Manual on Vermiculture and Vermicomposting

Manual of On-Farm Vermicomposting and Vermiculture By Glenn Munroe Organic Agriculture Centre of Canada





Acknowledgements EcoAction Program of Environment Canada and New Ground Vermicomposting, Halifax, Nova Scotia Jennifer Scott, Centre Burlington, Nova Scotia Kipawo Holsteins, Grand Pre, Nova Scotia Holdanca Farms Ltd., Wallace, Nova Scotia


Table of Contents 1 Introduction: Vermiculture and Vermicomposting..................................................1 1.1 The Difference between Vermiculture and Vermicomposting ..........................1 1.2 The Compost Worm ....................................................................................1 1.3 Why Bother? An Overview of Potential Benefits and Constraints.....................2 1.4 What this Manual Can Do for You.................................................................3
2 Working with Worms: The Basics .........................................................................5 2.1 What Worms Need ......................................................................................5 2.1.1 The Five Essentials ..................................................................................5 2.1.2 Bedding ..................................................................................................5 2.1.3 Worm Food .............................................................................................7 2.1.4 Moisture ...............................................................................................10 2.1.5 Aeration................................................................................................10 2.1.6 Temperature Control .............................................................................10 2.2 Other Important Parameters ......................................................................11 2.3 Calculating Rates of Reproduction ..............................................................12 2.4 Projecting Vermicompost Outputs ..............................................................14 2.5 Pests and Diseases....................................................................................15
3 An Overview of Vermicomposting Systems..........................................................17 3.1 Basic Types of Systems .............................................................................17 3.2 Windrows .................................................................................................17 3.2.1 Static pile windrows (batch) ...................................................................17 3.2.2 Top-fed windrows (continuous flow) .......................................................20 3.2.3 Wedges (continuous flow)......................................................................21 3.3 Beds or Bins .............................................................................................22 3.3.1 Top-fed beds (continuous flow) ..............................................................22 3.3.2 Stacked bins (batch or continuous flow)..................................................23 3.4 Flow-Through Reactors..............................................................................24
4 On-Farm Vermiculture .......................................................................................26 4.1 Vermiculture Systems ................................................................................26 4.2 Methods of Harvesting Worms ...................................................................26 4.2.1 General.................................................................................................26 4.2.2 Manual Methods ....................................................................................26 4.2.3 Self-Harvesting (Migration) Methods .......................................................27 4.2.4 Mechanical Methods ..............................................................................28 4.3 Use of Worms Directly in Agriculture ..........................................................28
5 The Value of Vermicompost ...............................................................................30 5.1 Results from the Literature ........................................................................30 5.2 OACC Trials ..............................................................................................32 5.2.1 Introduction ..........................................................................................32 5.2.2 Indoor Trials .........................................................................................32 5.2.3 Field Trials ............................................................................................33 5.3 Summary: The Value of Vermicompost .......................................................34 OACC Manual of On-Farm Vermicomposting and Vermiculture Page i 6 Other Considerations.........................................................................................35 6.1 Environmental Risks and Benefits...............................................................35 6.1.1 Worms and the Environment ..................................................................35 6.1.2 Water Quality Issues..............................................................................35 6.1.3 Climate Change Factors .........................................................................36 6.1.4 Below-Ground Biodiversity .....................................................................37 6.2 Potential Income Diversification: Worm-related Opportunities for Farmers ....38 6.2.1 Sale of Vermicompost ............................................................................38 6.2.2 Sale of Worms.......................................................................................39 6.2.3 Compost Tea.........................................................................................39 6.2.4 Assessing the Opportunity......................................................................40
Appendix A: References ...........................................................................................A1 Appendix B: Sources of Information..........................................................................B1 Appendix C: Vermiculture Trial – Scott Farm .............................................................C1 Appendix D: Vermicomposting Trials – Holdanca Farms Ltd. and Kipawo Holsteins .... D1 List of Figures
Figure # Title Page # 1 E. fetida - the compost worm 2 2 Initial worm bed on Mentink Farm, OACC Pilot 3 3 Okara used to feed worms on Scott Farm, OACC pilot 7 4 Vermicomposting windrows of shredded cardboard and manure 17 5 Small to medium-scale harvesters 19 6 Cinder-block worm beds on Scott farm 23 7 Framework for stacked bins 24 8 Tomato-plant growth trial at University of Campeche 31 9 Lettuce yield – soil 1 33 10 Lettuce yield – soil 2 33 11 Lettuce yield – field trials 33 C1 Average Population of Treatments after 17 Weeks C1 C2 Average Biomass of Treatments After 17 Weeks C2 C3 Cinderblock & mortar worm bins at Scott Farm C2 C4 A chicken foraging for worms in the vermicompost C2 D1 One of the original worm windrows at Holdanca Farms D1 D2 Biomass change over time – Holdanca Farms D1 D3 Covered compost pad at Kipawo Holsteins D2 D4 Original inside vermi windrow at Kipawo D3 D5 Biomass Increase, Kipawo D3
List of Tables
Table # Title Page # 1 Common Bedding Materials 6 2 Common Worm Feedstocks 8 3 Results of Windrow Tests, Sackville, Nova Scotia 18 OACC Manual of On-Farm Vermicomposting and Vermiculture Page ii 1 Introduction: Vermiculture and Vermicomposting 1.1 The Difference between Vermiculture and Vermicomposting
Vermiculture is the culture of earthworms. The goal is to continually increase the
number of worms in order to obtain a sustainable harvest. The worms are either used to
expand a vermicomposting operation or sold to customers who use them for the same
or other purposes (see “On-Farm Vermiculture” later in this manual).

Vermicomposting is the process by which worms are used to convert organic
materials (usually wastes) into a humus-like material known as vermicompost. The goal
is to process the material as quickly and efficiently as possible.

These two processes are similar but different. If your goal is to produce vermicompost,
you will want to have your maximum worm population density all of the time. If your
goal is to produce worms, you will want to keep the population density low enough that
reproductive rates are optimized. Both of these processes will be described in some
detail in this manual.
1.2 The Compost Worm
There are an estimated 1800 species of earthworm worldwide (Edwards & Lofty, 1972).
This manual will focus on just one. Eisenia fetida (Savigny) is commonly known as
(partial list only): the “compost worm”, “manure worm”, “redworm”, and “red wiggler”
(see Figure 1). This extremely tough and adaptable worm is indigenous to most parts of
the world and can be found on most Canadian farms wherever piles of manure have
been left to age for more than a few months.
Three Types of Earthworm

Anecic (Greek for “out of the earth”) – these are burrowing worms that come to the surface at night to
drag food down into their permanent burrows deep within the mineral layers of the soil. Example: the
Canadian Night crawler.

Endogeic (Greek for “within the earth”) – these are also burrowing worms but their burrows are typically
more shallow and they feed on the organic matter already in the soil, so they come to the surface only
rarely.

