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Redworms in vermicompost act in a similar fashion, breaking down food wastes and other organic residues into nutrient-rich compost. Nutrients in vermicompost are often much higher than traditional garden compost (see table 1).

Table 1. Chemical characteristics of garden compost and vermicompost, 1994.
Garden compost1
pH 7.80 6.80
EC (mmhos/cm)** 3.60 11.70
Total Kjeldahl nitrogen(%)*** 0.80 1.94
Nitrate nitrogen (ppm)**** 156.50 902.20
Phosphorous (%) 0.35 0.47
Potassium (%) 0.48 0.70
Calcium (%) 2.27 4.40
Sodium (%) < .01 0.02
Magnesium (%) 0.57 0.46
Iron (ppm) 11690.00 7563.00
Zinc (ppm) 128.00 278.00
Manganese (ppm) 414.00 475.00
Copper (ppm) 17.00 27.00
Boron (ppm) 25.00 34.00
Aluminum (ppm) 7380.00 7012.00
1Albuquerque sample 2Tijeras sample

* Units- ppm=parts per million mmhos/cm=millimhos per centimeter
** EC = electrical conductivity is a measure (millimhos per centimeter) of the relative salinity of soil or the amount of soluble salts it contains.
*** Kjeldahl nitrogen = is a measure of the total percentage of nitrogen in the sample including that in the organic matter.
**** Nitrate nitrogen = that nitrogen in the sample that is immediately available for plant uptake by the roots.

Finished vermicompost should have a rich, earthly smell if properly processed by worms. Vermicompost can be used in potting soil mixes for house plants and as a top dressing for lawns. Screened vermicompost combined with potting soil mixes make an excellent medium for starting young seedlings. Vermicompost also makes an excellent mulch and soil conditioner for the home garden.

How to Construct a Worm Bin

Bins can be made of wood or plastic, or from recycled containers like old bathtubs, barrels, or trunks. They also can be located inside or outside, depending on your preferences and circumstances.

As red wigglers tend to be surface feeders, bins should be no more than 8 to 12 inches deep. Bedding and food wastes tend to pack down in deeper bins, forcing air out. Resulting anaerobic conditions can cause foul odors and death of the worms.

The length and width of the bin will depend on whether it is to be stationary or portable. It also depends on the amount of food waste your family produces each week. A good rule of thumb is to provide one square foot of surface area per pound of waste in your bin.

Wooden bins have the advantage that they're more absorbent and provide better insulation. Do not use redwood or other highly aromatic woods that may kill the worms. Plastic tends to keep the compost too moist. Plastic, however, tends to be less messy and easier to maintain. Be sure containers are well cleaned and have never stored pesticides or other chemicals. Drilling air/drainage holes (1/4- to 1/2-inch diameter) in the bottom and sides of the bin will ensure good water drainage and air circulation. Place the bin on bricks or wooden blocks in a tray to catch excess water that drains from the bin. The resulting compost tea can be used as a liquid fertilizer around the home landscape.


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