EGU22-7562, updated on 20 May 2022
https://doi.org/10.5194/egusphere-egu22-7562
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Fertilizer type effect on nitrous oxide (N2O) emissions in a Swedish long-term field experiment

Rong Lang1, Muhammad Shahbaz2, Katharina H. E. Meurer3, Gunnar Börjesson3, and Thomas Kätterer1
Rong Lang et al.
  • 1Swedish University of Agricultural Sciences, Department of Ecology, Box 7044, 750 07 Uppsala, Sweden
  • 2Lund University, Centre for Environmental and Climate Science, 223 62 Lund, Sweden
  • 3Swedish University of Agricultural Sciences, Department of Soil and Environment, Box 7014, 750 07 Uppsala, Sweden

Fertilization in agriculture contributes substantially to an increase in nitrous oxide (N2O) emission to the atmosphere, optimizing fertilization is one of the mitigation strategies to reduce greenhouse gas (GHG) emissions while maintaining high crop production. In the Ultuna long-term frame trial, treatments including organic amendments and different types of mineral nitrogen fertilizers have been applied since1956 to quantify their effects on crop production, soil carbon and nitrogen cycling. However, the understanding of their effect on GHG emissions from soils is still quite limited. For this reason, we chose four treatments, including no fertilizer (control), calcium nitrate, ammonium sulfate and calcium cyanamide to study the mineral fertilizer type effect on N2O emissions and the plant-soil-microbe interactions over one crop growth period.  

N2O fluxes in the growing season were continuously measured from the 1 June to 15 Oct in 2019, using a Picarro N2O analyzer and 12 automated eosAC chambers. The frame trial has a randomized complete block design and we chose treatments in three blocks as replicates. In each plot, we placed two sensors to measure soil moisture and temperature. A mixed model was used to test the effect of fertilizer type and measurement date, with consideration of auto-correlations in the repeated measurements. Soil moisture and temperature were added to the regression model to quantify the controlling factors of the N2O fluxes. Measurement date was treated as a continuous variable.

The effects of both treatment and measurement date were statistically significant. Despite its higher pH values, the calcium nitrate  treatment emitted significantly more N2O than the control: 90.8±23.4 compared with 32.2±8.3 nmol m-2 s-1, respectively. The treatment with calcium cyanamide had pH-values and total N similar to those in the calcium nitrate treatment, but N2O emissions were 72% lower (25.0±6.5 nmol m-2 s-1) than the emission in the calcium nitrate treatment. Due to low soil pH, N2O fluxes were constantly low in the ammonium sulfate treatment, with an average emission of 24.3±6.3 nmol m-2 s-1. The temporal dynamics differed a lot between treatments, as suggested by significant interaction between treatment and measurement date. Further, regression with soil moisture and temperature showed that both variables contributed to explaining the temporal variation of N2O fluxes mainly in the control and calcium nitrate treatments. In contrast, N2O fluxes in the calcium cyanamide treatment were low throughout the growing season, suggesting that it effectively suppressed not only nitrification in the early growing season, but also the denitrification process in the late growing season.

Considering the highest maize biomass and lowest N2O emissions the calcium cyanamide treatment, using calcium cyanamide as nitrogen fertilizer has a great potential to reduce N2O emissions from agricultural soils without compromising crop production.  

How to cite: Lang, R., Shahbaz, M., Meurer, K. H. E., Börjesson, G., and Kätterer, T.: Fertilizer type effect on nitrous oxide (N2O) emissions in a Swedish long-term field experiment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7562, https://doi.org/10.5194/egusphere-egu22-7562, 2022.

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