Estimate crop below-ground (root) biomass.

Estimates root dry matter from above-ground biomass using an ensemble of an IPCC root:shoot ratio and a reference below-ground biomass per hectare. The nitrogen-input and irrigation adjustments activate only when their driver columns are present in x.

Usage

calculate_crop_roots(
  x,
  method = c("ensemble", "root_shoot", "reference"),
  weights = list(w_ref = 0.5),
  irrigation = c("except_paddy", "all_crops", "none")
)

Arguments

x

A tibble with item_prod_code, product_dm_t, residue_dm_t and area_ha. Optional n_input_kg_ha enables the nitrogen adjustment; optional water_regime enables the irrigation adjustment.

method

Root method: "ensemble" (default, weighted root:shoot + reference), "root_shoot" (root:shoot ratio only) or "reference" (reference below-ground biomass only).

weights

Named list; w_ref is the reference weight in the ensemble (0-1, default 0.5), used only when method = "ensemble".

irrigation

Which irrigated crops take the root:shoot factor of irrigation_adj (0.85 irrigated), used only when x has water_regime: "except_paddy" (default) applies it to every crop but paddy rice, which is flooded whether irrigated or not; "all_crops" applies it to every crop, as afsetools does; "none" applies no irrigation factor. Water stress raises root:shoot across crops (Eziz et al. 2017, doi:10.1002/ece3.3630; Kou et al. 2022, doi:10.3389/fpls.2022.1085409; Seidel et al. 2024, doi:10.1016/j.scitotenv.2024.176738), implying an irrigated factor of about 0.70 to 0.88 (whep#1536).

Value

The input tibble with root_dm_t and method_root, plus method_root_irrigation when x has water_regime.

Examples

calculate_crop_roots(
  tibble::tibble(
    item_prod_code = "15",
    product_dm_t = 87.9,
    residue_dm_t = 135.75,
    area_ha = 40
  )
)
#> # A tibble: 1 × 6
#>   item_prod_code product_dm_t residue_dm_t area_ha root_dm_t method_root
#>   <chr>                 <dbl>        <dbl>   <dbl>     <dbl> <chr>      
#> 1 15                     87.9         136.      40      67.4 ensemble