been found to give
results on animals. When they were derived from
germinated wheat, dry wheat, peas, or yeast, the
n6 THE SPIRIT OF THE SOIL
scum organisms made their appearance. They did
not appear when the accessory food bodies were
derived from dry maize or dry peas. It seems evi-
dent that these scum-forming organisms are able to
serve as a satisfactory test both for auximones and
for the accessory food bodies of Hopkins.
Tests were also undertaken with fresh and rotted
manures. The result with these was that it was
found that the quantity of auximones present
increased with the progressive decomposition of the
organic matter of manure. The amount of it was
relatively small. In two-year-old rotted manure,
compared as against bacterized peat, a better scum
was obtained with the fraction from ^ gramme of
peat than with 10 grammes of the manure.
A source from which the auximones can readily
be derived is the leguminous plant. Thus the
Phosphotungstic acid fraction derived from
•jV gramme of bean nodules gave a very thin film of
scum. The fraction from ¥\ gramme of bean root
gave a fair growth, while with TV gramme a good
growth was obtained. When, however, beans were
grown in sterilized sand without the formation of
nodules no scum at all appeared, even though the
extract of TV gramme of root was used.
As regards the scum-forming organisms used for
the test, it may be noted that they require no organic
Carbon, but, like the nitrifying organisms and the
sulphur and iron bacteria, they are able to assimilate
Carbon dioxide by chemo-synthesis. They are
unable to live on nitrates, but must derive their
Nitrogen from an Ammonium salt.
ACCESSORY FOOD BODIES 117
I have dealt in this chapter with the auximones
at greater length and in fuller detail than some
readers may think that the subject warrants.
I make no excuse for so doing, as there is a possi-
bility that in the auximones derived from bacterized
peat we may have a substance of enormous value.
Wells, in his book of brilliant imagination, The Food
of the Gods, galvanized the public into an appreciation
of the meaning of vitamines. In treating the subject
he took the full licence of the novelist, and he would
doubtless be the last to suggest that by vitamines
or any other product it would be possible to upset
the unknown factors that determine the limits of
the growth of various species. Auximones will
never threaten the world with the menace that he
so graphically painted, but it is a fact that they do
aid plants to attain their fullest normal growth, and
it may prove to be a fact that they will prove
valuable in diseases of malnutrition. A preliminary
experiment, to which too much importance must
not be attached, has already been carried out at
King's College. Some chicks were taken straight
from the egg. One batch of them were fed on a
physiologically complete diet, and all naturally
developed poly neuritis gallinarum and died. The
other batch in addition to this diet also received
Phosphotungstic acid extract. They died also, but
later, and of ordinary chicken diseases. The details
of the experiment have not been published, and I am
mentioning it here rather in the hope of attracting
physiologists to undertake a research that seems as
if it might yield valuable results than as stating a
n8 THE SPIRIT OF THE SOIL
conclusion. If further experiments were to prove
that either auximones themselves, or auximones sub-
jected to some further treatment, were able to act
similarly to Hopkins's accessory food bodies, or to
Funk's vit amines, it would no longer be necessary
to say as I did, quoting Dr. Watson- Wemyss at the
outset of the chapter: " The difficulty of obtaining
isolated vitamines, together with its expense, make
its general use at present impossible."
The subject is one of proved general interest, as
was shown by the public notice that was taken of the
recent agitation on the subject of standard bread.
As in most public agitations, there were occasions
when the truth was lost sight of, when a proved fact
was applied more widely than was scientifically
justified, but the fact stood behind the exaggerations
that at times threatened to conceal it, and has
become part of the stock of common knowledge.
Such harm as resulted was trivial, and only good
can come of the general recognition of the fact that
without vitamines and without accessory food bodies
it is impossible for either plant or animal to be
satisfactorily nourished.
CHAPTER IX
ELEMENTARY CONCEPTIONS OF CHEMISTRY IN
RELATION TO THE SOIL
Difficulties of chemistry — The elements and their symbols — •
Atoms — Mixtures and compounds — Molecules — The formula
and the equation — Affinities — Grouping in the molecule —
The structural formula — Acids, neutrals, and bases — The
COOH group — Series of acids— Seventeen possible acids
with one formula — Neutralization of acids — Oxidation —
Reduction — Hydration — Dehydration — Ammonia — Carbo-
hydrates, proteins, fats, and amides.
FEW subjects present such impenetrable difficulties
to those who have not made some sort of a set study
of it as Chemistry. Range through the Arts and
Sciences as you will, and the subject-matter of them
obtrudes itself on your everyday life. Zoology
seems simple and intelligible to those who have not
studied it, because such people think of it in terms of
the animals with which they are familiar. Our
everyday knowledge of plants makes all of us some-
what of amateur botanists. The man who can
recognize the Great Bear and a half-dozen of the
constellations feels confident that if he set his mind
to it he could become an astronomer. The bicyclist
imagines himself to be, and to some extent is, an
engineer. Experience of roads and soils makes most
men in a way geologists. Electric light and motor-
120 THE SPIRIT OF THE SOIL
ing have taught men something of electricity.
When the untaught man, however, finds himself
confronted with chemistry, he is apt to feel himself
in a strange world with no means of determining his
bearings. He has seldom been brought face to face
with the elements of which chemistry deals. The
air he breathes is not only a mixture of Oxygen,
Nitrogen, water vapour, and Carbon dioxide, but he
finds that it is a storehouse of half a dozen of the
so-called rare gases. Iron, the metal he is perhaps
most familiar with, he learns, has Carbon in com-
bination with it, and by the addition of traces of
other elements may change its properties and
develop astounding degrees of hardness. The gold,
silver, and copper coins that he has been wont to
regard as pure are each and all of them alloys. Nor
is this all. The first book that he opens on the
subject bristles with an apparently infinite number
of mysterious symbols. Figures are scattered about
among them, some on the line and some beneath it,
and if he chances to light on the simplest calcula-
tion he sees it at once stretching to four places of
decimals.
For these reasons I am including in this volume a
short chapter on the chemistry of the soil so far as
we are concerned with it in connection with Nitrogen
fixation, in the hope that it may help those who have
no knowledge of the subject to get a clearer appre-
ciation of the problems involved.
Despite the complexity of nature as we see it
around us, the world contains only a few elementary
substances, known as elements. They are some
SOME CHEMICAL CONCEPTS
121
eighty in number, and only a few of them are widely
distributed. About a score of them are concerned
with the life of man and animals. These substances,
however, are found combined in all sorts of different
ways, and to study them intelligently it is necessary
to know exactly how they are built up. Take, for
instance, such a substance as starch. A single grain
or molecule of starch may be considered without
serious error from our standpoint as containing
6 unit grains or atoms of Carbon, 10 unit grains or
atoms of Hydrogen, and 5 unit grains or atoms of
Oxygen. If 2 unit grains or atoms of Hydrogen,
and i unit grain or atom of Oxygen are added to it,
the starch becomes sugar. All this clumsy state-
ment is stated in the language of the chemist in the
simple equation :
C6H1005+H20 = C6H1206.
The mysterious symbols of chemistry are in most
cases the first letter or the first two letters of the
name of the element. Thus, Carbon is written C,
and Calcium, to differentiate from it, Ca. In
some instances the symbols are derived from the
Latin names. Thus, Iron (Ferrum), Fe, etc. The
elements with which we are concerned in agriculture
(with their symbols) are the following :
Carbon
C
Sulphur
S
Hydrogen
H
Calcium
Ca
Oxygen
O
Magnesium
Mg
Nitrogen
N
Iron . .
Fe
Phosphorus
P
Potassium
K
Sodium
Ma
Copper
Cu
Chlorine
Cl
Aluminium
Al
Silicon
Si
Manganese
Mn
Lithium
Li
Zinc. .
Zn
122 THE SPIRIT OF THE SOIL
Experiment has proved that any given weight of
an elementary substance consists of a certain number
of ultimate particles or atoms of substance. One
may conceive, for instance, of a speck of Carbon
enormously magnified. In such a case one could — •
to assist the imagination — regard it as consisting of
myriads and myriads of round black grains, each of
them the exact replica of the others. Each of these
grains would be an atom of Carbon. For the pur-
poses of general chemistry one may say that these
atoms are indivisible.
The enormous majority of substances, all, in fact,
except the elements themselves, are either mixtures
or compounds. In a mixture the atoms would lie
more or less any way like a series of differently
coloured marbles jumbled together in a bag. In a
compound there would be no single atoms at all, but
groups of atoms, two, three, four, or even hundreds
and thousands firmly held together, each group being
the exact counterpart of each other group. In most
instances, too, the atoms of an element by itself
form little groupings or molecules. Thus, the gas
Oxygen does not exist in the air as single, but as
twin atoms. As will be seen, the chemist, therefore,
writes it as O2, and not 0^
In connection with chemical work figures are used
in two ways. Take such a substance as Sulphuric
Acid. This might be written H2S!O4 (it is written
H2SO4), and means that the unit or molecule of
Sulphuric Acid has, combined together, 2 units or
atoms of Hydrogen, i unit or atom of Sulphur, and
4 units or atoms of Oxygen. In other words, the
SOME CHEMICAL CONCEPTS 123
little figures placed below and immediately after the
chemical symbol state the number of atoms con-
tained in the molecule. Where no figure is given it
is understood that only a single atom is present.
When an expression has a figure on the line before
it, such as 2H2SO4, or 3H2SO4, it means that two or
three molecules of Sulphuric acid are concerned. It
is also possible to bracket subgroups in a compound,
and place a small figure below the line following
the bracket. In such a case there is that number
of the group in the compound. Thus, when the
chemist writes —
6NaCN+Fe(OH)2=Na4Fe(CN)6+2NaOH,
he means, if six molecules of Sodium Cyanide (com-
posed each of one atom of Sodium, one of Carbon,
and one of Nitrogen) are mixed with one molecule
of Ferrous Hydroxide (composed of one atom of
Iron combined with two groups, each consisting of
one atom of Oxygen and one atom of Hydrogen,
reaction occurs, and we get [that is the chemical
meaning of the symbol = ] one molecule of Sodium
Ferrocyanide (consisting of four atoms of Sodium
combined with one atom of Iron, and six groups, con-
sisting each of an atom of Carbon and an atom of
Nitrogen), and two molecules of Caustic Soda (con-
sisting of one atom of Sodium combined with one
atom of Oxygen and one atom of Hydrogen) .
The question naturally suggests itself how these
various compounds are held together. Various
workers have suggested explanations of the problem,
but we are concerned here with what happens rather
124 THE SPIRIT OF THE SOIL
than with why it happens. Experiment has shown
that the different atoms have varying affinities.
We may regard these affinities as hooks sticking out
from the smooth surface of the atom, one hook corre-
sponding to one affinity. Of the commoner elements
in agricultural chemistry, we can state that carbon
r r
has four affinities *— C -* usually written more simply
i -i
— C — ; Hydrogen one, H — ; Oxygen two, — O — ;
I J
Nitrogen sometimes three and sometimes five, — N —
I I
or — N — ; Phosphorus five, — P — ; Sulphur six,
ix
or two, — S — or — S — •; Sodium one, Na — ; and
I \
Potassium one, K — .
The statement can be made generally that there
cannot exist any compound in which any hooks are
left free, or, in chemical terms, all affinities must be
satisfied. Thus, while the substance water exists,
O TT\
Tj_!T~ ~Z_jr, usually written S/O, the substance
OH cannot exist because it would leave an affinity
unsatisfied, thus :
In organic chemistry especially it is of vital
importance to know how the atoms are arranged in
the molecule, because the different groups give very
different results, and two substances may contain
exactly the same atoms with the same number of
SOME CHEMICAL CONCEPTS
125
each, but the resulting properties be quite different.
Thus, Methyl Cyanide—
CH3CN or
I
H
H— C— CEEN
H
is a colourless liquid, possessing a strong but not
disagreeable smell, and is readily soluble in water.
Methyl Isocyanide, however —
CHUNG or
H
H
-N=C
is also a colourless liquid, possessing, as Perkin and
Kipping state without exaggeration, an almost
unbearable odour and poisonous properties.
It is extremely important, and also rather difficult,
to get a clear appreciation of what is meant by
the terms acid, neutral, and base, but a rough defi-
nition is easy enough. An acid is a substance that
reddens blue litmus-paper and that has a sour taste,
a neutral substance has no effect on litmus-paper, a
basic substance turns red litmus-paper blue, and
the more common bases, such as Caustic Potash,
Caustic Soda, etc., have an astringent caustic taste.
It is generally true that an acid body has a Hydrogen
that can easily be replaced by a metal. Thus —
HCl + NaOH
Hydrochloric Acid. Caustic Soda.
Acid. Base.
CH3COOH + NaOH
Acetic Acid. Caustic Soda.
Acid. Base.
= NaCl + H20
Sodium Chloride. Water.
Neutral. Neutral.
= CH3COONa + H2O
Sodium Acetate. Water.
Neutral. Neutral.
126 THE SPIRIT OF THE SOIL
It is also generally true that bases are formed by
metals combined with the group OH — e.g., NaOH,
etc. — and that acids are formed when non-metals
are combined with the group OH — e.g., H2SO4
(Sulphuric Acid).
H~°x°
H— (X ^O
But there are many exceptions, some more ap-
parent than real, such as HC1 (Hydrochloric Acid)
and all the organic acids, such as CH3COOH (Acetic
Acid), where the CH3 group may be regarded as
acting as if it were a non-metal element.
There are not many groups that we have to
consider for the present purpose of this book. The
group of chief importance is the COOH group.
This is the standard grouping that gives acid proper-
ties to organic bodies, and that can be neutralized
when the hydrogen in it is replaced by such a sub-
stance as the Calcium of Lime. The atoms are
combined as follows : — C\ QTJ> and it will be noticed
that the Carbon has one affinity unsatisfied. If a
Methyl group (CH3) is linked on to this we have
Acetic Acid, one of the simplest of all organic bodies :
H
I j&
H— C— C
From this a whole series of organic acids can be
formed by the simple system of inserting any desired
number of the group CH2.
SOME CHEMICAL CONCEPTS 127
Thus—
H H
i I ^0
H— C— G— Cf
I ! NDH I | | XOH
H H
Propionic Acid. Butyric Acid.
and so forth.
This does not end the degree of complexity of the
formation of organic compounds. The formula for
Butyric Acid, for instance, adding up the Carbons,
Hydrogens, and Oxygens, is C4H8O2, but the formula
can also be written —
in which case you get a substance with different
properties, known as Isobutyric acid. When three
more CH2 groups are added, you ggt a body called
Heptylic Acid.
It is possible to write no fewer than seventeen
different structural formulae for Heptylic Acids satis-
fying the necessary conditions, though the formula
is a simple one (C7H14O2), and of these seventeen
hypothetically possible bodies nine are actually
known. The number of hypothetically possible
acids from stearic acid, which is far from being the
most complex of the series known (C18H36O2), can be
imagined.
128 THE SPIRIT OF THE SOIL
The complexities of these substances do not con-
cern us. What has clearly to be borne in mind as
regards them is the simple means by which their
acid properties can be neutralized. This can be done
readily by means of Lime [Ca(OH)2] or Ammonia
(NH4OH, orNH3). Thus—
H H
C-C^ H— C— C/
| X)H XO
H OH H \ nH\
0
+ Ca<; = Ca +
H Npfl H / "H/
I /OH | />
H— C— C/ H— C— C<
i ^° i %0
Acetic Acid. Lime. Calcium Acetate. Water.
or —
H H
I J° S\ I ^° /H H\
H— C— C<; +H^N_0_H=H_(>_C^ /H+ \Q
I XOH j*/ i xo— N:S: H/
H H
rl
Acetic Acid. Ammonia. Ammonium Acetate. Water.
Four fundamental processes occur in the soil in
connection with the decomposition of organic matter.
Oxygen is added to or taken from the molecule, and
the elements of water are added to or taken from
the molecule. If some indication can be given to
the reader as to how these processes can occur, the
general scheme of soil chemistry will easily be
grasped.
In the changes that carbohydrates undergo in
becoming peat the most striking feature is the way
in which the molecule is continually increasing the
SOME CHEMICAL CONCEPTS
129
percentage of Carbon that they contain. One way
in which this is effected is by the loss of water. The
exact changes which occur are not known, but the
following formulae show how such a change might
be effected. The first formula shows how two
molecules of Glucose, 2C6H12O6, might be concen-
trated by loss of water, and form a molecule richer
in Carbon, C12H14O7 ; the second how this, with one
other molecule of Glucose, could change to the third,
showing a still greater amount of Carbon. Thus —
I ;;;.:;;:; .................... : I
H— C— O— H H— C— O— H
130 THE SPIRIT OF THE SOIL
A reaction very commonly met with is the change
of substances through the addition of the elements
of water. This is often effected by boiling the sub-
stance with dilute acid. Thus, the sugar Lactose,
if boiled with dilute Hydrochloric acid, yields the
sugars Glucose and Galactose, a molecule of water
being added in the process according to the
formula :
C12H22On + H20 = C6H1206 + C6H1206
Lactose. Water. Glucose.* Galactose.*
At first sight it seems curious that the effect of
boiling with such a substance as a dilute acid should
be to add the elements of water. It has to be
remembered that when such a body as Hydrochloric
Acid is in solution it splits up. The molecules of the
acid no longer move in the liquid as the unit HC1,
but in a peculiarly active form as H — and Cl — , con-
* These two substances, though they have the same composi-
tion, and in a sense the same structural formulae, have their
atoms differently arranged, so that one would be the looking-
glass picture of the other.
SOME CHEMICAL CONCEPTS 131
tinually combining and breaking apart. The water
also will be going about in the form of H — and — OH.
Then in the solution we may get some such com-
bination as —
H— Cl > H— and Cl—
H2O > H— and — O— H
These might recombine on the lines —
H— jci— " H— I — o— H
The elements of water may split away through
the formation of Hydrochloric acid, as shown by the
dotted ring, and it is a commonly known chemical
fact that compounds in the act of formation or
decomposition will have more active chemical
properties than when they are in a stable state. It
is perhaps for some such reason as this that a common
means for adding the elements of water to a com-
pound is to boil with dilute acids.
The addition of Oxygen to an organic compound
may readily result in an acid being formed. Thus, if
Oxygen were added to any of the bottom C — H
O
groups in the structural formula given above, an
atom of Oxygen would pass in between the Carbon
and the Hydrogen to form the typically acid group
I
C — 0 — H. On the other hand, the addition of
II
O
Oxygen may destroy the acid properties by eliminat-
132 THE SPIRIT OF THE SOIL
ing the Carbon altogether from the molecule, the
group splitting, leaving the — O — H to link on to
another carbon, and forming Q^C (CO2). Thus
Formic acid arid Oxygen will yield C02 and water :
/£> O
H — C\ #
NDH+O=C + H— OH
Formic Acid. ^^
O
By adding Hydrogen to an organic compound its
constitution may be profoundly modified. Thus, the
C — H group referred to above may, under the
II
O
influence of nascent Hydrogen, be changed into an
alcohol, thus :
O-H+aH — > H— C— H
O O— Hj
or, to give an actual equation :
H
U
Ethyl Alcohol.
Another reaction of considerable importance in
connection with organic decomposition is concerned
with Ammonia. The Nitrogen contained in protein
molecules is frequently given off during decompo-
sition in the form of Ammonia, and acids present in
SOME CHEMICAL CONCEPTS 133
the soil are in this way neutralized. Thus one would
get the equation :
H H H
/£) TT\ /& IT H\
Hr* f^js . n\-».T /-\ TT TT /-* fij^ t *•*• i- No
— U — L/v ~r TT /-tN — \J — ri = n — \~> — v>\
I XOH £7 I - _
H H VH
Acetic Acid. Ammonia. Ammonium Acetate. Water.
Base. Neutral,
In conclusion, a few definitions may prove useful :
A CARBOHYDRATE is a compound of Carbon,
Hydrogen, and Oxygen, the two latter elements
being present in the same proportions as they are
present in water. To this class belong the various
celluloses, starches, and sugars.
PROTEINS. — These all contain Carbon, Hydrogen,
Oxygen, and Nitrogen. Phosphorus, Sulphur, and
a few other elements are also often present. It is a
characteristic of the class that the molecule is large,
and contains a number of complex groupings.
