Estimate Nitrogen Rate using Holland & Schepers Method — estimate_N_rate_from_holland

This function estimates nitrogen (N) application rates based on NDVI values using the Holland & Schepers (H&S) algorithm. It calculates a sufficiency index (SI) for each pixel in the NDVI raster, then adjusts a base N rate to determine the recommended N dose.

Usage

estimate_N_rate_from_holland_schepers(
  ndvi_raster,
  base_N_rate = 50,
  plot = TRUE
)

Arguments

ndvi_raster: A raster::RasterLayer with NDVI (0–1), or a RasterBrick / RasterStack (layer named NDVI if present, else first layer).
base_N_rate: The base N rate (kg/ha) to be adjusted (default = 50).
plot: Logical indicating whether to create diagnostic plots (default = TRUE).

Value

A list containing:

dose_raster: RasterLayer with estimated N rates (kg/ha)
sufficiency_index_raster: RasterLayer with calculated sufficiency indices

Examples

if (FALSE) { # \dontrun{
library(raster)
# Load NDVI raster (replace with your data)
ndvi_raster <- raster(system.file("extdata/sample_ndvi.tif", package = "yourpackage"))

# Calculate N rates with plotting
result <- estimate_N_rate_from_holland_schepers(ndvi_raster, base_N_rate = 60)

# Visualize results
plot(result$dose_raster, main = "Recommended N Rates")
plot(result$sufficiency_index_raster, main = "Sufficiency Index")
} # }