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Spatially-explicit Nitrogen Balance

Source: R/spatial_N_balance.R
spatial_N_balance.Rd

Applies N_balance() pixel-by-pixel to a set of soil-property rasters, returning one or more raster layers with the spatially-resolved balance terms.

Usage

spatial_N_balance(
  soil_stack,
  expected_yield_tons_ha,
  crop,
  ccp,
  oxygen_availability = "Normal",
  winter_rain,
  start_spring_rain,
  prev_crop,
  source = "Cattle slurry",
  fertorg_frequency = "every year",
  location = "Plain adjacent to urbanized areas",
  forg_quantity = 0,
  terms = c("A", "B", "C1", "C2", "D", "E", "F", "Forg", "G", "N_to_apply"),
  ...
)

Arguments

soil_stack

A RasterStack (or RasterBrick) whose layers encode the soil properties that vary in space. Required layers (matched by name, case-insensitive):

TN

Total soil nitrogen, pct

SOM

Soil organic matter, pct

Clay

Clay content, pct

Sand

Sand content, pct

CNratio

Carbon-to-nitrogen ratio (dimensionless)

expected_yield_tons_ha

Numeric scalar. Expected crop yield (t ha\(^{-1}\)).

crop

Character. Crop name (Italian or English, see resolve_crop()).

ccp

Character. Crop calendar period.

oxygen_availability

Character. Oxygen availability class (default "Normal").

winter_rain, start_spring_rain

Numeric scalars. Rainfall (mm).

prev_crop

Character. Previous crop.

source, fertorg_frequency, location, forg_quantity

Organic-fertilization parameters (see N_balance()).

terms

Character vector of balance terms to return as layers in the output RasterStack. Default c("A", "B", "C1", "C2", "D", "E", "F", "Forg", "G", "N_to_apply"). Use "all" to return every column of the N_balance() output.

...

Additional arguments passed to N_balance().

Value

A RasterStack with one layer per requested balance term, at the same resolution, extent and CRS as soil_stack.

Details

Agronomic and climatic parameters that do not depend on location within the field (yield target, crop, rainfall, previous crop, organic history) are treated as scalars: the spatial variability of the balance is driven exclusively by the soil-property rasters.

The function iterates over all non-NA cells. For a 96 \(\times\) 101 raster (~10 000 pixels) the computation takes approximately one second on a modern laptop.

See also

N_balance(), estimate_N_rate_from_holland_schepers()

Examples

if (FALSE) { # \dontrun{
library(raster)
ext <- system.file("extdata", package = "NFert")
soil <- raster::stack(
  file.path(ext, "Cremonesi_TN.tif"),
  file.path(ext, "Cremonesi_SOM.tif"),
  file.path(ext, "Cremonesi_Clay.tif"),
  file.path(ext, "Cremonesi_Sand.tif"),
  file.path(ext, "Cremonesi_CNratio.tif")
)
names(soil) <- c("TN", "SOM", "Clay", "Sand", "CNratio")

n_map <- spatial_N_balance(
  soil_stack = soil,
  expected_yield_tons_ha = 60,
  crop = "Mais trinciato (classe 700)",
  ccp  = "Spring-summer crop 100-130 days",
  oxygen_availability = "Normal",
  winter_rain = 160, start_spring_rain = 40,
  prev_crop = "Winter cereals straw removal",
  source = "Cattle slurry", fertorg_frequency = "every year",
  location = "Plain adjacent to urbanized areas",
  forg_quantity = 100
)
raster::plot(n_map[["N_to_apply"]])
} # }