A Rapid and Accurate Method for Estimating the Temperature Sensitivity of Soil Organic Matter (Q10)

The carbon flux from soil organic matter degradation is significant and could increase with climate change, with a potential retroactive effect. The change in CO₂ emissions from soils due to temperature variations can be estimated using the Q₁₀ parameter, which measures how sensitive the rates of chemical reactions or biological processes are to temperature changes. This is a key parameter for estimating the effects of climate change on soil carbon fluxes and is used in many global carbon models, often as fixed values, although it appears to vary widely among ecosystems. Data currently available in the literature are difficult to compare, as they are based on different approaches and analytical protocols. In this study, the two most commonly used laboratory methods, equal-time and sequential, were compared using a respiration measurement system (respirometer). The results, based on different soils, are in agreement with the literature. The equal-time method provides better exponential adjustments for calculating Q₁₀ values. This approach also minimises potential biases caused by a reduction of available nutrients and/or changes in microbial community structure during the measurement period. For future studies of temperature sensitivity, we recommend the use of the equal-time method with a pre-incubation period, a high measurement frequency, and an incubation time not exceeding 24 h per temperature and sample. This work is based on an automated multi-position respirometer and can be adapted to any other CO₂ monitoring instruments.