See also the “Organic farming” and “Compost and organic fertiliser” chapters
Nobody really knows how many worm species there are (estimates range from 4 500 to 6 000!) but in agriculture and gardening three distinct genera have been studied and described. These worms are distinguished by their habitat in or on the soil. These genera do not interbreed and will not normally be found in each other’s habitat. The three genera are:
- Worms that are found on the surface under damp, decaying organic matter. These are termed epigeic with Eisinia fetida and sub species andreii being most popular amongst vermiculturists in South Africa. These introduced worms are typically not found in ordinary South African soils which are too dry and lack the moist humus environment which they need to survive. Controlled organic waste environments are, however, ideal.
- Worms (termed anecic) that are found from the surface of the soil to a depth of roughly one metre. These worms forage for their food by coming to the surface and dragging damp decaying organic matter down into their burrows. These worms, some indigenous and some introduced, are extremely beneficial as they ‘churn’ the soil and allow good water and air penetration. The more of these species in the soil the better the soil. Lumbricus terrestris is very common in South Africa.
- A third type of worm (termed endogeic) can be found very deep in the soil and very seldom comes to the surface. This type is the only one of the three that actually eats soil as part of its diet. This species plays a small part in the total soil environment.
As soon as any living thing dies – whether it be animal or vegetable – a host of saprophytic micro-organisms including such as bacteria, fungi, moulds, nematodes, actinomycetes, small arthropods begin to devour it. Earthworms then graze on the micro-organisms as feedstock. Some of the decaying matter is also ingested but the main food is the micro-organisms. Worms digest these and the nutrients they have absorbed. Microbial activity increases in the worm’s gut system and the excreted worm faeces are also full of plant nutrients and micro-organisms which not only fertilise the soil, but increase its vitality and ecosystem functioning through the introduction of micro fauna. This results in a far more sustainable growing environment than one which relies on seasonal additions of inorganic fertilisers with their various combinations of carbon, nitrogen and phosphate.
In vermiculture, Eiesenia fetida or similar composting worms like Eudrilus eugeniae worms are kept in captivity and fed decaying organic material. The worm faeces (or “castings”) are collected and used as compost. Many different types of enclosure can be found – ranging from a small box for a household to extremely large concrete pens for large-scale farming. Decaying organic material can be literally anything that was once alive but is now dead: all vegetable matter, paper and cardboard, untreated sawdust, food leftovers and animal manures (with the possible exception of cat litter that can contain pathogens – organisms that can be infectious), rice and pastas etc. Not all of these decay at the same rate or have the same chemical composition and it is best to build up a healthy population of several thousand worms with low acid, cellulose and pathogen feedstock before venturing into more ambitious projects.
When vermicompost is spread on the soil surface, the millions of micro-organisms present become food for any anecic worms in the vicinity. With a plentiful food supply, the anecic worms proliferate and help to keep the soil friable and productive. The life and death activities of the micro-organisms in the soil release continuous plant nutrients and fix elements like nitrogen from the atmosphere.
Both solid composts and compost “teas” can be produced by vermiculture.
Soils treated with vermicompost can contain 5 times more nitrates (i.e. immediately-available nitrogen), 7 times more phosphorus, 11 times more potassium, 2.5 times more magnesium and twice as much calcium as soils non-treated soils.
Source: Ronald Thomson. Patrick Dowling gave the piece considerable thought and contributed suggestions too.
2. Local business environment
The use of earthworms to improve farming practices, to assist farmers who wish to produce organically or to reduce fertiliser costs, has become established in many parts of the world. Australia in the developed world and India in the developing world are prime examples.
As mentioned earlier, in nature the earthworm converts the wastes of nature into food, growth stimulants and microbes all beneficial to plant growth and survival. We may take advantage of this process by concentrating the waste and the earthworms, and then by applying the resultant products directly to specific areas or plants.
- Wasted Waste. Every day tons of organic waste goes to landfill sites all over the continent. This organic matter, often at source, could be converted with the help of the humble earthworm into plant food.
- Farm Waste. Most farmers have some form of organic material that goes to waste, cattle, horse, pig manure, reject vegetables just to mention a few. All are suitable for conversion.
- Process. The waste should be trenched directly into the soil and layered with other specific waste material and worms then introduced. Planting can take place almost immediately and the soil remains in good shape for some time depending on the depth and quantity of organic material used.
Alternatively a Wormery Unit could be established in which earthworms are fed organic waste and the resultant liquid and casts harvested and applied directly to crops. Neither method is expensive.
Once established, these simple methodologies aid food production and expenses are offset by savings on fertiliser, transport and landfill costs. And just as important – this would result in regenerating depleted soils, thus working towards restoring a healthy environment. There is a challenge to farmers to recycle their wastes to reduce fertiliser costs and reduce methane emission.
Source: Don Blacklaw. Find details at www.wizzardworms.co.za.
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