The indicator shows the nutrient status of the topsoil with the two main plant nutrients: phosphorus (expressed as P₂O₅) and potassium (expressed as K₂O) for the following land-use categories: arable land, permanent grassland, and permanent crops.
The measurements of plant-available phosphorus and potassium were evaluated according to the Guidelines for Scientifically Based Fertilization (Mihelič et al., 2010). For the purpose of developing this indicator, the original five fertility classes were merged into three interpretative categories:

The values are shown as frequencies (in %) of soil fertility levels.

Soil phosphorus (P₂O₅) status shows large differences among land uses. On arable land, the situation is relatively balanced: 39% of soils are phosphorus-deficient, 34% reach optimal values, and 27% are excessively supplied. This indicates that arable soils face both risks of deficiency, which can reduce yields, and risks of surplus, which increase the potential for runoff and water pollution. In permanent crops (orchards, vineyards), the picture is split into thirds – deficient, optimal, and excessive – reflecting the diversity of management practices. The most pronounced deficiency is observed in grasslands, where as much as 78% of soils are insufficiently supplied with phosphorus, 14% are optimal, and only 8% excessive. The phosphorus impoverishment of grasslands is linked to fertilization practices: mineral fertilizers are rarely applied, livestock manures contain relatively low levels of phosphorus, and continuous removal of biomass through mowing and grazing further depletes P. This can lead to reduced growth and lower forage quality. The results highlight the need for balanced, targeted fertilization adapted to land use.

Soil potassium (K₂O) status also shows clear differences between land uses. Almost half of arable soils (46%) are potassium-deficient, 32% are optimal, and 22% are excessive. This indicates a considerable risk of deficiency, especially in crops with high potassium requirements. In permanent crops, the situation is more favorable – more than half of soils (52%) are optimally supplied, pointing to relatively balanced fertilization, although about a quarter are deficient and another quarter excessive. The largest deficiency occurs in grasslands, where 60% of soils are potassium-deficient, only 21% are optimal, and 19% excessive. These results are somewhat unexpected, since grasslands are often fertilized with livestock manures, which are rich in potassium. However, it is well known that potassium binds less strongly to soil (especially in light soils) and is therefore more mobile and prone to leaching. The findings emphasize the need for systematic potassium supplementation on grasslands and arable land, while avoiding surpluses in permanent crops.

Combined phosphorus (P₂O₅) and potassium (K₂O) status reveals very distinct patterns among land uses. On arable land, 18% of soils are simultaneously deficient in both P and K, 11% are optimal, and 12% excessive. This shows that the share of soils with balanced nutrient supply is relatively low, while deficiency or surplus predominates. In permanent crops, the situation is somewhat better: 19% of soils are optimal in both nutrients, while 13% are deficient and 15% excessive, again reflecting heterogeneous fertilization practices. The most critical situation is in grasslands, where as much as 50% of soils show simultaneous deficiency of both P and K, only 2% are optimal, and 6% excessive. This demonstrates that grasslands suffer from a double nutrient deficit, which can directly reduce productivity and forage quality. The results underline the need for more balanced fertilization, particularly in grasslands, where nutrient removal is intense and replacement insufficient.