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Title: An Agricultural Testament (1943)
Author: Sir Albert Howard
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Title: An Agricultural Testament (1943)
Author: Sir Albert Howard
SIR ALBERT HOWARD, C.I.E., M.A.
Formerly Director of the Institute of Plant Industry Indore,
and Agricultural Adviser to States in Central India and Rajputana
TO
GABRIELLE
WHO IS NO MORE
The Earth, that's Nature's Mother, is her tomb;
What is her burying grave, that is her womb.
Romeo and Juliet.
And Nature, the old nurse, took
The child upon her knee,
Saying: 'Here is a story-book
Thy Father has written for thee.'
'Come, wander with me,' she said,
'Into regions yet untrod;
And read what is still unread
In the manuscripts of God.'
LONGFELLOW
The Fiftieth Birthday of Agassiz.
PREFACE
Since the Industrial Revolution the processes of growth have been
speeded up to produce the food and raw materials needed by the
population and the factory. Nothing effective has been done to replace
the loss of fertility involved in this vast increase in crop and animal
production. The consequences have been disastrous. Agriculture has
become unbalanced: the land is in revolt: diseases of all kinds are on
the increase: in many parts of the world Nature is removing the worn-out
soil by means of erosion.
The purpose of this book is to draw attention to the destruction of the
earth's capital--the soil; to indicate some of the consequences of this;
and to suggest methods by which the lost fertility can be restored and
maintained. This ambitious project is founded on the work and experience
of forty years, mainly devoted to agricultural research in the West
Indies, India, and Great Britain. It is the continuation of an earlier
book--The Waste Products of Agriculture, published in 1931--in which the
Indore method for maintaining soil fertility by the manufacture of humus
from vegetable and animal wastes was described.
During the last nine years the Indore Process has been taken up at many
centres all over the world. Much additional information on the role of
humus in agriculture has been obtained. I have also had the leisure to
bring under review the existing systems of farming as well as the
organization and purpose of agricultural research. Some attention has
also been paid to the bio-dynamic methods of agriculture in Holland and
in Great Britain, but I remain unconvinced that the disciples of Rudolph
Steiner can offer any real explanation of natural laws or have yet
provided any practical examples which demonstrate the value of their
theories.
The general results of all this are set out in this my Agricultural
Testament. No attempt has been made to disguise the conclusions reached
or to express them in the language of diplomacy. On the contrary, they
have been stated with the utmost frankness. It is hoped that they will be
discussed with the same freedom and that they will open up new lines of
thought and eventually lead to effective action.
It would not have been possible to have written this book without the
help and encouragement of a former colleague in India, Mr. George Clarke,
C.I.E., who held the post of Director of Agriculture in the United
Provinces for ten years (1921-31). He very generously placed at my
disposal his private notes on the agriculture of the Provinces covering a
period of over twenty years, and has discussed with me during the last
three years practically everything in this book. He read many of the
Chapters when they were first drafted, and made a number of suggestions
which have been incorporated in the text.
Many who are engaged in practical agriculture all over the world and who
have adopted the Indore Process have contributed to this book. In a few
cases mention of this assistance has been made in the text. It is
impossible to refer to all the correspondents who have furnished progress
reports and have so freely reported their results. These provided an
invaluable collection of facts and observations which has amply confirmed
my own experience.
Great stress has been laid on a hitherto undiscovered factor in
nutrition--the mycorrhizal association--the living fungous bridge between
humus in the soil and the sap of plants. The existence of such a
symbiosis was first suggested to me on reading an account of the
remarkable results with conifers, obtained by Dr. M. C. Rayner at Wareham
in Dorset in connexion with the operations of the Forestry Commission. If
mycorrhiza occurs generally in the plantation industries and also in our
crops, an explanation of such things as the development of quality,
disease resistance, and the running out of the variety, as well as the
slow deterioration of the soil which follows the use of artificial
manures, would be provided. I accordingly took steps to collect a wide
range of specimens likely to contain mycorrhiza, extending over the whole
of tropical and temperate agriculture. I am indebted to Dr. Rayner and to
Dr. Ida Levisohn for the detailed examination of this material. They have
furnished me with many valuable and suggestive technical reports. For the
interpretation of these laboratory results, as set out in the following
pages, I am myself solely responsible.
I am indebted to a number of Societies for permission to reproduce
information and illustrations which have already been published. Two
other organizations have allowed me to incorporate results which might
well have been regarded as confidential. The Royal Society of London has
permitted me to reprint, in the Chapter on Soil Aeration, a precis of an
illustrated paper which appeared in their Proceedings. The Royal Society
of Arts has provided the blocks for the section on sisal waste. The Royal
Sanitary Institute has agreed to the reproduction in full of a paper read
at the Health Congress, held at Portsmouth in July 1938. The British
Medical Journal has placed at my disposal the information contained in an
article by Dr. Lionel J. Picton, O.B.E. The publishers of Dr. Waksman's
monograph on Humus have allowed me to reprint two long extracts relating
to the properties of humus. Messrs. Arthur Guinness, Sons & Co., Limited,
have agreed to the publication of the details of the composting of town
wastes in their hop garden at Bodiam. Messrs. Walter Duncan & Co. have
allowed the Manager of the Gandrapara Tea Garden to contribute an
illustrated article on the composting of wastes on this fine estate.
Captain J. M. Moubray has sent me a very interesting summary of the work
he is doing at Chipoli in Southern Rhodesia, which is given in Appendix
B.
In making the Indore Process widely known, a number of journals have
rendered yeoman service. In Great Britain The Times and the Journal of
the Royal Society of Arts have published a regular series of letters and
articles. In South Africa the Farmer's Weekly has from the beginning
urged the agricultural community to increase the humus content of the
soil. In Latin America the planters owe much to the Revista del Instituto
de Defensa del Cafe de Costa Rica.
Certain of the largest tea companies in London, Messrs. James Finlay &
Co., Walter Duncan & Co., the Ceylon Tea Plantations Company, Messrs.
Octavius Steel & Co., and others, most generously made themselves
responsible over a period of two years for a large part of the office
expenses connected with the working out and application to the plantation
industries of the Indore Process. They also defrayed the expenses of a
tour to the tea estates of India and Ceylon in 1937. These arrangements
were very kindly made on my behalf by Mr. G. H. Masefield, Chairman of
the Ceylon Tea Plantations Company.
In the work of reducing to order the vast mass of correspondence and
notes on soil fertility' which have accumulated, and in getting the book
into its final shape, I owe much to the ability and devotion of my
private secretary, Mrs. V. M. Hamilton.
A. H. BLACKHEATH,
1 January 1940
In deciding to issue a fifth reprint of my late husband's book,
An Agricultural Testament, I have abstained from introducing any additions
or corrections. To do so would necessitate an almost complete rewriting
of this, the first and perhaps the most trenchant, statement of his views.
Nevertheless, it would be incorrect to deny that the subject matters
treated progressed rapidly even in the course of his own life time; he
himself added to what he said here, and many gallant writers have followed
his lead. A survey of literature presents difficulties, partly owing to
Sir Albert Howard's practice of scattering articles in journals all over
the world. Following on the creation of an Albert Howard Foundation of
Organic Husbandry, the declared aim of which is to continue and make
known the Albert Howard principles, inquiries may be addressed to
the Headquarters of the Foundation at Sharnden Manor, Mayfield, Sussex,
England.
LOUISE E. HOWARD
1949
CONTENTS
I. INTRODUCTION.
PART I THE PART PLAYED BY SOIL FERTILITY IN AGRICULTURE
II. THE NATURE OF SOIL FERTILITY.
III. THE RESTORATION OF FERTILITY.
PART II THE INDORE PROCESS
IV. THE INDORE PROCESS
V. PRACTICAL APPLICATIONS OF THE INDORE PROCESS
VI. DEVELOPMENTS OF THE INDORE PROCESS
VII. DEVELOPMENTS OF THE INDORE PROCESS, GRASS-LAND MANAGEMENT
VIII. DEVELOPMENTS OF THE INDORE PROCESS, THE UTILIZATION OF TOWN WASTES
PART III HEALTH, INDISPOSITION, AND DISEASE IN AGRICULTURE
IX. SOIL AERATION
X. SOME DISEASES OF THE SOIL
XI. THE RETREAT OF THE CROP AND THE ANIMAL BEFORE THE PARASITE
XII. SOIL FERTILITY AND NATIONAL HEALTH.
PART IV AGRICULTURAL RESEARCH
XIII. A CRITICISM OF PRESENT-DAY AGRICULTURAL RESEARCH
XIV. A SUCCESSFUL EXAMPLE OF AGRICULTURAL RESEARCH
PART V CONCLUSIONS AND SUGGESTIONS
XV. A FINAL SURVEY
APPENDIXES
A. COMPOST MANUFACTURE ON A TEA ESTATE IN BENGAL
B. COMPOST MAKING AT CHIPOLI, SOUTHERN RHODESIA
C. THE MANUFACTURE OF HUMUS FROM THE WASTES OF THE TOWN AND THE VILLAGE
=======
CHAPTER I
INTRODUCTION
The maintenance of the fertility of the soil is the first condition of
any permanent system of agriculture. In the ordinary processes of crop
production fertility is steadily lost: its continuous restoration by
means of manuring and soil management is therefore imperative.
In the study of soil fertility the first step is to bring under review
the various systems of agriculture which so far have been evolved. These
fall into four main groups: (1) the methods of Nature--the supreme
farmer--as seen in the primeval forest, in the prairie, and in the ocean;
(2) the agriculture of the nations which have passed away; (3) the
practices of the Orient, which have been almost unaffected by Western
science; and (4) the methods in vogue in regions like Europe and North
America to which a large amount of scientific attention has been paid
during the last hundred years.
NATURE'S METHODS OF SOIL MANAGEMENT
Little or no consideration is paid in the literature of agriculture to
the means by which Nature manages land and conducts her water culture.
Nevertheless, these natural methods of soil management must form the
basis of all our studies of soil fertility.
What are the main principles underlying Nature's agriculture? These can
most easily be seen in operation in our woods and forests.
Mixed farming is the rule: plants are always found with animals: many
species of plants and of animals all live together. In the forest every
form of animal life, from mammals to the simplest invertebrates, occurs.
The vegetable kingdom exhibits a similar range: there is never any
attempt at monoculture: mixed crops and mixed farming are the rule.
The soil is always protected from the direct action of sun, rain, and
wind. In this care of the soil strict economy is the watchword: nothing
is lost. The whole of the energy of sunlight is made use of by the
foliage of the forest canopy and of the undergrowth. The leaves also
break up the rainfall into fine spray so that it can the more easily be
dealt with by the litter of plant and animal remains which provide the
last line of defence of the precious soil. These methods of protection,
so effective in dealing with sun and rain, also reduce the power of the
strongest winds to a gentle air current.
The rainfall in particular is carefully conserved. A large portion is
retained in the surface soil: the excess is gently transferred to the
subsoil and in due course to the streams and rivers. The fine spray
created by the foliage is transformed by the protective ground litter
into thin films of water which move slowly downwards, first into the
humus layer and then into the soil and subsoil. These latter have been
made porous in two ways: by the creation of a well-marked crumb structure
and by a network of drainage and aeration channels made by earthworms and
other burrowing animals. The pore space of the forest soil is at its
maximum so that there is a large internal soil surface over which the
thin films of water can creep. There is also ample humus for the direct
absorption of moisture. The excess drains away slowly by way of the
subsoil. There is remarkably little run-off, even from the primeval rain
forest. When this occurs it is practically clear water. Hardly any soil
is removed. Nothing in the nature of soil erosion occurs. The streams and
rivers in forest areas are always perennial because of the vast quantity
of water in slow transit between the rainstorms and the sea. There is
therefore little or no drought in forest areas because so much of the
rainfall is retained exactly where it is needed. There is no waste
anywhere.
The forest manures itself. It makes its own humus and supplies itself
with minerals. If we watch a piece of woodland we find that a gentle
accumulation of mixed vegetable and animal residues is constantly taking
place on the ground and that these wastes are being converted by fungi
and bacteria into humus. The processes involved in the early stages of
this transformation depend throughout on oxidation: afterwards they take
place in the absence of air. They are sanitary. There is no nuisance of
any kind--no smell, no flies, no dustbins, no incinerators, no artificial
sewage system, no water-borne diseases, no town councils, and no rates.
On the contrary, the forest affords a place for the ideal summer holiday:
sufficient shade and an abundance of pure fresh air. Nevertheless, all
over the surface of the woods the conversion of vegetable and animal
wastes into humus is never so rapid and so intense as during the holiday
months--July to September.
