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Calculate Nitrogen Fertilization Requirement

Source: R/calculate_N_fertilization.R
calculate_N_fertilization.Rd

Calculates the final nitrogen fertilization requirement (N_fert) from a nitrogen balance result.

Usage

calculate_N_fertilization(n_balance, method = "standard")

Arguments

n_balance

A data frame returned by N_balance() containing nitrogen balance components.

method

The calculation method to use. Default is "standard" which uses the DPI formula: N_fert = A - B + C1 + C2 + D - E - F - Forg - G

Value

A numeric value representing the nitrogen fertilization requirement in kg/ha.

Details

This function calculates the final nitrogen fertilization requirement based on the nitrogen balance components. If the result is negative, it returns 0 (no fertilization needed).

The standard (DPI) formula is:

N_fert = A - B + C1 + C2 + D - E - F - Forg - G

Where:

  • A: Crop nitrogen demand

  • B: Soil nitrogen supply

  • C1, C2: Leaching losses

  • D: Immobilization losses

  • E: Nitrogen from previous crop residues

  • F: Nitrogen from previous years' organic fertilization (0 if not in balance)

  • Forg: Nitrogen from organic fertilizer (current year)

  • G: Natural nitrogen contribution

Examples

# Calculate nitrogen balance
balance <- N_balance(
  expected_yield_tons_ha = 15,
  crop = "Mais trinciato (classe 700)",
  ccp = "Spring-summer crop 100-130 days",
  sand = 50, clay = 35,
  Ntot = 1.2, SOM = 1.2, CN = 9.5,
  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
)

# Calculate required nitrogen fertilization
n_fert <- calculate_N_fertilization(balance)
print(paste("Required N fertilization:", round(n_fert, 2), "kg/ha"))
#> [1] "Required N fertilization: 50.55 kg/ha"