Vermicompost is the product or process of composting using various worms, usually red wigglers, white worms, and other earthworms, to create a heterogeneous mixture of decomposing vegetable or food waste, bedding materials, and vermicast. Vermicast, also called worm castings, worm humus or worm manure, is the end-product of the breakdown of organic matter by an earthworm. These castings have been shown to contain reduced levels of contaminants and a higher saturation of nutrients than do organic materials before vermicomposting.Containing water-soluble nutrients, vermicomposting is an excellent, nutrient-rich organic fertilizer and soil conditioner. This process of producing Vermicompost is called vermicomposting.While vermicomposting is generally known as a nutrient rich source of organic compost used in farming and small scale sustainable, organic farming, the process of vermicasting is undergoing research as a treatment for organic waste in sewage and wastewater plants around the world.
- Red Wiggler (Eisenia fetida or Eisenia andrei)
- Lumbricus rubellus (a.k.a. red earthworm or dilong (China)
- European nightcrawlers (Eisenia hortensis)
- African Nightcrawlers (Eudrilus eugeniae
- Lumbricus terrestris (a.k.a. Canadian nightcrawlers (US)
- Blueworms (Perionyx excavatus)
- These species commonly are found in organic-rich soils throughout Europe and North America and live in rotting vegetation, compost, and manure piles. They may be an invasive species in some areas. As they are shallow-dwelling and feed on decomposing plant matter in the soil, they adapt easily to living on food or plant waste in the confines of a worm bin.
- Composting worms are available to order online, from nursery mail-order suppliers or angling shops where they are sold as bait. They can also be collected from compost and manure piles. These species are not the same worms that are found in ordinary soil or on pavement when the soil is flooded by water.
Climate and temperature
- The most common worms used in composting systems, redworms (Eisenia foetida, Eisenia andrei, and Lumbricus rubellus) feed most rapidly at temperatures of 15–25 °C (59-77 °F). They can survive at 10 °C (50 °F).
- Temperatures above 30 °C (86 °F) may harm them. This temperature range means that indoor vermicomposting with redworms is possible in all but tropical climates. (Other worms like Perionyx excavatus are suitable for warmer climates.)
- If a worm bin is kept outside, it should be placed in a sheltered position away from direct sunlight and insulated against frost in winter.
- There may be differences in vermicomposting methods depending on the climate.
- It is necessary to monitor the temperatures of large-scale bin systems (which can have high heat-retentive properties), as the feedstock used can compost, heating up the worm bins as they decay and killing the worms.
Small-scale or home systems
- Such systems usually use kitchen and garden waste, using “earthworms and other microorganisms to digest organic wastes, such as kitchen scraps”. This includes:
- All fruits and vegetables (including citrus and other “high acid” foods)
- Vegetable and fruit peels and ends
- Coffee grounds and filters
- Tea bags (even those with high tannin levels)
- Grains such as bread, cracker and cereal (including moldy and stale)
- Eggshells (rinsed off)
- Leaves and grass clippings
Large-scale or commercial
- Such vermicomposting systems need reliable sources of large quantities of food. Systems presently operating use:
- Dairy cow or pig manure
- Sewage sludge
- Brewery waste
- Cotton mill waste
- Agricultural waste
- Food processing and grocery waste
- Cafeteria waste
- Grass clippings and wood chips
- Attracts deep-burrowing earthworms already present in the soil
- Improves water holding capacity
- Enhances germination, plant growth, and crop yield
- Improves root growth and structure
- Creates low-skill jobs at local level
- Low capital investment and relatively simple technologies make vermicomposting practical for less-developed agricultural regions
- Vermicompost can be mixed directly into the soil, or steeped in water and made into a worm tea by mixing some vermicompost in water, bubbling in oxygen with a small air pump, and steeping for a number of hours or days.
- The microbial activity of the compost is greater if it is aerated during this period. The resulting liquid is used as a fertilizer or sprayed on the plants.
- The dark brown waste liquid, or leachate, that drains into the bottom of some vermicomposting systems as water-rich foods break down, is best applied back to the bin when added moisture is needed due to the possibility of phytotoxin content and organic acids that may be toxic to plants.
- The pH, nutrient, and microbial content of these fertilizers varies upon the inputs fed to worms. Pulverized limestone, or calcium carbonate can be added to the system to raise the pH.