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Allocate field-available manure to cropland and grassland by crop.

Source: R/manure_allocation.R
allocate_manure_to_land.Rd

Distributes the manure nitrogen, carbon and volatile solids that survive management (the output of apply_management_losses()) across cropland crops and grassland, with a local agronomic cap and an explicit overflow path. The collected/housed manure fills cropland up to each crop's cap (weighted by West-2014 receptivity by default), the surplus spills onto grassland up to the grassland cap, and any residual beyond all reachable sinks follows the disposal_method. The in-situ grazing stream is deposited on grassland where it falls, uncapped. Carbon and volatile solids ride along with each stream at its post-storage bundle ratio, so mass is conserved by construction.

Usage

allocate_manure_to_land(applied, gridded = list(), options = list())

Arguments

applied

A tibble from apply_management_losses() with at least year, territory (a stringified area_code, see estimate_n_excretion()), sub_territory, stream, applied_n, applied_c and applied_vs.

gridded

A named list describing the land surface for each polity:

  • crops: a tibble keyed by year, territory, sub_territory, crop (a code, as.character(item_prod_code); this function treats it as an opaque label but the downstream nitrogen balance resolves it through items_prod_full, so a name is deprecated there) with the allocation weight (manure_n_receptivity for "area_x_receptivity", crop_n_demand for "crop_n_demand") and the cap basis (crop_n_cap, t N, for "potential_uptake"/"realised_removal"; crop_area_ha for "fixed_ceiling").

  • grass (optional): a tibble keyed by year, territory, sub_territory with grass_n_cap (t N) or grass_area_ha. The grassland cap is scaled by f_n_tolerance on the same footing as the uptake-based crop caps (not for "fixed_ceiling"). Absent grassland means no grassland sink (cap zero).

options

A named list of method options: method ("area_x_receptivity" default, or "crop_n_demand"), cap_method ("potential_uptake" default, "realised_removal", or "fixed_ceiling"), f_n_tolerance (default 1.2, applied to the uptake-based caps), fixed_ceiling_kg_ha (default 170, EU Nitrates) and disposal_method ("over_apply_local" default, "unmanaged_disposal", or "retain_unallocated").

Value

A tibble with one row per allocation target: year, territory, sub_territory, land_use ("Cropland"/"Grassland"/"Disposal"/ "Unallocated"), crop, source_stream ("collected"/"grazing"), manure_type ("Excreta"/"Solid"/"Liquid", carried from applied when present; each allocated row's N/C/VS is split across the manure_types in proportion to their share of the cell's collected N, so the capacity-filling math itself stays pooled), applied_n, applied_c, applied_vs, over_cap and the method_allocation, method_cap and disposal_method provenance columns. The N split by manure_type is exact (mass-conserving per type); applied_c and applied_vs are split by the SAME N-proportional share, not by each manure_type's own C:N/VS:N ratio, so a per-manure_type carbon or volatile-solids figure does not reflect that type's actual composition (e.g. solid vs. liquid manure have materially different C:N). Callers needing manure-type-specific carbon/VS (e.g. CH4 potential by system) should not rely on the manure_type-broken-out applied_c/ applied_vs columns without accounting for this.

Examples

applied <- tibble::tribble(
  ~year, ~territory, ~sub_territory, ~stream, ~manure_type,
  ~applied_n, ~applied_c, ~applied_vs,
  2020L, "203", NA, "collected", "Solid", 80, 800, 40,
  2020L, "203", NA, "grazing", "Excreta", 20, 380, 12
)
crops <- tibble::tribble(
  ~year, ~territory, ~sub_territory, ~crop, ~manure_n_receptivity, ~crop_n_cap,
  2020L, "203", NA, "44", 6, 50,
  2020L, "203", NA, "15", 4, 40
)
allocate_manure_to_land(applied, list(crops = crops))
#> # A tibble: 3 × 14
#>    year territory sub_territory land_use  crop  source_stream manure_type
#>   <int> <chr>     <lgl>         <chr>     <chr> <chr>         <chr>      
#> 1  2020 203       NA            Cropland  44    collected     Solid      
#> 2  2020 203       NA            Cropland  15    collected     Solid      
#> 3  2020 203       NA            Grassland NA    grazing       Excreta    
#> # ℹ 7 more variables: applied_n <dbl>, applied_c <dbl>, applied_vs <dbl>,
#> #   over_cap <lgl>, method_allocation <chr>, method_cap <chr>,
#> #   disposal_method <chr>