The Food and Agriculture Organization of the United Nations (FAO), estimates that around 800 million people worldwide practice urban agriculture. FAO believes that urban agriculture provides fresh food, generates employment, recycles urban wastes, creates greenbelts, and strengthens resilience to climate change.
Resurgent interest in urban farming in Kenya, whether it is for the sheer joy of enjoying fresh farm produce, or earning an extra income has helped to complement food supply in Nairobi. In Kawangware informal settlement within Nairobi, Mr. James Njuguna has taken a step in ensuring that he supplies some community members with fresh produce through aquaponics agriculture.
The inventive form of integrated agriculture system that combines hydroponics (Soil-less growing of plants) and aquaculture (fish farming) is gaining popularity due to the believe that It can ensure agricultural sustainability.
Mr. Njuguna started farming 13 years ago. However, reduced agricultural land prompted him to think of alternative ways of using small urban space for farming. Through a friend, he learned about aquaponics and its economic benefits.
He learned that farmers are able to receive more produce through aquaponics compared to conventional farming methods. Vegetables also grow significantly faster and at a higher density. In addition, there is no weeding, soil pest or pathogens.
The system does not rely on weather therefore a farmer can grow crops throughout the year and it conserves water through recirculation for use by fish and growing crops in a symbiotic set up. In addition, the farmer does not incur fertilizer cost since it is a self-sufficient system.
Through technical support from Hydroponics Kenya co Ltd, Mr. Njuguna has constructed a greenhouse measuring 18 by 12 metres. Inside the greenhouse is a fishpond and six troughs filled with porous gravel as a growing medium instead of soil. Each trough has three rows each containing 22 plants while the fishpond has 300 fingerlings. The troughs contains tomatoes, spinach, and black nightshade.
The water system in the fishpond and the crop troughs with gravel are connected by PVC pipes to a water pump that is used for water recirculation. The system works by pumping water from the fishpond to the crops and then back to the fishpond. Clean and oxidized water then returns to the fishpond through an outlet after filtration through the crops tank through porous gravel.
“The food here is organic as we are not using chemical fertilizer. The fish in the pond excrete in the water thus producing nitrate fertilizer that plant roots use as nutrients. A natural microbial process keeps both the fish and plants healthy,” said Mr. Njuguna.
He said that initially he was skeptical about the technology and even wondered how crops could survive in gravel. He had to travel to Mai Mahiu for the gravel. He said that nothing in the farm goes to waste as they reuse everything.
“Most of my neighbours are still skeptical about the farming system. They are waiting for me to harvest the fish and the vegetables in order to also embrace the farming technology for the future,” said Mr. Njuguna.
He also has a vertical hydroponic farm where he has grown spinach and kales. Each tower can accommodate 18 plants. A pump draws nutrient rich water from the tank to the top of the vertical column.
Although he has received support from Hydroponics Kenya co Ltd, he noted that installing the system would be costly for most smallholder farmers. He is planning to adopt drip irrigation and replace his small tank with a 10,000-litre capacity raised tank to ensure that water flows through gravity.
He noted that although the system requires less management compared with other farming techniques, it is imperative to monitor the quality of water as contamination can lead to death of fish.
Space is no longer a challenge for him as he has realized that the closed circuit aquaponics is the best way of ensuring agricultural sustainability for urban farmers. He believes that in a few years, he would not only be enjoying better returns but he will be able to scale up his farming enterprises.