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Thread: Projek Cinta: African Night Crawler - Windrow method of vermicomposting

  1. #1
    Join Date
    Oct 2008

    Projek Cinta: African Night Crawler - Windrow method of vermicomposting

    K.I.S.S. Plan for Organic Farms, Dairies,
    or Other Large-Scale Operations

    SUMMARY: The K.I.S.S. - Keep It Simple & Save - plan for vermicomposting for farmers and others uses established methods (an extended windrow) and available equipment (a front end loader) to process large volumes of organic material into vermicompost. The plan suggests easy, appropriate technology to manage environmental factors and control quality. The KISS plan is based on several years of research and experience in vermiculture and vermicomposting. The plan may be adapted to other situations or applications.

    Farmers and others will benefit from several advantages of this method:
    - It is simple; no special training is required.Low, low, low start-up cost—it uses existing equipment and available space. No turning, no odors—the orms do all the processing, naturally.
    - The resulting vermicompost, rich in worm castings, is more valuable to farmers, landscapers, and home gardeners than raw manure. It provides stable organic matter, conserves moisture, improves soil conditions in many ways, and enhances the growth and yields of most types of plants. (Current market value is upwards of $30-$90 per cubic yard.)

    STEP 1: WINDROW PREPARATION A windrow is a long row of material (e.g., 4 to 10 feet wide, by 2 to 3 feet high, by some appropriate length). The length can vary depending on the availability of gently sloping space, ease of material handling, or other factors. Longer windrows will cost a little more for supplies.

    To start a windrow, spread a 12 to 18 inch layer of manure solids, with or without bedding, along one end of your available space. Inoculate the windrow with high-quality redworms—Eisenia fetida (from a breeding or active pile). For this first row, apply up to 1 lb. redworms per sq. ft. of windrow surface area. Add 2 to 3 inch layers of manure every week (3 to 6 inch layers in colder weather) to gradually increase the depth of the windrow. Each windrow should be large enough to handle these thin layers of material each week. With a thermometer, make sure that the layers of feed do not get hotter than 35°C (95°F).

    Remember the following: This plan is for farm-scale volumes of manure or other suitable organic material. Larger volumes can help protect the worms from adverse conditions and predators. Enclosed bins are still recommended for home- or school-based vermicomposting.

    A hard or concrete surface is easier to work on, especially in wet weather, and may even be required to control runoff. As you extend the windrow (Step 2), leave a way to reach the finished castings.

    This method does not generate high heat. This is acceptable for many types of dairy and horse manure. If heat treatment is needed to control pathogens or weeds, simply pre-compost the material before feeding it to the worms.

    STEP 2: EXTENDING THE WINDROW After the first windrow is established and layered to around 2 to 3 feet thick, it is time to extend the windrow. Add the next layers of manure along one side, directly next to and against, the first windrow. The worms in the first pile will gradually migrate toward the fresher feed. Continue adding the fresh manure alongside until you have formed a second complete windrow. Repeat this step, extending the number of windrows to the limits of your need or space. The worms will continue migrating laterally through the windrows, leaving rich vermicompost in their wake.

    STEP 3: MAKING QUALITY CASTINGS Redworms tolerate a range of environmental conditions before suffering serious losses. Nonetheless, providing the optimum conditions for worm health and growth can assure maximum decomposition and transformation of organic wastes. Research from around the world and practical considerations suggest the following optimum conditions for redworms:

      • - Temperature: 15 to 20°C (60 to 70°F) Moisture content: 65 to 80 percent Oxygen requirement: aerobicity
        - pH: > 5 and < 9

    Keep the worms well fed and comfortable, and they’ll make quality castings in the decomposed manure/bedding. Their active burrowing habits naturally aerate the windrows, providing good control of odors. Leaving each windrow for a little longer time before harvesting assures the vermicompost will be more broken down, more stable, and have more worm castings present.

    STEP 4: MOISTURE AND IRRIGATION Moisture is also critical to the well being of your working worms. A simple method for applying moisture on a farm is through a sprinkling hose or other sprinkling/misting irrigation system. Run it the length of your windrow. Try to moisten evenly, i.e., keep the surface moist, but don’t let the bottom become soggy.

    STEP 5: WINDROW COVER A suitable compost cover, placed over the active windrow, is critical to preserving valuable nutrients in the vermicompost. Rather than nutrients leaching out and possibly contaminating ground or surface waters, they should be retained in the vermicompost in ways that are valuable for plants. Various types of tarps or fabrics could be used to shed excess rainfall and prevent leaching, while maintaining aerobic conditions. A few companies advertise fabric covers for composting. They may also be useful for vermicomposting. They include:

    • Compogard Cover, from W.L. Gore & Associates, Inc.,
      Elkton, MD, 410-392-3300

    Covering the windrows of finished castings prior to use also retains nutrients and helps prevent weeds from spreading.


    Because the worms concentrate in the freshest, most active windrow, after 2 to 6 months the first windrow and each subsequent windrow will become ready to use. It can be spread with a loader or manure spreader. Coarse material, if any, can be screened out to produce a fine, marketable soil amendment.

    © 1997 by Jim Jensen
    Permission granted to copy or post with complete attribution in whole.

    © 2008 Happy D Ranch
    The above content is the exclusive intellectual property of Happy D Ranch. Though it is permissible to print articles for personal educational use, they may not be replicated in part or whole in any form without obtaining our written permission. Individuals, groups or businesses infringing upon this copyright will be prosecuted to the fullest extent of the law. Images and articles that are not Happy D Ranch originals have been used by permission.


  2. #2
    Join Date
    Oct 2008
    OVERVIEW: The KISS (Keep It Simple & Save) plan for vermicomposting integrates established farming methods with new farming technologies to process and convert large volumes of compost into vermicompost.

    The primary focus of the plan uses a proven method to save farmers both time and money without compromising the quality of the final end product.
    BENEFITS: Both farmers and consumers benefit when following this proven method to convert organic materials to vermicompost:

    • Straightforward, simple approach that requires minimal training.
    • Start-up costs are minimal and your existing equipment can be utilized to begin the process right away.

    • The worm’s process and convert organic compost to vermicompost naturally in a relatively short period of time. There’s little or no turning and no foul odors.
    • The end product (vermicompost) is extremely rich in worm castings. Worm castings are far more valuable to farmers, landscapers and home gardeners than raw manure. Vermicompost provides rich organic matter which conserves water, supports a thriving ecosystems and ultimately results in faster growth with higher yields for most types of plants. The market value for vermicompost ranges from $29-$89 per cubic yard.

