Vermicompost ( vermi-compost) is the product of the decomposition process using various species of , usually Eisenia foetida, white worms, and other , to create a mixture of decomposing vegetable or food waste, bedding materials, and vermicast. This process is called vermicomposting, with the rearing of worms for this purpose is called vermiculture.
Vermicast (also called worm castings, worm humus, worm poop, worm manure, or worm faeces) is the end-product of the breakdown of organic matter by earthworms. These excreta have been shown to contain reduced levels of contaminants and a higher saturation of nutrients than the organic materials before vermicomposting.
Vermicompost contains water-soluble nutrients which may be extracted as vermiwash and is an excellent, nutrient-rich organic fertilizer and soil conditioner.Coyne, Kelly and Erik Knutzen. The Urban Homestead: Your Guide to Self-Sufficient Living in the Heart of the City. Port Townsend: Process Self Reliance Series, 2008. It is used in gardening and sustainable, organic farming.
Vermicomposting can also be applied for treatment of sewage. A variation of the process is Vermifilter (or vermidigestion) which is used to remove organic matter, pathogens, and oxygen demand from wastewater or directly from blackwater of flush toilets.
The earthworm species (or composting worms) most often used are red wigglers ( Eisenia fetida or Eisenia andrei), though European nightcrawlers ( Eisenia hortensis, synonym Dendrobaena veneta) and red earthworm ( Lumbricus rubellus) could also be used. Red wigglers are recommended by most vermicomposting experts, as they have some of the best appetites and breed very quickly. Users refer to European nightcrawlers by a variety of other names, including dendrobaenas, dendras, Dutch nightcrawlers, and Belgian nightcrawlers.
Containing water-soluble nutrients, vermicompost is a nutrient-rich organic fertilizer and soil conditioner in a form that is relatively easy for plants to absorb. Worm castings are sometimes used as an organic fertilizer. Because the earthworms grind and uniformly mix minerals in simple forms, plants need only minimal effort to obtain them. The worms' digestive systems create environments that allow certain species of microbes to thrive to help create a "living" soil environment for plants.
Vermicomposting is a common practice in permaculture.
Vermiwash can also be obtained from the liquid potion of vermicompost. Vermiwash is found to contain enzyme cocktail of proteases, amylases, urease and phosphatase. Microbiological study of vermiwash reveals that it contains nitrogen-fixing bacteria like Azotobactrer sp., Agrobacterium sp. and Rhizobium sp. and some phosphate solublizing bacteria. Laboratory scale trial shows effectiveness of vermiwash on plant growth.
These species commonly are found in organic-rich soils throughout Europe and North America and live in rotting vegetation, compost, and manure piles. As they are shallow-dwelling and feed on decomposing plant matter in the soil, they adapt easily to live on food or plant waste in the confines of a worm bin. Some species are considered invasive species in some areas, so they should be avoided (see earthworms as invasive species for a list).
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.
The following species are not recommended:
There are two main methods of large-scale vermicomposting, windrow composting and raised bed. Some systems use a windrow, which consists of organic feedstock for the earthworms to feed on. Earthworms will move into the windrows and remain within them as long as conditions are favourable; typically involving a balanced mix of feedstock, appropriate moisture content and a comfortable temperature. Often windrows are used on a concrete surface to control and manage leachate.
The world's largest vermicomposting operation by volume is MyNoke, a New Zealand-based operation that'
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Windrow turners were developed by Fletcher Sims Jr. of the Compost Corporation in Canyon, Texas. The Windrow Composting system is noted as a sustainable, cost-efficient way for farmers to manage dairy waste.
The second type of large-scale vermicomposting system is the raised bed or flow-through system. Here the worms are fed an inch of "worm chow" across the top of the bed, and an inch of castings are harvested from below by pulling a breaker bar across the large mesh screen which forms the base of the bed.
Because red worms are surface dwellers constantly moving towards the new food source, the flow-through system eliminates the need to separate worms from the castings before packaging. Flow-through systems are well suited to indoor facilities, making them the preferred choice for operations in colder climates.