The mineral matter needed by the trees and the undergrowth is obtained
from the subsoil. This is collected in dilute solution in water by the
deeper roots, which also help in anchoring the trees. The details of root
distribution and the manner in which the subsoil is thoroughly combed for
minerals are referred to in a future chapter. Even in soils markedly
deficient in phosphorus trees have no difficulty in obtaining ample
supplies of this element. Potash, phosphate, and other minerals are
always collected in situ and carried by the transpiration current for use
in the green leaves. Afterwards they are either used in growth or
deposited on the floor of the forest in the form of vegetable waste--one
of the constituents needed in the synthesis of humus. This humus is again
utilized by the roots of the trees. Nature's farming, as seen in the
forest, is characterized by two things: (1) a constant circulation of the
mineral matter absorbed by the trees; (2) a constant addition of new
mineral matter from the vast reserves held in the subsoil. There is
therefore no need to add phosphates: there is no necessity for more
potash salts. No mineral deficiencies of any kind occur. The supply of
all the manure needed is automatic and is provided either by humus or by
the soil. There is a natural division of the subject into organic and
inorganic. Humus provides the organic manure: the soil the mineral
matter.
The soil always carries a large fertility reserve. There is no hand to
mouth existence about Nature's farming. The reserves are carried in the
upper layers of the soil in the form of humus. Yet any useless
accumulation of humus is avoided because it is automatically mingled with
the upper soil by the activities of burrowing animals such as earthworms
and insects. The extent of this enormous reserve is only realized when
the trees are cut down and the virgin land is used for agriculture. When
plants like tea, coffee, rubber, and bananas are grown on recently
cleared land, good crops can be raised without manure for ten years or
more. Like all good administrators, therefore, Nature carries strong
liquid reserves effectively invested. There is no squandering of these
reserves to be seen anywhere.
The crops and live stock look after themselves. Nature has never found it
necessary to design the equivalent of the spraying machine and the poison
spray for the control of insect and fungous pests. There is nothing in
the nature of vaccines and serums for the protection of the live stock.
It is true that all kinds of diseases are to be found here and there
among the plants and animals of the forest, but these never assume large
proportions. The principle followed is that the plants and animals can
very well protect themselves even when such things as parasites are to be
found in their midst. Nature's rule in these matters is to live and let
live.
If we study the prairie and the ocean we find that similar principles are
followed. The grass carpet deals with the rainfall very much as the
forest does. There is little or no soil erosion: the run-off is
practically clear water. Humus is again stored in the upper soil. The
best of the grassland areas of North America carried a mixed herbage
which maintained vast herds of bison. No veterinary service was in
existence for keeping these animals alive. When brought into cultivation
by the early settlers, so great was the store of fertility that these
prairie soils yielded heavy crops of wheat for many years without live
stock and without manure.
In lakes, rivers, and the sea mixed farming is again the rule: a great
variety of plants and animals are found living together: nowhere does one
find monoculture. The vegetable and animal wastes are again dealt with by
effective methods. Nothing is wasted. Humus again plays an important part
and is found everywhere in solution, in suspension, and in the deposits
of mud. The sea, like the forest and the prairie, manures itself.
The main characteristic of Nature's farming can therefore be summed up in
a few words. Mother earth never attempts to farm without live stock; she
always raises mixed crops; great pains are taken to preserve the soil and
to prevent erosion; the mixed vegetable and animal wastes are converted
into humus; there is no waste; the processes of growth and the processes
of decay balance one another; ample provision is made to maintain large
reserves of fertility; the greatest care is taken to store the rainfall;
both plants and animals are left to protect themselves against disease
In considering the various man-made systems of agriculture, which so far
have been devised, it will be interesting to see how far Nature's
principles have been adopted, whether they have ever been improved upon,
and what happens when they are disregarded.
THE AGRICULTURE OF THE NATIONS WHICH HAVE PASSED AWAY
The difficulties inherent in the study of the agriculture of the nations
which are no more are obvious. Unlike their buildings, where it is
possible from a critical study of the buried remains of cities to
reproduce a picture of bygone civilizations, the fields of the ancients
have seldom been maintained. The land has either gone back to forest or
has been used for one system of farming after another.
In one case, however, the actual fields of a bygone people have been
preserved together with the irrigation methods by which these lands were
made productive. No written records, alas, have come down to us of the
staircase cultivation of the ancient Peruvians, perhaps one of the oldest
forms of Stone Age agriculture. This arose either in mountains or in the
upland areas under grass because of the difficulty, before the discovery
of iron, of removing the dense forest growth. In Peru irrigated staircase
farming seems to have reached its highest known development. More than
twenty years ago the National Geographical Society of the United States
sent an expedition to study the relics of this ancient method of
agriculture, an account of which was published by O. F. Cook in the
Society's Magazine of May 1916, under the title: 'Staircase Farms of the
Ancients.' The system of the megalithic people of old Peru was to
construct a stairway of terraced fields up the slopes of the mountains,
tier upon tier, sometimes as many as fifty in number. The outer retaining
walls of these terraces were made of large stones which fit into one
another with such accuracy that even at the present day, like those of
the Egyptian pyramids, a knife blade cannot be inserted between them.
After the retaining wall was built, the foundation of the future field
was prepared by means of coarse stones covered with clay. On this basis
layers of soil, several feet thick, originally imported from beyond the
great mountains, were super-imposed and then levelled for irrigation. The
final result was a small flat field with only just sufficient slope for
artificial watering. In other words, a series of huge flower pots, each
provided with ample drainage below, was prepared with incredible labour
by this ancient people for their crops. Such were the megalithic
achievements in agriculture, beside which 'our undertakings sink into
insignificance in face of what this vanished race accomplished. The
narrow floors and steep walls of rocky valleys that would appear utterly
worthless and hopeless to our engineers were transformed, literally made
over, into fertile lands and were the homes of teeming populations in
pre-historic days' (O. F. Cook). The engineers of old Peru did what they
did through necessity because iron, steel, reinforced concrete, and the
modern power units had not been invented. The plunder of the forest soil
was beyond their reach.
These terraced fields had to be irrigated. Water had to be led to them
over immense distances by means of aqueducts. Prescott states that one
which traversed the district of Condesuyu measured between four and five
hundred miles. Cook gives a photograph of one of these channels as a thin
dark line traversing a steep mountain wall many hundreds of feet above
the valley.
These ancient methods of agriculture are represented at the present day
by the terraced cultivation of the Himalayas, of the mountainous areas of
China and Japan, and of the irrigated rice fields so common in the hills
of South India, Ceylon, and the Malayan Archipelago. Conway's
description, published in 1894, of the terraces of Hunza on the
North-West Frontier of India and of the canal, carried for long distances
across the face of precipices to the one available supply of perennial
water--the torrent from the Ultor glacier--tallies almost completely with
what he found in 1901 in the Bolivian Andes. This distinguished scholar
and mountaineer considered that the native population of Hunza of the
present day is living in a stage of civilization that must bear no little
likeness to that of the Peruvians under Inca government. An example of
this ancient method of farming has thus been preserved through the ages.
In a future chapter the relation which exists between the nutritional
value of the food grown on these irrigated terraces and the health of the
people will be discussed. This relic of the past is interesting from the
point of view of quality in food as well as from its historical value.
Some other systems of agriculture of the past have come down to us in the
form of written records which have furnished ample material for
constructive research. In the case of Rome in particular a fairly
complete account of the position of agriculture, from the period of the
monarchy to the fall of the Roman Empire, is available; the facts can be
conveniently followed in the writings of Mommsen, Heitland, and other
scholars. In the case of Rome the Servian Reform (Servius Tullius,
578-534 B.C.) shows very clearly not only that the agricultural class
originally preponderated in the State but also that an effort was made to
maintain the collective body of freeholders as the pith and marrow of the
community. The conception that the constitution itself rested on the
freehold system permeated the whole policy of Roman war and conquest. The
aim of war was to increase the number of its freehold members.
'The vanquished community was either compelled to merge entirely into
the yeomanry of Rome, or, if not reduced to this extremity, it was
required, not to pay a war contribution or a fixed tribute, but to cede
a portion, usually a third part, of its domain, which was thereupon
regularly occupied by Roman farms. Many nations have gained victories
and made conquests as the Romans did; but none has equalled the Roman in
thus making the ground he had won his own by the sweat of his brow, and
in securing by the ploughshare what had been gained by the lance. That
which is gained by war may be wrested from the grasp by war again, but
it is not so with the conquests made by the plough; whilst the Romans
lost many battles, they scarcely ever on making peace ceded Roman soil,
and for this result they were indebted to the tenacity with which the
farmers clung to their fields and homesteads. The strength of man and of
the State lies in their dominion over the soil; the strength of Rome was
built on the most extensive and immediate mastery of her citizens over
the soil, and on the compact unity of the body which thus acquired so
firm a hold.' (Mommsen.)
These splendid ideals did not persist. During the period which elapsed
between the union of Italy and the subjugation of Carthage, a gradual
decay of the farmers set in; the small-holdings ceased to yield any
substantial clear return; the cultivators one by one faced ruin; the
moral tone and frugal habits of the earlier ages of the Republic were
lost; the land of the Italian farmers became merged into the larger
estates. The landlord capitalist became the centre of the subject. He
not only produced at a cheaper rate than the farmer because he had more
land, but he began to use slaves. The same space which in the olden
time, when small-holdings prevailed, had supported from a hundred to a
hundred and fifty families was now occupied by one family of free
persons and about fifty, for the most part unmarried, slaves. 'If this
was the remedy by which the decaying national economy was to be restored
to vigour, it bore, unhappily, an aspect of extreme resemblance to
disease' (Mommsen). The main causes of this decline appear to have been
fourfold: the constant drain on the manhood of the country-side by the
legions, which culminated in the two long wars with Carthage; the
operations of the Roman capitalist landlords which 'contributed quite as
much as Hamilcar and Hannibal to the decline in the vigour and the
number of the Italian people' (Mommsen); failure to work out a balanced
agriculture between crops and live stock and to maintain the fertility
of the soil; the employment of slaves instead of free labourers. During
this period the wholesale commerce of Latium passed into the hands of
the large landed proprietors who at the same time were the speculators
and capitalists. The natural consequence was the destruction of the
middle classes, particularly of the small-holders, and the development
of landed and moneyed lords on the one hand and of an agricultural
proletariat on the other. The power of capital was greatly enhanced by
the growth of the class of tax-farmers and contractors to whom the State
farmed out its indirect revenues for a fixed sum. Subsequent political
and social conflicts did not give real relief to the agricultural
community. Colonies founded to secure Roman sovereignty over Italy
provided farms for the agricultural proletariat, but the root causes of
the decline in agriculture were not removed in spite of the efforts of
Cato and other reformers. A capitalist system of which the apparent
interests were fundamentally opposed to a sound agriculture remained
supreme. The last half of the second century saw degradation and more
and more decadence. Then came Tiberius Gracchus and the Agrarian Law
with the appointment of an official commission to counteract the
diminution of the farmer class by the comprehensive establishment of new
small-holdings from the whole Italian landed property at the disposal of
the State: eighty thousand new Italian farmers were provided with land.
These efforts to restore agriculture to its rightful place in the State
were accompanied by many improvements in Roman agriculture which,
unfortunately, were most suitable for large estates. Land no longer able
to produce corn became pasture; cattle now roamed over large ranches;
the vine and the olive were cultivated with commercial success. These
systems of agriculture, however, had to be carried on with slave labour,
the supply of which had to be maintained by constant importation. Such
extensive methods of farming naturally failed to supply sufficient food
for the population of Italy. Other countries were called upon to furnish
essential foodstuffs; province after province was conquered to feed the
growing proletariat with corn. These areas in turn slowly yielded to the
same decline which had taken place in Italy. Finally the wealthy classes
abandoned the depopulated remnants of the mother country and built
themselves a new capital at Constantinople. The situation had to be
saved by a migration to fresh lands. In their new capital the Romans
relied on the unexhausted fertility of Egypt as well as on that of Asia
Minor and the Balkan and Danubian provinces.
Judged by the ordinary standards of achievement the agricultural history
of the Roman Empire ended in failure due to inability to realize the
fundamental principle that the maintenance of soil fertility coupled with
the legitimate claims of the agricultural population should never have
been allowed to come in conflict with the operations of the capitalist.
The most important possession of a country is its population. If this is
maintained in health and vigour everything else will follow; if this is
allowed to decline nothing, not even great riches, can save the country
from eventual ruin. It follows, therefore, that the strongest possible
support of capital must always be a prosperous and contented
country-side. A working compromise between agriculture and finance should
therefore have been evolved. Failure to achieve this naturally ended in
the ruin of both.
