Compute the RothC and HSOC annual climate rate modifier.

Annual abc rate-modifying factor of the RothC / HSOC soil-carbon model: the temperature factor a, the topsoil-moisture-deficit factor b, and the plant-cover factor c, averaged over the supplied monthly series. The same function modifies HSOC decomposition.

Usage

soc_rate_modifier_rothc(
  temp_c,
  water_minus_pet_mm,
  clay_pct,
  soil_cover,
  soil_depth_m = .soc_topsoil_depth_m()
)

Source

Coleman, K. & Jenkinson, D. S. (1996). RothC-26.3: a model for the turnover of carbon in soil. doi:10.1007/978-3-642-61094-3_17 . Moisture deficit and cover terms as implemented in an earlier regional historical SOC reconstruction.

Arguments

temp_c

Numeric monthly air temperature series (degrees Celsius).

water_minus_pet_mm

Numeric monthly water surplus series (precipitation minus potential evapotranspiration, mm), used to accumulate the topsoil moisture deficit.

clay_pct

Soil clay content (percent).

soil_cover

Vegetated soil-cover fraction (0 bare, 1 fully covered); a scalar or monthly series.

soil_depth_m

Topsoil depth over which the moisture deficit is accumulated (metres). Defaults to 0.3, the layer every soil-carbon stock in this package is defined over; RothC's published expression is calibrated on its own 0-23 cm layer and is rescaled to this depth.

Value

The annual mean of the monthly abc product (a single numeric).

Examples

soc_rate_modifier_rothc(
  temp_c = c(1.2, 7.8, 15.0),
  water_minus_pet_mm = c(-10, 5, 20),
  clay_pct = 20,
  soil_cover = 0
)
#> [1] 0.969915