Conversion from synthetic nitrogen (N) fertilizer to organic manure has been well documented to effectively mitigate nitric oxide (NO) emissions in the current year or growing season. However, a clear understanding of NO emissions following long-term manure substitution is lacking. We hypothesize that soil conditions (particularly the accumulation of organic matter) following long-term manure substitution may stimulate NO emissions by providing more N substrates under favorable conditions. The primary aims of this study were to (1) quantify the long-term effects of manure substitution on NO emissions, and (2) identify the major regulating factors that contribute to the variations. Field measurements were conducted under summer maize-winter wheat rotations in a long-term fertilization experiment (since 1990) over three experimental years (from June 2016 to May 2019). The three treatments included an unfertilized control (CK), full synthetic urea in both crop seasons (NPK), and full synthetic urea in the maize season with 70% urea substituted by dairy manure in the winter wheat season (NPKM). Annual NO emissions varied from 0.10 to 0.22 kg N ha⁻¹ and from 0.32 to 1.53 kg N ha⁻¹ in CK and the fertilized treatments, respectively. We attributed the variations in annual NO emissions from the fertilized treatments to mean soil temperature by fitting a significant linear regression between the two variables (r² = 0.681, p = 0.008). Seasonal NO emissions from NPKM treatment were lower (range, 2–66%, not always significant) and larger (range, 115–294%, not always significant) than those from NPK during the winter wheat and maize seasons, respectively. Annual NO emissions from NPKM treatment were 78% larger (range, 44–112%, not always significant) than those from NPK across the experimental years. Overall, this three-year field measurement revealed that cumulative NO emissions from NPKM treatment were significantly (p = 0.038) larger than those from NPK (2.73 versus 1.53 kg N ha⁻¹). We concluded that long-term manure substitution for synthetic fertilizer in the winter wheat seasons did not mitigate, but rather stimulated cumulative NO emissions.

从合成氮 (N) 肥料到有机肥料的转化已得到充分证明，可有效减少当年或生长季节的一氧化氮 (NO) 排放。然而，对长期粪便替代后的 NO 排放缺乏清晰的认识。我们假设长期粪便替代后的土壤条件（特别是有机质的积累）可能会通过在有利条件下提供更多的 N 底物来刺激 N2O 排放。本研究的主要目的是 (1) 量化粪肥替代对 NO 排放的长期影响，以及 (2) 确定导致变化的主要调节因素。在三个实验年（2016 年 6 月至 2019 年 5 月）的长期施肥实验（自 1990 年以来）中，在夏玉米-冬小麦轮作下进行了田间测量。这三种处理包括未施肥的对照（CK）、两个作物季节的全合成尿素（NPK）和玉米季节的全合成尿素，在冬小麦季节用70%的尿素替代乳肥（NPKM）。年 NO 排放量从 0.10 到 0.22 kg N ha^-1和 0.32 至 1.53 kg N ha ^-1在 CK 和施肥处理中，分别。我们通过拟合两个变量之间的显着线性回归（r ²= 0.681，p = 0.008）。在冬小麦和玉米季节，NPKM 处理的季节性 N2O 排放分别低于（范围，2-66%，并不总是显着）和更大（范围，115-294%，并不总是显着）。在整个实验年份，NPKM 处理的年 NO 排放量比 NPK 的排放量大 78%（范围为 44-112%，并不总是显着）。总体而言，这项为期三年的现场测量显示，NPKM 处理的累积 NO 排放量显着 (p = 0.038) 大于 NPK 的累积排放量（2.73 对 1.53 kg N ha ^-1）。我们得出的结论是，在冬小麦季节长期用粪肥替代合成肥料并没有减轻，而是刺激了累积的 NO 排放。