Carbon (C) substrates are critical for regulating denitrification, a process that results in nitrous oxide (N₂O) and dinitrogen (N₂) emissions from soil. However, the impacts of C substrates on concomitant soil emissions of carbon dioxide (CO₂) and N₂O under varying soil types and soil water contents are not well studied. Three repacked Pallic grassland soils, varying in texture and phosphorus (P) status, containing NO₃⁻-¹⁵N were held at three levels of matric potential (ψ, −3, −5 and −7 kPa), while receiving daily substrate additions (acetate, glucose and water control) for 14 days. The CO₂ and N₂O emissions were measured daily. Additionally, the N₂O:(N₂ + N₂O) ratios were determined using ¹⁵N on days 3 and 14. Results showed that N₂O emissions increased exponentially as soil gas diffusivity declined, and N₂O peak emissions were higher with glucose than with acetate addition, with a range (± standard deviation) of 0.1 ± 0.0 to 42.7 ± 2.1 mg N m⁻² h⁻¹. The highest cumulative N₂O emission (2.5 ± 0.2 g N m⁻²) was measured following glucose addition with a soil ψ of −3 kPa. In comparison with added glucose, acetate resulted in a twofold increase in N₂ emissions in soils with relatively low gas diffusivities. The N₂O:(N₂O + N₂) emissions ratios varied with substrate (glucose, 0.91; acetate, 0.81) on day 3, and had declined by day 14 under substrate addition (≤0.10). Cumulative CO₂ emissions were enhanced with increasing soil gas diffusivity and were higher for soils amended with glucose (ranging from 22.5 ± 1.3 to 36.6 ± 1.8, g C m⁻²) than for those amended with acetate. Collectively, the results demonstrate that the increase of N₂O, N₂ and CO₂ emissions and changes in the N₂O:(N₂ + N₂O) ratio vary over time in response to C substrate type and soil gas diffusivity.

中文翻译：

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在不同土壤基质势下用碳底物修正的三种土壤中一氧化二氮、二氮和二氧化碳的排放

碳 (C) 底物对于调节反硝化作用至关重要，反硝化作用会导致土壤中的一氧化二氮 (N ₂ O) 和二氮 (N ₂ ) 排放。然而，在不同土壤类型和土壤含水量下，碳底物对二氧化碳 (CO ₂ ) 和 N ₂ O伴随土壤排放的影响尚未得到很好的研究。三个重新包装的 Pallic 草原土壤，质地和磷 (P) 状态各不相同，含有 NO ₃ ^- - ¹⁵ N，保持在三个基质势水平（ψ、-3、-5 和 -7 kPa），同时每天接受底物添加(醋酸盐、葡萄糖和水对照) 14 天。CO ₂和 N ₂每天测量 O 排放量。此外，在第3 天和第 14 天使用¹⁵ N确定N ₂ O:(N ₂  + N ₂ O) 比率。结果表明，随着土壤气体扩散率下降，N ₂ O 排放呈指数增加，并且 N ₂ O 排放峰值更高使用葡萄糖而不是添加醋酸盐，范围（± 标准偏差）为 0.1 ± 0.0 至 42.7 ± 2.1 mg N m ^-2  h ^-1。最高累积 N ₂ O 排放量 (2.5 ± 0.2 g N m ^-2 ) 在添加葡萄糖后测量，土壤ψ为 -3 kPa。与添加的葡萄糖相比，醋酸盐导致 N 增加了两倍₂气体扩散率相对较低的土壤中的排放。N ₂ O:(N ₂ O + N ₂ ) 排放比在第 3 天随底物（葡萄糖，0.91；乙酸盐，0.81）而变化，并且在第 14 天添加底物（≤0.10）时下降。累积CO ₂排放随着土壤气体扩散率的增加而增加，并且用葡萄糖修正的土壤（范围从22.5 ± 1.3 到36.6 ± 1.8，g C m ^-2）高于那些用醋酸修正的土壤。总的来说，结果表明，n的增加₂ O，N ₂和CO ₂的排放量和变化在N ₂ ○：（N ₂  + N ₂O) 比率随时间变化，以响应 C 基质类型和土壤气体扩散率。