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

Eduardo Moreno‐Jiménez,César Plaza,Sara Aceña‐Heras,Arwyn Jones,Alberto Orgiazzi,Hugo Saiz

doi:10.1111/ejss.13163

Abstract

AbstractDryland soils provide different societal and environmental services, such as food supply and biodiversity support. In Europe, most of the dryland areas are devoted to agriculture. In the next decades, both European and worldwide drylands are expected to suffer with increased intensity due to the expected climate change‐derived rise in aridity. Many studies have focussed on aridity‐induced changes in major nutrients in drylands, but little is known of the impact of environmental and biogeochemical factors on micronutrients with critical roles in life, and as 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. 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 adequate levels of agricultural productivity and simultaneously preserving dryland ecosystems.Highlights Drylands are important for food production in Europe and sensitive to climate change. The occurrence of metals in European Union dry soils and the drivers influencing them were studied. Some micronutrients (Fe, Mo and Zn) were scarce while contaminants were abundant. SOC, pH and clays were the main drivers of element availability; aridity reduced Fe. Agricultural practises are needed to ensure nutrient supply and prevent contamination.

Highlights

Soils are key to supporting healthy ecosystems and supply goods and services, and are pivotal for achieving the UN's Sustainable Development Goals (Keesstra et al, 2016; Lorenz et al, 2019)
Soils are vulnerable to human-induced effects such as climate change, contamination, erosion and land use (Jie et al, 2002; Lal, 2009)
Intensive exploitation has strongly affected the physico-chemical properties of soils in the European Union (EU) over the last decades (Okpara et al, 2020; Toth et al, 2008), decreasing soil quality

Summary

| INTRODUCTION

Soils are key to supporting healthy ecosystems and supply goods and services, and are pivotal for achieving the UN's Sustainable Development Goals (Keesstra et al, 2016; Lorenz et al, 2019). In a context of climate change models that forecastg an increase in aridity in dryland areas, such as those in Southern Europe (Pravalie et al, 2019), the consequences for soil metallic micronutrients and contaminants are highly uncertain. Reducing this uncertainty is critical for agricultural planning and environmental preservation. Despite focusing on the south of Europe, our results could be extended to a rising number of agricultural regions worldwide, not just in drylands, showing similar soil properties (pH neutral to basic and low organic C content) and affected by increased aridity

| MATERIALS AND METHODS

Findings

| RESULTS