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<p>Purpose. Nitrogen (N) supply from soil and atmospheric N deposition is important to assess the quality of Chinese-fir clones in unfertilized forests, while also contributing to greenhouse gas emissions, particularly nitrous oxide (N₂O). The objective of this study is to investigate how Chinese-fir clones affect responses of soil N transformations and N<sub>2</sub>O emissions to N deposition. Methods. An aerobic incubation experiment was conducted to quantify the net rates of soil N mineralization (NMR) and nitrification (NNR), as well as N<sub>2</sub>O emissions, of seven Chinese-fir clones subjected to N addition rates of 0, 30, 60, and 90&#xa0;kg N per hectare per year (kg N ha<sup>− 1</sup> a<sup>− 1</sup>). Results. Generally, N addition significantly increased NMR at the high rate (&gt; 30&#xa0;kg N ha<sup>–1</sup> a<sup>–1</sup>), but fluctuated NNR without significant changes. Both NMR and NNR were significantly and positively correlated with soil N-to-phosphorus (P) ratio (N/P) and carbon (C)-to-P ratio (C/P), but were negatively related to pH and P availability. Cumulative N<sub>2</sub>O emissions increased with increasing N addition rate. The structural equation model revealed that the response of N<sub>2</sub>O emission to N addition (response ratio (RR) of N<sub>2</sub>O to N addition RR(N<sub>2</sub>O)) was directly driven by the response of NMR/NNR to N addition (RR(NMR/NNR)) and was predominantly regulated by pH. The increase in pH and C/P stimulated the NMR response to N addition (RR(NMR)), which elevated RR(NMR/NNR) and, in turn, increased RR(N<sub>2</sub>O). Conclusions. This study suggested that soil pH and nutrient stoichiometry are the predominant factors regulating the responses of soil N transformations to N addition, and consequently, the resulting changes in N<sub>2</sub>O emissions.</p>

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Responses of Soil Nitrogen Transformations and Nitrous Oxide Emissions to N Addition as Affected by Chinese-fir Clones

  • 期刊论文

  • 发表日期：

    2025年11月28日

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  • Jing Wang,
  • Miaomiao Cao,
  • Qiang Liu,
  • Xueyan Zheng,
  • Hui Xiao,
  • Renhua Zheng,
  • Jinhui Chen,
  • Jiake Zhou,
  • Liangping Wu,
  • Uwiragiye Yves,
  • Ahmed S. Elrys,
  • Meiqi Chen,
  • Hang Jing,
  • Yi Cheng

摘要

Purpose. Nitrogen (N) supply from soil and atmospheric N deposition is important to assess the quality of Chinese-fir clones in unfertilized forests, while also contributing to greenhouse gas emissions, particularly nitrous oxide (N₂O). The objective of this study is to investigate how Chinese-fir clones affect responses of soil N transformations and N2O emissions to N deposition. Methods. An aerobic incubation experiment was conducted to quantify the net rates of soil N mineralization (NMR) and nitrification (NNR), as well as N2O emissions, of seven Chinese-fir clones subjected to N addition rates of 0, 30, 60, and 90 kg N per hectare per year (kg N ha− 1 a− 1). Results. Generally, N addition significantly increased NMR at the high rate (> 30 kg N ha–1 a–1), but fluctuated NNR without significant changes. Both NMR and NNR were significantly and positively correlated with soil N-to-phosphorus (P) ratio (N/P) and carbon (C)-to-P ratio (C/P), but were negatively related to pH and P availability. Cumulative N2O emissions increased with increasing N addition rate. The structural equation model revealed that the response of N2O emission to N addition (response ratio (RR) of N2O to N addition RR(N2O)) was directly driven by the response of NMR/NNR to N addition (RR(NMR/NNR)) and was predominantly regulated by pH. The increase in pH and C/P stimulated the NMR response to N addition (RR(NMR)), which elevated RR(NMR/NNR) and, in turn, increased RR(N2O). Conclusions. This study suggested that soil pH and nutrient stoichiometry are the predominant factors regulating the responses of soil N transformations to N addition, and consequently, the resulting changes in N2O emissions.