Oxygen and substrate availability interactively control the temperature sensitivity of CO2 and N 2O emission from soil
2014
Blagodatskaya, Е | Zheng, X. | Blagodatsky, S. | Wiegl, R. | Dannenmann, M. | Butterbach-Bahl, K.
We investigated how oxygen availability, substrate amount, and quality affect the temperature dependency of enzymatic processes involved in the production of carbon dioxide (CO₂) and nitrous oxide (N₂O). Three substrates differing in microbial degradability (glucose with potassium nitrate, glycine, and phenylalanine) were added to a mountain grassland soil at a range of concentrations. Soils were incubated at 21 and 1 % of O₂content and at 10 and 20 °C. Oxygen availability was a main factor controlling the reaction rates and temperature sensitivity of CO₂and N₂O production. The temperature sensitivity of CO₂production was higher under aerobic versus oxygen-limited conditions, and the opposite dependency was observed for the N₂O production. Substrate availability was a second factor affecting the temperature sensitivity of the processes leading to the production of these gases. The temperature response was reduced under substrate limitation. Apparent activation energy for aerobic CO₂production was similar (Eₐ ~ 30 kJ mol⁻¹) for tested substrates, while Eₐfor anaerobic N₂O production increased in the order phenylalanine < glycine < glucose + NO₃⁻having values 45, 75, and 106 kJ mol⁻¹, respectively. Commonly, the temperature sensitivity of N₂O production (2 < Q₁₀ < 4.5) was much higher than that for CO₂(Q₁₀ ≤ 1.5).
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