In The Unterwiehre In Freiburg, Lettuce Grows Almost Under Laboratory Conditions
April 24, 2020
David Rösch grows lettuce. However, not in the soil, but in plastic. Plants like that of his P 3 project could in the future contribute to the food supply of the growing world population.
Salad grows in Oltmannsstrasse. Surrounded by solar companies, insurance companies, and moving companies, 800 salads flourish there, as if they were rooted in juicy South Baden fields. They are not in the ground at all, but in thin plates made of Styrodur plastic, the roots ultimately hang in the air - and yet the lettuce thrives wonderfully in the lower part of the body. How does it work? David Rösch knows that, who sees his initiative primarily as an educational project.
Hydroponics plants could be a solution for feeding the growing world population
David Rösch is not a gardener, but still has a lot to do with nature. He studied forestry and the environment at the University of Freiburg. In the meantime, he was dealing with refugees - and decided to make this his profession. In 2018 he founded his own company: P 3, a workshop in which refugees are trained as carpenters or prepared for an apprenticeship. On the one hand, P 3 produces furniture on request, from stools to fitted kitchens, and on the other hand attachments for cargo bikes as mobile sales and information stands. Then managing director Rösch came up with the idea of the salads a year ago. More specifically: for a hydroponic system (derived from the Greek words for "water" and "wages of work").
The 31-year-old has long thought about how to feed a growing world population - especially in urban areas such as around Oltmannsstraße, where arable land is as common as fresh vegetables in school canteens. Hydroponics systems enable vegetables to be grown without soil: the plants only grow with the help of water and nutrients. The latter comes from fish feces, for example, which is widely used in fish farming and is called aquaponics in technical jargon. The feces that are filtered out are converted to nitrate with the help of microbes and used as fertilizer, which is mixed with the useful water of the animals and allows the tomatoes and cucumbers to thrive in the adjacent bed. The water separated from the plants then flows back into the basin - this is how the material cycle goes. P 3 boss David Rösch wanted that too.
The regional energy service provider Badenova supported the project with 110,000 euros, P 3 then designed a prototype, on the styrofoam walls of which lettuce grew, which the staff consumed at a large salad party in autumn. But the breakthrough was not yet: And so we continued to tinker. The employees and trainees converted two old containers into a greenhouse. There they put their further developed system, consisting of two elements.
The origin of the fertilizer takes getting used to
The outer structure is reminiscent of narrow wooden tents, and inside there is a pool with water that sprinkles the walls every two minutes. Better said: the free-floating roots of the salads (now: lettuce and Lollo Rosso), whose seedlings are in the holes in the sloping walls. In fact, it's aeroponics because the roots are in the air.
Fish tanks are currently not feasible, says David Rösch. So where do the nutrients come from? P 3 is currently getting the fertilizer from a company in Switzerland that processes human urine. This also follows the principle of the material cycle. So far, the social acceptance of hydroponics systems has generally been rather low. The tenor of the people is rather: "It's feed from the laboratory, grown-up, we want real vegetables from the field!" When asked how long it would take for consumers to accept this alternative cultivation, Rösch replied: "Boah, long!" And urine fertilizer as a source of nutrients doesn't make it better at first.
Systems are suitable for locations in an urban environment
The advantages of the system are obvious: it can stand on flat roofs in the middle of the city. In comparison to the usual arable cultivation, the duration of growth is constant and the space requirement is reduced to a fifth. Because of the cycle, 90 percent less water would be used - "This is relevant in many countries around the world," says Rösch: "And the taste of the salad is perfect." It takes a while before you can try this on the new harvest: it takes around ten weeks from seedling to ready-to-eat lettuce.
"People have to get to know this cultivation better."David RöschDavid Rösch now wants to do a lot of educational work, such as collaborations with schools. The idea of a gardener community is in the room: "People have to get to know this cultivation better." Tomatoes, cucumbers, and herbs are also expected to soon grow in the hydroponics plant. Perhaps the company would sell some of the products in its workshop, but marketing would not be in the foreground. There are many other ideas that keep Rösch busy, not just those with their own fish tank, which could easily be connected. Initially, however, there will probably be an internal salad party - if Corona allows it.
Lead Photo: David Rösch with his steep slope salad breeding, which he sees primarily as an educational project. Photo: Thomas Kunz