Influence of soil moisture on codenitrification fluxes from a urea-affected pasture soil
AuthorClough, Timothy J.
de Klein, Cecile
Bakken, Lars R.
Richards, Karl G.
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CitationClough, T., Lanigan, G., de Klein, C., Samad, M., Morales, S., Rex, D., Bakken, L., Johns, C., Condron, L., Grant, J. and Richards, K. Influence of soil moisture on codenitrification fluxes from a urea-affected pasture soil. Scientific Reports, 2017, 7(1). doi: https://dx.doi.org/10.1038/s41598-017-02278-y
AbstractIntensively managed agricultural pastures contribute to N2O and N2 fluxes resulting in detrimental environmental outcomes and poor N use efficiency, respectively. Besides nitrification, nitrifier-denitrification and heterotrophic denitrification, alternative pathways such as codenitrification also contribute to emissions under ruminant urine-affected soil. However, information on codenitrification is sparse. The objectives of this experiment were to assess the effects of soil moisture and soil inorganic-N dynamics on the relative contributions of codenitrification and denitrification (heterotrophic denitrification) to the N2O and N2 fluxes under a simulated ruminant urine event. Repacked soil cores were treated with 15N enriched urea and maintained at near saturation (−1 kPa) or field capacity (−10 kPa). Soil inorganic-N, pH, dissolved organic carbon, N2O and N2 fluxes were measured over 63 days. Fluxes of N2, attributable to codenitrification, were at a maximum when soil nitrite (NO2−) concentrations were elevated. Cumulative codenitrification was higher (P = 0.043) at −1 kPa. However, the ratio of codenitrification to denitrification did not differ significantly with soil moisture, 25.5 ± 15.8 and 12.9 ± 4.8% (stdev) at −1 and −10 kPa, respectively. Elevated soil NO2− concentrations are shown to contribute to codenitrification, particularly at −1 kPa.
FunderNew Zealand Government; Teagasc Walsh Fellowship Programme
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