The Waste Products of Agriculture -- Their Utilization as Humus

by Albert Howard and Yeshwant D. Wad

Chapter 1

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 considering how the ideal method of manuring and of soil management can be devised, the first step is to bring under review the various systems of agriculture which so far have been evolved. These fall for the most part into two main groups: (1) the methods of the Occident to which a large amount of scientific attention has been devoted during the last fifty years; and (2) the practices of the Orient which have been almost unaffected by western science. (In the general organization of agriculture, Europe stands mid-way between the east and the west and provides, as it were, the connecting link between these two methods of farming.) The systems of agriculture of the Occident and of the Orient will now be briefly considered with a view of extracting from each ideas and results which can be utilized in the evolution of the ideal method of maintaining and increasing the fertility of the soil.

The Agricultural Systems of the Occident

The most striking characteristic of the agriculture of the west is the comparatively large size of the holding. Large farms are the rule; small holdings are the exception. (The growth of allotments for the production of vegetables in the neighbourhood of urban areas is a comparatively recent phenomenon and only affects a small area.)

The large farms of the west are for the most part engaged in the production of food and a few raw materials like wool for the urban populations of the world, which are mainly concerned with manufacture and trade. To produce these vast supplies, and at the same time to place them on the markets at low rates, practically all the unoccupied temperate regions of the world, which are suitable for the white races, have already been utilized. The best areas of North America, of the Argentine, of South Africa and large tracts of Australia and practically the whole of New Zealand have during the last hundred years been exploited to produce the endless procession of cargoes of food and raw materials required by the great markets of the world.

The weakness of this system of agriculture lies in the fact that it is new and has not yet received the support which centuries of successful experience alone can provide. At first it was based on the exploitation of the stores of organic matter accumulated by virgin land, which at the best could not last for more than a limited number of years. Even now there is practically no attempt to utilize the large quantities of wheat straw and other vegetable wastes for keeping up the store of organic matter in the soil. The new areas of North America for example soon showed signs of exhaustion. Manuring has become necessary as in the case of the older fields of Europe. To supply the large quantities of combined nitrogen needed, all possible sources except the right one -- the systematic conversion of the waste products of agriculture into humus -- have one after the other been utilized: guano from the islands off the Peruvian coast, nitrate of soda from Chile, sulphate of ammonia from coal and more recently synthetic nitrogen compounds obtained from the atmosphere. These substances are supplemented by another class of nitrogenous organic manures such as artificial guanos, dried blood and slaughter-house residues, oil cakes and wool waste -- the by-products of agriculture -- and by another group of artificials -- the various phosphatic and potassic fertilizers. These supplies of concentrated manures have enabled agricultural production to be kept at a high level. The fact of their existence for a time tended to distract attention from the fullest utilization of the by-products of the farm. Recently, however, a change has taken place and a large amount of scientific effort has been devoted to the problems which centre round the waste products, both animal and vegetable, of agriculture itself. The need of keeping up the supply of organic matter in the soil is now widely recognized.

After the large size of the holding and the necessity of manuring, the high cost of labour is another leading characteristic of western farming. The number of men per square mile of agricultural land who actually work is low. (The comparative figures of crop production per worker for the five-year period preceding the War, prepared by the United States Department of Agriculture, are instructive. The number of workers employed per 1,000 acres of crop land was approximately 235 in Italy, 160 in Germany, 120 in France, 105 in England and Wales, 60 in Scotland but only 41 in the United States. In Canada, according to Riddell, the 1911 figures show that every 1,000 acres called for only 26 workers. This observer states that in the three prairie provinces [Alberta, Manitoba, Saskatchewan] the figures are even more striking: the area under field crops was 17,677,091 acres, and the numbers engaged in agriculture was 283,472, so that each person so employed was responsible for 62 acres. Every 1,000 acres required only 16 workers. Since these data were published, further statements have appeared from which it would seem that the size of the working population in agriculture in North America has shrunk still further.) This state of things has arisen from the dearness and scarcity of labour, which has naturally led to the study of labour-saving devices including the use of machinery. Whenever a machine can be invented which saves human labour its spread is rapid. Engines of various kinds are the rule everywhere. The inevitable march of the combine-harvester, in all the wheat-producing areas of the world, is the latest example of the mechanization of the agriculture of the west.

Another feature of this extensive system of large-scale agriculture is the development of food preservation processes, of transport and of marketing, by which the products of agriculture are cheaply and rapidly moved from the field to the centres of distribution and consumption. There is no great dearth of capital at any stage. Money can always be found for any new machine and for any new development which is likely to return a dividend. Land and capital are abundant; efficient transport and good markets abound. The comparatively small supply of suitable labour and its high cost provide the chief agricultural problems of the west.