    To create a windrow, spread a 1-foot layer of manure with bedding across one end of the available space you’re working with. Add (inoculate) high quality Red Worms to the windrow. We suggest you add 16 oz. of Red Worms per square foot of windrow surface area. Add 3” layers of manure every week (up to 5” during winter months) to increase the depth of the windrow. All windrows should be big enough to handle new layers of material every seven days. As you monitor the windrows, make sure the temperature doesn’t exceed 92°F.
    Keep the following in mind:
    • This KISS plan is for processing large-scale quantities of manure. By using larger volumes, worms are protected from harsh weather conditions and predators. If you intend to create vermicompost for your home or small-scale testing, we recommended using composting bins.
    • It’s recommended you use a concrete surface as opposed to dirt or other materials. During wet weather, you should have a surface that can easily divert water runoff, to aid in maintaining an optimal moisture level for your worm population. Too much moisture is not good.
    • Make sure as you extend the windrow, you have easy access to the finished castings after you complete the process.
    • The KISS plan minimizes exposure to heat. This is ideal for both dairy and horse manure. Be sure to monitor the compost when the weather starts warming up. Be proactive about controlling pathogens and/or weed growth with temperatures above 75°F.
    Once the first windrow is established and layered at least 2 feet thick, the next step is to increase the length of the windrow. Add new layers of manure to the sides, next to the first windrow. You’ll observe the worms in the first pile begin to migrate to the fresher feed. Every week add additional manure alongside the first windrow until you’ve formed a new second windrow. You can replicate these steps to create however many windrows you want, given the amount of space available. You’ll observe the Red Worms migrating from windrow to windrow. As they do, they’ll leave behind a rich source of high quality castings called Vermicompost.

    KISS Plan for Vermicomposting on dairy and horse farms
    To optimize ideal conditions for compost decomposition and converting compost to vermicompost (worm castings) using Red Worms, four variables should be monitored closely; temperature, moisture levels, oxygen and soil pH balance. Research conducted by experts in the industry list these variables and the ideal growth environment for Red Worms below:
    • Ideal temperature: 15 to 20°C (60 to 70°F)
    • Ambient moisture level: 64 to 80 percent
    • Oxygen requirement: gaseous oxygen from the air.
    • Soil pH: > 5 and < 9
    Earthworms consume large quantities of organic material equivalent their own body weight every 24 hours. They expend energy turning the soil, which, in effect will aerate the windrows and minimize odor buildup. Half of what Red Worms eat will become viable plant food (earthworm castings).
    As you become familiar with the KISS process, you’ll be an eyewitness to the methods Red Worms use to convert your compost to earthworm castings. Remember each windrow has a different time frame as to when the worm castings are ready for harvest can be processed.

    Always give each windrow a little longer time before harvesting to ensure the worms have thoroughly broken down the vermicompost. Doing so will also leave more worm castings in the soil.

    While your worms are hard at work for you, monitoring the amount of moisture in the air will impact their ability to work even harder. If possible, we encourage farmers to use a misting irrigation system that runs through the entire windrow.
    If you have the irrigation system set on a timer, it will enable you to be consistent with watering and controlling the amount of moisture windrows receive. Remember to always keep the soil moist, but don’t over water it to where the bottom of the windrow becomes soggy.

    If your windrows are in an exposed environment, it’s strongly recommended you use plastic tarps or a similar fabric to divert rainwater runoff and prevent leaching. Doing so will also preserve nutrients in the vermicompost, ensuring an optimal climate for worms.

    Even after the worms have left their castings, it’s wise to cover the casting and prevent any loss of nutrients from exposure to rain or the exposed environment.
    There are numerous companies you can contact which sell tarps and fabric covers specifically for composting, which can be used for vermicomposting. We recommend:

    ? Midwest Bio-Systems – 800-689-0714, ask for compost

    ? Champlain Valley Compost Co. 802-425-5556, ask for the Compostex Cover.
    ? W.L. Gore & Associates, Inc 888 914 4673, ask for the Compoguard

    Timing the harvest is critical to getting the best return on your time and investment. Worms will always create the best castings when they have an ideal environment to thrive in. Expect to harvest castings from the most active windrows in as little as two months. Depending on the size of the windrow and the environment worms grow in, it can take up to six months for castings to be ready for harvest. As you become familiar with the KISS Plan, applying it on your farm, you’ll be able to anticipate the ideal times for harvesting castings.
    Learning the science of vermicomposting can be one of the wisest investments you make with your organic compost. Following the KISS plan ensures you’re following a proven process that’s used by farmers, gardeners and industry experts from around the world.

  3. #3
    Join Date
    Oct 2008

    Vermicasting (or Vermicomposting): Processing Organic Wastes Through Earthworms

    Agdex#: 743/537
    Publication Date: 02/2010
    Order#: 10-009
    Last Reviewed: 02/2010
    Written by: Hala Chaoui - Agricultural Engineer/Urban Farms Organic

    | PDF Version - 265 KB | EPUB Version - 257 KB |

    Table of Contents

    1. Introduction
    2. Important Facts About Vermicasting
    3. Vermicast Fertilizer Characteristics
    4. Earthworms 101
    5. Bin or Reactor Design
    6. Batch Systems
    7. Continuous Flow Systems
    8. Example Bin Design for Two-Person Household
    9. Separating Earthworms From the Vermicasts
    10. Conclusion
    11. References


    Vermicasting, also called vermicomposting, is the processing of organic wastes through earthworms (Figure 1). 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.

    Figure 1. Red wigglers (Eisenia fetida) eat organic wastes, such as vegetable peelings, then excrete vermicasts. (Photo courtesy of Melissa Walters)
    Vermicast Fertilizer Characteristics

    Vermicast nutrient content varies with earthworm feed type, but feeding waste to earthworms does cause nitrogen mineralization, followed by phosphorous and sulphur mineralization after egestion. A typical nutrient analysis of casts is C:N ratio 12–15:1; 1.5%–2.5% N, 1.25%–2.25% P2O5 and 1%–2%, K2O at 75%–80% moisture content. The slow-release granules structure of earthworm casts allows nutrients to be released relatively slowly in sync with plant needs.
    Ammonium is the main contributor to salinity levels. Earthworms are repelled by salinity levels above 5 mg/g. Therefore, if the starting material is low in salt, the resulting vermicast will be as well. In fresh vermicast, ammonium mineralized in the earthworm gut is nitrified over 2 weeks.
    Pathogen levels are low in vermicast, which is considered a Type A biosolid when excreted by earthworms. This is a lower pathogen level than in typical composts. Vermicast is low in pathogens because earthworms consume fungi, and aerobic bacteria do not survive low oxygen levels in the gut. Low pathogen levels could also be due to the fact that vermicasting does not build up heat, which allows disease-suppressing organisms to survive the vermicasting process and outcompete pathogens.
    Earthworms 101

