By Silke Bollmohr
One of the marks that distinguish a good organic farmer is the ability to acknowledge that not all small organisms on the farm are pests that, in fact, some are precious and highly beneficial. Earthworms fall into this category of beneficial organisms.
There are over 1,000 species of earthworms in the world, with different physical appearances and colours. Red earthworms are most commonly used in vermicomposting as they can feed and convert organic matter into compost faster than other earth-worms. They also adapt to new environment much faster. They can eat as much as their own body weight each day, and provide solid and liquid nutrient-dense waste, which nourishes plants. As earthworms eat and digest plant material, they mix organic and mineral soil particles. The organic matter is enriched and then passed out of the worm’s body in the form of casts, which are the richest and finest quality of humus. In this way, they help build and maintain the soil structure. Their casts (waste) contain nitrogen, phosphorus, potassium, magnesium and calcium.
Habitats that earthworms like
Humus is food for worms. Soils rich in humus will naturally attract earthworms. Therefore, to attract them, ensure that your farm is rich in humus.
Worms dislike too much sun and mulch prevents their direct exposure to the sun’s powerful rays, which enables them to be comfortable and to focus on breaking down the humus. Therefore, mulch your soil.
Benefits of earthworms
Earthworms like burrowing themselves beneath the soil, leaving little channels that loosen and improve soil aeration and drainage. Soils with poor aeration and water drainage suffocate the roots of plants resulting in poor growth.
Their castings improve soil structure by cementing soils into aggregates (soil particles that are bound together) that retain moisture for longer, without breaking apart.
Soils with earthworms are better yielding than those without and farmers should consider rearing worms in addition to having them on the farm in the soil as they provide worm juice, worm castings, and food for chicken and fish. You can also sell the worms to other farmers.
How to rear earthworms
- A plastic open drum or a wooden box measuring ca. 60 cm deep, 180 cm long and 120 cm wide
- Topsoil with some worms
- Fresh dung or droppings from cattle, sheep, goats, pigs or rabbits
- Dry materials, e.g. grass
- A suitable cover, e.g. a sisal sack
- Some water
- Step 1: Mix all the top soil, dung/droppings, grass and some water thoroughly in the open drum or box. Do not use too much water to avoid making the growth medium too wet and therefore unsuitable for worm rearing
- Step 2: Cover the mixture of topsoil, dung etc, with a sisal sack and place the drum or box in the shade. Make sure that moist conditions predominate in the growth medium all the time
- Step 3: Harvesting. In two weeks, the worms have grown and multiplied. The big worms can be harvested by sieving them with a wire mesh. Place them in a separate container for use according to the desired purpose. They can be used to make vermicompost, or they can be fed to chickens and fish.
How to make vermicompost
Vermicomposting is the use of earthworms to transform organic materials into rich, organic fertilisers.
The production of vermicompost requires from three to six months.
1. Prepare a bed with a concrete, wood or plastic sheet bottom and construct walls 20 to 30 cm in height using wood, logs or stone. On one end put a ½ inch drainage pipe, that allows for collection of juice. Place a wooden board across the bottom and line with chicken wire for better handling and aeration.
2. Place a 10 to 15 cm layer of coarse organic materials such as banana waste, maize stover, coffee husks and other crop residues on top of the chicken wire. The material must not contain poultry manure as this is harmful to worms.
3. Place a 5 to 10 cm layer of manure on top of the coarse material. Cattle, pig, sheep or goat manure are suitable. Green manure, such as tree leaves or grass cuttings may be substituted. Add organic matter such as potato peelings, vegetable remains, grasses, crop and any material that can break down easily like fruit and vegetable peels to ensure the earthworms have enough organic matter to feed on.
Sprinkle some water thoroughly in the open drum or box. Do not use too much water to avoid making the growth medium too wet and therefore unsuitable for worm rearing. Sufficient water should be applied so that no pockets of dried material remain. Wet materials such as banana trash and fresh manure need little watering while dried materials may require as much as 30 liters of water per m2 of bed.
4. Release the earthworms into the moist bed. Avoid handling individual worms, rather place small handfuls of material rich in earthworms (clusters) into ‘holes’ spaced about 0.5 m apart.
5. Cover the bed with banana leaves or dark polythene plastic. Apply additional organic wastes periodically. Vermicompost is ready after three to six months.
Note: Worms love uncooked kitchen scraps except for onions, chilies, citrus peels, dairy, fatty foods, meat, and cooked foods.