The Waste Products of Agriculture -- Their Utilization as Humus

by Albert Howard and Yeshwant D. Wad

Chapter 6
Application to Other Areas

In the present chapter, the various adaptations that will be needed, and the further investigations that must be undertaken before the Indore process can be widely adopted, will briefly be considered.


As far as the tropics and sub-tropics are concerned, the process can be adopted as it stands. No particular difficulties are likely to be encountered at any stage. After the collection, storage and admixture of the raw materials, including dung and urine earth, the two chief factors on which success depends are: (1) the maintenance of a high temperature in the pits or heaps; and (2) adequate aeration throughout the manufacture. With ordinary care, temperature difficulties are unlikely to occur, as the daily mean in these regions is always high, and the occasional cold spells are of short duration. All that is needed is the proper orientation of the pits or heaps to prevent overdue cooling by high winds, particularly during the interval between charging and the first turn. The maintenance of the correct degree of aeration requires more care. The chief difficulty likely to arise is the flooding of the pits after heavy rain or by the rise of the ground water. The material then becomes thoroughly soaked, and adequate aeration is impossible. If this overwatering cannot be prevented by catch drains, pits will have to be given up and the manufacture conducted in heaps on the surface. Direct wetting through heavy falls does little or no permanent harm (but see Chapter 5, Table XI for the temporary effects). This was clearly established at Indore during the monsoon of 1930, when the total rainfall was forty-five inches, most of which was received between I5 June and 15 September. This included five falls of over two inches and two of over five inches in twenty-four hours. In spite of these heavy downpours, the conversion proceeded evenly and without difficulty; there was little or no loss of soluble nitrogen by leaching; the amount of moisture absorbed from the rainfall did not interfere with the oxygen supply. For these reasons it is not necessary in warm countries to carry on the manufacture under cover. The erection and maintenance of sheds therefore need not be considered.

In the damper areas of the tropics like parts of Africa and the West Indies, which do not possess a cattle force at all comparable with that of India, a difficulty in maintaining the correct carbon-nitrogen ratio of the mixture may occur. There may be insufficient dung and urine earth for converting the large quantities of vegetable wastes which are available. The shortage can be made up by the use of nitrate of soda or by the Adco powders. If such artificials are employed, it will be a great advantage to make use of soil as the principal base for keeping the general reaction uniform and within the optimum range. Soil is the best base for neutralizing acidity and for absorbing ammonia and is far more effective than lime or wood ashes. This material possesses two other important advantages in the making of compost. In the first place, the soil colloids are very retentive of moisture and so help to keep the water content of the mass steady. In the second place, the colloids cover the vegetable matter with a thin adherent film which can retain in situ all the materials -- combined nitrogen and minerals, soluble carbohydrates, water and oxygen essential for the rapid development of the micro-organisms. The result is that there is no delay in the breaking down of the vegetable wastes and in the synthesis of microbial tissue. When earth is omitted from the mixture, two difficulties at once arise. The supply of moisture for the microorganisms is intermittent; the general reaction becomes inconsistant. Delays ensue. For these reasons, the Adco process could easily be improved by the judicious use of earth. If lime were omitted from the Adco mixture, the freight on this item could be saved and the usefulness of the rest of the powder increased.

In those areas of the temperate regions where winter occurs, one important modification of the process may be needed. As will be evident from a study of the results set out in Chapter V, one of the difficulties against which provision has to be made is the lowering of the temperature of the fermenting mass by cold and wind. For the micro-organisms to complete the conversion in ninety days, the heaps must be kept at a high temperature throughout. No difficulties are likely to arise during the summer. Trouble however is likely during the colder months -- November to April. During this period the fermentation may have to be carried out in sheds or in compost houses on the Japanese principle. Many existing farm buildings could be adapted for the purpose; the ideal structure however would have to be designed -- a task which will be lightened after a careful study of the methods in use in those areas of Japan where compost houses are the rule.

The difficulty of adopting the system in countries like Canada, the United States and Great Britain, where labour is dear and scarce, will be solved by the mechanization of the process. The first step would be for one or two of the experiment stations to transform all their vegetable wastes into compost by hand labour regardless of expense, and then to determine the value of the product in maintaining crop production at a high level. The full possibilities of humus will only appear when the dressings of compost are supplemented by the addition of suitable artificials. The combination of the two, applied at the right moment and in proper proportions, will open the door to the intensive crop production of the future. Humus and artificials will supplement one another. Further, the artificials must not be confined to those which merely supply nitrogen, phosphates and potash. Substances like lime and sulphur, which flocculate the soil colloids and so improve the filth, must be included.

