EGU22-3066, updated on 27 Mar 2022
https://doi.org/10.5194/egusphere-egu22-3066
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

High off-season nitrous oxide emissions negate potential soil C-gain from cover crops in boreal cereal cropping

Peter Dörsch1, Ievina Sturite2, and Sigrid Trier Kjær3
Peter Dörsch et al.
  • 1Norwegian University of Life Sciences, Norway (peter.doersch@nmbu.no), Postbox 5003, 1432 Ås, Norway
  • 2The Norwegian Institute for Bioeconomy, Postbox 115, NO, 1431, Ås, Norway
  • 3Norwegian University of Life Sciences, Norway and Department of Environmental Systems Science, ETH Zurich, Universitätstrasse 16, 8092 Zürich, Switzerland

Enhancing carbon storage in managed soils through increased use of cover and catch crops in cereal cropping is at the heart of a carbon-negative agriculture. However, increased C storage by additional biomass production has a nitrogen cost, both in form of increased N fertilizer use and by potentially increasing nitrous oxide (N2O) emissions when cover crops decay. Frost-sensitive, N-rich aboveground biomass may be a particular problem during wintertime, as it may fuel off season N2O emissions during freezing-thawing cycles, which have been shown to dominate the annual N2O budget of many temperate and boreal sites. Here we report growing season and winter N2O emissions in a plot experiment in SE Norway, testing a barley production system with seven different catch and cover crops (perennial and Italian ryegrass, oilseed radish, summer and winter vetch, phacelia​ and an herb mixture) against a control without cover crops. Cover crops where either undersown in spring or established after harvesting barley. While ryegrass undersown to barley marginally reduced N2O emissions during the growing season, freeze-thaw cycles in winter resulted in significantly larger N2O emissions in treatments with N-rich cover crops (oilseed reddish, vetch) and Italian ryegrass. N2O budgets will be presented relative to aboveground yield and quality of cover crops and compared to potential souil organic carbon gains. 

How to cite: Dörsch, P., Sturite, I., and Trier Kjær, S.: High off-season nitrous oxide emissions negate potential soil C-gain from cover crops in boreal cereal cropping, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3066, https://doi.org/10.5194/egusphere-egu22-3066, 2022.

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