Vermicomposting is one of the types of composting technique, which turns the organic debris into a humus-like product, by the use of earthworms. The compost produced by this method refers as “Vermicompost”. The vermicompost can merely define as earthworm’s excrement, which provides essential nutrients, aeration, porosity, structure, fertility and water-holding capacity to the soil and plant body.
The method of vermicomposting requires an average temperature range between 15-25 degrees Celsius, tropical climate and the use of green waste. It most commonly uses Eisenia fetida for the decomposition of organic green waste, due to their best appetites and breeding ability.
- Mechanism of digestion
- Worm Tea
Vermicomposting can define as an aerobic process of preparing organic compost by decomposing the animal and plant waste by the association of earthworms. The compost obtained by this method commonly refers to as “Vermicompost”. Worms digest the agro, plant and farm waste by the grinding action of their gizzard and excrete granular casts that also refers as “Vermicast or Vermicompost”. The earthworm casting contains simpler nutrients like nitrogen, phosphorus, potassium, calcium, magnesium, etc., which can be directly used up by the plant.
Vermicomposting method targets on the following objectives:
- Production of quality compost.
- Participates in waste recycling and solid-waste management by recycling the agro and farm waste into useful bioorganic manure.
- To increase the crop yield, by providing fertile soil.
- Promotes the organic farming system.
- Augmentation of food production.
- Allocates employment opportunities to the members of a rural family.
It can define as the useful, granular castings excreted by the earthworm as a result of the complete digestion of agro-waste, farm-waste etc. Therefore, it also refers to as “Vermicasting”. Around 1000-1200 of worms are required to decompose 1kg/q of organic matter.
The process of vermiculture requires feedstock or raw materials like plant and animal excreta and makes the use of earthworms to breakdown the organic matter into simpler minerals and nutrients. In addition to this, it requires water to maintain 40% of minimum moisture content.
It includes organic green wastes like a waste coming from farms, kitchen, forest etc. The ratio of waste and dung should be 1:1. Raw materials act as feedstock for the earthworms, which should have the following ideal properties:
- It should contain 75% of water content.
- The density should be below 640lb/ft3.
- It should be devoid of any chemical, pesticide and tannins residues.
These can be epigeic, endogeic and anecic in habitat. Eisenia fetida is a red wiggler which is mostly preferred over the other types. It can decompose and convert the organic matter into vermicompost within 45-50 days or has a high metabolic rate. Eisenia fetida is the most common species of earthworm that is used throughout the world for the vermiculture technique.
Mechanism of digestion
The earthworm first, take up the organic debris like plant and animal waste into their gut. Then the organic matter passes from the earthworm’s gut, where first mineralizes into ammonium, and later nitrifies into the plant’s mineral and nutrients. The grinding action of gizzard and the chemicals of the digestive tract helps in the conversion of organic debris into the simpler plant’s nutrients. A movement of gut muscle helps in the release of granular, rich in nutrient source Vermicast.
Process of Vermicomposting
The method of vermiculture involves the collection of earthworms, construction of compost pit or bed, harvesting of compost, packaging, and marketing.
How to collect Earthworms
It includes the following steps:
- First, observe the earthworm castings over the soil surface.
- Then make a solution containing 500g of jaggery, 500g of cow dung and 2l of water.
- After that, sprinkle the above solution over the soil surface about an area of 1m X 1m.
- Cover with straw lumps, and then with the old jute bag, and keep sprinkling the solution for about 20-30 days.
- Finally, we can collect the earthworms after their aggregation towards the spot.
Methods of Vermicomposting
The vermiculture is a method of producing vermicompost, which can be achieved by the construction of either compost pit or compost bed.
It can be constructed in a backyard or field that is usually carried out in a cemented pit. The recommended size of the pit is 5X5X3 feet but can vary with the volume of biomass and agricultural waste. The ditch is generally covered with the thatched grasses, dry leaves, twigs etc.
Compost pit is usually a non-preferred method because of aeration and drainage problems. To prevent the entry of ants from attacking the earthworms, the water column should be in the centre of parapet wall of compost pit.
