Assign allocation shares to emission variables by commodity

Expands commodity-level allocation shares across emission sources and applies predefined allocation rules for excluded emission sources.

Usage

assign_allocation_shares(
  allocation_herd_long,
  emissions_vars,
  commodities,
  non_allocated_emission_sources,
  commodity_col,
  allocation_col
)

Arguments

allocation_herd_long: Long-format data.table containing herd-level emissions and allocation information. Each row represents an emission source–commodity combination or an unallocated emission source prior to allocation.
emissions_vars: Character. Names of emission variables to which allocation should be applied (e.g., "ch4_enteric","ch4_manure_pasture","ch4_manure_burned","ch4_manure_other", "n2o_manure_pasture_direct","n2o_manure_burned_direct","n2o_manure_other_direct", "n2o_manure_burned_indirect","n2o_manure_pasture_indirect","n2o_manure_other_indirect", "co2_ration_fertilizer", "co2_ration_pesticides", "co2_ration_crop_activities", "co2_ration_luc_nopeat", "co2_ration_luc_peat", "n2o_ration_fertilizer", "n2o_ration_manure_applied", "n2o_ration_crop_residues", "ch4_ration_rice").
commodities: Character. List of commodity categories to which emissions may be allocated. For example: c("None","Milk","Meat","Fibre","Work","Eggs").
non_allocated_emission_sources: Character. Emission variables that should not be allocated across commodities, even if they appear in emissions_vars (e.g., "ch4_manure_pasture", "ch4_manure_burned").
commodity_col: Character. Name of the column in allocation_herd_long identifying the commodity category.
allocation_col: Character. Name of the column in allocation_herd_long containing the allocation share to be applied.

Value

A data.table equal to allocation_herd_long expanded over all emissions_vars, with enforced allocation rules:

Non-allocated emission sources: allocation_col = 1 when commodity_col == "None", else 0.
Allocated emission sources: allocation_col = 0 when commodity_col == "None" (others unchanged).

Details

The function assigns commodity allocation shares to emission sources while also allowing for the implementation of specific allocation rules. Emission sources listed in non_allocated_emission_sources (e.g., emissions from manure burned as fuel or manure deposited on pasture) are treated as not attributable to livestock commodities under the chosen goal and scope. Consequently, these emissions are allocated entirely to the residual commodity category "None" and are not distributed across milk, meat, fibre, work, or egg outputs.

The following methodological rules apply to emission sources listed in non_allocated_emission_sources:

Manure burned for fuel — Emissions are considered outside the life cycle assessment system boundaries under the defined goal and scope and are therefore not attributed to livestock commodities. A cut-off approach is applied, consistent with the IDF (2022) standard and LEAP guidelines (LEAP 2016a, 2016b, 2016c).
Manure deposited on pastures — Emissions are not allocated to livestock commodities in order to avoid double counting. When upstream feed production is included in the inventory, emission factors of feed items already account for this source.

This function is part of the run_allocation_module().

References

IDF. (2022). The IDF Global Carbon Footprint Standard for the Dairy Sector. Bulletin of the IDF No. 520/2022. International Dairy Federation, Brussels.

FAO. (2016a). Environmental performance of large ruminant supply chains: Guidelines for assessment. Livestock Environmental Assessment and Performance (LEAP) Partnership. FAO, Rome, Italy.

FAO. (2016b). Greenhouse gas emissions and fossil energy use from small ruminant supply chains: Guidelines for assessment. Livestock Environmental Assessment and Performance (LEAP) Partnership. FAO, Rome, Italy.