FATS. — These are neutral bodies consisting of a
combination of Glycerine and the so-called Fatty
Acids — i.e., acids of the Formic and Acetic Acid
group, which has CnH2nO2 as the common formula
of the group, n being any whole number.
AMIDES. — These enter largely into decomposition
and other changes. They may be regarded as
derivatives of Ammonia (NH3). They are written
/H,
place of simply attached Hydrogen in organic com-
pounds. Their importance in Nature may be
134 THE SPIRIT OF THE SOIL
appreciated by the statements that the formula for
Urea is —
/H
o=c;
\H
and that the amide is an important constituent of the
various alkaloids.
In reading this chapter the caution must be made
against too literal an interpretation of many of the
above statements. No one, for instance, imagines
that an atom is a rounded body with a number of
hooks on it. Recent research, in fact, would suggest
rather that it would be found to be comparable with
a firmament. To derive any value from these more
modern conceptions, however, a chemical training
is necessary, and I have thought it better to describe
the cruder views that very largely obtained in the
recent past, as they are rigidly true in so far as they
gave and still give a true expression to the majority
of the facts with which the working chemist is called
upon to deal.
CHAPTER X
THE TESTING OF HUMOGEN
Difficulties in sciences dealing with living organisms — Complexity
of biological problems — Masking of cause and effect — Nitro-
bacterine — Adoption of the method by America — Essential
to supply bacteria with food — Nature's methods with the
embryo — Comparison with bacterized peat — Richness of
the peat in humus — Response of the laboratory plants —
Experiments at Kew — General results of three years' work —
Plant fertilizers used — Details of improvement noted —
Experiments at Tuckswood Farm : Tomatoes. Beans.
Potatoes — A curious failure — Need for early use of humogen
— Mr. Weathers's experiments: Marguerites. Pyrethrums.
Forget-me-nots. Rhubarb. Cabbages — Digging in of
humogen.
THERE is one inherent difficulty attaching inevitably
to all sciences that have to deal with living organ-
isms— the looseness of the causal relations. Hence
many of the volumes on philosophy. Hence the
fierceness of the fighting between those who insisted
on the doctrine of predestination and those who
championed the doctrine of free will. Hence, too,
the keen controversy that is waged even to-day on
such matters as vitalism in physiology; or, to go
from large issues to small, the campaign of the anti-
vivisectionists. Perhaps the latter question illus-
trates the argument best. Many people who know
that the injection of morphia into a cat violently
135
136 THE SPIRIT OF THE SOIL
excites it, whereas the injection of it into a man and
into most other animals serves to soothe the nerves
and induce sleep, will have it that the experimental
physiologist is following a will-o'-the-wisp when he
attempts to draw general conclusions from the
experiments he performs on the lower animals. I
have frequently been told that experiments con-
ducted on the dog, such as problems of digestion,
are valueless because the dog will swallow and digest
bones, whereas the normal man who ate his meals
on similar lines would suffer terribly from indigestion.
The main underlying fallacy vitiating the anti-
vivisection campaign — when the opposition is not
due merely to sentimentalism — is the common belief
that in cases where living tissue is concerned the
relation between cause and effect is less rigid than
it is in the case of lifeless matter. Scientific biology
is frankly based on the principle that causal rela-
tions do obtain rigidly so far as the material side of
life is concerned, and many biologists — returning to
the problem of predestination and free will — would
hold something closely akin to the doctrine of pre-
destination, and contend that every act is the
inevitable result of an intensely complex set of
causes.
In tracing out causal relations in biology the
worker is confronted with formidable difficulties.
While the physicist or chemist is usually able to
simplify his problem by eliminating all confusing
issues, the biologist has present, as the basis of
nearly all his work, the intensely complex animal or
vegetable cell, or the even more complex living
THE TESTING OF HUMOGEN 137
organism. No one cell is exactly the same as any
other cell, but the cell of any given tissue possesses
certain properties varying within limits round a
common mean. Some chemists believe that a
similar doctrine holds about the elements — for
instance, that one atom of Nitrogen is not the same
as another atom of Nitrogen, but that the atoms
themselves have certain limits within which they,
too, are able to vary.
The complexity of the living cell, and the conse-
quence of this complexity — that cause and effect are
frequently masked — has created considerable diffi-
culties in the researches connected with bacterized
peat. The problem of Nitrogen fixation by means
of bacteria in the case of leguminous plants had been
satisfactorily worked out in the laboratory some
years ago, and in his nitrobacterine Professor
Bottomley had obtained a form of culture which
gave satisfactory results. Tested a little prema-
turely, perhaps, under glass and field conditions, the
nitrobacterine gave several failures because various
factors that were eliminated successfully in the
laboratory upset the necessary conditions when the
bacteria were set to work on the land. Scientifically,
nitrobacterine was a success. As has been stated
previously, the American Board of Agriculture
during the last few years has studied these field diffi-
culties, and is now using a preparation similar to the
nitrobacterine that in this country was too hastily
condemned by many who failed to get results.
One of the essential difficulties in connection with
the old material was to insure that the bacteria,
138 THE SPIRIT OF THE SOIL
when placed in the ground, should have a suitable
medium in which to work. The principle is one
universally recognized in Nature. The young em-
bryo in the seed is sent out by the parent plant with
a stock of food material that makes it independent
for several days of the soil on which it falls. In the
egg the embryo starts its life with a store of material
ready for its needs several thousand times greater
than itself. In the mammal the young embryo
develops firmly fixed to its parent, and even after
birth, by the strength of the maternal instinct,
Nature insures that it shall have for months to come
an abundant supply of the food that it requires.
Nitrobacterine was a compromise between the
earlier system of the Germans and Americans and
that used with bacterized peat. In the cotton-wool
preparations the bacteria were sent out with no
food-supply to nourish them, and many of them died
before ever they reached the land they were intended
to fertilize. Nitrobacterine (earth impregnated with
bacteria) through the humus it contained, insured
that the bacteria should have some food to support
their life during the period of waiting ; but the system
of utilizing them carried with it the objection that
on being applied to the soil they had at once to
secure their food from the ground in which they
found themselves. The failures with the prepara-
tion showed that an important factor had been
neglected, and, unconsciously to some extent, the
laboratory workers were thrown back to imitate the
system followed by Nature in the egg and seed.
Peat was a substance rich in the raw material of
THE TESTING OF HUMOGEN 139
humus. It was known that in time, under the
influence of bacteria, the peat changed, forming
soluble humus, and experiments were made to see
whether the process could not be hastened by arti-
ficial means so that the bacteria might be distributed
in the soil with an abundant supply of food to
enable them to start their growth.
The success of treating the peat with bacteria was
startling in the unexpectedness of its results. On
testing peat that had been exposed to bacterial
action it was found to be amazingly rich in soluble
humus, to yield, in fact, fifty to eighty times as much
as could be obtained from a corresponding weight of
the best rotted stable manure. Laboratory experi-
ments followed. As was to be expected, the Nitrogen-
fixing bacteria, Bacillus radicicola and Azotobacter
chroococcum flourished and multiplied when placed
in such a medium. Plants, too, responded readily
to the peat. When grown in sterilized sand watered
with the peat extract they grew luxuriantly, develop-
ing healthy roots, giving luxuriant foliage, and
coming more rapidly to maturity, thus proving that
Humogen contained everything necessary for plant
growth.
The exact position of the work at this stage was
defined by Professor Bottomley in a paper he read
before the British Association at Dundee in 1912.
His official summary of the paper giving the essential
facts was as follows :
" Peat-moss litter is said to be ' entirely unsuited
for the growth of plants.' It is acid in reaction, and
contains no soluble humates.
140 THE SPIRIT OF THE SOIL
" It has been found, however, that when peat is
treated with certain micro-organisms a large quantity
of soluble humate is obtained, and the peat is ren-
dered alkaline. An aqueous extract of this treated
peat (i part peat to 200 parts water) will supply all
the plant-food necessary for successful water-culture
experiments. As no trace of nitrate was found in
the culture solutions during the whole course of the
experiments, it is evident that the nitrogen need of
the plants was supplied by some form of organic
nitrogen present in the solution.
" Water-cultures with tomato seedlings, ger-
minated in sterilized sand, showed that the plants
failed to grow in raw peat extract, but in treated
peat extract the plants grew well, flowered, and
produced fruit. Experiments with buckwheat,
radish, and barley gave similar results."
In view of the disappointment with nitrobacterine
it seemed unwise to attempt to generalize from the
laboratory results, and three years ago the authori-
ties at Kew Gardens were asked if they would be
willing to conduct experiments with the new
material.
The authorities at Kew consented. It is un-
necessary to state that Kew Gardens are ideal for
such a purpose, having the facilities necessary for
conducting large scale experiments, and the per-
sonnel competent to experiment on rigidly scientific
lines. There was an additional advantage, however,
about Kew. Experiments had already been tried
there with nitrobacterine, and had given negative
results. Naturally, therefore, the authorities were
inclined to be sceptical, and the stringency of the
tests to be made was insured.
THE TESTING OF HUMOGEN 141
In the first year the effect of using the peat in
various quantities on plants grown in ordinary soil
was tested, and plants were grown in ordinary soil
and other media as a control. Commenting early in
1914 on the results obtained, Mr. J. Coutts, of Kew
Gardens, said (Journal of the Royal Society of Arts,
March 15, 1914) that " the plants, beyond ordinary
details, had no special attention during growth other
than that devoted to starting them ; after a fortnight
or so they were left to themselves. The results in
some cases were extraordinary, and not comparable
with those obtained from ordinary nitrogenous
manure. Experiments had been made to determine
whether peat afforded plants a greater power of
resisting the eel-worm, and in this connection the
carnations showed the most striking results. In the
case of the peat -treated plants there was little trace
of eel-worm after two months' growth, whereas the
nitrated plants were badly affected within a fort-
night. Another experiment was made with chrys-
anthemum plants in the open, planted at the same
time and under the same conditions. One section
of this planting was treated with 2 ounces of peat
to the square yard, a second with 4 ounces, while
a third section was treated with dried sewage
sludge, and a fourth with nitrates. The differences
in results were marked. The section treated with
the smaller quantity of peat seemed as good as that
which had received a larger allowance. Again the
sludge section was considerably superior to that
which was nitrated, although much inferior to the
peat-treated sections, the action being slower. It
142
THE SPIRIT OF THE SOIL
was evident that there was something in the nature
of manurial effects in the peat, the root development
of the plants being very marked."
The experiments conducted during the first year
at Kew — other experiments, as is shown in Ap-
pendix B, were in progress elsewhere — were very
striking, and when in the second year they were con-
siderably extended, the beneficial results obtained
from the bacterized peat were fully confirmed.
During the present year I visited the gardens to
see the progress of the experiments now in progress.
The final results of this year's work have, of course,
not yet been obtained, but the influence of the peat
on the plants at present growing there is extremely
striking. For the various classes of work there nine
different soil mixtures have been used for compara-
tive purposes. They are as follows:
Soil
Leaf mould
Sand
As No. i, but sterilized
3. Sterilized soil 54-6
Leaf mould 18-6
Sand . . 8 to 9
Lime rubble 8 to 9
Sewage sludge 8 to 9
Basic slag 0-5
Bone meal 0*5
Soot ... 0-5
Sulphate of potash 0*3
4. Sterilized soil ^ 80
Humogen "* 10
Sand . . 10
5. As No. 2, but newly sterilized soil.
6. No. 2, plus 0-04 per cent. Gafsa Phosphate.
7. No. 6, plus 12-5 per cent. Humogen.
8. No. 2, plus 0-43 per cent. Gafsa Phosphate.
9. No. 8, plus I2'5 per cent. Humogen.
soil.
Per Cent.
66
22
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THE TESTING OF HUMOGEN 143
A great variety of plants have been used for
experiments, Cotton, Tobacco, and Fuchsia being
among the numbers. In most instances the plants
grown in mixture No. 4 are so markedly superior to
those for which any other mixtures have been used
that the difference is apparent to the casual glance in
the increased size and improved healthiness of the
treated plants. Occasionally the complete fertilizer
mixture, a mixture containing every possible form of
food that a plant can require, has given as good
results, but this is exceptional. What is especially
noticeable at Kew Gardens is the increased root
development of the plants treated with the peat.
On taking the plants from the pots an abundance of
root is characteristic, there being a striking differ-
entiation in this respect between the plants grown
with peat and those grown with other soil mixtures.
Another feature, commonly noticed with variegated
plants, is the intensification of the variegation which
is comparable with that noticed in the colours of
the flowers. This has proved one of the unexpected
results of treatment with peat. Both foliage and
blooms are often richer in tone, the improvement in
foliage emphasizing and reinforcing that obtained
on the blooms. An increased sturdiness of the
stems may be regarded as being naturally connected
with the general symmetrical growth of the treated
plants, but in several instances it is strikingly
marked, notably at Kew in the case of the cotton
and tobacco plants. Generally, also, the plants are
larger and tend to mature earlier.
While writing the present volume I took advantage
144 THE SPIRIT OF THE SOIL
of an invitation from Mr. Robert Holmes, of Tucks-
wood Farm, Norwich, to visit some experiments he
has been conducting with the bacterized peat. His
gardens cover a large area of ground, and are devoted
chiefly to the growing of sweet peas and tomatoes,
but this year, particularly as a consequence of the
war, potatoes have also been grown on a considerable
scale, and a fair number of small parcels of ground
have been laid down for the experimental raising of
beet, mangel-wurzels, sugar-beet, etc.
Unfortunately, a single factor, the persistent dry
weather of the spring, has so far made several of the
results obtained of little value, as will be realized
when it is stated generally that in several of the
fields it was not possible to detect the slightest differ-
ence between crops that had been grown in ordinary
soil and those grown beside them, which had received
extra treatment with farmyard manure.
In the glass houses devoted to tomato-growing,
where the plants have been treated under the best
known conditions, the effect of humogen has been
so striking that even the amateur can tell at a glance
which of the pots have received dosage with humogen
and which have been grown under strictly com-
parable conditions, except for the non-addition of
the humogen. Four groups of experiments in all
were tried. Five pots received ordinary soil alone,
five received soil and manure, five received soil and
humogen, and five soil, manure, and humogen. In
all cases the plants were strong and healthy, and
had fruited well, but those treated with humogen
were taller plants than the others ; their leaves, which
I
FIG. 9
The tomato plant above is representative of a group grown
from the seedling stage with the aid of humogen. The
darker fruits at the base of the plant had ripened at a
time when only one or two fruits on the untreated were
beginning to redden. The treated plants averaged about
sixteen pounds of fruit per plant, that ripened from three
weeks to a month earlier. (Note yard measure.)
(Grown by Mr. Holmes, Tuckswood Farm, Norwich.)
THE TESTING OF HUMOGEN 145
were rather smaller, showed the peculiar rich bluish-
green tint that is associated with vigorous growth,
and in the case of the humogen-treated plants there
were clusters of red fruits, while on the others the
fruits were only beginning to change from green to
red. The tomatoes on the humogen-treated plants
were indeed over-ripe, as they had been left on the
plants so that full opportunity might be given for a
comparison between the humogen-treated plants and
the others. Also, as the accompanying illustration
demonstrates, the humogen-treated plants showed a
greater quantity of fruit than the plants not treated.
In one of the houses near to the tomato houses a
somewhat similar experiment had been conducted
with the Guernsey Runner Bean. In this case
humogen-treated beans have made striking progress
both in growth and in quantity of fruit. They
stood several inches higher, and had large, well-
formed leaves, showing a deeper green than that on
the plants near by. From both groups of plants pods
had been pulled, and neither group had as yet
finished fruiting.* Already there had been a marked
increase in yield ; the humogen-treated plants showed
* While this book was going through the press a report was
received from Mr. Holmes giving the weights of beans pulled
from two typical plants. They are —
Plant grown Plant grown
with Humogen. without Humogen.
Lbs. Ozs. Lbs. Ozs.
June 30 o 13^ o 15^
July ii .. . . . . o 12! o y|
July 23 i 13! o i|
August 4 . . . . ..14 i o
Total .. . . 4 ii J 2 8£
146 THE SPIRIT OF THE SOIL
signs of improving their present lead; already
2 ounces more of pods had been pulled from the
treated than from the untreated plants, and their
increased vigour was manifest.
A chance experiment conducted casually outside
one of the houses gave an astonishing result. Mr.
Holmes told me that he remembered reading some
years ago of some French experiments in which
ordinary moss had been used as a medium for
growing plants, while the plant food had been sup-
plied in the form of liquid manure. It had occurred
to him that it would be interesting to try the effect
of growing potatoes in moss, moistened from time
to time with the water extract of humogen. He
planted four potatoes in sterilized moss in a shallow
box, I5-J- inches long, 6 inches wide, and 4 inches
deep. No special care was given to the potatoes.
As a start the moss was soaked in humogen extract ;
they were watered from time to time, and occasion-
ally were sprinkled with the water extract of
humogen. The box, as we saw it, showed a luxuriant
growth of leaves standing about a foot from the
level of the box, but when the plants were pulled
the roots were found to be crowded with tubers,
several being of considerable size, and the majority
being still immature. Their total weight was
2 pounds io£ ounces, all contained in an area of a
fifth of a cubic foot.
Most of the field experiments here this year at the
time of writing are inconclusive, for the crops have
not yet been dug up. In several instances, how-
ever, it was possible to appreciate at a glance that
the potatoes, sugar-beet, etc., which had been
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THE TESTING OF HUMOGEN 147
treated with the peat, were markedly superior to
those which had not received treatment.
Mr. Holmes's experiments were interesting for
another reason. There was a single field of potatoes
— the whole was a markedly poor crop — one large
corner of which had been treated with humogen, but
had otherwise received exactly the same manure as
the rest of the field, and to the eye the crop on this
area was markedly inferior to that on the rest of the
field. It is the first instance that I have met with
personally in which apparently the treatment with
humogen has retarded growth. The soil is now
being analyzed and the other conditions studied to
find out why this unusual result should have been
obtained.* That the treated peat of itself can do
harm is impossible, as plants have been planted in
pure humogen and done well. It is possible that
the plot may improve before the potatoes are dug
up, but the fact remains and has to be faced that
there is a prima facie case here that there may be
certain rare soil conditions other than mere acidity
which will need correction before humogen can be
successfully applied. It has to be remembered that
the present season has been abnormal, and that the
lesson it teaches is that it is advisable to dig the
humogen into the soil early in the year at a time
when the chance of drought has not to be feared.
As will be seen from Appendix B, there are many
other places where experiments have been made with
* While the book was going through the press I heard from
Mr. Holmes that with the advent of an ample rainfall the plot
improved, and now (September 3) at least equals any other
portion.
148 THE SPIRIT OF THE SOIL
the treated peat. There is only one other garden,
however, that I have been able to find time to visit
while writing this book, a market garden kept by the
well-known horticultural writer, Mr. John Weathers,
at Isle worth. The conditions under which he has
had to conduct his experiments have not been very
favourable to the peat, as in most cases it could not
be delivered to him until the plants were already
in the ground. In such circumstances, combined
with the drought, he obtained only negative results
by top-dressing in the case of bulbous plants. With
Marguerite daisies, however, a striking and valuable
result was obtained. His crop generally was top-
dressed with the peat, but there was one portion of
ground in which he was able to dig in the humogen in
the quantity of 2 J ounces to the square yard. Mar-
guerites were planted in this, and though they were
planted later than the others, they flowered a week
earlier.
With Pyrethrum the peat gave excellent results.
By May 25 the treated plants were being cut, while
by June 4 cutting had not commenced on the plants
which had not been treated. Lily of the Valley
responded well to treatment, while Forget-me-nots
bloomed in greater abundance when treated with
the peat and compared with untreated beds. On
Rhubarb the rows receiving humogen were con-
siderably in advance of a row that was left un-
treated. Apart from the experiments on wheat,
described in the chapter on General Results, the
most striking of Mr. Weathers's results were those
he obtained with some cabbages. The peat was
a plied, i ounce to the square yard, to a plot of
THE TESTING OF HUMOGEN 149
ground in which the throw-outs from another bed
were planted. At the start the cabbages were
miserably weakly plants. Under humogen treat-
ment, however, they picked up well, and though they
matured rather later, there was in the end nothing to
choose between the originally weakly plants after
the treatment with humogen, and those cultivated
along ordinary lines.
