Vermicomposting: Methods, Process, Mechanisms, Uses

Vermicomposting is an environmental biotechnology of conversion of organic household wastes to high nutrient value organic manure using earthworms.

• A process through which earthly worms eat and digest raw organic waste into nutrients in the soil.
• Thus, they are also called “worm-compost”, “worm-casting.” or even simply as vermicast..
• Vermicompost: Vermicompost from earthworms is the excrement of belabor and carries humus, microorganism hormones like auxins, enzymes including cellulases, chitinases, and proteases responsible for nitrogen mineralization in soil.
• In this process, breeding and raising earthworms in a controlled environment is the key and it is called Vermiculture.
• Vermi Technology is a mix of vermi culture and vermin compost
• The best organic farming tool as it releases valuable nutrients to the soil this helps a lot in maintaining and sustaining fertility status for a longer time without any adverse effects as compared to chemical fertilizers.

Methods of Vermicomposting

There are several methods of carrying out the process of Vermicomposting. Some of them are described below:

• Bin Method: Usually, in this technique, the process of vermicompost is done inside a closed container that has drainage and airflow arrangement. This kind of approach is being conducted on a micro-scale production space.
• Bed Method: A bed of wood or bricks is made on the ground surface where organic matter and earthworms are placed. On a production scale farm, the site is usually prepared by digging and shaping out beds or creating large trenched beds to accommodate big matters hence allowing plenty of room.
• Pit Method: In this method, a trenched shallow pit is made and the organic waste along with worms are entered into it. After that, it is covered with some organic matter like grass- straw, and dry leaves of trees to keep in check the temperature as well as moisture.
•  Heap Method: In this method, organic wastes and worms are kept in a heap directly onto the ground level layered with straw or other materials like dry leaves, etc. This is the classic form of composting.

Materials Required in Vermicomposting

• Land
• Water
• Sand/soil
• Biodegradable Agricultural wastes.
• Shredded Papers/Cardboards
• Cow Dung
• Poultry Litters
• Shade
• Straw and dried leaves
• Pit/container
• Gunny Bags
• Earthworms

Process of Vermicomposting

The method of vermicomposting may vary but the process involved in all of them are the same as follows:

Vermicomposting Site Selection

• Selecting a site that is free or protected from the harsh weather
• The site should have enough space for the feedstock.
• A dependable source of water must be there.
• The environment of the site must encourage the survival and propagation of worms.

Manure Stockpiles Preparation

• Dried manure is placed in the designated site or area.
• The unwanted matter like stones, thorns, weeds, etc is removed.
• Ensure everything is chopped or ground (less than 10mm) so it can be handled efficiently with manure for organic matter.

Pre-decomposition of Feedstock

• The stockpiles prepared need to be pre-decomposed before introducing them to the earthworms.

Preparation of Vermicomposting Beds

•  Raised windows of 1.2m-1.5m wide x 0.3m high were constructed on the brick beds along with the drainage holes.
• Then the soil or ground surface is moistened thoroughly.
• The bed is layered with dry plant products like wood chops, dry leaves, or grass along with the 20mm layer of neem leaves followed by 0.3mm manure for better air circulation.

Materials Moistening

• Sprinkling the water after each layering is a very important role that activates the initial decomposition of the materials.
• If the materials are too dried, they are soaked in 100-200 liters of water before bedding.

Earthworm Introduction

• The earthworms are introduced 5-10cm below the bed surface.
• Then they are covered with straw, broad leaves plants, or gunny bags which will block the sunlight and provide the cooling effect on the Vermin bed.

Maintenance of Vermicompost System

• The Vermin bed prepared must be watered two to three times a week.
• Also turning the materials of the bed, every two to three times a month is necessary for the maturation of compost.

Harvesting Vermicompost

• In 2-3 months depending upon on the size of the area and the number of worms introduced in the vermicomposting.
• Before Harvesting the compost, watering must be stopped to allow the top part of the manure to dry.
• The un-decomposed materials and worms must be removed and, then the end product must be dried separately for a few days.

Earthworm species used in Vermicomposting

Selection of the right species of earthworm is very important for vermicomposting. The whole process depends mainly on the vermiculture as their casting is our end product. The nutrient value of vermicompost depends upon species and their feed types. Thus there has been increased attention on the Eisenia fetida and Eudrilus eugeniae from the Epigeic Species of earthworms These are red wrigglers earthworms known as surface feeders. Both are potential agents that have been widely used in Vermicomposting technology because of their characteristics. They grow at a wide range of temperature varying from 0 – 40 °C. However, the optimum temperature ranges from 20- 30°C which helps in rapid growth and maturation. These earthworms have a high rate of organic matter consumption, digestion, and assimilation. They have a high environmental stress tolerance rate compared to the other species of earthworms. And lastly, the shorter life cycle of this species also prioritizes their preference for vermicomposting over other species of earthworms.

These worms are introduced at the rate of 3000 to 4000 numbers per bed size of one square meter.

