Fig. 1. Schematic representation of the experimental design. Either Milli-Q water or glucose was added as substrate to soil samples at time ¼ 0. CO2-traps are pink at the start of the incubation period and the color changes to yellow depending on the amount of carbon respired during the incubation. A calibration curve of absorbance versus headspace equilibrium CO2 concentration is used to estimate how much carbon is respired from the system. Heat (Q Sample) is dissipated during the experiment and this is determined by isothermal calorimetry. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)