In discussing the results generally Mr. Weathers
emphasized to me the importance of digging in the
humogen instead of merely using it as a top-dressing,
but there was no doubt left in his mind as to the
marked improvement to be obtained through a use
of the peat, both in the increase of the crop and in
the early maturing of it.
In the short space available in this chapter I have
tried to indicate the basis on which the case for
humogen stands. Both from the laboratory stand-
point and from the standpoint of the grower under
glass the value of humogen as a routine method of
treatment seems to me definitely established. The
experiments made to extend the use of humogen to
field-work on a large scale are extremely encouraging,
and at present there seems no reason to doubt that,
when suitably applied, results comparable with
those got in the laboratory and greenhouse will be
obtained in the field. If this result, however, is to
be obtained rapidly, the co-operation of the farmers
and the farming stations throughout the country is
essential, as it is only by extensive experiments care-
fully carried out that the conditions necessary for
the best results will be satisfactorily determined.
CHAPTER XI
THE PREPARATION OF HUMOGEN
mportance of cost and availability of humogen — The works at
Greenford Green — Railway facilities — The raw material —
Incubating with humating organisms — Sterilizing the peat —
Inoculation with Nitrogen-fixing organisms — New system
of sterilization — Project for rapid drying — Possibilities of
extension — Price as compared with manure.
IN the course of the discussion on a paper read by
Professor Bottomley before the Royal Society of
Arts on "The Bacterial Treatment of Peat/' Dr.
J. A. Voelcker said that from a practical point of
view the cost of the material was paramount, and he
asked the question whether there was any likelihood
of the material being put on the market in an acces-
sible form. In the eighteen months which have
elapsed since the date of the reading of that paper,
the situation as regards the bacterized peat has
changed very materially. Two seasons of experi-
ments have confirmed the results that were then
announced, and the peat is already being manu-
factured on an experimental scale. While the whole
story of soil inoculation and of the auximones is
keenly interesting for its own sake, in so far as it
throws fresh light on the nature and mechanism
of plant growth, from the national standpoint at
any rate, and from that of the practical grower, the
150
THE PREPARATION OF HUMOGEN 151
essential considerations are, firstly, whether the use
of humogen will increase the yield of the crop to the
extent that is believed will be the case by those
responsible for its production, and, secondly, how
far the grower can rely on getting the peat in the
quantity he requires at a reasonable cost. The
preceding chapters in this book constitute the
answer to the first of these questions, and it is for
those who are not satisfied with the evidence brought
forward to conduct further experiments for them-
selves on their own land.
To furnish an answer to the second question, I
have visited the factory at Greenford Green, near
Harrow, partly to see how the process of preparing
the peat is conducted in bulk and partly to deter-
mine how far it would be possible to increase the
output to meet a large demand. The factory where
the raw peat is changed into humogen is situated on
six acres of ground, and occupies the old buildings
used by Sir William Perkins for his dye-works. So
far only a fraction of the ground is employed, and
the old chimney-stacks are still standing as a relic
of the great industry which, partly as a result of the
attitude of the Government towards science, and
partly owing to the national apathy, has been
developed into a world-wide industry by Germany.
Both for rail and water transport the factory is
admirably situated. It is well served by the Grand
Junction Canal and both the Great Central and the
Great Western Railways.
The peat is brought to the works in the large bales
most familiar to the general public as the way in
152 THE SPIRIT OF THE SOIL
which the peat is distributed to stables as peat -moss
litter, and on arrival is broken up and stored at one
end of a large shed. Water-heated pipes pass
through half a dozen bays, and into these the peat is
thrown when it has been moistened and thoroughly
well impregnated with the aerobic bacteria which
change the insoluble Humic acid of the peat into
the soluble humates required, both as a bacterial
and as a plant food. The peat lies in these bays for
about ten days, remaining all the time at the tem-
perature which is best suited for the development of
the bacteria. During the process it tends to settle
down. It darkens in colour, but otherwise there is
to the unaided senses no sign of any change taking
place. Notably the whole process occurs without
the development of any smell. Close to the bays
the large boiler is situated. It is designed to carry
an 8o-pound pressure of steam. The steam from it
passes through pipes, and ends in two large water-
jacket cauldrons of the type used in melting tallow.
It is set free in these cauldrons through holes pierced
in the pipes to insure that the steam shall thoroughly
saturate the peat. Once this has been fed into the
cauldrons steam is applied to them for a period of
about an hour, a period that has proved sufficient
to insure the death of all the humating organisms.
From the cauldrons the peat, now sterile and rich
in plant foods, is removed to another shed, where it
is impregnated with Nitrogen-fixing organisms,
Bacillus radicicola and Azotobacter chroococcum.
These require only a short time to develop in the
fertile sterilized peat, and this is then spread on the
THE PREPARATION OF HUMOGEN 153
floor in heaps and air-dried. As soon as it is dried
it is packed in bags and is ready for use.
Such is the process as it has been worked for some
time now at Greenford Green. The description, how-
ever, only gives a slight idea of what has been done.
While I was at the works, an experiment, suggested
by Mr. Holmes of Tuckswood Farm, Norwich, as a
result of the work he has done in sterilizing soil, was
in progress. It appears to be practicable to avoid
the use of the cauldrons for sterilizing the peat and
to substitute for them a rough frame which lies on
the ground, and carries his patent " norvic " cover.
Steam on being applied to this Hght frame, so far as
the experiments have gone, is able effectively to
sterilize the peat, and if the process on further ex-
periment proves satisfactory, there will be a con-
siderable saving of labour and space, and an increase
of convenience in the handling of the peat.
Already in view of the increased demand a machine
is in course of installation which at first sight
resembles a tubular boiler. There are steam com-
partments at either end, and a large number of pipes
running between them . The proposal is to mount this
apparatus and to keep it revolving while the prepared
and inoculated peat is being automatically shovelled
against the warm pipes, a method that would greatly
shorten the time necessary for the whole operation,
and facilitate the very difficult process of drying.
I have been at pains to describe the system
employed to prepare the peat at some length, as it is
clear from the description that the present rate of
manufacture could be very greatly extended. For
154 THE SPIRIT OF THE SOIL
the time being only a portion of one of the sheds is
being used, but there would be no difficulty in
meeting an increased demand at once by duplicating
or triplicating the present plant. Hitherto it has
not seemed desirable to manufacture on a large scale,
as the work at the factory has as yet been only
experimental. Various samples of peat are con-
tinually being tested, as experience shows that
different samples of peat show large differences in
the quantity of soluble humus that they yield, and
it has been thought better to carry through the
necessary preliminary work on a small scale before
fitting up a plant which might prove better or worse
suited to the particular quality of peat ultimately
adopted as the standard.
As regards cost it is difficult to state anything
definitely. While the process was in the experi-
mental stage the price of the peat was provisionally
fixed at 155. for 3 bushels. This price was fixed
arbitrarily to meet the convenience of those who
wished to conduct experiments, but there is reason
to believe that when the substance is dealt with
commercially a price will be practicable at con-
siderably less than £10 per ton. For purposes of
comparison with ordinary fertilizers it may be
assumed, for the moment therefore, that the cost of
it is about £10 per ton. In view of the fact that the
available plant food in peat, as compared with that
in rotted stable manure, is as between fifty and
eighty to one, the superiority of the peat from the
standpoint of its food value alone, when considered
in relation to its cost, is strikingly apparent.
CHAPTER XII
PRESS AND OTHER CRITICISM
Early hostile criticism — Lines of attack — Sound basis of criticism
— Need for experiment — Growth of opinion in favour of
inoculation — Support from the Board of Agriculture —
Royal Society of Arts meeting — Two opinions of experts —
Press criticisms.
THERE has been no lack of criticism of the work done
by Professor Bottomley on Nitrogen-fixing organ-
isms. Of this it is possible for me to speak person-
ally with some authority, as it has been my business
as a journalist ever since the earliest publications
were made on the subject, not only to keep in touch
with the various stages of the work in King's College
Laboratory, but to make inquiries of agricultural
experts and others as to their opinion of the work.
I have also from time to time attended not only
popular meetings where the method has been ex-
plained, but also scientific meetings where the views
put forward have been discussed by critical
audiences.
In the earlier years I heard a great deal of hostile
criticism; it was criticism of the sort that is in-
valuable to the journalist, given to him in confidence
for the guidance of his paper. I was advised repeat-
edly to be very cautious in what I wrote; I was
55
v
156 THE SPIRIT OF THE SOIL
warned of the extreme difficulty of field experiments.
It was pointed out to me that, even when every care
was taken to give the whole of a field identical treat-
ment, such a field, if divided into plots, would yield
returns from certain plots that would vary by as
much as 50 or i oo per cent, from the mean, and that
long-continued experiment, therefore, was necessary
before the results claimed for soil inoculation could
be accepted. Professor Bottomley, I was told very
truly, was an enthusiast with more laboratory than
field experience, and might have been misled by
results apparently due to the bacteria, but due in
reality to other causes of which he had no know-
ledge. Facts and figures were quoted to me showing
how frequently in the past generalizations have been
made by men of science in connection with agri-
culture on insufficient experiments, and that the
result has been disappointment and the discrediting
of science among practical farmers.
Experience has shown that there was real wisdom
underlying these criticisms. From the standpoint
of the practical man nitrobacterine was a failure,
because it was not realized that certain conditions
were essential for its successful application. Scien-
tifically, however, it was a success, as is proved by the
fact that after seven years of experiment the Ameri-
can Board of Agriculture is distributing a similar pre-
paration to farmers and recommending its use.
As against the criticisms I heard, there were the
results that were obtained. The laboratory experi-
ments proved conclusively that under controlled
conditions nitrobacterine gave results of an order
PRESS AND OTHER CRITICISM 157
that could be obtained by no other means. The
reports received from growers showed that there
were instances, too many to be accounted for by
chance, in which results of the same order as those
gained in the laboratory were obtained, but under
glass and in the field. I considered then, as I con-
sider still, that it was desirable in the interests of
agriculture that extensive field experiments should
have been carried out by farmers, as the evidence
indicated that in nitrobacterine there was a new
means available for increasing the returns that could
be won from the soil, and that it was only by experi-
ments conducted on a large scale that it would be
possible to determine the best conditions for its use.
Seven years have gone by since nitrobacterine was
tested on at all a considerable scale, and during that
period there has been a marked change in scientific
opinion. There is still scepticism in many quarters,
but whereas in the early days Professor Bottomley
stood almost alone in this country in advocating the
practical use of inoculation, he has to-day a con-
siderable body of expert opinion that is with him.
Experience with nitrobacterine has resulted in what
might have been expected. Certain of the con-
ditions necessary for successful inoculation are now
understood. In humogen a means of introducing
the bacteria has been discovered, which very
materially reduces the risk of negative results. The
Board of Agriculture and Fisheries has recognized
the value of the work by making a grant in aid of
the researches, and the time is ripe to-day for the
conducting of experiments on a large scale. To
158 THE SPIRIT OF THE SOIL
show that this is a general opinion I have thought it
desirable to quote here a couple of the views to
which experts have given expression during the
last two years, and also to quote the views of several
leading newspapers.
At a large meeting held early in 1914 at the Royal
Society of Arts, Professor Keeble, F.R.S., who was
in the chair, opened the discussion, and said "he
could put it that Professor Bottomley was able to
take material of small commercial value, used
mainly for the making of fuel and oil, and extract
from it not only the humates in a form in which
they could be used for plants, but also to use these
humates as a seed bed in which the Azotobacter, a
Nitrogen-fixing organism, could thrive. If more
extended trials than those so far undertaken could
establish that Professor Bottomley could do these
two things, he would have earned the encomium of
Swift for those who made two blades of grass grow
where one grew before/'
Dr. O. Rosenheim said "he believed that bacterized
peat was a substance having remarkable properties
as a stimulant to growth. He had himself carried
out a few experiments for the purpose of investi-
gating the minimum quantity of the peat which
would produce the results which Professor Bot-
tomley had shown; the quantity proved to be very
small indeed. He had found that a solution pre-
pared from the peat, containing only about 30 milli-
grammes of solid substances, produced striking
results on plant growth. His results showed that the
effect of peat was out of all proportion to what
I!
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'is*
PRESS AND OTHER CRITICISM 159
would be expected from an equal weight of a mere
manurial substance. The amount of Nitrogen in it
could not supply the needs of the plant, and that
remark was equally applicable to the amount of
phosphates, etc., present. There appeared to be
some fundamentally new substance at work, a sub-
stance which was at the bottom of plant growth. It
had struck him that the active principle in prepared
peat had some analogy to a newly discovered factor
of animal nutrition, which was still in its infancy.
He believed that, directly or indirectly, the plant
obtained what it required from the humus, and that
in the peat as prepared by Professor Bottomley the
essential substance for growth was present. Of
course it was advisable to be very cautious in bring-
ing forward such a view, but the experiments so far
carried out seemed to support it, and he believed
that Professor Bottomley's bacterized peat con-
tained in relatively large quantities a substance of
fundamental importance."
Country Life, October 25, 1913.
" Professor Bottomley's results, both in the field
and the laboratory, have been extremely good. His
prepared peat contains over fifty times as much
available plant food as farmyard manure. . . .
There is no doubt that the prepared peat is of great
value as a manure ; but whether its fertilizing action
is due to the presence of Nitrogen-fixing bacteria,
or merely to the larger quantity of soluble humates
produced during the preparation of the medium,
cannot yet be said to have been definitely proved,
while the peat has also a beneficial mechanical
action on the soil. If only the product can be
160 THE SPIRIT OF THE SOIL
manufactured at a reasonable cost, its value will be
immense to those who go in for intensive cultivation,
to market gardeners, to horticulturists, to farmers,
and for use on golf greens."
Eastern Daily Press, May 8, 1915 (Mr. F. I. Cooke).
" In the course of our Bournemouth experiments
it was clear to me, a fairly old campaigner in manurial
experiments, scientifically conducted, that there
must be some other key to our remarkable results,
and to the far more extensive ones at Kew Gardens.
All who are scientifically acquainted with the sub-
ject, and have studied it in practice, know very well
that amongst the foods of plants the only one
hitherto shown to be an excessive stimulant is
Nitrogen, in one or other of the forms in which it is
usually applied. The various manures of mineral
origin, such as phosphates, potash, etc., are all mild
in their action, tending to sound and steady growth
to well-ripened seed, or fruit or wood, whilst too
much Nitrogen upsets the balance, and merely tends
to sappy growth and more abundant foliage than
can be properly matured. But the striking feature
of our experiments with the peat was that the entire
development of some of the plants, both above and
below ground, was almost doubled in the short
period of six weeks, and yet was perfectly sound and
well balanced. I felt sure, therefore, that some
factor previously unknown, other than the excess of
Nitrogen, provided by the peat, was thus indicated.
I do not mean that it had not been at work before,
but that its identity as a separate nutrient had not
been recognized or even suspected before. Later
developments of the peat investigations have appar-
ently shown this conclusion to have been fairly well
justified. The Professor was perhaps building better
than he knew, and was on the track of an accessory
PRESS AND OTHER CRITICISM 161
plant food new to science, and one which in addition
to its extraordinary scientific interest, may prove of
very great practical importance."
The Field, May 21, 1914.
;' There is good reason to think that Professor
Bottomley has solved the problem of enhancing the
fertility of the soil by the application of bacterial
cultures. As has already been explained in the
garden department of the Field, peat has been
utilized as the medium for impregnating the land
with the cultivated bacteria, and the results at Kew,
the Chelsea Physic Garden, and other centres, exceed
even the expectations of the inventor. The farmer
is not entirely dependent upon the experiments with
garden plants for his appreciation of the discovery.
The bacterized peat, as the preparation has been
aptly termed, has been used for potatoes, turnips,
beet, onions, and carrots, and the effect in all cases
has been pronounced, the treated peat easily sur-
passing farmyard manure and a mixture of arti-
ficials in influencing production. The average in-
crease in potatoes over artificials was 75 per cent.,
and over dung 41 per cent. ; turnips, 47 per cent, and
26 per cent.; beet, 54 per cent, and 53 per cent.;
onions, no per cent, and 46 per cent.; and carrots,
20 per cent, and 28 per cent. Most of these crops
are of chief interest to the market gardener, but it
may be assumed that the material will be similarly
effective upon field crops. The discovery promises
to be of the greatest importance to intensive culti-
vators, whose prosperity has been menaced by the
reduction in the supplies of town manure. Mineral
and chemical fertilizers are valuable substitutes, but
a vegetable preparation such as treated peat would
be attended with less risk of ultimate injury to the
land. The preparation will not be put upon the
162 THE SPIRIT OF THE SOIL
market until its qualities have been thoroughly
tested, and, of course, until an estimate of its cost
is available it will be impossible to appraise its
value as an agricultural accessory. The prospect at
present, however, is exceedingly bright, and farmers
will do well to watch its progress and developments
during the coming season.''
The Field, August 7, 1915.
" Humogen is the name given to what has hitherto
been known as bacterized peat, a preparation which
Professor Bottomley has made famous by proving
that it stimulates plant growth, not only with
respect to fatness of leaves and shoots, but also with
respect to the free development of flowers, fruit, and
roots. Exactly what it is that causes ordinary farm
and garden soil to become so exceedingly fertile
when humogen has been added to it may be known
to Professor Bottomley, but it is not clear to the
practical cultivator, who understands well enough
the action of fertilizing manures, natural and arti-
ficial, but is puzzled by the stimulating influence of
ordinary peat moss to which nitrogen-fixing bacteria
have been added. This peat before treatment is of
very little value to the cultivator. It may contain
plant food as well as the humic acid, the presence of
which is said to render the food unavailable; but
assuming that the whole of this food is freed by the
treatment to which it is subjected by Professor
Bottomley, that alone would not account for the
growth made by the plants fed with it.
" It appears likely that we are on the track of
important revelations respecting plant food, for we
are assured by men like Dr. Russell that the text-
books are quite wrong on the subject. What culti-
vated plants really require, and the easiest and
best way to supply it, are questions of great import-
PRESS AND OTHER CRITICISM 163
ance, the answers to which, according to the most
recent investigations, have hitherto been misleading.
Meanwhile we have Professor Bottomley's highly in-
teresting experiments with bacteria and peat or peat-
moss, showing that even soils which are considered
to be worthless for agriculture or horticulture con-
tain a rich supply of plant food which only requires
to be released by a process of inoculation to produce
abundantly. Evidence of this is gradually accumu-
lating as the result of experiments with farm and
garden crops by trustworthy persons. One of these
is Mr. R. Holmes, Tuckswood Farm, Norwich, to
whom we are indebted for the two photographs here
reproduced, showing the influence of humogen on
the potato and the tomato.
" The tomato plant is a sample of a number that
were grown in ordinary garden soil, to which humogen
had been added in the proportion of one in eight. As
can be seen in the photograph (p. 146), the plant
grew vigorously, but did not develop large leaves,
as tomatoes grown with ordinary stimulating foods
generally do. On the other hand, it bore an excep-
tionally good crop of well-formed fruit, which ripened
perfectly, and when gathered weighed 16 pounds.
' The potato plants were grown in a wood box,
21 inches by 6 inches by 4 inches, which was filled
with ordinary wood-moss that had been steamed
to sterilize it, and then saturated with a solution of
humogen. Four potato sets were planted in this
on May 18, and the box was placed on a border in
the open, where it was watered weekly with the
same solution. On July 22 — that is, two months
after planting — the contents of the box were exposed
and photographed. The new potatoes were clean
and well formed, and they weighed 3 pounds. No
doubt the moss contained a certain quantity of
plant food, and the sterilizing would improve it, but
no experienced cultivator would expect to get a
164 THE SPIRIT OF THE SOIL
good crop of potatoes from it, and we must therefore
conclude that the humogen was both food and
stimulant.
" These results are similar to those obtained pre-
viously with a large number of different kinds of
plants grown in pots, for which humogen was used.
So far as we understand this peat preparation,
nothing is added that would be called a manure,
either chemical or organic, and the question we
would like to ask Professor Bottomley is, would any
kind of soil other than peat or peat -moss be similarly
affected by his treatment ? If by adding certain
bodies to peat he can change its plant food properties
so enormously, would it b$ possible to add these
bodies direct to, say, a ten-acre field or a fruit
orchard, applying it as guano, for example, is
applied ? Or is the peat an essential part of the
fertilizer ?"
