Vermicomposting is the process by which worms are used to convert organic material (usually wastes) into humus-like material known as vermicompost.
April will be an exciting month for EdibleScapes. We are planning on adding a vermicompost operation to the community composting site. This forward planning will ensure delivery of our first vermicast products by August at the Botanical Bazaar Gardening Expo.
The cultivation of earthworms in organic wastes has been termed vermiculture, and vermicomposting. Vermiculture is the culture of earthworms. Vermicomposting is the process by which worms are used to convert organic material (usually wastes) into humus-like material known as vermicompost. Our goal is to produce vermicompost, so we want to have maximum worm population density all the time.
The following guidelines should be followed: (Insert from the best practice guidelines, Appendix P-AS_4454.)
(a) Mixing and feedstock preparation: A homogeneous mix of feedstock material is of paramount importance to ensure consistent processing throughout the organic material.
(b) Dimensions: A minimum bed depth of mature vermicast of 0.3 to 0.4 m is recommended. The size of such beds is flexible, but the width should allow the entire bed to be inspected easily. The amount of fresh material added to the surface should not result in anaerobic conditions and heat generation. An important principle to improve the efficiency of processing of organic wastes by earthworms is to add the material to the beds in thin layers of 2.5 – 5.0 cm at frequent intervals. Compost worms are big eaters. Under ideal conditions, they are able to consume in excess of their body weight each day, although the general rule-of-thumb is ½ of their body weight per day.
(c) Ingredients: The optimum C:N ratio is approximately 20–25:1. Organic material high in available energy (low C:N) should be mixed with materials that are low in available energy (high C:N). This material should be uniformly mixed with the other ingredients. Size reduction of the various components of the feed mix assists in decomposition of the material and facilitates worm access. The resulting feed mix should be within a pH range of 5.5 to 8.5 and its electrical conductivity should not exceed 3 dS/m.
(d) Moisture: Optimum moisture levels vary between 80–90% in the active layer of the vermiculture system (where feedstock is supplied) and between 30–70% in the bed material.
(e) Temperature: Vermiculture systems operate best in a mesophilic bed temperature range of between 5 to 35°C, ideally 15 to 25°C.
(f) Oxygen: Worms require an aerobic environment of not less than 10% free oxygen in the active layer of the system.
(g) Duration: A minimum processing time of not less than six weeks is recommended to produce stabilized material. An additional maturation step of between 4 to 6 weeks may be required after removing the material from the system to achieve a greater level of maturity.
The Compost Worm: There are an estimated 1800 species of earthworm worldwide, some sources number more than 4000-5000 earthworm species. However, vermiculture/vermicomposting selects just 7 species, and the majority just focus on one. Eisenia fetida (Savigny) is commonly known as red Californian, compost worm, red wiggler or other local names.
Stocking density: Refers to the initial weight of worm biomass per unit area of bedding. For instance, if you started with 5kg of worms and put them in a bed with a surface area of 2m², then your initial stocking density would be 2.5 kg/m². The most common densities for vermicomposting are between 5 and 10 kg/ m². Worm growers tend to stock at 5 kg/m² and split the beds when the density has doubled, assuming that the optimum densities for reproduction have by that point been surpassed.
Composting and vermicomposting: A combination of composting and vermicomposting has recently been considered as a way of achieving stabilized substrates. Composting enables sanitization of the waste and elimination of toxic compounds, and the subsequent vermicomposting reduces particle size and increases nutrient availability; in addition, earthworms inoculate the material resulting from the thermophilic phase of composting.
It should be noted that pasteurizing temperatures cannot be achieved during vermicomposting processing as worms are sensitive to thermophilic (hot) temperatures. Thus, raw ingredients used in vermiculture systems should be relatively free of plant pathogens and plant propagules unless pre- or post-pasteurization is performed. This can be achieved through a composting process. This is the way EdibleScapes will feed the worms with mature compost pre-produced by the hot (thermophilic) composting process.
Compost and Vermicompost maturity: Both composting and vermicomposting transform fresh organic wastes into useful products that are rich in available nutrients for plant growth. Subjectively, a mature compost should be dark brown or black, with a granular, spongy, or fibrous texture, and smell like mould or soil. A mature vermicompost should also be dark black, usually finely divided peat-like material with excellent structure, porosity, aeration, and drainage properties and high moisture-holding capacity.
Compost and Vermicompost systems may be an alternate, inexpensive way to avoid environmental problems and at the same time obtain a valuable organic fertilizer. Vermicomposting may have an important role in organic waste management, and it is possible to suggest that vermicomposting and composting are not necessarily mutually exclusive and could be used in sequence to take advantage of the unique and valuable feature of each.
For EdibleScapes, vermicompost will be a valuable plant and tree fertiliser. We anticipate that vermicast surplus will bring much needed funds which are vital toward the future operational cost of the public edible landscape gardens, community composting demonstration learning site and EdibleScapes programs.
Update June - May 2019
a process of reproducing beneficial microorganisms, obtained from a natural forest.