| Main authors: | Luuk Fleskens, Coen Ritsema, Zhanguo Bai, Violette Geissen, Jorge Mendes de Jesus, Vera da Silva, Aleid Teeuwen, Xiaomei Yang |
| iSQAPERiS editor: | Jane Brandt |
| Source document: | Fleskens, L et al. (2020) Tested and validated final version of SQAPP. iSQAPER Project Deliverable 4.2, 143 pp |
The indicators are assessed by
- calculating an overall potential for soil property improvement;
- calculating an overall soil threat level; and iii) listing the top-3 soil properties and soil threats needing attention (Figure 21).
Figure 21
The potential for soil improvement is expressed as a percentage. For any given land use, the average soil would score 50%. Scores of less than 50% mean the soil is better than average; scores greater than 50% indicate that the soil is poorer than average. Extreme values (close to 0 or 100%) are rare due to the skewed distributions and not all soil quality indicators scoring good or bad across the board.
The soil parameters needing attention are those with a potential for improvement score of higher than 67% (i.e. at least a third of soils in the same pedo-climatic zone and under the same land use score better for these parameters).
For any given land use, only soil parameters that can be improved by management are taken into account. The actual values of each these parameters is assessed by comparing the location-specific value with the optimum value found in all locations with similar climate and soil type for a certain land use (arable or grassland). The optimal value is either the minimum or maximum value depending on the soil parameter, or an optimum value in the case of pH. The percentile rank of the location assessed within the range of values determines the improvement score, which can theoretically range between 0 and 100%. The average of the improvement scores for individual soil parameters is calculated for the overall potential for soil improvement score.
The overall threat level is the arithmetic mean of individual soil threat scores for which data is available (low=1, medium=2, high=3). For “soil nutrient depletion” and “contamination by heavy metals” only the worst individual score of nutrients or metals is taken into account.
Soil threats needing attention are all those individual threats with a high score.
Note: For full references to papers quoted in this article see