Gardeners' Chronicle, October 25, 1913.
" It will be patent to everyone that if it should
prove possible to make peat plant food cheaply, and
if further trials confirm the results of those which
have been made at Kew and elsewhere, Professor
Bottomley's discovery will be of great service to
horticulture and agriculture."
Gardeners* Chronicle, March 21, 1914.
" Briefly these new facts are that extremely small
quantities of a watery extract of bacterized peat are
potent stimulators of plant growth. For example,
it is stated, on the authority of Dr. Rosenheim, who
carried out the experiments, that plants treated
twice with the water extract of 0*18 gramme
( » T^ ounce) respond very readily to the treatment,
and grow away from untreated ' control ' plants.
PRESS AND OTHER CRITICISM 165
" If the result of other more extended and similar
experiments is to confirm the correctness of this
observation, we shall be face to face with a discovery
of prime importance, for it is wellnigh certain that
this growth-accelerating effect of the extract cannot
be brought about by the nitrogenous or other
ordinary substances contained in that extract.
The actual amounts of nitrogen — and of phosphorus
— contained in T|^- ounce of the bacterized peat
must be extremely small — far too small, as it would
seem, to produce a marked increase in the rate of
growth of plants potted in ordinary garden soil."
Gardeners' Magazine, October 3, 1914.
" Professor Bottomley, of King's College, London,
has found that when peat has been subjected to the
action of bacteria it becomes transformed, and acts
as a manure of considerable value."
Pall Mall Gazette, June 6, 1914.
" The whole conception of the growth of plants
may have to be altered as the result of some im-
portant experiments that have been made at
King's College, London, and since submitted to
successful tests at Kew and Chelsea. Just as
modern research has discovered that growing animals
cannot get the full value out of pure food, and will
not continue to grow unless there is some trace of
what is termed " accessory food body" used with
it, so it is thought there is in bacterized peat a sub-
stance similar to the accessory food bodies necessary
for growing animals. And the theory is that plants,
just like animals, must have some of this substance,
otherwise they will not be able to utilize the food
material in the soil. . . . Some very striking results
have been obtained with barley. Seven is usually
166 THE SPIRIT OF THE SOIL
the maximum number of shoots from barley plants
manured in the ordinary way. With bacterized
peat, however, as many as eighteen have been
obtained. This means that instead of seven ears
there would be eighteen to every seed originally
planted."
The Times, October 7, 1913, and May 21, 1914.
" Agriculture's debt to science is already large,
but ' bacterized peat ' — a new stimulant of plant
life produced at King's College, London, by Pro-
fessor W. B. Bottomley — promises to make the debt
incalculably larger.
" Tomatoes of quite a respectable size have been
grown from seeds set in pure sand, and watered with
an extract of this product. An eggcupful sprinkled
on the surface of the soil doubled the size of arum
lilies; carnations inoculated with eel-worm shook
off the pest with the aid of the ' peat,' and plants
of every kind grew more strongly, flowered more
profusely and with intensified colours, and quickly
became pot - bound through root - development.
Equally striking results have been obtained with
barley, wheat, and oats.
" The evidence already obtained in regard to the
efficacy of this new manure is reassuring. It has
been subjected to severe tests in the open fields as
well as in the laboratory, and in every instance its
effect has been pronounced. Professor Bottomley's
estimate of its value is more than confirmed by
those who have co-operated with him in practical
experiments under different sets of conditions and
with different crops. Chemical analyses of the pre-
pared peat show that it contains over fifty times as
much available food material as farmyard manure-
that is to say, i ton of the prepared peat is superior
to 50 tons of farmyard manure. This is a bold
FIG. 13
Eel-worm is a serious disease in many plants, but carnations are especially
liable to it. Both the carnations shown above (typical specimens of a
group experiment) were potted in soil known to be infected, with the
object of testing- whether humogen gave resistant powers to the
plant. The humogen-treated carnation, although infested in the
early stages, gradually grew away from the pest and developed into
a perfect plant. The untreated, although receiving various stimu-
lating plant-foods, reached the stage shown and then collapsed.
(The Royal Gardens, Kew.)
PRESS AND OTHER CRITICISM 167
claim to make, but it is based upon practical demon-
stration, and has not merely a laboratory justi-
fication.
' While the discovery is of more immediate
importance to horticulturists and market gardeners,
it is also of great interest to farmers. Should
present expectations be fulfilled, it would prove of
great service to those engaged in any form of inten-
sive culture. The primary need of the intensive
cultivation is an organic manure. The market is
fairly well supplied with salts or minerals, natural
or by-products, but it has been found that, although
these materials are useful, they cannot take the place
of a good organic fertilizer. The need of a new
vegetable manure is emphasized by the great
reduction in the quantity of town manure available,
owing to the substitution of motor power for horses
in street traffic. The market gardening industry at
a critical time in its development has suffered a
severe loss by the reduction in the supply of town
manure. Horticulture in its diversified forms, from
the smallest suburban plot to the Royal Botanic
Gardens at Kew, has shared in the resulting dis-
abilities; and although recourse has been had to
artificial materials, the chief effect has been to
demonstrate the serious disadvantage at which
intensive culture is placed without an adequate
supply of organic manure. The keen interest shown
in Professor Bottomley's treated peat reflects the
measure of the need of something to supplement the
diminishing quantities procurable from London and
other towns.
" As every farm is a producer of organic manure
in greater or less quantity, the need is not so pressing
in agriculture as in horticulture. It would be a
great gain for the former, however, if the supply of
home-made dung could be added to in so simple a
form as that prepared by Professor Bottomley.
168 THE SPIRIT OF THE SOIL
There are few who have as much as they could use
to advantage, with the result that they have either
to apply it sparingly or rely entirely on artificials for
a portion of the green crop and grass areas. Its
action being quicker than that of dung, it might be
thought that its stimulating energy was largely
expended in the first year. Recent tests made in
the laboratory, however, show that the treated
Kew soil after a season's growth still contains a large
amount of available food material, and that the
nitrogen-fixing bacteria are still active and capable
of producing further nitrogenous plant food. Ex-
perience alone can decide this and other important
points, but in the meantime it is satisfactory to have
evidence that an important addition is likely to be
made to our resources. It is interesting to know
that there is virtually no limit to the production of
the material. If there is any limitation it is in the
quantity of the moss available, since the bacterial
cultures are capable of indefinite multiplication."
CHAPTER XIII
HOW HUMOGEN IS APPLIED
How humogen is applied — Humogen suitable for all soils and all
crops — Analogy with air, carbon dioxide, and water — Im-
portance of aeration of soil and of presence of lime — Evils
of acidity — Test for presence of lime — Humogen in field
work. With herbaceous flower borders. With pot plants.
With grass — Liquid extract of humogen — Humogen used
with other fertilizers — Humogen and monocotyledons —
Humogen in agriculture — Its mixture with farmyard
manure — Results to be expected.
IN the course of previous chapters it has been an
easy matter to demonstrate the reasonableness of
the view that humogen is a substance suitable for
all plants and for all soils. Hitherto I have not
insisted on the point, as by stating the facts con-
nected with humogen, and explaining the mechanism
of its working, I have been confident that the con-
clusion would inevitably suggest itself to the minds
of all readers. At first sight the statement is apt
to be startling, and it is always so inevitably when
made to those who have not a clear idea as to the
nature of humogen. It becomes more intelligible
when one remembers that in adding humogen to the
soil one is doing nothing more than assisting Nature .
Humus of a better or worse quality is universally
present in all cultivated soils; the bacteria which
169
170 1 THE SPIRIT OF THE SOIL
effect the Nitrogen reactions are to be found either
themselves or replaced by similar ones in all soils in
which vegetation is growing, and, as in the peat, so
in untreateds oil, they are to be found fixing Nitrogen
and giving rise to the necessary auximones. All that
the humogen does in essence is to furnish the
healthiest possible strain of Nitrogen-fixing organisms,
to provide the bacteria with improved conditions
which favour their rapid growth and development,
to supply both them and the plants with an ideal
organic food that they can readily absorb, directly
or indirectly, to furnish an increased supply of
auximones, and in a very marked extent to improve
the texture of the soil. When, therefore, the state-
ment is made that humogen is a substance suitable
for all plants and for all soils, it is a statement com-
parable with such a one as that Carbon dioxide and air
and water are necessary for all plants and for all soils.
In this respect a comparison with water may
make the matter somewhat clearer. While water is
essential for all plant growth, its addition to a
water-logged soil would only be productive of harm,
a condition of affairs closely analogous with what
occurs when an excess of artificial or natural manure
is added to a soil that is already rich in the
material supplied. The analogy, so far as the peat
is concerned, is in no way comparable, for if humogen
is added to a soil already rich in foods the bacteria
grow luxuriantly, they increase in numbers, and
enable the plant to use to advantage the foods
already present.
In order to obtain the best results from the use of
HOW HUMOGEN IS APPLIED 171
humogen two facts have to be borne in mind. The
soil must, as in cultivation generally, be open to the
air, and its neutral or alkaline condition must be
insured by the presence of a sufficiency of lime. As
regards the soil texture it is unnecessary to write here,
because every farmer and every gardener is fully
aware of the importance of having an adequate air-
supply for the roots of plants, and recognise why the
ordinary methods of good cultivation have to be
employed. Experience in the past with nitrobac-
terine and with other fertilizers, however, has shown
that the necessity of the ground being adequately
limed has often not been sufficiently recognized.
No soil, it has been proved abundantly, can be
fertile unless it is free from acidity. In many
instances the neutral or alkaline condition of the soil
is obtained by general good cultivation and adequate
aeration of the soil (see Chapter IX., on the
chemistry of the soil). If the land after this treat-
ment remains acid, acidity can be removed by
dressing with quicklime to the extent of about £ ton
to the acre, or by dressing with air-slacked lime
to the extent of about a ton to the acre. The
general practice should be to apply the lime in the
late winter, or, with heavy clay soils, in the late
autumn or early winter. Lime is an essential soil
constituent, because it is a plant food, because it
renders the potash and phosphates in the soil
available to the plants, because it insures the alkaline
conditions necessary for bacterial activity, and
because of the mechanical effect it produces on soils
generally and especially on clays.
172 THE SPIRIT OF THE SOIL
Fortunately it is a simple matter for the farmer,
even if he is no chemist, to determine for himself by
a simple test whether or not the land is sufficiently
limed. To find out whether there is a sufficiency of
lime or not in a field, handfuls of soil should be taken
haphazard from all parts of the field. These should
be well mixed together, and a wineglassful of the
mixture should be poured into a tumbler, and the
tumbler three parts filled with water. A teaspoon-
ful of spirits of salts (Hydrochloric acid) should be
poured into the water, and if a sufficiency of lime is
present bubbles will be liberated in the same sort
of way that occurs when soda-water is poured out
from a soda-water syphon. If the water does not
bubble freely, there is a deficiency of lime in the
soil, and this must be made good before either
humogen can be usefully applied, or the land yield
a satisfactory crop. In some soils not greatly
deficient in lime basic slag may be used as a
substitute.
When humogen is required for field work on the
principles of intensive culture that obtain in market
gardens as contrasted with farm work, it should
be used in the proportion of 10 cwt. to the acre.
It should be spread over the ground, and then
ploughed or dug in so as to be well mixed with
the soil, and to lie some 3 to 6 inches below the level
of the ground. So far as possible it should be applied
a fortnight or three weeks before using the ground.
That single application should be all the treatment
required in the course of the year. In the event of
it not being possible to put on the humogen at the
HOW HUMOGEN IS APPLIED 173
time of digging, the same quantity may be top-
dressed and harrowed in at a later date when the
plants are in the soil. In that case the results would
be less certain for many reasons, an important one
being that the comparative dryness of the soil may
interfere with the proper growth of the bacteria.
In any case it should be borne in mind that it is
essential that the humogen should be got well into
the ground. Another practical point of great im-
portance is that the humogen and the lime must not
be applied together. After lime has been applied, at
least six weeks must elapse before the application of
the humogen, and the longer the intervening period
the better. Failing that, the soluble humates in the
humogen may be changed into insoluble Calcium
humate, which is not immediately available as a
plant or bacterial food, and there is a considerable
waste of nitrogenous food liberated in the form of
Ammonia.
The method of application described above is that
recommended generally for kitchen gardens, market
gardens, and orchards.
When it is desired to apply humogen to herbaceous
flower borders, to roses or sweet peas, the humogen
should be worked into the soil as described above
either in February or March. Eight or twelve ounces
should be applied to the square yard, because such
gross feeders will repay for the extra manuring and
throw a constant succession of blooms. Fruit
borders, with espaliers, cordons, vines, peaches,
nectarines, strawberries, etc., require the same
treatment as the above; but if the plants are being
I74 THE SPIRIT OF THE SOIL
grown under glass, the ground should be watered
well after application.
In the case of pot plants generally, including
cucumbers, melons, and marrows, the compost
suitable for the requirements of the plants should be
used, omitting leaf mould. The best results so far
have been obtained by using i part of humogen to
9 parts of compost.
For grass, lawns, golf-greens, and tennis-courts,
humogen should be applied in February as a
top - dressing, at the rate of 4 ounces to the
square yard, or approximately 10 cwt. to the
acre.
A valuable liquid stimulant can be obtained by
soaking a pint of humogen in 2 gallons of warm
water, allowing it to stand overnight, and using the
liquid undiluted when watering. Such a liquid has
all the advantages of a Nitrogen stimulant without
the drawbacks. In applying the liquid extract of
humogen the grower is enriching the soil with
bacteria, which will continue yielding available
Nitrogen and auximones. By this means the plant
is developed completely, and there is not simply a
stimulation of leaf development as occurs with
nitrate stimulants. There is very seldom any danger
of the plant being injured by even extreme strength
of the liquid. It can be given as dark coloured as
black coffee, and in that concentration it is/most
effective if a powerful stimulant is required. As is
the case when the humogen is applied in other
forms, free and perfectly balanced growth is pro.
moted.
HOW HUMOGEN IS APPLIED 175
Good results can be obtained by using humogen
with other fertilizers, particularly if they are not
acid in character, as is the case with many artificial
manures and fresh dung. Old rotted stable manure,
when mixed with a twentieth part of its bulk of
humogen, is a valuable fertilizer, easily applied, and
combines the good qualities of both dung and
humogen. There is no reason, however, why
humogen should not be used alone without any other
fertilizer, and so far experiments have demonstrated
that alone it will do all that dung and artificial
manure, either separately or together, are able to
effect. A basis of dung or other bulky organic
manure has distinctly beneficial effects on the
mechanical texture of the soil apart from any
manurial value that it may have. Its presence is
definitely advantageous in extreme soils — that is,
heavy clays or light sands — and well worth con-
sideration.
It should be noted carefully that when humogen is
applied to bulbs and corms only i part of humogen
to 20 parts of soil should be used. In all experi-
ments carried out with monocotyledons it has been
found that one-half of the dressing required for
ordinary plants is sufficient.
In considering the application of humogen to
agricultural conditions it is not possible to speak as
yet with the same degree of certainty as it is in
horticultural and glass work. The present year,
for instance, with its seven weeks of continuous
drought, has resulted in many field experiments
giving, so far as can be seen at present, nega-
176 THE SPIRIT OF THE SOIL
live results. It had been hoped that the infor-
mation gained this year would have made it
possible to lay down definite rules as to quantities
advisable in varying conditions, and so forth. At
present, unfortunately, one has still to be guided by
the experience gained in the market gardens. A diffi-
culty, however, that will occur to every practical
farmer can at once be stated and met. Inevitably a
large quantity of farmyard manure will be produced
year by year under present farming conditions, and
the supply will perhaps reach the half of all the
manure required on the farm. The question natur-
ally arises as to what is to be done with this manure
if humogen is used. Probably the best solution
would be to spread this over the whole farm, and to
supplement it with humogen. In this way the level
of the fertility of the soil would be raised to a higher
standard than has obtained in the past. Five hun-
dredweights of humogen to the acre applied in the
spring, top-dressed and harrowed in, should greatly
increase the yield of the farms if the results obtained
in small plot experiments hold good when the treat-
ment is transferred to the farm. Up to the present
the results are indefinite, and do not bear tabulation.
The results given in the appendices, with rare excep-
tions, are of a market garden or greenhouse order,
but it is hoped in later editions of this book that it
will be possible to give definite statements as to the
amounts of material used and so forth. Generally
one may advise the application of from 5 to
10 cwt. to the acre for roots generally, potatoes
especially responding well to the larger amount.
HOW HUMOGEN IS APPLIED 177
Experiments now in progress seem to justify the
anticipation that the crops will be greatly increased.
It is perhaps worth noting again here that under
experimental conditions wheat and other cereals
have responded well to humogen treatment, showing
improved tillering, larger ears, and increased growth
of the straw.
V
CHAPTER XIV
GENERAL RESULTS
Experimental character of horticulture and agriculture —
Benefits from inoculation — Selection of results — Difficulties
of exact measurements — Need for farm experiments —
Three arguments justifying them — Experiments on apples.
Asparagus. Asters. Auricula. Balsam, Barley. Beans.
Beetroot. Begonia. Broccoli. Brussel sprouts. Cabbages.
Calla. Carnations. Carrots. Cauliflowers. Celery. Chrys-
anthemums. Clover. Coleus. Cordyline. Cotton. Crassula.
Cress. Crocuses. Crotons. Cucumbers. Cyperus.
Daffodil. Dahlias. Daisies. Ferns. Fuchsia. Geranium.
Gloxinia. Grass. Grevillea. Hippeastrum. Hyacinths.
Iresine. Iris. Isoloma. Jacobinia. Lantana. Leonitis.
Lettuces. Lilium. Maize. Marrows. Mustard. Nas-
turtium. Nerium. Nicotiana. Onions. Orchids. Parsnips.
Peas. Potatoes. Primula. Pyrethrum. Radishes. Rhu-
barb. Roses. Schizanthus. Scutellaria. Streptocarpus.
Sweet peas. Tomatoes. Turnips. Wallflowers. Wheat.
THE contention of the present volume is that soil
inoculation scientifically carried out will greatly
increase the yield of the land that is already under
cultivation, that it will bring into cultivation large
tracts of land that it has hitherto not paid to culti-
vate, and that by the stimulation of plants it will be
possible to bring fruit and flowers to maturity earlier
than can be done by other means. In the present
chapter I propose briefly to indicate the results that
experience has shown can be achieved by the grower.
178
GENERAL RESULTS 179
I am not pretending that such results will always
follow on the application of bacterized peat. How-
ever careful the directions given, it is inevitable that
from time to time mistakes will be made in the
methods used for employing the peat, and the com-
plexity of Nature is such that special conditions
will inevitably arise where results will fall short of
anticipation. The practical grower and the amateur
gardener hardly need to be told that both horti-
culture and agriculture are still, despite centuries
of accumulated experience, to a large extent in the
experimental stage, and it would be unreasonable
to expect that after ten years of experimental work,
much of it perforce done in the laboratory and the
hothouse, there can be the same degree of certainty
which may fairly be expected from methods which
have stood the test of centuries.
It has not been an easy matter to select typical
results from the evidence available. Experiments
have been tried with success on many species other
than those of which mention is made, but I have
attempted to select those species which are more
commonly under cultivation. At the outset I would
state frankly that the presentation of the results is
faulty. Scientific methods would require the state-
ment of exact comparative weights and measure-
ments with standardized tests of colour, and so forth.
The conditions under which such work can be done,
however, cannot readily be complied with. The
horticulturist and the farmer who in the past years
have been willing to give a trial to bacterized peat
are inevitably men who have other business to
i8o THE SPIRIT OF THE SOIL
attend to beside that of undertaking the extremely
difficult work of accurate measurement. To have
carried such work out on a satisfactory scale from
the standpoint of exact science would have required
a large number of highly trained workers, and even
had that policy been pursued there would have been
people to raise the objection that the results were
results obtained by the laboratory man, and not
by the practical worker. Several cases where exact
measurements have been taken will be found re-
corded in Appendix B, and as regards the results
which follow here the statement may be made that
authority can be given for each generalization made.
