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Recipe suggestion or modern agriculture?
Lamb's lettuce on St. Gallen rosé perch? Berlin perch with spinach? With descriptions like these, these dishes certainly sound interesting. And not only that, they might also be based on tomatofish.
There is a place in the Swiss town of Bad Ragaz where lettuce is cultivated, not on fields, but on a rooftop. Moreover, this lettuce - in winter generally lamb's lettuce – is not grown on soil, but in water that comes from a fish farm located beneath the roof greenhouse.
In Berlin, the same principle is applied to the joint cultivation of components that are typically served together. For example tilapia with tomato, zucchini or spinach. The products cultivated here in Schöneberg are then supplied to the surrounding region. And naturally, this urban farm also has its own farm shop.
Aquaponics is a method of combining agriculture with aquaculture in a joint circulatory system. The term is a hybrid of aquaculture and hydroponics (the cultivation of plants in water instead of soil).
Just as manure accumulating in traditional agriculture is used as fertiliser on the fields, modern fish farmers use water from closed fish tanks as fertiliser for crop cultivation. However, unlike traditional agriculture, it also has the advantage that once the plants have taken their nutrients from the water, it can be reused as fresh water for fish. Not a milligram of fertiliser or a drop of water can make its way unused and uncontrolled into the environment. Even the exhaust air from aquaculture, which is rich in CO2, is fed into the greenhouse, where it is used by the plants as additional fertiliser
Approaching environmentally neutral agriculture
To maintain the cycle, it is only necessary to add water to replace the volume that is lost to evaporation or absorbed by the plants; this is between one and three percent of the total water volume per day. In comparison, in conventional fish farming, it is necessary to replace 10-20 percent of the water per day due to the 'natural fertilisation' of the water from fish excretions. In this case, the useful but unused fertiliser turns into a disposal problem.
The system that forms the basis of these sample projects was devised by Werner Kloas, professor at the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB) in Berlin. The so-called 'tomatofish' is his invention. The aim is to devise a sustainable, resource-friendly and virtually emission-free form of agriculture. For more information on tomatofish, please visit: www.tomatenfisch.igb-berlin.de