    Earthworms are epigeic (surface dwellers), endogeic (burrow up to 15 cm deep) or anecic (burrow vertical channels, about 1 m deep). Epigeic earthworms such as Eisenia fetida (red wigglers) are the best adapted to ingest organic wastes. Earthworms can double their population in 60 days.
    Red wigglers can consume 75% of their body weight per day. Earthworms weigh about 0.2 g and require oxygen and water, both exchanged through their skin.
    As organic matter passes through the earthworm gut, it is mineralized into ammonium (later nitrified) and other plant nutrients. The grinding effect of its gizzard and the effect of its gut muscle movement result in the formation of casts. Most pathogens are consumed in the earthworm gut, since earthworms feed on fungi, and pathogenic bacteria cannot survive in the low-oxygen environment inside the earthworm gut.
    Feed Preferences
    The ideal feed for earthworms is food or animal waste and fresh, green, plant waste, rich in nitrogen or precomposted (for up to 2 weeks to make it easier to digest). Ideally, earthworm feed has a 25:1 carbon-to-nitrogen (C:N) ratio and a pH between 6.5 and 8 (close to neutral) – sudden pH fluctuations repel earthworms.
    Ideal earthworm feed is:

    • porous, allowing oxygen to penetrate
    • warm (25°C): worms can survive in temperatures 0°C–35°C, but at lower temperatures they are not as active and die at freezing temperatures
    • moist, but not wet: 75% moisture is ideal, like wet soil at field capacity (earthworms migrate out of wet materials)
    • not too dense: below 640 kg/m3 (40 lb/ft3) – like the fluffy density of peat moss
    • not salty: below 0.5% salinity – higher is too toxic
    • devoid of toxins such as de-worming medicine, detergent cleansers, pesticides and tannins

    Online calculators for optimizing worm feeds are available. Search online for "vermicasting, feed mixtures with optimal characteristics." The calculation uses the percentage nitrogen, percentage carbon, water content and density of each feed material, plus the total desired feed quantity.
    Light Sensitivity
    Earthworms have eye-cells on their skin that trigger pain when exposed to any light but blue light, keeping them underground during daylight. They will try to leave any material if it does not meet their feed requirements, but if a light is shining at the surface of the material, they will stay where they are.
    Bin or Reactor Design

    The goal for any vermicasting system is to:

    • provide worms with a palatable feed
    • have worms digest waste at the highest rate possible
    • keep worms from migrating out of or to the edge of the windrows, raised beds or bins (Figure 2)

    Waste must:

    • have the required pH and salinity levels
    • be moist but drained of excess water
    • be neither too cold nor too hot
    • be stacked in thin layers that diffuse air

    Figure 2. Left: Stacked bin system simplifies separating finished vermicast from the earthworms and fresh waste. Right: Raised vermicasting beds (photos courtesy of Cathy's Crawly Composters, Toronto).

    Drainage and Aeration
    For appropriate drainage and aeration, container walls, bottom and side walls must be made of a perforated material. Many commercially available vermicasting bins have a few holes at the bottom for drainage, but this is not enough. A screen-type floor surface allows drainage, unlike common bedding materials. A screen size of 4 mm (5/32 in.) will keep most waste particles in.
    Earthworms will not fall through this size of hole but they can burrow through this size of hole to get to fresh wastes if need be.
    Some commonly used bedding types are dense and can become waterlogged, not allowing air to diffuse through the drainage/aeration holes in the bin bottom. Instead, consider using a layer of finished vermicast on the bin bottom for the start-up period because worms will burrow through it, resulting in good aeration and drainage. Starting with a vermicast layer also provides room to keep the worm stocking density lower than the maximum 300 worms/L of material. Higher densities reduce worm efficiency. Keep an air space of at least 5–10 cm depth (2–4 in.) below the screen floor for free drainage. Earthworms could burrow through the 4-mm screening on the bottom of the bin, but they choose not to because there is no food there, just open air. Leachate draining through can be collected and reintroduced to the bin.
    Waste materials should have a moisture content of 75% (field capacity), never more than 85%. Regular watering, or automatic sprinkling in the case of large scale systems, is usually needed. If waste materials with elevated levels of water content are added, such as food waste (fruits and vegetables are about 90% moisture), watering is not necessary, and drainage will correct the moisture level if it exceeds 75%.
    Thickness of the Waste Layer
    To prevent anaerobic conditions (lack of oxygen), which can result in fermentation and heat build-up, design the vermicasting bin, raised bed or windrow pile to keep the waste layer at a thickness of 30 cm (1 ft) or less. This thickness allows air to passively diffuse into the material, aided by the canals burrowed by earthworms. This keeps the pile aerated and cool, which earthworms prefer. A thin layer of waste helps prevent compaction of the bottom of the waste pile, which might cause poor aeration, fermentation and heat, all of which repel earthworms.
    Active aeration, mixing and temperature control of such a thin layer of waste occurs through the burrowing action of the earthworms. The earthworms do the work, unlike an active composting system where aeration, mixing and temperature control are accomplished by fans and/or machinery.
    Since earthworms require a temperature range of 0°C–35°C (optimum is 25°C), year-round vermicasting systems must be designed carefully for the Ontario climate. The process is odourless but does not generate heat on its own, so one option is to place the bin indoors. If this is not possible, insulate bins and place them partly underground in a sheltered location to help temper outside temperature fluctuations.
    Odours and Flies
    Odorous gases (volatile organic compounds) and heat are produced during fermentation, which can occur in poorly aerated (anaerobic) organic materials. This is often a problem in compost piles if they are not aerated or mixed. However, earthworms thrive in aerobic conditions, where fermentation and the resulting heat and odours do not occur. If designed properly, vermicasters do not produce odours.
    When a vermicaster does produce odours and flies, it is likely due to excess water. Proper drainage using raised screen surfaces (4 mm) at the bottom of the container and/or reducing the thickness of the waste to no more than 30 cm should resolve this situation.
    Batch Systems

    The system can be designed as batch or continuous flow. In a batch system, the waste is inoculated with earthworms, which then process the entire quantity of waste into vermicast. The casts are collected and separated from the earthworms, ending the process.
    In a continuous-flow vermicaster, fresh waste is added at one end of the process, while finished vermicast is collected from the other. This can happen at opposite ends or opposite heights of a windrow, bin or raised bed (Figure 2). Current industrial vermicasting machinery features mechanized beds where two adjacent moving surfaces cause finished vermicast at the bottom of the bed to fall through its perforated surface, as fresh waste is added at the top. On a domestic scale, the same vertical continuous flow system is used in suspended bags (Figure 3) whereby the user can collect finished vermicast from a closable opening at the bottom of the bag. Fresh waste is added from an opening at the top.

    Figure 3. Schematic of a continuous-flow suspended bag vermicaster, adapted from a commercially available vermicaster by Finished vermicast is harvested from a closable opening at the bottom of the bag, while fresh waste is added through an opening at top.
    Continuous Flow Systems

    A vermicast system is dynamic. What happens in a typical two-bin system, over time, determines its optimum dimensions, the required starting amount of earthworms, the amount of starting medium required for the earthworms to burrow in and the bin cycle time.
    Figure 4 was created using simulation software and shows how much waste is consumed over time, how much volume the waste and earthworm casts take up and how crowded the worms are over time.