THE PRACTICES OF THE ORIENT
In the agriculture of Asia we find ourselves confronted with a system of
peasant farming which in essentials soon became stabilized. What is
happening to-day in the small fields of India and China took place many
centuries ago. There is here no need to study historical records or to
pay a visit to the remains of the megalithic farming of the Andes. The
agricultural practices of the Orient have passed the supreme test--they
are almost as permanent as those of the primeval forest, of the prairie
or of the ocean. The small-holdings of China, for example, are still
maintaining a steady output and there is no loss of fertility after forty
centuries of management. What are the chief characteristics of this
Eastern farming?
The holdings are minute. Taking India as an example, the relation between
man power and cultivated area is referred to in the Census Report of 1931
as follows: 'For every agriculturalist there is 2.9 acres of cropped land
of which 0.65 of an acre is irrigated. The corresponding figures of 1921
are 2.7 and 0.61.' These figures illustrate how intense is the struggle
for existence in this portion of the tropics. These small-holdings are
often cultivated by extensive methods (those suitable for large areas)
which utilize neither the full energies of man or beast nor the potential
fertility of the soil.
If we turn to the Far East, to China and Japan, a similar system of
small-holdings is accompanied by an even more intense pressure of
population both human and bovine. In the introduction to FARMERS OF FORTY
CENTURIES, King states that the three main islands of Japan had in 1907 a
population of 46,977,000, maintained on 20,000 square miles of cultivated
fields. This is at the rate of 2,349 to the square mile or more than
three people to each acre. In addition, Japan fed on each square mile of
cultivation a very large animal population--69 horses and 56 cattle,
nearly all employed in labour; 825 poultry; 13 swine, goats, and sheep.
Though no accurate statistics are available in China, the examples quoted
by King reveal a condition of affairs not unlike that in Japan. In the
Shantung Province a farmer with a family of twelve kept one donkey, one
cow, and two pigs on 2.5 acres of cultivated land--a density of
population at the rate of 3,072 people, 256 donkeys, 256 cattle, and 512
pigs per square mile. The average of seven Chinese holdings visited gave
a maintenance capacity of 1,783 people, 212 cattle or donkeys, and 399
pigs--nearly 2,000 consumers and 400 rough food transformers per square
mile of farmed land. In comparison with these remarkable figures, the
corresponding statistics for 1900 in the case of the United States per
square mile were: population 61, horses and mules 30.
Food and forage crops are predominant. The primary function of Eastern
agriculture is to supply the cultivators and their cattle with food. This
automatically follows because of the pressure of the population on the
land: the main hunger the soil has to appease is that of the stomach. A
subsidiary hunger is that of the machine which needs raw materials for
manufacture. This extra hunger is new but has developed considerably
since the opening of the Suez Canal in 1869 (by which the small fields of
the cultivator have been brought into effective contact with the markets
of the West) and the establishment of local industries like cotton and
jute. To both these hungers soil fertility has to respond. We know from
long experience that the fields of India can respond to the hunger of the
stomach. Whether they can fulfil the added demands of the machine remains
to be seen. The Suez Canal has only been in operation for seventy years.
The first cotton mill in India was opened in 1818 at Fort Gloster, near
Calcutta. The jute industry of Bengal has grown up within a century. Jute
was first exported in 1838. The first jute mill on the Hoogly began
operations in 1855. These local industries as well as the export trade in
raw products for the use of the factories of the West are an extra drain
on soil fertility. Their future well-being and indeed their very
existence is only possible provided adequate steps are taken to maintain
this fertility. There is obviously no point in establishing cotton and
jute mills in India, in founding trading agencies like those of Calcutta
and in building ships for the conveyance of raw products unless such
enterprises are stable and permanent. It would be folly and an obvious
waste of capital to pursue such activities if they are founded only on
the existing store of soil fertility. All concerned in the hunger of the
machine--government, financiers, manufacturers, and distributors--must
see to it that the fields of India are equal to the new burden which has
been thrust upon her during the last fifty years or so. The demands of
commerce and industry on the one hand and the fertility of the soil on
the other must be maintained in correct relation the one to the other.
The response of India to the two hungers--the stomach and the
machine--will be evident from a study of Table I, in which the area in
acres under food and fodder crops is compared with that under money
crops.
The chief food crops in order of importance are rice, pulses millets,
wheat, and fodder crops. The money crops are more varied; cotton and oil
seeds are the most important, followed by jute and other fibres, tobacco,
tea, coffee, and opium. It will be seen that food and fodder crops
comprise 86 per cent. of the total area under crops and that money crops,
as far as extent is concerned, are less important, and constitute only
one-seventh of the total cultivated area.
TABLE 1
Agricultural Statistics of British India, 1935-6
Area, in acres, under food and fodder crops
Rice 79,888,000
Millets 38,144,000
Wheat 25,150,000
Gram 14,897,000
Pulses and other food grains 29,792,000
Fodder crops 10,791,000
Condiments, spices, fruits, vegetables
and miscellaneous food crops 8,308,000
Barley 6,178,000
Maize 6,211,000
Sugar 4,038,000
Total food and fodder crops 223,397,000
Area, in acres, under money crops
Cotton 15,761,000
Oil seeds, chiefly ground-nuts,
sesamum, rape, mustard and linseed 15,662,000
Jute and other fibres 2,706,000
Dyes, tanning materials, drugs,
narcotics, and miscellaneous 1,458,000
Tobacco 1,230,000
Tea 787,000
Coffee 97,000
Indigo 40,000
Opium 10,000
Total money crops 37,751,000
One interesting change in the production of Indian food crops has taken
place during the last twenty-five years. The output of sugar used to be
insufficient for the towns, and large quantities were imported from Java,
Mauritius, and the continent of Europe. To-day, thanks to the work at
Shahjahanpur in the United Provinces, the new varieties of cane bred at
Coimbatore and the protection now enjoyed by the sugar industry, India is
almost self-supporting as far as sugar is concerned. The pre-war average
amount of sugar imported was 634,000 tons; in 1937-8 the total had fallen
to 14,000 tons.
Mixed crops are the rule. In this respect the cultivators of the Orient
have followed Nature's method as seen in the primeval forest. Mixed
cropping is perhaps most universal when the cereal crop is the main
constituent. Crops like millets, wheat, barley, and maize are mixed with
an appropriate subsidiary pulse, sometimes a species that ripens much
later than the cereal. The pigeon pea (Cajanus indicus Spreng.), perhaps
the most important leguminous crop of the Gangetic alluvium, is grown
either with millets or with maize. The mixing of cereals and pulses
appears to help both crops. When the two grow together the character of
the growth improves. Do the roots of these crops excrete materials useful
to each other? Is the mycorrhizal association found in the roots of these
tropical legumes and cereals the agent involved in this excretion?
Science at the moment is unable to answer these questions: she is only
now beginning to investigate them Here we have another instance where the
peasants of the East have anticipated and acted upon the solution of one
of the problems which Western science is only just beginning to
recognize. Whatever may be the reason why crops thrive best when
associated in suitable combinations, the fact remains that mixtures
generally give better results than monoculture. This is seen in Great
Britain in the growth of dredge corn, in mixed crops of wheat and beans,
vetches and rye, clover and rye-grass, and in intensive vegetable growing
under glass. The produce raised under Dutch lights has noticeably
increased since the mixed cropping of the Chinese vegetable growers of
Australia has been copied. (Mr. F. A. Secrett was, I believe, the first
to introduce this system on a large scale into Great Britain. He informed
me that he saw it for the first time at Melbourne.)
A balance between live stock and crops is always maintained. Although
crops are generally more important than animals in Eastern agriculture,
we seldom or never find crops without animals. This is because oxen are
required for cultivation and buffaloes for milk. (The buffalo is the
milch cow of the Orient and is capable not only of useful labour in the
cultivation of rice, but also of living and producing large quantities of
rich milk on a diet on which the best dairy cows of Europe and America
would starve. The acclimatization of the Indian buffalo in the villages
of the Tropics--Africa, Central America, the West Indies in
particular--would do much to improve the fertility of the soil and the
nutrition of the people.)
Nevertheless, the waste products of the animal, as is often the case in
other parts of the world, are not always fully utilized for the land. The
Chinese have for ages past recognized the importance of the urine of
animals and the great value of animal wastes in the preparation of
composts. In India far less attention is paid to these wastes and a large
portion of the cattle dung available is burnt for fuel. On the other
hand, in most Oriental countries human wastes find their way back to the
land. In China these are collected for manuring the crops direct. In
India they are concentrated on the zone of highly manured land
immediately round each village. If the population or a portion of it
could be persuaded to use a more distant zone for a few years, the area
of village lands under intensive agriculture could at least be doubled.
Here is an opportunity for the new system of government in India to raise
production without the expenditure of a single rupee. In India there are
500,000 villages each of which is surrounded by a zone of very fertile
land which is constantly being over-manured by the habits of the people.
If we examine the crops grown on this land we find that the yields are
high and the plants are remarkably free from disease. Although half a
million examples of the connexion between a fertile soil and a healthy
plant exist in India alone, and these natural experiments have been in
operation for centuries before experiment stations like Rothamsted were
ever thought of, modern agricultural science takes no notice of the
results and resolutely refuses to accept them as evidence, largely
because they lack the support furnished by the higher mathematics. They
also dispose of one of the ideas of the disciples of Rudolph Steiner, who
argue that the use of human wastes in agriculture is harmful.
Leguminous plants are common. Although it was not till 1888, after a
protracted controversy lasting thirty years, that Western science finally
accepted as proved the important part played by pulse crops in enriching
the soil, centuries of experience had taught the peasants of the East the
same lesson. The leguminous crop in the rotation is everywhere one of
their old fixed practices. In some areas, such as the Indo-Gangetic
plain, one of these pulses--the pigeon pea--is also made use of as a
subsoil cultivator. The deep spreading root system is used to promote the
aeration of the closely packed silt soils, which so closely resemble
those of the Holland Division of Lincolnshire in Great Britain.
Cultivation is generally superficial and is carried out by wooden ploughs
furnished with an iron point. Soil-inverting ploughs, as used in the West
for the destruction of weeds, have never been designed by Eastern
peoples. The reasons for this appear to be two: (1) soil inversion for
the destruction of weeds is not necessary in a hot climate where the same
work is done by the sun for nothing; (2) the preservation of the level of
the fields is essential for surface drainage, for preventing local
waterlogging, and for irrigation. Another reason for this surface
cultivation has recently been pointed out. The store of nitrogen in the
soil in the form of organic matter has to be carefully conserved: it is
part of the cultivator's working capital. Too much cultivation and deep
ploughing would oxidize this reserve and the balance of soil fertility
would soon be destroyed.
Rice is grown whenever possible. By far the most important crop in the
East is rice. In India, as has already been pointed out, the production
of rice exceeds that of any two food crops put together. Whenever the
soil and water supply permit, rice is invariably grown. A study of this
crop is illuminating. At first sight rice appears to contradict one of
the great principles of the agricultural science of the Occident, namely,
the dependence of cereals on nitrogenous manures. Large crops of rice are
produced in many parts of India on the same land year after year without
the addition of any manure whatever. The rice fields of the country
export paddy in large quantities to the centres of population or abroad,
but there is no corresponding import of combined nitrogen.
Taking Burma as an example of an area exporting rice beyond seas, during
the twenty years ending 1924, about 25,000,000 tons of paddy have been
exported from a tract roughly 10,000,000 acres in area. As unhusked rice
contains about 1.2 per cent. of nitrogen the amount of this element,
shipped overseas during twenty years or destroyed in the burning of the
husk, is in the neighbourhood of 300,000 tons. As this constant drain of
nitrogen is not made up for by the import of manure, we should expect to
find a gradual loss of fertility. Nevertheless, this does not take place
either in Burma or in Bengal, where rice has been grown on the same land
year after year for centuries. Clearly the soil must obtain fresh
supplies of nitrogen from somewhere, otherwise the crop would cease to
grow. The only likely source is fixation from the atmosphere, probably in
the submerged algal film on the surface of the mud. This is one of the
problems of tropical agriculture which is now being investigated.
Where does the rice crop obtain its nitrogen? One source in all
probability is fixation from the atmosphere in the submerged algal film
on the surface of the mud. Another is the rice nursery itself, where the
seedlings are raised on land heavily manured with cattle dung. Large
quantities of nitrogen and other nutrients are stored in the seedling
itself; this at transplanting time contains a veritable arsenal of
reserves of all kinds which carry the plant successfully through this
process and probably also furnish some of the nitrogen needed during
subsequent growth. The manuring of the rice seedling illustrates a very
general principle in agriculture, namely, the importance of starting a
crop in a really fertile soil and so arranging matters that the plant can
absorb a great deal of what it needs as early as possible in its
development.
