Organic fertilizers have a number of beneficial impacts on land.  They not only supply major nutrients to crops, but also improve the physical conditions of soil.  Additionally, they supply a fair quantity of micro-nutrients, which are particularly deficient in intensively cultivated plots.  Organic fertilizers so promote beneficial microbial processes in the soil, improve soil structure, aeration and water holding capacity.  Finally, they prevent soil erosion and improve the drainage. 

These are two common types of organic fertilizers: bulky and concentrated.  The former variety, which are derived from plant and animal sources such as farm yard manure, compost, green manure and crop residues, are voluminous and supply low quantities of major plant nutrients.  The latter contain higher percentages of major plant nutrients and are typically derived from oil cakes, poultry manure, fish meal, blood and meat meals, and guano. 

A third type of organic fertilizer, vermicompost, is less commonly used.  It consists of the cast, or excreta, or epigamic earthworms which have been cultured on animal dung or other organic wastes.  Vermicompost is typically added to the soil in a manner similar to that used in other kinds of organic manure. 

In recent years, vermicomposting has begun to attract attention, as certain sections of the agricultural and scientific communities have advocated its use as an alternative, and potentially more effective, form of fertilizer.  This is a controversial claim.  Not only is vermicompost more difficult to prepare, its nutritive content has not been conclusively shown to be better than that possessed by conventional organic fertilizers. 

Traditional organic fertilizers are relatively easy to prepare.  The two most widely-used methods of preparation are the Indore and Bangalore methods. 

The Indore method is an aerobic process of composting, in which organic waste material is kept in a heap or pit between alternate layers of dung and soil.  Typically, about fifteen centimetres of organic waste matreial are covered with a five centimetre layer of dung, and sprinkled with soil.  Theis process is repeated until the heap reaches a height of about one and a half meters.  Optimal levels of moisture are ensured by sprinkling water on each layer.  The heap is then turned two to three times, and will be ready for use in abour three months time. 

The Bangalore method is an anaerobic process in which the composting is done in trenches measuring approximately two and a half meters in width, and one meter in depth.  About fifteen centimetres of the material to be composted is placed in the trench, properly compressed, and sprinkled with a five centimetre layer of dung.  The pile is watered periodically to maintain optimum moisture conditions.  Alternately, a mixture of dung and water (about one kilogram of dung in about ten litres of water) may be used for the purpose. 

The process is repeated until the trench is filled up to a height of about one metre above the ground level.  This is shaped into a dome and plastered with a mixture of mud and dung.  After five and a half months, the compost should be ready for use. 

Conventional organic fertilizers, then, are demonstrated to rely chiefly on the activity of micro-organisms to break down organic residues of plant and animal origin.  Their preparation places relatively little demands on the farmer’s time, attention or finances. 

Vermicomposting, on the other hand, is a more laborious and expensive process.  First, all non-organic matter (such as metal, rubber, plastic, and glass) must be separated from the material to be composted.  Then, the latter must be broken up into small units of about one cubic centimetre.  This material must then be partially composted for at  least two weeks before earthworms can be introduced, since the heat generated during the mesophilic and thermophilic stages of decomposition can destroy the worms.  Only when the waste material has been composted beyond this point can worms be introduced. 

The vermicomposting process per se beings when the partially composted organic waste is transferred to containers standing about three-fourths of a meter above the ground.  These containers, which must be made of brick, cement, wood or plastic, will involve varying degrees of financial expenditure by the farmer.  Additionally, the receptacles should be protected from direct sunlight and precipitation, and placed in a room or under a thatched roof.  This requirement, too, can place a financial burden on the farmer. 

The height of the waste pile placed in these receptacles should not exceed sixtenths of a meter.  Earthworms are then introduced into these containers to ingest and transform the organic waste into vermicompost.  To aid them in this process, the pile must be watered at least once a day, to maintain the necessary moisture levels and softness of the waste.  Hence, the vermicomposting process requires access to a water-source on a daily basis throughout the year.  Then, after about two to three weeks of composting, the worms can be removed from the pile, and the vermicompost will be ready for use. 

In spite of these efforts, however, the farmer will still be unable to guaranteee that the worms will successfully complete the composting process in every instance.  Earthworms are delicate creatures, and can only survive in a narrow temperature range below thirty degrees centigrade. 

Thus, in spite of frequent watering and shelter, they will probably perish in most parts of the country during the summer months, when temperatures can rise to about forty-five degrees.  Hence, the utility of vermicomposting as a perennial source of fertilizer is questionable. 

Additionally, earthworms are exceedingly vulnerable to injury, and attract a wide number of predators, such as ants, rats,  dogs and moles.  In the eventuality of injury, hurt worms are liable to contract and spread infections to their healthy neighbours.  Thus, a single accident could place a whole composting pile in jeopardy, and potentially inflict significant losses (in terms of time and financial expenditures) on the farmer. 

Finally, and perhaps most importantly, the supposed superiority of the nutrient content of vermicompost is rather debatable.  A.C. Gaur’s `Review of Soil Research in India, reports that the organic fertilizer prepared from farm litter had 0.5%, 0.2% P<sub>2</sub>O<sub>5</sub> and 0.5%K2O, whereas the corresponding figure for compost required from town waste (e.g. garbage, night soil) are 1.5, 1.0 and 1.5 per cent.  Compost prepared from water hyacinth has 2.0% N and 2.3% K2O.  Sheep and goat manure contain 3% N, 2.63% P and 1.4% K. Vermicomposts, on the other hand, contained only 0.66% N, 0.99% P and 0.4% K as quoted by R. Kale and K. Bano in the `State of the Art Report on Vermiculture in India’. 

Similarly, while J. Haimi and V. Huhta observe in `Pedo Bioglogiea’ that, worm worked compost differs from worm-less compost in physical structure and the time required for preparation, Shinde, Naik, Nazirkar, Kalam and Khair note in the `Proceedings of the National Seminar on Vermicomposting’ that, there is no significant difference between the nutrient content of farm-cultured vermicompost and other, conventional organic fertilizers.  Commercial vermicomposts were demonstrated to be significantly poorer than either of these varieties. 

Therefore, it becomes clear that while vermicomposting requires greater investments of time, labour and money, it does not yield a correspondingly better quality of organic fertilizer.  Moreover, it depends on a rather intricate preparation process that is vulnerable to failure on account of a large number of extraneous factors.  In the event of such failure, the investments made by the farmer in the vermicomposting process could potentially be adverse, if not actually ruinous.  The merits of vermicomposting, then, deservedly remain a topic of much controversy.  q