Soil NO 3 level and O 2 availability are key factors in controlling N 2 O reduction to N 2 following long-term liming of an acidic sandy soil

Mehmet Senbayram, Alice Budai, Roland Bol, David Chadwick, L. Márton, Recep Gündogan, Di Wu

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Liming of acidic soils has been suggested as a strategy to enhance N 2 O reduction to N 2 during heterotrophic denitrification, and mitigate N 2 O emission from N fertilised soils. However, the mechanisms involved and possible interactions of key soil parameters (NO 3 and O 2 ) still need to be clarified. To explore to what extent soil pH controls N 2 O emissions and the associated N 2 O/(N 2 O + N 2 ) product ratio in an acidic sandy soil, we set-up three sequential incubation experiments using an unlimed control (pH 4.1) and a limed soil (pH 6.9) collected from a 50-year liming experiment. Interactions between different NO 3 concentrations, N forms (ammonium- and nitrate) and oxygen levels (oxic and anoxic) on the liming effect of N 2 O emission and reduction were tested in these two sandy soils via direct N 2 and N 2 O measurements. Our results showed 50-year liming caused a significant increase in denitrification and soil respiration rate of the acidic sandy soil. High concentrations of NO 3 in soil (>10 mM N in soil solution, equivalent to 44.9 mg N kg −1 soil) almost completely inhibited N 2 O reduction to N 2 (>90%) regardless of the soil pH value. With decreasing NO 3 application rate, N 2 O reduction rate increased in both soils with the effect being more pronounced in the limed soil. Complete N 2 O reduction to N 2 in the low pH sandy soil was also observed when soil NO 3 concentration decreased below 0.2 mM NO 3 . Furthermore, liming evidently increased both N 2 O emissions and the N 2 O/(N 2 +N 2 O) product ratio under oxic conditions when supplied with ammonium-based fertiliser, possibly due to the coupled impact of stimulated nitrification and denitrification. Overall, our data suggest that long-term liming has the potential to both increase and decrease N 2 O emissions, depending on the soil NO 3 level, with high soil NO 3 levels overriding the assumed direct pH effect on N 2 O/(N 2 +N 2 O) product ratio.

Original languageEnglish
Pages (from-to)165-173
Number of pages9
JournalSoil Biology and Biochemistry
Volume132
DOIs
Publication statusPublished - May 1 2019

Keywords

  • Denitrification product ratio
  • Liming
  • N
  • N O
  • Nitrate

ASJC Scopus subject areas

  • Microbiology
  • Soil Science

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