Epigeic (Greek for “upon the earth”) – these worms live in the surface litter and feed on decaying organic
matter. They do not have permanent burrows. These “decomposers” are the type of worm used in
vermicomposting.
Information sourced from Card et al., 2004.
Commercially raised worms are usually of the epigeic type. E. fetida is certainly not the
only epigeic worm, but it is the one most often used for composting purposes in
Northern climates. It can handle a wide temperature range (between 0 and 35 o C) and can actually survive for some time almost completely encased in frozen organic material OACC Manual of On-Farm Vermicomposting and Vermiculture Page 1 Fig 1: E. fetida - the compost worm (as long as it can continue to take in
nourishment). Its cocoons (eggs) have been
shown to remain viable after having been frozen
for several weeks 1 . In addition, it can take a lot of handling and rough treatment. Perhaps most
importantly, like most if not all litter-dwelling
worms, the compost worm has the capacity for
very rapid reproduction. This is an evolutionary
necessity for a creature whose natural
environment is extremely changeable and
hazardous and whose natural supplies of food
are of the “boom or bust” variety. All of these
characteristics make E. fetida the natural choice
for those who wish to do their vermicomposting outdoors, year-round, in climates with
harsh winter conditions. 1.3 Why Bother? An Overview of Potential Benefits and Constraints Why should an organic farmer be interested in vermiculture and/or vermicomposting?
The answers are several and may not apply to all organic producers. In summary, they
are as follows:
• Vermicompost appears to be generally superior to conventionally produced compost in a number of important ways; • Vermicompost is superior to most composts as an inoculant in the production of compost teas; • Worms have a number of other possible uses on farms, including value as a high-quality animal feed; • Vermicomposting and vermiculture offer potential to organic farmers as sources of supplemental income.
All of the above will be discussed in detail later in this document. At the same time, the
reader should take note at the beginning that working with worms is a more
complicated process than traditional composting:
• It can be quicker, but to make it so generally requires more labour; • It requires more space because worms are surface feeders and won’t operate in material more than a meter in depth; • It is more vulnerable to environmental pressures, such as freezing conditions and drought; • Perhaps most importantly, it requires more start-up resources, either in cash (to buy the worms) or in time and labour (to grow them). 1 Experiments at Nova Scotia Agricultural College (NSAC) confirmed that the cocoons of E. fetida can survive unprotected freezing for several weeks and remain viable. This species ability, combined with very
high and fast reproduction rates, is what allows these surface-dwelling, non-burrowing worms to thrive in
regions with long, cold winters. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 2 These constraints and disadvantages will also be discussed in detail in the pages that
follow.
Fig 2: Initial worm bed on Mentink Farm, OACC Pilot Because of the benefits described above, and despite these drawbacks, farmers around
the world have started to grow worms and produce vermicompost in rapidly increasing
numbers. Warmer climes have tended to predominate so far, with India and Cuba being
the leaders to date. Vermicomposting centres are numerous in Cuba and vermicompost
has been the largest single input used to replace the commercial fertilizer that became
difficult or even impossible to import after the collapse of the Soviet Union (Cracas,
2000). In 2003, an estimated one million tonnes of vermicompost were produced on the
island (Koont, 2004). In India, an estimated 200,000 farmers practice vermicomposting
and one network of 10,000 farmers 2 produces 50,000 metric tonnes of vermicompost every month. In the past decade, farmers in Australia 3 and the West Coast of the U.S. have started to use vermicompost in greater quantities, fuelling the development of vermicomposting industries in those regions. At the
same time, scientists at several Universities in the
U.S., Canada, India, Australia, and South Africa
have started to document the benefits associated
with the use of vermicompost, providing facts and
figures to support the observations of those who
have used the material.

The Organic Agriculture Centre of Canada
(OACC) has recently completed a pilot project,
funded by Environment Canada’s EcoAction
Program, wherein three Nova Scotia farmers experimented with worms for an 18-month period. The results of their trials provide a
major contribution to this manual. The bottom line is that only the individual producer
will be able to decide whether or not it makes sense to start working with worms. It is
OACC’s hope that this document can be of some assistance to Canadian organic (and
conventional) producers in making that decision. 1.4 What this Manual Can Do for You If you have an interest in working with composting worms, this manual can provide you
with the following:
• A quick course on the basics of growing worms and using them to produce vermicompost . This includes lists of beddings and feed stocks, optimum environmental conditions and how to maintain them, troubleshooting
hints, methods of calculating population increases and product quantities, etc. • An overv ew of vermicomposting systems. These range from simple windrow systems to the flow-through systems used in the United States to i 2 The M.R. Morarka-GDC Rural Research Foundation runs a program that teaches vermiculture and vermicomposting to Indian farmers and also assists them in the development of markets for their product by
guaranteeing a floor price for the material until they find their own buyers at equal or better prices. 3 One of the largest commercial producers of vermicompost is Vermitech Pty Ltd of Australia. Their website – http://www.vermitech.com --documents considerable research on the use of their product on various crops. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 3 produce high-quality bagged product for the home-gardening market. Basic
descriptions and instructions are included. • A summary of what is known regarding the value of vermicompost. This summary includes information from the literature as well as data gathered by
OACC and NSAC through recent plant-growth trials. • Information on the inherent value of the worms themselves , both in agriculture and as a source of protein for animal feed. • A discussion of opportunities for farmers to make money with worms. Examples of successful on-farm businesses are presented, along with some
guidelines on the pitfalls associated with the business of vermicomposting. • An overview of environmental considerations. The environmental pros and cons are discussed; in particular, the potential for mitigation of climate change is
considered. • Criteria for opportunity assessment. This is a series of questions and associated criteria for farmers to use in assessing the opportunities associated
with worms. • A resource list -- credible sources of information on vermiculture and vermicomposting.
OACC believes that the reader should approach the entire concept of working with
composting worms with a pragmatic bent and a skeptical mind. While there do appear
to be significant opportunities, there also appears to be a lot of hype. In addition, the
vermiculture industry in the United States has a 40-year history of scams and pyramid-
style buy-back schemes that have relieved many innocent but naïve people of their life
savings. This manual has been designed to help the reader get an accurate sense of
what worms can offer a producer, what levels of effort and resources are required, and
what associated risks are involved.













OACC Manual of On-Farm Vermicomposting and Vermiculture Page 4 2 Working with Worms: The Basics 2.1 What Worms Need 2.1.1 The Five Essentials Compost worms need five basic things:
1 An hospitable living environment, usually called “bedding”; 2 A food source; 3 Adequate moisture (greater than 50% water content by weight); 4 Adequate aeration; 5 Protection from temperature extremes.
These five essentials are discussed in more detail below. 2.1.2 Bedding Bedding is any material that provides the worms with a relatively stable habitat. This
habitat must have the following characteristics: • High absorbency. Worms breathe through their skins and therefore must have a moist environment in which to live. If a worm’s skin dries out, it dies. The
bedding must be able to absorb and retain water fairly well if the worms are to
thrive. • Good bulking potential. If the material is too dense to begin with, or packs too tightly, then the flow of air is reduced or eliminated. Worms require oxygen
to live, just as we do. Different materials affect the overall porosity of the
bedding through a variety of factors, including the range of particle size and
shape, the texture, and the strength and rigidity of its structure. The overall
effect is referred to in this document as the material’s bulking potential. • Low protein and/or n trogen content (high Carbon: Nitrogen ratio). Although the worms do consume their bedding as it breaks down, it is very
important that this be a slow process. High protein/nitrogen levels can result in
rapid degradation and its associated heating, creating inhospitable, often fatal,
conditions. Heating can occur safely in the food layers of the vermiculture or
vermicomposting system, but not in the bedding. i
Some materials make good beddings all by themselves, while others lack one or more of
the above characteristics and need to be used in various combinations. Table 1 provides
a list of some of the most commonly used beddings and provides some input regarding
each material’s absorbency, bulking potential, and carbon to nitrogen (C:N) ratios. OACC
tested the first two materials in Table 1 – horse manure and peat moss – in a separate
experiment within the EcoAction-funded pilot project in 2003-2004. Both materials
performed well, with the horse manure having the edge. Since horse manure was
available free of charge and is a renewable resource, it was used in the balance of the
trial (See Appendix C for a full description of this experiment). If available, it is generally
considered to be an ideal bedding. Its high C:N ratio (for a manure), good bulking
characteristics (because of the high straw content), and relatively good moisture
retention make it an excellent environment for E. fetida. It can be improved somewhat OACC Manual of On-Farm Vermicomposting and Vermiculture Page 5 by the addition of a high-absorbency material such as peat moss or shredded
paper/cardboard (which will increase absorbency and also increase the C:N ratio a bit –
another positive).

