the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 12 Aug 2026
Warming-induced agricultural nitrous oxide emissions can offset mitigation benefits of fertiliser management
Abstract. Agriculture is the dominant source of anthropogenic nitrous oxide (N2O), a potent greenhouse gas with a high global warming potential. In Switzerland, substantial changes in fertiliser use alongside climatic conditions have occurred over the past four decades, yet the relative contributions of management practices versus environmental change to long-term N2O emission trends remain incompletely understood. Here, we applied the biogeochemical model DayCent at 1 km resolution across Switzerland, integrating spatially explicit datasets on climate, soil properties and agricultural management, to quantify N2O emissions for the period 1981–2020 from croplands and grasslands and attribute emission changes to management versus climate drivers. Simulated national N2O emissions from agricultural soils declined by roughly 5 % from 4.0 to 3.8 kt N yr⁻¹ between the 1980s and 2010s, primarily due to a 25 % reduction in N fertiliser use. Our attribution simulations suggested that under real climate conditions, such a decrease in fertiliser N inputs (–25 %) over the period studied lowered emissions by 15.2 % in croplands and by 12.0 % in grasslands (including permanent meadows and pastures, and high alpine summer pastures). However, compared to a control scenario (in the absence of climate change), rising temperatures over the past 40 years offset these gains, increasing emissions by 5.7 % in croplands and 13.6 % in grasslands. These results show that warming-induced N2O emissions partially negate mitigation from improved fertiliser management, highlighting the need for integrated agricultural N2O mitigation strategies that are resilient to future warming.
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Status: open (until 01 Oct 2026)
- RC1: 'Comment on egusphere-2026-4445', Anonymous Referee #1, 03 Sep 2026 reply
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Dear Editor,
The manuscript, “Warming-induced agricultural nitrous oxide emissions can offset mitigation benefits of fertiliser management” by Jiang et al., is interesting and addresses a scientifically important question. However, I would recommend major revisions before acceptance.
The topic is timely and important. The manuscript addresses a strong research question with potentially important implications for agricultural climate mitigation. The combination of high-resolution, process-based explicit modelling with a valuable national-scale dataset/model framework is a major strength. The manuscript is also transparent about several limitations of the modelling framework.
The scientific results are presented clearly and concisely.
However, I have substantial concerns regarding the representation of agricultural management dates and fertiliser timing, land-use change, and biological nitrogen fixation (BNF) in the scenario study.
Major comments
1. Representation of management dates and fertiliser timing
The authors state that they use static/fixed management calendars rather than dynamically varying management dates between years. For a 40-year climate-change analysis, this could be important because warming may affect planting and harvest dates, growing-season duration, mowing and grazing dates, and plant N demand, among other processes.
If fertilisation occurs on a fixed calendar date despite a progressively earlier growing season, the model may create an artificial mismatch between N fertilisation and plant N demand. This mismatch could itself affect simulated N₂O emissions. Similarly, keeping mowing dates fixed could affect plant residue inputs and SOM mineralisation.
The conclusion that warming increases N₂O emissions may therefore partly reflect the interaction between warming and fixed management schedules. I suggest that the authors quantify the effect of climate-responsive management dates for fertilisation, mowing, and other relevant management activities, in order to demonstrate whether the main conclusions remain robust when management responds to climate change.
2. Land-use change and fertiliser inputs (Lines 200–201)
The authors state that “total fertiliser inputs also depend on land use areas which changed land use over the past 40 years, especially for croplands.” How have the authors addressed this issue? Were land-use areas kept static, as in Figure S1?
If land-use areas were kept static, please quantify the impact of this assumption on the study outcomes. In particular, how does it affect the partitioning of national total fertiliser inputs among different crops?
3. Biological nitrogen fixation (Lines 440–441)
The authors state that “BNF became an increasingly important N input in unfertilised grasslands, potentially contributing to an increase in modelled background emissions under warming conditions.” Is temporal variation in the area undergoing BNF included in the DayCent simulations? If so, please show the variation in BNF area over time and report the simulated contribution of BNF to total N inputs for both cropland and grassland. This would help determine whether the increasing grassland background N₂O emissions shown in Fig. 1b are driven, at least partly, by changes in BNF.
4. Synthetic versus organic fertiliser N inputs
I think Fig. 1c and the description of fertiliser N inputs would benefit from separating synthetic and organic N inputs for both cropland and grassland. I suggest showing separate time series for synthetic and organic fertiliser N inputs for cropland and grassland, for example by adding these results to Fig. S6. This would clarify whether the reported decline in fertiliser N inputs is primarily attributable to changes in synthetic fertiliser, manure/organic fertiliser, or both.
5. Suggested modification of the title
I suggest modifying the title to: “Climate warming-induced agricultural nitrous oxide emissions can offset mitigation benefits of fertiliser reduction”
This would clarify that the study specifically concerns climate warming and reductions in fertiliser N inputs.
Minor comments
6. Please clarify in the caption whether “Fertilizer N inputs” in Fig. 1c includes both synthetic and organic fertilisers, as well as manure deposited during grazing.
7. How is fertilisation distributed among crops in the model setup? Are synthetic and organic fertilisation data available separately for individual crops? Please specify this in the Methods section.
8. Please specify whether the nofert scenario also sets grazing-derived N inputs to zero. This could be clarified in the text, for example around Lines 186–189.