Weed BNF is calculated as: $$WeedsBNF = Weeds\_NPP\_MgN \times Ndfa_{weeds} \times Leg\_share_{weighted}$$
Where the weighted legume share accounts for both spontaneous leguminous weeds and deliberately seeded legume cover crops: $$Leg\_share = Leg\_spont \times (1 - CC\_share) + Leg\_seeded \times CC\_share$$
Environmental adjustments (N inhibition, temperature, water) are applied to the weed Ndfa when the corresponding columns are present (same mechanism as crop BNF).
Arguments
- x
Data frame with weed NPP data. Required columns:
- Weeds_NPP_MgN
Weed NPP in Mg N.
- LandUse
Land use type (Cropland, Grassland, etc.).
- Legs_Seeded
Legume fraction in seeded cover crops (0-1).
- Seeded_CC_share
Share of area with seeded cover crops (0-1).
Optional environmental columns: see
calc_crop_bnf.- k_n_synth
Numeric. Rate constant for N inhibition by synthetic N (default 0.0035).
- k_n_org
Numeric. Rate constant for N inhibition by organic N (default 0.0018).
- t_opt
Numeric. Optimal temperature (default 25).
- t_sigma
Numeric. Temperature Gaussian width (default 8).
Value
Data frame with added columns:
- Weeds_Ndfa_ref
Reference Ndfa for weeds.
- Weeds_Ndfa
Adjusted Ndfa for weeds.
- Weeds_leg_share
Weighted legume fraction.
- f_env_weed
Environmental adjustment factor.
- WeedsBNF
Weed BNF in Mg N.
Details
Estimates symbiotic BNF from leguminous weeds and seeded cover crops. The legume fraction in field vegetation is a weighted average of spontaneous weeds and seeded cover crops, based on management data.
Requires BNF object from `load_general_data()` (reads "Weeds" row for reference Ndfa and spontaneous legume share). Cover crop seeded share is only applied on cropland.
Examples
if (FALSE) { # \dontrun{
load_general_data()
weed_data |> calc_weed_bnf()
} # }