The influence of soil pH changes by liming on denitrification and denitrifier gene abundance under different biogeochemical conditions by amending two contrasting soils with water, cattle urine (600 mg N kg−1 soil) and urine + dicyandiamide (DCD) (10 mg kg−1 soil) and incubating at 10 °C and 15 °C was evaluated. Liming increased N2O emission, denitrification rate and denitrifier gene abundance in both soils. The increase in N2O and denitrification with liming was higher in fluvial soil (24% increase in N2O and 22% increase in denitrification) than in allophanic soil (16% in N2O and 19% increase in denitrification). There was more N2O coming from urine applied to limed soil than that from urine to un-limed soil. Addition of DCD with urine reduced both N2O emission and denitrification; the reduction was greater in limed soil than in un-limed soil. Results of quantitative polymerase chain reaction (qPCR) of bacterial denitrifier genes (nirS, nirK and nosZ genes) indicate that liming-induced soil pH changes increased denitrifier gene abundance and caused more complete bacterial denitrification in urine-amended soils. These results suggest that liming grazed pasture soils induces complete denitrification, which may mitigate N2O emissions.

中文翻译：

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石灰诱导的 pH 值变化对施肥牛尿中一氧化二氮排放、nirS、nirK 和 nosZ 基因丰度的影响

通过用水修改两种对比土壤，牛尿（600 mg N kg−1 土壤）和尿液+双氰胺（DCD）（10 mg kg−1），石灰对反硝化和反硝化基因丰度的影响在不同生物地球化学条件下土壤）并在 10 °C 和 15 °C 下进行评估。石灰增加了两种土壤中的 N2O 排放、反硝化率和反硝化基因丰度。河流土壤中 N2O 和反硝化作用的增加在河流土壤中（N2O 增加 24%，反硝化作用增加 22%）高于脱氮土壤（N2O 增加 16%，反硝化作用增加 19%）。施用于石灰土壤的尿液中的 N2O 比施用于未施石灰土壤的尿液中的 N2O 多。在尿液中加入 DCD 可减少 N2O 排放和反硝化作用；石灰土壤中的减少量大于未石灰土壤。细菌反硝化基因（nirS、nirK 和 nosZ 基因）的定量聚合酶链反应 (qPCR) 结果表明，石灰诱导的土壤 pH 变化增加了反硝化基因丰度，并导致尿液修正土壤中的细菌反硝化更完全。这些结果表明，石灰放牧的牧场土壤会引起完全反硝化，这可能会减少 N2O 的排放。