Stikstofgebruiksnorm 2025
This document provides a detailed explanation of the Dutch legal usage norm (gebruiksnorm) for nitrogen in 2025. It covers how the norm is calculated, the rules for catch crops and winter crops, and how the applied nitrogen counts towards this norm (opvulling).
Calculating the Gebruiksnorm (Usage Norm)
How the Norm Works
The nitrogen usage norm sets the maximum total effective nitrogen (in kg N/ha) that can be applied to a field. The calculation follows a step-by-step process to find the most precise norm based on various factors.
Calculation Steps
- Identify Main Crop: The main crop for 2025 is determined from your cultivation plan.
- Determine Geographical Context: The field's location is used to check:
- If it is in a Nutrient-Polluted Area (
NV-gebied), which results in a stricter (lower) norm. - The dominant soil region (
zand_nwc,zand_zuid,klei,veen, orloess).
- If it is in a Nutrient-Polluted Area (
- Find the Standard Norm: The main crop is looked up in the official RVO Table 2 (or Tabel 2g for NV-gebieden).
- Apply Specific Rules: The standard norm is refined with additional rules for certain crops:
- Temporary Grassland (
Tijdelijk grasland): The norm is adjusted based on the cultivation end date. - Potatoes (
Aardappelen): The norm is adjusted based on the potato variety. See RVO Tabel 2c. - Maize (
Maïs): The norm depends on the farm's derogation status. - Outdoor Flowers (
Buitenbloemen): A higher norm is applied for specific varieties.
- Temporary Grassland (
- Select the Final Norm: The final value is selected based on the field's soil region and
NV-gebiedstatus. - Apply Nitrogen Usage Norm Reduction (
Korting Stikstofgebruiksnorm): The norm can be reduced (korting) if catch crop (vanggewas) or winter crop (winterteelt) requirements were not met in the previous year on sand and loess soils.
How the FDM Calculator Determines the Norm
The fdm-calculator uses the calculateNitrogenUsageNorm function in fdm-calculator/src/norms/nl/2025/value/stikstofgebruiksnorm.ts, which relies on:
stikstofgebruiksnorm-data.ts: Contains the data from RVO Tabel 2 and Tabel 2g.input.ts: Defines the required inputs, such as derogation status, location, and crop data.
Vanggewassen en Winterteelten (Catch Crops and Winter Crops)
How the Rules Work
On sand and loess soils, the land must be covered during the winter to prevent nitrogen leaching. This can be achieved with a catch crop or a designated winter crop. Failure to comply results in a reduction of the nitrogen usage norm for the following year.
1. Winter Crop Exception
No reduction is applied if the main crop of the current year is a designated winter crop (winterteelt). These crops provide sufficient ground cover and nitrogen uptake.
Official Source: RVO Tabel 2F Vanggewassen en winterteelten
2. Catch Crop Rules
If there is no winter crop, a catch crop (vanggewas) must be sown. The sowing date determines the reduction:
- No Reduction: Sown by October 1st.
- 5 kg N/ha Reduction: Sown between October 2nd and October 14th.
- 10 kg N/ha Reduction: Sown between October 15th and October 31st.
- 20 kg N/ha Reduction: No valid catch crop, sown on or after November 1st, or destroyed before February 1st.
How the FDM Calculator Implements These Rules
This logic is part of the calculateNitrogenUsageNorm function:
- Check for Winter Crop: The calculator checks if the current year's main crop is a winter crop.
- Check for Catch Crop: If not, it checks the previous year's cultivation data for a catch crop.
- Apply Reduction: The sowing date determines the reduction, which is applied to the current year's norm.
Calculating the Opvulling (Filling)
How the Filling Works
The filling is based on the effective nitrogen (werkzame stikstof) applied, which is calculated using an efficiency coefficient (werkingscoëfficiënt).
Official Source: RVO Tabel 9 Werkzame stikstof landbouwgrond 2025
Calculation Formula
Effective Nitrogen (kg N) = Applied Amount (kg or ton) × Total Nitrogen Content (%) × Efficiency Coefficient (%)
Efficiency Coefficients (Werkingscoëfficiënten)
| Mestsoort (Manure Type) & Herkomst (Origin) | Toepassing (Application) | Werkingscoëfficiënt (%) |
|---|---|---|
| Drijfmest en dunne fractie | ||
| Drijfmest van graasdieren (eigen bedrijf) | Met beweiding | 45 |
| Zonder beweiding | 60 | |
| Drijfmest van graasdieren (aangevoerd) | 60 | |
| Drijfmest van varkens | Klei en veen | 60 |
| Zand en löss | 80 | |
| Overige drijfmest en dunne fractie | 80 | |
| Vaste mest | ||
| Vaste mest van graasdieren (eigen bedrijf) | Bouwland (sep-jan) | 30 |
| Overig met beweiding | 45 | |
| Overig zonder beweiding | 60 | |
| Vaste mest van graasdieren (aangevoerd) | Bouwland (sep-jan) | 30 |
| Overige | 40 | |
| Vaste mest van varkens, pluimvee, nertsen | 55 | |
| Overig | ||
| Compost / Champost | 10 / 25 | |
| Kunstmest (Mineral fertilizer) | 100 |
How the FDM Calculator Determines the Filling
The calculateNitrogenFilling function in fdm-calculator/src/norms/nl/2025/filling/stikstofgebruiksnorm.ts uses the fertilizer type, application method, and the coefficients from table-9.ts to calculate the effective nitrogen.