Fertilizer pollution measures the application rates of agricultural fertilizers — Nitrogen (N), Phosphorus (P) and Potassium (K) — and estimates the fraction that escapes the agricultural system and becomes environmental pollution. The indicator provides quantitative information on the impact of intensive agriculture on three interconnected phenomena: eutrophication of surface water bodies, groundwater contamination from nitrate leaching, and greenhouse gas emissions (N₂O) from denitrification and nitrogen volatilisation.
Nitrogen has the most severe environmental consequences: up to 50% of applied nitrogen can disperse into the environment through leaching, volatilisation as ammonia (NH₃), and denitrification into nitrous oxide (N₂O), a greenhouse gas with 265 times the warming potential of CO₂ (Galloway et al., 2008). Phosphorus, while less mobile, is the primary driver of eutrophication in lakes and slow-moving water bodies. Potassium excess contributes to soil salinisation and structural degradation.
The KPI uses the NPKGRIDS dataset (Global Fertilizer Application Rates) from the University of Minnesota / Global Landscapes Initiative (Ludemann et al., 2022), at 10 km resolution. The dataset provides separate application rates for:
Estimates cover 175 crop classes aggregated globally for the reference year 2020 (WRD_NPKGR_20).
Loss fractions applied:
| Nutrient | Loss fraction | Main mechanisms |
|---|---|---|
| Nitrogen (N) | 50% | Nitrate leaching, NH₃ volatilisation, N₂O denitrification |
| Phosphorus (P) | 15% | Surface erosion, agricultural runoff |
| Potassium (K) | 30% | Leaching, deep percolation |
The calculation produces 3 separate layers: fertilizer_pollution_n, fertilizer_pollution_p, fertilizer_pollution_k. Each layer represents the estimated quantity of nutrient dispersed into the environment (in kg/ha/year) within and around the study polygon. Visualisation uses bilinear interpolation and a green→red colourmap with gamma correction γ=0.4 to emphasise high-pollution areas.
Technical note: a single request with map_layer_type="fertilizer_pollution" automatically generates all 3 layers (N, P, K).
| Code | Name | Provider | Resolution | Year |
|---|---|---|---|---|
WRD_NPKGR_20 | NPKGRIDS — Global Fertilizer Application Rates | University of Minnesota / Global Landscapes Initiative | 10 km | 2020 |
| Indicator | Unit | Range | Inverted |
|---|---|---|---|
fertilizer_pollution_n | kg/ha | [0, 100, 300, 700, 1500, 10000] | Yes |
fertilizer_pollution_p | kg/ha | [0, 20, 60, 150, 300, 1600] | Yes |
fertilizer_pollution_k | kg/ha | [0, 50, 150, 350, 700, 3300] | Yes |
Inverted = Yes: a lower value indicates less pollution and more favourable conditions for ecosystems.
Levels for fertilizer_pollution_n (Nitrogen dispersed, kg/ha):
| Level | Range (kg/ha) | Interpretation |
|---|---|---|
| E (Critical) | > 1,500 | Extreme nitrogen pollution; severe eutrophication and N₂O risk |
| D (Poor) | 700 – 1,500 | High nitrogen load; aquatic habitats severely at risk |
| C (Moderate) | 300 – 700 | Significant pressure; ecosystems under stress |
| B (Good) | 100 – 300 | Low-moderate impact; agriculture with room for improvement |
| A (Excellent) | 0 – 100 | Minimal impact; sustainable agricultural practices or natural areas |
map_layer_type="fertilizer_pollution" generates 3 separate layers (N, P, K)Responsible: Claudio Barbieri
fertilizer_pollution_n
(kg/ha)fertilizer_pollution_p
(kg/ha)fertilizer_pollution_k
(kg/ha)Uses the NPKGRIDS (Global Fertilizer Application Rates) dataset from the University of Minnesota / Global Landscapes Initiative at 10 km resolution, year 2020 (WRD_NPKGR_20). Provides application rates for 175 crop classes of: Nitrogen (N) in kg N/ha/year, Phosphorus (P) in kg P₂O₅/ha/year, Potassium (K) in kg K₂O/ha/year. Loss fractions applied: N 50% (leaching, volatilisation, denitrification), P 15% (erosion and runoff), K 30% (leaching). Generates 3 separate layers: fertilizer_pollution_n, _p, _k. Bilinear interpolation, green→red colourmap with gamma γ=0.4.