This system of agriculture is essentially modern and has developed largely as one of the consequences of the discovery of the steam engine and the rapid exploitation of the supplies of coal, oil and water-power. It has only been made possible by the existence of vast areas of virgin land in parts of the earth's surface on which the white races can live and work. As already mentioned the weak point in this method of crop production is that it is new and lacks the backing which only a long period of practical experience can supply. Mother Earth is provided with an abundant store of reserve fertility which can always be exploited for a time. Every really successful system of agriculture however must be based on the long view, otherwise the day of reckoning is certain.

Side by side with this method of utilizing the land there has been a great development of 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 printed results and advice to the farmer. At first the scientific workers naturally devoted themselves to solving local problems and to furnishing scientific explanations of various agricultural practices. This phase is now passing. A new note is beginning to appear in the publications of the experiment stations, namely that of direction and advice which can only be advanced by men whose education and training combine the ideas of science with the aims of the statesman. The feeling is not only growing but is being expressed that it is no longer the business of science merely to solve the problems of the moment. Something more is needed. The chief function of science in the agriculture of the future is to provide intelligent direction in general policy and to point the way.

The Agricultural Systems of the Orient

Peasant Holdings

The chief feature of the agricultural systems of the east is the small size of the holding. The relation between man-power and cultivated area in India is given in Table I. In this table, based on the Census Report of 1921, the number of workers and the acreage cultivated have been calculated for the chief provinces of British India. Incidentally these figures illustrate how intense is the struggle for existence in this portion of the tropics.

Table I.
The Relation between Man-power and Cultivated Area in India
Number of acres cultivated by 100 ordinary cultivators
North-West Frontier Province
Central Provinces
Bihar and Orissa
United Provinces

These minute holdings are frequently cultivated by extensive methods (those suitable for large areas) which neither utilize the full energies of man and beast nor the potential fertility of the soil. Such a system of agriculture can only result in poverty. The obvious line of advance is the gradual introduction of more intensive methods, for which the supply of suitable manure, within the means of the average cultivator, is bound to prove an important factor.

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 46,977,003, 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. (These figures agree very closely with those quoted in the Japan Year Book of 1931 in which the number of persons per square kilometre is given as 969: equivalent to 2,433 to the square mile.) 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. Although no accurate statistics are available in China, the examples quoted by King reveal a condition of affairs not unlike 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 farm 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.

The problems of tropical agriculture for the most part relate to small holdings. The main purpose of this peasant agriculture is crop production; animal husbandry is much less important. In India the crops grown fall into two classes -- (1) food and fodder crops and (2) money crops. The former includes, in order of area: rice, millets, wheat, pulses and fodder crops, barley and maize and sugar-cane. The money crops are more varied; cotton and oil seeds are the most important, followed by jute and other fibres, tobacco, tea, opium, indigo and coffee. It will be seen that food and fodder crops comprise 82 per cent of the total area under crops and that money crops, as far as extent is concerned, are relatively unimportant.

Table II.
Agricultural Statistics of British India, 1926-27
Area, in acres, under food and fodder crops
Pulses and other good grains
Fodder crops
Condiments, spices, fruits, vegetables, and misc. food crops
Total, food and fodder crops
Area, in acres, under money crops
Oil seeds, chiefly rape and mustard, sesamum, groundnuts and linseed
Jute and other fibres
Dyes, tanning materials, drugs, narcotics and miscellaneous crops
Total, money crops

The primary function of Indian agriculture is to supply the cultivator and his cattle with food. Compared with this duty all other matters are subsidiary. The houses are built of mud, thatched with grass and are almost devoid of furniture. Expenditure on clothing and warmth is, on account of the customs of the country and the nature of the climate, much smaller than in European countries. Nevertheless, the cultivators require a little money with which to pay the land revenue and to purchase a few necessaries in the village markets. Hence the growth of money crops to the extent of about one-fifth the total cultivated area. (See Table III below.) The produce, after conversion into cash, is afterwards either worked up in the local mills or exported. To some extent food crops are also money crops. The population of the towns and cities is largely fed from the produce of the soil, while in addition a small percentage of the total food grains produced is exported to foreign countries. In some crops like sugar-cane, the total out-turn is insufficient for the towns and large quantities of sugar are imported from Java, Mauritius and the continent of Europe.

Table III.
Yield of the More Important Crops of India, 1926-27
Food crops
29,636,000 tons
Money crops
12,132,000 bales (each 400 lb.)
4,960,000 (each 400 lb.)
2,035,000 tons.
Rape and mustard
986,000 tons.
407,000 tons.
411,000 tons.
Castor seed
128,000 tons.
392,917,800 lb.
34,286,806 lb.
23,002,700 lb.
18,100 cwt.