    • At Day 0, all earthworms are in Bin 1 (blue) where waste is added daily and entirely consumed by Day 16. This is where the unconsumed waste area tapers off in the graph.
    • At Day 16, Bin 2 (brown) is placed on top of Bin 1. Bin 2 is partially filled with fresh waste and starting medium, side-by-side, on its 4-mm screened floor in order to attract earthworms from Bin 1 below to burrow up into Bin 2. See Figures 2 (left), 4 and 5.
    • All earthworms move into Bin 2 over 1 week, as shown by overlapping earthworm density curves between Days 16 and 23.
    • After Day 16, all fresh waste is added daily to Bin 2 and consumed by Day 32.
    • The two "dips" in the brown area of unconsumed waste are due to not having waste put into the bin for 2 days out of the cycle, which commonly happens, for example, when people are away from home for a day or two.
    • The peak volume values occur on Days 15 and 30 at 68 L (68,000 cm3), which is the minimum bin volume required for one cycle.
    • 1.5 kg of earthworms will consume 30 days' worth of household waste from a two-person household (3 L/day) over a one-month period.
    • 1.5 kg of earthworms is 7,500 worms at 0.2 g each.
    • To prevent worms from being densely packed, divide the number of worms (7,500) by a maximum stocking density of 250 worms/L = 30 L of starting medium required. Finished worm cast works well as a medium and will be needed in each bin. 250 worms/L is high, but drops over time as fresh wastes are added daily.
    • Figure 4 shows that 15 days' worth of waste would be added to the original starting medium of 30 L of casts.
    • Since the depth of materials should never exceed 30 cm, while the minimum bin volume must be 68 L (68,000 cm3), a square bin width and length of 50 cm x 50 cm will give more than enough room (30 cm x 50 cm x 50 cm = 75,000 cm3, or 75 L)

    The result is a one-month cycle and an easy separation of earthworms from the waste. As shown inFigure 4, the cycle includes points in time where a second bin is added on top of the first and where earthworms finish migrating out of the first bin into the second, allowing finished vermicast to be collected. Online calculators are available to determine time and bin volume requirement for any daily rate of waste. Search online for "vermicasting, optimal bin size."
    A throughput system (Figure 3) would be similar to two superimposed bins, except that earthworms would continuously transition from finished vermicast at the bottom to fresh waste at the top. Based on the graph in Figure 4, 5 L of vermicast could be removed from a throughput system only five days into the process, then about 1 L per day after, assuming an ideal earthworm stocking density. This creates space for more fresh waste.

    Figure 4. Vermicasting bin for a two-person household.
    Example Bin Design for Two-Person Household

    Figure 5 shows a solid container housing two smaller containers built of 4-mm mesh screen, which are propped up to allow air to circulate underneath while keeping waste particles and earthworms inside. Once earthworms transform the contents of the first container, a second one containing 6–10 L of fresh, moist organic material is placed on top of it. Earthworms are allowed to migrate up into the fresh waste before the lower bin of finished vermicast is removed, and the top bin takes its place. Containers can also be placed side by side, with wastes placed horizontally between the tops of the containers to entice worms to move to a new bin.
    Separating Earthworms From the Vermicasts

    Earthworms can be separated from their vermicasts by:

    • placing fresh feed at the opposite end of the continuous flow system, attracting them away from the finished vermicast
    • mechanical sieving by a drum screen or a moving grate at the bottom of a bin or raised bed (Figure 2)
    • mild heating
    • drying the vermicast materials with a fan in a batch process, diverting worms to moister material
    • repelling them by using low-level electric current (this method is in the research stage and requires careful design because of safety concerns)

    Figure 5. Volume of wastes (consumed and unconsumed) in litres (left side of graph) and earthworm density in earthworms per 0.1 L (right side of graph) over a 1-month period in a two-bin household vermicasting system. (Note: 25 earthworms/0.1 L = 250 earthworms/L)

    A properly designed vermicasting system will process organic waste into vermicast in 22–30 days. This process self-aerates and does not require mechanical aeration or mixing. Earthworm beddings commonly used in earthworm bins can be replaced with a screen or mesh raised bottom surface and enough finished vermicast to prevent excessive earthworm stocking density and provide proper drainage. Adequate drainage and aeration prevent odours, flies or the migration of earthworms out of the waste. Vermicasting can be done on a domestic, farm or industrial scale in waste-processing facilities and could be sited near residential areas, minimizing waste and fertilizer transportation costs. When added to plants, vermicast has been shown to improve resistance to disease, yield and protein content of plants relative to other commercial fertilizers.

    Chaoui, I.H., Zibilske, L.M., Ohno, S. 2003. Effect of earthworm casts and compost on microbial activity and plant nutrient uptake. Soil Biology and Biochemistry, 35, 295–302.
    Chaoui, H., and Keener, H.M. 2008. Modeling the effectiveness of an electric field at repelling earthworms. Biosystems Engineering, 100 (3), 409–421.
    Edwards, C.A., and Bates, J.E. 1992. The use of earthworms in environmental management. Soil Biology and Biochemistry, 14 (12): 1683–1689.
    Frederickson, J., and Howell, G. 2004. Large-scale vermicomposting: Emission of nitrous oxide and effects, (5/6), 724–730
    Haynes, R.J., Fraser, P.M., Tregurtha, R.J., Piercy, J.E. 1999. Size and activity of the microbial biomass and N, S and P availability in EW casts derived from arable and pastoral soil and arable soil amended with pant residues. Pedobiologia, 43 (6), 568–573.
    Mitchell, A. 1997. Production of Eisenia fetida and vermicompost from feed-lot cattle manure. Soil Biology and Biochemistry, 29 (3–4), 763–766.
    Ndegwa, P.M., Thompson, S.A., Das, K.C. 1999. Effects of stocking density and feeding rate on vermicomposting of biosolids. Biores. Technol. 71 (1), 5–1.
    Santamaria-Romero, S., Ferrera-Cerrato, R., Almaraz-Suarez, J.J., Galvis-Spinola, A., Barois-Boullard, I. 2001. Dynamics and relationships among microorganisms, C-organic and N-total during composting and vermicomposting. Agrociencia-Montecillo, 35 (4), 377–384.
    Shipitalo, M.J., & Protz, R. 1989. Chemistry and micromorphology of aggregation in earthworm casts. Geoderma, 45, 357–374.
    Schonholzer, F., Hahn, D., and Zeyer, J. 1999. Origins and fate of fungi and bacteria in the gut ofLumbricus terrestris L. studied by image analysis. FEMS Microbiology Ecology, 28 (3), 235–248.

