Convert fractional NDTI drop to SIPNET tillage effectiveness — ndti_to_sipnet

Maps the fractional NDTI drop produced by the CCMMF NDTI pipeline to tillage_eff_0to1 for use in the PEcAn events JSON schema and written to SIPNET events.in by write.events.SIPNET.

Usage

ndti_to_sipnet_tillage(delta_ndti, no_till_threshold = 0.3, slope = 2.5)

Arguments

delta_ndti: numeric vector. Fractional NDTI drop in \[0, 1\], computed as (max_before_min - min_val) / max_before_min from a smoothed NDTI time series over the fallow season.
no_till_threshold: numeric scalar. delta_ndti values at or below this threshold are mapped to zero effectiveness (no-till). Default 0.30, based on Dietze & Kanee (pers. comm.).
slope: numeric scalar. Slope of the linear response above no_till_threshold. Default 2.5, which produces a ramp from 0 at delta_ndti = 0.30 to 1 at delta_ndti = 0.70 (i.e. 1 / (0.70 - 0.30)). Output is clamped to \[0, 1\].

Value

numeric vector of tillage_eff_0to1 values, same length as delta_ndti, clamped to \[0, 1\]. NA inputs propagate to NA outputs.

Details

NDTI drops after tillage as residue is incorporated into soil. The fractional drop over the fallow season is a proxy for tillage intensity. Default thresholds are from Dietze & Kanee (pers. comm.). The slope parameter can be calibrated once field data (SOC or soil respiration) are available.

References

Daughtry, C.S.T., Hunt, E.R., Doraiswamy, P.C., McMurtrey, J.E. (2005). Remote sensing the spatial distribution of crop residues. Agronomy Journal, 97(3), 864–871. doi:10.2134/agronj2004.0291

Examples

ndti_to_sipnet_tillage(c(0.25, 0.50, 0.80))
#> [1] 0.0 0.5 1.0

# Custom slope for sensitivity analysis
ndti_to_sipnet_tillage(c(0.25, 0.50, 0.80), slope = 2.0)
#> [1] 0.0 0.4 1.0