A study conducted at the Free University of Berlin showed that the health of urban soils is being destroyed by the cumulative effects of several factors that may seem harmless individually.
Scientists modeled typical urban stressors: salt (from de-icing agents), microplastics (from tire wear), surfactants (detergents), drought, extreme heat, and soil compaction.
The key finding is that it is the combination, rather than any single factor, that leads to a critical deterioration of soil condition. For example, heat alone can accelerate microbial metabolism, but when combined with drought, it intensifies evaporation, concentrating pollutants and damaging soil aggregates. Similarly, microplastics alone did not cause significant harm, but in a "cocktail" with other stressors, they exacerbated negative effects.
Such synergistic effects weaken soil structure—it loses its ability to effectively absorb water, increasing the risk of flooding—and disrupt the functioning of microbial communities responsible for nutrient cycling.
The authors emphasize that traditional restoration approaches aimed at eliminating one obvious factor may be ineffective. To truly improve the health of urban soils, comprehensive measures are needed to reduce all types of stressors simultaneously.