Table 1: Common Bedding Materials

Bedding Material Absorbency Bulking Pot. C:N Ratio 4 Horse Manure Medium-Good Good 22 - 56 Peat Moss Good Medium 58 Corn Silage Medium-Good Medium 38 - 43 Hay – general Poor Medium 15 - 32 Straw – general Poor Medium-Good 48 - 150 Straw – oat Poor Medium 48 - 98 Straw – wheat Poor Medium-Good 100 - 150 Paper from municipal waste stream Medium-Good Medium 127 - 178 Newspaper Good Medium 170 Bark – hardwoods Poor Good 116 - 436 Bark -- softwoods Poor Good 131 - 1285 Corrugated cardboard Good Medium 563 Lumber mill waste -- chipped Poor Good 170 Paper fibre sludge Medium-Good Medium 250 Paper mill sludge Good Medium 54 Sawdust Poor-Medium Poor-Medium 142 - 750 Shrub trimmings Poor Good 53 Hardwood chips, shavings Poor Good 451 - 819 Softwood chips, shavings Poor Good 212 - 1313 Leaves (dry, loose) Poor-Medium Poor-Medium 40 - 80 Corn stalks Poor Good 60 - 73 Corn cobs Poor-Medium Good 56 - 123
If available, shredded paper or cardboard makes an excellent bedding (GEORG, 2004),
particularly when combined with typical on-farm organic resources such as straw and
hay. Organic producers, however, must be careful to ensure that such materials are not
restricted under their organic certification standards. Paper or cardboard fibre collected
in municipal waste programs cannot be approved for certification purposes. There may
be cases, however, where fibre resources from specific generators could be sourced and
approved. This must be considered on a case-by-case basis. Another material in this
category is paper-mill sludge (Elvira et al., 1996; 1997), which has the high absorbency
and small particle size that so well complements the high C:N ratios and good bulking
properties of straw, bark, shipped brush or wood shavings. Again, the sludge must be
approved if the user has organic certification.
4 Most of the C:N ratios were obtained from The On-Farm Composting Handbook (see Sources and Reference Sections); the balance were obtained from the other sources listed under References. The former
document also compiled the ratios from reports in the literature. The averages or ranges quoted, therefore,
are estimates and intended only to provide the reader with a general sense of how each material compares
to the others with respect to nitrogen content. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 6 In general, it should be noted by the reader that the selection of bedding materials is a
key to successful vermiculture or vermicomposting. Worms can be enormously
productive (and reproductive) if conditions are good; however, their efficiency drops off
rapidly when their basic needs are not met (see discussion on moisture below). Good
bedding mixtures are an essential element in meeting those needs. They provide
protection from extremes in temperature, the necessary levels and consistency of
moisture, and an adequate supply of oxygen. Fortunately, given their critical importance
to the process, good bedding mixtures are generally not hard to come by on farms. The
most difficult criterion to meet adequately is usually absorption, as most straws and
even hay are not good at holding moisture. This can be easily addressed by mixing
some aged or composted cattle or sheep manure with the straw. The result is somewhat
similar in its bedding characteristics to aged horse manure.

Mixing beddings need not be an onerous process; it can be done by hand with a
pitchfork (small operations), with a tractor bucket (larger operations), or, if one is
available, with an agricultural feed mixer. Please note that the latter would only be
appropriate for large commercial vermicomposting operations where high efficiency
levels and consistent product quality is required.

Some of these materials also have revenue-generating potential, through commercial
tipping fees. This aspect of vermicomposting and vermiculture is discussed in more
detail in Section 6. 2.1.3 Worm Food Fig 3: Okara (waste from tofu produc- tion) used to feed worms on Scott Farm, OACC pilot (see Appendix C). 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 5 . They will eat almost anything organic (that is, of plant or animal origin), but they definitely prefer some foods to others. Manures are the most
commonly used worm feedstock, with
dairy and beef manures generally
considered the best natural food for
Eisenia, with the possible exception of
rabbit manure (Gaddie & Douglas, 1975).
The former, being more often available in
large quantities, is the feed most often
used.

Table 2 summarizes the most important
attributes of some of the more common
foods that could be used in an on-farm
vermicomposting or vermiculture
operation. Please note that the provision
of instructions for composting high-protein
wastes (e.g., animal mortalities) is beyond
5 The actual amount of food that can be consumed daily by Eisenia fetida varies with a number of factors, not the least of which is the state of decomposition of the food. Manures, which consist of partially
decomposed organic material, can be consumed more rapidly than fresh food, and some studies have found
that worms can exceed their own weight in daily consumption of manure. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 7 the scope of this manual. For more information on this aspect of on-farm waste
management, see Resources in Section 8. More detail on vermicomposting methods is provided in Section 3.

Table 2: Common Worm Feed Stocks
Food Advantages Disadvantages Notes Cattle manure Good nutrition; natural food, therefore little
adaptation req’d Weed seeds make pre-composting
necessary All manures are partially decomposed and thus ready
for consumption by worms Poultry manure High N content results in good nutrition and a high-value product High protein levels can be dangerous to worms, so must be
used in small quantities; major adaptation required for worms not used to this feedstock. May be pre-composted but
not necessary if used cautiously (see Notes) Some books (e.g., Gaddie & Douglas, 1975) suggest that poultry manure is not suitable
for worms because it is so “hot”; however, research in Nova Scotia (GEORG, 2004) has shown that worms can adapt if initial proportion of PM to bedding is 10% by
volume or less. Sheep/Goat manure Good nutrition Require pre- composting (weed
seeds); small particle size can lead to packing, necessitating extra bulking material With right additives to increase C:N ratio, these
manures are also good beddings Hog manure Good nutrition; produces excellent vermicompost Usually in liquid form, therefore must be dewatered or used with large quantities of highly absorbent
bedding Scientists at Ohio State University found that vermicompost made with hog manure outperformed all other vermicomposts, as well
as commercial fertilizer Rabbit manure N content second only to poultry manure, there- fore good nutrition;
contains very good mix of vitamins & minerals; ideal earth-worm feed (Gaddie, 1975) Must be leached prior to use because of high urine content;
can overheat if quantities too large; availability usually not good Many U.S. rabbit growers place earthworm beds under their rabbit hutches to catch
the pellets as they drop through the wire mesh cage floors. Fresh food scraps (e.g., peels, other food prep waste, leftovers, commercial food processing
wastes) Excellent nutrition, good moisture content, possibility of revenues from waste tipping fees Extremely variable (depending on source); high N can result in overheating; meat & high-fat wastes can create
anaerobic conditions and odours, attract pests, so should NOT be included without pre-composting (see below) Some food wastes are much better than others: coffee grounds are excellent, as they are high in N, not greasy or smelly, and are attractive to worms; alternatively, root
vegetables (e.g., potato culls) resist degradation and require a long time to be consumed. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 8 Food Advantages Disadvantages Notes Pre-composted food wastes Good nutrition; partial decomposition makes digestion by worms easier and faster; can include meat and other greasy wastes; less
tendency to overheat. Nutrition less than with fresh food wastes (Frederickson et al, 1997). Vermicomposting can speed the curing process for conventional composting operations while increasing value of end product (GEORG, 2004; Frederickson, op. cit.) Biosolids (human waste) Excellent nutrition and excellent product; can be activated or non-
activated sludge, septic sludge; possibility of waste management revenues Heavy metal and/or chemical contam- ination (if from
municipal sources); odour during application to beds (worms control fairly quickly); possibility of pathogen survival if
process not complete Vermitech Pty Ltd. in Australia has been very successful with this process, but they use
automated systems; EPA- funded tests in Florida demonstrated that worms destroy human pathogens as well as does thermophillic composting (Eastman et al.,
2000). Seaweed Good nutrition; results in excellent product, high in micronutrients and
beneficial microbes Salt must be rinsed off, as it is detrimental to worms; availability
varies by region Beef farmer in Antigonish, NS, producing certified organic vermicompost from cattle
manure, bark, and seaweed 6 Legume hays Higher N content makes these good feed as well as reasonable bedding. Moisture levels not as high as other feeds, requires more input
and monitoring Probably best to mix this feed with others, such as manures Grains (e.g., feed mixtures for animals, such as
chicken mash) Excellent, balanced nutrition, easy to handle, no odour, can use
organic grains for certified organic product Higher value than most feeds, therefore expensive to use; low
moisture content; some larger seeds hard to digest and slow to break down Danger: Worms consume grains but cannot digest larger, tougher kernels; these
are passed in castings and build up in bedding, resulting in sudden overheating (Gaddie, op cit) Corrugated cardboard (including waxed) Excellent nutrition (due to high-protein glue used to hold layers together); worms like this material; possible
revenue source from WM fees Must be shredded (waxed variety) and/or soaked (non- waxed) prior to feeding Some worm growers claim that corrugated cardboard stimulates worm reproduction Fish, poultry offal; blood
wastes; animal mortalities High N content provides good nutrition;
opportunity to turn problematic wastes into high-quality product MUST be pre- composted until past
thermophillic stage Composting of offal, blood wastes, etc. is difficult and
produces strong odours. Should only be done with in- vessel systems; much bulking required. 6 See www.atlanticcountrycomposting.com. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 9 2.1.4 Moisture The need for adequate moisture was discussed in relation to bedding in Section 2.1.2
above. The bedding used must be able to hold sufficient moisture if the worms are to
have a livable environment. They breathe through their skins and moisture content in
the bedding of less than 50% is dangerous. With the exception of extreme heat or cold,
nothing will kill worms faster than a lack of adequate moisture.

