ABSTRACT
As shown in the rst edition of Handbook of Plant Nutrition, vanadium at low concentrations appears to stimulate the growth of plants, whereas at higher concentrations it is toxic (Pilbeam and Drihem, 2007). Although some vanadium comes from rocks, particularly igneous rocks (Cappuyns and Slabbinck, 2012), its origin in the soil is largely from anthropogenic activity. This includes as a pollutant from the use of vanadium as a catalyst in various industries, from the smelting of iron and other metals, from the addition of ash after burning of coal, and also from deposition from the atmosphere where it arises from the burning of oil (Pilbeam and Drihem, 2007; Cappuyns and Slabbinck, 2012). Another source of the element is fertilizers. Rock phosphate contains variable amounts of vanadium, depending on its place of origin, with a sample of South African rock phosphate being shown to contain 19 mg V kg−1, rock phosphate from Morocco 91 mg V kg−1, and a Jordanian sample as much as 123 mg V kg−1 (Vachirapatama et al., 2002). Some vanadium is present in commercial fertilizers, with a sample of NPK fertilizer from Thailand being shown to contain 181 mg V kg−1. A sample from Norway had 37 mg V kg−1, whereas an Australian sample was much purer and contained only 7.5 mg V kg−1 (Vachirapatama et al., 2002). The concentration of vanadium in the environment has been increasing since the Industrial Revolution, including in plant material.
