Urine makes hydroponic tomatoes even tastier?!

According to scientists at the University of Ghent, tomatoes grown with algae have more flavor than conventionally grown tomatoes. The algae are made with the help of urine and are used to improve the recycling of fertilizers.

In Flanders, as much as 86% of applied fertilizers are lost during the cultivation of crops. Only 14% of fertilizers effectively reach the consumer in the form of food. The rest of the fertilizer ends up in waste streams or enters the water or the atmosphere, which creates environmental problems.

To counteract this loss of fertilizers and reduce the environmental impact of food production, researchers at Ghent University studied how fertilizers can be recovered from waste streams.

A fertilizer waste stream could be found close by according to researcher Joeri Coppens: "Urine contains most of the nitrogen and phosphorus contained in domestic waste water and delivers these substances in concentrated form. Using a biological stabilization process we succeeded in transforming human urine into a stable and safe nutrient solution. This solution turned out to be extremely suitable for the cultivation of microalgae. These microalgae also known as Spirulina were found to be rich in valuable proteins."

These microalgae were then used as organic fertilizer in tomato cultivation. The outcome was remarkable. Coppens: "The greenhouse test showed that algae-tomatoes contain 30% more sugars and 70% more natural color pigments compared to standard tomatoes. This makes algae-tomatoes redder and sweeter than conventionally grown tomatoes."

The results are not only relevant on earth but also raised the interest of the European Space Agency (ESA). Coppens: "This way of recycling fertilizers offers prospects for growing food on the moon or during a manned mission to Mars." 

The production of algae from urine to later use them as fertilizer for crop cultivation is a unique combination of cleantech and greenhouse cultivation. The researchers are currently working on the further development of the project in collaboration with a number of industrial partners.

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