    For more information:
    Toll Free: 1-877-424-1300

  4. #4
    Join Date
    Oct 2008

  5. #5
    Join Date
    Oct 2008
    Rapid composting methods: Vermicomposting

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    The potential of composting to turn on-farm waste materials into a farm resource makes it an attractive proposition. Composting offers several benefits such as enhanced soil fertility and soil health, thereby increased agricultural productivity, improved soil biodiversity, reduced ecological risks and a better environment. While traditional composting procedures take as long as 4-8 months to produce finished compost, rapid composting methods offer possibilities for reducing the processing period up to three weeks.


    soil fertility


    Crop production
    Natural Resources Management




    Use of Worms: Vermicomposting
    The term "vermicomposting" had recently been coined to mean the use of earthworms for composting organic residues. Earthworms can consume practically all kinds of organic matter and they can eat their own body weight per day; thus, for example, one kilogram of worms can consume one kilogram of residues every day. The excreta or castings of the worms are rich in nitrate, available forms of phosphorus, potassium, calcium and magnesium.
    The passage of soil through earthworms promotes bacterial and actinomycetes growth; actinomycetes thrive well in the presence of worms and their content in worm casts is over six times more than in the original soil.

    Kind of worms

    A moist compost heap of 2.4 m by 1.2 m and 0.6 m high can support a population of more than 50 000 worms. The introduction of worms into a compost heap has been found to mix the materials, aerate the heap and hasten decomposition. Turning the heaps is not necessary if earthworms are present to do the mixing and aeration. The ideal environment for the worms is a shallow pit and the right sort of worms are necessary. Lumbricus rubellus (the red worm) and Eisenia foetida are thermo-tolerant and so particularly useful. Field worms Allolobophora caliginosa and night crawlers (Lumbricus terrestris) will attack organic matter from below but the latter do not thrive during active composting, being killed more easily than the others at high temperature. European Night Crawlers (Dendrabaena venetaor Eisenia hortensis) are commercially produced as well and have been successfully used in most climates. This night crawler grows to about 4 inches and up to about 8 inches. The African Night crawler (Eudrilus eugeniae), is a large, tropical worm species. It does tolerate heats a bit higher than does E. foetida, provided there is ample humidity, but has a narrow temperature tolerance range. However, it cannot survive at temperatures below 45 degrees F.

    Vermicomposting in Philippines

    The worms used are Lumbricus rubellus and/or Perionyx excavator. The worms are reared and multiplied from a commercially-obtained breeder stock in shallow wooden boxes stored in a shed. The boxes are approximately 45 cm x 60 cm x 20 cm and have drainage holes; they are stored on shelves in rows and tiers. A bedding material is compounded from miscellaneous organic residues such as sawdust, cereal straw, rice husks, bagasse, cardboard and so on, and is moistened well with water. The wet mixture is stored for about one month, being covered with a damp sack to minimize evaporation, and is thoroughly mixed several times. When fermentation is complete, chicken manure and green matter such as ipil ipil leaves or water hyacinth is added.
    The material is placed in the boxes and should be sufficiently loose for the worms to burrow and should be able to retain moisture. The proportions of the different materials will vary according to the nature of the material but a final protein content of about 15% should be aimed at. A pH value as near neutral as possible is necessary and the boxes should be kept at temperatures between 20oC and 27oC. At higher temperatures, the worms will aestivate and, at lower temperatures, they hibernate. In spite of their being able to eat the bedding material, the worms at this stage are fed regularly; for every kilogram of worms a kilogram of feed is given every 24 hours. For each 0.1 m2 of surface area, 100 g of breeder worms are added to the boxes. The feedstuffs used are again various and include chicken manure, ipil ipil, vegetable wastes and so on. At one farm, water hyacinth is grown specifically and used fresh (chopped up) as the sole source of feed. Some form of protection against predators is necessary; predators can include birds, ants, leeches, rats, frogs and centipedes.

    Composting procedure

    A series of pits (the number depending on available space) are dug approximately 3 m x 4 m x 1 m deep, with sloping sides. Bamboo poles are laid in a parallel row on the pit floor and covered with a lattice of wood strips. This provides the necessary drainage as the worms cannot survive in a waterlogged environment. The pit is then lined with a suitable material to keep the worms from escaping into the surrounding soil (although, with the abundant feed provided in the compost heap, this may not happen) and yet permit drainage of excess water. At the farm under consideration, old animal feedstuff sacks were used. The pit can now be filled with rural organic residues such as straw and other crop residues, animal manure, green weeds, leaves and so on. The filled pit is covered loosely with soil and kept moist for a week or so. During this period, another pit can be filled as necessary.
    One or two spots on the heap are then well watered and worms from the breeding boxes are place on top; the worms immediately burrow down into the damp soil. To harvest the worms from the boxes, two-thirds of the box is emptied into a new box lined with banana leaf or old newspaper. The original box can now be provided with fresh bedding material and those worms remaining will again multiply. The worms emptied from the box are picked out by hand for adding to the heap. The compost pit is left for a period of two months; ideally it should be shaded from hot sunshine and it must be kept moist. Within two months, about 10 kg of castings will have been produced per kilogramme of worms. The pit is then excavated to anextent of about two-thirds to three-quarters and the bulk of the worms removed by hand or by sieving. This leaves sufficient worms in the pit for further composting and the pit can be refilled with fresh organic residues. The compost can be sun-dried and sieved to give a very good quality material. A typical analysis is: Organic matter 9.3%, Nitrogen 8.3%, Phosphorus 4.5%, Potassium 1.0% (water-soluble), Calcium 0.4%, Magnesium 0.1%. The excess worms that have been harvested from the pit can be used in other pits, sold to other farmers for the same purpose, used or sold for use as animal feed supplement, used or sold for use as fish food or, if there is no social taboo, used in certain human food preparations.

    Vermicomposting in Cuba

    In Cuba, different methods are used for worm propagation and vermicomposting.

    Worm troughs in a row:
    The first and most common is cement troughs, two feet wide and six feet long, much like livestock watering troughs, used to raise worms and create worm compost. Because of the climate, they are watered by hand every day. In these beds, the only feedstock for the worms is manure, which is aged for about one week before being added to the trough. First, a layer of three to four inches of manure is placed in the empty trough, then worms are added. As the worms consume the manure, more manure is layered on top, roughly every ten days, until the worm compost reaches within a couple inches of the top of the trough, about two months. Then the worms are separated from the compost and transferred to another trough.

    The second method of vermicomposting is windrows. Cow manure is piled about three feet across and three feet wide. Then it is seeded with worms. As the worms work their way through it, fresh manure is added to the end of the row, and the worms move forward. The rows are covered with fronds or palm leaves to keep them shaded and cool. Some of these rows have a drip system - a hose running alongside the row with holes in it. But mostly, the rows are watered by hand. Some of these rows are hundreds of feet long. The compost is gathered from the opposite end when the worms have moved forward. Then it is bagged and sold. Fresh manure, seeded with worms, begins the row and the process again. Some of the windrows have bricks running along their sides, but most are simply piles of manure without sides or protection. Manure is static composted for 30 days, then transferred to rows for worms to be added. After 90 days, the piles reach three feet high. Worm populations, they say, can double in 60 to 90 days. Windrows are also used to compost rice hulls and sugar cake (cake is what is left after sugar cane is processed), but this too is mixed with animal manure. Sometimes food scraps added to worm beds.

