Skip to main content

createFunctionsForNorms

@svenvw/fdm-source

@svenvw/fdm-source / fdm-calculator/src / createFunctionsForNorms

Function: createFunctionsForNorms()

createFunctionsForNorms(b_region, year): object

Defined in: fdm-calculator/src/norms/index.ts:7

Parameters​

b_region​

"NL"

year​

"2025"

Returns​

aggregateNormsToFarmLevel()​

aggregateNormsToFarmLevel: (input) => AggregatedNormsToFarmLevel

Aggregates the norm values from individual fields to the farm level. This function takes the output per field of the norm calculation, multiplies each norm by the field's area, and sums these values across all fields to provide total norms for the farm.

The result are three numbers (manure, nitrogen, phosphate) expressed as totals, not per hectare.

Parameters​

input​

InputAggregateNormsToFarmLevel

An array of field data, each containing field ID, area, and calculated norms.

Returns​

AggregatedNormsToFarmLevel

An object containing the total aggregated norms for manure, nitrogen, and phosphate for the farm.

Example​

const fieldData = [
  {
    b_id: "field1",
    b_area: 10, // hectares
    norms: {
      manure: { normValue: 100, normSource: "Source A" }, // kg N/ha
      nitrogen: { normValue: 150, normSource: "Source B" }, // kg N/ha
      phosphate: { normValue: 50, normSource: "Source C" }, // kg P2O5/ha
    },
  },
  {
    b_id: "field2",
    b_area: 5, // hectares
    norms: {
      manure: { normValue: 90, normSource: "Source A" }, // kg N/ha
      nitrogen: { normValue: 140, normSource: "Source B" }, // kg N/ha
      phosphate: { normValue: 45, normSource: "Source C" }, // kg P2O5/ha
    },
  },
];

const aggregatedNorms = aggregateNormsToFarmLevel(fieldData);
// aggregatedNorms will be:
// {
//   manure: (100 * 10) + (90 * 5) = 1000 + 450 = 1450,
//   nitrogen: (150 * 10) + (140 * 5) = 1500 + 700 = 2200,
//   phosphate: (50 * 10) + (45 * 5) = 500 + 225 = 725,
// }

calculateNormForManure()​

calculateNormForManure: (input) => Promise<DierlijkeMestGebruiksnormResult> = getNL2025DierlijkeMestGebruiksNorm

Determines the 'gebruiksnorm' (usage standard) for nitrogen from animal manure for a given farm and parcel in the Netherlands for the year 2025.

This function implements the rules and norms specified by the RVO for 2025, taking into account derogation status and location within NV-gebieden.

Parameters​

input​

NL2025NormsInput

An object containing all necessary parameters for the calculation. See DierlijkeMestGebruiksnormInput for details.

Returns​

Promise<DierlijkeMestGebruiksnormResult>

An object of type DierlijkeMestGebruiksnormResult containing the determined nitrogen usage standard (normValue) and a normSource string explaining the rule applied.

Remarks​

The rules for 2025 are as follows:

  • Standard Norm (No Derogation): If the farm does NOT have a derogation permit, the norm is 170 kg N/ha from animal manure.
  • Derogation Norm (With Derogation): If the farm HAS a derogation permit:
    • Inside Natura2000-Gebied: If the parcel is located in a Natura200-Gebied or within 100m of it, the norm is 170 kg N/ha from animal manure.
    • Inside GWBG-Gebied: If the parcel is located in a GWBG Gebied or within 100m of it, the norm is 170 kg N/ha from animal manure.
    • Inside NV-Gebied: If the parcel is located in a Nutriënt-Verontreinigd Gebied, the norm is 190 kg N/ha from animal manure.
    • Outside NV-Gebied: If the parcel is NOT located in a Nutriënt-Verontreinigd Gebied, the norm is 200 kg N/ha from animal manure.

See​

calculateNormForNitrogen()​

calculateNormForNitrogen: (input) => Promise<GebruiksnormResult> = getNL2025StikstofGebruiksNorm

Determines the 'gebruiksnorm' (usage standard) for nitrogen for a given cultivation based on its BRP code, geographical location, and other specific characteristics. This function is the primary entry point for calculating the nitrogen usage norm according to the Dutch RVO's "Tabel 2 Stikstof landbouwgrond 2025" and related annexes.

Parameters​

input​

NL2025NormsInput

An object of type NL2025NormsInput containing all necessary data:

  • farm.is_derogatie_bedrijf: A boolean indicating if the farm operates under derogation.
  • field.b_centroid: An object with the latitude and longitude of the field's centroid.
  • cultivations: An array of cultivation objects, from which the hoofdteelt (main crop) will be determined.

Returns​

Promise<GebruiksnormResult>

A promise that resolves to an object of type GebruiksnormResult containing:

  • normValue: The determined nitrogen usage standard in kilograms per hectare (kg/ha).
  • normSource: The descriptive name from RVO Table 2 used for the calculation.
  • kortingDescription: A description of any korting (reduction) applied to the norm. Returns null if no matching standard or applicable norm can be found for the given input.

