Due to gradually increasing population and industrialization, the amount of waste is increasing day-by-day. Therefore, utilization of waste has become a problem for many heavily populated countries like China and India. Therefore, besides biogas and electric production, some of the methods of waste utilization are given below:
Vermicomposting :
Vermicomposting is the phenomenon of compost formation by applying the earthworms. Earthworms play an important role in the cycling of plant nutrients, turnover of organic matter and maintenance of soil structure. They can consume 10-20% of their own biomass per day.
The most important effect of earthworms in agro-ecosystems is the increase in nutrient cycling, particularly nitrogen. They ingest organic matter with a relatively wide C:N ratio and convert it to earthworm tissue with a lower C:N ratio. Thus, they affect the physicochemical properties of soil.
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Vermicompost is an excellent source of nutrients for vegetables ornamentals, fruit and plantation crops. Using vermicomopost, one can get 10-15% more crop yield, besides improvements in quality of the product. For the first time, in 1970, vermicomposting was started in Ontario (Canada).
In recent years, the U.S.A., Japan and Philipines are the leaders of vermicompost producers. So far least attention has been paid in India. But is recent years, Government and non-Government Organisations (NGOs) are trying to popularise the vermicomposting process.
Vermicomposting is also being done at Shanti Kunj (Haridwar). One kg earthworm can consume 1 kg organic materials in a day. They secrete as casting which are rich in Ca, Mg, K, N and available P. Depending on substrate quality, vermicompost cosists of 2.5-3.0% N, 1-1.5% P and 1.5-2% K, useful microorganisms (bacteria, fungi actinomycetes, protozoa), hormones, enzymes and vitamins.
About 500 species of earthworms are known in India and over 3,000 in the world. The most common members of the earthworm to be used in vermicomposting include: Eisenia andrie, E. coetida, Dravida willsii, Endrilus euginee, Lamito mauritii, Lubrieus rubellus and Perionyx excavatus.
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Process of Vermicomposting :
Process of vermicomposting can be done in pits or concrete tanks, wells or wooden crates. A pit of 2 x 1 x 1 m3 dimension (1 m maximum depth) is dug under a shade to prevent the entry of water during rain.
Wooden brinks or pebbles are spread on the bottom of pit followed by coarse sand to facilitate the drainage. It is covered by layer loamy soil which is moistened and inoculated by earthworms.
It is covered by small lumps of fresh or dry cattle dung followed by a layer of hay or dry leaves or agro-wastes. Every day for about 20-25 days water is sprinkled over it to keep the entire set up moist.
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Until the pit is full dry and green leaves are put into the pit in each week. Vermicompost is ready after 40-45 days. Vermicompost appears soft, spongy, dark brown with sweet smelling. Then it is harvested and kept in dark. It is sieved and packed in polythene to retain 20% moisture content.