When we come to the details of soil management, a further striking difference between the methods in vogue in the west and on the peasant holdings of the east is at once manifest. In China, fertility has for centuries been maintained at a high level without the importation of artificial manures. 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, nevertheless 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. Moreover, on the alluvium of the Indo-Gangetic Plain, the deep, spreading root-system of the pigeon pea (Cajanus indicus Spreng.) is utilized by the peasantry as an efficient substitute for the periodical subsoil ploughing which these closely-packed, silt-like soils require. In the case of the best cultivators, the general soil management and particularly the conservation and utilization of combined nitrogen has already reached a high level. This has been described, in the case of the United Provinces of India, by Clarke in a recent paper which has been reproduced as Appendix B. In China and Japan not only the method of soil management but also the great attention that is paid to the systematic preparation, outside the field, of food materials for the crop from all kinds of vegetable and animal wastes compelled the admiration of one of the most brilliant of the agricultural investigators of the last generation. The results are set out by King in his unfinished work -- Farmers of Forty Centuries -- which should be prescribed as a textbook in every agricultural school and college in the world.

Another feature of this agriculture is the cultivation of rice wherever the soil and water-supply permit. In the scientific consideration of the methods of soil management under which the rice crop of the Orient is produced, practical experience at first seems 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. Nearly 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 calls for early investigation.)

Another important difference between the east and the west concerns the supply of labour. In the Orient it is everywhere adequate, as would naturally follow from the great density of the rural population. Indeed in India it is so abundant that if the time wasted by the cultivators and their cattle for a single year could be calculated as money, at the local rates of labour, a perfectly colossal figure would be obtained. One of the problems underlying the development of agriculture in India is the discovery of the best means of utilizing this constant drain, in the shape of wasted hours, for increasing crop production. There is therefore no lack of human labour in developing the agriculture of the east. Another favourable factor is the existence of excellent breeds of work-cattle and of the buffalo. (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 digestive processes of the buffalo is a subject which appears to have escaped the attention of the investigators of animal nutrition.)

The last characteristic of this ancient system of agriculture is lack of money. Again there is a great contrast between the east and the west. There is little or no spare capital for the improvement of the holding. Over large tracts of India at any rate, the cultivators are in the hands of the moneylender and indebtedness is the rule. For many years one of the pre-occupations of Government has been the discovery of safeguards by which the cultivator can be saved from the worst consequences of his own folly -- reckless borrowing for unproductive purposes -- and maintained on the land. The recent development of co-operation and the rapid increase in the number of primary credit societies has only been possible because of this volume of indebtedness.


While small holdings, accompanied by a dense population, are an important feature of eastern agriculture, nevertheless there are exceptions. Throughout this portion of the tropics European enterprise has removed the original forest and established in its place extensive plantations of such crops as sugar-cane, tea, rubber and coffee. The labour for these estates is obtained from indigenous sources; the capital and management are contributed by Europeans. Plantations of this kind are common all over the east and are an important feature of the agriculture of Java, Ceylon, the Federated Malay States, Assam and the uplands of Southern India. One of the features of this agriculture is the attention paid to manurial problems. Comparatively large sums of money are expended every year in the purchase of artificial manures, mainly for keeping up the supply of combined nitrogen. During a tour in Ceylon in 1908, when visits were paid by the senior author to a number of tea estates, the managers invariably produced their manurial programme on which suggestions were always invited. Ceylon at that time offered a tragic example of the damage which results from uncontrolled tropical rainfall on sloping land, from which the forest canopy had been removed without providing a proper system of terracing combined with surface-drainage. Over large areas of hilly country, formerly forest and now exclusively under tea, practically the whole of the valuable surface soil rich in humus had been lost by denudation. The tea plant was producing crops from the relatively poor subsoil, supplemented by the constant application of expensive manures.

In a recent review of this question in Crop Production in India published in 1924, the damage which has resulted from erosion on the plantations of the Orient was referred to (pp. 14-5) as follows:

Undeveloped Areas

Very large stretches of the Orient are still under forest and at present carry a very small population, supported by hunting, fishing and by the small cultivated areas surrounding the villages. These undeveloped forest areas occur everywhere, particularly in the Malay Archipelago, the Federated Malay States, Burma and the low country of Ceylon. In the search for the ideal method of manuring in the tropics, the greatest care will have to be taken to preserve the valuable surface soil whenever the forest canopy has to be removed for the creation of new cultivated land. Some at any rate of these potentially rich tracts are almost certain to be taken up during the present century. They will therefore provide ample opportunities of applying any lessons in soil management, which science can extract from experiment and from experience. The serious mistakes of the past must not be repeated when the time comes for developing the vast areas of tropical forest still untouched.

