Simulated hot spots and hot moments of soil N2O Emissions from agriculture across land use, management, and climate in central europe

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200212150

Agricultural ecosystems are the largest source for soil nitrous oxide (N2O) emissions and understanding their spatial and temporal variability, particularly in agricultural ecosystems, is crucial for effective climate change mitigation measures, aligning with the targets established by the European Green Deal. Model simulations are an important tool to quantify N2O emissions over several years across land use, agricultural management, and climate at local, regional, or global scales. Here, we systematically evaluate simulated soil N2O emissions from six different regions in Austria representing main cultivation areas located in two different European biogeographical zones (alpine and continental) with the process-based ecosystem model LandscapeDNDC. We present region-specific daily and annual N2O emissions from arable and grassland soils over a ten-year period considering more than 70% of land area and crops grown in the study regions. To identify hot moments of N2O emissions, we defined a threshold of extreme N2O peaks as daily emissions by the equation: Peak > 3rd Quantile + 3 * (3rd Quantile – 1st Quantile). The simulations show that specific crops and management activities have profound effects on daily N2O emissions. The share of N2O emitted as peak emissions ranges from 12% to 79% of total annual emissions. Overall, per hectare, the simulated mean annual N2O emissions are 69% lower from arable soils than from intensively managed grasslands, however, peak N2O emissions are higher and more frequent in the arable system. N2O peak events are mainly occurring between April and October from arable as well as grassland soils. N2O hotspots correlate to high soil organic carbon content or nitrogen fertilizer application rates, whereby the dominant controlling factors varied between regions and land use. The modelling results demonstrate potential environmental impacts and propose strategies for climate- and eco- friendly farming practices.
Keywords: N2O emissions, agriculture soil, hotspots, hot moments, landscape DNDC