    Vermiculture in India

    Preparing vermicompost:

    Materials - breeder worms, a wooden bed and organic wastes.

    The bed should be 2 1/2 ft. high x 4 ft. wide x any length desired. Apply worms for every part of waste.

    Sieving and shredding- Decomposition can be accelerated by shredding raw materials into small pieces.

    Blending- Carbonaceous substances like sawdust, paper and straw can be mixed with nitrogen rich materials such as sewage sludge, biogas slurry and fish scraps to obtain a near optimum C/N ratio of 30:1 / 40:1. A varied mixture of substances produces good quality compost, rich in major and micro nutrients.
    Half digestion- The raw materials should be kept in piles and the temperature allowed to reach 50-55oC. The piles should remain at this temperature for 7 to 10 days.

    Moisture, temperature and pH- The optimum moisture level for maintaining aerobic conditions is 40-45%. Proper moisture and aeration can be maintained by mixing fibrous with nitrogen rich materials. The temperature of the piles should be within 28-30oC. Higher or lower temperatures will reduce the activity of micro flora and earthworms. The height of the bed can help control the rise in temperature. The pH of the raw material should not exceed 6.5 to 7.

    After about a month the compost is ready. It will be black, granular, lightweight and humusrich. To facilitate separating the worms from the compost, stop watering two to three days before emptying the beds. This will force about 80% of the worms to the bottom of the bed. The rest of the worms can be removed by hand. The vermicompost is then ready for application.


    Food and Agriculture Organization of the United Nations (FAO)

    Food and Agriculture Organization of the United Nations (FAO)
    FAO's mandate
    Achieving food security for all is at the heart of FAO's efforts - to make sure people have regular access to enough high-quality food to lead active, healthy lives.
    FAO's mandate is to raise levels of nutrition, improve agricultural productivity, better the lives of rural populations and contribute to the growth of the world economy.
    Organización de las Naciones Unidas para la Agricultura y la Alimentación (FAO)
    El mandato de la FAO
    Alcanzar la seguridad alimentaria para todos, y asegurar que las personas tengan acceso regular a alimentos de buena calidad que les permitan llevar una vida activa y saludable, es la esencia de las actividades de la FAO.El mandato de la FAO consiste en mejorar la nutrición, aumentar la productividad agrícola, elevar el nivel de vida de la población rural y contribuir al crecimiento de la economía mundial.
    Organization des Nations Unies pour l'alimentation et l'agriculture
    Le mandat de la FAO
    Atteindre la sécurité alimentaire pour tous est au coeur des efforts de la FAO - veiller à ce que les êtres humains aient un accès régulier à une nourriture de bonne qualité qui leur permette de mener une vie saine et active.
    Le mandat de la FAO consiste à améliorer les niveaux de nutrition, la productivité agricole et la qualité de vie des populations rurales et contribuer à l’essor de l’économie mondiale.



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    Industrial vermicomposting to eliminate E. coli, Salmonella in human sewage.


    January 17, 2013 · by admin · in Waste Management
    Bruce Eastman inspects biosolids at VermiCo seminar

    Can earthworms completely eliminate disease-causing organisms from human waste? A pilot project in Florida established conclusively that, after introducing earthworms into biosolids infected with E. coli, Salmonella, and other harmful organisms, the worms eliminated these pathogens, rendering the resulting material (vermicompost) safe for handling and application to plants.

    Compost Science & Utilization (Winter 2001,Volume 9, Number 1) contains the landmark publication “The Effectiveness of Vermiculture in Human Pathogen Reduction for USEPA Biosolids Stabilization.” The publication of this study in a peer-reviewed scientific journal confirms the efficacy of earthworms in eliminating human pathogens in biosolids (wastewater residuals) to achieve Class A stabilization, the highest rating of the USEPA, an indication that the material has been rendered safe because it is virtually free of harmful organisms.

    The Florida-based study was conducted in two phases, the first beginning in March 1996 at the city of Ocoee’s Wastewater Treatment Facility in Ocoee, Florida. The purpose of the study was to see if vermiculture offered a low-cost but effective means of stabilizing biosolids. Dr. Jim Smith, Senior Environmental Engineer and Pathogen Equivalency Commission (PEC) Chair for the USEPA indicated by personal communication to principal investigator Bruce R. Eastman of the Orange County Environmental Protection Division (OCEPD) that a three– to four-fold reduction in indicator organisms would be sufficient to warrant serious consideration of vermicomposting as an effective stabilization methodology. In fact, the tests indicated that all of the pathogen indicators were reduced to safe levels in as short a time as 144 hours. Significant reduction of all pathogens had been achieved through vermicomposting within the first three days (72 hours).

    Why should anyone care that earthworms reduce pathogens in biosolids? There may be several reasons. First, according to the authors of this paper, “The obvious inherent environmental and health hazards of unstabilized human waste can be seen in the third world nations. Rampant diseases that have debilitating consequences are common for people living in these countries. Unstabilized or improperly stabilized biosolids are a real concern and the regulations regarding stabilization reflect this ongoing concern.” Vermicomposting biosolids may offer an immediate and effective, low-cost solution to third world nations concerned with handling these wastes.

    Second, the considerable expense involved for many smaller-sized US communities to build wastewater treatment plants suggests vermicomposting may appear to be a viable and more affordable alternative. The cost-per-ton for handling these wastes is extremely high and vermicomposting may offer a lower-cost, but equally effective means of processing biosolids where volumes of material are manageable by a small work force where space is available to spread the material. Vermicomposting biosolids in major metropolitan areas may not be as practical, but the practice may be of significant benefit to many rural communities. Consider that in Florida alone there were 3,500 to 4,000 wastewater treatment facilities in 1997, but only nineteen were Class AAType I and four Class A Type I. According to Eastman, “the vast majority of these [remaining] facilities generated a product below EPA Class A standards.” The authors of this study stated “The vermicomposting method is an inexpensive low-technological procedure for achieving results comparable to other more intensive and expensiveUSEPA biosolids stabilization methods.”

    A third, and possibly the most important reason why this study has such importance is the fact that it has now been scientifically demonstrated that vermicomposting eliminates the need for thermophilic (heat) composting. USEPA regulations to stabilize biosolids are found in the Code of Federal Regulations, often termed the “Part 503 regulations.” There it states that biosolids material must be maintained in an in-vessel container at 55 degrees Celsius (131 degrees Fahrenheit) or higher for a minimum of three days. This time and temperature requirement is necessary for achieving destruction of human pathogens. (When non-containment systems are used the material must be turned five times over a period of 15 days, maintaining the same temperature requirement.) This study in vermicomposting now presents evidence for the fact that earthworms feed on pathogenic organisms and effectively clean up the potentially harmful material, rendering it safe for handling. The authors speak of “the elimination of pre-composting,” a process many believe is necessary to sanitize material even before vermicomposting. “Until recently,” the authors stated, “this step was thought to be necessary to eliminate pathogens before adding earthworms. However, this project confirms that the earthworms greatly reduce the pathogens from the biosolids during vermicomposting making the pre-composting unnecessary. The use of earthworms to vermicompost biosolids exceeded even the initial experimental expectations for pathogen reductions.”

