Estimate ammonia-N volatilisation from applied nitrogen.

Three independent methods for the fraction of applied nitrogen volatilised as ammonia. "ipcc" (IPCC 2019 Tier 1, n_fun.r:914-930) needs only fert_type and applies a single global fraction. "manner" (the default) dispatches each row through the process-based calculate_manner_nh3() MANNER model (Task C4), which requires far more driver detail (see Details); this asymmetry in input requirements is intentional, not an oversight. "manner_default" dispatches each row through calculate_manner_nh3_default() instead, the same process-based organic-manure model but with technique/incorporation_delay_h filled in from a documented gross-assumption blend rather than required as driver columns.

Usage

calculate_nh3(x, method = "manner", example = FALSE)

Arguments

x

A tibble with n_input_t (numeric, tonnes N) and fert_type. method = "manner" additionally requires manner_fertiliser and the driver columns listed in Details. method = "manner_default" additionally requires manner_fertiliser and the driver columns listed in Details, but NOT technique/incorporation_delay_h.

method

"manner" (default, process-based, per-row), "ipcc" (Tier 1, global fraction) or "manner_default" (process-based organic path with a gross-assumption technique/incorporation-delay blend, no technique/incorporation_delay_h columns required).

example

If TRUE, return a small fixture instead of computing from x. Defaults to FALSE.

Value

x with nh3_n_t and method_nh3 appended.

Details

method = "manner" requires x to already carry a manner_fertiliser column holding the exact calculate_manner_nh3() fertiliser key ("Urea", "AN", "CAN", "AS", "cattle_slurry", "pig_slurry", "FYM", "poultry_manure" or "urban") plus every driver column that key's path needs: soil_ph, rate_kg_ha, rainfall_mm, irrigated, temp_c, temp_c_annual_mean for the synthetic path; rainfall_mm, irrigated, windspeed_ms, technique, system, temp_c, incorporation_delay_h, species (unless manner_fertiliser == "urban") for the organic path. This function does not infer manner_fertiliser from fert_type (e.g. which synthetic sub-type "Synthetic" maps to is not determined by fert_type alone) and does not silently fall back to "ipcc" or invent driver values: a missing required column aborts naming exactly which column is absent. Each row is dispatched to calculate_manner_nh3() individually (MANNER's dispatch is inherently per-row categorical, not vectorizable across the coefficient joins); this row-iteration is isolated to a small private helper.

method = "manner_default" requires the same manner_fertiliser column (restricted to the organic-manure keys, since the gross default only covers that path) plus rainfall_mm, irrigated, windspeed_ms, system, temp_c and species (unless manner_fertiliser == "urban"). It does NOT require technique or incorporation_delay_h: those are filled in from manner_default_technique_mix (see calculate_manner_nh3_default()'s Details for the gross-assumption reasoning), never invented per-row.

Examples

calculate_nh3(example = TRUE)
#> # A tibble: 1 × 4
#>   n_input_t fert_type nh3_n_t method_nh3
#>       <dbl> <chr>       <dbl> <chr>     
#> 1        10 Synthetic     1.1 ipcc