Speciation and bioavailability of soil nutrients: effect on crop production and environment

The agricultural production, determining the quality of the foodstuffs, depends on the biological characteristics of the crops and on the environmental properties, where soil environment plays a central role. Crops absorb water and nutritive elements from soil, but they can intake toxic elements as well. The potential benefits, or dangers, due to the presence of a certain element in soil, depend on its chemical speciation regulating its bioavailability, toxicity, environmental mobility, and biogeochemistry. Elements may exist in soil in different redox species and organic or inorganic forms. They may thus undergo different chemical processes occurring in solution, in the solid phase, or at the solid-water interface. The chemical speciation and bioavailability of the elements are affected by soil and environmental properties, which may undergo natural or anthropogenic modifications. As an example, we reported here some aspects linked to the chemical speciation, bioavailability and environmental fate of two chemically similar elements. The former, phosphorus, is a macronutrient element, essential for plant growth, while the latter, arsenic, is strongly toxic for most living organisms.