Does extending the incubation period really improve the accuracy of the Tea Bag Index as a measure of soil health?

The Tea Bag Index (TBI) approach was proposed as a simplified method for determining two key indices: the decomposition constant k and the stabilization factor S. In recent years, this method has gained increasing popularity within the field of soil health assessment. Hayes et al. (2024) proposed that extending the incubation period could enhance the accuracy of the TBI approach. However, this recommendation is misleading, as evidenced by the fact that the extended incubation period resulted in greater deviation of the decomposition curves from the observed data. Hayes et al. (2024) also introduced a new metric, termed “biological decomposition,” which represents the simple mass loss ratios of both green and rooibos teas. They suggested to use this metric instead of calculating the TBI. While I fully agree with their recommendation to avoid using the TBI, the rationale for this recommendation should not rely on the reasoning presented by Hayes et al. (2024). Instead, the avoidance of the TBI metrics should be attributed to their fundamental inaccuracy due to biased assumptions.