Fish, worms and bio-waste - three technologies to make urban farms bloom

Fish: Food for people and plants

One of the technologies that are fit for urban farmers is an aquaponics system. Aquaponics – or fish farming – has been booming in Kampala in recent years. Globally, it is the fastest growing form of farming with an increase in the number of fish farmers with 10% each year. It is in high demand because the initial investment is affordable, and a farmer gets a high return on investment. In Kampala, challenges of farmland scarcity and water pollution are overcome by optimizing the aquaponics system: intensification by the use of tanks, use of rainwater and water purification and recirculation systems.

In short, an aquaponics system means the simultaneous farming of fish and vegetables, providing both food for people and plants. The fish are bred in a pond or tank that is linked up to a filtering system. Fish excreta are channeled to the filtering system where vegetables such as cabbage or lettuce are grown. While people can eat the fish, the plants use the nutrients from the fish excreta to grow and at the same time purify the water that can flow back to the tank. This economises water use and avoids environmental pollution by wastewater.

The power of the worms: From waste to all-natural fertiliser

Worms are the central feature of yet another urban farming technology: Vermicomposting. Vermicomposting is a method of making compost with the use of earthworms, which generally live in soil, eat biomass and excrete it. This worm-made vermicompost is one of the highest-grade and most nutrient-rich natural fertilisers in the world. It enriches the soil and strengthens plants to encourage growth as well as yield of the plants.

A vermicomposting system addresses two very important challenges in the urban setting: It takes care of organic waste, and it produces an enriched soil that is extremely helpful for plant growth. A worm farm can recycle one third of household waste. This recycling process helps the environment by keeping tons of waste out of landfills and turning it into vermicompost instead. Further addressing environmental challenges, the worm castings produced by vermicomposting add important nutrients back into the soil thereby improving soil quality and productivity. Vermicompost also contributes to food safety as it is an all-natural, organic fertilizer that eliminates the need for harmful chemicals in the production of fresh fruits and vegetables. Worm composting can even be turned into a business provided that one has the appropriate structures. Schools, institutions, prisons and other facilities can set up vermicomposting bins right on their site to recycle food waste into a valuable product.

In summary, vermicomposting is an activity that combines social, environmental, and economic sustainability. Providing benefits to people and planet, as well as contributing to profit, urban farmers have plenty of incentives to set up a vermicomposting system.

From dung to clean energy

If you have been around cows and pigs for a just a bit, it is not hard to imagine the big challenge that urban livestock farmers face: Disposing figurative mountains of livestock manure in a socially acceptable, economically affordable, and environmentally sustainable manner. A biogas system offers not only a solution to this challenge, but also produces clean energy as an extra benefit.

A biogas system can consume any biodegradable material to convert it into biogas and bio-slurry. This recycling process has plenty of benefits:

• Clean energy generation: Biogas is a clean fuel that provides an alternative to dirty and unsustainable fuels like firewood and charcoal.
• Better sanitation: By removing manure (biowaste), household surroundings are freed of waste that would have turned into a breeding ground of vermin and disease-causing organisms.
• Improved health conditions: Biogas can be used for cooking and therefore replaces burning firewood and charcoal that causes a lot of indoor pollution leading to respiratory and eye infections.
• Sustainable urban agriculture: Bio-slurry, a by-product of a biogas system, is rich in plant nutrients that are ready to use in urban farms, reducing the need for synthetic fertilizers and improving the soil for better crop productivity and production. Bio-slurry is also an excellent animal feed supplement for pigs, local chicken, ducks, and fish among other animals.
• Environmental protection: Biogas use reduces dependence on trees for energy by offering an alternative to firewood and charcoal. This helps to protect the environment. Also, through improved soil structure and water retention capacity, bio-slurry enhances the farmer’s resilience to climate change.

While setting up a biogas system might seem challenging at first, urban livestock farmers highly appreciate the advantages, especially the autonomous access to affordable clean cooking and lighting, improved sanitation, and resilience to the effects of climate change.

In five divisions of Kampala, KCCA and Rikolto have trained model urban farmers that demonstrate these three technologies to their communities and fellow urban farmers. Visitors to the model farms can see the benefits with their own eyes and get more information about how to set up these technologies at their own home.