Redesigning the soil Tea Bag Index methodology for school and citizen science in Australia

Abstract

Context: The Tea Bag Index (TBI) evaluates the rate of organic matter decomposition using Lipton tea bags. However, this tea bag cannot be easily found in Australia, having to be imported from Europe. The 90-day incubation period also poses problems for school and citizen science projects, such as missing tea bags and organism-induced damage. Aims: The study aims to: (1) investigate the suitable alternative Australian tea bag brands for the decomposition studies; (2) assess the potential for reducing the incubation period; and (3) evaluate the priming effects of different substrates on decomposition rate. Methods: The feasibility of two local Australian tea bag brands (Madame Flavour or T2) was compared to Lipton by collecting time-series data over the incubation period in pot experiments with the addition of sugar, citric acid and microplastic. Key results: We found an alternative tea brand that can be used for TBI in Australia. Conclusions: (1) Madame Flavour tea bags can be used as an alternative litter material for the TBI in Australia. (2) The incubation period potentially could be reduced to 21 days, with another sampling taken on day 4 and 14. (3) Although there is a significant difference in decomposition rate between the control and substrates addition, no significant difference in decomposition rate is found among different substrates. Implications: The utilisation of the Madame Flavour tea bag enables the adoption of decomposition studies by a broader spectrum of citizen scientists in Australia.