In some cases the deductions are based on a single
experiment, but in most instances the claims put
forward can be endorsed by evidence obtained from
several growers.
A characteristic of supreme importance from the
material standpoint will be noted. The majority of
the results refer to experiments carried out by horti-
culturists rather than farmers. So far bacterized
peat has been tested chiefly by the horticulturist,
the man who stands midway between the experi-
mental botanist and the farmer. The value of soil
inoculation effected by means of bacterized peat
has been proved conclusively in the laboratory.
The experiments conducted at Kew Gardens and
those carried out by horticulturists and market
gardeners, both under glass and in the open, have
endorsed the laboratory experience. Such experi-
ments as have been made under farming conditions
indicate that there is every reason to believe that
GENERAL RESULTS 181
the results obtained in the laboratory and the field
are also available to the farmer, and the main object
of the present book will have been attained if it
induces those who alone are in a position to carry
out these experiments on a grand scale to extend the
scope of our present experience. Three arguments
should serve to convince them : The first, that the
experiments have proved successful both in the
laboratory and market garden ; the second, that the
American Board of Agriculture are encouraging the
farmers in America to make use of inoculation even
on lines only slightly modified from those which a
few years ago were partially successful in this
country ; and the third, that the use of the bacterized
peat, even if it were not to benefit the crop, is
incapable of doing it harm.
For purposes of convenience I have thought it
simplest to describe the experiments in alphabetical
order, and to save space I have compressed the
results into the smallest possible compass. It should
be borne in mind that the nature of the treated peat
is such as to make it valuable in the case of all plants.
Except where otherwise stated, control plants
have received the manure or fertilizers commonly
accepted as suitable for them, while often the best
known treatment has been given.
APPLES. — Increased vigour of growth followed
treatment. The wood was stronger and riper. The
foliage was a rich dark green. There was an average
gain of i£ ounces on each fruit, and the fruit ripened
about a fortnight earlier than on untreated trees.
In the second year there was no further application
182 THE SPIRIT OF THE SOIL
of the treated peat, but the trees showed a robust
health, and were more heavily laden than usual with
fruit. The experiments were tried with the Blen-
heim Orange and Cox's Orange Pippin.
ASPARAGUS. — The tests were made with aspara-
gus seedlings. At the end of the season the growth
was such that the plants were a year nearer bearing
than those which had not been treated, to judge
by the increased size of the roots. The foliage
of the treated plants was of better colour and
substance.
ASTERS. — The seeds sown in the soil treated with
bacterized peat gained from the seed-leaf stage until
the time of flowering, when the plants were more
than double the size of those which had not been
dressed with the peat. They formed bouquets of
flowers averaging 5 inches across (Comet Aster), as
against 4 inches in plants not treated. The foliage
and the stems were both stronger and larger.
AURICULA. — Increase in growth followed treat-
ment, and the plants treated were quite free from
woolly aphis, while those which had not been treated,
though in the same house, were attacked.
BALSAM IMPATIENS. — The results obtained with
Balsam were very striking. One object of the
experiment was to determine how far the plant,
notoriously liable to eel-worm, would be rendered
immune. Experience showed that there were no
signs of eel-worm among the treated plants, whereas
those not treated succumbed to the disease.
BARLEY. — Laboratory experiments conducted
with barley were very promising. There was a deep
FIG. 14
French runner beans as grown in Guernsey. The plant on the right
was treated with humogen and yielded more beans than the plant
on the left. The total increase of the two such treated plants over
the two such untreated plants was S6'5 per cent.
(Grown by Mr. Holmes, Tuckswood Farm, Norwich.)
GENERAL RESULTS 183
green colouring to the leaves, and the culms were
much stronger. The tillering was better.
BEANS, RUNNER. — The treated plants were earlier
above ground than those not treated. Their growth
was more rapid, and they attained a greater height
and developed enormous healthy green leaves, in
some cases as large as dinner-plates. In some
instances the pods were as much as 15 inches long,
while they averaged about 12 inches. They retained
their vigour when the untreated plants yellowed
off, and the yield was increased by 20 per cent, or
more.
BEETROOT. — This root responds quite exception-
ally well to humogen treatment. A gain of 50 per
cent, over other fertilizers has been the rule rather
than the exception, this gain being maintained with
turnip and long beet, and also with the sugar beet.
The quality of the beet has been found to be greatly
improved. The roots, although very much larger,
were excellent in colour and flavour, woolliness being
conspicuous by its absence.
BEGONIA. — The peat-treated plants were more
robust and heavier flowered than those receiving
soot or guano.
BROCCOLI. — The main difference between the
broccoli and the cauliflower is the superior power of
resistance of the former vegetable to cold. Both
respond admirably to treatment with peat (see under
Cauliflower), and the results obtained with broccoli
were closely comparable with those got on cauli-
flower. The fact is especially interesting as showing
that the effect of the treatment is to stimulate the
i84 THE SPIRIT OF THE SOIL
plant into active growth without producing a soft,
sappy plant that would succumb to frost. The
effect was to make the plants resistant, sturdy, and
vigorous.
BRUSSEL SPROUTS. — In this instance the effect of
testing peat against both artificial manures and dung
was to give an increased yield of better quality.
The buttons were hard, firm, and closely set, giving
a much greater average yield per plant. The plants
themselves grew taller, and the flavour was dis-
tinctly improved.
CABBAGES. — Growth was earlier and sturdier.
The plants showed a rich bluey green, denoting
perfect health. The hearts were larger, harder, and
crisper than in untreated plants. They were ready
for market earlier.
CALLA. — In calla the effect was very noticeable.
There was great profusion of bloom, and the root
action was excellent. The foliage was a rich deep
green, and the blooms were splendid. A top-dressing
of i ounce of humogen on a 10-inch pot full of food
more than doubled the growth in a month.
CARNATIONS. — One carnation specialist has had
plants 13! inches high in thumbs. They were then
still growing, and were the equal of plants which had
been grown in 3-inch pots, but without the peat.
Tested against various carnation specialities, the
peat-treated plants gave much more satisfactory
growth. They broke freely and flowered abun-
dantly. The plants grown in the humogen resisted
eel-worm, while those without it succumbed. One
of the principal prizes at Chelsea and Holland House
GENERAL RESULTS 185
this year (1915) was awarded to carnations grown
with humogen.
CARROTS. — The yield from ground treated with
peat, as compared with dung, showed an increase of
28 per cent., and of 20 per cent, as compared with
artificial manures. The roots were clean, straight,
and of good colour. The tops were not so big as
might have been expected, considering the size of
the roots, a point that should be borne in mind by
users of treated peat who wish to estimate the
progress of plants under treatment from week to
week. The remark applies generally to all root
crops, including potatoes.
CAULIFLOWERS. — There was a 10 per cent, im-
provement shown by plants treated over plants not
treated. The heads formed earlier, were closer, and
generally more satisfactory.
CELERY. — The sticks of treated celery were 20 per
cent, larger than those untreated, and were hard and
nutty. They were pulled three weeks earlier, and
the crop was altogether much heavier. The colour
of the plants was a rich, dark, glaucous green, and
the stems were free from frothiness. Owing to the
increased vigour and hardier nature of the plants,
they were much less affected than the untreated
plants by early frosts.
CHRYSANTHEMUMS. — The leaves of the treated
plants were large, well formed, thick, and of a dark
green colour, while the foliage was retained from
the base upwards throughout the season. Growth
was free, abundant, and sturdy, and there was a
maximum number of side-breaks. In the blooms a
i86 THE SPIRIT OF THE SOIL
striking feature was the improved colour and sub-
stance of the petals, while the flowers of treated
plants retained their freshness and beauty a fortnight
longer.
CLOVER. — Clover is stimulated in a very marked
manner, the plant spreading and increasing in size
rapidly. It very soon acquires sufficient strength
to displace its neighbours.
COLEUS in variety. A striking feature apart from
the increased growth was the extraordinary intensity
of the colours in the foliage. It has always been held
generally that while an abundance of stimulating
food produces growth, it sacrifices variegation and
colour. With bacterized peat both increase in size,
and very vivid colouring were obtained. Similar
results were obtained with abutylon. (Photo, p. 143.)
CORDYLINE DRACENA. — The effect of humogen on
small plants of this species was to produce a plant
fit for the market in two months, whereas under
ordinary treatment six months would be the usual
time necessary. In the experiments made the root
action was particularly vigorous.
COTTON. — The plants grew taller, and they were
very markedly thicker and stronger stemmed. The
leaves were larger, and the plants generally had
every appearance of being stronger and healthier.
The root formation in the pots was very notice-
able.
CRASSULA COCCINEA. — As with other potted
plants, the points particularly noticeable were the
perfectly balanced growth, the profusion of bloom,
and the increased root action. Foliage responded
GENERAL RESULTS 187
well to the treatment, and the colour of the blooms
was intensified.
CRESS. — The effect of the treated peat on cress is
excellent, and this plant is admirably adapted for
showing the effect of peat experimentally on a small
scale. In the opinion of one grower the improve-
ment in size, flavour, and substance was such as to
justify 100 per cent, increase in the price charged-
To repeat the experiment it is only necessary to sow
cress seeds in a shallow box containing ordinary
garden soil, and to compare this with a box under
similar conditions with treated peat added in the
proportion of i : 12. Germination may be slightly
delayed, but the ultimate effect is assured. The
second cutting of the treated cress has in many cases
been heavier than the first cutting of the untreated
cress.
CROCUSES. — Foliage and flowers were greatly im-
proved. The resulting corms were bigger and
heavier, giving promise of better results in the fol-
lowing year.
CROTONS. — The plants were much finer, and the
colour in the foliage was greatly intensified. Root
action was very strong. (Photo, p. 159.)
CUCUMBERS. — Twenty days after planting the
cucumbers which had been peat-treated, cutting
commenced, 72 cucumbers, weighing 73 pounds,
being cut from 18 plants before the untreated plants
yielded a fruit (June 7). A fortnight later 119
cucumbers, weighing 119 pounds, had been cut
from the treated, as against 58 cucumbers, weighing
51 pounds, from an equal number of untreated
i88 THE SPIRIT OF THE SOIL
plants. The fruits were heavier; the foliage was
slightly smaller, but of a much deeper green. The
root action was very vigorous, top-dressings being re-
quired much more often than for the untreated plants.
CYPERUS VEGETUS. — There was three times as
much growth and bloom. The treated plants were
still in full vigour when the control plants, in a com-
plete soil mixture, were showing signs of starvation.
DAFFODIL. — Stronger growth was observed, and
there were 45 per cent, more blooms from the same
number of bulbs. The flowers stood well above the
foliage.
DAHLIAS. — -The effect on the growth of dahlias was
very striking. Although growth was so strong the
flowers were thrown well away from the foliage.
The colours of the blooms had a glowing richness,
and in their number and quality fully corresponded
with the growth.
DAISIES (Chrysanthemum Max). — The flowers were
larger, earlier, and better, and cutting commenced
a fortnight earlier.
FERNS (Adiantum, Pteris, Asparagus Plumosa
and Sprengeri). — Ferns respond very quickly to
treatment, and produce good saleable plants in a
third of the time usually taken. Experiments con-
firming this result — as in many of the other cases
here quoted — have been in progress for three years.
FUCHSIA. — The usual characteristics of the effect
of humogen on pot plants have been well marked in
the case of the fuchsia — the well-balanced sym-
metrical growth, profusion of bloom, energetic root
action, rich foliage, and intensification of the colour
GENERAL RESULTS 189
of the bloom. The pyramidal formation of the
plants has been very noticeable. In one typical
series of experiments the plants bloomed six weeks
after potting at the end of May, and continued in
flower until October.
GERANIUM. — Several tests have been made with
geraniums, and it has repeatedly been found that
the treated plants continued growing and blooming
when plants without the peat were starved. One
grower has reported that he has by means of the
peat been able to obtain geraniums by May or June,
selling them at 45. a dozen, whereas under former
conditions he used to obtain only 2s. 6d. a dozen.
GLOXINIA. — These made excellent glossy foliage,
and flowered profusely. The plants generally were
better and bigger in every way.
GRASS. — In connection with golf-greens, cricket-
pitches, and lawns, humogen has been tried against
a mixture of malt culms, soot, and ammonium sul-
phate, and in every way the peat has proved superior.
The grass becomes a beautiful dark green, the clover
in it is thickened, and a much better bottom is devel-
oped. A well-known golf professional has described
how a week after the application of the peat the
portions of greens treated could easily be distin-
guished from a long distance off.
GREVILLEA ROBUSTA. — After treatment the plants
grew so rapidly that they became too big for the
greenhouse. A notable feature was the way in
which the plant branched, breaks occurring at al
axils, and resulting in a dense mass of foliage.
(Photo, Frontispiece.)
I9o THE SPIRIT OF THE SOIL
HIPPEASTRUM. — Seedlings by the end of the
season had made bulbs two and a half times as heavy
as in the case of untreated plants. They were
therefore so much the nearer by that extent to the
flowering stage.
HYACINTHS. — Increase in the root action was well
marked. The foliage was rich in colour. The flower
spikes were heavier, and both colour and scent were
strongly intensified. The bulbs were heavier.
(Photo, p. 91.)
IRESINE LINDENI. — The purplish red attained in
the foliage was very striking. The growth obtained
was less remarkable, but the colouring was far more
intense, deeper, and richer.
IRIS HISPANICA. — Growth was more vigorous ; the
flowers were bigger, and matured a week earlier.
ISOLOMA. — Fine healthy plants were obtained far
larger than in the case of non-treated plants. Those
receiving humogen showed greatly increased root
action, much improved foliage, intensification of
flower coloration, and a notable symmetrical
development.
JACOBINIA. — Results were obtained similar to
those in the case of isoloma, but owing to the intensi-
fication of colouring the blue flowers made a striking
picture against the dark green foliage.
LANTANA SABRIFOLIA. — The rapidity of growth
obtained without spoiling balance was very marked.
The plants were more than double the size of those
not treated.
LEONITIS LEONURUS. — Symmetry, strongly pro-
moted root action, intensification of colour of foliage
FIG. 15
The maize plant was one of the earliest on which auximones were
tested. All the plants shown above were grown in sterilized sand
(washed silver sand). The plant on the right received nothing but
distilled water. The middle one received a complete chemical diet
(Detmer's). The one on the left received Detmer's +0*35 part per
million of the Silver fraction derived from the Phosphotungstic
precipitates obtained from bacterized peat. The photograph had
to be taken at an early stage, as the plant grown with distilled water
was beginning to die.
(Botanical Laboratories, University of London, King's College.)
GENERAL RESULTS 191
and flower, and perfectly balanced growth, with
increase in size, were well marked in the treated
plants.
LETTUCES. — A series of experiments carried out
in a dry spring showed a superiority of the peat over
dung of 123 per cent., and of the peat over artificial
manure of 176 per cent. The plants were markedly
good-looking, and hearted well.
LILIUM HARRISII. — In addition to showing the
characteristics usually following the use of peat with
pot plants there was an average increase of 8 inches
in height, though the pots were smaller than those
ordinarily used. The number of blooms per plant
was usually six or seven.
MAIZE. — Remarkable results were obtained with
experiments conducted in sand culture with maize to
testthe effect of auximones. The weights of the dried
plants under different treatment were as follows:
Grammes.
Sterilized sand and distilled water . . 66
Sterilized sand and Detmer's solution . . 215
Sterilized sand, Detmer's solution, and
phosphotungstic fraction from humogen
(17 parts in 1,000,000) . . . . . . 255
Sterilized sand, Detmer's solution, and
Silver nitrate fraction from bacterized
peat (0-35 part in 1,000,000) . . . . 325
MARROWS (Bush). — When marrows were treated
with artificial manures the average weight of the
fruits obtained per plant was 16 pounds 5 ounces.
When treated with peat the fruits weighed 37 pounds
ii ounces. The plants fruited a week earlier, and
continued bearing after the others.
MUSTARD. — Peat treatment gave an increased
yield of 174 per cent. The leaves were darker all
192 THE SPIRIT^OF THE SOIL
the time the plants were growing and had thicker
stems, the effect being most marked when the crop
was ready to cut.
NASTURTIUM. — When peat was used in small
quantities the plants improved in every respect, but
when a full dressing of peat was used the plants
became too vigorous, developing a huge foliage that
concealed the flowers.
NERIUM OLEANDER. — In addition to increased
root and foliage development, and a marked increase
in the size of the plants, the flowers themselves were
larger and more numerous, and showed a striking
increase in colour.
NICOTIANA (Tobacco Plant). — The plants were
stouter stemmed, broader leaved, and taller.
ONIONS. — In one experiment treatment with the
peat was followed by an increase of 41 per cent. In
another experiment, when no manure was used as a
control, the treated plants showed an increase of
no per cent., and where dung was used as a control,
of 46 per cent. The plants grown in soil mixed with
humogen, as compared with those that had received
dung, had much smaller tops, the necks were
thinner, and the bulbs harder and bigger, and
they proved better keepers.
ORCHIDS (Veitchii Calanthe). — The plants pro-
duced spikes earlier and heavier than those which
had not received peat.
PARSNIPS. — Three drills were dressed with humo-
gen this year (1915), and grown against eight drills
undressed. Those treated with humogen are much
more forward and growing more evenly.
GENERAL RESULTS 193
PEAS. — In one of many experiments there was a
31 per cent, gain in weight of the pods pulled for
eating. The plants were taller, and the pods were
both larger and more numerous. In another experi-
ment on peas grown for seed three rows untreated
gave 18 pounds of dry seed, while three treated rows
gave 28 pounds of seed, an increase in weight of
55 per cent., representing to the grower a money
gain of i8s. 3d.
POTATOES. — Compared with no manure, artificial
manures and dung, peat has given an increase in
potatoes over no manure of 123 per cent., over arti-
ficial manures of 75 per cent., and over dung of
41 per cent. These results were obtained in a light
sandy loam in 1913, the land not having been
previously cultivated for nine years. In 1914 the
same ground treated with humogen gave an increase
of 59*5 per cent, over land not manured. A part of
each of the plots manured in 1913 was left un-
manured in 1914. The land which had received arti-
ficial manures showed an increase of 27 per cent,
over the unmanured land, the peat-treated land
showed an increase of 83*3 per cent., while the land
that had received dung showed an increase of 37*7
per cent. The treated peat appeared to leave the
land as fertile the second year as in the season of
application.
PRIMULA (Malacoides, Kewensis, Obconica, etc.}. — -
All varieties of primula tested responded equally
well, the plants in each case showing 100 per cent,
superiority. The flowers were more prolific, and
individually larger and better coloured.
13
194 THE SPIRIT OF THE SOIL
PYRETHRUM. — Cutting was ten days earlier. Stems
were markedly longer, and the characteristic feathery
foliage better developed.
RADISHES. — A striking result has been obtained
with radishes grown in soil as against the same soil
and humogen. Two rows were grown against each
other. The weight of the best twelve plants in the
humogen row was 6| ounces ; of the second best dozen
5^ ounces. Only a dozen weighable radishes were
obtained from the untreated row, and they weighed
only 3f ounces. (Photo, p. 194.)
RHUBARB. — Early this year (1915) a very small
dressing of peat was given to a portion of a plot of
growing rhubarb. By June 5 the treated portion
was very much better than the untreated. It was
ready for pulling earlier, and growth continued
longer, stalks being pulled from it after growth had
ceased in the other part of the plot.
ROSES. — Excellent results have been obtained
with roses. The plants increased in vigour, and the
healthiness of the foliage and the colour of the
blooms were intensified. So well marked is the latter
quality that two beds of Dean Hole, one of which
was treated and the other untreated with the
peat, appeared as if stocked with two distinct
varieties of roses. The grower has secured five first
prizes in open competition this year. In one case
the better colour was the deciding factor between
first and second prizes.
The intensification of the colour is especially
marked in the case of Marechal Niel. In the hands
of at least one well-known market grower humogen
FIG. 1 6
The radishes on the left were treated with humogen and soil, those on
the right being grown in soil alone. The best dozen of the humogen-
treated plants weighed 6| ounces as against 3! ounces from the
untreated. The second best dozen of treated plants weighed 5^
ounces, while in the other case the second dozen plants were not
weighable.
(Mr. Holmes, Tuckswood Farm, Norwich.)