In other words, the manuring of the future wild have to be both direct and indirect.

Further Investigations

In the tropics and sub-tropics, an important aspect of the process is its application to the future sanitation of the village. The fact that forty oxen are kept at the Institute of Plant Industry, Indore, and that compost is manufactured throughout the year, without the slightest smell and without the breeding of flies, indicates clearly the line of advance in dealing with village sanitation. All that appears to be needed is to adapt the Indore process (which employs cow-dung and urine earth) to the use of night soil, and to utilize the present sanitary services in showing the people how to transform the village wastes (including all forms of litter of vegetable origin) into compost. No difficulties are likely to be experienced in the actual conversion of the waste products of the rural population into humus. The process will be more rapid than when cow-dung is used: a factor which is all to the good. Besides the valuable compost that will be obtained, a number of other advantages will follow. Rural hygiene will enter on a new phase. The fly nuisance will disappear. Practically all the infection, which is now carried by these insects from filth to the food and water supply of the population, will be automatically destroyed by the combination of high temperature, high humidity and copious aeration of the compost heaps. In the tropics parasites like hookworm will tend to decrease in numbers. A rapid improvement in the general health and the amenities of the village will ensue. What is needed to bring about these results is the working out of a simple process on the lines of the one described in this book. It will not prove a difficult. It will be easy to-design a series of screened pits and screened areas in the neighbourhood of an Indian village, and to teach the sweepers how to carry on the manufacture of compost without smell and without the breeding of flies. The conditions which render these two nuisances impossible will at the same time destroy practically all the harmful parasites and germs which now infect the population. Provided the work is carried out by the village scavengers, no caste difficulties are likely to arise. The process can easily be welded into the existing village system. A beginning has been made in the direction indicated by Mr. F. L. Brayne, I.C.S., Deputy Commissioner of Jhelum (formerly Deputy Commissioner of Gurgaon). Mr. Brayne has designed a latrine pit, which without much difficulty could be perfected for use throughout the tropics and sub-tropics. The method will have to be adapted both to dry weather and to monsoon conditions, and will have to be worked for a year or two under strict microbiological and chemical control before being brought to the notice of the people. Work on these lines has already been started in the model village belonging to the Institute of Plant Industry at Indore. If, as seems certain, a practicable method can be devised, steps will at once be taken to get it taken up in the villages of the Central India and Rajputana States. Its spread to the rest of India, and all over the tropics and subtropics, will be a matter of a very few years.

The moment a suitable method of dealing with the sanitation of the village has been designed and the influence of the process on the general health of the people and on the fertility of the fields becomes manifest, the results can be carried further. The public health of the military cantonments and of the smaller towns can then be considered as one subject. In place of the present expensive division of those aspects of the general problem of sanitation, which deal with solid wastes, into a number of imperfectly related items, such as -- the disposal of night soil, the use of disinfectants, the collection and destruction by burning of vegetable wastes including fallen leaves, the prevention of the fly nuisance, the purlfication and safeguarding of the water supply and the inoculation of the population against such diseases as enteric fever and cholera -- it will be possible to transform these waste products of the population into valuable humus in a scientific way, and so avoid most if not all the existing difficulties. Such results, as far as urban areas are concerned, will naturally be the work of years. In the villages, however, progress should be rapid. The first important step on the road has already been taken in the form of the Indore process. It will not be a difficult matter to expand the opening which has been made. Little increase in public expenditure will be called for. The funds and staff, now devoted to rural hygiene, can at once be deflected to the manufacture of compost and to increasing the produce of the soil.


Brayne, F. L. -- The Remaking of Village India, Oxford University Press, 1929.

Hall, A. D. -- ' Some Secondary Actions of Manures upon the Soil,' Journ. of the Royal Agric. Soc. of England, 70, 1909, p. 12.

Howard, A. and Howard, G. L. C. -- The Application of Science to Crop Production, an Experiment carried out at the Institute of Plant Industry, Indore, Oxford University Press, Bombay, 19Z9.

King, F. H. -- Farmers of Forty Centuries or Permanent Agriculture in China, Korea and Japan, London, 1926.

Next: Appendix A. The Manurial Problem in India

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