The educational App Tea Bag Index (TBI) collects data on soil observations and on soil decomposition dynamics in particular. The decomposition of organic matter in the soil is part of the global carbon cycle that provide information on the biological activity of the soil and is therefore important for climate change. Changes in the carbon content of soil can both intensify and mitigate climate change.

The citizen scientists may choose from 3 activities: 1) basic soil observations by recording soil colour, soil life and land use, 2) soil observations by studying soil texture by feel of doing the Spade test, 3) TBI. The TBI records the decomposition rates of buried tea bags (green tea and rooibos) within 3 months using a standardised method. The method can easily be performed by citizen scientists, such as students. The collected data is transmitted to the database of the Global Tea Bag Index Network (

Schools can easily include the TBI App in their curriculum. Teaching materials (soil observation with all senses, spade test, soil texture by feel, TBI) in the App increase the students´ knowledge of soil and the global carbon cycling.
Tea Bag Index App will further contribute to a strong connection between science and society by connecting each one of the activity categories to the Sustainable Development Goals (SDGs).

The Tea Bag Index app runs on the SPOTTERON Citizen Science platform.

What’s New

Version 2.9.2

* Extended info text "about the project"
* Minor bug fixes

App Privacy

The developer, SPOTTERON Gmbh, has not provided details about its privacy practices and handling of data to Apple. For more information, see the developer's privacy policy.

No Details Provided

The developer will be required to provide privacy details when they submit their next app update.


31 MB

Requires iOS 11.0 or later. Compatible with iPhone, iPad, and iPod touch.


English, German

Age Rating


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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