Vermicasting, also called vermicomposting, is the processing of organic wastes through earthworms. It is a natural, odourless, aerobic process, much different from traditional composting. Earthworms ingest waste then excrete casts – dark, odourless, nutrient- and organically rich, soil mud granules that make an excellent soil conditioner. Earthworm casts are a ready-to-use fertilizer that can be used at a higher rate of application than compost, since nutrients are released at rates that growing plants prefer.
Vermicasting can be done on a small scale by homeowners with household organic wastes, on a large-scale by farmers with manure or by the food industry using organic wastes such as fruit and vegetable cull materials. Through proper design, vermicasting is a method of waste handling that:
is clean, socially acceptable, with little to no odour
requires no energy input for aeration
reduces the mass of waste by 30%
produces a valuable vermicast byproduct
even generates worms as fishing bait
Important Facts About Vermicasting
Turning organic wastes into casts takes 22–32 days, depending on density of waste and earthworm maturity (regular composting requires 30–40 days, followed by 3–4 months curing).
Vermicast does not need curing, but fresh casts undergo 2 weeks of nitrification where ammonium transforms to nitrate, a form that plants can uptake.
Use organic materials that meet the earthworm's feed preferences, including a material density of 350–650 g/L.
Worms should not be crowded, so the ideal stocking density is 150 earthworms/L of wastes.
Earthworms ingest about 75% of their body weight/day; a 0.2 g worm eats about 0.15 g/day.
If you discover earthworms trying to escape any system, it is a good indication that something is wrong with their feed or environment
Earthworms should be allowed about 1 week to migrate from finished vermicast to fresh waste.