GENERAL RESULTS 195
and soil is giving considerably better results than
his own soil mixture.
SCHIZANTHUS. — The plants proved finer and
heavier flowered, and the individual flowers were
larger than the controls.
SCUTELLARIA CosxARiCANA. — The plants were
grown with humogen and soil as against a complete
manure. There was differential improvement in the
case of the humogen-treated plants in root develop-
ment, nature of foliage, symmetry, and size. The
increased sturdiness of growth was notable, while
the flowers were distinctly heavier and earlier.
STREPTOCARPUS. — Excellent growth was made
with glossy foliage and abundance of flower.
SWEET PEAS. — The effect of humogen on sweet
peas is marked. There is increase in growth, height,
and length of flower-stems, and intensification in the
colour and veining of the bloom. The foliage is
healthier looking and deeper in tint. The Bide
Challenge Cup was won this year (1915) by an
amateur at the National Sweet Pea Society Show by
blooms from plants grown with the aid of humogen.
The second prize was also won by a grower who had
used humogen. The same grower (who got first
prize) has won at different shows this year five first
prizes and one second prize, in every case with
humogen-treated plants. In two gardens where
humogen was used streak was absent, though un-
treated plants collapsed from the disease.
TOMATOES. — Stimulation of growth is very marked
with tomatoes. Rapid growth takes place, but
plants remain short- jointed and small foliaged,
196 THE SPIRIT OF THE SOIL
setting and fruiting heavily. According to reports
received treated crops have frequently given double
the yield of untreated. Several growers state that
ripening is advanced by from three to four weeks.
(Photo, p. 145.)
TURNIPS. — Several experiments have been made
with turnips. In one of these, in poor soil, peat
increased the yield by 100 per cent, over no treat-
ment, by 47 per cent, over artificial manures, and
26 per cent, over dung. In another experiment
humogen increased the yield by 121 per cent, over
no manure, while farmyard manure gave an increase
of 67 per cent, over none, and artificial manures
gave an increase of 52 per cent, over none.
WALLFLOWERS. — Fine bushy plants resulted from
treatment. Masses of fibrous roots were formed
which transplanted well, yielding plants that were
perfect mounds of bloom.
WHEAT. — Wheat treated on an experimental
scale in a market garden with humogen, and
compared with the untreated garden soil, was taller,
stronger, and greener than the non-treated wheat.
It was well in spike on June 15, and the tillering was
better, averaging twenty-three ears as compared with
fifteen. The humogen was applied on the scale of 5 cwt .
to the acre, and used as a top-dressing. The culms
were very much heavier, and the untreated plants
were in comparison very yellow, dwarf er, weaker, and
more backward in bloom. The plants showed a gain
of a foot in height, and the ears were i£ inches longer
and fuller. Unfortunately both treated and untreated
plants were beaten down during one of the heavy
storms, and the experiment could not be concluded.
CHAPTER XV
HINTS AND EXPERIMENTS
IN this chapter I have collected together the points
that must be borne in mind by those who wish to
test humogen experimentally, expressing them in the
briefest possible form. I have suggested a few model
experiments as a guide, but naturally the most
interesting results will be obtained by those who
design and carry out experiments for themselves.
In conducting experiments every fact observed
should be carefully noted down at the time, and the
progress of experiments should be recorded by photo-
graphs at frequent intervals. All dates, especially
such as that of the first appearance of the shoot above
the soil, of the first bloom and of the first matured
fruit should be noted. Invariably there should be
control experiments — that is, experiments in which
plants have been treated without any other differ-
ence except for the omission of humogen. Valuable
results can also be obtained by testing humogen
against other manures.
MISTAKES TO BE AVOIDED.
Don't expect humogen to do all the work of the
gardener. The better the cultivation, the better the
results.
197
198 THE SPIRIT OF THE SOIL
Don't attempt to grow plants out of their season
in the open.
Don't attempt to grow plants in sour soil. Lime
must be given in this case to render the soil neutral
or slightly alkaline.
Don't give too much water. Pot plants do not
require watering until the pots ring when struck.
Don't judge the water condition of the soil by the
surface.
Don't overcrowd the plants, but leave room for root
growth.
Don't use humogen in greater concentration than
i part in 10, or you will waste the material.
Don't be disappointed if a slight retardation is
evident at first when using sterilized soil.
Don't leave bags of humogen where they can get
wet. An ordinary dry garden shed is a suitable
place.
Don't be afraid that the humogen can injure plant
growth.
Don't be afraid of the bacteria in humogen. They
are perfectly harmless.
Don't attempt to grow plants in rooms with coal
fires or gas.
POINTS TO BE REMEMBERED.
One part of humogen to ten of soil gives the best
results, with the exception of bulbs (monocotyle-
dons), when i in 20 should be used.
Mix up your compost in accordance with the
requirements of the varying species, using humogen
instead of leaf mould and dung.
HINTS AND EXPERIMENTS 199
When growing plants in moss and humogen ex-
tract sterilize the moss.
When possible mix humogen with the soil.
Treat the plants with humogen from the seed-leaf
stage.
When using moss, water once a week with a coffee-
coloured extract of humogen. Use plain water at
other times.
When using as a top-dressing incorporate the
humogen as deeply as possible in the soil.
When preparing the ground lightly dig in the
humogen some few days before sowing.
Apply humogen to the land early, so as to give
the bacteria time to multiply in the soil while it
is moist.
On poor ground use at least 10 cwt. per acre.
For kitchen garden crops it pays to use liberally.
Eight to ten pounds per rod should suffice. Roses
and flower borders the same.
If you wish to co-operate in advancing soil bac-
teriology keep accurate accounts of all you do, and
especially measure the humogen employed and the
resulting produce. The model experiments are a
guide how to keep results.
Remember if you don't get results to write direct
to Mr. Alfred Machen, 48, Frances Road, Windsor,
giving full details of what you have done. Either
failure is due to avoidable error, or your experience
will help to advance knowledge.
200 THE SPIRIT OF THE SOIL
MODEL EXPERIMENT I.
Radishes.
The French breakfast radish is a convenient plant
for a preliminary experiment. Use two small boxes
about 3 inches deep. Fill one with your garden soil
or loam obtainable from a seedsman. To the other
box add humogen, using one-ninth of the bulk of the
soil (conveniently measured by a teacup) . Mix the
humogen and soil well. Plant the same number of
seeds in each box about ij inches apart and about
J inch deep. Water thoroughly, interchanging the
position of the boxes weekly, so as to insure similar
treatment. A window-ledge or a site in the open
garden is suitable, but in the former case care must
be taken with the watering, as in such conditions
the soil dries rapidly. The best plan is to plunge
the box up to the edge in the soil, when watering
will be reduced to a minimum.
The radishes should be pulled when ready for
eating from both boxes at once, and the following
points noted :
1. Number of plants in each box.
2. Weight of complete plants in each box.
3. Weight of edible portion in each box.
4. Divide weights in each box by number of plants
in each box to get a comparison of the average weight
of the roots.
5. Notice the quality as well as the quantity.
6. Determine percentage increase by multiplying
the weight in the box treated with humogen by 100.
HINTS AND EXPERIMENTS 201
Divide this by the weight of the untreated plants,
and subtract 100 from the answer.
Thus, to work out the percentage increase in the
humogen-treated beans obtained by Mr. Holmes,
and described in the chapter on " The Testing of
Humogen," one would calculate as follows:
x 100 _ 151 (half ounces) x 100
8J 8 1 (half ounces)
.-. Percentage increase = 186*5 ~ *oo = 86*5 per cent.
NOTE that experiments with radishes can be con-
ducted in the open at any time between the middle
of March and the first week in September. The
plants can be grown in a greenhouse or in a light
and airy room at any time of the year.
MODEL EXPERIMENT II.
Primula (any Variety).
Primula plants ready for their final potting are
easily obtained in the early autumn. The new pots
should be filled (i) with good potting soil, as recom-
mended by nurserymen from whom it may be
obtained ; (2) with some rich mixture such as that de-
scribed in the chapter on " The Testing of Humogen,"
as used at Kew, or according to what the experi-
menter regards as the best possible obtainable;
(3) the good potting mixture used for (i), with one-
ninth of humogen well mixed. From this time
ordinary cultivation is all that is necessary.
202 THE SPIRIT OF THE SOIL
NOTE. — (i) The comparative growth of the plants
at various stages.
(2) The development of the root.
(3) The colour and thickness of foliage.
(4) The date at which blooms first appear.
(5) The date at which the plants stop blooming.
(6) The number of blooms obtained from each
plant throughout the season.
(7) The size and colour of individual blooms.
MODEL EXPERIMENT III.
Moss Culture.
Sterilize any variety of moss by heating it in steam.
The moss should not be boiled in water. The best
rough way of sterilizing the moss is to cover the
bottom of a large saucepan with \ inch of water.
Then cover the bottom of the saucepan 2 inches deep
with well-broken clean road-metal, or some similar
substance to prevent the water from reaching the
moss. Fill the rest of the saucepan with the moss,
and boil well for a quarter of an hour. Avoid heating
to dryness, and if necessary add water. The sauce-
pan should be covered. Better still an ordinary
kitchen steamer should be used. Nearly any plant
can be used for moss culture, but the following are
recommended : Potatoes, bulbs of all sorts, ferns.
All that is necessary is to water the plant once a
week with humogen extract. Use the proportion of
i pint of humogen to 2 gallons of water. To prepare
the liquid mix the humogen in a jug with water not
warmer than can easily be drunk. Stand over
HINTS AND EXPERIMENTS 203
night, and decant the liquid in the morning. Water
the moss once a week with humogen extract, and
in between times with ordinary tap-water.
NOTE.— (i) The weight of the bulb when planted
and its weight at the end of the season.
(2) The same points as in the primula and radish
experiments.
(3) The weight of the crop when tubers are grown.
MODEL EXPERIMENT IV.
" Top-Dressing."
The effect of humogen may be tried on any plants
or grass growing in the garden at any time from
March to September. Use 4 to 6 ounces to the
square yard, and work well into the soil. On grass
spread the humogen over the surface. For this
experiment humogen should be applied only in
plots. Thus, half a bed should be treated and the
other half not treated, so that improvements result-
ing may be noted. Apparently inconsistent results
must be expected in this experiment, as humogen
will not usually force a plant into fresh growth if the
normal resting stage has been reached for the season.
NOTE all such points as described in the primula
and radish experiments, and especially compare
the condition of the treated and the untreated plants.
NOTE TO FARMERS AND GARDENERS.
As a measure of prudence it would be wise for
farmers and gardeners wishing to experiment with
humogen on a large scale to write direct to Mr. Alfred
204
THE SPIRIT OF THE SOIL
Machen, 48, Frances Road, Windsor, describing
accurately the nature of the soil, what has been
recently grown in it, and the crops on which it is
proposed to use humogen. A report should be sent
in at once if negative results are obtained.
MODEL FORM FOR RECORDING RESULTS.
HUMOGEN EXPERIMENTS.
Date. .
Crops.
Quantity.
How applied.
Result : Weights
where possible.
General Remarks.
Name and Address of Experimenter.
NOTE. — Where possible, supply photographs. Address all
remarks to Mr. Alfred Machen, 48, Frances Road, Windsor.
APPENDIX A
NITROBACTERINE AND LEGUMINOUS PLANTS
IN connection with the use of nitrobacterine, in over
80 per cent, of the reports made to Professor Bottomley
there was evidence that the use of the material had
shown a distinct advantage gained by the crops
through inoculation. As a method similar to Professor
Bottomley's is still being employed in America, the
original American method having been abandoned, the
following reports, which were published by Country
Life in a pamphlet, Seed and Soil Inoculation for
Leguminous Crops, in 1908, may be of interest. It has
been found since that many of the failures were due
to preventable causes. The successes obtained, however,
remain of considerable historic and practical interest.
As in the original pamphlet, the reports are grouped
by counties.
CORNWALL.
MARAZION — Peas. — The peas were a great success.
Inoculation of soil and seed returned a good 30 per cent,
more than only seed inoculation, and the seed inoculation
showed a good 20 per cent, better crop than the farmyard
manured peas. Inoculation in both cases rendered a
fortnight earlier marketing possible over the manured.
205
2o6 THE SPIRIT OF THE SOIL
CHESHIRE.
CHESTER — Peas. — Taking a piece of poor ground in an
old garden we planted one portion with inoculated seed,
and in another portion inoculated the soil. Against this
and adjoining we sowed the same kind of peas untreated,
half upon ground treated with ordinary farmyard
manure, the other half with a little bone manure in
addition. As regards the result it was easily discernible
which peas had been treated, the foHage being stronger,
and the pods larger and more freely produced than
those grown on the manured ground.
CHILDER THORNTON — Clover. — They have just begun
cutting the oats, and are very pleased with the inoculated
clover; it is almost too good, very strong plants.
HALE — Sweet Peas. — The inoculation of my sweet peas
has been an immense success. Unfortunately the un-
favourable weather this summer prevented me showing
in London on July 16, but with blooms 2 J inches across,
and stems 18 inches long, in addition to numerous four
blooms per stem (very few less than three), I can say with
confidence that there were none better. Whilst in this
district and Manchester they have been generally
remarked upon. From the very commencement of
operations the inoculated seeds showed more vigour than
the others.
DORSET.
WEYMOUTH — Peas. — For experiment with peas I
sowed one-third without and two-thirds with culture
treatment to seeds previous to planting. Results as
follows :
1. Stages of early growth little difference.
2. As soon as flower blooms appeared the haulms of
" culture " gained considerably in strength, height, and
show of blossom.
APPENDIX A 207
3. Pods of " culture " fairly 20 per cent, better — both
in size and quantity.
4. Flavour decidedly superior to " non "-treated.
5. A few haulms of " culture " bore pods of far larger
size than the type.
DEVON.
TAVISTOCK — Clover. — The inoculated clover was taller
by 3 inches than the uninoculated.
DENBIGHSHIRE.
WREXHAM — Sweet Peas. — Inoculation has been quite
a success. The flowers are greater in number by at least
20 per cent, than those not treated, and the size of the
flowers is much larger.
ESSEX.
EPPING — Peas. — First sown peas, inoculated, a fine
crop with haulms of great thickness, and fruit large and
juicy. Second sowing, uninoculated, results very poor,
haulm thin and weakly, crop almost useless. The
ground on which first crop was sown had had no peas
on it for several years, whereas the ground on which
second crop was sown had had peas grown on it in the
previous year.
CHAPPEL — Sweet Peas. — The inoculating material you
sent me was a distinct success. The sweet peas started
to blossom earlier than the non-inoculated, and grew
2 feet higher. I gained three prizes with them in open
classes at local shows. My soil is very light and shallow,
and was never cultivated until two years ago, and num-
bers of people have been surprised at my display of
sweet peas on such poor ground.
WOODFORD — Peas. — Seeds treated; plants also
watered with solution at later period of growth. The
208 THE SPIRIT OF THE SOIL
treated peas show a very much more vigorous growth,
and much better yield of fruit.
HORNCHURCH — Peas. — The row which I treated with
your preparation seems generally stronger and certainly
earlier than the others. As regards earliness, the row
treated, although planted out a fortnight later, began to
flower before those not treated.
GLOUCESTERSHIRE.
STAUNTON — Vetches. — The inoculated were greener
and thicker than those not treated.
Broad Beans. — The inoculated were up a week and a
half before those not treated, and were very much
greener and more weight.
2 rows inoculated, 65 yards long, gave 4j pots.
2 „ not inoculated ,, „ ,, 3 „
a gain nearly half as much again, ij pots, or 52 pounds,
a pot being 42 pounds.
Peas. — The inoculated peas were a great success. They
were from the beginning very much greener than those
not dressed, and the pods were J to i inch longer, and
much larger peas. I had the best crop of peas round
here for 2 or 3 miles, and was the first to sell to the
greengrocers in Gloucester in quantities. From a
quarter of an acre planted with i bushel inoculated seed
I picked 33! pots (42 pounds to the pot), selling them
for £7 1 8s. gd. From a quarter of an acre planted with
i bushel non-inoculated seed, but dressed with i cwt.
superphosphate and J cwt. sulphate of potash, I picked
only 14 pots, selling them for £2 5s. 6d. I also planted
a quarter of an acre with i bushel inoculated seed, and
manured with J cwt. superphosphate and \ cwt. sulphate,
and picked 54^ pots.
APPENDIX A 209
This village is composed of about 80 small holdings
from 2 to 4 acres, and most of the people grow market
garden stuff. They were surprised at me being able to
pick so much off the small amount of ground. I shall
be pleased to obtain more inoculation material next year,
when I want to try it on some heavy clay land which is
very poor, and has been laid down two years.
GUERNSEY.
RAMEE — Runner Beans. — The beans were grown with
the material you were kind enough to send us, and we
may say that we have never had a better and earlier
crop. The seeds came up very strong, and the leaves
had a nice dark colour. We picked the first beans six
weeks after sowing.
A more detailed report states: On October 5, 1906,
we planted the house with beans, which did not crop very
well. The house is 200 feet long and 30 feet wide. This
crop was finished on February 21, 1907. We then
cleansed the house, burned some sulphur, washed the
glass, and trenched the ground about 18 inches deep,
and worked in 2 cwt. pulverized chalk, and ij cwt.
Cross's organic manure. We replanted the house with
inoculated seed on February 22, and our first beans were
sent to market on April 8. We can assure you beans
have never before done so well in our ground.
HANTS.
WINCHESTER — Peas. — The inoculated peas are grow-
ing and bearing well, especially as none of them were
manured. My opinion is that inoculation is a great
help on such poor soils as mine.
14
210 THE SPIRIT OF THE SOIL
JERSEY.
ST. OUEN'S — Lucerne. — The inoculated seed came up
better than the untreated, and the crop is now a lot
thicker and of more even growth.
Peas. — I found the culture increased the pea crop a
great deal, and they were at least a week earlier than
the non-inoculated. The land is very poor gravelly soil.
KENT.
FAVERSHAM — Clover. — Culture applied by being mixed
with earth, then spread and harrowed. Treated half acre
yielded 2j waggon loads of clover fodder; untreated,
2 loads. The clover on the treated part was stouter and
larger than on untreated. Soil rather thin near the chalk.
BECKENHAM — Sweet Peas. — I have not grown sweet
peas before this year, and therefore cannot compare with
any previous results. I may say, however, that my plants
have excited the admiration of my friends. I treated
the seeds with your culture, and some of the plants have
run up to 8 feet in height. The flower-stalks have been
in some cases 16 inches long, and while threes have been
general, there have been several fours, the blooms being
of fine size.
LYMINGE — Peas. — The peas greatly benefited by your
inoculating process. I had as many as 13 peas in a pod,
and the general run of the pods contained 8 or 9.
CANTERBURY — Beans. — Strip 20 furrows wide through
centre of field sown with seed not dressed yielded
ii bushels 5 gallons; strip 20 furrows wide (above) sown
with inoculated seed yielded 14 bushels i gallon ; similar
strip (below) yielded 14 bushels 7 gallons. The whole
of the field where seed was treated gave a yield of
6 quarters 2 bushels, which was very good indeed for such
APPENDIX A 211
poor land, and speaks very well indeed for the farms you
so kindly set to work on our account. Now that this
has been such a success, may I hope you will kindly
furnish me with some more bacteria for the coming year,
or tell me how I can obtain it.
LANCASHIRE.
GRAPPENHALL — Beans. — I had a bed inoculated and
one without. In early stages those inoculated seemed
the stronger plants, but at maturity there did not seem
much difference ; but I shelled them myself, and consider
those inoculated yielded fully 30 per cent, more than
those non-inoculated. I planted them in ground that
had no manure for two years, and I consider the results
very satisfactory.
WHALLEY RANGE — Peas. — The plot treated with cul-
ture was approximately a fortnight in advance of a
similar plot planted with untreated seed. The plants are
exceptionally good.
Sweet Peas. — Seeds which were treated did exception-
ally well, growing plants a third higher than similar
seeds untreated. Also on the plants which have been
treated with culture I notice an unusually large pro-
portion of flowers, with fours and occasionally fives on
one stem.
LEICESTERSHIRE.
DESFORD — Peas. — The crop is 20 per cent, better on
the untreated peas. The haulm is much more robust
and healthier in appearance also, and flowers are still
being produced, while the non-inoculated plot is over.
