Physicochemical properties of surface soils in European wheat fields under conventional and organic farming: Current status and climate change influence

Recognizing the critical role of healthy soils in global food security, this large-scale study evaluated the physicochemical properties of 188 wheat soils across nine European pedoclimatic zones and assessed the influence of climate and farming system. Soils exhibited substantial variability in bulk density (0.7–1.7 g/cm), pH-H2O
(5.0–9.1), effective cation exchange capacity (4.5–42.0 cmolc/kg), base saturation (14%-100%), organic matter (1.6%-19.1%), and total inorganic carbon (0.7–106.3 g/kg). Redundancy Analysis (RDA) showed that climatic and geographic factors were more strongly associated with soil properties than farming system, whose effects were significant but smaller and context-dependent. Mean annual temperature and precipitation were associated with soil pH, base saturation, organic matter, and inorganic carbon, and indirectly influenced bulk density and eCEC. Soil properties were primarily structured by climatic gradients, reinforcing climate as a dominant soilforming factor. Farming system effects were detectable but variable across pedoclimatic zones, indicating that management can locally modulate specific soil properties, although with lower explanatory power than climate. Based on these spatial associations and literature projections, warming trends may contribute to increased organic matter decomposition, higher bulk density, and reduced nutrient retention. Mediterranean regions appear particularly vulnerable due to declining precipitation, potentially linked to alkalinization and salinization. Although organic farming can locally enhance organic matter, reduce bulk density, and maintain inorganic carbon stocks, its effects are secondary to climate at the continental scale. These findings, based on spatial rather than temporal relationships, support region-specific soil management strategies integrating climate adaptation to sustain soil quality, productivity, and ecosystem services.