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Vermicomposting PDF Print E-mail
Tuesday, 25 May 2010 12:16

Vermicomposting is the process of using earthworms and micro-organisms to convert kitchen waste into black, earthly- smelling, nutrient-rich humus. When worm compost is added to soil, it boosts the nutrients available to plants, enhances soil structure and drainage.

To Begin – You need five (5) basic ingredients to start vermicomposting:

  • Container
  • Bedding
  • Water
  • Worms
  • Non-fatty kitchen scraps

 

Containers

Worm boxes can be purchased or made. The boxes need to be shallow because the worms feed in the top layers of the bedding. A box that is too deep is not as efficient and could potentially become an odor problem. The boxes should have a depth of eight and twelve inches and of a manageable size. The larger the box, the heavier it becomes. We at the B.A.D.M.C made our worm boxes using wood from old wooden pallets to truly make it an ‘environmental experience’. The Extension Department of the B.A.D.M.C used the following dimensions to construct the boxes: depth- 12 inches, width 18 inches, length 24 inches.

Plastic type containers are also convenient to use and come in a variety of sizes. Depending on the size of the container, drill 8 to 12 holes (1/4”-1/2”diameter) in the bottom for aeration and drainage. Increase the amount of holes if drainage is inadequate.

The box/bin should be covered to conserve moisture and provide darkness for the worms. If the box/bin is indoors, a sheet of dark plastic or dry grass should be loosely placed on top of the bedding as a cover. For outdoor boxes/bins, a solid lid is preferable, to keep out unwanted scavengers and rain.

Raise the box/bin on bricks or wooden blocks and place a tray underneath to capture excess liquid which can be used as liquid plant fertilizer.

 

 wooden20box

 Wooden box

 

Bedding

The bedding for vermicomposting should be non toxic, fluffy material that holds moisture and allows air to circulate. Suitable materials include shredded paper (such as black and white news paper, paper bags, computer paper, or cardboard); composted animal manure (cow, horse, or rabbit); shredded decaying leaves; peat moss (which increases moisture retention); or any combination of these. Do not use glossy paper or magazines.
Add two handfuls of soil to supply roughage for the worms.
Adding crushed eggshells provides not only roughage but also calcium for the worms, and it lowers acidity in the box/bin.
The amount of bedding depends on the size of box. A 2’x 2’ box will need between 4 to 6 lbs of dry bedding, and 9 to 14 lbs of bedding should be used in a 2’by 3’box.
Regardless of the size, the box should be 2/3 filled with prepared bedding.
 

worm20bin

Picture illustrating layers of material in worm bin

(From top to bottom burlap/feed bag, dry straw, cornmeal, compost, dry grass and shredded newspaper)

 
Water

The bedding must be kept moist to enable worms to breathe. To keep bedding moist, irrigate daily using a watering can.

 

Worms 

The worms used in vermiculture are called redworms  (Eisenia foetida),  also known as red wrigglers, manure worms, red hybrid or tiger worms. These worms can be found  in decaying cow/horse manure. One lb redworms will easily take care of each ½ lb of garbage. To add worms to box/bin, simply scatter them over the top. The skin of the worm reacts to light and they will immediately work their way down into the bedding to get away from the light.
 

worms

Red Worms

 

Harvesting the compost

Given the right environment, the worms will go to work to digest the kitchen scraps and bedding faster than any other compost method. The material will pass through the worms’ bodies and become “castings”. In about 3-4 months, the worms will have digested nearly all the garbage and bedding in the box/bin will be filled with a rich, black natural fertilizer and soil amendment. Compared to ordinary soils, the worm castings contain five times more nitrogen, seven times more phosphorus and  eleven times more potassium. The castings are rich in humic acids and improve the structure of the soil.

To keep your box/bin going, you will need to remove the castings from time to time and there are several ways to achieve this. One way is to shine a bright light into the box/bin. The worms are sensitive to light and will move to the lower layers of the box/bin. Remove the top layer of casting by using your hands or a sieve. Each time you remove some bedding, the worms will be exposed to the light and they will keep migrating down to the bottom of the box/bin. Pick out any wrigglers or worm eggs (small, opaque cocoons) and return them to the box/bin. Refill the box/bin with fresh layers of moist bedding and food.

Another method of harvesting compost is to push the black, decomposed material to one side of the box/bin, and fill the other side with new, moist bedding and kitchen scraps. Then wait several days. The worms will migrate to the freshly filled side of the box/bin and you can just scoop out the finished compost. Make sure you pick out any wigglers or worm eggs and return them to the box/bin.   

 

Using the compost

For potted plants, add a thin layer to the top of the potting soil. You can also add the compost directly into your soil mix when repotting. In the garden, simply work it into the ground around the base of each plant. The compost is very mild and you won’t have to worry about accidental burning or over fertilizing.

 

Some Don’ts…

Don’t put plastic bags, bottle caps, rubber bands, sponges, aluminum foil and glass in the bin. These materials will be there for ever and make your worm box/bin look like trash.

Don’t let your cat use your worm box/bin as a litter box. First, cat urine will soon make the odor intolerable. Secondly, the ammonia in the urine could kill your worms. There is also a concern with toxoplasmosis, a disease that is of particular concern to a pregnant woman who may pass on the disease to her unborn child. If you have cats, provide a screen or other device to keep them from using the worm box/bin as a litter box.

Don’t use insecticides around your worm box/bin. You will not only take care of a few pests but also your worms.

Don’t use garden soil as bedding for the worms.

Don’t mix fresh cow, horse and especially chicken manure into your bedding. These manures will heat up the bedding and literally cook your worms.

 

Other Concerns

After you have established your worm box/bin, you may begin noticing other creatures besides the red worms. Most of these are helpful because they help breakdown the materials. These helpful creatures include millipedes.

There are also some creatures that may cause you problems. These would include centipedes, predatory mites, fruit flies, beetles and ants. Non-lethal methods of control (swatting, traps for fruit flies and ants, etc.) are the best for areas around your worm boxes/bins. Rodents are not a problem when the box is constructed and managed properly. 

 
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