Attribute reported fallow land to crops.

Distribute each country's FAOSTAT-reported fallow area among its crops using a precomputed allocation weight, adding the result to each crop's cropped physical area. The weight is typically gridded_fallow_weights(), which puts fallow on rainfed dryland cereals and rainfed monsoon rice and keeps it off irrigated/continuous systems.

The fallow magnitude comes from fallow_total (FAOSTAT "Land with temporary fallow", item 6640) — reported separately from temporary meadows/pastures, so it isolates real fallow from fodder.

Usage

attribute_fallow_to_crops(cropgrids, fallow_total, alloc_weight)

Arguments

cropgrids

Tibble of national crop areas with columns area_code, item_cbs_code, physical_ha (cropped physical area), harvested_ha.

fallow_total

Tibble of reported fallow area with columns area_code and fallow_ha.

alloc_weight

Tibble of area_code, item_cbs_code, weight giving the within-country allocation weight, e.g. from gridded_fallow_weights().

Value

A tibble with area_code, item_cbs_code, physical_ha (cropped physical area plus attributed fallow), and harvested_ha.

Examples

cropgrids <- tibble::tribble(
  ~area_code, ~item_cbs_code, ~physical_ha, ~harvested_ha,
  1L, 2511L, 500, 500,
  1L, 2807L, 400, 400
)
fallow_total <- tibble::tribble(~area_code, ~fallow_ha, 1L, 200)
# all weight on wheat -> the 200 ha reported fallow goes to wheat
alloc_weight <- tibble::tribble(
  ~area_code, ~item_cbs_code, ~weight,
  1L, 2511L, 1,
  1L, 2807L, 0
)
attribute_fallow_to_crops(cropgrids, fallow_total, alloc_weight)
#> # A tibble: 2 × 4
#>   area_code item_cbs_code physical_ha harvested_ha
#>       <int>         <int>       <dbl>        <dbl>
#> 1         1          2511         700          500
#> 2         1          2807         400          400