Soil pH is generally considered a master variable, controlling a wide range of physical, chemical and biological properties, including a significant effect on microbial processes responsible for production and consumption of nitrous oxide (N₂O), a potent greenhouse gas. Evidence of this pH impact on microbial denitrification mainly stems from observations in controlled laboratory experiments, while the results from field studies are mainly short-term, more variable and circumstantial. Soil pH is also one of the main factors controlling the availability of soil phosphorous (P), which has been also linked with N₂O emissions. Here, we utilised an existing intensive grassland liming and P trial to investigate the effect of longer-term lime and P management and their interaction on N₂O emissions and grassland productivity. The treatment plots were subject to different liming and P fertilisation strategies over 8 years and had a wide gradient of soil pH (5.1–6.9) and extractable P (2.3–8.3 mg kg⁻¹). All plots received a total of 300 kg ha⁻¹ of fertiliser nitrogen (N), applied in 8 splits across the growing season. N₂O emissions, soil mineral N and grass yields were measured over 12-month period. We found a negative linear relationship between soil pH and cumulative N₂O emissions, with a decrease in N₂O emissions up to 39 % from limed plots compared to the unlimed control. The same effect was observed in relation to N₂O emission factors and yield-scaled N₂O emissions. Extractable soil P content had positive effect on yields, but no effect of P or P and pH interaction was observed in terms of direct N₂O emissions or yield-scaled N₂O emissions. We estimated that the increase in soil pH of grasslands in Ireland over the last 12 years potentially reduced national N₂O emissions by 95 Gg CO₂-eq yr⁻¹, with potential for a further reduction by up to 254 Gg CO₂-eq yr⁻¹ if all the remaining acidic soils are brought up to optimal pH.

通常将土壤pH值视为主要变量，控制着广泛的物理，化学和生物学特性，包括对微生物过程的重大影响，该过程负责生产和消耗强效的一氧化二氮（N ₂ O）。pH值对微生物反硝化影响的证据主要来自受控实验室实验的观察结果，而现场研究的结果则主要是短期的，变化较大的和环境的。土壤pH值也是控制土壤磷（P）有效性的主要因素之一，磷也与N ₂ O排放有关。在这里，我们利用现有的集约化草原石灰和磷肥试验来研究长期石灰和磷肥管理及其相互作用对氮素的影响。₂ O排放和草地生产力。处理地块在8年内经历了不同的施肥和施磷策略，土壤pH值（5.1–6.9）和可提取的P（2.3–8.3 mg kg ^-1）的梯度很大。所有地块在生长季节共分8次施用了总计300 kg ha ^-1的肥料氮（N）。在12个月内测量了N ₂ O排放，土壤矿质N和草的产量。我们发现土壤pH值与累积N ₂ O排放量之间呈负线性关系，与未施肥的对照相比，石灰田的N ₂ O排放量减少了39％。关于N ₂观察到相同的效果O排放因子和按比例缩放的N ₂ O排放。可提取的土壤P含量对产量有积极影响，但在直接N ₂ O排放或产量定额N ₂ O排放方面，未观察到P或P和pH相互作用。我们估计，在过去的12年中，爱尔兰草原土壤pH的升高可能使全国N ₂ O排放量减少95 Gg CO ₂ -eq yr ^-1，并有可能进一步减少254 Gg CO ₂ -eq如果所有剩余的酸性土壤均达到最佳pH，则yr ^-1。