The ideal moisture-content range for materials in conventional composting systems is
45-60% (Rink et al, 1992). In contrast, the ideal moisture-content range for
vermicomposting or vermiculture processes is 70-90%. Within this broad range,
researchers have found slightly different optimums: Dominguez and Edwards (1997)
found the 80-90% range to be best, with 85% optimum, while Nova Scotia researchers
found that 75-80% moisture contents produced the best growth and reproductive
response (GEORG, 2004). Both of these studies found that average worm weight
increased with moisture content (among other variables), which suggests that
vermiculture operations designed to produce live poultry feed or bait worms (where
individual worm size matters) might want to keep moisture contents above 80%, while
vermicomposting operations could operate in the less mucky 70-80% range. 2.1.5 Aeration Worms are oxygen breathers and cannot survive anaerobic conditions (defined as the
absence of oxygen). When factors such as high levels of grease in the feedstock or
excessive moisture combined with poor aeration conspire to cut off oxygen supplies,
areas of the worm bed, or even the entire system, can become anaerobic. This will kill
the worms very quickly. Not only are the worms deprived of oxygen, they are also killed
by toxic substances (e.g., ammonia) created by different sets of microbes that bloom
under these conditions. This is one of the main reasons for not including meat or other
greasy wastes in worm feedstock unless they have been pre-composted to break down
the oils and fats.

Although composting worms O 2 requirements are essential, however, they are also relatively modest. Worms survive harsh winters inside windrows where all surfaces are
frozen: they live on the oxygen available in the water trapped inside the windrow.
Worms in commercial vermicomposting units can operate quite well in their well
insulated homes as long as there are small cracks or openings for ventilation somewhere
in the system. Nevertheless, they operate best when ventilation is good and the material
they are living in is relatively porous and well aerated. In fact, they help themselves in
this area by aerating their bedding by their movement through it. This can be one of the
major benefits of vermicomposting: the lack of a need to turn the material, since the
worms do that work for you. The trick is to provide them with bedding that is not too
densely packed to prevent this movement (see discussion of beddings in Section 2.1.2
above). 2.1.6 Temperature Control Controlling temperature to within the worms’ tolerance is vital to both vermicomposting
and vermiculture processes. This does not mean, however, that heated buildings or
cooling systems are required. Worms can be grown and materials can be OACC Manual of On-Farm Vermicomposting and Vermiculture Page 10 vermicomposted using low-tech systems, outdoors and year-round, in the more
temperate regions of Canada 7 . Section 3 discusses the different vermicomposting and vermiculture systems in use world-wide and provides some basic information on how
these systems address the problem of temperature control. The following points are
general and are intended to provide background for the more system-specific
information in Section 3.
• Low temperatures. Eisenia can survive in temperatures as low as 0 o C, but they don’t reproduce at single-digit temperatures and they don’t consume as
much food. It is generally considered necessary to keep the temperatures above
10 o C (minimum) and preferably 15 o C for vermicomposting efficiency and above 15 o C (minimum) and preferably 20 o C for productive vermiculture operations. • Effects of freezing. Eisenia can survive having their bodies partially encased in frozen bedding and will only die when they are no longer able to consume
food 8 . Moreover, tests at the Nova Scotia Agricultural College (NSAC) have confirmed that their cocoons survive extended periods of deep freezing and
remain viable (GEORG, 2004). • High temperatures. Compost worms can survive temperatures in the mid-30s but prefer a range in the 20s ( o C). Above 35 o C will cause the worms to leave the area. If they cannot leave, they will quickly die. In general, warmer
temperatures (above 20 o C) stimulate reproduction. • Worms’s response to temperature differentials. Compost worms will redistribute themselves within piles, beds or windrows according to temperature
gradients. In outdoor composting windrows in wintertime, where internal heat
from decomposition is in contrast to frigid external temperatures, the worms will
be found in a relatively narrow band at a depth where the temperature is close
to optimum. They will also be found in much greater numbers on the south-
facing side of windrows in the winter and on the opposite side in the summer. 2.2 Other Important Parameters
There are a number of other parameters of importance to vermicomposting and
vermiculture:

pH. Worms can survive in a pH range of 5 to 9 (Edwards, 1998). Most experts feel that
the worms prefer a pH of 7 or slightly higher. Nova Scotia researchers found that the
range of 7.5 to 8.0 was optimum (GEORG, 2004). In general, the pH of worm beds
tends to drop over time. If the food sources are alkaline, the effect is a moderating one,
tending to neutral or slightly alkaline. If the food source or bedding is acidic (coffee
grounds, peat moss) than the pH of the beds can drop well below 7. This can be a
problem in terms of the development of pests such as mites. The pH can be adjusted 7 It may also be possible to grow worms outdoors in Canada’s far north (e.g., the Territories and northern regions of BC, the Prairies, Ontario, Quebec, Labrador), but OACC has no experience or knowledge
in these areas. 8 The author has found live worms almost completely encased in frozen bedding/castings mixtures, with only their heads free to move. Upon thawing, these worms have appeared perfectly healthy. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 11 upwards by adding calcium carbonate. In the rare case where they need to be adjusted
downwards, acidic bedding such as peat moss can be introduced into the mix.

Salt content. Worms are very sensitive to salts, preferring salt contents less than 0.5%
(Gunadi et al., 2002). If saltwater seaweed is used as a feed (and worms do like all
forms of seaweed), then it should be rinsed first to wash off the salt left on the surface.
Similarly, many types of manure have high soluble salt contents (up to 8%). This is not
usually a problem when the manure is used as a feed, because the material is usually
applied on top, where the worms can avoid it until the salts are leached out over time by
watering or precipitation. If manures are to be used as bedding, they can be leached
first to reduce the salt content. This is done by simply running water through the
material for a period of time (Gaddie, 1975). If the manures are pre-composted
outdoors, salts will not be a problem.

Urine content. Gaddie and Douglas (1975) state: “If the manure is from animals raised
or fed off in concrete lots, it will contain excessive urine because the urine cannot drain
off into the ground. This manure should be leached before use to remove the urine.
Excessive urine will build up dangerous gases in the bedding. The same fact is true of
rabbit manure where the manure is dropped on concrete or in pans below the cages.”.

Other toxic components. Different feeds can contain a wide variety of potentially
toxic components. Some of the more notable are: • De-worming medicine in manures, particularly horse manure. Most modern deworming medicines break down fairly quickly and are not a problem for worm
growers. Nevertheless, if using manure from another farm than your own, it
would be wise to consult your source with regard to the timing of de-worming
activities, just to be sure. Application of fresh manure from recently de-wormed
animals could prove costly. • Detergent cleansers industrial chemicals, pesticides. These can often be found in feeds such as sewage or septic sludge, paper-mill sludge, or some food
processing wastes. , • Tannins . Some trees, such as cedar and fir, have high levels of these naturally occurring substances. They can harm worms and even drive them from the beds
(Gaddie, op. cit.). Gunadi et al. (2002) point out that pre-composting of wastes can reduce or even
eliminate most of these threats. However, pre-composting also reduces the nutrient
value of the feed, so this is a definite trade-off. 2.3 Calculating Rates of Reproduction Epigeic worms such as E. fetida do reproduce very quickly, given good to ideal
conditions. Compost worm populations can be expected to double every 60 to 90 days,
but only if the following conditions are met:
• Adequate food (must be continuous supply of nutritious food, such as those listed in Table 2); • Well aerated bedding with moisture content between 70 and 90%; • Temperatures maintained between 15 and 30 o C; OACC Manual of On-Farm Vermicomposting and Vermiculture Page 12 • Initial stocking densities greater than 2.5 kg/m 2 (0.5 lb/ft 2 ) but not more than 5 kg/m 2 (1.0 lb/ft 2 ).
The issues of food, aeration, moisture and temperature are discussed in Section 2.1
above. The issue of initial stocking density, however, was not discussed previously and
requires elaboration here. Stocking density refers to the initial weight of worm biomass
per unit area of bedding. For instance, if you started with 5 kg of worms and put them
in a bin with a surface area of 2 m 2 , then your initial stocking density would be 2.5 kg/m 2 . Starting with a population density less than this will delay the onset of rapid reproduction and, at very low densities, may even stop it completely. It seems that
worms need a certain density in order to have a reasonable chance of running into each
other and reproducing frequently. At lower densities, they just don’t find each other as
often as the typical worm grower would like.

On the other hand, densities higher than 5 kg/m 2 begin to slow the reproductive urge, as competition for food and space increase. While it is possible to get worm densities up
to as much as 20 kg/m 2 or 4 lbs per square foot (Edwards, 1999), the most common densities for vermicomposting are between 5 and 10 kg/m 2 (1 to 2 lbs per ft 2 ). Worm growers tend to stock at 5 kg/m 2 (Bogdanov, 1996) and “split the beds” when the density has doubled, assuming that the optimum densities for reproduction have by that
point been surpassed.

