36,000 buried tea bags – Umeå researcher’s crazy idea becomes a global hit

It’s a normal workday at Utrecht University in the Netherlands in 2009, and researcher Judith Sarnell brings a bag of mosquito nets to the coffee break. She regularly uses these tools to study the decomposition of plant matter, but she sees something in the coffee room that makes her think in new ways.

– I realized that tea also contains plant matter. Then we came up with the idea that you can bury the tea bags, she tells Dagens ETC.

The audience participated in it.

A few years later, Judith Sarnell and fellow researchers in the Netherlands and Austria developed a new method for studying decomposition processes in tea bags—and secured funding to get the public involved in the project.

“The concept is that anyone can bury the bags. Then they are dug up again three months later, weighed and sent to us and other researchers,” she says.

In the soil, the tea is decomposed by living organisms, but the bag itself remains intact, because it is made of plastic. By recording the weight loss, researchers can study the rate of decomposition.

Data collection from 36,000 tea bags

Cuba, Costa Rica, Greenland, South Africa, Australia, Italy, India. Since the project opened to the public in 2015, approximately 36,000 bags of green tea and rooibos tea have been buried around the world.

Since then, thousands of school students, researchers, and individuals have submitted their own data to Judith Sarnell and her colleagues.

– For schools, burying tea bags is simple and educational. In Sweden, about 250 classrooms have been involved, and in the rest of the world there are a few more, says Judith Sarnell.

The results of the study have now been published in an article in the scientific journal Ecology Letters. According to Judith Sarnell, the researchers were able to pinpoint the complex interactions that control the decomposition of plant material, and found new patterns in cold regions and soils used for agriculture.

“We now have a tool that makes it easier for us to understand the state of the Earth and how active it is,” she says. “We can now also compare our new data to reference values.”