    Four indicator organisms were introduced (spiked) into biosolids material to ensure high levels before testing began: fecal coliforms, Salmonella spp., enteric virus and helminth ova. The material was laid out in two windrows, one designated as a test row containing earthworms and the other row designated the control row. After 144 hours the test row samples showed a 6.4-log reduction in fecal coliforms compared with the control row, which only had a 1.6-log reduction. The test row samples showed an 8.6-log reduction in Salmonella spp., while the control row had a 4.9-log reduction. The test row samples showed a 4.6-log reduction in enteric viruses while the control only had a 1.8-log reduction. The test row samples had a 1.9-log reduction in helminth ova while the control row only had a 0.6-log reduction. The full-scale project was scheduled to last for 90 days, but was terminated after 68 days because the earthworms consumed material at a rate up to 1.5 times their body weight each day.

    Final analysis of the samples taken from the test row of vermicomposted biosolids indicated negative readings for E. coli, Salmonella spp., enteric virus and helminth ova. The authors concluded, “Based on experimental analyses from both the pilot and the full-scale operation, vermiculture can be used effectively as an USEPA process to treat pathogens and potentially produce Class A biosolids.”

    What remains to be done? In order to approve vermicomposting as an acceptablePFRP (Process to Further Reduce Pathogens) USEPA will want to evaluate the results of standard operating procedures (SOPs) to be suggested in a future project. Investigators will need to determine such factors as how long (duration) biosolids material must be processed by earthworms and what biomass of earthworms must be present in a given quantity of biosolids (ratio of earthworms to unprocessed material) in order to achieve Class A stabilization.

    Bibliographic citation for this article is as follows: Eastman, B.R., P.N. Kane, C.A. Edwards, L. Trytek, B. Gunadi, A.L. Stermer and J.R. Mobley. 2001. The effectiveness of vermiculture in human pathogen reduction for USEPA biosolids stabilization. Compost Science and Utilization, 9(1):38–49.

    To obtain a copy of this journal contact: Compost Science & Utilization, 419 State Avenue, Emmaus, PA 18049, USA. Telephone (610) 967‑4135; Subscribe online at One year (4 issues, US) is $129.
    For Further Reading:

    See Casting Call, February 2000, Volume 4 Issue 5 for two articles on vermicomposting and biosolids: “Vermicomposting Biosolids: Earthworms Reduce Pathogens in Sewage Sludge,” and “Will Vermistabilization of Biosolids Make a Comeback? A Brief Review ofUS Efforts.” Also, see the interview with Bruce R. Eastman, Assistant Manager for the Orange County Florida Environmental Protection Division, in the book In Their Own Words: Interviews with Vermiculture Experts, ed. Peter Bogdanov, (Petros Publishing, Merlin Oregon), 2001, pp.161–184. Also available an an ebook from

    Related Posts:

    1. Journal Publishes Study of Worms Reducing Human Pathogens in Biosolids

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    February 27, 2013 · by admin · in Key Players, Waste Management

    by Clive A. Edwards

    Thermophilic composting is becoming increasingly used for processing of a wide range of organic wastes. However, the process does not always produce high quality products that have potential for soil and land improvement. Over the last 20 years interest has increased progressively into the potential of a related process which involves the use of earthworms to break down organic wastes. In 1881, Charles Darwin first drew attention to the great importance of earthworms in the breakdown of dead plant organic material and the release of essential nutrients from it in his book “The Formation of Vegetable Mould Through the action of Worms” and his conclusions have been fully confirmed and utilized during the last century. However, only in recent years has the potential of earthworms for systems of breaking down organic wastes been explored in more depth. The basic research, which began at the State University of New York, Syracuse in the 1970s, under the leadership of Dr. Roy Hartenstein, mainly at the use of earthworms for processing sewage solids. This was expanded in the early 1980s to field-scale practical methods for disposing of poultry, pig and cattle wastes in an interdisciplinary research program under the leadership of the author, at the Rothamsted Experimental Station, U.K., involved nearly 50 scientists, including biologists, agricultural engineers, economists, and representatives of a range of commercial enterprises. These studies, which have since been complemented by research by other workers in France, Germany, Italy, Spain, and Australia, have demonstrated the very considerable economic potential of using earthworms to convert a wide range of organic wastes into valuable and efficient plant growth media.

    Earthworms fragment organic wastes extremely rapidly and increase microbial activity in them dramatically. The main difference between composting and vermicomposting is that whereas composting is a thermophilic process reaching temperatures of 60–70ºC, vermicomposting systems must be maintained at temperatures below 35ºC. Exposure of the earthworms to temperatures above this, even for short periods, will kill them, and to avoid such overheating careful management of the wastes is required. Earthworms are active and will consume organic wastes in a relatively narrow aerobic layer of 6–9 inches, that is close to the surface of a bed or container. The key to successful vermicomposting lies in adding organic wastes to the surface in successive thin layers at frequent intervals, so that any thermophilic heating that occurs does not become excessive, although if well managed, some heating will maintain the activity of the earthworms at a high level of efficiency, since vermicomposting works best at temperatures between 20ºC and 25ºC.

    Almost any agricultural, urban or industrial organic wastes can be used for vermicomposting, but some may need some form of preprocessing to make them acceptable to earthworms. Such preliminary treatments can involve washing, precomposting, macerating or mixing. Wastes from the brewing, soft drink, processed potato and paper industries, sewage solids and yard, garden and food wastes as well as sewage biosolids are particularly suitable for vermicomposting. Often, mixtures of several different wastes can be processed more readily than individual wastes, are easier to maintain aerobically, and result in a better product.

    There is an extensive but small-scale cottage industry that grows earthworms for fish bait in a variety of organic wastes. These use, almost exclusively, outdoor ground beds or windrows. Such systems require large areas of land for large-scale production and are relatively labor-intensive, even when machinery is used for adding wastes to the beds. More importantly, windrow systems process wastes relatively slowly, taking anywhere from 6 to 18 months for processing of a layer 18” deep to be complete. Since this is usually an outdoor process, there is good evidence that a large proportion of the essential plant nutrients, that are in a relatively soluble form, are either washed out or can volatilize during this long processing period. Such nutrient losses are undesirable, since they can contribute to groundwater pollution, and result in a poor, low nutrient product with relatively low potential as a plant growth medium.

