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KLIR: A Model for Calculating Greenhouse Gas Emissions from Dairy Farms

Dairy farms are responsible for a significant proportion of greenhouse gases from agriculture. In order to quantify emissions at farm level and identify suitable emissions reduction measures, HAFL researchers developed a model for calculating greenhouse gas emissions from dairy farms.

Agriculture is responsible for one seventh of Switzerland’s greenhouse gas emissions, and dairy farms account for more than half of that share. Policymakers have therefore been calling for emissions reduction measures. To test the effectiveness of such measures for the specific conditions of roughage-based dairy production, it is necessary to be able to quantify emissions at the individual farm level.

To this end, the School of Agricultural, Forest and Food Sciences at the Bern University of Applied Sciences (BFH-HAFL) developed the farm-level greenhouse gas emissions model KLIR as part of its project on climate-friendly and resource-efficient dairy production and tested it on 46 dairy farms. The project was implemented by dairy supplier Aaremilch AG and funded by Nestlé and the Swiss Federal Office for Agriculture (FOAG) under the Ordinance on Promoting Quality and Sustainability in the Agriculture and Food sector (QuNaV). Based on internationally recognised calculation methods specifically adapted to Switzerland, the KLIR model (available as an online application and Excel tool) calculates the annual greenhouse gas emissions (expressed in CO2 equivalents) of a dairy farm and simulates the effects of emissions reduction measures. Given that many potential reduction measures in the literature focus on ruminant feeding, the KLIR model focuses specifically on the farms’ individual feed rations.

Contribution of relevant emission sources (mean and standard deviation) to the greenhouse gas emissions of the 46 dairy farms studied for the KLIR model.

KLIR has shown that methane emissions from enteric fermentation (breakdown of carbohydrates by microorganisms in the rumen of the cows) contribute approximately 56% to the total greenhouse gas emissions from dairy farming. Manure storage accounts for about 23% of total emissions and feed production (feed produced on-farm and purchased feed) accounts for 20%.

System boundaries of the KLIR model

In emission models, the boundaries of observation (system boundaries) must be defined. In KLIR the dairy farm is defined as the system boundary, while, as is common for life-cycle analyses, emissions from intermediate inputs (such as feed and fertiliser production) were also taken into account. Not included in the calculations were, for example, the fattening of surplus youngstock, emissions from the construction of farm buildings, and the agricultural soil carbon balance. At 1.01 kg CO2 equivalents per kg of milk standardised for fat and protein content (ECM, energy corrected milk), the greenhouse gas emissions calculated using the KLIR model are lower than previously estimated for Switzerland. In an international comparison of highly specialised milk production systems, the farms investigated here fall into the medium range.

Allocation of emissions to milk and meat

Dairy farming is always associated with beef production, as surplus youngstock is fattened for beef and spent dairy cows are culled. Different methods were tested for the allocation of emissions to milk and meat respectively. By allocating emissions to milk as the main product and meat as a co-product, the emissions per kg ECM decrease significantly to 0.75 – 0.77 kgCO2 equivalents.

Conclusions

  • The KLIR model allows for plausible, mechanistic farm-level greenhouse gas modelling under Swiss conditions and in keeping with international standards.
  • Methane emissions from enteric fermentation account for the bulk of greenhouse gas emissions from dairy farming.
  • The modelled emissions are highly sensitive to the method of allocating the emissions to milk and its co-product meat respectively.

Scientific article

KLIR: A Model for Calculating Greenhouse Gas Emissions from Dairy Farms

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