5 Vermiculture Essentials to bear in mind

Introduction to Vermiculture

The rearing of worms for the purpose of making Vermicompost is called Vermiculture. Vermicomposting is the process by which worms are used to convert organic materials (usually wastes) into a humus-like material known as vermicompost. Often these two terms are used interchangeably, but in reality different regimens are advised.

Vermicast is the end-product of the breakdown of organic matter by earthworms. These castings have been shown to contain reduced levels of contaminants and a higher saturation of nutrients than the organic materials before vermicomposting.
Vermicomposting has gained popularity in both industrial and domestic settings because, as compared with conventional composting, it provides a way to treat organic wastes more quickly.

There are literally hundreds of different types of worms, one count as many as 1800 [Edwards & Lofty, 1972], and are classified in 3 classes:

• 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. E.g., Night Crawlers
• 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. E.g., Typical earthworm
• 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. E.g., Red Wiggler

The earthworm species (or composting worms) most often used are red wigglers (Eisenia fetida). Red wigglers are recommended by most vermicomposting experts, as they have some of the best appetites, breed very quickly and most importantly are surface dwelling. This extremely tough and adaptable worm is indigenous to most parts of the world and can often be found in piles of manure that have been left to age for more than a few months.

South Africa has another record in the longest earthworm, Microchaetus Rappi, in 1967 one was literally found crossing the road between Alice and King William’s Town. This monster measured 6.7 m (21 ft) in length, when naturally extended, and 20 mm (0.8 in) in diameter.

The 5 Essentials for Vermiculture

Without further ado, Compost worms need five basic things:

1. A hospitable living environment, usually called “bedding”, with a low C:N ratio
2. A food source
3. Adequate moisture (greater than 50% water moisture content by weight)
4. Adequate aeration
5. Protection from temperature extremes – typically keep in the 0-30°C range.

Small-scale or home Vermicompost

The simplest home composter is made of old 20L buckets, such as cleaned paint buckets, to start your vermiculture endeavors. These can be stacked inside each other to make a worm tower. Keep the bottom bucket intact and for all the other buckets drill holes in the bottom. For worm bedding use cut up newspaper and to this you can add your kitchen scraps. Then when the bucket is 1/4 full you place your next bucket and line with newspaper as bedding. Keep one lid on the topmost bucket – don’t seal it, just to keep out the rain and unwanted fauna and flora.

The worms will decompose the contents of bucket and naturally work their way up through the holes to the next bucket.

Typical earthworms will bury themselves down, while Red Wigglers will raise to surface [Epigeic]. This makes feeding the red wigglers from the top easy and can make towers consisting of buckets – or storage boxes.

Use newspaper as bedding and can be fed kitchen scraps:

• All fruits and vegetables (including citrus, in limited quantities)
• Vegetable and fruit peels and ends
• Coffee grounds and filters
• Tea bags (even those with high tannin levels)
• Grains such as bread, cracker and cereal (including moldy and stale)
• Eggshells (rinsed off)
• Leaves and grass clippings (not sprayed with pesticides)
• Newspapers (most inks used in newspapers are not toxic)
• Paper toweling (which has not been used with cleaners or chemicals)

The eggshells are best left to dry and then crushed up and added, they act as grit and also being mostly Calcium Carbonate will act as a pH stabilizer and neutralize the acids that the decomposing material forms [from lactic acid producing bacteria among others].

The main disadvantage of these systems is their small size – for the buckets the usable volume is only 3-4 liters. Very difficult to control and often overfed, this leads to all kinds of nasties and the worms may even die out. Takes a little bit of practice to get right, basically if it smells – stop. Also try to aid the worms by chopping up/liquidizing the scraps before feeding. Worms don’t have teeth. Very important to add grit, either by adding couple teaspoons sand or crushed eggshells, like birds the worms process the food in their gut with the aid of grit.

Flow-through composter for Vermicompost

A flow through composter is advised and can handle a wide load regime. Easy to make and operate. The principle of the flow-through is successful mostly due to the Red Wigglers that are surface dwelling. Any box can be used – for an urban setup would suggest a 47Liter Rough tote. 5 mm Holes drilled 25 mm apart [ubiquitous inch] and use polypropylene 3-4 mm string to make a ‘ladder’ form down length of container.

Container can have legs attached – or just stacked on bricks. As need access to bottom to scrape out the vermicompost later.

For the newly constructed box you first put down a layer of carboard to contain the bedding. Then you put in 3-4 inches of bedding. Buffered Coco Coir is a good option, cardboard or paper strips.

Optimal dept of the bedding layes is 25-35cm.

The first three months leave the composter alone, you can add your kitchen scraps – but don’t take out the bottom yet. For Red Wigglers they will typically be feeding in the top 5-10 cm and breeding/laying worm castings in the 30 cm below that. Over the 3 months slowly fill to the 40-50cm mark.

Then after three months the cardboard at bottom should also be soft and maybe even partly decomposed already and you can start harvesting. Of course, this is highly subjective as my first worm box harvested after about month and half. But this because my initial layer was dumped out of my worm bucket towers, and frankly yearning to get the Big Blue Boy bin active pictured above.

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.

Harvesting is simply done by pulling a rake between the polypropylene ladder rungs on bottom, a black rubbish bag on ground can catch the vermicompost or if using a tote, you can use the lid. This first ‘harvest’ would though go back on top of worm box as most probably will not be fully decomposed yet. But from now on you can rake and harvest out an inch [25mm] for every inch of food/bedding added to top. Keep the level 30-50 cm from bottom and in this way the flow-through is self-sustaining and quite easy to use.