There is an adequate supply of labour. Labour is everywhere abundant, as
would naturally follow from the great density of the rural population.
Indeed, in India it is so great that if the leisure time of the
cultivators and their cattle for a single year could be calculated as
money at the local rates a perfectly colossal figure would be obtained.
This leisure, however, is not altogether wasted. It enables the
cultivators and their oxen to recover from the periods of intensive work
which precede the sowing of the crops and which are needed at harvest
time. At these periods time is everything: everybody works from sunrise
to sunset. The preparation of the land and the sowing of the crops need
the greatest care and skill; the work must be completed in a very short
time so that a large labour force is essential.
It will be observed that in this peasant agriculture the great pressure
of population on the soil results in poverty, most marked where, as in
India, extensive methods are used on small-holdings which really need
intensive farming. It is amazing that in spite of this unfavourable
factor soil fertility should have been preserved for centuries: this is
because natural means have been used and not artificial manures. The
crops are able to withstand the inroads of insects and fungi without a
thin film of protective poison.
THE AGRICULTURAL METHODS OF THE OCCIDENT
If we take a wide survey of the contribution which is being made by the
fields of the West, we find that they are engaged in trying to satisfy no
less than three hungers: (1) the local hunger of the rural population,
including the live stock; (2) the hunger of the growing urban areas, the
population of which is unproductive from the point of view of soil
fertility; and (3) the hunger of the machine avid for a constant stream
of the raw materials required for manufacture. The urban population
during the last century has grown out of all knowledge; the needs of the
machine increase as it becomes more and more efficient; falling profits
are met by increasing the output of manufactured articles. All this adds
to the burden on the land and to the calls on its fertility. It will not
be without interest to analyse critically the agriculture of the West and
see how it is fitting itself for its growing task. This can be done by
examining its main characteristics. These are as follows:
The holding tends to increase in size. There is a great variation in the
size of the agricultural holdings of the West from the small family units
of France and Switzerland to the immense collective farms of Russia and
the spacious ranches of the United States and Argentina. Side by side
with this growth in the size of the farm is the diminution of the number
of men per square mile. In Canada, for example, the number of workers per
1,000 acres of cropped land fell from 26 in 1911 to 16 in 1926. Since
these data were published the size of the working population has shrunk
still further. This state of things has arisen from the scarcity and
dearness of labour which has naturally led to the study of labour-saving
devices.
Monoculture is the rule. Almost everywhere crops are grown in pure
culture. Except in temporary leys, mixed crops are rare. On the rich
prairie lands of North America even rotations are unknown: crops of wheat
follow one another and no attempt is made to convert the straw into humus
by means of the urine and dung of cattle. The straw is a tiresome
encumbrance and is burnt off annually.
The machine is rapidly replacing the animal. Increasing mechanization is
one of the main features of Western agriculture. Whenever a machine can
be invented which saves human or animal labour its spread is rapid.
Engines and motors of various kinds are the rule everywhere. The
electrification of agriculture is beginning. The inevitable march of the
combine harvester in all the wheat-producing areas of the world is one of
the latest examples of the mechanization of the agriculture of the West.
Cultivation tends to be quicker and deeper. There is a growing feeling
that the more and the deeper the soil is stirred the better will be the
crop. The invention of the gyrotiller, a heavy and expensive soil churn,
is one of the answers to this demand. The slaves of the Roman Empire have
been replaced by mechanical slaves. The replacement of the horse and the
ox by the internal combustion engine and the electric motor is, however,
attended by one great disadvantage. These machines do not void urine and
dung and so contribute nothing to the maintenance of soil fertility. In
this sense the slaves of Western agriculture are less efficient than
those of ancient Rome.
Artificial manures are widely used. The feature of the manuring of the
West is the use of artificial manures. The factories engaged during the
Great War in the fixation of atmospheric nitrogen for the manufacture of
explosives had to find other markets, the use of nitrogenous fertilizers
in agriculture increased, until to-day the majority of farmers and market
gardeners base their manurial programme on the cheapest forms of nitrogen
(N), phosphorus (P), and potassium (K) on the market. What may be
conveniently described as the NPK mentality dominates farming alike in
the experimental stations and the country-side. Vested interests,
entrenched in time of national emergency, have gained a stranglehold.
Artificial manures involve less labour and less trouble than farm-yard
manure. The tractor is superior to the horse in power and in speed of
work: it needs no food and no expensive care during its long hours of
rest. These two agencies have made it easier to run a farm. A
satisfactory profit and loss account has been obtained. For the moment
farming has been made to pay. But there is another side to this picture.
These chemicals and these machines can do nothing to keep the soil in
good heart. By their use the processes of growth can never be balanced by
the processes of decay. All that they can accomplish is the transfer of
the soil's capital to current account. That this is so will be much
clearer when the attempts now being made to farm without any animals at
all march to their inevitable failure.
Diseases are on the increase. With the spread of artificials and the
exhaustion of the original supplies of humus, carried by every fertile
soil, there has been a corresponding increase in the diseases of crops
and of the animals which feed on them. If the spread of foot-and-mouth
disease in Europe and its comparative insignificance among well fed
animals in the East are compared, or if the comparison is made between
certain areas in Europe, the conclusion is inevitable that there must be
an intimate connexion between faulty methods of agriculture and animal
disease. In crops like potatoes and fruit, the use of the poison spray
has closely followed the reduction in the supplies of farm-yard manure
and the diminution of fertility.
Food preservation processes are also on the increase. A feature of the
agriculture of the West is the development of food preservation processes
by which the journey of products like meat, milk, vegetables, and fruit
between the soil and the stomach is prolonged. This is done by freezing,
by the use of carbon dioxide, by drying, and by canning. Although food is
preserved for a time in this way, what is the effect of these processes
on the health of the community during a period of, say, twenty-five
years? Is it possible to preserve the first freshness of food? If so then
science will have made a very real contribution.
Science has been called in to help production. Another of the features of
the agriculture of the West is the development of agricultural science.
Efforts have been made to enlist the help of a number of separate
sciences in studying the problems of agriculture and in increasing the
production of the soil. This has entailed the foundation of numerous
experiment stations which every year pour out a large volume of advice in
the shape of printed matter.
These mushroom ideas of agriculture are failing; mother earth deprived of
her manurial rights is in revolt; the land is going on strike; the
fertility of the soil is declining. An examination of the areas which
feed the population and the machines of a country like Great Britain
leaves no doubt that the soil is no longer able to stand the strain. Soil
fertility is rapidly diminishing, particularly in the United States,
Canada, Africa, Australia, and New Zealand. In Great Britain itself real
farming has already been given up except on the best lands. The loss of
fertility all over the world is indicated by the growing menace of soil
erosion. The seriousness of the situation is proved by the attention now
being paid to this matter in the press and by the various
Administrations. In the United States, for example, the whole resources
of government are being mobilized to save what is left of the good earth.
The agricultural record has been briefly reviewed from the standpoint of
soil fertility. The main characteristics of the various methods of
agriculture have been summarized. The most significant of these are the
operations of Nature as seen in the forest. There the fullest use is made
of sunlight and rainfall in raising heavy crops of produce and at the
same time not only maintaining fertility but actually building up large
reserves of humus. The peasants of China, who pay great attention to the
return of all wastes to the land, come nearest to the ideal set by
Nature. They have maintained a large population on the land without any
falling off in fertility. The agriculture of ancient Rome failed because
it was unable to maintain the soil in a fertile condition. The farmers of
the West are repeating the mistakes made by Imperial Rome. The soils of
the Roman Empire, however, were only called upon to assuage the hunger of
a relatively small population. The demands of the machine were then
almost non-existent. In the West there are relatively more stomachs to
fill while the growing hunger of the machine is an additional burden on
the soil. The Roman Empire lasted for eleven centuries. How long will the
supremacy of the West endure? The answer depends on the wisdom and
courage of the population in dealing with the things that matter. Can
mankind regulate its affairs so that its chief possession--the fertility
of the soil--is preserved? On the answer to this question the future of
civilization depends.
BIBLIOGRAPHY
Agricultural Statistics of India, 1, Delhi, 1938.
HOWARD, A., and HOWARD, G. L. C. The Development of Indian
Agriculture, Oxford University Press, 1929.
KING, F. H. Farmers of Forty Centuries or Permanent Agriculture
in China, Korea, and Japan, London, 1916.
LYMINGTON, VISCOUNT. Famine in England, London, 1938.
MOMMSEN, THEODOR. The History of Rome, transl. Dickson, London, 1894.
WRENCH, G. T. The Wheel of Health, London, 1938.
PART I THE PART PLAYED BY SOIL FERTILITY IN AGRICULTURE
CHAPTER II
THE NATURE OF SOIL FERTILITY
What is this soil fertility? What exactly does it mean? How does it
affect the soil, the crop, and the animal? How can we best investigate
it? An attempt will be made in this chapter to answer these questions and
to show why soil fertility must be the basis of any permanent system of
agriculture.
The nature of soil fertility can only be understood if it is considered
in relation to Nature's round. In this study we must at the outset
emancipate ourselves from the conventional approach to agricultural
problems by means of the separate sciences and above all from the
statistical consideration of the evidence afforded by the ordinary field
experiment. Instead of breaking up the subject into fragments and
studying agriculture in piecemeal fashion by the analytical methods of
science, appropriate only to the discovery of new facts, we must adopt a
synthetic approach and look at the wheel of life as one great subject and
not as if it were a patchwork of unrelated things.
All the phases of the life cycle are closely connected; all are integral
to Nature's activity; all are equally important; none can be omitted. We
have therefore to study soil fertility in relation to a natural working
system and to adopt methods of investigation in strict relation to such a
subject. We need not strive after quantitative results: the qualitative
will often serve. We must look at soil fertility as we would study a
business where the profit and loss account must be taken along with the
balance-sheet, the standing of the concern, and the method of management.
It is the 'altogetherness' which matters in business, not some particular
transaction or the profit or loss of the current year. So it is with soil
fertility. We have to consider the wood, not the individual trees.
The wheel of life is made up of two processes--growth and decay. The one
is the counterpart of the other.
Let us first consider growth. The soil yields crops; these form the food
of animals: crops and animals are taken up into the human body and are
digested there. The perfectly grown, normal, vigorous human being is the
highest natural development known to us. There is no break in the chain
from soil to man; this section of the wheel of life is uninterrupted
throughout; it is also an integration; each step depends on the last. It
must therefore be studied as a working whole.
The energy for the machinery of growth is derived from the sun; the
chlorophyll in the green leaf is the mechanism by which this energy is
intercepted; the plant is thereby enabled to manufacture food--to
synthesize carbohydrates and proteins from the water and other substances
taken up by the roots and the carbon dioxide of the atmosphere. The
efficiency of the green leaf is therefore of supreme importance; on it
depends the food supply of this planet, our well-being, and our
activities. There is no alternative source of nutriment. Without sunlight
and the green leaf our industries, our trade, and our possessions would
soon be useless.
The chief factors on which the work of the green leaf depends are the
condition of the soil and its relation to the roots of the plant. The
plant and the soil come into gear by means of the root system in two
ways--by the root hairs and by the mycorrhizal association. The first
condition for this gearing is that the internal surface of the soil--the
pore space--shall be as large as possible throughout the life of the
crop. It is on the walls of this pore space, which are covered with thin
water films, that the essential activities of the soil take place. The
soil population, consisting mainly of bacteria, fungi and protozoa, carry
on their life histories in these water films.
The contact between the soil and the plant which is best understood takes
place by means of the root hairs. These are prolongations of the outer
layer of cells of the young root. Their duty is to absorb from the thin
films of moisture on the walls of the pore space the water and dissolved
salts needed for the work of the green leaves: no actual food can reach
the plant in this way, only simple things which are needed by the green
leaf to synthesize food. The activities of the pore space depend on
respiration for which adequate quantities of oxygen are essential. A
corresponding amount of carbon dioxide is the natural by-product. To
maintain the oxygen supply and to reduce the amount of carbon dioxide,
the pore spaces must be kept in contact with the atmosphere. The soil
must be ventilated. Hence the importance of cultivation.