Throws​

If the hoofdteelt cultivation cannot be found or if geographical data queries fail.

Remarks​

The function follows a comprehensive, multi-step process to accurately determine the correct nitrogen norm:

  1. Identify Main Crop (hoofdteelt): The determineNL2025Hoofdteelt function is called to identify the primary cultivation (b_lu_catalogue) for the field based on the provided cultivations array. This is the first step to narrow down the applicable nitrogen standards.

  2. Determine Geographical Context:

    • isFieldInNVGebied: This asynchronous helper function is called to check if the field's centroid falls within a Nitraatkwetsbaar Gebied (NV-gebied). Fields in NV-gebieds often have stricter (lower) nitrogen norms.
    • getRegion: This asynchronous helper function determines the specific soil region (e.g., "zand" for sandy soil, "klei" for clay soil) based on the field's coordinates. Nitrogen norms can vary significantly by soil type. Both functions use efficient spatial queries to retrieve this information.

  3. Match Nitrogen Standard Data: The nitrogenStandardsData (loaded from a JSON file) is filtered to find all entries (NitrogenStandard objects) whose b_lu_catalogue_match array includes the identified b_lu_catalogue of the hoofdteelt.

  4. Refine by Variety (for Potatoes): If the hoofdteelt has a specific b_lu_variety (e.g., for potatoes), the matching standards are further filtered. Potatoes can have "high" (varieties_hoge_norm) or "low" (varieties_lage_norm) nitrogen norms based on their variety. If a specific variety match is not found, it falls back to "overig" (other) potato norms if available.

  5. Select the Most Specific Standard: If multiple NitrogenStandard entries still match after initial filtering and variety-specific refinement, the function attempts to select the most specific one. This prioritization ensures that detailed rules (e.g., those without variety_type or sub_types if a direct match is found) are applied correctly.

  6. Retrieve Applicable Norms: The getNormsForCultivation helper function is called with the selectedStandard and other relevant parameters (variety, derogation status, cultivation end date). This function applies a hierarchy of rules (sub-type periods, variety-specific, derogation-specific) to return the precise NormsByRegion object for the cultivation.

  7. Calculate Final Norm Value: From the applicableNorms object, the function retrieves the specific norms for the determined region. The final normValue is then selected: if the field is in an is_nv_area, the nv_area norm is used; otherwise, the standard norm is applied.

  8. Apply "Korting" (Reduction): The calculateKorting function is called to determine if a reduction should be applied based on the previous year's cultivations and the field's region. The calculated kortingAmount is then subtracted from the normValue.

This detailed process ensures that the calculated nitrogen usage norm is accurate and compliant with RVO regulations, taking into account all relevant agricultural and geographical factors.

See​

calculateNormForPhosphate()​

calculateNormForPhosphate: (input) => Promise<FosfaatGebruiksnormResult> = getNL2025FosfaatGebruiksNorm

Determines the 'gebruiksnorm' (usage standard) for phosphate for a given field based on its land type (grasland/bouwland) and soil phosphate condition, derived from P-CaCl2 and P-Al soil analysis values.

This function implements the "Tabel Fosfaatgebruiksnormen 2025" and the "Differentiatie fosfaatgebruiksnorm 2025" rules from RVO.

Parameters​

input​

NL2025NormsInput

An object containing all necessary parameters for the calculation. See FosfaatGebruiksnormInput for details.

Returns​

Promise<FosfaatGebruiksnormResult>

An object of type FosfaatGebruiksnormResult containing the determined phosphate usage standard (normValue) and the fosfaatKlasse (the phosphate class determined from the soil analysis). Returns null if a norm cannot be determined.

Remarks​

The function operates as follows:

  1. Determine Phosphate Class: The getFosfaatKlasse helper function is used to classify the soil's phosphate condition ('Arm', 'Laag', 'Neutraal', 'Ruim', 'Hoog') based on the provided a_p_cc and a_p_al values and whether it's grassland or arable land. This classification directly uses the lookup tables provided by RVO for 2025.
  2. Retrieve Base Norm: The determined fosfaatKlasse is then used to look up the corresponding base phosphate norm from the fosfaatNormsData.json file.
  3. Apply Land Type: The specific norm for either grasland or bouwland is selected from the base norm based on the is_grasland input parameter.
  4. Return Result: The function returns the final normValue and the fosfaatKlasse.

See​

collectInputForNorms()​

collectInputForNorms: (fdm, principal_id, b_id) => Promise<NL2025NormsInput> = collectNL2025InputForNorms

Collects all necessary input data from the FDM to calculate the Dutch (NL) norms for the year 2025.

This function orchestrates fetching data for a given farm, its fields, cultivations, and soil analyses, and structures it into a format suitable for the various NL 2025 norm calculation functions.

Parameters​

fdm​

FdmType

An initialized FdmType instance for data access.

principal_id​

string

The ID of the principal initiating the data collection.

b_id​

string

The unique identifier of the field for which to collect data.

Returns​

Promise<NL2025NormsInput>

A promise that resolves to an NL2025NormsInput object, containing all the structured data required for the norm calculations.