Experimental determination of emission factors and the greenhouse gas budget of grazing systems in Switzerland: Final Report Extended Summary (Project on behalf of the Swiss Federal Office for the Environment FOEN).
The present study analyzed the greenhouse gas flux measurements of a grazed pasture system for dairy cows in western Switzerland over five years. Based on the evaluation and the corresponding uncertainties the pasture has to be considered as near carbon-neutral and as a small source for CH4. However, the pasture was found to be a considerable and significant source of N2O attributable both to grazing excreta and to fertilizer spreading. The developed partitioning procedure allowed the determination of excreta-related and fertilizer-related emission factors. While the fertilizer-related emission factor was on average close to the corresponding IPCC default value, the excreta-related factor was significantly lower than the presently used default value of 2%. It could also be shown that there is a clear difference in the individual emission factors for urine and dung patches on the pasture. For the development of country-specific emission factors for Switzerland, a combined use of process-based modelling and experimental results is recommended.