3 Conditions to increase worm populations

Epigeic worms such as Red Wigglers do reproduce very quickly, compost worm populations can be expected to double every 60 to 90 days, if the following conditions are met:

• Adequate food (must be continuous supply of nutritious food, such as those listed above);
• Well aerated bedding with moisture content between 70 and 90%;
• Temperatures maintained between 15 and 30°C

Starting with a population density less than 2.5 kg/m2 this will delay the onset of rapid reproduction and, at very low densities, may even stop it completely, especially if not ideal conditions. It seems that worms need a certain density in order to have a reasonable chance of running into each other and reproducing frequently. If you just received a small batch of worms, it may be better and quicker to multiply their numbers first in a worm tower as described above – before starting a flow-through bin for vermiculture.

On the other hand, densities higher than 5 kg/m² 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/m² (Edwards, 1999), the most common densities for vermicomposting is between 5 and 10 kg/m². A common practice is to ‘split’ the beds after 2 months to maintain densities at optimal and increase Vermicomposting acreage.

One way to boost the worm population is to bury your feeding scraps in a ball just below the surface. In this way making social fetes for worms to meet, and also if too high in nutrition these balls will heat up with thermophilic bacteria decompositions, and worms can escape to the cooler bedding surrounds.

So, 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 20 cm of bedding only – no feed), you can add fairly high quantities of nitrogen-rich feed to the overall mix.

The Value of Vermicompost

There is a lot of conjecture on ‘black gold’ on the internet and sales hype to be honest. So will just mention some advantages, backed by literature:

• Level of plant-available nutrients. Atiyeh et al. (2000) found that compost was higher in ammonium, while vermicompost tended to be higher in nitrates, which is the more plant-available form of nitrogen. This is backed by several others: NSAC by Hammermeister et al. (2004), Short et al., (1999); Saradha, (1997), Sudha and Kapoor, (2000).
  The NSAC study also showed that the supply rate of several nutrients, including P, K, S and Mg, were increased by Vermicomposting as compared with conventional composting.
• Level of beneficial microorganisms. The literature has less information on this subject than on nutrient availability, yet it is widely believed that vermicompost greatly exceeds conventional compost with respect to levels of beneficial microbial activity. Much of the work on this subject has been done at Ohio State University, led by Dr. Clive Edwards (Subler et al., 1998).
• Ability to stimulate plant growth. This is the area in which the most interesting and exciting results have been obtained. Many researchers have found that vermicompost stimulates further plant growth even when the plants are already receiving optimal nutrition (ie Hydroponic Systems). Atiyeh at al (2002).
• Ability to suppress disease. There has been considerable anecdotal evidence in recent years regarding the ability of Vermicompost to protect plants against various diseases. The theory behind this claim is that the high levels of beneficial microorganisms in vermicompost protect plants by out-competing pathogens for available resources (starving them, so to speak), while also blocking their access to plant roots by occupying all the available sites. From “Soil Ecology” by Dr. Elaine Ingham of Corvallis, Oregon.
  Edwards and Arancon (2004) maybe made the biggest insight on vermicomposts, on attacks by Pythium on cucumbers, Rhizoctonia on radishes in the greenhouse, and by Verticillium on strawberries and Phomopsis and Sphaerotheca fulginae on grapes in the field. The Vermicomposts significantly reduced and suppressed the incidences of diseases. But the pathogen suppression disappeared when the vermicompost was sterilized, indicating that the mechanism involved was microbial antagonism.
• Ability to repel pests. This is a new anecdotal theory, so to be taken with a pinch of salt. In recent research, Edwards and Arancon (2004) report statistically significant decreases in arthropod (aphid, mealy bug, spider mite) populations, and subsequent reductions in plant damage, in tomato, pepper, and cabbage trials with 20% and 40% vermicompost additions to Metro Mix 360 (the control).
  Much more research is required, however, before vermicompost can be considered as an alternative to pesticides or alternative, non-toxic methods of pest control.
• High compost potency. In Argentina, farmers who use vermicompost consider it to be seven times richer than compost, so that only one seventh of the quantity is required (Pajon, no date). Growers in Australia and India report similar findings (Vermitech, 2004; Bogdanov, 2004).

“These investigations have demonstrated consistently that vermicomposted organic wastes have beneficial effects on plant growth independent of nutritional transformations and availability. Whether they are used as soil additives or as components of horticultural soil less media, vermicomposts have consistently improved seed germination, enhanced seedling growth and development, and increased plant productivity much more than would be possible from the mere conversion of mineral nutrients into more plant-available forms.”

”…there seems a strong possibility that plant growth regulators which are relatively transient may become adsorbed on to humates and act in conjunction with them to influence plant growth”

Atiyeh at al (2002)

Vermiculture and Mushrooms

It was during in-house experiments with SMS [Spent Mushroom Substrate] in hydroponics, trying to do Organic Hydroponics, that noticed the worms loved SMS. Although the Dutch Buckets were not a success that hoped for in that the media, consisting of buffered Coco Coir with 20% [v/v] Vermiculite [aka CVG substrate] added to 30 %[v/v] SMS, would often degrade within 1-2 months leaving a mass of worms. At about this time also noted that the SMS added to the growing mushroom heap often when broken up to make the hydroponic media was a worm ball inside! Guess logical in hindsight as proven that Oyster Mushrooms increase the nitrogen content of the substrate.