Aridity and geochemical drivers of soil micronutrient and contaminant availability in European drylands

Dryland soils provide many societal and environmental services, such as food supply and biodiversity support. In Europe, most of dryland areas are devoted to agriculture. In the next decades, both European and worldwide drylands are expected to suffer with intensity the foreseen climate change-derived rise in aridity. Many studies have focussed on aridity-induced changes in major nutrients in drylands, but little is known on the impact of environmental and biogeochemical factors on micronutrients with critical role in life and inorganic contaminants with ecotoxicological implications. We analysed and explored drivers of total and available concentrations of micronutrients (Co, Cu, Fe, Mo, Mn, Ni and Zn) and contaminants (As, Cd and Pb) in 148 soil samples collected from European drylands covering a wide range of aridity and of other geochemical parameters. The availability of micronutrients increased with their total content, decreased with pH and was enhanced by organic C content. Aridity decreased the availability of Fe, a key element in human diet. Concerningly, our findings also highlight the scarcity of this micronutrient in European drylands, as well as of some other important micronutrients like Zn and Mo in agricultural soils. Total content was the main driver of the availability of Cd and Pb, and organic matter exerted synergistic effects on contaminant release. Our data show the need for precise management practices to be incentivised by agricultural and environmental policies in order to ensure micronutrient supply and avoid contamination, thus maintaining proper level of agricultural productivity and simultaneously preserving dryland ecosystems.

JRC.D.3 - Land Resources