Introduction
Earthworms have been on the Earth for over 20 million years. In this time they have faithfully done their part to keep the cycle of life continuously moving. Their purpose is simple but very important. They are nature’s way of recycling organic nutrients from dead tissues back to living organisms. Many have recognized the value of these worms. Ancient civilizations, including Greece and Egypt valued the role earthworms played in soil. The Egyptian Pharaoh, Cleopatra said, “Earthworms are sacred.” She recognized the important role the worms played in fertilizing the Nile Valley croplands after annual floods. Charles Darwin was intrigued by the worms and studied them for 39 years. Referring to an earthworm, Darwin said, “It may be doubted whether there are many other animals in the world which have played so important a part in the history of the world.” The earthworm is a natural resource of fertility and life.
Earthworms live in the soil and feed on decaying organic material. After digestion, the undigested material moves through the alimentary canal of the earthworm, a thin layer of oil is deposited on the castings. This layer erodes over a period of 2 months. So although the plant nutrients are immediately available, they are slowly released to last longer. The process in the alimentary canal of the earthworm transforms organic waste to natural fertilizer. The chemical changes that organic wastes undergo include deodorizing and neutralizing. This means that the pH of the castings is 7 (neutral) and the castings are odorless. The worm castings also contain bacteria, so the process is continued in the soil, and microbiological activity is promoted.
Vermicomposting is the process of turning organic debris into worm castings. The worm castings are very important to the fertility of the soil. The castings contain high amounts of nitrogen, potassium, phosphorus, calcium, and magnesium. Castings contain: 5 times the available nitrogen, 7 times the available potash, and 1 ½ times more calcium than found in good topsoil. Several researchers have demonstrated that earthworm castings have excellent aeration, porosity, structure, drainage, and moisture-holding capacity. The content of the earthworm castings, along with the natural tillage by the worms burrowing action, enhances the permeability of water in the soil. Worm castings can hold close to nine times their weight in water. “Vermiconversion,” or using earthworms to convert waste into soil additives, has been done on a relatively small scale for some time. A recommended rate of vermicompost application is 15-20 percent.
Vermicompost and its utilization
Vermicompost is nothing but the excreta of earthworms, which is rich in humus and nutrients. We can rear earthworms artificially in a brick tank or near the stem / trunk of trees (specially horticultural trees). By feeding these earthworms with biomass and watching properly the food (bio-mass) of earthworms, we can produce the required quantities of vermicompost.
Types of biodegradable wastes used:
1. Crop residues
2. Weed biomass
3. Vegetable waste
4. Leaf litter
5. Hotel refuse
6. Waste from agro-industries
7. Biodegradable portion of urban and rural wastes
2. Weed biomass
3. Vegetable waste
4. Leaf litter
5. Hotel refuse
6. Waste from agro-industries
7. Biodegradable portion of urban and rural wastes
Nutritive value of vermicompost
The nutrients content in vermicompost vary depending on the waste materials that is being used for compost preparation. If the waste materials are heterogeneous one, there will be wide range of nutrients available in the compost. If the waste materials are homogenous one, there will be only certain nutrients are available. The common available nutrients in vermicompost is as follows
Organic carbon | 9.5 – 17.98% |
Nitrogen | 0.5 – 1.50% |
Phosphorous | 0.1 – 0.30% |
Potassium | 0.15 – 0.56% |
Sodium | 0.06 – 0.30% |
Calcium and Magnesium | 22.67 to 47.60 meq/100g |
Copper | 2 – 9.50 mg kg-1 |
Iron | 2 – 9.30 mg kg-1 |
Zinc | 5.70 – 11.50 mg kg-1 |
Sulphur | 128 – 548 mg kg-1 |
Advantages of vermicompost
Vermicompost is rich in all essential plant nutrients.
Provides excellent effect on overall plant growth, encourages the growth of new
shoots / leaves and improves the quality and shelf life of the produce.
Vermicompost is free flowing, easy to apply, handle and store and does not have bad
odour.
It improves soil structure, texture, aeration, and waterholding capacity and prevents
soil erosion.
Vermicompost is rich in beneficial micro flora such as a fixers, P- solubilizers,
cellulose decomposing micro-flora etc in addition to improve soil environment.
Vermicompost contains earthworm cocoons and increases the population and
activity of earthworm in the soil.
It neutralizes the soil protection.
It prevents nutrient losses and increases the use efficiency of chemical fertilizers.
Vermicompost is free from pathogens, toxic elements, weed seeds etc.
Vermicompost minimizes the incidence of pest and diseases.
It enhances the decomposition of organic matter in soil.
It contains valuable vitamins, enzymes and hormones like auxins, gibberellins etc.
Storing and packing of vermicompost
The harvested vermicompost should be stored in dark, cool place. It should have minimum 40% moisture. Sunlight should not fall over the composted material. It will lead to loss of moisture and nutrient content. It is advocated that the harvested composted material is openly stored rather than packed in over sac. Packing can be done at the time of selling. If it is stored in open place, periodical sprinkling of water may be done to maintain moisture level and also to maintain beneficial microbial population. If the necessity comes to store the material, laminated over sac is used for packing. This will minimize the moisture evaporation loss. Vermicompost can be stored for one year without loss of its quality, if the moisture is maintained at 40% level.
The harvested vermicompost should be stored in dark, cool place. It should have minimum 40% moisture. Sunlight should not fall over the composted material. It will lead to loss of moisture and nutrient content. It is advocated that the harvested composted material is openly stored rather than packed in over sac. Packing can be done at the time of selling. If it is stored in open place, periodical sprinkling of water may be done to maintain moisture level and also to maintain beneficial microbial population. If the necessity comes to store the material, laminated over sac is used for packing. This will minimize the moisture evaporation loss. Vermicompost can be stored for one year without loss of its quality, if the moisture is maintained at 40% level.
