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 seaside 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.
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.
Next: 4. The Indore Process
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