1.1 Vermicomposting is basically a managed process of worms digesting organic matter to transform the material into a beneficial soil amendment. As per the USDA guidelines for compost practices (with effect from Oct 21, 2002), vermicomposts are defined as organic matter of plant and/or animal origin consisting mainly of finely-divided earthworm castings, produced nonthermophilically with biooxidation and stabilization of the organic material, due to interactions between aerobic microorganism and earthworms, as the materials pass through the earthworm gut.
1.2 Good quality compost production in ambient temperature can be accomplished in shorter time by the process of vermicomposting that involves use of proper species of earthworms. The native cellulase activity of earthworms and microorganisms in earthworm gut promote faster decomposition of ingested organic material. The combined effect of enzymatic activity and grinding of organic materials to fineness by earthworms produces the vermicomposting and this is not observed in compost pits without earthworm.
1.3 The earthworms being voracious eaters consume the biodegradable matter and give out a part of the matter as excreta or vermi-castings. The vermi-casting containing nutrients is a rich manure for the plants. Vermicompost, apart from supplying nutrients and growth enhancing hormones to plants, improves the soil structure leading to increase in water and nutrient holding capacities of soil. Fruits, flowers and vegetables and other plant products grown using vermicompost are reported to have better keeping quality. A growing number of individuals and institutions are taking interest in the production of vermicompost utilising earthworm activity. As the operational cost of production of this compost works out to less than ` 2.0/Kg., it is quite profitable to sell the compost even at ` 4.00 to ` 4.50/Kg.
2.1 The process of composting crop residues / agri wastes using earthworms comprise spreading the agricultural wastes and cow dung in gradually built up shallow layers. The pits are kept shallow to avoid heat built-up that could kill earthworms. To enable earthworms to transform the material relatively faster a temperature of around 300 C is maintained. The final product generated by this process is called vermicompost which essentially consist of the casts made by earthworms eating the raw organic materials. The process consists of constructing brick lined beds generally of 0.9 to 1.5 m width and 0.25 to 0.3 m height are constructed inside a shed open from all sides. For commercial production, the beds can be prepared with 15 m length, 1.5 m width and 0.6 m height spread equally below and above the ground. While the length of the beds can be made as per convenience, the width and height cannot be increased as an increased width affects the ease
2.2 Cow dung and farm waste can be placed in layers to make a heap of about 0.6
to 0.9 m height. Earthworms are introduced in between the layers @ 350 worms
per m3
of bed volume that weighs nearly 1 Kg. The beds are maintained at about
2
40-50% moisture content and a temperature of 20–30o
C by sprinkling water over
the beds.
2.3 When the commercial scale production is aimed at, in addition to the cost of
production, considerable amount has to be invested initially on capital items. The
capital cost may work out to about `5000 to `6000 for every tonne of
vermicompost production capacity. The high unit capital cost is due to the fact
that large units require considerable expenditure on preparation of vermi beds,
shed to provide shelter to these beds and machinery. However these expenditures
are incurred only once.
2.4 Under the operational cost, transportation of raw materials as also the
finished product are the key activities. When the source organic wastes and dung
are away from the production facility and the finished product requires
transportation to far off places before being marketed, the operational cost would
increase.
2.5 However, in most of the cases, the activity is viable and bankable. Following
are the items required to be considered while setting up a unit for production of
vermi-compost.
3.1 Of about 350 species of earth worms in India with various food and burrowing
habits Eisenia fetida, Eudrilus eugeniae and Perionyx excavatus are some of the
species that are reared to convert organic wastes into manure. A combination of
epigeic species that form no permanent burrows and live on the surface, anecic
that form semi-permanent and vertical burrows extending from the surface and
endogeic that typically live throughout the deeper layers may be considered.
3.2 The worms feed on any biodegradable matter and vermicomposting units are
ideally suited for locations / units with generation of considerable quantities of
organic wastes. One earthworm reaching reproductive age of about six weeks lays
one egg capsule (containing 7 embryos) every 7-10 days. Three to seven worms
emerge out of each capsule. Thus, the multiplication of worms under optimum
growth conditions is very fast. The worms live for about 2 years. Fully grown
worms could be separated and dried in an oven to make 'worm meal' which is a
rich source of protein (70%) for use in animal feed.
Rural areas with predominance of agriculture, suburbs of cities and peri urban villages are considered ideal locations for setting up of vermicomposting units on a larger scale from the view point of availability of raw material and marketing of the produce. As use of the compost is said to have ameliorative effect more particularly on fruit, vegetable, plantation and ornamental crops, vermicomposting units may be located in areas with concentration of fruit and vegetable growers and floriculture units. Further, the nearness to a commercial dairy unit or large concentration of cattle population will have an added advantage of cheap raw material i.e. cow dung.