# Rapid Soil Tests for Assessing Soil Health
## 4 Discussion
### Towards a Uniform ABCDE Soil Health Scoring  
Internalizing the importance of'soil health' for human and environmental health requires the full involvement of the agrifood industry. In recent years, the global agrifood industry has promoted sustainable practices in food production, with emphasis on monitoring and verifying environmentally friendly and socially responsible practices, e.g., [23; 24; 25; 129]. Depending on world regions, [PERSON] and [PERSON] [130] listed the following approximate order in the focus of the agrifood industry: animal welfare > soil health > water footprint > deforestation > biodiversity > waste management > GHG emissions and climate change > food waste > plastic use. Despite the strong focus on soil health (second after animal welfare), the authors found that soil health assessments were qualitative, relying on self-reporting and limited data collection efforts [130]. Objective and quantifiable measures and targets for improved soil health were absent. We argue that soil health claims should be supported by solid soil health tests and monitoring, for the benefit of farmers,society, and the environment. A single soil test reflects a missed opportunity because the two broad-spectrum soil tests discussed here allow for the assessment of a broad range of agronomically, environmentally, and economically useful indicators  
The thresholds for EC, SOC:clay ratio, and Olsen P--for the ABCDE score (Table 4) have been proposed by the European Commission [51], but no clear thresholds have been proposed yet for the other indicators. For heavy metals, we have selected 0.01 M CaCl\({}_{2}\)-extractable cadmium (Cd), and for biodiversity the results of the PLGA method for inclusion in the ABCDE score. Thresholds for biodiversity are based on the methodology outlined in 'Four approaches to setting soil health targets and thresholds in agricultural soils' by [PERSON] et al. (2024) [131], using the so-called 'distribution' approach, combined with literature references. For Cd, we used a combination of a 'fixed' threshold, based on literature data, and a 'distribution' approach using five pro mille for the E-score, but corrected for the pH value (Figure 4). We have not included total nitrogen (N-total) as a descriptor for excess nutrients in soil (as proposed in the EU Soil Law, Part C), because most of the total nitrogen is part of soil organic matter ([PERSON] et al., 2017) [132]. The accumulation of organic matter is encouraged by various initiatives, including the 4/1000 Paris Agreement [133], and a high organic matter content in soil is seen as beneficial for SDG13 and soil health in general. Target soil pH values were included in the ABCDE score (Table 4; Figure 5), with a broad range (pH-CaCl\({}_{2}\) 5.5-6.5). A minimum target pH greater than 5.5 would enhance effective cation exchange capacity (CEC) [134], whilst a pH value > 6.5 will decrease the plant-available cadmium and some micronutrients (Figures 4 and 5). However, the optimum or target pH is a compromise, balancing the bioavailability of elements such as copper (Cu) and manganese (Mn), which are more bioavailable at low pH, and molybdenum (Mo), which becomes less available at low pH. New scientific insights regarding thresholds will require adjustments to the calculation method and ultimately to the ABCDE score. For instance, target SOC:clay ratios are currently under debate, and it is conceivable that factors such as iron (Fe) and aluminum (Al) (hydr)oxides--key drivers of the soil's capacity to sequester carbon and phosphorus--could be integrated into the system, linking actual SOC to achievable or potential SOC levels (e.g., Van Doorn) [135]. Further, the base saturation: aluminum ratio could serve as an additional indicator of soil acidification.