**2.2 Classification of earthworm**

There are about 3320 species of earthworms all over the world [37], but hardly 8–10 species are suitable for vermicompost preparation. Earthworms have been extensively utilized for the recycling of a variety of organic wastes like municipal solid wastes [38] wheat straw [39], sewage sludge [40], forestry waste [41], vegetable waste [42], farmyard manure [43], sorghum stalk, wheat straw, paddy straw [44], coir pith [45]. Renowned scientists, Charles Darwin called earthworms as the 'unheralded soldiers of mankind', and Aristotle described them as the 'intestine of earth', as they could digest a wide range of organic materials [46, 47]. On the basis of morphoecological characteristics, earthworms have been classified into three categories [48]; Anecic (Greek word "out of the earth") – these are burrowing worms that only come to the surface at night to drag food down into their permanent burrows deep within the mineral layers of the soil. Endogeic (Greek word "within the earth") – these are also burrowing worms but their burrows are typically more shallow and they feed on the organic matter inside the soil, so they come to the surface only rarely. Epigeic (Greek word "upon the earth") – these worms live on the surface litter and feed on decaying organic matter. They do not have any permanent burrows. These "decomposers" are the type of worm used in vermicomposting. Two tropical species, African night crawler, *Eudrilus eugeniae* (Kinberg) and Oriental earthworm, *Perionyx excavates* (Perrier) and two temperate ones, red earthworm, *Eisenia andrei* (Bouche) and tiger earthworm, *Eisenia fetida* (Savigny) are extensively used in vermicomposting [49–51]. Most vermicomposting facilities and studies are using the worms *E. andrei* and *E. fetida* due to their high rate of consumption, digestion, and assimilation of organic matter, tolerance to a wide range of environmental factors, short life cycles, high reproductive rates and endurance and resistance during handling [52]. A few other species *Drawida nepalensis*, *Lampito mauritrr. Dichogaster* spp., *Polypheretima elongate, Amynthas* spp. *Dendrobaena octaedra, Eisenia hortensis* [53] have also been used for composting under specific conditions.

### **2.3 How does earthworm facilitate vermicomposting?**

Earthworms promote the growth of "beneficial decomposer aerobic bacteria" in organic waste material and also act as a grinder, crusher, chemical degrader and a biological stimulator of waste material [54, 55]. Earthworm hosts millions of decomposer (biodegrader) microbes [56], hydrolytic enzymes and hormones that helps in rapid decomposition of complex organic matter into vermicompost in a relatively smaller duration of 1–2 months [57] as compared to traditional composting method which takes nearly 5 months [58]. The mechanism of formation of vermicompost by earthworms occurs in following steps; organic material consumed by earthworm is softened by the saliva in the mouth of the earthworms. Food in esophagus is further softening and neutralization by calcium and physical breakdown in muscular gizzard results in particles of size <2 μ, thereby giving an enhanced surface area for microbial processing. This finally ground material is exposed to various enzymes such as protease, amylase, lipase, cellulase and chitinase secreted in lumen by stomach and small intestine [12]. Moreover, microbes associated with intestine facilitate breaking down of complex biomolecules into simple compounds. Only 5–10% of the ingested material is absorbed into the tissues of worms for its growth and the rest is excreted as vermicast. The vermicast is a good organic fertilizer and soil conditioner. High-quality vermicast can be produced by worms such as the red wrigglers (*E. fetida*) as it contains humus with high levels of nutrients that has good potential for the production of organic fertilizer. Vermiwash is a liquid fertilizer and used as a foliar spray produced by passing water through columns of vermiculture beds [59].

#### **2.4 Suitable environmental conditions for earthworms**

Optimum conditions of temperature 15–20°C (limits 4–30°C), Moisture content 80–90% (limits 60–90%), Oxygen – Aerobicity, Ammonia content of the waste Low: <1 mg·g–1 (0.016 oz.1b–1), Salt content Low < 0.5% and pH of 5–9 are preferred for stable life cycle of earthworm.

#### **2.5 Starter food for multiplication of earthworms**

To attain the desired earthworm population their starter food includes 1:1 mixture of cow dung and decaying leaves in a cement tank/wooden box/plastic bucket with proper drainage facilities and on attaining sufficient number of earthworms, subsequently other sources of organic wastes can be provided. Compost worms being voracious feeders, consume in excess of their body weight each day but they prefer some foods to others. Manures are the most commonly used worm feedstock, with dairy and beef manures generally considered the best natural food for *E. fetida* [60]. The unit should be kept in shade. Sufficient moisture level should be maintained by occasional sprinkling of water. Within 1–2 months, the worms multiply 300 times, which can be used for large scale vermicomposting.

#### **3. Methods of vermicomposting**

Earthworms are used to convert organic waste material into dark brown nutrient rich humus that is a good source of manure for plants. Worms can also degrade specific pollutants and might allow community formation of useful microorganisms. Three commonly used methods for vermicomposting are discussed below:

1.Bin composting: The most common method for small scale composting is bin composting method. The bin can be constructed of several materials such as wooden/plastic/recycled containers like bathtubs and barrels. A vermicompost bin may be in different sizes and shapes, but its average dimensions are 45 × 30 × 45 cm. Around 10 holes with 1–1.5 cm in diameter holes in bottom, sides and cap of bin is useful for aeration and drainage.

**49**

*Vermicomposting: An Effective Option for Recycling Organic Wastes*

of the pit should be made hard with a wooden mallet.

