where a ¼ (Afructose or vanillin Asample)/(Afructose or vanillin Acontrol), Q
is the amount of CO2 in the flask’s atmosphere in mg CO2eC kg1
dried soil and Afructose or vanillin, Asample and Acontrol represent the
isotopic abundance of fructose or vanillin, of CO2 in the sample
headspace and of CO2 in headspace of control samples (i.e. samples
to which water was added rather than labelled substrate), respectively.
The mineralisation of labelled substratewas calculated using
the following equation