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Nitrous oxide emissions from winter oilseed rape cultivation.
- Source :
-
Agriculture, Ecosystems & Environment . Nov2017, Vol. 249, p57-69. 13p. - Publication Year :
- 2017
-
Abstract
- Winter oilseed rape ( Brassica napus L., WOSR) is the major oil crop cultivated in Europe. Rapeseed oil is predominantly used for production of biodiesel. The framework of the European Renewable Energy Directive requires that use of biofuels achieves GHG savings of at least 50% compared to use of fossil fuel starting in 2018. However, N 2 O field emissions are estimated using emission factors that are not specific for the crop and associated with strong uncertainty. N 2 O field emissions are controlled by N fertilization and dominate the GHG balance of WOSR cropping due to the high global warming potential of N 2 O. Thus, field experiments were conducted to increase the data basis and subsequently derive a new WOSR-specific emission factor. N 2 O emissions and crop yields were monitored for three years over a range of N fertilization intensities at five study sites representative of German WOSR production. N 2 O fluxes exhibited the typical high spatial and temporal variability in dependence on soil texture, weather and nitrogen availability. The annual N 2 O emissions ranged between 0.24 kg and 5.48 kg N 2 O-N ha −1 a −1 . N fertilization increased N 2 O emissions, particularly with the highest N treatment (240 kg N ha −1 ). Oil yield increased up to a fertilizer amount of 120 kg N ha −1 , higher N-doses increased grain yield but decreased oil concentrations in the seeds. Consequently oil yield remained constant at higher N fertilization. Since, yield-related emission also increased exponentially with N surpluses, there is potential for reduction of the N fertilizer rate, which offers perspectives for the mitigation of GHG emissions. Our measurements double the published data basis of annual N 2 O flux measurements in WOSR. Based on this extended dataset we modeled the relationship between N 2 O emissions and fertilizer N input using an exponential model. The corresponding new N 2 O emission factor was 0.6% of applied fertilizer N for a common N fertilizer amount under best management practice in WOSR production (200 kg N ha −1 a −1 ). This factor is substantially lower than the linear IPCC Tier 1 factor (EF1) of 1.0% and other models that have been proposed. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 01678809
- Volume :
- 249
- Database :
- Academic Search Index
- Journal :
- Agriculture, Ecosystems & Environment
- Publication Type :
- Academic Journal
- Accession number :
- 125115470
- Full Text :
- https://doi.org/10.1016/j.agee.2017.07.039