Exploring decomposition of household items as an inexpensive, yet scientifically-robust, tool for assessing soil health
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Soil health has emerged as both a movement in sustainable agriculture, and a framework for monitoring provisioning of soil ecosystem services. To increase interest and adoption of soil health promoting practices (SHPPs), we must make soil health more accessible to land managers by making soil health indicators less expensive, more informative, and less time-consuming. This study compares the proportion of decomposition (measured as percent mass loss) of green tea, rooibos tea, cotton underwear, and birch craft sticks, which are common household items, to traditional biological soil health indicators. My objectives were to 1) validate decomposition as an indicator of soil health by relating it to traditional indicators and maize yield, and to 2) evaluate the ability of traditional and decomposition indicators to detect differences between SHPPs and conventional practices.
I found that while decomposition indicators were often not related to traditional indicators of soil health, green and rooibos tea decomposition was positively correlated with maize yield, even when decomposed for just four days. In addition, decomposition indicators were able to detect differences in SHPPs at least as well as traditional indicators of soil health. Short-term decomposition of rooibos tea, in particular, showed high ‘signal’ (i.e. treatment effect) and low ‘noise’ (i.e. variability), and performed better than all traditional biological soil health indicators measured in this study. Based on my findings, measuring decomposition of household items was not only inexpensive and easy to use, but also comparable with traditional indicators of soil health with respect to their ‘signal versus noise’, or their ability to detect magnitude of effect of a SHPP compared to spatial variability. This suggests that decomposing household items shows promise as an inexpensive and scientifically-robust method for citizen scientists to measure soil biological activity, which is an important aspect of soil health. My data
further supports educational and outreach benefits of decomposing common household items with citizen scientists, and suggests this method of measuring biological activity could promote synergy between the soil health movement and scientists measuring change in soil ecosystem services.