Identifying the sources of nitrous oxide (N₂O) and carbon dioxide (CO₂) production from soil is central to enhancing the understanding and prediction of these emissions to the atmosphere. The magnitude of N₂O and CO₂ production derived from soil organic matter (SOM) can asymmetrically change due to stimuli from root exudation and nitrogen additions ‒ a response termed the priming effect. We conducted an incubation to examine the effects of N and artificial root exudate (ARE) additions on the priming of SOM. We also evaluated the changes in N₂O production from nitrification and denitrification by measuring ¹⁵N–N₂O site preference (SP). ARE consisted of a mixture of 99 atom% ¹³C labelled compounds at three rates (0, 6.2, 12.5 mg C kg⁻¹ soil day⁻¹) applied daily to microcosms with or without urea, a subset of which was also labelled with 5 atom% ¹⁵N. Additions of ARE or urea alone caused positive priming effects; however, addition of ARE and urea concurrently resulted in an antagonistic interactive effect that diminished the N₂O production derived from SOM mineralization (P < 0.05). Moreover, CO₂ production from SOM decreased in urea-treated microcosms (P < 0.01) such that all soils receiving ARE and urea exhibited reduced positive priming relative to their unfertilized counterparts. Based on SP results, the contributions of denitrification and nitrification to total N₂O production were both amplified due to the combined inputs of ARE and urea compared to the untreated control (49.9 ± 10.1 and 28.3 ± 8.0 μg N₂O–N kg⁻¹, respectively). In soils receiving only ARE, N₂O derived from denitrification decreased relative to a control, thus reducing overall N₂O production (−9.5 ± 12.3 μg N₂O–N kg⁻¹); conversely, nitrification-derived N₂O was differentially augmented (+17.2 ± 9.0 μg N₂O–N kg⁻¹). Results indicate that a combination of elevated root exudation with N fertilization has the potential to asymmetrically amplify N₂O emissions due to increases in both nitrification and denitrification sources.

识别土壤中产生的一氧化二氮（N ₂ O）和二氧化碳（CO ₂）的来源对于增强对这些向大气排放的理解和预测至关重要。土壤有机质（SOM）产生的N ₂ O和CO _2的产生量会因根系分泌物和氮的添加而产生不对称变化-这种反应称为启动效应。我们进行了一次培养，以研究N和人工根系分泌物（ARE）添加对SOM引发的影响。我们还通过测量¹⁵ N–N ₂评估了硝化和反硝化过程中N ₂ O产生的变化。O站点首选项（SP）。ARE由99种原子％的¹³ C标记的化合物的混合物组成，分别以三种速率（0、6.2、12.5 mg C kg ^-1土壤第^-1天）施用于有或没有尿素的缩微胶料，其中一部分也用5标记原子％^15N。单独添加ARE或尿素会产生积极的引发作用；但是，同时添加ARE和尿素会产生拮抗作用，从而减少了源自SOM矿化作用的N ₂ O产生（P <0.05）。此外，CO ₂在尿素处理的微观世界中，SOM的产量降低了（P <0.01），因此所有接受ARE和尿素的土壤相对于未施肥的土壤都表现出减少的阳性启动。根据SP结果，与未处理的对照相比（49.9±10.1和28.3±8.0μgN ₂ O–N kg ^−），由于ARE和尿素的组合输入，反硝化和硝化作用对总N ₂ O产生的贡献均被放大^{。 1}）。在仅接受ARE的土壤中，反硝化作用产生的N ₂ O相对于对照减少，从而降低了总N ₂ O产量（-9.5±12.3μgN ₂ O–N kg ^-1）；相反，硝化衍生的N ₂O差异增加（+17.2±9.0μgN ₂ O–N kg ^-1）。结果表明，由于硝化和反硝化源的增加，根系渗出量的增加与氮肥的组合有可能不对称地放大N ₂ O排放。