Nitrogen Rate Estimation from NDVI using Calibration — estimate_N_rate_from_calibration

This function estimates nitrogen (N) application rates based on NDVI values using either a two-point or three-point calibration method.

Usage

estimate_N_rate_from_calibration_curve(
  raster,
  minN,
  maxN,
  meanN = NULL,
  calibration_type = "two-point",
  plot = FALSE
)

Arguments

raster: A raster::RasterLayer with NDVI values, or a RasterBrick / RasterStack (the layer named NDVI is used if present, otherwise the first layer).
minN: The minimum N rate (kg/ha) corresponding to the minimum NDVI.
maxN: The maximum N rate (kg/ha) corresponding to the maximum NDVI.
meanN: The mean N rate (kg/ha) corresponding to the mean NDVI (only used for three-point calibration).
calibration_type: The type of calibration to perform: "two-point" or "three-point". Default is "two-point".
plot: A logical value indicating whether to create plots (default is FALSE).

Value

A RasterLayer object with the estimated N rates based on the chosen calibration method.

Examples

# Load example NDVI raster (replace with your own)
# ndvi_raster <- raster::raster(system.file("extdata/s2.tif", package = "NFert"))

# Two-point calibration
# n_rate_raster_2pt <- estimate_N_rate_from_calibration_curve(ndvi_raster, minN = 40, maxN = 60)

# Three-point calibration
# n_rate_raster_3pt <- estimate_N_rate_from_calibration_curve(ndvi_raster, minN = 40, meanN = 50,
# maxN = 60, calibration_type = "three-point")