Community projects in Harare are not normally associated with organic food production, let alone the export market. Earthworm farming is changing that and its success could become a model for community-based projects nationwide to grow organic produce or green the city. To date several community groups from Harare’s Waterfalls, Hatcliffe, Mabvuku and Tafara suburbs have embraced earthworm farming which has agricultural, financial and environmental benefits.
According to scientist Dr Ephrem Whingiri, the Chief Executive of Zim Earthworm Farms, the organisation resolved to assist these communities after realising that in urban areas huge amounts of organic matter is produced from vegetable and fruit waste, wastewater, aquatic weeds, animal waste from abattoirs, sawdust, and household and industrial waste. “It goes to toilets, dams, rivers and landfills, and in some cases it is incinerated. There is, therefore, a desperate need to restore the ecological balance.”
The huge quantities of organic vegetable waste generated in urban areas has city authorities struggling to manage its disposal and also increases the city’s running costs. It is imperative to find cost effective and profitable ways of disposing of vegetable waste and community involvement is needed. Recent work done by the Environmental Management Agency, through the University of Zimbabwe, established that Zimbabwe produces about one million tons of biodegradable organic waste annually.
“Earthworm farming involves recycling of organic food waste generated during the harvesting, processing and packing of foods and other waste including chicken litter,” he explains. “The worms recycle the organic waste via a process of aerobic composting or vermicasting. Vermiculture produces vermicast (vermicompost), earthworm faeces, and worm tea. All these are rich in nutrients for plants. Growers using this organic fertiliser are tapping into the growing and lucrative overseas market for organic goods and sending carrots, lettuce, tomatoes, beetroot and cucumbers to South Africa, Mauritius and even into Europe. Dried earthworms are high in protein and can be processed into a good animal feed, which will reduce imports for the animal feed industry.
Dr Whingwiri has also suggested other uses for earthworms, “They have the ability to remove all the harmful elements in water. The problems of water-borne diseases such as cholera, dysentery and typhoid can be solved. In fact earthworms have the ability to remove some of the micro–organisms which a standard sewage system cannot remove,” he said. He goes on to say that the water flush toilet, in which worms feed on human waste, could be used as a sewage management method in Harare. When earthworms placed in filter beds feed on the human waste from the flush toilet, the water is purified and can be re-used for gardening. This method would reduce costs for the City of Harare and help solve the water woes that the municipality is currently grappling with.
According to the scientist, worm farms can play an important role in combating climate change as decaying agricultural waste is the second-leading cause of climate change. When organic refuse is land-filled, it generates methane gas due to anaerobic conditions. Methane gas is a greenhouse gas that contributes to global warming.
“The recycling of organic refuse through aerobic composting is an excellent method to prevent the production of greenhouse gas emissions,” he explains.