High-resolution denitrification kinetics in pasture soils link N₂O emissions to pH, and denitrification to C mineralization
Samad, M. S.; Bakken, L. R.; Nadeem, S.; Clough, Timothy J.; de Klein, C. A. M.; Richards, K. G.; Lanigan, G. J.; Morales, S. E.
Denitrification in pasture soils is mediated by microbial and physicochemical processes leading to nitrogen loss through the emission of N₂O and N₂. It is known that N₂O reduction to N₂ is impaired by low soil pH yet controversy remains as inconsistent use of soil pH measurement methods by researchers, and differences in analytical methods between studies, undermine direct comparison of results. In addition, the link between denitrification and N₂O emissions in response to carbon (C) mineralization and pH in different pasture soils is still not well described. We hypothesized that potential denitrification rate and aerobic respiration rate would be positively associated with soils. This relationship was predicted to be more robust when a high resolution analysis is performed as opposed to a single time point comparison. We tested this by characterizing 13 different temperate pasture soils from northern and southern hemispheres sites (Ireland and New Zealand) using a fully automated- high-resolution GC detection system that allowed us to detect a wide range of gas emissions simultaneously. We also compared the impact of using different extractants for determining pH on our conclusions. In all pH measurements, soil pH was strongly and negatively associated with both N₂O production index (IN₂O) and N₂O/(N₂O+N₂) product ratio. Furthermore, emission kinetics across all soils revealed that the denitrification rates under anoxic conditions (NO+N₂O+N₂ μmol N/h/vial) were significantly associated with C mineralization (CO₂ μmol/h/vial) measured both under oxic (r² = 0.62, p = 0.0015) and anoxic (r² = 0.89, p<0.0001) conditions.... [Show full abstract]
Keywordsdenitrification kinetics; denitrification; pasture soils; soil; N₂O emissions; N₂O; C mineralization; pH; General Science & Technology; Carbon; Oxygen; Nitrogen; Nitric Oxide; Nitrous Oxide; Soil Microbiology; Anaerobiosis
Fields of Research0503 Soil Sciences; 050304 Soil Chemistry (excl. Carbon Sequestration Science)
© 2016 Samad et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Attribution-NonCommercial-NoDerivatives 4.0 International
CitationSamad, M. S., Bakken, L. R., Nadeem, S., Clough, T. J., de Klein, C. A., Richards, K. G., . . . Morales, S. E. (2016). High-resolution denitrification kinetics in pasture soils link N₂O emissions to pH, and denitrification to C mineralization. PloS one, 11(3), 10.1371/journal.pone.0151713
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