If the above guidelines are followed, a grower can expect a doubling in worm biomass
about every 60 days. Theoretically, this means that an initial stock of 10 kg of worms
can become 640 kg after one year and about 40 tonnes after two years. In practice, this
is difficult to achieve, though not impossible. For instance, American Resource Recovery,
a recycling firm in northern California, started with 50 pounds of earthworms. In four
years, they had enough to cover over 70 acres of windrows, within which the worms
convert huge quantities of sludge from a cardboard recycling plant into worm castings
(VermiCo, 2004). On the other hand, OACC’s three pilot projects accomplished in total
only a 10-fold biomass increase over 12 months 9 , when in theory the increase should have been by a factor of 64. The factors that kept this number lower than optimum
included various problems with bedding, feed, moisture, and temperature control. These
are documented in Appendices C and D.

The main barriers to achieving optimum rates of reproduction appear to be the
following:
• Lack of knowledge and experience . Growing worms is part science, part “green thumb”. You need the knowledge (as in this Manual), but you also need
to do it to learn how to do it well. • Lack of dedicated resources . Increasing worm populations requires paying attention to what is happening and responding accordingly. This takes time and
effort. If the beds or windrows are neglected, the worms will likely survive, but
the population will not increase at an optimum rate. 9 It should be noted that in one of the trials (Scott farm) the worms were being harvested, so the rate of increase was lower than it would have been were this not the case. The other two farms averaged
increases closer to a factor of 12 and were increasing the rate of increase towards the end of the trials . OACC Manual of On-Farm Vermicomposting and Vermiculture Page 13 • Lack of preparation for winter. Although harsh winter conditions are unlikely to completely destroy a worm population 10 , they can (as in the OACC pilot project) reduce the rate of increase considerably. The various vermicomposting
and vermiculture systems have different ways of dealing with this problem.
These are addressed in Section 3. 2.4 Projecting Vermicompost Outputs
In the world of conventional composting, the rule-of-thumb is that one ton of inputs
results in one cubic yard of compost, the weight of which varies with moisture content
but is typically about ½ ton. In other words, 50% of the mass is lost, mostly as moisture
and CO 2 . Some N is lost as ammonia, but if the process is well managed the N loss is minimized (Rink et al, 1992). Of course, the final weight and volume of product varies
with original feedstock, bulking agent used, etc., but the above rule-of-thumb is a handy
way to quickly calculate output.

Vermicomposting is a bit more variable. This is because there is more variation in how
the process is carried out. In composting, mixtures of high-N and high-C materials are
made at the start and nothing is added to the mix thereafter. C:N ratios are calculated
at the beginning and these fall as C is lost during the process in greater proportion than
is N. In vermicomposting or vermiculture operations, the high-C materials are used as
bedding, while the high-N materials are generally feed stocks. Although similar
processes are taking place in the bed (including conventional composting due to the
action of micro-organisms), some systems encourage the addition over the course of the
process of greater amounts of N relative to C than would be the case with conventional
composting. This is because the feeds are added to the surface of the pile or windrow
incrementally, rather than mixed in at the beginning. Since some high-N materials (e.g.,
fresh food wastes) can be higher in initial water content than high-C bedding materials,
weight losses during the vermicomposting process can be higher. In one flow-through
system 11 for vermicomposting fresh food wastes tested in Nova Scotia, the total system output was about 10% of the inputs by weight. Another factor reducing final output
quantities in vermicomposting is the amount of material converted into worm biomass.
This material is largely lost to the final product because most of the worms are removed
from the product prior to completion of the process. Alternatively, vermicomposting
processes can also allow for higher amounts of overall C to be processed. For instance,
shredded paper and cardboard can be converted into vermicompost with the addition of
as little as 5% poultry manure, by volume (GEORG, 2004). The result of this process is a
product weight closer to 50% of the initial input weight.
10 The ability of worm populations to regenerate from cocoons after complete decimation of the stock through freezing has been documented in Nova Scotia. In one experiment conducted by Good Earth, 1-ft-
high windrows of shredded cardboard and coffee grounds were established in late summer in an unheated
building on an asphalt floor. The windrows froze completely through in the winter and no worms were found
in early spring. Because the floor was paved, there was no way for the worms to escape into the earth. By
July of the same year, the worm population was back to vermicomposting levels (at least 5 kg/m2) and the
material was fully processed (GEORG, 2004). 11 Flow-through systems allow food to be added to the surface indefinitely, while product is removed from below. See Section 3 for a detailed definition and decsription. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 14 In general, outputs from vermicomposting processes can vary from about 10% to closer
to 50% of the original weight of the inputs. This will vary with the nature of the inputs
and the system used. The greater the proportion of high-C inputs to high-N inputs, the
greater will be the weight of final output as a proportion of input weight.

If estimating the amount of output is important, it can be tested by running a bench or
pilot-scale trial for several months. 2.5 Pests and Diseases
Compost worms are not subject to diseases caused by micro-organisms, but they are
subject to predation by certain animals and insects (red mites are the worst) and to a
disease known as “sour crop” caused by environmental conditions. The following is a
brief overview of the most common pests and diseases likely to be experienced in
Canada.
• Moles. Earthworms are moles’ natural food, so if a mole gets access to your worm bed, you can lose a lot of worms very quickly (Gaddie, op. cit.). This is
usually only a problem when using windrows or other open-air systems in fields.
It can be prevented by putting some form of barrier, such as wire mesh, paving,
or a good layer of clay, under the windrow. • Birds. They are not usually a major problem, but if they discover your beds they will come around regularly and help themselves to some of your workforce.
Putting a windrow cover of some type over the material will eliminate this
problem. These covers are also useful for retaining moisture and preventing too
much leaching during rainfall events. Old carpet can be used for this purpose
and is very effective 12 . • Centipedes. These insects eat compost worms and their cocoons. Fortunately, they do not seem to multiply to a great extent within worm beds or windrows, so
damage is usually light. If they do become a problem, one method suggested for
reducing their numbers is to heavily wet (but not quite flood) the worm beds.
The water forces centipedes and other insect pests (but not the worms) to the
surface, where they can be destroyed by means of a hand-held propane torch or
something similar (Gaddie, op. cit.; Sherman, 1997). • Ants. These insects are more of a problem because they consume the feed meant for the worms (Myers, 1969). Ants are particularly attracted to sugar, so
avoiding sweet feeds in the worm beds reduces this problem to a minor one.
Keeping the bedding above pH 7 also helps (see mites and sour crop below). • Mites. There are a number of different types of mites that appear in vermiculture and vermicomposting operations, but only one type is a serious
problem: red mites. White and brown mites compete with worms for food and
can thus have some economic impact, but red mites are parasitic on
earthworms. They suck blood or body fluid from worms and they can also suck
fluid from cocoons (Sherman, 1997). The best prevention for red mites is to • 12 Make sure that the carpet does not have a non-breathable synthetic backing. Also, note that the carpet will eventually break down and be consumed by the worms. This process takes a
long time, however, and is a better fate for old carpet than the landfill. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 15 make sure that the pH stays at neutral or above. This can be done by keeping
the moisture levels below 85% and through the addition of calcium carbonate, as
required. • Sour crop or protein poisoning. This “disease” is actually the result of too much protein in the bedding. This happens when the worms are overfed. Protein
builds up in the bedding and produces acids and gases as it decays (Gaddie, op.
cit.). According to Ruth Myers (1969): “when you see a worm with a swollen
clitellum 13 or see one crawling aimlessly around on top of the bedding, you can just bet on sour crop and act accordingly, but fast”. Her recommended solution is
a “massive dose of one of the mycins, such as farmers give to chicken or cattle”.
Farmers wishing to avoid these or similar antibiotics should work to prevent sour
crop by not overfeeding and by monitoring and adjusting pH on a regular basis.
Keeping the pH at neutral or above will preclude the need for these measures. 13 The clitellum is the noticeable band around earthworms bodies, closer to the head than the tail. These are used in the reproductive process. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 16 3 An Overview of Vermicomposting Systems 3.1 Basic Types of Systems OACC Manual of On-Farm Vermicomposting and Vermiculture Page 17 Batch vs Continuous-Flow Systems

Batch systems are ones in which the bedding and food are mixed, the worms added, and nothing more is done (except by the worms!) until the process is complete. Continuous-flow systems are ones in which worms are placed
bedding, whereupon feed and new bedding ar added incrementally on a regular in e basis. There are three basic types of
vermicomposting systems of interest to
farmers: windrows, beds or bins, and
flow-through reactors. Each type has
a number of variants. Windrows and bins
can be either batch or continuous-flow
systems (see box), while all flow-through
systems, as the name suggests, are of
the continuous-flow variety. 3.2 Windrows Windrow vermicomposting can be carried out in a number of different ways. The three
most common are described here. 3.2.1 Static pile windrows (batch) Static pile windrows are simply piles of mixed bedding and feed (or bedding with feed
layered on top) that are inoculated with worms and allowed to stand until the processing
is complete. These piles are usually elongated in a windrow style but can also be
squares, rectangles, or any other shape that makes sense for the person building them.
They should not exceed one meter in height (before settling). Care must be taken to
provide a good environment for the worms, so the selection of bedding type and
amount is important (see Section 2.1.2). In the OACC vermicomposting trials (see
Appendix D), the original selection of aged dairy manure as bedding turned out to be a
poor choice, and initial worm reproduction was quite slow. After the bedding was
supplemented with large quantities of hay and silage, increasing the porosity of the
windrows, worm reproduction took off.