LINCOLNSHIRE.
WOODHALL SPA — Green Peas and Sweet Peas. — Inocu-
lated were most successful; uninoculated but a poor crop.
212 THE SPIRIT OF THE SOIL
Scarlet Runners promise a full crop, though growing in
very poor sandy soil — in fact, little more than sand.
They are certainly as prosperous, if not more so, than
the non-inoculated plants in manured soil.
MIDDLESEX.
WHITTON— Peas.— The results of treating the peas
with bacteria have been eminently satisfactory. My
experience was as follows :
" Gradus," without inoculation, a fair crop, but they
were soon over.
" Sutton's Ai," inoculated, heavy crop, with abun-
dance of well- filled pods.
" Veitch Perfection/' inoculated, a very heavy haulm
packed with pods, so much so that the weight of the crop
broke the haulm down, though they were " re-sticked."
" Exhibition," inoculated, showed a wonderful crop;
these were so prolific that the haulms broke down under
their weight of produce, growing 6 to 7 feet high, with
pods 6 and 7 inches long.
All the above were sown in new ground, having never
grown anything before except grass. I estimate the
produce from inoculation was from 30 to 40 per cent,
more than from the untreated seed. I was told that my
peas were the finest in the district.
HARROW — Runner Beans. — I tried your system of
inoculation upon some runner beans during the past
season, and was surprised at the results. The inoculated
beans yielded 45 to 50 per cent, more in weight than
those grown under ordinary conditions.
NORFOLK.
NORWICH — Peas. — The inoculated peas were three
weeks earlier for market, and decidedly 50 per cent, more
prolific than the non-inoculated.
FIG. 17
The number of blooms thrown and the size and colour of the individual
blooms are the main results obtained by the application of humogen
to the primula. The above photograph shows two specimens of
Primula Keivensis. Both were planted in ordinary potting compost,
but the one on the right was watered continually with humogen
extract, while the one on the left was watered with guano extract.
(Grown at the Royal Gardens, Kew.)
APPENDIX A 213
MARSH AM — Peas. — We made our experiments with
the greatest care, inoculating six rows of peas, planting
different sorts. In every case the yield from the inocu-
lated rows (we planted fifteen rows in all) is three times as
good as from the uninoculated, the pods hung in clusters,
and the yield was excellent, and earlier than we have
ever had before.
SWAFFHAM — Peas. — Result excellent. An exceed-
ingly heavy crop. Beyond this, the most noticeable
features about the different varieties are that the inocu-
lated have continued bearing much longer than usual, and
the almost complete freedom from maggots in the pods,
and from any appearance of mildew on the foliage.
NOTTS.
SOUTHWELL — Clover. — The clover seed was sown on
land which before had failed to produce a crop. The
treated seed has come up very thick, much better than
the untreated, and there is a fine crop.
SHROPSHIRE.
OSWESTRY — Vetches. — Where the vetches were dressed,
your dressing seems to have acted wonderfully, and a
fine crop has resulted.
Peas. — Our inoculation experiment has turned out a
complete success. We have had a splendid crop. The
inoculated crop overtook another crop, not inoculated,
by four weeks.
BRIDGNORTH — Peas. — The bacteria culture was very
successful. The seed peas were treated strictly accord-
ing to instructions, and I had a check lot of untreated
peas sown parallel (and 4 feet away) to the treated peas.
The haulm of the treated peas grew very large, and the
foliage was fine, and remained clean and healthy. The
214 THE SPIRIT OF THE SOIL
plants blossomed very freely, and very many pods were
produced. In the case of the untreated peas the pods
were few, and did not fill well, and the peas produced
were not as sweet as those on the treated peas. I gave
some of the culture to a friend, who was sceptical and
gave a grudging consent to its use. He has never before
been able to grow a good crop of peas in his garden.
This year he says: " The only things to do any good are
the peas," so you may rely on it that the culture has done
a lot of good.
STAFFORDSHIRE.
TAMWORTH AGRICULTURAL COLLEGE. — Clover sown
with rye-grass inoculation gave an increase of about
15 per cent. Tares inoculated showed an increase of
about 10 per cent.
SOMERSET.
BATH — Sweet Peas. — The inoculation with sweet peas
was quite successful, the inoculated seed producing the
best flowers that I have ever had, and much stronger
than the seed which was not inoculated. Inoculation
was by watering the planted seeds. My soil is loam, and
always kept well manured.
SURREY.
HINDHEAD — Sweet Peas. — The inoculation experiment
has been very satisfactory. We planted the inoculated
sweet peas in poor sandy soil which had not previously
borne flowers — dug-up bracken and heath land. The
flowers have been beautiful and plentiful, and at this
date, when the non-inoculated peas are over, the inocu-
lated are still plentiful and seem to have an unusually
sweet odour ,
SUTTON — Sweet Peas. — Some freshly dug meadow-land
was sown; one half the seeds were treated with the solu-
APPENDIX A 215
tion and the young plants watered as advised, the other
half untreated. The treated seeds produced the finest
show of flowers we have ever raised, but the young plants
from the undressed seeds were unfortunately so badly
attacked by slugs and snails as to make comparison
useless. Some of the solution was given to a gardener at
Carshalton. He divided his seed into two lots — treated
and untreated. His soil was a light loam on chalk. The
untreated seeds produced a good show of flowers, but
the treated seeds did far better. He estimates that the
yield of flowers was increased by about a third.
WOKING — Peas. — The " pea culture " is a great suc-
cess. Those peas watered with the solution have yielded
in an astonishing manner — the yield has been more than
double.
Peas. — I planted the inoculated peas on land that has
not been manured for many years, and had a crop of
peas quite equal to those grown by a friend on manured
soil.
Broad Beans. — I had similar results with broad beans,
which produced a later growth almost equal to the first.
REDHILL — Peas. — From i pint of peas inoculated the
yield was at the very least 35 to 40 per cent, more than
from the pint not treated. We are still gathering from
the inoculated peas, and several pods when opened show
8 and 9 peas in each.
Scarlet Runners. — The inoculated scarlet runners are
quite a sight, reaching the tops of the 8 and 9 feet sticks,
and I have had to run strings (like they do hops) to help
the runners. The blossoms are a wonderful sight, and
the lower ones are showing runners of 8 to 10 on one
stem.
KNAPP HILL — Beans. — I am pleased to say that inocu-
lation has been a splendid success. I treated half of
216 THE SPIRIT OF THE SOIL
each row of broad beans with the solution direct to the
roots. The photos I send you show the comparative
sizes of the bean pods at the time I commenced to pick
them. The inoculated ones were 7 J to 8 inches long ; the
non-inoculated only 4! inches long. I left four of the
best plants in both inoculated and non-inoculated plots
to grow to maturity. The average length of the pods
from the inoculated plants was n inches, averaging
8 beans to the pod; the non-inoculated 8J inches long,
with 6 beans. The inoculated beans were quite three
weeks earlier than the others.
Peas. — The peas were treated in the same way, and
inoculation was equally successful. The inoculated were
ready quite two weeks before the others. My garden is
old orchard land, and the ground received no manure
other than that from the grass which was trenched in
about June, 1906.
SUSSEX.
BATTLE — Clover. — I sprayed part of a field of grass,
cut over each year then pastured, with the culture
solution. Now the sprayed part shows a great deal
more white clover than the rest of the field. On a
piece of very poor land of 7-year-old pasture I sowed
inoculated white clover seed. The result has been a
great improvement in the clover compared with other
portion of the field, which had formerly the best
clover.
BRIGHTON — Peas. — We planted the inoculated peas in
the poorest ground we possess, and they have done
exceedingly well.
Sweet Peas. — We also sowed some inoculated sweet
peas on a cinder path at the top of a low wall, and they
have grown and blossomed very freely, and looked very
APPENDIX A 217
nice hanging over and covering the wall. Our friends
have been quite astonished to see them growing in
cinders.
WILTSHIRE.
CHIPPENHAM — Peas. — The experiments have much ex-
ceeded my expectations. I applied the culture at three
different periods — at planting seed, and twice during
growth, on a piece of remarkably poor land. They grew
half as high again as usual, strong haulm, of lovely deep
green, and simply smothered with blossom; peas large
and well- filled pods — double the usual crop.
Sweet Peas, treated in same manner as peas, have been
the admiration and envy of my neighbours, growing
from 8 to 9 feet high, and literally a feast of blossom,
with stems 12 inches and more in length; in bloom early
in June, and are still (August 26) making a brave show.
It is truly a wonderful discovery this microbe, and bids
fair to revolutionize ideas of gardening.
WORCESTERSHIRE.
EVESHAM — Peas. — I am sorry I am unable to give you
accurate comparative results on inoculated and un-
inoculated plots owing to reasons given below, but in
comparison with my neighbours I cropped, through your
assistance, the best return on my peas in the immediate
neighbourhood, and they were picked quite ten days
earlier than others who planted on the same day.
Though the land where they were grown is extremely
good " black soil," for some reason it will not grow peas,
and this is, I believe, the first time anyone has matured
a crop on it.
Lucerne. — I have grown, with the help of your bacteria,
a lucerne crop far above the average.
2i8 THE SPIRIT OF THE SOIL
YORKSHIRE.
BRADFORD — Sweet Peas. — The sweet pea rows which
I inoculated twice with your bacteria have been an eye-
opener to all the other sweet pea growers in this district.
The ground has had no manure for 3 years, but had a
good top-dressing of lime 2 years ago. The foliage,
bloom, and height of the plants are far superior to others
grown in same district which have been fed with arti-
ficials and farmyard manure.
Peas. — On culinary peas the result has been mar-
vellous. The haulm was very large and thick, and the
pods very large and of a lovely dark green colour.
SHEFFIELD — Runner Beans. — Inoculated and non-
inoculated rows were grown in soil which had had no
manure for 10 years. The produce from both lots was
carefully weighed, and showed an increase of inoculated
over non-inoculated of 43 per cent. Better beans were
not to be found in the neighbourhood.
Peas. — The peas were grown on clay soil. Equal
quantities of inoculated and non-inoculated peas were
sown, and yielded: Inoculated, 631 pods; non-inoculated,
433 pods — a gain of 45-7 per cent. The inoculated pods
were longer and fuller, and & fortnight earlier.
Sweet Peas. — The inoculated sweet peas bloomed
remarkably well, and were the best in the neighbourhood.
Nurserymen and market gardeners came from miles
round to see them. They carried off Firsts wherever
they were shown, and the proceeds from the sale of
flowers were abnormal.
SCOTLAND.
KELSO — Peas. — Three-quarters of a pound of inocu-
lated pea seed yielded more than i J pounds uninoculated ;
APPENDIX A 219
the inoculated peas had larger pods, were better filled, of
finer flavour, and more uniform in shape than the un-
inoculated. The inoculated peas gained the second
prize at the District Show.
MELSETTER — Clover. — I put the inoculation liquid on
about a quarter of an acre of grass and clover as a top-
dressing. In about a week I could see an improvement,
and it (the clover) was far higher and thicker than the
rest of the field right on until it was cut. There was
double the quantity on it, and it was the same with the
aftermath; it came up the second time far thicker and
stronger than the rest of the field.
WORMIT (FIFE)— Peas.— Of those that have already
come to maturity, I find that the pods from the inoculated
seed are more numerous and much better filled than the
pods from seed not treated, the ratio of produce being
about 2 to i.
Beans. — Of the beans I cannot yet speak with cer-
tainty, as the crop is so late this year, but the pods of the
treated portion appear to be filling up much better than
the rest.
ELGIN — Clover. — The inoculation experiment has been
a great success. I sowed the clover with oats. The part
I left untreated has been a failure, where treated there
is a good crop. I thought when I sowed it it would
have no effect on the corn crop, but only on the grass
next year, but I am glad to say that on the top of the
field which is inoculated, where the land is very poor
and no depth of soil, there is a good crop of oats where
it was never anything before. The neighbouring farmers
are wondering what I have done to it. On the part of
the field I left uninoculated the oats are not nearly so
high or so thick as where it is inoculated.
FORRES — Clover. — I am glad to say that the crop of
220 THE SPIRIT OF THE SOIL
inoculated clover is the best we have ever had, quite
double, if not more, than usual, and it has grown where
in one part clover never would grow before. I must
congratulate you on your success, and trust I may be
allowed to have some more inoculating material next year.
RUTHERGLEN — Beans. — On April 17, 1907, I took
i pound 10 ounces of Bunyards' Exhibition Long Pod
Beans, of which I planted i pound 6 ounces after inocu-
lating as directed, the other 4 ounces were planted un-
inoculated at the same time. The former, when from
3 to 4 inches above ground, were again inoculated with
the dilute solution, the latter were not. The garden
slopes to the north pretty steeply, and the soil is heavy
clay, which a month before planting had dug into it
farmyard manure in about the proportion of 14 cart-
loads per acre. Yesterday (October 9) I took 20 stalks
as they came from an inoculated and a non-inoculated
row, and found the weight of all the pods of each were
7 J pounds and i pound 9 ounces respectively, and of the
beans alone 2f pounds and £ pound. The sta]ks from
inoculated seed are quite remarkable for their vigorous
growth both in weight and length, and if attention had
been given to pruning of side-shoots the harvest of pods
would in the end, I feel quite sure, have been appreciably
heavier, although even as it is it is quite remarkable.
The stalks are still green with a considerable show of
blossom, although at this late season they must soon
shrivel and die down.
IRELAND.
THURLES — Clover. — The inoculation experiment is a
great success. All the clover is growing wonderfully
thick through the barley, though it is said locally that
clover will not grow in this townsland.
APPENDIX A 221
KING'S COUNTY. — Peas. — Inoculated rows have borne
most excellent crops, much better than in former years.
Beans. — A very marked difference was shown in growth
of the broad beans — those which I had not inoculated
being much smaller and fewer.
During the year reports have come to hand of various
experiments in different parts of the country, with inocu-
lating material obtained from abroad. In many cases
excellent results have been obtained, as indicated by the
three following reports :
ENGLAND.
ROTHAMSTED — Clover. — Land which was known to
have carried no leguminous crop for the last 50 years
was planted with red clover seed, and yielded as follows :
Plot A. Inoculated with Hiltner's preparation from Cwts.
Germany . . . . . . . . . . 76*4
Plot B. Inoculated with Moore's preparation from
America . . . . . . . . . . 72-9
Plot C. Uninoculated .. .. .. 61-9
SCOTLAND.
WEST OF SCOTLAND AGRICULTURAL COLLEGE — Beans.
— Professor Wright reports: " On all the farms (five) on
which the inoculation proved beneficial the increase of
crop obtained was enough to give a very satisfactory
return for the labour and cost. An average increase of
304 pounds grain per acre, as compared with 3 \ cwts. of
straw, shows clearly that the inoculation, while it gave a
larger crop of straw, increased the yield of beans in a
much greater degree, and hence the effect of this ad-
ditional treatment has been to enhance still further the
222 THE SPIRIT OF THE SOIL
grain-producing character of the bean crop. The average
return, amounting to about 4 Jbushels beans and 3 Jcwts.
bean straw per acre, would have formed a sufficient
return for a much higher expenditure.
" But, apart from one failure, and making due allow-
ance for the discrepancies inseparable from field experi-
ments, the results on the whole tend to show that, under
suitable conditions and on ordinary bean soils, the
practice of inoculation appears likely to be beneficial
and profitable."
Lucerne. — At the College Experiment Station, Kil-
marnock, experiments on the inoculation of a growing
crop of lucerne have been in progress during the past
three years. A growing crop of lucerne was subdivided
into three plots. All received equal dressings of super-
phosphate and potash; but as regards nitrogen, A had
no nitrogenous manure, B was dressed with nitrate of
soda at the rate of 2 cwts. per acre, C was inoculated with
culture material from Germany. Last year the green
produce from each plot was carefully weighed, and gave —
Tons. Cwts. Qrs.
A. No Nitrogen . . . . . . 7 o 3 per acre.
B. Two cwt. Nitrate Soda . . 9 8 2
C. Inoculated .. .. ..12 5 p ,,
IRELAND.
Vetches. — The inoculated seed produced 23 tons of
vetches (cut green) per acre, while the uninoculated pro-
duced only ii tons 7 cwts.; showing an increase of
ii tons 13 cwts., or more than double, in favour of
inoculation.
APPENDIX B
EFFECTS OF TREATING PLANTS WITH
HUMOGEN
THE following are among the reports that have been
received from growers as to the effect of using bacterized
peat. The first groups of results are those obtained by
Mr. Machen (who is now assisting Professor Bottomley)
from experimental plots at Eton Experimental Gardens
in 1913 and 1914. In some instances it has been possible
to tabulate the results. As further reports are received
from growers they will be added to this appendix in
subsequent editions.
ETON EXPERIMENTAL GARDENS (1913-1914).
(Report by Mr. Machen. The first report was quoted by Pro-
fessor Bottomley in the lecture he delivered before the
Royal Society of Arts in 1914.)
The whole plot was 51 feet long by 36 feet wide. The
plot was divided across its breadth into three equal
portions of 15 feet each, and a smaller portion of 6 feet.
This gave three plots of 60 square yards each, and a
small plot of 24 square yards. These plots were treated
as follows: Plot i, complete artificial manure (top-dress-
ing), 4 ounces per square yard; Plot 2 (small plot), no
manure; Plot 3, bacterized peat (top-dressing), 9 ounces
per square yard ; Plot 4, one ton farmyard manure (half
dug in subsoil and half in top spit).
223
224
THE SPIRIT OF THE SOIL
The rows of plants ran across each of these four plots.
As each crop matured careful weights were taken, and
are shown in the table on p. 225.
The percentage increase of the produce from the peat-
treated plots over those with no manure, artificials, and
farm dung is as follows :
No Manure.
Artificials.
Farm Dung.
Per Cent.
Per Cent.
Per Cent.
Potatoes
123
75
41
Turnips
IOO
47
25
Beet. .
281
54
43
Onions
no
no
46
Carrots
260
20
28
It will be noticed that in all cases the yields are small.
This is accounted for by Mr. Machen in the following
notes :
1. Sandy soil over gravel. No manure for nine years,
and had been continuously cropped with potatoes,
followed by brassica.
2. The previous season (1912) crops were a complete
failure. Land as nearly exhausted as possible.
3. The mixture of artificials used usually gives better
results than dung, but owing to the exceptionally dry
spring of 1913 the wet farmyard manure had an
advantage.
4. All the crops were much below the normal owing to
— (a) starved land ; (b) exceptionally dry season on a
hot, dry soil. Potatoes were all first earlies.
5. The land was specially selected for testing food
values on an exhausted soil.
In 1914 experiments were carried out on similar lines,
giving the results tabulated on p. 227. A striking feature
APPENDIX B
225
s
Q
«•§
,0 O
£ O
O
00
if
P3
00 +?
; - <D
'S3"
o
vO co
. N
co O
•° *v-,
o
0 co
O - 0)
" SP
«
!
i
co O
£ ^
«
CO °
rQ VO
42-53 «
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I
H
.2
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15
226 THE SPIRIT OF THE SOIL
of them was the residual effect of peat on the plots that
had been treated in the previous year. As regards these
plots, the last in the table, no fresh humogen, artificials or
manure were applied.
MID-SURREY GOLF COURSE.
The remarkable results obtained on the Mid- Surrey
Golf Course are described as follows by the Editor of the
Garden, writing in Country Life on November i, after
inspecting the greens in the company of Mr. Lees, the
groundsman at Mid-Surrey: " The first to be dressed
was a practice green, which, owing to the very hard wear
to which it is subjected, and the fact that it is on sand,
always gives a great deal of trouble, particularly in the
autumn. This green was treated on August 28, and at
that time was in a very worn condition. Now (Novem-
ber i) it is as perfect as a green could be, the turf being
very close and hard, and of a particularly healthy colour^
Near to this practice green, and also on sand, is an
undulating green that Lees assured me has always been
a worry to him at this season. This, when dressed with
the prepared peat a little more than a fortnight ago,
was very brown in places, but now the brown patches
have almost disappeared, and the turf is very healthy,
and of excellent substance. A third green, also of an
undulating character, was treated on Tuesday of last
week, and three days later was showing signs of improve-
ment. After experimenting with different quantities to
ascertain the proper amount to use — 2, 4, 6, 10, and
12 ounces per square yard respectively — Lees has come
to the conclusion that 3 ounces per square yard produces
the most satisfactory results. This is applied in a pul-
verized state as a top-dressing, and for the first few days
APPENDIX B
227
*°z
L
£§-
• a
II*
0 -oT
5*gSg>
^ w>2
ill!
