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This spring, residents of Leiden can take part in a soil study during the citizen science project 'Tulip Mania’. With the project, DNA researcher Leonie Kaptein and partner Leiden Centre for Applied Bioscience (LCAB) (Hogeschool Leiden) want to learn more about the biodiversity in garden and potting soil.

For this, the Hortus sells a special organic bulb mix with the bright red Tulipa 'Masterpeace'. Buyers have the chance to win a scientific analysis of their garden or potting soil. The lucky winners are determined in a special way: one of the tulips in the bag has a different colour.

The experiment also takes place in the Hortus. In the garden there are five tubs with soil from the tulip grower and five tubs with soil from Leiden, in which the red tulips were already planted on 24 November. Last Sunday, during the Winter Afternoon, the deviant tulips were also planted, so that participants can see in the spring how the deviant tulip should look like. The planting moment was attended by those involved in the project, among them Leonie Kaptein herself, but also leader of the project at the Leiden Centre for Applied Bioscience (LCAB) Arjen Speksnijder, Carla Teune and Theo Houthoff on behalf of the Hortus, artist Rafael Martig and other green fanatics.

The goal of the Tulipmania citizen science research is to make invisible and partly unknown underground biodiversity visible. How do you find out how many types of micro-organisms there are in a soil? That has long been a major problem and a reason why micro-organisms have remained underexposed when it comes to determining the richness of species on earth and the importance of biodiversity. With the help of metagenomics, the total DNA package from an ecosystem can be mapped in a single test.

Read more about the project at

Photos: Simone Both.

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