The term vermicomposting means the use of earthworms for composting organic residues. Earthworms can consume practically all kinds of organic matter and they can eat their own body weight per day, e.g. 1 kg of worms can consume 1 kg of residues every day. The excreta (castings) of the worms are rich in nitrate, available forms of P, K, Ca and Mg. The passage of soil through earthworms promotes the growth of bacteria and actinomycetes. Actinomycetes thrive in the presence of worms and their content in worm casts is more than six times that in the original soil.
HOW TO PREPARE
Build or purchase a worm bin. The worm bin is the enclosure in which the worms will live; it holds in the bedding and food scraps, regulates the amount of moisture in the bedding, and blocks light (which is harmful to worms). Many gardening or organic supply stores sell pre-assembled worm bins, but it is cheap and easy to improvise one as well.
- Your worm bin can consist of a large plastic storage bin with a lid. The bin should be opaque to block light, and only about a foot (30 cm) deep, as worms prefer to live just under the soil’s surface. A typical family of 2 will need a bin with 4 square feet (.37 sq. m) of surface area; a family of 4 will need 8 square feet (.74 sq. m) of surface area.
- Drill several small holes in the sides of the bin for air flow. The worms won’t leave through these holes because of their aversion to light, but you can cover the holes with wire screen or mesh if desired.
Purchase worms for your vermicompost bin. The best types of worms to use in a vermicomposting operation are red wigglers (scientific name Eisenia Foetida). The earthworms that are typically found in outdoor soil don’t break down materials aggressively enough for indoor composting. The worms can be ordered from any number of organic gardening stores; they will come shipped in a mass of peat. Order a pound (.45 kg) of worms to begin your bin. They will reproduce quickly.
Prepare the worm bedding. The bedding is the material that the worms will live in. It can be made from any carbon-rich organic matter (such as paper or cardboard), but newspaper works the best. Tear the newspaper into long, 1 inch (25 mm) wide strips. You will need enough to fill the bin when packed loosely.
Moisten the bedding. Worms can only live in a moist environment, so you need to make sure the bedding is sufficiently moist. Begin by placing the newspaper strips into the worm bin. Pour in some water directly from your sink tap (bottled, dechlorinated water is better for the worms if available), and work it into the newspaper with your hands. When finished, the bedding should feel like a wrung-out sponge – if you squeeze it in your hands, no more than a drop or 2 of water should fall out.
Add a handful of soil to the bedding. In addition to the bedding, add a handful of soil from outdoors. The soil provides “grit” for the worms, which helps them digest your food scraps. It also introduces microorganisms into the worm bin that aid in decomposition.
Add the worms to the vermicompost bin. Add the worms by scattering them onto the bedding. Close the lid to block any light. Give the worms about a day without adding food scraps to work their way into the bedding.
Add food scraps to the bin. To begin composting, simply toss your food scraps into the worm bin and then reseal the lid. It helps to bury the scraps under a bit of bedding to prevent fruit flies from appearing. At first, you want to avoid overwhelming your worms with scraps. As time progresses, you can add more and more scraps.
Harvest the vermicompost. After removing the worms, you can remove the completed compost and store it for later use. Don’t worry if there is a bit of undigested bedding left in the compost, as it will break down fairly quickly.
Replace the bedding and re-introduce the worms. As the worms will have digested much of the bedding, it’s best to provide them with fresh bedding after harvesting the compost. Prepare the bin as before, and repeat the process
HOW TO USE
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|