Tea Bag Index

All research projects on the soil claim to “involve” those who live on that land. We put the word into inverted commas because often the involvement is only notional. Furthermore, the specialized soil experts find it difficult to communicate with those who use and tread on the soil without thinking too much about it. This is why the approach taken by some European researchers takes on greater meaning.

The Tea Bag Index involves individuals who decide to participate directly and giving them a task to do. There is no magic and no need to do specialist courses. All participants need to do is take an ordinary teabag, measure it, bury it in the ground whose vitality one wants to assess, dig it up after three months and measure it again, then send the information obtained to the University of Utrecht lab, which will record it and put it into a database that will slowly acquire a global character.

What is achieved by doing this? It enables us to analyse the speed of organic decomposition.

Plants thrown on the ground decompose naturally. Attacked by insects and microorganisms, they quickly lose water and release CO2 into the atmosphere. The faster the decomposition, the more carbon dioxide reaches the atmosphere. The slower the decomposition, the more carbon accumulates in the soil. Naturally, the speed of decomposition depends on many factors: the type of vegetation, climate, location, humidity, acidity. Much of this data is already known for many types of soil and is available to researchers. We do not know, however, the speed at which organic materials decompose in the various types of soil. This is why individual citizens are being invited to participate. In order to obtain comparable data, all you have to do is take two teabags (one of green tea, one of redbush), weigh them and bury them at a depth of 8 cm in a piece of land (not the garden). Dig them up after three months, measure them again and send the data electronically to the lab in Holland. The Tea Bag Index thus obtained will allow researchers to build and compare the information as it is collected and refine our understanding of how soils work, linked to changes in climate. Two parameters will be calculated for every type of soil: Stabilization (S) that is the degree to which the tea breaks down, and the speed with which this happens (k).

A global map is slowly being built up which allows us to see and compare the Index across the world.

It is interesting to note that this citizen science approach has been adopted in some countries for students in primary and secondary schools. It has shown itself to be a useful teaching tool that brings to practical life theories and data that otherwise might seem to the students to be purely theoretical.

Further details can be found here and a description of the scientific method HERE