As most of the soil organisms possess no chlorophyll, and, moreover, have
to work in the dark, they must be supplied with energy. This is obtained
by the oxidation of humus--the name given to a complex residue of partly
oxidized vegetable and animal matter together with the substances
synthesized by the fungi and bacteria which break down these wastes. This
humus also helps to provide the cement which enables the minute mineral
soil particles to aggregate into larger compound particles and so
maintain the pore space. If the soil is deficient in humus, the volume of
the pore space is reduced; the aeration of the soil is impeded; there is
insufficient organic matter for the soil population; the machinery of the
soil runs down; the supply of oxygen, water, and dissolved salts needed
by the root hairs is reduced; the synthesis of carbohydrates and proteins
in the green leaf proceeds at a lower tempo; growth is affected. Humus is
therefore an essential material for the soil if the first phase of the
life cycle is to function.
There is another reason why humus is important. Its presence in the soil
is an essential condition for the proper functioning of the second
contact between soil and plant--the mycorrhizal relationship. By means of
this connexion certain soil fungi, which live on humus, are able to
invade the living cells of the young roots and establish an intimate
relation with the plant, the details of which symbiosis are still being
investigated and discussed. Soil fungus and plant cells live together in
closer partnership than the algal and fungous constituents of the lichen
do. How the fungus benefits has yet to be determined. How the plant
profits is easier to understand. If a suitable preparation of such roots
is examined under the microscope, all stages in the digestion of the
fungous mycelium can be seen. At the end of the partnership the root
consumes the fungus and in this manner is able to absorb the
carbohydrates and proteins which the fungus obtains partly from the humus
in the soil. The mycorrhizal association therefore is the living bridge
by which a fertile soil (one rich in humus) and the crop are directly
connected and by which food materials ready for immediate use can be
transferred from soil to plant. How this association influences the work
of the green leaf is one of the most interesting problems science has now
to investigate. Is the effective synthesis of carbohydrates and proteins
in the green leaf dependent on the digestion products of these soil
fungi? It is more than probable that this must prove to be the case. Are
these digestion products at the root of disease resistance and quality?
It would appear so. If this is the case it would follow that on the
efficiency of this mycorrhizal association the health and well-being of
mankind must depend.
In a fertile soil the soil and the plant come into gear in two ways
simultaneously. In establishing and maintaining these contacts humus is
essential. It is therefore a key material in the life cycle. Without this
substance the wheel of life cannot function effectively.
The processes of decay which round off and complete the wheel of life can
be seen in operation on the floor of any woodland. This has already been
discussed. It has been shown how the mixed animal and vegetable wastes
are converted into humus and how the forest manures itself.
Such are the essential facts in the wheel of life. Growth on the one
side: decay on the other. In Nature's farming a balance is struck and
maintained between these two complementary processes. The only man-made
systems of agriculture--those to be found in the East--which have stood
the test of time have faithfully copied this rule in Nature. It follows
therefore that the correct relation between the processes of growth and
the processes of decay is the first principle of successful farming.
Agriculture must always be balanced. If we speed up growth we must
accelerate decay. If, on the other hand, the soil's reserves are
squandered, crop production ceases to be good farming: it becomes
something very different. The farmer is transformed into a bandit.
It is now possible to define more clearly the meaning of soil fertility.
It is the condition of a soil rich in humus in which the growth processes
proceed rapidly, smoothly, and efficiently. The term therefore connotes
such things as abundance, high quality, and resistance to disease. A soil
which grows to perfection a wheat crop--the food of man--is described
fertile. A pasture on which meat and milk of the first class are produced
falls into the same category. An area under market-garden crops on which
vegetables of the highest quality are raised has reached the peak as
regards fertility.
Why does soil fertility so markedly influence the soil, the plant, and
the animal? By virtue of the humus it contains. The nature and properties
of this substance as well as the products of its decomposition are
therefore important. These matters must now be considered.
What is humus? A reply to this question has been rendered easier by the
appearance in 1938 of the second edition of Waksman's admirable monograph
on humus in which the results of no less than 1311 original papers have
been reduced to order. Waksman defines humus as
'a complex aggregate of brown to dark-coloured amorphous substances which
have originated during the decomposition of plant and animal residues by
micro-organisms, under aerobic and anaerobic conditions, usually in
soils, composts, peat bogs, and water basins. Chemically, humus consists
of various constituents of the original plant material resistant to
further decomposition; of substances undergoing decomposition; of
complexes resulting from decomposition either by processes of hydrolysis
or by oxidation and reduction; and of various compounds synthesized by
micro-organisms. Humus is a natural body; it is a composite entity, just
as are plant, animal, and microbial substances; it is even much more
complex chemically, since all these materials contribute to its
formation. Humus possesses certain specific physical, chemical, and
biological properties which make it distinct from other natural organic
bodies. Humus, in itself or by interaction with certain inorganic
constituents of the soil, forms a complex colloidal system, the different
constituents of which are held together by surface forces; this system is
adaptable to changing conditions of reaction, moisture, and action by
electrolytes. The numerous activities of the soil micro-organisms take
place in this system to a large extent.'
Viewed from the standpoint of chemistry and physics humus is therefore
not a simple substance: it is made up from a group of very complex
organic compounds depending on the nature of the residues from which it
is formed, on the conditions under which decomposition takes place, and
on the extent to which the processes of decay have proceeded. Humus,
therefore, cannot be exactly the same thing everywhere. It is bound to be
a creature of circumstance. Moreover it is alive and teems with a vast
range of micro-organisms which derive most of their nutriment from this
substratum. Humus in the natural state is dynamic, not static. From the
point of view of agriculture, therefore, we are dealing not with simple
dead matter like a sack of sulphate of ammonia, which can be analysed and
valued according to its chemical composition, but with a vast organic
complex in which an important section of the farmer's invisible labour
force--the organisms which carry on the work of the soil--is temporarily
housed. Humus, therefore, involves the element of labour; in this respect
also it is one of the most important factors on the farm.
It is essential at this point to pay some attention to the manysided
properties of humus and to realize how profoundly it differs from a
chemical manure. At the moment all over the world field trials--based on
mere nitrogen content--are in progress for comparing, on the current
crop, dressings of humus and various artificial manures. A mere glance at
the properties of humus will show that such field trials are based on a
fundamental misconception of what soil fertility implies and are
misleading and therefore useless.
The properties of humus have been summed up by Waksman as follows:
1. Humus possesses a dark brown to black colour.
2. Humus is practically insoluble in water, although a part of it may go
into colloidal solution in pure water. Humus dissolves to a large extent
in dilute alkali solutions, especially on boiling, giving a dark coloured
extract; a large part of this extract precipitates when the alkali
solution is neutralized by mineral acids.
3. Humus contains a somewhat larger amount of carbon than do plant,
animal, and microbial bodies; the carbon content of humus is usually
about 55 to 56 per cent., and frequently reaches 58 per cent.
'4. Humus contains considerable nitrogen, usually about 3 to 6 per cent.
The nitrogen concentration may be frequently less than this figure; in
the case of certain high-moor peats, for example, it may be only 0.5-0.8
per cent. It may also be higher, especially in sub-soils, frequently
reaching 10 to 12 per cent.
'5. Humus contains the elements carbon and nitrogen in proportions which
are close to 10:1; this is true of many soils and of humus in sea
bottoms. This ratio varies considerably with the nature of the humus, the
stage of its decomposition, the nature and depth of soil from which it is
obtained, the climatic and other environmental conditions under which it
is formed.
6. Humus is not in a static, but rather in a dynamic, condition, since it
is constantly formed from plant and animal residues and is continuously
decomposed further by micro-organisms.
7. Humus serves as a source of energy for the development of various
groups of micro-organisms, and during decomposition gives off a
continuous stream of carbon dioxide and ammonia.
8. Humus is characterized by a high capacity of base-exchange, of
combining with various other soil constituents, of absorbing water, and
of swelling, and by other physical and physico-chemical properties which
make it a highly valuable constituent of substrates which support plant
and animal life.'
To this list of properties must be added the role of humus as a cement in
creating and maintaining the compound soil particles so important in the
maintenance of tilth.
The effect of humus on the crop is nothing short of profound. The farmers
and peasants who live in close touch with Nature can tell by a glance at
the crop whether or not the soil is rich in humus. The habit of the plant
then develops something approaching personality; the foliage assumes a
characteristic set; the leaves acquire the glow of health; the flowers
develop depth of colour; the minute morphological characters of the whole
of the plant organs become clearer and sharper. Root development is
profuse: the active roots exhibit not only turgidity but bloom.
The influence of humus on the plant is not confined to the outward
appearance of the various organs. The quality of the produce is also
affected. Seeds are better developed, and so yield better crops and also
provide live stock with a satisfaction not conferred by the produce of
worn-out land. The animals need less food if it comes from fertile soil.
Vegetables and fruit grown on land rich in humus are always superior in
quality, taste, and keeping power to those raised by other means. The
quality of wines, other things being equal, follows the same rule. Almost
every villager in countries like France appreciates these points and will
talk of them freely without the slightest prompting.
In the case of fodder a very interesting example of the relation between
soil fertility and quality has recently been investigated. This was
noticed in the meadows of La Crau between Salon and Aries in Provence.
Here the fields are irrigated with muddy water, containing finely divided
limestone drawn from the Durance, and manured mostly with farm-yard
manure. The soils are open and permeable, the land is well drained
naturally. All the factors on which soil fertility depends are present
together--an open soil with ample organic matter, ample moisture, and the
ideal climate for growth. Any grazier who saw these meadows for the first
time would at once be impressed by them: a walk through the fields at
hay-making would prepare him for the news that it pays the owners of
high-quality animals to obtain their roughage from this distant source.
Several cuts of hay are produced every year, which enjoy such a
reputation for quality that the bales are sent long distances by motor
lorry to the various racing stables of France and are even exported to
Newmarket. The small stomach of the racehorse needs the very best food
possible. This the meadows of La Crau help to produce.
The origin of these irrigated meadows would provide an interesting story.
Did they arise as the result of a set of permanent manurial experiments
on the Broadbalk model or through the work of some observant local
pioneer? I suspect the second alternative will be found to be nearer the
truth. A definite answer to this question is desirable because in a
recent discussion at Rothamsted, on the relation between a fertile soil
and high-quality produce, it was stated that no evidence of such a
connexion could be discovered in the literature. The farmers of Provence,
however, have supplied it and also a measure of quality in the shape of a
satisfactory price. For the present the only way of measuring quality
seems to be by selling it. It cannot be weighed and measured by the
methods of the laboratory. Nevertheless it exists: moreover it
constitutes a very important factor in agriculture. Apparently some of
the experiment stations have not yet come to grips with this factor: the
farmers have. The sooner therefore that effective liaison is established
between these two agencies the better.
The effect of soil fertility on live stock can be observed in the field.
As animals live on crops we should naturally expect the character of the
plant as regards nutrition to be passed on to stock. This is so. The
effect of a fertile soil can at once be seen in the condition of the
animals. This is perhaps most easily observed in the bullocks fattened on
some of the notable pastures in Great Britain. The animals show a
well-developed bloom, the coat and skin look and feel right, the eyes are
clear, bright, and lively. The posture of the animal betokens health and
well-being. It is not necessary to weigh or measure them. A glance on the
part of a successful grazier, or of a butcher accustomed to deal with
high-class animals, is sufficient to tell them whether all is well or
whether there is something wrong with the soil or the management of the
animals or both. The results of a fertile soil and proper methods of
management are measured by the prices these animals fetch in the market
and the standing of the farmer in these markets. It should be a
compulsory item in the training of agricultural investigators to
accompany some of the best of our English cattle from the pasture to the
market and watch what happens there. They would at once discover that the
most fertile pastures produce the best animals, that auctioneers and
buyers detect quality instantly, and that such animals find a ready sale
and command the best prices. The reputation of the pastures is finally
passed on to the butcher and to his clients.
Resistance to insect and fungous disease is also conferred by humus.
Perhaps the best examples of this are to be seen in the East. In India,
the crops grown on the highly fertile soils round the 500,000 villages
suffer remarkably little from pests. This subject is developed at length
in a future chapter when the retreat of the crop and of the animal before
the parasite is discussed.
Soil fertility not only influences crops and live stock but also the
fauna of the locality. This is perhaps most easily seen in the fish of
streams which flow through areas of widely differing degrees of
fertility. An example of such difference is referred to at the end of
Chapter V of Isaac Walton's COMPLEAT ANGLER the following words:
'And so I shall proceed next to tell you, it is certain, that certain
fields near Leominster, a town in Herefordshire, are observed to make
sheep that graze upon them more fat than the next, and also to bear finer
wool; that is to say, that in that year in which they feed in such a
particular pasture, they shall yield finer wool than they did that year
before they came to feed in it, and coarser again if they shall return to
their former pasture; and again return to a finer wool, being fed in the
fine wool ground. Which I tell you, that you may the better believe that
I am certain, if I catch a trout in one meadow he shall be white and
faint, and very likely to be lousy; and as certainly if I catch a trout
in the next meadow, he shall be strong and red and lusty and much better
meat: trust me, scholar. I have caught many a trout in a particular
meadow, that the very shape and enamelled colour of him hath been such as
hath joyed me to look on him: and I have then with much pleasure
concluded with Solomon, "Everything is beautiful in his season".'