Characteristics comparison of different earthworm species for the vermicomposting process

Optimal Conditions for Earthworms in Composting Materials

• Moisture: 60-70% of the moisture below and above range worms death occurs.
• Aeration: 50% Aeration from the total pore space
• Temperature: Range between 18°C to 35°C; insulation provision in case the temperature drops to freezing point.
• pH: must Range between 6.5 and 7.5
• The red worms can consume their body weight in the form of available organic matter within a day provided with suitable conditions.
• However, on average, it will take around 2 Kg of earthworms to complete the recycling of 1 kg of organic waste within a frame of 24 hours. 
• The worms within the top moist layer of bedding would disappear within minutes into the bedding.

Mechanisms of Vermicomposting

• When worms eat these foods, the material passes through their digestive system in a different form.
• Gizzard ≤2 μ particles after pulverization, providing hence a larger microbial surface area processing. 
• This ground output material is then exposed through protease/lipase/amylase to digest different proteins, lipids, carbohydrates
• In the gut cellulase and chitinase are liberated into the lumen wall with associated microbes and these enzymes break down complex large to simpler compounds. 
• All are cast aside —the worms in their growing and halting.
• Additionally, the mucus secretions of the gut wall further enhance local protection. stability of vermicompost.

Harvesting of Vermicompost

After a few months, the worm casting collected needs to be harvested from the compost. The casting is several inches deep, which appears to be dark brown, crumbling, earthy kinds of stuff. The earthworms must be removed while harvesting the manure, while some may remain despite the screening which causes no problem. Also, we can find the worm’s eggs during harvesting. These eggs are lemon-shaped, white to brown in color. If possible, these eggs also need to be removed as they can further be used for the next batch of vermiculture. The formed vermin-casting can be harvested in the following ways:

The Food Migration Method

The entire composting is shifted to one end of the bedding and fresh bedding is prepared on the other side. Put the worm food on one side of new bedding and after one week or so worms move to the other side for their feeding. The casting remains are harvested after the worms have been moved to the other side of the bedding.

The Light Method

Earthworms especially red wrigglers are light sensitive. They are buried down when exposed to light thus the bedding layer can be removed and when they move deep inside the compost we can collect the casting with light hands and keep on repeating the process until a marginal amount of the compost is harvested.

Storage of Vermicompost

After harvesting the compost, the storage of vermicomposting is the crucial aspect of maintaining the balanced physical, chemical, and microbiological properties of vermicompost. We must ensure to store it in a proper breathable container like cardboard, wooden crates, or a sack maintaining a moisture content of 40-60% at optimum temperature by placing it in a cool and dry space. And most importantly all materials used and space of storage must be sterilized to avoid the cross-contamination of microorganisms. If stored properly the compost’s quality, nutrient content, shelf life, and microbial activity won’t be compromised.

Characteristics of vermicompost

Physical Characteristics:

• Soft
• Spongy
• Earthy smell
• Dark brown color

Chemical Characteristics:

pH:7.6 

Microbiological Characteristics:

• Total Bacterial Count: more than 10^10
• Microorganisms Present: Actinomycetes, Fungi, AzetoBacter, Rhizobium

Precautions to be taken for Vermicomposting

• Using plastic sheets to cover beds/heaps is not recommended because it may create a greenhouse effect causing air and gases to entrap in the vermicompost bed/heap.
• However overloading them can increase their temperature, which is harmful to the worms.
• The worms die out in the dry conditions and they simply move away when the ground becomes waterlogged.
• In June, July, and August during summer daily watering is ideal while in the rainy season (December to February) once a week whereas in winter every third day.
• Do not add more acidic substances to the compost pile, such as tomatoes and citrus wastes.
• In rainy weather, this can avoid the accumulation of water, and especially in areas with high rainfall during that season you will need to build a drainage channel around the heap.
• Composting materials are organic as they can easily decompose and the process will be free from non-degradable materials such as stones, glass pieces, plastics, etc.

Significance of Vermicomposting

• The balanced physical, chemical, and microbiological characteristics make Vermi castings an excellent natural plant fertilizer since it is good for improving soil structure, moisture retention, and nutrient content.
• Vermicomposting promotes Organic farming in gardening and sustainable agriculture.
• It is an ideal replacement for chemical pesticides and insecticides.
• Vermicomposting leads to the highest crop yields when the plants grow, crops require a balanced amount of critical macronutrients and micronutrients through their growth cycle terminal for the highest yields, thus the nutrients present assure it.
• It is free-flowing and easy to apply on the field thus, the farmers or the users can handle it easily without any fiasco.
• It has also a growing emphasis on environmental conservation and waste recycling, so it is environmentally friendly.
• It can be done in domestic households on a small scale as it does not require fancy setups, a person can easily convert their house’s organic waste into valuable compost, which generates a positive outlook for a source of income.
• Now globally food security has been pushed or encouraged, so that the compost is free of toxins when used in the agriculture field gives toxin and chemical-free vegetable and fruit items.

References

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