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Build the crop/soil N2O extension.

Source: R/crop_soil_n2o_extension.R
build_crop_soil_n2o_extension.Rd

Estimate IPCC 2019 Tier 1 nitrous-oxide emissions from nitrogen applied to managed soils, as a footprint extension keyed by (year, area_code, item_cbs_code) in kilograms of carbon-dioxide equivalent (CO2e). This is the soil-N2O analogue of build_livestock_ghg_extension() and feeds build_footprint() / compute_footprint() the same way.

Three nitrogen inputs to soil are included:

  • Synthetic fertiliser (F_SN): FAOSTAT reports it only as a country total (tonnes N per area_code per year), so it is allocated to crops in proportion to each crop's harvested area within the country-year (from get_primary_production()).

  • Applied manure (F_ON): FAOSTAT "Manure applied to soils (N content)" country total, allocated to crops by harvested area as for F_SN.

  • Crop residues (F_CR): the dry matter of above-ground residues returned to soil (from get_primary_residues(), net of the removed fraction) times the crop's residue nitrogen content (IPCC 2019 Table 11.1a).

N2O is then estimated with IPCC 2019 Refinement (Vol 4, Ch 11) Tier 1 factors (climate-aggregated): direct EF1 = 0.010; indirect via volatilisation EF4 = 0.010 applied to the volatilised fraction (FracGASF = 0.11 for synthetic, FracGASM = 0.21 for manure; crop residues do not volatilise, Eq 11.9); indirect via leaching FracLEACH = 0.24 times EF5 = 0.011. N2O-N is converted to N2O by 44/28 and to CO2e with the chosen GWP100.

Manure deposited by grazing animals (F_PRP, which uses the grazing EF3 on pasture) and below-ground residue N are further Tier 1 inputs not yet included.

Usage

build_crop_soil_n2o_extension(
  gwp = c("ar6", "ar5", "ar4"),
  residue_removed_frac = 0.45,
  data = list(),
  example = FALSE
)

Arguments

gwp

100-year global warming potential standard for N2O, "ar6" (default, 273), "ar5" (265) or "ar4" (298).

residue_removed_frac

Fraction of above-ground crop residue removed from the field (for feed, fuel or construction) and therefore not returned to soil. Defaults to 0.45, a global mid-range value; country-specific removal (gleam_fracremove) is a future refinement.

data

Optional named list of pre-loaded inputs to avoid remote reads: primary_prod (get_primary_production(), for harvested area), fertilizer (the faostat-fertilizer-nutrients pin), manure (the faostat-emissions-livestock pin) and primary_residues (get_primary_residues()). Each falls back to its reader when absent.

example

If TRUE, return a small fixture instead of reading remote data. Defaults to FALSE.

Value

A tibble with columns year, area_code, item_cbs_code, impact_u (soil N2O in kilograms CO2e) and method_soil_n2o.

Examples

build_crop_soil_n2o_extension(example = TRUE)
#> # A tibble: 2 × 5
#>    year area_code item_cbs_code  impact_u method_soil_n2o    
#>   <int>     <int>         <int>     <dbl> <chr>              
#> 1  2010        10          2511 412612200 IPCC_2019_Tier1_AR6
#> 2  2010        10          2513 176833800 IPCC_2019_Tier1_AR6