References

130 O. Dilly
Under aerobic conditions, respiration encompasses the glycolysis and the
subsequent oxidative decarboxylation of pyruvate feeding into the citric
acid cycle coupled to a respiratory chain. When all these reactions are
fullyinvolvedandalternativeelectronacceptorslikeNO − 3 ,Fe3+ , ... are
hardly used, the respiratory quotient (RQ) for substrates such as glucose
is 1. Under these conditions, degradation of the substrate is considered
as complete since a number of moles of CO2 are consumed as O2 are
evolved. However, soil contains a wide spectrum of substrates that may be
transformed and immobilised, and their complete oxidation may also be
retarded by environmental and nutritional factors. Thus, soil management
maymodifytherespiratoryquotient.
Fig. 4. Respiratory quotient of the topsoil from an eutric Arenosol under crop rotation in the
Bornhöved Lake district, Germany, during basal respiration (BAS) and substrate-induced
respiration from 0–4 h (MIRR maximal initial respiratory response) and 4–24 h (Growth);
substrate rate was 5 mg glucose g −1 soil, soil was preconditioned with 1.5 and 0.2% oat straw
for 46 days at 22 ◦ C