It will be evident that the systems of agriculture of the west and of the east are very different and that the two have little or nothing in common. In a sense these two methods of managing land remind one of the two sides of a coin. The one supplements the other: each can be regarded as a part of one great whole. Clearly when attempting to evolve the ideal system of manuring and soil management of the future, both of these widely different methods of agriculture must be studied. This has been done by the senior author for the last twenty-six years in various parts of India -- on the alluvium of the Indo-Gangetic plain at Pusa in Bihar, on the loess soils of the Quetta Valley on the Western Frontier and on the black cotton soils of peninsular India at Indore. The chief climatic factors at Indore are represented in Plate II. The climate of Quetta resembles generally that of Persia, where the rainfall is received mainly during the winter months, often in the form of snow. At these three centres a method of utilizing all the vegetable and animal wastes of the holding has gradually been evolved. The latest scientific work of the Occident and particularly that recently accomplished at the experiment station of New Jersey, together with the practices in vogue in India and the Far East, have been welded together and synthesized into a system for the continuous manufacture of manure throughout the year so that it forms an integral part of the industry of agriculture.

Plate I. Rainfall, temperature, humidity and drainage, Pusa, 1922.

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Plate II. Rainfall, ground-water level, temperature and humidity, Indore, Central India, 1928.

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(In considering all this information -- the various agricultural systems in use at the present time, as well as the large volume of scientific papers dealing with manurial questions, which have been poured out by the experiment stations during the last fifty years, we have been impressed by the evils inseparable from the present fragmentation of any large agricultural problem and its attack by way of the separate science. All this seems to follow from the excessive specialization which is now taking place, both in the teaching and in the application of science. In the training given to the students and in much of the published work, the tendency of knowing more and more about less and less is every year becoming more marked. For this reason any review of the problem of increasing soil fertility is rendered peculiarly difficult, not only by the vast mass of published papers but also by their fragmentary and piecemeal nature.)

No extra labour is required in our manure factory. No imported chemicals such as Adco are needed in this process. No capital is required at any stage of the manufacture. The methods now in use at Indore form the main subject of this book, which also attempts to deal with a number of related matters such as -- the role of organic matter in the soil, the methods of replenishing the supply of organic matter now in use and the recent investigations which have been carried out on the conditions necessary for converting raw organic residues into humus which can be immediately nitrified in the soil and so made use of by the plant. The Indore process can easily be carried out, not only in the tropics but also on the small holdings of the temperate regions and on the allotments (provided space is made available) in the neighbourhood of urban areas, where it is now the practice to burn most of the vegetable waste. How rapidly the system can be introduced into the farming systems of the Occident is a question to which no answer can be given until the ideas in this book have been fully tried out in western agriculture. It is not impossible that they may founder for a time on the present high cost of labour. The method however is in full accord with the well-marked tendency in western agriculture towards a more intensive production. The inevitable change over from extensive to intensive methods has already begun. For production to be more economical, the acre yield must be increased. Already in the United States the suggestion has been made that the line of advance in crop production lies in restricting the area cultivated. A portion of the impoverished prairie lands should go back to grass. The crops needed should be raised from a smaller area. These ideas will become practicable the moment the farmer learns how to utilize the waste products of his fields in increasing the fertility of the soil. This is the greatest need of agriculture at the present day.


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.

Ducker, H. C. -- 'Soil Erosion Problems of the Makwapala and Port Herold Experiment Stations, Nyasaland,' Empire Cotton Growing Review, 8, 1931, p. 10.

Felsinger, E. O. -- 'Memorandum on a System of Drainage Calculated to Control the Flow of Water on Up-country Estates, with a view to reducing Soil Erosion to a Minimum,' Tropical Agriculturist, 71, 1928, p. 221; 74, 1930, p. 68.

Howard, A. -- Crop Production in India, a Critical Survey of its Problems, Oxford University Press, 1924.

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, 1926.

Lipman, J. G. -- 'Soils and Men,' Proc. of the Inter. Congress on Soil Science, Washington, D.C., 1928, p. 18.

Matthaei, L. E. -- More Mechanization in Farming, International Labour Review, Geneva, 23, 1931, p.324.

Percy, Lord Eustace -- Education at the Cross Roads, London, 1930.

Report of the Royal Commission on Agriculture in India, Calcutta, 1928.

Riddell, W. A. -- 'The Influence of Machinery on Agricultural Conditions in North America,' International Labour Review, Geneva, 13, 1926, p. 309.

Wagner, W. -- Die Chinesische Landwirtschaft, Berlin, 1926, p 222.

Next: 2. Organic Matter and Soil Fertility

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