In another
example, the
author was part of
a Nova Scotia
team of
researchers that
experimented with
static windrows in
2003-4, using
shredded
municipally
collected fibre
(boxboard,
cardboard, etc.) as
bedding and cattle Figure 4: Vermicomposting windrows of shredded cardboard and manure and poultry manures as feedstock. The materials were mixed by turning with a tractor
bucket, in ratios of 1:9 and 1:19 (poultry manure to shredded fibre) and 1:2 (cattle
manure to shredded fibre). They were laid down in windrows that were initially one
meter in height, three meters wide, and 50 meters long (see Figure 4). The windrows
were inoculated by placing them directly on top of smaller windrows (30 cm high by 1
meter across) that were composed of worm-rich compost. The windrows were
established in late August of 2003; they were not covered or protected from the cold.
They sat on a clay base that provided no underground escape option for the worms.

By late autumn, the windrows had settled and been reduced in volume through the
action of the worms and composting bacteria to about one half of their original height.
Worm populations were increasing rapidly. Winter arrived in December and, by Nova
Scotia standards, it was a very cold one, with temperatures staying well below zero and
with little snow cover until mid-February, when a blizzard dropped about a meter of
snow in 36 hours. Thawing occurred over March and early April.

Initial sampling (April 22, 2003) revealed that worm populations were down significantly,
but that some adult worms and many cocoons had survived. By July, all the test
windrows had large, active worm populations, but there were significant differences in
performance between the different feed stocks (see Table 3). The best performance was
obtained from the 1:9 mixture of cardboard to poultry manure. Worm biomass had
increased by a factor of five and the material was almost completely composted (only
the material exposed to the air on the surface was not processed). The material from
this windrow was used for plant-growth trials at NSAC and performed very well (see
Section 5, below).

Table 3: Results of Windrow Tests, Sackville, Nova Scotia (GEORG, 2004)

Test mixture Increase in worm
biomass at peak 1 Amount of original material
processed at peak biomass 2 Cattle manure (33%) 1.65x 25-35% Poultry manure (5%) 2.56x 40-50% Poultry manure
(10%) 5.0x 90-95% Notes on data in table:
1 The “worm biomass at peak” data represents the estimated worm biomass at its highest point in the
summer of 2004, prior to eventual decline due to decreasing availability of food.
2 The “amount of original material processed at peak biomass” represents the estimated percentage of the
material that was converted into vermicompost by the time the worm populations peaked (after 45-50
weeks). Note that the 10%-poultry-manure treatment was the only one that provided sufficient nutrition to
allow worm populations to grow large enough to complete processing before worm biomass started to
decrease. This does not mean that the other material was not eventually processed; worm biomass levels
continued to decline but the material continued to be processed, albeit much more slowly.
In summary, the tests showed that static vermicomposting windrows can work in a
Canadian climate, but that the winter reduces efficiency, resulting in slower processing
times than would be experienced indoors. Similar windrows could be established on
farms, using horse manure, silage, and other high-carbon materials as bedding and OACC Manual of On-Farm Vermicomposting and Vermiculture Page 18 mixing them with a high-nitrogen feedstock such as poultry manure, seaweed, or
partially pre-composted food wastes. Once established, the worm populations can be
maintained by laying the following year’s windrows each spring adjacent to the
established ones and allowing the worms to migrate to the fresher material over the
course of the summer. The older windrows can then be removed in the fall and the
vermicompost utilized right away or stored for use the following spring.

The following points are important to keep in mind if establishing such a system on a
farm.
1 Although the windrows do not need to be turned, they will need to be either watered or covered. The worms prefer that the moisture content be above 70% and will not thrive much below 60%. As an alternative
to watering, moisture can be conserved by covering the windrows. Although
it is preferable to use a material that breathes (old carpet or burlap works
beautifully), a few holes in a plastic sheet will allow enough air in to keep the
worms healthy. If the material is very wet (> 80%) when the windrows are
established, a good cover will keep the moisture levels high enough to get
the job done. If your area gets a fair bit of rain, a carpet covering will work
best, as it allows some precipitation to come through into the material; if it
does not, plastic may be better, as it will retain the original moisture for a
longer period of time. Both will prevent large-scale leaching of the nutrients
into the ground beneath. 2 Areas with extremely cold winters, such as the Prairies, should try this on a small scale initial y . The results obtained in Nova Scotia should hold for the other Atlantic Provinces and the southern parts of Ontario,
Quebec, and BC. Whether the worms in
windrows such as those described above
can withstand an Alberta winter and
come back in the spring remains to be
seen. These areas can certainly use
some of the other methods (see below),
but should try this approach out on an
inexpensive scale first. It is also possible
to protect the windrows to some extent
by adding layers of straw or other
insulating material. Of course, this is
more work, but in combination with a
high-nitrogen feedstock it can work quite
well in even very cold winters l 14 . 3 Don’t be afraid to load up on the
nitrogen. As long as the worms have an
area into which they can retreat (e.g., a base of maybe 20 cm of bedding
only, no feed), you can add fairly high quantities of nitrogen-rich feed in the Fig 5: Small to medium-scale
harvesters such as this one can
be used to harvest hundreds of pounds of worms per day. 14 One farmer in Nova Scotia covers his windrows with a foot or so of straw followed by sheets of black plastic with holes punched in it to allow some airflow. This has worked very well for
him: he has not lost any processing time and his worm populations have always increased
considerably over the winters. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 19 overall mix. This is especially true if you set up the windrows in the fall. The
high-nitrogen material will create thermophillic conditions that will help to
keep the worms warm over the winter. In fact, some worm growers in
northern climes set up their windrows in fall with a core of high-nitrogen
“fuel” to keep the temperatures above freezing all winter. The worms will
move into the nitrogen-rich areas as the temperatures gradually decline.
Having sufficient nitrogen in the mix is necessary to ensure that the worms
will have sufficient nutrition to get the job done. 4 Harvesting. One of the major advantages that conventional composting
has over vermicomposting is that in the former there is no need to separate
the workers from the product. The aerobic bacteria that do most of the work
in a composting windrow can be safely ignored when it comes time to spread
the finished product on a field or screen it and put it in a bag. Not so with
worms: they take too long to reproduce (compared to bacteria) and thus are
much too expensive to abandon with each load of product. In batch systems
such as windrows, it is necessary to either run the product through a worm
harvester (see Figure 5), or set up the next batch of windrows in such a way
that the worms can leave of their own accord (see description on the
previous page). Neither system is perfect and worms are always lost;
however, if done properly, either system will leave enough worms to keep
the system working and probably also enough to gradually expand it over
time to accommodate larger volumes of materials. 3.2.2 Top-fed windrows (continuous flow)
Top-fed windrows are similar to the windrows described above, except that they are not
mixed and placed as a batch, but are set up as a continuous-flow operation. This means
that the bedding is placed first, then inoculated with worms, and then covered
repeatedly with thin (less than 10 cm) layers of food. The worms tend to consume the
food at the food/bedding interface, then drop their castings near the bottom of the
windrow. A layered windrow is created over time, with the finished product on the
bottom, partially consumed bedding in the middle, and the fresher food on top. Layers
of new bedding should be added periodically to replace the bedding material gradually
consumed by the worms.

The major disadvantages to this system are related to the winter conditions experienced
in Canada. Unlike the batch windrows described above, these windrows require
continuous feeding and are difficult if not impossible to operate in the winter. In
addition, if windrow covers are used, they must be removed and replaced every time the
worms are fed, creating extra work for the operator. The advantages of top-feeding
have mainly to do with the greater control the operator has over the worms’
environment: since the food is added on a regular basis, the operator can easily assess
conditions at the same time and modify such things as feeding rate, pH, moisture
content, etc., as required. This tends to result in a higher-efficiency system with greater
worm production and reproduction.

