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Heterotrophic nitrification is responsible for large rates of N2O emission from subtropical acid forest soil in China.
- Source :
- European Journal of Soil Science; Jul2018, Vol. 69 Issue 4, p646-654, 9p
- Publication Year :
- 2018
-
Abstract
- Summary: Subtropical acidic forest soil is an important source of global nitrous oxide (N<subscript>2</subscript>O). However, the rates of autotrophic nitrification and denitrification in such soil are less than in temperate forest soil. We hypothesized that this difference is related to different N<subscript>2</subscript>O production pathways. We carried out paired <superscript>15</superscript>N‐labelling experiments under aerobic conditions (60% water‐holding capacity) in the laboratory to compare N<subscript>2</subscript>O production pathways between subtropical and temperate forest soils to determine the differences in N<subscript>2</subscript>O production based on controlling factors. Our results showed that the contributions of NH<subscript>4</subscript><superscript>+</superscript> oxidation to NO<subscript>3</subscript><superscript>−</superscript> to total N<subscript>2</subscript>O production (C<subscript>NH4</subscript>) were small in all soils studied (21–30%). Contributions of denitrification to total N<subscript>2</subscript>O production (C<subscript>NO3</subscript>) in subtropical forest soil (34%) were significantly less than those in temperate forest soil (54%). However, rates of N<subscript>2</subscript>O emission from denitrification (N<subscript>2</subscript>O<subscript>d</subscript>) were similar between subtropical and temperate forest soils, indicating that denitrification was probably not the predominant process causing the difference between the rates of N<subscript>2</subscript>O production in these soils. The average contribution of heterotrophic nitrification to total N<subscript>2</subscript>O production (C<subscript>ON</subscript>) was significantly larger in subtropical forest soil (45%) than in temperate forest soil (15%). Soil pH and the C:N ratio were identified as key factors, with C<subscript>ON</subscript> negatively correlated with soil pH (r = −0.60, P < 0.05) and positively correlated with soil C:N ratio (r = 0.78, P < 0.01), although the significance was probably weakened when forest types were taken into consideration. The rate of N<subscript>2</subscript>O production by heterotrophic nitrification (N<subscript>2</subscript>O<subscript>h</subscript>) (average, 3.0 μg N kg<superscript>−1</superscript> day<superscript>−1</superscript>) was also significantly larger in subtropical forest soil than in temperate forest soil (average, 0.7 μg N kg<superscript>−1</superscript> day<superscript>−1</superscript>). Therefore, based on this study, the heterotrophic N<subscript>2</subscript>O pathway seems responsible for the larger N<subscript>2</subscript>O production in subtropical acid forest soil than in temperate forest soil. This study is among the first to elucidate in detail contributions to the processes of N<subscript>2</subscript>O production and to account for its large rates of production in subtropical acidic forest soil in China, which has implications for the prediction of N<subscript>2</subscript>O production in forest soil using ecosystem modelling. Highlights: Examined N<subscript>2</subscript>O production pathways in subtropical and temperate forest soils. Rate of N<subscript>2</subscript>O emission in subtropical forest soil was larger than temperate forest soil. Heterotrophic nitrification was responsible for large N<subscript>2</subscript>O production in subtropical soil. Soil pH and C:N ratio were identified as key factors affecting the N<subscript>2</subscript>O production pathway. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 13510754
- Volume :
- 69
- Issue :
- 4
- Database :
- Complementary Index
- Journal :
- European Journal of Soil Science
- Publication Type :
- Academic Journal
- Accession number :
- 130483961
- Full Text :
- https://doi.org/10.1111/ejss.12557