Soil fertility is the condition which results from the operation of
Nature's round, from the orderly revolution of the wheel of life, from
the adoption and faithful execution of the first principle of
agriculture--there must always be a perfect balance between the processes
of growth and the processes of decay. The consequences of this condition
are a living soil, abundant crops of good quality, and live stock which
possess the bloom of health. The key to a fertile soil and a prosperous
agriculture is humus.
BIBLIOGRAPHY
RAYNER, M. C. Mycorrhiza: an Account of Non-pathogenic Infection
by Fungi in Vascular Plants and Bryophytes, London, 1927.
---------'Mycorrhiza in relation to Forestry', Forestry, viii,
1934, p. 96; x, 1936, p. 1; and xiii, 1939, p. 19.
WAKSMAN, S. A. Humus: Origin, Chemical Composition, and Importance
in Nature, London, 1938.
CHAPTER III
THE RESTORATION OF FERTILITY
The moment mankind undertook the business of raising crops and breeding
animals, the processes of Nature were subjected to interference. Soil
fertility was exploited for the growing of food and the production of the
raw materials--such as wool, skins, and vegetable fibres--needed for
clothing. Up to the dawn of the Industrial Revolution in the West, the
losses of humus involved in these agricultural operations were made up
either by the return of waste material to the soil or by taking up virgin
land.
Where the return of wastes balanced the losses of humus involved in
production, systems of agriculture became stabilized and there was no
loss of fertility. The example of China has already been quoted. The old
mixed farming of a large part of Europe, including Great
Britain--characterized by a correct balance between arable and live
stock, the conversion of wastes into farmyard manure, methods of sheep
folding, and the copious use of the temporary ley--is another instance of
the same thing.
The constant exploitation of new areas to replace worn-out land has also
gone on for centuries and is still taking place. Sometimes this has
involved wars and conquests: at other times nothing more than taking up
fresh prairie or forest land wherever this was to be found. A special
method is adopted by some primitive tribes. The forest growth is burnt
down, the store of humus is converted into crops, the exhausted land is
given back to Nature for reafforestation and the building up of a new
reserve of humus. In a rough and ready way fertility is maintained. Such
shifting cultivation still exists all over the world, but like the taking
up of new land is only possible when the population is small and suitable
land abundant. This burning process has even been incorporated into
permanent systems of agriculture and has proved of great value in rice
cultivation in western India. Here the intractable soils of the rice
nurseries have to be prepared during the last part of the hot season so
that the seedlings are ready for transplanting by the break of the
monsoon. This is achieved by covering the nurseries with branches
collected from the forest and setting fire to the mass. The heat destroys
the colloids, restores the tilth, and makes the manuring and cultivation
of the rice nurseries possible.
It is an easy matter to destroy a balanced agriculture. Once the demand
for food and raw materials increases and good prices are obtained for the
produce of the soil, the pressure on soil fertility becomes intense. The
temptation to convert this fertility into money becomes irresistible.
Western agriculture was subjected to this strain by the very rapid
developments which followed the invention of the steam-engine, the
internal combustion engine, electrically driven motors, and improvements
in communications and transport. Factory after factory arose; a demand
for labour followed; the urban population increased. All these
developments provided new and expanding markets for food and raw
materials. These were supplied in three ways--by cashing-in the existing
fertility of the whole world, by the use of a temporary substitute for
soil fertility in the shape of artificial manures, and by a combination
of both methods. The net result has been that agriculture has become
unbalanced and therefore unstable.
Let us review briefly the operations of Western agriculture from the
point of view of the utilization of wastes in order to discover whether
the gap between the losses and gains of humus, now bridged by
artificials, can be reduced or abolished altogether. If this is possible,
something can be done to restore the balance of agriculture and to make
it more stable and therefore more permanent.
Many sources of soil organic matter exist, namely: (1) the roots of
crops, weeds, and crop residues which are turned under in the course of
cultivation; (2) the algae met with in the surface soil; (3) temporary
leys, the turf of worn-out grass land, catch crops, and green-manures;
(4) the urine of animals; (5) farmyard manure; (6) the contents of the
dustbins of our cities and towns; (7) certain factory wastes which result
from the processing of agricultural produce; (8) the wastes of the urban
population; (9) water-weeds, including seaweed. These must now be very
briefly considered. In later chapters most of these matters will be
referred to again and discussed in greater detail.
THE RESIDUES TURNED UNDER IN THE COURSE OF CULTIVATION. It is not always
realized that about half of every crop--the root system--remains in the
ground at harvest time and thus provides a continuous return of organic
matter to the soil. The weeds and their roots ploughed in during the
ordinary course of cultivation add to this supply. When these residues,
supplemented by the fixation of nitrogen from the atmosphere, are
accompanied by skilful soil management, which safeguards the precious
store of humus, crop production can be maintained at a low level without
the addition of any manure whatsoever beyond the occasional droppings of
live stock and birds. A good example of such a system of farming without
manure is to be found in the alluvial soils of the United Provinces in
India where the field records of ten centuries prove that the land
produces small crops year after year without any falling off in
fertility. A perfect balance has been reached between the manurial
requirements of the crops harvested and the natural processes which
recuperate fertility. The greatest care, however, is taken not to
over-cultivate, not to cultivate at the wrong time, or to stimulate the
soil processes by chemical manures. Systems of farming such as these
supply as it were the base-line for agricultural development. A similar
though not so convincing result is provided by the permanent wheat plot
at Rothamsted, where this crop has been grown on the same land without
manure since 1844. This plot, which has been without manure of any kind
since 1839, showed a slow decline in production for the first eighteen
years, after which the yield has been practically constant. The reserves
of humus in this case left over from the days of mixed farming evidently
lasted for nearly twenty years. There are, however, two obvious
weaknesses in this experiment. This plot does not represent any system of
agriculture, it only speaks for itself. Nothing has been done to prevent
earthworms and other animals from bringing in a constant supply of
manure, in the shape of their wastes, from the surrounding land. It is
much too small to yield a significant result.
Soil algae are a much more important factor in the tropics than in
temperate regions. Nevertheless they occur in all soils and often play a
part in the maintenance of soil fertility. Towards the end of the rainy
season in countries like India a thick algal film occurs on the surface
of the soil which immobilizes a large amount of combined nitrogen
otherwise likely to be lost by leaching. While this film is forming
cultivation is suspended and weeds are allowed to grow. Just before the
sowing of the cold weather crops in October the land is thoroughly
cultivated, when this easily decomposable and finely divided organic
matter, which is rich in nitrogen, is transformed into humus and then
into nitrates. How far a similar method can be utilized in colder
countries is a matter for investigation. In the East cultivation always
fits in with the life-cycle in a remarkable way. In the West cultivation
is regarded as an end in itself and not, as it should be, as a factor in
the wheel of life. Europe has much to learn from Asia in the cultivation
of the soil.
TEMPORARY LEYS, CATCH-CROPS, GREEN-MANURES, AND THE TURF OF WORN-OUT
GRASS LAND are perhaps the most important source of humus in Western
agriculture. All these crops develop a large root system; the permanent
and temporary leys give rise to ample residues of organic matter which
accumulate in the surface soil. Green-manures and catch-crops develop a
certain amount of soft and easily decomposable tissue. Provided these
crops are properly utilized a large addition of new humus can be added to
the soil. The efficiency of these methods of maintaining soil fertility
could, however, be very greatly increased.
THE URINE OF ANIMALS. The key substance in the manufacture of humus from
vegetable wastes is urine--the drainage of the active cells and glands of
the animal. It contains in a soluble and balanced form all the nitrogen
and minerals, and in all probability the accessory growth-substances as
well, needed for the work of the fungi and bacteria which break down the
various forms of cellulose--the first step in the synthesis of humus. It
carries in all probability every raw material, known and unknown,
discovered and undiscovered, needed in the building up of a fertile soil.
Much of this vital substance for restoring soil fertility is either
wasted or only imperfectly utilized. This fact alone would explain the
disintegration of the agriculture of the West.
Although FARM-YARD MANURE has always been one of the principal means of
replenishing soil losses, even now the methods by which this substance is
prepared are nothing short of deplorable. The making of farm-yard manure
is the weakest link in the agriculture of Western countries. For
centuries this weakness has been the fundamental fault of Western
farming, one completely overlooked by many observers and the great
majority of investigators.
DUSTBIN REFUSE. Practically no agricultural use is now being made of the
impure cellulose and kitchen wastes which find their way into the urban
dustbin. These are mostly buried in controlled tips or burnt.
ANIMAL RESIDUES. A number of wastes connected with the processing of food
and some of the raw materials needed in industry are utilized on the land
and find a ready market. The animal residues include such materials as
dried blood, feathers, greaves, hair waste, hoof and horn, rabbit waste,
slaughter-house refuse, and fish waste. There is a brisk demand for most
of these substances, as they give good results on the land. The only
drawback is the limited supplies available. The organic residues from
manufacture consist of damaged oil-cakes, shoddy and tannery waste, of
which shoddy, a by-product of the wool industry, is the most important.
These two classes of wastes, animal and industrial, are applied to the
soil direct and, generally speaking, command much higher prices than
would be expected from their content of nitrogen, phosphorus, and potash.
This is because the soil is in such urgent need of humus and because the
supply falls so far short of the demand. It is probable that a better use
for these wastes will be found as raw materials for the compost heaps of
the future, where they will act as substitutes for urine in the breaking
down of dustbin refuse in localities where the supply of farm-yard manure
is restricted.
WATER WEEDS. Little use is made of water weeds in maintaining soil
fertility. Perhaps the most useful of these is seaweed, which is thrown
up on the beaches in large quantities at certain times of the year and
which contains iodine and includes the animal residues needed for
converting vegetable wastes into humus. Many of our sea-side resorts
could easily manufacture from seaweed and dustbin refuse the vast
quantities of humus needed for the farms and market gardens in their
neighbourhood and so balance the local agriculture. Little or nothing,
however, is being done in this direction. In some cases the seaweed
collection on pleasure beaches is taken up by the farmers with good
results, but the systematic utilization of seaweed in the compost heap is
still a matter for the future. The streams and rivers which carry off the
surplus rainfall also contain appreciable quantities of combined nitrogen
and minerals in solution. Much of this could be intercepted by the
cultivation of suitable plants on the borders of these streams which
would furnish large quantities of easily decomposable material for humus
manufacture.
THE NIGHT SOIL AND URINE of the population is at present almost
completely lost to the land. In urban areas the concentration of the
population is the main reason why water-borne sewage systems have
developed. The greatest difficulty in the path of the reformer is the
absence of sufficient land for dealing with these wastes. In country
districts, however, there are no insurmountable obstacles to the
utilization of human wastes.
It will be evident that in almost every case the vegetable and animal
residues of Western agriculture are either being completely wasted or
else imperfectly utilized. A wide gap between the humus used up in crop
production and the humus added as manure has naturally developed. This
has been filled by chemical manures. The principle followed, based on the
Liebig tradition, is that any deficiencies in the soil solution can be
made up by the addition of suitable chemicals. This is based on a
complete misconception of plant nutrition. It is superficial and
fundamentally unsound. It takes no account of the life of the soil,
including the mycorrhizal association--the living fungous bridge which
connects soil and sap. Artificial manures lead inevitably to artificial
nutrition, artificial food, artificial animals, and finally to artificial
men and women.
The ease with which crops can be grown with chemicals has made the
correct utilization of wastes much more difficult. If a cheap substitute
for humus exists why not use it? The answer is twofold. In the first
place, chemicals can never be a substitute for humus because Nature has
ordained that the soil must live and the mycorrhizal association must be
an essential link in plant nutrition. In the second place, the use of
such a substitute cannot be cheap because soil fertility--one of the most
important assets of any country--is lost; because artificial plants,
artificial animals, and artificial men are unhealthy and can only be
protected from the parasites, whose duty it is to remove them, by means
of poison sprays, vaccines and serums and an expensive system of patent
medicines, panel doctors, hospitals, and so forth. When the finance of
crop production is considered together with that of the various social
services which are needed to repair the consequences of an unsound
agriculture, and when it is borne in mind that our greatest possession is
a healthy, virile population, the cheapness of artificial manures
disappears altogether. In the years to come chemical manures will be
considered as one of the greatest follies of the industrial epoch. The
teachings of the agricultural economists of this period will be dismissed
as superficial.
