The sustainable vegetables that thrive on a diet of fish poo...
Who needs soil when you have a fish tank? “Aquaponics” combines growing plants in water, or hydroponics, with fish cultivation, or aquaculture. It’s a symbiotic process that has its roots in Asian farming practices reaching back thousands of years. When used well, aquaponics can increase local food production and make communities more resilient – all without creating pollution or using scarce resources, such as oil.
It begins with fish poo and pee, both of which contain lots of ammonia. Worms that live in rooting substrates break the solids down and then bacteria convert the ammonia into nitrate, which acts as a fertiliser. The plants absorb the nitrate and effectively filter the water for the fish. By which point the fish will once again need the toilet, and so on. It’s a virtuous circle.
The result is high-density food production that works equally well at home or in large industrial warehouses. It’s suitable in urban spaces or on land suffering from drought, pollution or soil depletion that is otherwise difficult to farm. It produces both fish and vegetables, reducing the load on our over-exploited and polluted oceans.
Year-round growing is possible (for indoor systems), and the system is even more water efficient than hydroponics, producing two products using the same water. Fish food is the only major input required, and it’s easier to use bio-controls against pests compared to soil-based agriculture.