BERLIN/HALE (dpa) – Rotten tea bags are emerging from the ground again to light up: In a dedicated Berlin park, scientists dug up buried tea bags after a good three months.
Thousands of bags will follow across Germany by the end of October. The researchers want to use their condition to analyze soil activity. Many volunteer participants – citizen scientists – from all over Germany are taking part in the project.
Explains Hans-Jörg Vogel, Head of Soil System Research at the Helmholtz Center for Environmental Research in Halle (Saal).
An important base number is the so-called tea bag index. Shows how quickly soil organisms break down plant debris. To do this, the plant material, in this case green tea and sage tea, is weighed, buried in the ground for three months and then weighed again after excavation. The teabag index can be calculated from the difference between the starting and ending weight of the teabags.
According to Vogel, tea bags from the Berlin allotment park show a high level of biological activity. Green tea bags would have lost half their weight. “With rooibos tea, the weight loss was our third,” Vogel said. Rooibos tea is difficult to break down due to its consistency. Federal Research Minister Anya Karlicic (CDU) buried the first tea bags in the allotment park in April.
According to Vogel, 4,500 campaign groups were sent across Germany. “The response has been tremendous,” says the scientist. All groups were dispatched after a short time. One set contains 12 tea bags that the participants must bury in two locations. In addition, citizen scientists must also collect other data, such as the pH value, type of use, or grain size in the soil.
In a few weeks, scientists want to present the first interim results. After the assessment, the data will be incorporated into national and international research projects on sustainable land use.
The Dutch came up with the idea of tea bags a few years ago. In 2018, researchers from around the world buried about 35,000 tea bags. At 570 locations on six continents, they measured the speed of smashing dead plant parts into the forest.
How quickly biomass rot was measured many times before. However, it was always difficult to compare the results because different types of plants were buried in different bags. In Switzerland this year, a government research agency sent 2,000 cotton underwear to gardeners and farmers to check soil quality. This is used to analyze how detailed it is.
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