OACC Manual of On-Farm Vermicomposting and Vermiculture Page 20 Harvesting is usually accomplished by removing the top 10-20 cm first, usually with a
front-end loader or tractor outfitted with a bucket (Bogdanov, 1996). This material will
contain most of the worms and it can be used to seed the next windrow. The remaining
material will be mostly vermicompost, with some unprocessed bedding. This can be
used as is or screened, with unfinished material put back into the process. This is
essentially the system used by North America’s largest vermicomposting facility, a 77-
acre operation run by American Resource Recovery in northern California that processes
300 tons of paper wastes per day (VermiCo, 2004).

A Canadian farm wishing to use this system to process manure or other on-farm waste
could consider operating the windows as top-feeding, continuous-flow systems during
the summer months, then covering them with up to half a meter of straw or other
insulating material in late fall and leaving them for the winter. In spring the insulating
cover could be removed and a layer of fresh food placed on top. This will draw the
worms to the surface, where they can be scooped off and used to seed the new
season’s windrows. The material that remains should be well processed and ready to
apply to the fields. 3.2.3 Wedges (continuous flow) The vermicomposting wedge is an interesting variation on the top-fed windrow. An initial
stock of worms in bedding is placed inside a corral-type structure (3-sided) 15 of no more than three feet or one meter in height. The sides of the corral can be concrete, wood, or
even bales of hay or straw. Fresh material is added on a regular feeding schedule
through the open side, usually by bucket loader. The worms follow the fresh food over
time, leaving the processed material behind. When the material has reached the open
end of the corral, the finished material is harvested by removing the back of the corral
and scooping the material out with a loader. A 4 th side is then put in place and the direction is reversed. Using this system, the worms do not need to be separated from the vermicompost and
the process can be continued indefinitely. During the coldest months, a layer of
insulating hay or straw can be placed over the active part of the wedges. The corrals
can be any width at all, the only constraint being access to the interior of the piles for
monitoring and corrective actions, such as adjustment of moisture content or pH level. A
corral width of about 6 feet, with space between adequate for foot travel, would be
ideal. The ideal length will depend on the material being processed, the size of the
worm population, and other factors affecting processing times.

The sides of the corrals can be made of any material at all, although insulating value is a
consideration. Hay or straw bales will gradually break down over time and be consumed
by the worms; as a bale loses its structural integrity, however, it can be added to the
contents of the wedge and replaced with a fresh one.
15 The wedge need not have sides at all, in which case it is simply a windrow system where the operator adds feed to one horizontal face, as applied to the top. However, enclosing the sides
of the wedge provides a number of benefits, including winter insulation and retention of moisture, so the wedge is discussed here as a 3-sided enclosure or corral. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 21
Operating the wedge system over the winter is challenging, though not impossible. The
regular addition of fresh manure to the operating face can create enough heat to
produce a “temperate zone” behind the face within which the worms will continue to
thrive and reproduce. Another option would be to load up the face with fresh manure in
late autumn, cover all of material with a thick layer of straw, and uncover and begin
operations again in the spring. The latter was the approach used in the OACC trials; it
worked very well (see Appendix D). 3.3 Beds or Bins 3.3.1 Top-fed beds (continuous flow) A top-fed bed works like a top-fed windrow. The main difference is that the bed, unlike
a windrow, is contained within four walls and (usually) a floor, and is protected to some
degree from the elements, often within an unheated building such as a barn. The beds
can be built with insulated sides, or bales of straw can be used to insulate them in the
winter. If the bins are fairly large, they are sheltered from the wind and precipitation,
and the feedstock is reasonably high in nitrogen, the only insulation required may be an
insulating “pillow” or layer on top. These can be as simple as bags or bales of straw.

The beds built on the Scott farm (see Figure 6) have walls of mortared cinder block.
They are on a concrete floor inside the chicken coop, which is the lowest level of an old
barn. The area receives some heat from a greenhouse attached to the building, but
winter temperatures are consistently well below freezing. The bins are covered in the
winter with insulating pillows made by stuffing bats of pink fibreglass insulation inside plastic bags. During the first winter of
operation, the top insulation was not added
until well into the winter, when it appeared
possible that the tops of the bins might freeze
over. After the insulation was put on top, the
bins came through a very cold winter quite well,
with only a slight drop-off in efficiency. The
reader should note that these beds were
designed for vermiculture, rather than
vermicomposting. The goal was to raise worms
as feed for organic chickens (see Appendix C).

Harvesting vermicompost can be most easily accomplished by taking advantage of horizontal migration. The beds on the Scott farm
were built end-to-end, with metal screen separating the different beds. To harvest, the
operator simply stops feeding one of the beds for several weeks, allowing the worms
time to finish that material and then migrate to the other beds in search of fresh feed.
The “cured” bed is then emptied and refilled with bedding, after which feeding is
resumed. This is repeated on a regular rotating basis. If the beds are large enough,
they can be emptied with a tractor instead of by hand. Fig 6: Cinder-block worm beds on Scott farm
Worm beds such as the ones described above are similar to the typical beds used by
worm growers in the southern United States. These beds have the advantage of being OACC Manual of On-Farm Vermicomposting and Vermiculture Page 22 more contained than windrows, and thus more controllable in terms of environmental
conditions. The main disadvantage to this system is the extra cost of building and
maintaining the beds, as well as the cost of shelter (e.g., barn floor space). In the US,
where there is a big market for Eisenia as bait worms 16 , the cost is easier to justify. In Canada, the economics will depend to a large degree on the purpose of the activity:
vermiculture for the production of high-protein organic chicken feed, for instance, may
justify this type of system. 3.3.2 Stacked bins (batch or continuous flow) One of the major disadvantages of the bed or bin system is the amount of surface area
required. While this is also true of the windrow and wedge systems, they are outdoors,
where space is not as expensive as it is under cover. Growing worms indoors or even
within an unheated shelter is an expensive proposition if nothing is done to address this
issue.

Stacked bins address the issue of space by adding the vertical dimension to
vermicomposting. The bins must be small enough to be lifted, either by hand or with a
forklift, when they are full of wet material. They can be fed continuously, but this
involves handling them on a regular basis (Beetz, 1999). The more economical route to
take is to use a batch process, where the material is pre-mixed and placed in the bin,
worms are added, and the bin is stacked for a pre-determined length of time and then
emptied. This method is used by a number of professional vermicompost producers in
North America.

In an experiment carried out by the author in Nova Scotia in 2003-04 (GEORG, 2004),
cattle manure was mixed in a 1:2 ratio by volume with shredded cardboard, placed in
stacked bins that were 1.2 m (4 ft) square and either 30 cm (12 in.) or 45 cm (18 in.) in
depth (see Figure 7). Each bin was inoculated
with 2.27 kg (5 lbs) of worms. The bins were
stacked in an unheated building in December
and harvested in June, approximately 6
months later. The bins were constructed of
5/8” particle-board and were stacked together
within an 8’ by 8’ framework of 4’ by 8’ sheets
of particle board covered with rigid foam
insulation rated at R2. The top was covered by
one thickness of standard pink fibreglass
insulation covered on both sides by sheet
plastic. The material did not freeze over the
winter, as the decomposing manure brought
temperatures within the bins into the 30 to Fig. 7: The framework for the stacked bins 16 Eisenia fetida is a small worm and is not generally considered a good bait worm in Canada, where it has to compete with the Canadian night crawler. The latter is a much larger anecic worm (see p. 1)
harvested in huge numbers by worm pickers on golf courses in central Canada. In the southern U.S., where
heat-averse night crawlers have to be imported and kept cool until used, raising their price considerably, the
bait market has been very well exploited by compost-worm growers, who have developed formulae for
“fattening” the worms for bait purposes. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 23 40 o C range for the first month or so 17 and then kept them well above freezing for the balance of the winter.

All of the material was completely processed after six months and the worm populations
had increased by a factor of 3. Some of the bins had contained aged manure (at least
one year), while the others had fresh manure (two weeks). The bins with the fresh
manure experienced a 4-fold increase in worm-biomass increase (a doubling period of 3
months), while the aged manure doubled its worm biomass. The vermicompost in all
bins was mature and rich. It was tested in plant-growth trials with excellent results (see
Section 5).

