Purpose

The current study aimed to (1) investigate the responses of N gases (NO, N₂O, and N₂) and mineral N (NH₄⁺, NO₂⁻, and NO₃⁻) to the different O₂ availability; (2) better understand the importance of O₂ availability on N₂O production pathways; and (3) provide evidence for making N₂O mitigation measures in this agricultural soil.

Materials and methods

An incubation experiment with a fluvo-aquic soil was conducted using a robotized incubation system, with two added nitrogen sources (NH₄⁺, NO₂⁻) under two initial O₂ concentrations (21% and 0% v/v). Gas samples (3.5 ml) were collected every 8 h during the incubation, and soil samples were destructed collected at the beginning and the end of the incubation.

Results and discussion

Under initial condition of 21% O₂, NH₄⁺ combined with NO₂⁻ increased N₂O emission especially at high NH₄⁺ concentration (150 mg N kg⁻¹). It is possibly because strong nitrification with high NH₄⁺ addition caused a low O₂ availability (< 6.2% v/v) which might have stimulated nitrifier denitrification or denitrification with N₂O emission, and under initial condition of 0% O₂, denitrification and anammox were the dominant processes, and N loss via gas depended on NO₂⁻ and NO₃⁻ concentration in the soil. Anammox might occur when NH₄⁺ and NO₂⁻ were present, and this process should not be overlooked under anaerobic condition at the studied soil.

Conclusions

O₂ controlled the soil microbiome processes in the fluvo-aquic soil under current conditions. Under aerobic condition, nitrification and nitrification-related process (nitrifier denitrification or denitrification) were the main N₂O sources, and the nitrogenous gas kinetics depended on the rates of exogenous N and N types; while under anaerobic condition, denitrification contributed the most N₂O and N₂ production, which closely related with NO₂⁻ and NO₃⁻ concentration in the soil.

中文翻译：

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使用机器人孵化系统，氧浓度调节潮土中的NO，N 2 O和N 2动力学以及氮转化

目的

目前研究的目的是（1）调查Ñ气体的反应（NO，N ₂ O，和N ₂）和无机氮（NH ₄ ⁺，NO ₂ ^-和NO ₃ ^- ）的不同ö ₂可用性; （2）更好地了解O ₂可用性对N ₂ O生产途径的重要性；（3）为在该农业土壤中采取N ₂ O缓解措施提供证据。

材料和方法

用潮土的孵育实验用机器人系统的孵育进行，两个添加的氮源（NH ₄ ⁺，NO ₂ ^- ）下两个初始Ô _2种浓度（21％和0％V / V）。孵育期间每8小时收集一次气体样品（3.5 ml），并在孵育开始和结束时破坏土壤样品。

结果与讨论

下21％的O初始条件₂，NH ₄ ⁺与NO合并₂ ^-提高了氮肥₂ O排放尤其是在高NH ₄ ⁺浓度（150毫克N-千克^-1）。可能是因为添加大量NH ₄ ^+的强硝化作用导致O ₂利用率低（<6.2％v / v），这可能会刺激硝化器反硝化或N ₂ O排放的反硝化，并且初始条件为0％O ₂，脱氮和厌氧氨氧化为优势过程，并且经由气体N损失依赖于NO ₂ ^-和NO ₃⁻土壤中的浓度。厌氧氨氧化时NH可能发生₄ ⁺和NO ₂ ^-存在，而这个过程不应该被厌氧条件下，在所研究的土壤忽视。

结论

在当前条件下，O ₂控制潮潮土壤中的微生物组过程。在有氧条件下，硝化和与硝化有关的过程（硝化器反硝化或反硝化）是主要的N ₂ O来源，而氮气的动力学取决于外源N和N的类型。而厌氧条件下，脱硝贡献大多数N- ₂ O和N ₂的生产，这与NO密切相关的₂ ^-和NO ₃ ^-中的土壤浓度。