It also refers to as “Compost-bed” that prefers over the method of vermiculture through compost pit. To construct Vermibed, we need to do the following steps:
Step-1: Prepare the first layer, by adding loamy soil at the bottom of thickness about 15-20 cm.
Step-2: Prepare a second layer, by adding broken sticks, pebbles, coarse sand of thickness about 5cm.
Step-3: It is the most crucial step that involves the addition of earthworms. Around 150 worms are added to the compost bed of area 2m X 1M X 0.75M with a thickness of 15-20cm.
Step-4: Prepare the fourth layer by addressing some animal waste like cow dung, goat dung etc. Over this, add a layer of agro-waste like dry-leaves, wheat straws etc. up to a thickness of 5cm.
Step-5: After the construction of Vermibed, continuous watering is needed for the next 30 days. During this step, we need to keep in mind that the feed must not be dry or soggy.
Step-6: Then, cover the Vermibed with either coconut leaves or old gunny bags instead of plastic, to avoid the heat trapment. This step also helps against the attack by birds.
Step-7: Finally, spread the pre-digested organic debris up to the thickness of 5cm, and repeat this step twice a week.
After all these steps, turn over the organic debris via pickaxe or spade and allow regular watering. The production of humus-rich, granular and dark black coloured vermicompost usually takes 2-3 months.
The vermicompost is ready for harvesting when the earthworm’s excrement or castings are observable over the soil surface. During this stage, the worms and solid waste are separated manually.
For the separation of the earthworm and solid waste: Stop watering for 2-3 days, due to which, they will move towards the bottom of the bed. Then, subject the compost to the light treatment, after which the earthworms will migrate towards the cooler base. At last, eliminate the worm and the solid waste through sieves or meshes.
At the time of quality checking, the texture, colour, porosity, odour, moisture etc. are the parameters which are of importance. The vermicompost should have granular-texture, dark-black coloured, lightweight, earth-like smell and 40% of moisture content. A musty smell from the compost indicates the presence of mould or any lousy odour indicates the incomplete decomposition.
While packaging, the vermicompost is again sieved to ensure the elimination of any plant and animal remnants. Then the vermicompost is packaged into the laminated over sacs to avoid moisture loss and labelled with the brand’s name, nutritive facts, direction for use, market price etc. Finally, it is ready for the stage of marketing which targets over the people engaged in nurseries, farming, landscapers, gardeners etc.
Advantages of Vermicomposting
Vermicomposting is an Eco-biotechnological method having diverse benefits and applications in the following fields:
- Vermicompost improves the soil quality, structure and texture by providing a humus-rich environment.
- It also nourishes and conditions the soil by increasing water holding capacity and aeration.
- Vermicompost prevents the soil from draught and soil-erosion.
- Unlike chemical fertilizers, it does not harm the soil microbiota.
- Vermicompost promotes excellent growth of the plant by providing essential nutrients.
- It also helps in the germination and yield of the plant.
Food and crop improvement
- Vermicompost minimizes the prevalence of crop diseases by the different agents like pests, bacteria, mould etc.
- It promotes healthy living by producing bio-organic food, free of chemicals.
- Vermicompost reduces land pollution, by converting bio-waste into plant’s usable material from being discharged into the landfills.
- It curtails the emission of greenhouse gases (Methane, nitric oxide, etc.) produced from the landfills.
- It also reduces the demand for chemical fertilizers.
- Vermicompost acts as a medium for providing a supplemental source of income by employing individuals in rural areas.
- It requires low capital investment and simple technologies.
Disadvantages of Vermicomposting
Vermicomposting has few limitations also like:
- It requires more labour-power and skills for operation and maintenance of vermicompost.
- The vermicomposting method also needs more space for the construction, harvesting and storage methods in vermicomposting.
- Environmental factors like temperature, direct sunlight, drought may affect the process.
It also refers as “Vermicompost tea” and can define as a liquid extract obtained from the vermicompost. To prepare worm tea, take any old t-shirt, muslin cloth or tea bag, filled with vermicompost.
Then dip the bag into the bucket containing water for overnight. A light brown coloured solution will obtain that can transfer into the spray bottles. Worm tea helps in disease suppression by spraying the solution to the plant foliage.