The tea bag index provides a highly standardized reference method for any decomposition study. We use Lipton Green tea and Rooibos tea that comes in plastic mesh bags, and bury them for 3 months at 8 cm depth. Next to using tea as a standard litter, you can use the weight loss of green tea and Rooibos tea to calculate two decomposition parameters, by which you can fit a two phased decay curve. The details of this are explained in our publication in Methods in Ecology and evolution (Keuskamp et al., 2013).
This website contains details on the method, tips and tricks and the ways to obtain tea under ‘method’. Be aware that the method described here is somewhat simplified to address a wider public. A more extended protocol can be found as a download at the method page.
The method has been successfully used to obtain measurements along gradients and to test experimental treatments in greenhouse potting studies and mesocosms. Researchers are challenged to test the usefulness of the method in their own scientific set up. As it a relatively new method, we are keen on learning from your experiences.
Our goal is to create a global soil map of decomposition and we are happy to receive data that was obtained following our protocol in natural soils and under ambient conditions. If you think you make a significant contribution to our database (either by the amount of locations or by adding rare but important locations) you can apply for co-authorship. Please read the details about our call.
On this website you will find the standardized excel sheet that will help you to calculate the TBI parameters. This file can also be uploaded into our database under ‘submit multiple datapoints’, but currently, they will not be displayed on the web-based map.
Lipton changed the fabric of the bags in 2017, from woven, nylon mesh into non-woven bags from polyethylene terephthalate (PET), while the tea inside has remained the same. We therefore launched TBI 2.0, where we will collect data from the non-woven bags. Within Teatime4science, we collect only decomposition data from woven nylon mesh bags, as we think that the new mesh size will result in unknown interactions and comparison cannot be achieved with a simple conversion factor. You are therefore encouraged to submit your data both from woven nylon mesh and non-woven bags, but please clearly indicate which tea bags you used. The data of non-woven bags collected in TBI 2.0 will become our future reference data set, and we plan to analyze the differences between the woven and unwoven tea bags.
p.s. We can also offer several projects for students. We have several projects available this summer (2017). Email Taru if you are interested in working with farmers in Austria, Judith when you would like to investigate the microbial community in Italy or Sweden, and Mariet when you want to study long term decomposition.