In the next section of this book the methods by which the agriculture of
the West can be reformed and balanced and the use of artificial manures
given up will be discussed.
BIBLIOGRAPHY
CLARKE, G. 'Some Aspects of Soil Improvement in relation to Crop
Production' Proc. of the Seventeenth Indian Science Congress,
Asiatic Society of Bengal, Calcutta, 1930, p. 23
HALL, SIR A. DANIEL. The Improvement of Native Agriculture in relation to
Population and Public Health, Oxford University Press, 1936.
HOWARD, A., and WAD, Y. D. The Waste Products of Agriculture:
Their Utilization as Humus, Oxford University Press, 1931
MANN, H. H., JOSHI, N. V., and KANITICAR, N. V. 'The Rab System of Rice
Cultivation in Western India', Mem. of the Dept. of Agriculture in India
(Chemical Series), ii 1912, p. 141.
Manures and Manuring, Bulletin 36 of the Ministry of Agriculture
and Fisheries, H.M. Stationery Office, 1937.
PART II THE INDORE PROCESS
CHAPTER IV
THE INDORE PROCESS
The Indore Process for the manufacture of humus from vegetable and animal
wastes was devised at the Institute of Plant Industry, Indore, Central
India, between the years 1924 and 1931. It was named after the Indian
State in which it originated, in grateful remembrance of all the Indore
Darbar did to make my task in Central India easier and more pleasant.
Although the working out of the actual process only took seven years, the
foundations on which it is based occupied me for more than a quarter of a
century. Two independent lines of thought and study led up to the final
result. One of these concerns the nature of disease and is discussed more
fully in Chapter XI under the heading--'The Retreat of the Crop and the
Animal before the Parasite'. It was observed in the course of these
studies that the maintenance of soil fertility is the real basis of
health and of resistance to disease. The various parasites were found to
be only secondary matters: their activities resulted from the breakdown
of a complex biological system--the soil in its relation to the plant and
to the animal--due to improper methods of agriculture, an impoverished
soil, or to a combination of both.
The second line of thought arose in the course of nineteen years
(1905-24) spent in plant-breeding at Pusa, when it was gradually realized
that the full possibilities of the improvement of the variety can only be
achieved when the soil in which the new types are grown is provided with
an adequate supply of humus. Improved varieties by themselves could be
relied upon to give an increased yield in the neighbourhood of 10 per
cent.: improved varieties plus better soil conditions were found to
produce an increment up to 100 per cent. or even more. As an addition of
even 10 per cent. to the yield would ultimately impose a severe strain on
the frail fertility reserves of the soils of India and would gradually
lead to their impoverishment, plant-breeding to achieve any permanent
success would have to include a continuous addition to the humus content
of the small fields of the Indian cultivators. The real problem was not
the improvement of the variety but how simultaneously to make the variety
and the soil more efficient.
By about the year 1918 these two hitherto independent approaches to the
problems of crop production--by way of pathology and by way of
plant-breeding--began to coalesce. It became clearer and clearer that
agricultural research itself was involved in the problem; that the
organization was responsible for the failure to recognize the things that
matter in agriculture and would therefore have to be reformed; the
separation of work on crops into such compartments as plant-breeding,
mycology, entomology, and so forth, would have to be given up; the plant
would have to be studied in relation to the soil on the one hand and to
the agricultural practices of the locality on the other. An approach to
the problems of crop production on such a wide front was obviously
impossible in a research institute like Pusa in which the work on crops
was divided into no less than six separate sections. The working out of a
method of manufacturing humus from waste products and a study of the
reaction of the crop to improved soil conditions would encroach on the
work of practically every section of the Institute. As no progress has
ever been made in science without complete freedom, the only way of
studying soil fertility as one subject appeared to be to found a new
institute in which the plant would be the centre of the subject and where
science and practice could be brought to bear on the problem without any
consideration of the existing organization of agricultural research.
Thanks to the support of a group of Central Indian States and a large
grant from the Indian Central Cotton Committee, the Institute of Plant
Industry was founded at Indore in 1924. Central India was selected as the
home of this new research centre for two reasons: (1) the offer on a 99
years' lease of an area of 300 acres of suitable land by the Indore
Darbar, and (2) the absence in the Central India Agency of any organized
system of agricultural research such as had been established throughout
British India. This tract therefore provided the land on the one hand and
freedom from interference on the other for the working out of a new
approach, based on the humus content of the soil, to the problems
underlying crop production. (An account of the organization of the
Institute of Plant Industry was published as THE APPLICATION OF SCIENCE
TO CROP-PRODUCTION by the Oxford University Press in 1929.)
The work at Indore accomplished two things: (1) the obsolete character of
the present-day organization of agricultural research was demonstrated;
(2) a practical method of manufacturing humus was devised.
The Indore Process was first described in detail in 1931 in Chapter IV of
THE WASTE PRODUCTS OF AGRICULTURE. Since that date the method has been
taken up by most of the plantation industries and also on many farms and
gardens all over the world. In the course of this work nothing has been
added to the two main principles underlying the process, namely, (1) the
admixture of vegetable and animal wastes with a base for neutralizing
acidity, and (2) the management of the mass so that the micro-organisms
which do the work can function in the most effective manner. A number of
minor changes in working have, however, been suggested. Some of these
have proved advantageous in increasing the output. In the following
account the original description has been followed, but all useful
improvements have been incorporated: the technique has been brought up to
date.
THE RAW MATERIALS NEEDED
1. VEGETABLE WASTES. In temperate countries like Great Britain these
include--straw, chaff, damaged hay and clover, hedge and bank trimmings,
weeds including sea-and water-weeds, prunings, hop-vine and hop-string,
potato haulm, market-garden residues including those of the greenhouse,
bracken, fallen leaves, sawdust, and wood shavings. A limited amount of
other vegetable material like the husks of cotton seed, cacao, and ground
nuts as well as banana stalks are also available near some of the large
cities.
In the tropics and sub-tropics the vegetable wastes consist of very
similar materials including the vegetation of waste areas, grass, plants
grown for shade and green-manure, sugar-cane leaves and stumps, all crop
residues not consumed by live stock, cotton stalks, weeds, sawdust and
wood shavings, and plants grown for providing compostable material on the
borders of fields, roadsides, and any vacant corners available.
A continuous supply of mixed dry vegetable wastes throughout the year, in
a proper state of division, is the chief factor in the process. The ideal
chemical composition of these materials should be such that, after being
used as bedding for live stock, the carbon: nitrogen ratio is in the
neighbourhood of 33:1. The material should also be in such a physical
condition that the fungi and bacteria can obtain ready access to and
break down the tissues without delay. The bark, which is the natural
protection of the celluloses and lignins against the inroads of fungi,
must first be destroyed. This is the reason why all woody materials--such
as cotton and pigeon-pea stalks--were always laid on the roads at Indore
and crushed by the traffic into a fine state of division before
composting.
All over the world one of the first objections to the adoption of the
Indore Process is that there is nothing worth composting or only small
supplies of such material. In practically all such cases any shortage of
wastes has soon been met by a more effective use of the land and by
actually growing plants for composting on every possible square foot of
soil. If Nature's way of using sunlight to the full in the virgin forest
is compared with that on the average farm or on the average tea and
rubber estate, it will be seen what leeway can be made up in growing
suitable material for making humus. Sometimes the objection is heard that
all this will cost too much. The answer is provided by the dust-bowls of
North America. The soil must have its manurial rights or farming dies.
2. ANIMAL RESIDUES. The animal residues ordinarily available all over the
world are much the same--the urine and dung of live stock, the droppings
of poultry, kitchen waste including bones. Where no live stock is kept
and animal residues are not available, substitutes such as dried blood,
slaughter-house refuse, powdered hoof and horn, fish manure, and so forth
can be employed. The waste products of the animal in some form or another
are essential if real humus is to be made for the two following reasons.
(a) The verdict given by mother earth between humus made with animal
residues and humus made with chemical activators like calcium cyanamide
and the various salts of ammonia has always been in favour of the former.
One has only to feel and smell a handful of compost made by these two
methods to understand the plant's preference for humus made with animal
residues. The one is soft to the feel with the smell of rich woodland
earth: the other is often harsh to the touch with a sour odour. Sometimes
when the two samples of humus made from similar vegetable wastes are
analysed, the better report is obtained by the compost made with chemical
activators. When, however, they are applied to the soil the plant
speedily reverses the verdict of the laboratory. Dr. Rayner refers to
this conflict between mother earth and the analyst, in the case of some
composts suitable for forestry nurseries, in the following words:
'Full chemical analyses are now available for a number of these composts,
and it is not without interest to recall that in the initial stages of
the work a competent critic reported on one of them--since proved to be
among the most effective a basis of comparative analysis, as "an organic
manure of comparatively little value"; while another--since proved least
successful of all those tested--was approved as a "first-class organic
manure".'
The activator used in the first case was dried blood, in the second case
an ammonium salt.
(b) No permanent or effective system of agriculture has ever been devised
without the animal. Many attempts have been made, but sooner or later
they break down. The replacement of live stock by artificials is always
followed by disease the moment the original store of soil fertility is
exhausted.
Where live stock is maintained the collection of their waste
products--urine and dung--in the most effective manner is important.
At Indore the work-cattle were kept in well-ventilated sheds with earthen
floors and were bedded down daily with mixed vegetable wastes including
about 5 per cent. by volume of hard resistant material such as wood
shavings and sawdust. The cattle slept on this bedding during the night
when it was still further broken up and impregnated with urine. Next
morning the soiled bedding and cattle dung were removed to the pits for
composting; the earthen floor was then swept clean and all wet places
were covered with new earth, after scraping out the very wet patches. In
this way all the urine of the animals was absorbed; all smell in the
cattle sheds was avoided, and the breeding of flies in the earth
underneath the animals was entirely prevented. A new layer of bedding for
the next day was then laid.
Every three months the earth under the cattle was changed, the
urine-impregnated soil was broken up in a mortar mill and stored under
cover near the compost pits. This urine earth, mixed with any wood ashes
available, served as a combined activator and base in composting.
In the tropics, where there is abundance of labour, no difficulty will be
experienced in copying the Indore plan. All the urine can be absorbed:
all the soiled bedding can be used in the compost pits every morning.
In countries like Great Britain and North America, where labour is both
scarce and dear, objection will at once be raised to the Indore plan.
Concrete or pitched floors are here the rule. The valuable urine and dung
are often removed to the drains by a water spray. In such cases, however,
the indispensable urine could either be absorbed on the floors themselves
by the addition to the bedding of substances like peat and sawdust mixed
with a little earth, or the urine could be directed into small bricked
pits just outside the building, filled with any suitable absorbent which
is periodically removed and renewed. In this way liquid manure tanks can
be avoided. At all costs the urine must be used for composting.
3. BASES FOR NEUTRALIZING EXCESSIVE ACIDITY. In the manufacture of humus
the fermenting mixture soon becomes acid in reaction. This acidity must
be neutralized, otherwise the work of the microorganisms cannot proceed
at the requisite speed. A base is therefore necessary. Where the
carbonates of calcium or potassium are available in the form of powdered
chalk or limestone, or wood ashes, these materials either alone,
together, or mixed with earth, provide a convenient base for maintaining
the general reaction within the optimum range (pH 7.0 to 8.0) needed by
the microorganisms which break down cellulose. Where wood ashes,
limestone, or chalk are not available, earth can be used by itself.
Slaked lime can also be employed, but it is not so suitable as the
carbonate. Quicklime is much too fierce a base.
4. WATER AND AIR. Water is needed during the whole of the period during
which humus is being made. Abundant aeration is also essential during the
early stages. If too much water is used the aeration of the mass is
impeded, the fermentation stops and may soon become anaerobic too soon.
If too little water is employed the activities of the micro-organisms
slow down and then cease. The ideal condition is for the moisture content
of the mass to be maintained at about half saturation during the early
stages, as near as possible to the condition of a pressed-out sponge.
Simple as all this sounds, it is by no means easy in practice
simultaneously to maintain the moisture content and the aeration of a
compost heap so that the micro-organisms can carry out their work
effectively. The tendency almost everywhere is to get the mass too
sodden.
The simplest and most effective method of providing water and oxygen
together is whenever possible to use the rainfall--which is a saturated
solution of oxygen--and always to keep the fermenting mass open at the
beginning so that atmospheric air can enter and the carbon dioxide
produced can escape.
