Simulate soil organic carbon with the AMG model.

Analytical AMG trajectory: an active decomposing pool and an inert stable pool. The humification coefficient is selected from the carbon input type via whep::amg_h_by_input_type (default 0.15). The active pool relaxes to its steady state h * input / k; the stable pool is constant.

Usage

calculate_soc_amg(
  initial_soc_mgc_ha,
  c_input_mgc_ha_yr,
  years,
  clay_pct = NA,
  climate_modifier = 1,
  c_input_type = NA,
  init_mode = c("fixed_iom", "steady_state")
)

Source

Saffih-Hdadi, K. & Mary, B. (2008). doi:10.1016/j.soilbio.2007.08.022 .

Arguments

initial_soc_mgc_ha: Initial soil organic carbon stock (Mg C per ha).
c_input_mgc_ha_yr: Annual carbon input (Mg C per ha per year).
years: Number of years to simulate.
clay_pct: Soil clay content (percent); unused, kept for contract.
climate_modifier: Annual climate rate modifier (dimensionless), scaling the active-pool decomposition rate.
c_input_type: Carbon input type label used to look up the humification coefficient.
init_mode: Initial pool split. "fixed_iom" splits the supplied initial stock by the published stable fraction. "steady_state" ignores the supplied stock and starts from the analytical equilibrium ca_ss / (1 - f_iom) (active pool at its steady state ca_ss = h * input / k, stable pool the matching inert share).

Value

A tibble with one row per year: year, ca, cs and soc_total.

Examples

calculate_soc_amg(
  initial_soc_mgc_ha = 50,
  c_input_mgc_ha_yr = 2,
  years = 5
)
#> # A tibble: 6 × 4
#>    year    ca    cs soc_total
#>   <int> <dbl> <dbl>     <dbl>
#> 1     0 17.5   32.5      50  
#> 2     1 15.1   32.5      47.6
#> 3     2 13.1   32.5      45.6
#> 4     3 11.4   32.5      43.9
#> 5     4  9.92  32.5      42.4
#> 6     5  8.69  32.5      41.2