Vermicompost is said to be the most effective compost available. At Black Coffee Organics we farm with the red wriggler (Eisenia fetida), but a number of other worms species are also good at making vermicompost (as is a species of cockroach, believe it or not). We use red wrigglers because they are surface worms and adapt well to worm compost farming.
A number of approaches to worm farming are evident around the world. Broadly speaking, worm farm design can be divided into 3 categories - continuous horizontal flow, continuous vertical flow and non-continuous. Freedom to Read's "A Beginners Guide to Starting a Worm Farm" has more information on this.
At Black Coffee Organics we have chosen to take a continuous vertical flow approach. As can be seen from the accompanying photograph, we use an old tyre system - stacking tyres one on top of the other as each level fills with compost.
The idea here is that, when the upper level is full and it is time to add a new level, the level below the upper level should be full of compost and almost devoid of worms, since red wrigglers inhabit the surface. The very first level is always a "home" level, filled with coir, where the worms can escape to if something goes wrong biologically in the hive.
Because, in our minds, there is a difference between decomposition and rotting. We define rotting as the decaying process involving what are essentially harmful microses - microbes which you would not want in your worm hive or soil. Decomposition, on the other had, is decay under the influence of good microse, such as those found in effective microbe solutions and probiotics - not very scientific, we know :-). In any event, we prefer to start the decomposition process under the influence of effective microbe and probiotic solutions, rather than simply adding animal and vegetable waste to our worm hives, which may cause problems for the worms.
We are fortunate enough to have access to horse manure, which we collect on a weekly basis. The horses are free-roaming and we scour the veld for piles of horse droppings. Fortunately, horses have this habit of defacating in the same places, i.e. creating a number of mini-middens. These mini-middens are usually on the road.
We add to the slightly aged horse manure 3 x 10ℓ buckets full of waste coffee grounds which we collect from coffee schops in town on a weekly basis (we know who sells the most coffee in town, but we're not telling :-).
While the coffee we drink is acidic, the waste coffee grounds are almost neutral, with a pH of 6.5 to 6.8. Coffee grounds are also an excellent source of nitrates. A further benefit provided by coffee grounds is the fact that red wrigglers require grit in the digestive system to process their food and coffee grounds, along with sand, provide for this. Also added is the vegetable waste from a number of households, which is chopped finely in a food processor before being assed. It is also frozen to help break down cell walls and make for quicker decomposition.
A mixture of Pro-Biome Indigenous Microbe Solution and Pro-Biome Probiotic Solution is sprayed onto the compost heap every morning and the compost heap is aerated as composting is an aerobic process.
After a week the compost, actually pre-compost as the composting process is on-going, is fed to the worms. Approximately 3 cm of pre-compost is added at a time, usually once per week, but as the worm population increases, so does the feeding frequency and most of our hives are now fed twice per week.
We do this pre-composting because it is important that food in the worm hives does not rot. Worms are fussy eaters and rotting, smelly food is definitely not on their menu. Because microbes have been used to induce decay, rotting is unlikely.
In the beginning we added the mixture of horse manure, coffee grounds and vegetable waste directly into the hives and then sprayed with microbes. However, the initial stage of composting generates significant heat - 60 to 70oC or more, and worms become very unhappy if the temperature exceeds 40oC; the consequences are obvious.
At harvest time, worms are removed from the compost (well, as many as possible) and the compost is bagged. Initially we sifted the compost, but have since discovered that vermicompost is a delicate living ecosystem and too much handling disturbs this eco-balance. We now handle the compost as little qs possible. Our compost is also sold moist (as opposed to wet) to maintain the life of our product.
Producing vermicompost is not a quick process, it involves hard and regular work and it is fraught with challenges. But when you get it right it is extremely rewarding.