    The Scientific Basis for Vermicomposting

    A few species of earthworms can consume organic wastes very rapidly and fragment them into much finer particles, by passing them through a grinding gizzard, an organ that all earthworms possess. The earthworms obtain their nourishment from microorganisms that grow upon the organic wastes; at the same time they promote further microbial activity in the wastes, so that the casts, or vermicompost, that they produce, is much more fragmented and microbially active than the organic wastes the earthworms consume. During this process, the important plant nutrients that the wastes contain, particularly nitrogen, phosphorus, potassium and calcium, are released and converted into forms that are much more soluble and readily available to plants than those in the original waste. The retention time of the waste in the earthworm is short and very large quantities are passed through an average population of earthworms. In the traditional aerobic composting process, organic wastes have to be turned regularly, or aerated in some way, in order to maintain aerobic conditions in the waste. This may often involve extensive engineering and machinery to process the wastes as rapidly as possible on a large scale. In vermicomposting, the earthworms, which survive only under aerobic conditions, take over both the roles of turning over the waste and maintaining it in an aerobic condition, thereby lessening the need for expensive engineering.

    The major constraint to vermicomposting is that, in contrast to traditional composting, which is a thermophilic process that can raise temperatures in the waste to more than 70ºC, vermicomposting systems must be maintained at temperatures below 35ºC. The processing of organic wastes by earthworms occurs most rapidly at temperatures between 15ºC and 25ºC (60º to 79ºF) and at moisture contents of 70% to 90%. Outside these limits, earthworm activity and productivity and the rate of waste processing can fall off, and for maximum efficiency, the wastes should be maintained as close to these environmental limits as possible. The earthworms are also sensitive to certain conditions in the wastes. In particular, earthworms are very sensitive to ammonia and salts and certain other chemicals. For instance, they will die quite quickly if exposed to wastes containing more than 0.5 mg of ammonia per gram of waste and more than 0.5% salts. However, salts and ammonia can be washed out of organic wastes readily or dispersed by precomposting. Contrary to common belief, earthworms do not have many serious natural enemies, diseases or predators and can survive exposure to many adverse conditions.

    Types of Vermicomposting Technology Available

    A number of species or earthworms that are specific to organic wastes have been used in vermicomposting. The temperate species most commonly used world-wide is Eisenia fetida (the tiger or brandling worm). Another suitable temperate species is Lumbricus rubellus (the red worm), and two tropical species, Eudrilus eugeniae (the African night-crawler), and Perionyx excavatus, an Asian species; the latter two species are very productive, but cannot withstand temperatures below 5ºC. Each species has its particular favorable environmental requirements and it is important to choose the best species for any climate and waste.

    The traditional methods of vermiculture have been based on beds or windrows on the ground containing waste up to 18″ deep, but these have numerous drawbacks, particularly in terms of land and labor requirements. They also have the major drawback that when the vermicompost is collected it is necessary to use rotating mesh trommels or other mechanical means to remove the earthworms from the processed materials.

    It is possible to use batch vermicomposting systems involving bins or larger containers, often stacked one above the other in racks. Such container systems, particularly if large, have the drawback of needing considerable handling and lifting machinery, and there are also problems in adding water to maintain the moisture contents and in adding additional layers of waste at frequent intervals. Hence, large-scale batch systems have not been used much on a commercial basis.
    However, small-scale container systems have been used extensively to process domestic and institutional food wastes. They range from simple raised containers, described by Mary Appelhof in her book “Worms Eat My Garbage” (1997), to more sophisticated stacking systems marketed under names such as “Can O’Worms”, the “Worm Factory,” “Wriggly Ranch” and the “Worm Gin.” Such systems have been very popular in schools, which involve the children in their operation and with certain municipal waste authorities, such as in Vancouver, Canada, and various cities in Australia which subsidize their purchase and use.

    In recent years, much more efficient systems of vermicomposting have been developed. These are based on large containers raised on legs above the ground, that allow wastes to be added at the top from mobile gantries and collected mechanically through mesh floors at the bottom using breaker bars. Such methods were developed and tested extensively by engineers at the National Institute for Agricultural Engineering, Silsoe, in England. The methods they designed ranged from relatively low technology systems using manual loading and waste collection systems, to large (128 ft long x 8 ft wide x 3 ft deep), completely automated and hydraulically-driven continuous flow reactors, that have operated successfully for several years, using the original earthworm population, which reaches an equilibrium population of about 2 lbs or 500‑1000 earthworms per square foot, and involving short retention times within the reactor. For instance, such reactors can fully process three-feet deep layers of suitable organic wastes in 30–45 days. Although these systems require more capital outlay, the cost of the reactor can usually be recouped in 1–3 years, and they can be operated on a large scale with minimal labor requirements. An automated reactor that will process 1000 tons of waste per year can be built for $15,000–30,000 and the manually-operated, lower technology systems that work on a similar principle cost much less. Economic studies have shown such reactors to have much greater economic potential to produce high grade plant growth media very quickly and efficiently than windrows or ground beds. A large-scale system in southern France, developed by Dr. Marcel Bouché and based on similar principles, is part of a total recycling waste system for a small town, involving separation and sorting of the wastes followed by composting, vermicomposting, and sieving. This system converts 27% of the total waste stream for the town into a valuable vermicompost.

    Marketing of Products

    There are many commercial attractions to finding methods of converting urban and industrial organic wastes into materials that do not have to go into landfills. Such economics become even more attractive if the process produces a value-added horticultural plant growth medium with considerable commercial value.

    Extensive plant growth trials at the Ohio State University have shown that substitution of 10% to 20% of the best horticultural plant growth media by vermicomposts, increased the rates of germination, growth, flowering, and fruiting of a wide range of ornamental and vegetable crops very considerably. This places considerable commercial value on vermicomposts, although the market is only recently being fully exploited. Even without a proper marketing structure, vermicomposts can be sold readily for $30–40 per cubic yard but they also have been readily marketed for high-grade horticultural use for as much as $150 per cubic yard, after appropriate standardization, formulation, and packaging. Such standardization often involves some acidification (or mixing with peat). As much as $300 per ton has been offered for good quality export vermicomposts, and with good marketing, even higher returns have been realized. The more standard and well-formulated the product, the greater is its market potential.

    Additional Information Sources

    Appelhof, M. 1997. Worms Eat My Garbage. Flower Press, Michigan, 162 pp.
    Edwards, C.A. and Neuhauser, E.F. (Eds.) 1988. Earthworms in Waste and Environmental Management. SPB Academic Publ. The Hague, Netherlands, 392 pp.
    Edwards, C.A. and Bohlen, P.J. 1996. The Biology and Ecology of Earthworms. 3rd Ed. Chapman and Hall, London, 426 pp.
    Edwards, C.A. (Ed.) 1998. Earthworm Ecology. CRC Press/St. Lucie Press, Boca Raton, 389 pp.
    Edwards, C.A. 1995. Historical Overview of Vermicomposting. BioCycle, June 1995, 56–58.
    Subler, S., Edwards, C.A. and Metzger, J. 1998. Comparing Vermicomposts and Composts. BioCycle, July 1998, 63–65.

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