Most crops in Uganda are grown on soil. However with declining fertility, Uganda being a country that relies heavily on agriculture will most likely find itself in problems when the land can no longer produce the required food.
But there is hope with new techniques of faming that rely on a symbiotic relationship between crops and marine life. The technique is an integration of hydroponics and aquaculture, in a sustainable method of food production.
This process entails pumping of nutrient rich effluents from fish tanks to hydroponic plants thus providing the needed plant nutrients. The plants which are actually planted in rocks instead of soils get their nourishment from the effluents from the fish tank. In the process of feeding the plants act a bio filters for the water removing ammonia, nitrates and phosphates laving the water cleansed. The water is then pumped back into the fish pond.
A lady in one of Kampala’s rocky patches has capitalized on it and is making it big. Maria Mabira now breeds fish and cultivates vegetables on a small otherwise agriculturally unproductive piece of land.
The practice taught Mabira one important lesson and that is crops just need water and certain nutrients to grow and not soil.
HOW ARE THE PLANTS AND FISH CULTIVATED AND GROWN?
While fish are placed in tanks where they grow, troughs and made for plants and are lined with polythene sheets to trap water. The troughs are then filled with pebbles and water with effluents is released into them. After the plants extract the nutrients (effluents) they and the stones filter the water before it is pumped back to the fish tank. And the cycle continues. Such technology can even be used on rooftops. The technology produces 100% organic products. It also uses less water than other agricultural technologies.
RETURN ON INVESTMENT
Under a greenhouse, this technology requires sh3.2m. However, each month, a farmer who grows high-value vegetables such as lettuce can earn sh1.8m from the vegetables. After six months, fish such as cat and tilapia can also fetch as much as sh900,000.
The vegetables help the farmers earn money to buy feeds for the fish.