We are grateful to Reviewer 1 for their constructive comments. Please find below our responses.  

1. L167, please correct information around analytical uncertainties-one number for N₂O and one for CH₄

Thank you for highlighting a potential misinterpretation around the analytical uncertainty of N₂O and CH₄. I have clarified this in text. Please see below.

“The analytical uncertainty in flux methodology was calculated to be ±0.05 nmol m⁻² s⁻¹ for N₂O fluxes and ±0.58 nmol m⁻² s⁻¹ for CH₄ fluxes (Cowan et al., 2025).”

1. Some of the highest observed N₂O fluxes occurred in July and August 2021, prior to the start of NH₃ I cannot find any narrative or explanation for this in the discussion section. Do you have any idea why this happened? What were the environmental conditions on the experimental site during this time?

Yes indeed, the period of the highest observed N₂O fluxes coincided with a period of warm and wet conditions, which supports the dual temperature – moisture threshold suggested by this study. I have added this in lines 461 to 466.

“This is consistent with the findings of this study which suggest that environmental factors had a more pronounced effect on N₂O fluxes relative to the experimental treatment (gaseous NH₃ addition). For instance, the highest in-situ N₂O fluxes were observed between June and August 2021 (Fig. 2) which corresponded to a relatively warm (soil temperature > 12 °C) and wet period (VWC > 20 %) (Fig. S4). In contrast, N₂O fluxes during June to August 2022 were relatively low (median flux < 0.05 nmol N₂O m⁻² s⁻¹), which could potentially be explained by a period of drought that summer (VWC < 15%). These findings suggest a dual temperature-moisture threshold which could be controlling soil N₂O fluxes.”

1. In L507-508 you say that observations in this study are consistent with the IPCC EF for non-agricultural soils. However, there is no mention anywhere in text what an indicative EF from the current experiment could be. Could you stipulate based on data from  the control and impact chambers?

N₂O fluxes have been calculated as a proportion of NH₃ dry deposition, which corresponded to 0.38% from control areas and 0.05% from impact areas (please see Table 1 below). According to the IPCC methodology fluxes from control areas are subtracted from fluxes from impact areas. In this case, this would result in a negative value. Even though fluxes of N₂O were low throughout the study period (both in-situ and ex-situ), there was no evidence of uptake of N₂O by the soil and previous work by Cowan et al.(2014) have suggested that negative N₂O fluxes are often a methodological artefact. Presenting a negative emission factor could be misleading to the reader, which is why we have been reluctant to include these calculations in the manuscript.

Table 1 Fluxes of N₂O as a proportion of NH₃ dry deposition.

We are grateful to the Reviewer for their constructive comments. Please find our responses below. 

1. Please clarify in the methods why the addition of N In the lab is done with both NH4+ and NH4NO3, instead of opting to only apply NH4+, which better simulates the addition of NH₃ as it was done in the field. This comes clear in the results, in order to check the effects of both reduced and oxidized N forms, but not before.

A clarification has been added in the methods section (line 186) as to why N was added both in the form of NH₄⁺ and NH₄NO₃.

“N was applied in the form of either NH₄⁺ in aqueous solution (Cowan et al., 2024) or NH₄NO₃ in order to study the effects of reduced and oxidised N forms.”

1. In Fig 2 it could be indicated that the NH₃ release system was not working in July 22, as the previous 2 months N₂O fluxes were high, and higher in the impact areas.

Fig.2 and its caption were  edited by adding an asterisk to indicate the temporary issue with the NH₃ release system in July 2022.

Figure 2 Fluxes of N₂O over the duration of the experiment. Fluxes measured from control area (blue) and area where the impact of NH₃ deposition was expected (orange) are shown. The horizontal dashed lines mark the minimum detectable flux. The vertical line denotes the start of the NH₃ release. An asterisk (*) in July 2022 indicates that the NH₃ release system was inactive for most of the month due to technical issues.

1. Is there a reason in the field for the higher fluxes, before the start of the application of the NH₃ treatment, in the control areas? Fluxes reached very high levels in June-July 2021, which did not happen again. Can meteorologiocal conditions (temperture or soil moisture) at that time help explaining these extremely large fluxes?

Yes indeed, the period of the highest observed N₂O fluxes coincided with a period of warm and wet conditions, which supports the dual temperature – moisture threshold suggested by this study. I have added this in lines 461 to 466. This was also addressed as part of Reviewer 1, comment #2.

“This is consistent with the findings of this study which suggest that environmental factors had a more pronounced effect on N₂O fluxes relative to the experimental treatment (gaseous NH₃ addition). For instance, the highest in-situ N₂O fluxes were observed between June and August 2021 (Fig. 2) which corresponded to a relatively warm (soil temperature > 12 °C) and wet period (VWC > 20 %) (Fig. S4). In contrast, N₂O fluxes during June to August 2022 were relatively low (median flux < 0.05 nmol N₂O m⁻² s⁻¹), which could potentially be explained by a period of drought that summer (VWC < 15%). These findings suggest a dual temperature-moisture threshold which could be controlling soil N₂O fluxes.”

1. L384-385 and Table 2: I do not think the abbreviation AN was explained before, please clarify that this stands for NH4NO3.

Table 2 was edited by explaining the meaning of the AN abbreviation. Please see below.

“Nitrogen was applied either in the form of ammonium (NH₄⁺) or ammonium nitrate (AN, NH₄NO₃).”