11
5
<o 2
1^
£
a
S^
228
THE SPIRIT OF THE SOIL
seems to open up the soil and to let the grass through,
after which this slight sponginess disappears. Not only
have these dressings had a most remarkable effect on the
blades of the grasses, but root growth has also been
increased to a very considerable extent."
TABULATED RESULTS.
ADDLESTONE.
DATE, JUNE 27, 1915.
Crop.
Quantity.
How applied.
Result: Weights
when possible.
Tomatoes
I-IO
Mixed in soil
Tomatoes treated when
put into 48 pots took
the lead of the others.
Very pronounced with-
in a week, and still
retain their extra
vigour, etc.
THOMAS STEVENSON, Woburn Place Gardens, Addlestone.
BIRMINGHAM.
DATE, JULY 17, 1915.
Auricula
Mixed in soil
I find that auriculas
potted with humogen
are quite free from
woolly aphis, and those
not so potted are still
showing same.
A friend I gave some to
finds the growth bet-
ter, and confirms what
I say with regard to
aphis.
T. E. ASTON, 25, Grosvenor Road, Handsworth, Birmingham.
APPENDIX B
229
ILFORD.
DATE, OCTOBER 17, 1914.
Crop.
Quantity.
How applied.
Result : Weights
when possible.
Flowers in
Periodical
I had a hanging-basket
hanging.
top-dressing
containing geraniums
basket
and asparagus ferns,
to which I have ap-
plied periodically a
dressing, with most
remarkable results.
Under ordinary cir-
cumstances I should
have been obliged to
replenish the basket
with later flowering
plants at least once.
but under humogen
we have had a succes-
sive crop of new spikes
and buds, with the re-
sult that the plants,
which were put in last
May, are still flower-
ing, October 17, 1914.
J. B. P. HARRISON, Ilford.
KEW.
DATE, 1913.
Pot plants,
in variety
1-9
Mixed in soil
The plants, beyond or-
dinary details, had no
special attention dur-
ing growth other than
that devoted to start-
ing them; after a fort-
night or so they were
left to themselves.
The results in some
cases were extraordin-
ary, and not compar-
able with those ob-
tained from ordinary
nitrogenous manures,
the root development
being very marked.
MR. COUTTS, the Royal Gardens, Kew : Journal of Royal
Society of Arts, March 13, 1914.
230
THE SPIRIT OF THE SOIL
SLOUGH.
DATE, JULY, 1913.
Crop.
Quantity.
How applied.
Result: Weights
when possible.
Tomato
A. Watered
,
A. Equal to D.
with bac-
teria once
B. Rough
—
B. 25 per cent, superior
humogen
to A and D.
placed on
crocks
C. i-io
Mixed with
C. Equal to B.
soil
D. Control
1-4 old rot-
D. Equal to A, inferior
ted dung.
to B and C.
Fed with
Chelsea
Horticul-
tural Ferti-
lizer every
three days J
General Remarks. — Tomato plants hi pots gave better results
with far less trouble than, any other known method of feeding, at
a minimum of expense. — J. ALLGROVE, Langley, Slough.
SLOUGH — Continued.
DATE, JULY, 1914.
Garden
peas
Water
tract
4 gallons to
60 yards
The plants responded
to its application
quickly, the growth
was much stronger,
and continued after
untreated plants were
quite yellow. The
pods were much finer
and more abundant.
General Remarks. — Three rows, each 20 yards, untreated;
weight of dry seed, 18 Ibs. Three rows each 20 yards, treated;
weight of dry seed, 28 Ibs. Percentage increase, 55-5 per cent.
Increased value, i8s. 3d. — JOHN ALLGROVE, Langley, Slough.
APPENDIX B
231
WINDSOR.
DATE, JUNE, 1915.
Crop.
Quantity.
How applied.
Result : Weights
when possible.
I. Pteris
I-IO
Mixed in soil
I repotted a few Pteris
Major
Major on August 20 in
humogen mixture. I
think the growth is
wonderful. They are
already (October 27)
much finer plants than
I usually get in six
months.
, From the small amount
I had I think the re-
sult is wonderful.
During my thirty
2. Maiden-
I-IO
Mixed in soil
years' experience I
have never come
3. Aspara-
across anything to
show such quick re-
gus
a. Sprengeri
I-IO
Mixed in soil
J suits. Twenty-six days
I after potting, maiden-
b. Plumosa
I-IO
Mixed in soil
hair have made nice
plants, while those
without are just mak-
ing a start.
The growths of aspara-
gus are much stronger
and a much better
colour.
F. DAVIS, Nurseryman, St. Leonard's Road, Windsor.
WINDSOR— Continued.
DATE, AUGUST 4, 1915.
Begonia
I-IO
Mixed in soil
Extraordinary profu-
sion of bloom. Over
100 blooms on a semi-
double variety, quite
twice the amount of
growth and bloom
over untreated. Very
free and vigorous, with
healthy green leaves.
232
THE SPIRIT OF THE SOIL
WINDSOR— Continued.
Crop.
Quantity.
How applied.
Result : Weights
when possible.
Celery
Never had such splen-
did plants, now aver-
aging 30 inches high,
deep rich green foli-
age, and perfectly free
from fly. (Aug., 1915.)
Kale
4 ozs. per sq.
Mixed in soil
Grown in ash-heap, soil
yd.
more than half ashes
and broken pots.
" Growing wonderfully
strong."
Onions
6 ozs. per sq.
yd.
Mixed in soil
Crop promises to be
half as heavy again as
untreated.
Carnation
I-IO
Mixed in soil
Growth was both vigor-
ous and free, without
being soft. The quan-
tity of growth and
flower was remarkable.
Carnation
—
Plant in border col-
eel-worm
lapsed through eel-
worm. The soil where
plant was growing re-
ceived 3 ozs. of humo-
gen stirred in, and
*
new plant from pot,
planted in early May.
Now (August 4) the
plant is perfectly
healthy, and without
a trace of eel- worm.
Runner
4 ozs. per yd.
Mixed in soil
More vigorous growth,
Beans
run
thicker stems, and
heavier crop. Better
quality produce; full
of vitality, deeper
green foliage, and
much larger leaves.
Beans earlier i week.
Average length, 12 in.
Untreated, 9 in.
40 plants averaged £
bushel, gathered i|
bushels per week.
Every bloom set, result-
ing in large clusters.
APPENDIX B
WINDSOR— Continued.
233
Crop.
Quantity.
How applied.
Result : Weights
when possible.
Asters
1-20 ?
Mixed in soil
When pricked out into
boxes, plants grew at
tremendous rate and
produced very much
stronger plants. The
blooms were ready
thirteen days earlier
on stems averaging
15 in. as against 10 in.
on untreated.
The colour of the foliage
was a rich blue green,
and plants were very
stiff and sturdy.
Stocks
1-20 ?
—
As asters. Fourteen
days earlier, heavier
flowers, and very fine
plants.
Roses
4 ozs. per
Lightly
Growth both stronger
plant
forked in
and freer, the breaks
being very numer-
ous. The colour of
both foliage and
blooms greatly intensi-
fied, particularly with
Dean Hole and Lyons.
Treated and untreated,
growing side by side,
almost appeared dis-
tinct varieties.
Won 3 firsts, I third, I
cup — 5 entries.
G. W. BISHOP AND SONS, Windsor.
Tomatoes
i— 20
Mixed in soil
Plants grew away
quickly, making small
dark green foliage, and
setting fruit freely.
Treated plants are
better 25 per cent.,
both in quantity t and
quality of fruit. \
Fruits were ripej at
least three weeks
earlier than untreated.
234 THE SPIRIT OF THE SOIL
WINDSOR— Continued.
Crop.
Quantity.
How applied.
Result: Weights
when possible.
Garden
3 ozs. per yd.
Top-dressed,
Treated rows much
peas
run
hoed in
stronger in haulm, a
better colour, and with
a heavier crop of well-
filled pods.
Sweet peas
3 ozs. per yd.
Lightly dug
Taller, stronger, and
run
in
greener ; flower-stems
averaged 3 in. longer
than untreated. Colour
of flower intensified.
Continued growing
longer.
Coffee - col-
Watered in
When growth for sea-
oured liquid
son had apparently
finished and plants
were yellow, a water-
ing of strong liquid
produced new growth,
which a fortnight later
gave good blooms for
sale.
F, DAVIS, Nurseryman, Windsor.
Sweet peas
A small quan
tity sprinkled
There was a distinct
amongst pla
nts and hoed
gain in height ; vigour
in
of stem and foliage
very marked, and
colour and veining in
flowers distinctly im-
proved.
Won Bide Cup and
silver-gilt medal at
National Sweet Pea
Show, 1915, besides
securing 5 firsts, 2
seconds, i fifth,
N.S.P.S.— 8 entries, 8
prizes.
G. W. BISHOP AND SONS, Windsor.
APPENDIX B 235
OTHER RESULTS OF WHICH LESS EXACT
DETAILS ARE AVAILABLE.
BUCKS.
WINDSOR. — The Potatoes treated with the bacterial
culture gave an increase of 35 per cent, over the
untreated ; and the Lettuce were practically 100 per cent,
better.
ESSEX.
RAYLEIGH — Onions. — Inoculated, 8 pounds 3 ounces;
uninoculated, 5 pounds, 14 ounces. Increase, 39 per
cent.
GUERNSEY.
Tomatoes. — Inoculated 144 plants, gave yield of
8*06 pounds per plot; uninoculated 1,340 plants, gave
yield of 7-02 pounds per plot. Increase, 14-8 per cent.
KENT.
CATFORD. — The Rose-trees watered with the bacterial
culture yielded quite twice as many blooms as the
untreated trees.
W. RAMSGATE. — Tomatoes — where treated the foliage
was a darker green, and produced an enormous crop,
double that of the plants not treated.
MIDDLESEX.
GREENFORD GREEN (AUGUST, 1915) — Tomatoes. —
Two shallow boxes were taken. To one 56 pounds of
dung were added, to the other 2 pounds of humogen.
Three plants were grown in the first and four in the
second. Both sets of plants are far superior to others
236 THE SPIRIT OF THE SOIL
grown in the same house without fertilizers. There is
not much to choose between the humogen-treated and
the dung-treated plants in size, but those treated with
humogen are yielding ripe tomatoes, while those treated
with dung are only beginning to ripen. The fruits on the
humogen-treated plants are generally in a more advanced
stage.
" Having had such extraordinary results during the
past season by the use of humogen, I thought perhaps
the following particulars might be of interest to you :
" Sweet Peas. — I purchased the seeds from reliable
seedsmen, potted them last October, and planted the
seedlings out the second week in April as follows: On
the more favourably situated side of the garden I
planted eight seedlings to form clumps of 2 feet diameter.
I treated the ground in January with a well-known sweet
pea manure, and when the plants began to show bud I
watered them with liquid manure made from half cupful
of sweet pea manure and ij gallons of water. On the
other side of the garden I planted eight seedlings as
before, but treated the ground this time with humogen,
something like i in 10. When these plants began to show
bud I watered them with liquid manure made from one
cupful of humogen to i J gallons of water. This I gave
in each case once a week. Both clumps are still in
flower, and approximate heights are : Sweet pea manure,
8 feet 6 inches ; humogen plants, 10 feet. I have had
considerably more blooms, larger size, and longer and
stronger stems on the ones treated with humogen than
those treated with sweet pea manure. The neighbours
around are astonished at them, and no wonder. I have
never had such plants before.
" Dahlias. — These were treated with humogen, with
APPENDIX B 237
the result that I have magnificent blooms as regards
quantity, size, and shape.
" Roses. — These along with dahlias have been special
favourites of mine for some years past. For the last
three years I have had some good blooms, but nothing
like I have had this year. The only way I can account
for it is the use of humogen. To sum up, I have been a
keen amateur gardener for many years, and have tried
many fertilizers, but up to the present I have struck
nothing like humogen.
/'T. ATKINSON.
"CARNWATH,
"CHATSWORTH AVENUE,
"WEMBLEY HILL,
"August 4, 1915."
HARROW — Onions. — Treated rows, 41 pounds; un-
treated rows, 29 pounds. Increase, 41 per cent.
RUTLAND.
OAKHAM — Mangolds. — Two rows, 9 yards long.
Treated, 7 stones 10 pounds; untreated, 5 stones
2 pounds. Increase, 50 per cent,
Strawberries in pots and out of doors both showed an
improvement.
Sweet Peas more still.
Peas and Beans. — These showed a more vigorous
growth.
Early Potatoes gave a heavier crop and much brighter
sample than those treated with manure only.
Celery were more free from fly, and had a better
growth.
238 THE SPIRIT OF THE SOIL
SURREY.
" In a plot of ground used as a vegetable garden I had
obtained, up to this year, very poor results. This year
I determined to use humogen; the results have been
quite remarkable. The largest of last year's turnips only
reached the size of a fairly large strawberry; this year
I have had turnips the size of one's fist, and the smallest
are larger than the largest of last year's crops. I am
having very much better results with tomatoes, beans,
and lettuce, and I can without hesitation state that it
can only be due to the feeding properties of humogen.
'GEORGE F. WEST.
"4, HILBURY ROAD,
" BALHAM,
"August 4, 1915."
LIST OF PAPERS
BY PROFESSOR WILLIAM BEECROFT BOTTOMLEY,
M.A.
DEALING WITH BACTERIAL FIXATION OF NITROGEN AND THE
EFFECT OF SOLUBLE HUMATES IN THE SOIL.
" The Assimilation of Nitrogen by Certain Nitrogen-Fixing Bac-
teria in the Soil." (Proc. Roy. Soc. B., vol. Ixxxii., 1910.)
" Some Effects of Bacterio toxins on the Germination and Growth
of Plants." (Report Brit. Association, 1911.)
" The Fixation of Nitrogen by Free-living Soil Bacteria." (Re-
port Brit. Association, 1911.)
" Some Conditions influencing Nitrogen Fixation by Aerobic
Organisms." (Proc. Roy. Soc. B., vol. Ixxxvi., 1912.)
" Some Effects of Humates on Plant Growth." (Report Brit.
Association, 1912.)
" Ammonium Humate as a Source of Nitrogen for Plants." (Re-
port Brit. Association, 1913.)
" The Effect of Soluble Humates on Nitrogen Fixation and Plant
Growth." (Report Brit. Association, 1913.)
" The Bacterial Treatment of Peat." (Jour. Roy. Soc. Arts,
vol. Ixii., 1914.)
" Some Accessory Factors in Plant Growth and Nutrition."
(Proc. Roy. Soc. B., vol. Ixxxviii., 1914.)
" The Significance of Certain Food Substances for Plant Growth."
(Annals of Botany, vol. xxviii., 1914.)
" The Formation of Humic Bodies from Organic Substances."
(Biochem. Jour., vol. ix., 1915.)
"A Bacterial Test for Plant-Food Accessories (Auximones)."
(Proc. Roy. Soc. B., vol. Ixxxix., 1915.)
239
INDEX
ACCESSORY food bodies, 94,
96 sqq. See also Vitamines
and Auximones
Acid soils, 171 $<?<?.
America and inoculation, 53
sqq.
and nitrobacterine, 136,
137
Amides, 133
Ammonia from manure, 27
Annus mirabilis, 19
Antiseptics and soil organisms,
3°» 49
Auximones, 94, 96 sqq., 158,
191
and animals, 117
derivation of, 112
test for, 113 sqq.
Azotobacter, 28, 88, 89, 112
sqq., 139, 152
Bacillus radicicola, 60 sqq., Si,
82, 88, 139, 152
Bacteria in the soil, numbers
of, 25. See also Nitrogen-
fixing organisms, Nitrifying
organisms, Azotobacter, Ba-
cillus radicicola, Humogen,
Humus, etc.
Bacterized peat. See Humo-
gen
Beriberi, 99 sqq. See also De-
ficiency diseases
Beyerinck, 89
Board of Agriculture, 54 sqq.
Carbohydrates, 133
Carbon as plant food, 5
dioxide from manure, 27
Cavendish and nitric acid, 6
Chelsea Physic Gardens, ex-
periments, 1 02
Condensation, 129, 130
Clostridium pasteurianum, 89
Coal consumption in Eng-
land, 3
Cooke, 1 60
Coutts on Kew experiments,
141
Crookes on the nitrate prob-
lem, 5
Dachnowski on peat, 31 sqq.
Deficiency diseases, 99 sqq. See
also Beriberi, Scurvy, Vita-
mines, etc.
Dehydration, 128 sqq.
Detmer and humus, 80
England and the food-supply,
ii sqq.
Eykman and beriberi, 99
Fats, 133
Fielding and England's food-
supply, 12 sqq.
Food-supply in Europe, n sqq.
Funk, 99 sqq.
Hellriegel, 50 sqq.
Holmes, experiments by, 144
sqq., 153, 163
Hopkins, in sqq.
Humic acid, 69 sqq.
colloidal properties
of, 92
substances. See Humus
Humogen and its results, 81
sqq., 179 sqq., 225 sqq.
application of, 169 sqq.
cautions for use of, 197
sqq.
model experiments with,
200 sqq.
preparation of, 150 sqq.
prizes gained with, 184,
194. 195
testing of, 135 sqq.
241
242 INDEX
Humus, 64 sqq.
Hydra tion, 128 sqq.
Inoculation, results of, 53 sqq.
See also Humogen, etc.
Keeble, 158
Kew results, 102, 140 sqq., 178
sqq. See also Humogen,
Newspaper criticisms, etc.
Lawes, influence on agricul-
ture, 48
Lees, 226
Leguminous plants and nitro-
gen, 48 sqq. See also Nitro-
bacterine, Nitrogen-fixation,
etc.
Liebig, influence on Agricul-
ture, 47 sqq.
Lipman, 89
Machen, 93, 95, 225, 227
Malthus and the food-supply, 4
Manure and auximones, 116
decomposition of, 26
Moore, 101 sqq.
Mess culture experiments, 146,
163
Newspaper criticisms, 159 sqq.
Nitragin, 53 sqq.
Nitrate deposits, 4
problem, I sqq.
Nitrobacterine, 56 sqq.
and America, 137, 156
difficulties with, 137 sqq.
results with, 205 sqq.
Nitrogen as plant food, 5
balance-sheet, 7
fixation, 46 sqq., 88
-fixing organisms, effects
of, on soil, 92
and symbiosis, 90
Noble and inoculation, 53 sqq.
Oxidation, 128 sqq.
Pasteur and bacteria, 49
Peat, 31 sqq.
Peat, a < omplete plant food, 140
bac erization of, 87 sqq.
comj irison with other
manures, 86
decomposition of, 83 sqq.
extract, 85
uses of, 40 sqq.
Phosphates and humogen, 92
and manure, 28
Phosphotungstic fraction. See
Auximones
Plant inoculation. See Inocu-
lation
Potash and humogen, 92
and manure, 28
Prazmowski and inoculation, 53
Proteids, 133
Protozoa, 29
Reduction, 128 sqq.
Rice. See Deficiency diseases
Root-nodules. See Legumin-
ous plants
Rosenheim, 102 sqq., 158
Rothamsted, 48 sqq.
Schloesing and Miintz, experi-
ments, 49
Scurvy, 101 sqq.
Silver fraction. See Auxi-
mones
Standard bread, 102 sqq., 118
Starling and chemistry of the
blood, 98
Sterilization of soil, 153
Symbiosis and nitrogen-fixing
bacteria, 90. See also
Leguminous plants
Van Bemmelen and humus, 80
Vitamines, 94, 96 sqq.
Voelcker on peat, 44
Vordermann and beriberi, 99
Ward and nodule formation, 52
Watson- Wemyss, 100 sqq.
Weathers, experiments, 148,
149
Wheat. See Food-supply ^
Winogradsky, 89
BILLING AND SONS, LTD., PRINTERS, GUILDFORD, ENGLAND
THIS BOOK IS DUE ON THE LAST DATE
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