Potassium fertilizer pollution quantifies the estimated environmental loss of potassium (as K₂O) from agricultural fertilizer applications across the landscape. While potassium is an essential macronutrient for plant growth, its excessive application leads to significant environmental consequences that are often underestimated compared to nitrogen and phosphorus pollution. Excess potassium in soils disrupts the cation balance (Ca²⁺/Mg²⁺/K⁺ ratios), leading to magnesium and calcium deficiency in plants and degradation of soil structure through dispersion of clay particles.
From a biodiversity perspective, potassium over-application has profound effects on soil microbiome composition and mycorrhizal fungal networks. Elevated potassium concentrations suppress the colonisation of arbuscular mycorrhizal fungi (AMF), which are critical for nutrient cycling, soil aggregation, and plant community diversity. High K⁺ availability reduces plant dependence on mycorrhizal symbiosis, weakening the underground fungal networks that connect plant communities and facilitate inter-species nutrient transfer. Furthermore, soil salinisation caused by potassium salts (KCl, K₂SO₄) increases osmotic stress on soil fauna — including earthworms, springtails, and mites — thereby reducing soil biodiversity and impairing decomposition processes essential for healthy terrestrial ecosystems.
The data are derived from the NPKGRIDS v1.08 dataset (Nature Scientific Data, 2024), produced by the University of Minnesota / Global Landscapes Initiative, at ~10 km resolution (5 arc-minutes) for the year 2020, disaggregated across 175 crop classes. A 30% pollution fraction is applied to estimate the potassium lost to the environment primarily through leaching into groundwater and soil solution.
K2Orate) is read from the NPKGRIDS NetCDF file stored on AWS S3gnuplot2 colormap with PowerNorm gamma = 0.4, range 0–3,266 kg K₂O/haUnit: kg K₂O/ha/year
| Code | Name | Provider | Resolution | Availability |
|---|---|---|---|---|
WRD_NPKGR_20 | NPKGRIDS v1.08 | Nature Scientific Data / University of Minnesota | ~10 km (5 arc-min) | 2020-01-01 — 2020-12-31 |
| Indicator | Unit | Range | Inverted |
|---|---|---|---|
fertilizer_pollution_k | kg K₂O/ha/yr | [0, 50, 150, 350, 700, 3300] | Yes |
Inverted = Yes: a lower value indicates less potassium pollution and conditions more favourable for soil biodiversity.
| Level | kg K₂O/ha/yr | Interpretation |
|---|---|---|
| A (Excellent) | 0 – 50 | Minimal potassium pollution — healthy cation balance, intact mycorrhizal networks |
| B (Good) | 50 – 150 | Low potassium pollution — limited impact on soil biota |
| C (Moderate) | 150 – 350 | Moderate potassium pollution — early signs of cation imbalance and reduced AMF colonisation |
| D (Poor) | 350 – 700 | High potassium pollution — significant soil salinisation risk |
| E (Critical) | > 700 | Very high potassium pollution — severe impacts on soil structure, microbiome, and biodiversity |
gnuplot2 colormap with PowerNorm gamma = 0.4 enhances visual contrast in the low-to-medium pollution rangeThe Fertilizer Pollution K map shows potassium (K2O) pollution using NPKGRIDS v1.08. K2O application rates are summed over 175 crop classes. A 30% loss fraction (leaching) is applied. Data is bilinearly interpolated from ~10 km to ~1.7 km and displayed with gnuplot2 colormap (PowerNorm gamma=0.4).