**4. Conventional steps involved in vermicomposting**

2.Pit composting: For large scale composting, pits of sizes 2.5 m × 1 m × 0.3 m under thatched sheds with sides left open are advisable. The bottom and sides

3.Pile composting: Pile method is mostly used for vermicomposting in larger scale. The piles can be made in porch place like greenhouse or in a floor with some facilities for drainage in warm climate. The pile size may vary in length and width, however, its height is average height of bin used for bin

Prior to the vermicomposting process, it is preferred to assign pre-composting of organic waste (thermophilic composting), which comprises a short period of high temperature for facilitating mass reduction, waste stabilization, and pathogen reduction [61, 62]. Thermophilic composting results in sanitization of organic wastes and elimination of toxic compounds [63]. Although pathogen removal occurs during transit in the worm gut [64] but thermophilic composting prior to vermicomposting is advisable to avoid the earthworm mortality. Then, after some days of high temperature, pre-mature compost is cooled by spreading it as thin layers on vermicomposting beds. Vermicomposting can be done either in containers,

1.**Materials required for vermicomposting:** Carbon and nitrogen-rich organic materials, spade, ground space, stakes, hollow blocks, plastic sheets or used sacks, water (according to the season) and water sprinklers, shading materials, nylon net or any substitute to cover the beds, and composting earthworms.

2.**Site Selection:** Vermicompost production can be done at any place which is having shades, cool and has high humidity. For instance, abandoned cattle shed, or poultry shed or unused buildings or artificial shading could also be

3.**Shredding of organic waste material:** The collected organic waste material should be processed for shredding along with mechanical separation of the

4.**Pre-digestion of organic waste material:** Pre-digestion of organic waste should be done for at least 20–25 days prior by mixing the waste material along with raw material (e.g., cattle dung slurry). Regular watering is required for partially digesting it and making it fit for earthworm consumption. Raw material to be used includes for composting – cow dung, crop residues, farm wastes, vegetable market wastes and fruit wastes. Cow dung should be at least 20–25 days old to avoid excess heat generation during the composting process. Moreover addition of higher quantities of acid-rich substances such as citrus wastes should be avoided. It is important to mix carbonaceous with nitrogenous organic materials at the right proportions to obtain a C: N ratio of about 30:1, as it results in product of highest stability, the best fertilizer-value and with lowest potential for environmental pollution. For example, rice straw and fresh manure are mixed at about 25:75 ratio by weight. When the material with higher carbon content is used with C:N ratio exceeding 40:1, it is advisable to

add nitrogen supplements to ensure its effective decomposition.

metal, glass and ceramics that should be kept aside.

*DOI: http://dx.doi.org/10.5772/intechopen.91892*

composting.

pits or piles.

provided.

*Organic Agriculture*

(biodegrader) microbes [56], hydrolytic enzymes and hormones that helps in rapid decomposition of complex organic matter into vermicompost in a relatively smaller duration of 1–2 months [57] as compared to traditional composting method which takes nearly 5 months [58]. The mechanism of formation of vermicompost by earthworms occurs in following steps; organic material consumed by earthworm is softened by the saliva in the mouth of the earthworms. Food in esophagus is further softening and neutralization by calcium and physical breakdown in muscular gizzard results in particles of size <2 μ, thereby giving an enhanced surface area for microbial processing. This finally ground material is exposed to various enzymes such as protease, amylase, lipase, cellulase and chitinase secreted in lumen by stomach and small intestine [12]. Moreover, microbes associated with intestine facilitate breaking down of complex biomolecules into simple compounds. Only 5–10% of the ingested material is absorbed into the tissues of worms for its growth and the rest is excreted as vermicast. The vermicast is a good organic fertilizer and soil conditioner. High-quality vermicast can be produced by worms such as the red wrigglers (*E. fetida*) as it contains humus with high levels of nutrients that has good potential for the production of organic fertilizer. Vermiwash is a liquid fertilizer and used as a foliar spray produced

Optimum conditions of temperature 15–20°C (limits 4–30°C), Moisture content 80–90% (limits 60–90%), Oxygen – Aerobicity, Ammonia content of the waste Low: <1 mg·g–1 (0.016 oz.1b–1), Salt content Low < 0.5% and pH of 5–9 are pre-

To attain the desired earthworm population their starter food includes 1:1 mixture of cow dung and decaying leaves in a cement tank/wooden box/plastic bucket with proper drainage facilities and on attaining sufficient number of earthworms, subsequently other sources of organic wastes can be provided. Compost worms being voracious feeders, consume in excess of their body weight each day but they prefer some foods to others. Manures are the most commonly used worm feedstock, with dairy and beef manures generally considered the best natural food for *E. fetida* [60]. The unit should be kept in shade. Sufficient moisture level should be maintained by occasional sprinkling of water. Within 1–2 months, the worms multiply

Earthworms are used to convert organic waste material into dark brown nutrient rich humus that is a good source of manure for plants. Worms can also degrade specific pollutants and might allow community formation of useful microorganisms.

1.Bin composting: The most common method for small scale composting is bin composting method. The bin can be constructed of several materials such as wooden/plastic/recycled containers like bathtubs and barrels. A vermicompost bin may be in different sizes and shapes, but its average dimensions are 45 × 30 × 45 cm. Around 10 holes with 1–1.5 cm in diameter holes in bottom,

Three commonly used methods for vermicomposting are discussed below:

sides and cap of bin is useful for aeration and drainage.

by passing water through columns of vermiculture beds [59].

**2.4 Suitable environmental conditions for earthworms**

ferred for stable life cycle of earthworm.

**3. Methods of vermicomposting**

**2.5 Starter food for multiplication of earthworms**

300 times, which can be used for large scale vermicomposting.

**48**