The main disadvantage of the stacked-bin system is the initial cost of set-up. It requires
an unheated shelter, bins, a way to mix the bedding and feed, and equipment to stack
the bins, such as a forklift. On a smaller scale, of course, this could all be done by hand.
Another disadvantage arises when it comes time to harvest. As with the batch windrow
systems, the worms are mixed in with the product and need to be separated. That
requires either a harvester (see Figure 5) or another step in the process, where the
material is piled so that the worms can migrate into new material (see Section 4). 3.4 Flow-Through Reactors The flow-through concept was developed by Dr. Clive Edwards and colleagues in
England in the 1980s. It has since been adopted and modified by several companies,
including Oregon Soil Corporation of Portland, Oregon, and the Pacific Garden Company,
based in Washington and Pennsylvania. The latter company was started in the last few
years by Dr. Scott Subler, a former colleague of Clive Edwards at Ohio State University.
A variation of this system is also used by Vermitech, an Australian company that has
built three biosolids processing facilities in that country over the past five years (Fox,
2002). The system operates as follows. The worms live in a raised box, usually
rectangular and not more than three meters in width. Material is added to the top, and
product is removed through a grid at the bottom, usually by means of a hydraulically
driven breaker bar. The term “flow-through” refers to the fact that the worms are never
disturbed in their beds – the material goes in the top, flows through the reactor (and the
worms’ guts), and comes out the bottom (E. fetida tends to eat at the surface and drop
castings near the bottom of the bedding). The method for pushing the materials out the
bottom is usually a set of hydraulically powered “breaker bars” that move along the
bottom grate, loosening the material so that it falls through. Clive Edwards has stated
that a “properly managed” flow-through unit of approximately 1000 ft 2 surface area can process 2 to 3 tonnes per day of organic waste (Bogdanov, 1999).

Commercial versions of this system are available, two of the most notable being the
Worm Wigwam ( http://www.wormwigwam.com ) and the Vermi Organic Digester ( http://www.vermitechsystems.com ). They do tend to be expensive, however, and a farmer familiar with basic welding could easily construct one (although the hydraulic
breaker system would need to be purchased, unless it could be adapted from existing
17 The 40 o C temperatures were at the centre of each bin. Because of the cold air outside, there were always areas of cooler temperatures available near the edges of the bins. This allowed the worms to retreat
from the excessively high temperatures that occurred over the first few weeks. If this process were to be
carried out in summer, the C:N ratio might have to be higher to avoid cooking the worms. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 24 farm equipment). The reader should note that although the basic concept is in the
public domain and not patentable, the companies mentioned above may hold patents
(or have them pending) on specific improvements to the system. This should be checked
by anyone planning to build their own unit.

There seems to be little doubt expressed in the literature that the flow-through units are
the most efficient vermicomposting systems available. They probably represent the
future of commercial vermicomposting. The author has had direct experience with one
of these units and can attest to their high potential, when managed properly. However,
the interested reader should probably start with one of the simpler, less expensive
systems before graduating to a flow-through digester. Vermicomposting is basically a
type of farming, rather than an industrial process. It therefore makes sense to master
the basics and to assess the opportunities (see Section 6.2) before making a significant
investment is such specialized equipment. OACC Manual of On-Farm Vermicomposting and Vermiculture Page 25 4 On-Farm Vermiculture 4.1 Vermiculture Systems Vermiculture focuses on the production of worms, rather than vermicompost. As
mentioned earlier, growing worms efficiently requires a somewhat different set of
conditions than vermicomposting. The most basic differences are as follows:
• Population density. Worm growers usually keep their beds at a density between 5 and 10 kg/m 2 (1 to 2 lbs/ft 2 ). This ensures a high reproductive rate. Efficient vermicomposting operations would start at 10 kg/m2 and try for even
higher densities (although windrows and other low-tech systems will have those
high densities only in certain areas, where environmental conditions are closest
to optimum, well-managed flow-through systems would operate at these levels
or higher throughout the bed). • Type of system. Vermiculture operators usually select systems that give them greater control over the environmental conditions. This means beds or stacked
bins as opposed to windrows or wedges. The flow-through reactor could be used
for vermiculture, but is generally used for vermicomposting because of its high
capital cost and its efficiency in producing vermicompost. Worms can be
harvested sustainably from a flow-through system, but doing so will decrease the
vermicomposting efficiency. • Harvesting methods. Vermiculture systems require special techniques for harvesting worms, since the systems usually favoured by vermicomposting
operators (e.g., vertical and horizontal migration into new bedding) only separate
the worms from the finished material. These methods are discussed in Section
4.2 below. 4.2 Methods of Harvesting Worms 4.2.1 General Worm harvesting is usually carried out in order to sell the worms (see Section 6.2.2),
rather than to start new worm beds. Expanding the operation (new beds) can be
accomplished by splitting the beds, that is, removing a portion of the bed to start a new
one and replacing the material with new bedding and feed. When worms are sold,
however, they are usually separated, weighed, and then transported in a relatively
sterile medium, such as peat moss. To accomplish this, the worms must first be
separated from the bedding and vermicompost. There are three basic categories of
methods used by growers to harvest worms: manual, migration, and mechanical
(Bogdanov, 1996). Each of these is described in more detail in the sections that follow. 4.2.2 Manual Methods Manual methods are the ones used by hobbyists and smaller-scale growers, particularly
those who sell worms to the home-vermicomposting or bait market. In essence, manual
harvesting involves hand-sorting, or picking the worms directly from the compost by
hand. This process can be facilitated by taking advantage of the fact that worms avoid
light. If material containing worms is dumped in a pile on a flat surface with a light OACC Manual of On-Farm Vermicomposting and Vermiculture Page 26 above, the worms will quickly dive below the surface. The harvester can then remove a
layer of compost, stopping when worms become visible again. This process is repeated
several times until there is nothing left on the table except a huddled mass of worms
under a thin covering of compost. These worms can then be quickly scooped into a
container, weighed, and prepared for delivery.

There are several minor variations and/or enhancements on this method, such as using
a container instead of a flat surface, or making several piles at once, so that the person
harvesting can move from one to another, returning to the first one in time to remove
the next layer of compost. They are all labour-intensive, however, and only make sense
if the operation is small and the value of the worms is high (see Section 6.2.2 for a
discussion of worm prices and markets). 4.2.3 Self-Harvesting (Migration) Methods These methods, like some of the methods used in vermicomposting, are based on the
worms’ tendency to migrate to new regions, either to find new food or to avoid
undesirable conditions, such as dryness or light. Unlike the manual methods described
above, however, they often make use of simple mechanisms, such as screens or onion
bags.

The screen method is very common and easy to use. A box is constructed with a screen
bottom. The mesh is usually ¼”, although 1/8” can be used as well (Bogdanov, 1996).
There are two different approaches. The downward-migration system is similar to the
manual system, in that the worms are forced downward by strong light. The difference
with the screen system is that the worms go down through the screen into a prepared,
pre-weighed container of moist peat moss. Once the worms have all gone through, the
compost in the box is removed and a new batch of worm-rich compost is put in. The
process is repeated until the box with the peat moss has reached the desired weight.
Like the manual method, this system can be set up in a number of locations at once, so
that the worm harvester can move from one box to the next, with no time wasted
waiting for the worms to migrate.

The upward-migration system is similar, except that the box with the mesh bottom is
placed directly on the worm bed. It has been filled with a few centimeters of damp peat
moss and then sprinkled with a food attractive to worms, such as chicken mash, coffee
grounds, or fresh cattle manure. The box is removed and weighed after visual inspection
indicates that sufficient worms have moved up into the material. This system is used
extensively in Cuba, with the difference that large onion bags are used instead of boxes
(Cracas, 2000). The advantage of this system is that the worm beds are not disturbed.
The main disadvantage is that the harvested worms are in material that contains a fair
amount of unprocessed food, making the material messier and opening up the
possibility of heating inside the package if the worms are shipped. The latter problem
can be avoided by removing any obvious food and allowing a bit of time for the worms
to consume what is left before packaging.
OACC Manual of On-Farm Vermicomposting and Vermiculture Page 27 4.2.4 Mechanical Methods Mechanical harvesters are the quickest and easiest method for separating worms from
vermicompost. The following description is from Bogdanov (1996):
“…the mechanical harvester…is a trommel device, a rotating cylinder about 8-10 feet in length and 2-3 feet in diameter. The cylinder walls are composed of screen material of different mesh sizes. The cylinder is rotated by a small electric motor mounted on one end of the cylinder. The trommel is set a an angle; at the upper end of the rotating trommel worms and their bedding 9including castings) are added. As the cylinder rotates, the castings fall through the screen. The worms ‘ride’ the entire distance of he trommel and pass through the lower end into a wheelbarrow.” t t

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