The experiment, carried out on a forest and arable light-textured soil, was designed to study the temperature response of autotrophic and heterotrophic N2O production and investigate how the N2O flux relates to soil respiration and O2 consumption. Although N2O production seemed to be stimulated by a temperature increase in both soils, the relationship between production rate and temperature was different in the two soils. This seemed to depend on the different contribution of nitrification and denitrification to the overall N2O flux. In the forest soil, almost all N2O was derived from nitrification, and its production rate rose linearly from 2 °C to 40 °C. A stronger effect of temperature on N2O production was observed in the arable soil, apparently as a result of an incremental contribution of denitrification to the overall N2O flux with rising temperature. The soil respiration rate increased exponentially with temperature and was significantly correlated with N2O production. O2 consumption stimulated denitrification in both soils. In the arable soil, N2O and N2 production increased exponentially with decreasing O2 concentration, though N2O was the main gas produced at any temperature. In the forest soil, only the N2 flux was related exponentially to O2 consumption and it outweighed the rate of N2O production only at >34°C. Thus, it appears that in the forest soil, where nitrification was the main source of N2O, temperature affected the N2O flux less dramatically than in the arable soil, where a temperature increase strongly stimulated N2O production by enhancing favourable conditions for denitrification.
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