Nitrous oxide (N₂O) dynamics during denitrification, including N₂O production and reduction, particularly as related to soil depth, are poorly understood. The objective of this study was to investigate the rates of N₂O production and reduction processes at various soil depths along a hydrological gradient in grazed subtropical grasslands. A batch incubation study was conducted on soils collected along a hydrological gradient representing isolated wetland (Center), transient edge (Edge) and pasture upland (Upland) in south‐central Florida. Significantly different N₂O production and reduction rates between hydrological zones were observed for surface soils (0–10 cm) under ambient conditions, with average N₂O production rates of 0.368, 0.178 and 0.003 N₂O‐N kg⁻¹ dry soil h⁻¹ for Center, Edge and Upland, respectively, and average N₂O reduction rates of 0.063, 0.132 and 0.002 N₂O‐N kg⁻¹ dry soil h⁻¹. Nitrous oxide production and reduction in subsurface soils maintained low rates and showed small variations between depths and hydrological zones. Our results suggest that N₂O dynamics were affected by depth, mainly through labile organic carbon (C) and microbial biomass C, being influenced by hydrological zone primarily through soil NO₃^‐ content. The spatial distribution of N₂O fluxes from denitrification along the hydrological gradient is likely attributed to the differences in N₂O production and reduction in surface soils.

中文翻译：

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亚热带草原沿水文梯度反硝化过程中的一氧化二氮动力学

人们很少了解反硝化过程中的一氧化二氮（N ₂ O）动力学，包括N ₂ O的产生和还原，特别是与土壤深度有关的动力学。这项研究的目的是调查放牧的亚热带草原在不同土壤深度沿水文梯度的N ₂ O产生和还原过程的速率。对沿佛罗里达南部中部偏远地区的湿地（中心），过渡带（Edge）和牧场高地（Upland）的水文梯度收集的土壤进行了分批孵化研究。在环境条件下，表层土壤（0–10 cm）在水文区之间观察到明显不同的N ₂ O产生和减少速率，平均N ₂中心，边缘和高地的O生产率分别为0.368、0.178和0.003 N ₂ O‐N kg ^-1旱地h ^-1，平均N ₂ O还原速率为0.063、0.132和0.002 N ₂ O‐N kg ^-1干燥土壤h ^-1。一氧化二氮的产生和地下土壤的还原保持较低的速率，并且在深度和水文区域之间显示出很小的变化。我们的结果表明N个_2代ö动力学是由深度的影响，主要是通过活性有机碳（C）和微生物量C，主要是通过土壤NO通过水文区的影响₃ ^-含量。N ₂的空间分布来自反硝化作用的沿水文梯度的O通量可能归因于N ₂ O产生的差异和表层土壤的减少。