Vermicomposting coffee waste into nutrient-rich fertiliser

Relief is in the offing for coffee factories in Kenya, which have been struggling with mounds of coffee wastes in their compound.

This is following the launch of a project by the International Centre of Insect Physiology and Ecology (Icipe), which converts the black smelly pulp into rich fertilisers.

Vermicomposting

This vermicomposting procedure uses earthworms to breakdown the coffee wastes after the layers of skin, pulp, mucilage and parchment that surrounds the beans, have been removed.

The major residues are coffee husks and pulp, which add to 50 per cent of the total coffee weight.

These residues contain toxic substances that are low in pH, high in organic load, caffeine, tannins, polyphenols and inorganic nutrients.

In some places, coffee processing is done around river banks, and the effluent is pumped directly into the water. This impacts on the biodiversity, people’s health and livestock ecosystem, negatively.

“Not all earthworms can vermicompost, only a few have such the capacity to do this. Our studies have demonstrated that three earthworm species: Eisenia fetida and E. andrie and Dendrobanae veneta, can manage various organic wastes,” said Prof Gezahegn Degefe of Debre Berhan University, Ethiopia, where the pilot project is taking place.

According to the professor, the project has established the substrates that provide the most efficient growth and re-productivity in earthworms. This is important in rearing cocoons under lab conditions for sustainable vermicomposting.

How it is done

Vermicomposting consists of a light-proof unit (because worms do not like light) and bedding trays.

Coffee waste is collected from villages, spread on the bedding trays and mixed with soil in recommended rations. Worms are then introduced into the mixture.

According to scientists, regular watering and turning will make the organic fertiliser ready within two months.

The water aids the disintegration process by creating a suitable medium for microbial action.

Benefits

“Farmers have reported that the solid biofertiliser keeps the soil fertile and increases the water holding capacity. It also has a more superior performance compared to synthetic fertilisers and traditional compost,” says Prof Degefe.

“The liquid fertiliser is sprayed on the soil and leaves of plants. It leaves a very deep green, which is a sign of health and strength. It also improves the performance of the biomass of coffee and other plants.”

Cost of the fertilisers

The fertiliser is sold in solid and liquid form.

It is packaged in 100 kilogramme bags and sells at Ksh850.  Five litres of the liquid fertiliser go for Ksh145.

Known as the BioInnovate Africa Programme, the project is supported by the Swedish International Development Cooperation Agency and managed by Icipe.