Vermicomposting is one of the sustainable agriculture practices that follows the principles of organic farming.
It is a natural organic fertilizer prepared by using earthworms that convert organic compounds into manure.
Earthworms help to decompose complex organic matter by reducing the C: N ratio into manure. They enhance the soil exposed to the microorganisms, making it favorable for microbial activity and improving soil properties.
It is an environmentally friendly process that converts biodegradable matter into vermicast.
Vermicast is rich in nutrients that help in plant growth and inhibits harmful microbes in the soil. Thus it is called black gold. This is an ideal form of natural manure, which is easy to make and handle, economical and rich in nutrients.
Vermicompost is rich in humus, Nitrogen (2-3 %), Phosphorous ( 1.55-2.25%), Potassium ( 1.85-2.25 %), micronutrients and other beneficial soil microbes. Vermicompost increases the population of nitrogen-fixing bacteria and actinomycetes. Overall, it is an ideal form of an organic amendment to improve crop growth and yield.
Methods of vermicomposting
- Bed method- beds are made on the floor ( 6×2×2 feet). It is easy to maintain
- Pit method- composting is done in pits made of cement (5×5×3 feet). This method is rarely used.
Materials used for Vermicomposting
- Organic waste- kitchen waste, animal waste, farm waste ( cow dung and dried crop waste are mainly used). Always use both leguminous and non-leguminous crop waste for vermicomposting.
- Earthworms- Locally available earthworms and those found in soil show prolonged action. For quick action, specific earthworms are preferred.
- Cow dung
- Gunny bags
- Large bin (cemented or plastic tank)
The specific species of earthworms used for composting include
- Eisenia fetida (red wriggler worms)- these are mostly preferred due to their vigorous multiplication property.
- Eudrilluseuginiae ( African nightcrawler)
- Perionyx excavates
Process of Vermicomposting
- To prepare the vermicompost, plastic or concrete tank can be used according to the availability (Size- based on the quantity of raw materials available)
- Collect the dried biomass ( garden waste, animal waste, municipal waste, etc.) and chop them
- Mix the chopped dry material with cow dung in a 1:3 ratio and keep them aside for 15-20 days for partial decomposition
- Add a thin layer of soil /sand (2-3 inches) at the bottom of the tank.
- Now prepare the bedding by adding the partially decomposed cow dung and dried waste mixture. Distribute it evenly on the soil
- Continually add the mixture up to a depth of 0.5-1 foot.
- Now release the earthworms in the tank (1000-2000 earthworms / square meter). Cover the mixture with gunny bags/ straw/ plastic.
- Monitor the bin for the availability of food to the earthworms and add the food (fruit and vegetable peels, other kitchen waste) when necessary (make sure not to add excess food)
- Do watering regularly to maintain moisture.
- Monitor the composting tank to maintain temperature and moisture
- Beds should be turned in every 30 days for aeration and proper decomposition.
- Compost will be ready in 45-50 days.
Harvesting the compost
Earthworms eat the food and leave the excreta. Soft, black/brown colored component similar to humus is formed in the bin within 45-60 days. This is called worm casting/ vermicast/ vermicompost.
Collect the casting formed on the top layer. For collecting it, separate the earthworms and feed them. Earthworms will start their activities and continue with the process of vermicomposting. The castings can be collected once a week.
- The site should be cool, shady and moist.
- Biomass should be properly dried.
- Cow-dung should at least be 15-20 days old to avoid heat.
- Organic waste should be free from plastics, pesticides, metals, chemicals, and other toxic materials.
- Avoid adding dairy, ginger, meat, acidic foods like lemon, orange, citrus foods as feed for the earthworms.
- Proper aeration should be maintained for the growth and multiplication of earthworms.
- Optimum moisture should be maintained ( above 50 %, usually 70-80 % is considered as ideal)
- The Optimum temperature should be maintained (Temperature- 18-250C)
Application of vermicompost
The dosage of vermicompost is based on the crops we grow. For field crops, 5-6 tonnes/ ha vermicompost is applied.
For horticultural crops, it is advised to combine an equal amount of manure with vermicompost. In fruit crops, apply 4-5 kg of vermicompost per plant in the tree basin. Vermicompost can also be used in potted plants. 100-200 gm/ Pot is the ideal dosage for plants grown in pots.
Components derived from Vermicompost
Vermiwash- it is the excreta and mucus secretion of the earthworms. This can be collected when water is passed through the medium of the earthworm.
It is a pale yellowish liquid containing micronutrients from the organic matter in the medium. It also contains enzymes and secretions of earthworms, which aid in the growth of the plant.
Advantages of vermicompost
- Vermicompost helps improve soil structure, texture, porosity, water holding capacity, drainage, and aeration and reduce erosion.
- It improves plant growth by enabling the growth of new shoots and leaves, thereby increasing productivity.
- It helps to neutralize the pH of the soil.
- Vermicompost enhances the soil’s microbial activity and adds beneficial microbes, lowers the pest and disease incidence.
- It is easy to apply and handle, economical and does not have a foul odor.
- It is free from any pathogens or harmful materials.
- It contains several micro and macronutrients, vitamins, enzymes and hormones like auxins and gibberellins.
Disadvantages of Vermicompost
- Odor- If not done properly, it releases a bad odor. Filling the compost bin with green plants forms ammonia and produces the smell. Adding carbon sources like paper helps to neutralize the smell.
- Time- It is a time-consuming process and usually takes 2-3 months for completing the process
- Maintenance- Temperature needs to be maintained for better action by earthworms. The bad odor attracts rodents and flies. So, the bin should be covered properly.