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Allocate grazing land forward to livestock products.

Source: R/footprint_grazing.R
allocate_grazing_to_products.Rd

Push grazing land forward along the feed chain instead of tracing it backward through a Leontief inverse. Grass is not traded, so the multi-regional input-output footprint leaks the grazing land that meat and dairy consumption actually drives (the feed-conversion columns make the system non-productive). This function hands every tonne of grazing land forward in two mass-conserving steps:

  1. pool each country's grazing land and split it across the grazing animals that fed there, in proportion to their forage intake;

  2. split each animal's share across its output products in proportion to production mass, landing the land on the meat and milk items that are actually traded.

The result is a direct-land extension keyed by livestock output item, ready to route to consumers with compute_footprint_balance(). Because each step redistributes a total without creating or destroying it, the country-level land total is conserved whenever an animal fed and produced an output there.

Usage

allocate_grazing_to_products(
  grass_land,
  grazer_intake,
  livestock_production,
  products = c("all", "meat_milk")
)

Arguments

grass_land

Tibble with year, area_code and value (grazing land, e.g. hectares). Multiple rows per country (for example one per grass item) are pooled.

grazer_intake

Tibble with year, area_code, live_anim_code and value (the intake by which to split the land across animals), as from get_feed_intake(). Using grazer forage intake (grass plus roughage residues) rather than the "grass" feed type alone keeps extensive-grazing countries, whose forage the feed model classes as residues, from dropping out.

livestock_production

Tibble with year, area_code, live_anim_code, item_cbs_code and value (output production, tonnes).

products

Which output items absorb the land. "all" (default) spreads it across every livestock output by mass; "meat_milk" restricts it to meat and dairy items, so all grazing land lands on meat and dairy consumers per the forward-allocation goal.

Value

A tibble with year, area_code, item_cbs_code (a livestock output item), value (grazing land allocated to it) and method_allocation (the chosen products).

Examples

grass_land <- tibble::tibble(
  year = 2010L, area_code = 1L, value = 100
)
grazer_intake <- tibble::tibble(
  year = 2010L,
  area_code = 1L,
  live_anim_code = c(960L, 976L),
  value = c(75, 25)
)
livestock_production <- tibble::tibble(
  year = 2010L,
  area_code = 1L,
  live_anim_code = c(960L, 960L, 976L),
  item_cbs_code = c(2848L, 2731L, 2732L),
  value = c(90, 10, 5)
)
allocate_grazing_to_products(
  grass_land, grazer_intake, livestock_production
)
#> # A tibble: 3 × 5
#>    year area_code item_cbs_code value method_allocation
#>   <int>     <int>         <int> <dbl> <chr>            
#> 1  2010         1          2848  67.5 all              
#> 2  2010         1          2731   7.5 all              
#> 3  2010         1          2732  25   all