Some materials are less desirable than others in worm bin construction. Metal containers often conduct heat too readily, are prone to rusting, and may release heavy metals into the vermicompost. Styrofoam containers may release chemicals into the organic material. Some Cedrus, yellow cedar, and Coast Redwood contain resinous oils that may harm worms, although western red cedar has excellent longevity in composting conditions. Tsuga is another inexpensive and fairly rot-resistant wood species that may be used to build worm bins.[1]
Bins need holes or mesh for aeration. Some people add a spout or holes in the bottom for excess liquid to drain into a tray for collection. The most common materials used are plastic: recycled polyethylene and polypropylene and wood. Worm compost bins made from plastic are ideal, but require more drainage than wooden ones because they are non-absorbent. However, wooden bins will eventually decay and need to be replaced.
Small-scale vermicomposting is well-suited to turn kitchen waste into high-quality , where space is limited. Worms can decompose organic matter without the additional human physical effort (turning the bin) that composting requires.
Composting worms which are Detritivore (eaters of trash), such as the red wiggler Eisenia fetida, are epigeic (surface dwellers) and together with symbiotic associated microbes are the ideal vectors for decomposing food waste. Common earthworms such as Lumbricus terrestris are anecic (deep burrowing) species and hence unsuitable for use in a closed system. Other soil species that contribute include , other worms and molds.
The most common worms used in composting systems, redworms ( Eisenia foetida, Eisenia andrei, and Lumbricus rubellus) feed most rapidly at temperatures of . They can survive at . Temperatures above may harm them.Appelhof, p. 3 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.Appelhof, p. 41 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.
The pyramid method of harvesting worm compost is commonly used in small-scale vermicomposting, and is considered the simplest method for single layer bins. In this process, compost is separated into large clumps, which is placed back into composting for further breakdown, and lighter compost, with which the rest of the process continues. This lighter mix is placed into small piles on a tarp under the sunlight. The worms instinctively burrow to the bottom of the pile. After a few minutes, the top of the pyramid is removed repeatedly, until the worms are again visible. This repeats until the mound is composed mostly of worms.
When harvesting the compost, it is possible to separate eggs and cocoons and return them to the bin, thereby ensuring new worms are hatched. Cocoons are small, lemon-shaped yellowish objects that can usually be seen with the naked eye. The cocoons can hold up to 20 worms (though 2–3 is most common). Cocoons can lay dormant for as long as two years if conditions are not conducive for hatching.
However, in one study it has been found that homemade backyard vermicompost was lower in microbial biomass, soil microbial activity, and yield of a species of ryegrass than municipal compost.
It is rich in microbial life which converts nutrients already present in the soil into plant-available forms.
Unlike other compost, worm castings also contain mucus which helps prevent nutrients from washing away with the first watering and holds moisture better than plain soil.Nancarrow, Loren; Taylor, Janet Hogan (1998). The Worm Book: The Complete Guide to Gardening and Composting with Worms Ten Speed Press. p. 4. .
Increases in the total nitrogen content in vermicompost, an increase in available nitrogen and phosphorus, a decrease in potassium, as well as the increased removal of heavy metals from sludge and soil have been reported. The reduction in the bioavailability of heavy metals has been observed in a number of studies.
Plant growth
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Environmental
The light brown waste liquid, or leachate, that drains into the bottom of some vermicomposting systems is not to be confused with worm tea. It is an uncomposted byproduct from when water-rich foods break down and may contain pathogens and toxins. It is best discarded or applied back to the bin when added moisture is needed for further processing.
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.
Predatory ants can be a problem in African countries.
In warm weather, fruit and vinegar flies breed in the bins if fruit and vegetable waste is not thoroughly covered with bedding. This problem can be avoided by thoroughly covering the waste by at least of bedding. Maintaining the correct pH (close to neutral) and water content of the bin (just enough water where squeezed bedding drips a couple of drops) can help avoid these pests as well.
In order to avoid over-fertilization issues, such as nitrogen burn, vermicompost can be diluted as a tea 50:50 with water, or as a solid can be mixed in 50:50 with potting soil.
Additionally, the mucous layer created by worms which surrounds their castings allows for a "time release" effect, meaning not all nutrients are released at once. This also reduces the risk of burning the plants, as is common with the use and overuse of commercial fertilizers.
From 20 July 2020, the State Government of Chhattisgarh India started buying cow dung under the "Godhan Nyay Yojana" Scheme. Cow dung procured under this scheme will be utilised for the production of vermicompost fertilizer.
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