After the preliminary fungous stage is completed and the vegetable wastes
have broken down sufficiently to be dealt with by bacteria, the synthesis
of humus proceeds under anaerobic conditions when no special measures for
the aeration of the dense mass are either possible or necessary.
PITS VERSUS HEAPS
Two methods of converting the above wastes into humus are in common use.
Pits or heaps can be employed.
Where the fermenting mass is liable to dry out or to cool very rapidly,
the manufacture should take place in shallow pits. A considerable saving
of water then results. The temperature of the mass tends to remain high
and uniform. Sometimes, however, composting in pits is disadvantageous on
account of water-logging by storm water, by heavy rain, and by the rise
of the ground-water from below. All these result in a wet sodden mass in
which an adequate supply of air is out of the question. To obviate such
water-logging the composting pits are: (1) surrounded by a catch-drain to
cut off surface water; (2) protected by a thatched roof where the
rainfall is high and heavy bursts of monsoon rain are the rule; or (3)
provided with soakaways at suitable points combined with a slight slope
of the floors of the pit towards the drainage corner. Where there is a
pronounced rise in the water-table during the rainy season, care must be
taken, in siting the pits, that they are so placed that there is no
invasion of water from below.
To save the expense of digging pits and to use up sites where excavation
is out of the question, composting in heaps is practiced. A great deal
can be done to increase the efficiency of the heap by protecting the
composting area from storm water by means of catch-drains and by suitable
shelter from wind, which often prevents all fermentation on the more
exposed sides of the heap. In temperate climates heaps should always face
the south, and wherever possible should be made in front of a south wall
and be protected from wind on the east and west. The effect of heavy rain
in slowing down fermentation can be reduced by increasing the size of the
heap as much as possible. Large heaps always do better than small ones.
In localities of high monsoon rainfall like Assam and Ceylon, there is a
definite tendency to provide the heap or the pit with a grass roof so
that the fermentation can proceed at an even rate and so that the annual
output is not interfered with by temporary water-logging. After a year or
two of service the roof itself is composted. In Great Britain thatched
hurdles can be used.
CHARGING THE HEAPS OR PITS
A convenient size for the compost pits (where the annual output is in the
neighbourhood of 1,000 tons) is 30 feet by 14 feet and 3 feet deep with
sloping sides. The depth is the most important dimension on account of
the aeration factor. Air percolates the fermenting mass to a depth of
about 18 to 24 inches only, so for a height of 36 inches extra aeration
must be provided. This is arranged by means of vertical vents, every 4
feet, made by a light crowbar as each section of the pit is charged.
Charging a pit 30 feet long takes place in six sections each 5 feet wide.
The first section, however, is left vacant to allow of the contents being
turned. The second section is first charged. A layer of vegetable wastes
about 6 inches deep is laid across the pit to a width of 5 feet. This is
followed by a layer of soiled bedding or farm-yard manure 2 inches in
thickness. The layer of manure is then well sprinkled with a mixture of
urine earth and wood ashes or with earth alone, care being taken not to
add more than a thin film of about one-eighth of an inch in thickness. If
too much is added aeration will be impeded. The sandwich is then watered
where necessary with a hose fitted with a rose for breaking up the spray.
The charging and watering process is then continued as before until the
total height of the section reaches 5 feet. Three vertical aeration
vents, about 4 inches in diameter, are then made in the mass by working a
crowbar from side to side. The first vent is in the centre, the other two
midway between the centre and the sides. As the pit is 14 feet wide and
there are three vents, these will be 3 feet 6 inches apart. The next
section of the pit (5 feet wide) is then built up close to the first and
watered as before. When five sections are completed the pit is filled.
The advantages of filling a pit or making a heap in sections to the full
height of 5 feet are: (1) fermentation begins at once in each section and
no time is lost; (2) no trampling of the mass takes place; (3) aeration
vents can be made in each completed section without standing on the
mixture.
In dry climates each day's contribution to the pit should again be
lightly watered in the evening and the watering repeated the next
morning. In this way the first watering at the time of charge is added in
three portions--one at the actual time of charging, in the evening after
charging is completed and again the next morning after an interval of
twelve hours. The object of this procedure is to give the mass the
necessary time to absorb the water.
The total amount of water that should be added at the beginning of
fermentation depends on the nature of the material, on the climate and on
the rainfall. Watering as a rule is unnecessary in Great Britain. If the
material contains about a quarter by volume of fresh greenstuff the
amount of water needed can be considerably reduced. In rainy weather when
everything is on the damp side no water at all is needed. Correct
watering is a matter of local circumstances and of individual judgement.
At no period should the mass be wet: at no period should the pit be
allowed to dry out completely. At the Iceni Nurseries in South
Lincolnshire in Great Britain, where the annual rainfall is about 24
inches and a good deal of fresh green market-garden refuse is composted,
watering the heaps at all stages is unnecessary. At Indore in Central
India where the rainfall was about 50 inches, which fell in about four
months, watering was always essential except during the actual rainy
season. These two examples prove that no general rule can ever be laid
down as to the amount of water to be added in composting. The amount
depends on circumstances. The water needed at Indore was from 200 to 300
gallons for each cubic yard of finished humus.
As each section of the pit is completed, everything is ready for the
development of an active fungous growth, the first stage in the
manufacture of humus. It is essential to initiate this growth as quickly
as possible and then to maintain it. As a rule it is well established by
the second or third day after charging. Soon after the first appearance
of fungous growth the mass begins to shrink and in a few days will just
fill the pit, the depth being reduced to about 36 inches.
Two things must be carefully watched for and prevented during the first
phase: (1) the establishment of anaerobic conditions caused generally by
over-watering or by want of attention to the details of charging; it is
at once indicated by smell and by the appearance of flies attempting to
breed in the mass; when this occurs the pit should be turned at once; (2)
fermentation may slow down for want of water. In such cases the mass
should be watered. Experience will soon teach what amount of water is
needed at the time of charge.
TURNING THE COMPOST
To ensure uniform mixture and decay and to provide the necessary amount
of water and air for the completion of the aerobic phase it is necessary
to turn the material twice.
FIRST TURN. The first turn should take place between 2 and 3 weeks after
charging. The vacant space, about 5 feet wide, at the end of the pit
allows the mass to be conveniently turned from one end by means of a
pitchfork. The fermenting material is piled up loosely against the vacant
end of the pit, care being taken to turn the unaltered layer in contact
with the air into the middle of the new heap. As the turning takes place,
the mass is watered, if necessary, as at the time of charging, care being
taken to make the material moist but not sodden with water. The aim
should be to provide the mass with sufficient moisture to carry on the
fermentation to the second turn. To achieve this sufficient time must be
given for the absorption of water. The best way is to proceed as at the
time of charging and add any water needed in two stages--as the turning
is being done and again next morning. Another series of vertical air
vents 3 feet 6 inches apart should be made with a crowbar as the new heap
is being made.
SECOND TURN. About five weeks after charge the material is turned a
second time but in the reverse direction. By this time the fungous stage
will be almost over, the mass will be darkening in colour and the
material will be showing marked signs of breaking down. From now onwards
bacteria take an increasing share in humus manufacture and the process
becomes anaerobic. The second turn is a convenient opportunity for
supplying sufficient water for completing the fermentation. This should
be added during the actual turning and again the next morning to bring
the moisture content to the ideal condition--that of a pressed-out
sponge. It will be observed as manufacture proceeds that the mass
crumbles and that less and less difficulty occurs in keeping the material
moist. This is due to two things: (1) less water is needed in the
fermentation; (2) the absorptive and water-holding power of the mass
rapidly increase as the stage of finished humus is approached.
Soon after the second turn the ripening process begins. It is during this
period that the fixation of atmospheric nitrogen takes place. Under
favourable circumstances as much as 25 per cent. Of additional free
nitrogen may be secured from the atmosphere.
The activity of the various micro-organisms which synthesize humus can
most easily be followed from the temperature records. A very high
temperature, about 65 degrees C. (149 degrees F.), is established at the
outset, which continues with a moderate downward gradient to 30 degrees
C. (86 degrees F.) at the end of ninety days. This range fits in well
with the optimum temperature conditions required for the micro-organisms
which break down cellulose. The aerobic thermophyllic bacteria thrive best
between 40 degrees C. (104 degrees F.) and 55 degrees C.
(131 degrees F.). Before each turn, a definite slowing down in the
fermentation takes place: this is accompanied by a fall in temperature.
As soon as the mass is re-made, when more thorough admixture with copious
aeration occurs, there is a renewal of activity during which the
undecomposed portion of the vegetable matter from the outside of the heap
or pit is attacked. This activity is followed by a distinct rise in
temperature.
THE STORAGE OF HUMUS
Three months after charge the micro-organisms will have fulfilled their
task and humus will have been completely synthesized. It is now ready for
the land. If kept in heaps after ripening is completed, a loss in
efficiency must be faced. The oxidation processes will continue.
Nitrification will begin, resulting in the formation of soluble nitrates.
These may be lost either by leaching during heavy rain or they will
furnish the anaerobic organisms with just the material they need for
their oxygen supply. Such losses do not occur to anything like the same
extent when the humus is banked by adding it to the soil. Freshly
prepared humus is perhaps the farmer's chief asset and must therefore be
looked after as if it were actual money. It is also an important section
of the live stock of the farm. Although this live stock can only be seen
under the microscope, it requires just as much thought and care as the
pigs which can be seen with the naked eye. If humus must be stored it
should be kept under cover and turned from time to time.
OUTPUT
The output of compost per annum obviously depends on circumstances. At
the Institute of Plant Industry, Indore, where the supply of urine and
dung was always greater than that of vegetable waste, fifty cartloads
(each 27 c. ft.) of ripe compost, i.e. 1,350 cubic feet or 50 cubic
yards, could be prepared from one pair of oxen. Had sufficient vegetable
wastes been available the quantity could have been at least doubled. The
work-cattle at Indore were of the Malvi breed, about three-quarters the
size of the average milking-cow of countries like Great Britain. The
urine and dung of an average English cow or bullock, therefore, if
properly composted with ample wastes would produce about sixty cartloads
of humus a year, equivalent to about 1,600 cubic feet or 60 cubic yards.
As the moisture content of humus varies from 30 to 60 per cent. during
the year, it is impossible to record the output in tons unless the
percentage of water is determined. The difficulty can be overcome by
expressing the output in cubic feet or cubic yards. The rate of
application per acre should also be stated as so many cubic feet or cubic
yards.
In devising the Indore Process the fullest use was made of agricultural
experience including that of the past. After the methods of Nature, as
seen in the forest, the practices which throw most light on the
preparation of humus are those of the Orient, which have been described
by King in FARMERS OF FORTY CENTURIES. In China a nation of observant
peasants has worked out for itself simple methods of returning to the
soil all the vegetable, animal, and human wastes that are available: a
dense population has been maintained without any falling off in
fertility.
Coming to the more purely laboratory investigations on the production of
humus, two proved of great value in perfecting the Indore Process: (1)
the papers of Waksman in which the supreme importance of micro-organisms
in the formation of humus was consistently stressed, and (2) the work of
H. B. Hutchinson and E. H. Richards on artificial farm-yard manure.
Waksman's insistence on the role of micro-organisms in the formation of
humus as well as on the paramount importance of the correct composition
of the wastes to be converted has done much to lift the subject from a
morass of chemical detail and empiricism on to the broad plane of biology
to which it rightly belongs. Once it was realized that composting
depended on the work of fungi and bacteria, the reform of the various
composting systems which are to be found all over the world could be
taken in hand. The essence of humus manufacture is first to provide the
organisms with the correct raw material and then to ensure that they have
suitable working conditions. Hutchinson and Richards come nearest to the
Indore Process but two fatal mistakes were made: (1) the use of chemicals
instead of urine as an activator in breaking down vegetable wastes, and
(2) the patenting of the ADCO process. Urine consists of the drainage of
every cell and every gland of the animal body and contains not only the
nitrogen and minerals needed by the fungi and bacteria which break down
cellulose, but all the accessory growth substances as well. The ADCO
powders merely supply factory-made chemicals as well as lime--a far
inferior base to the wood ashes and soil used in the Indore Process. It
focuses attention on yield rather than on quality. It introduces into
composting the same fundamental mistake that is being made in farming,
namely, the use of chemicals instead of natural manure. Further, the
patenting of a process (even when, as in this case, the patentees derive
no personal profit) always places the investigator in bondage; he becomes
the slave to his own scheme; rigidity takes the place of flexibility;
progress then becomes difficult, or even impossible. The ADCO