A FIELD-STUDY ON THE INFLUENCE OF SOIL-PH ON TRACE-ELEMENT LEVELS IN SPRING WHEAT (TRITICUM AESTIVAM), POTATOES (SOLANUM-TUBEROSUM) AND CARROTS (DAUCUS-CAROTA)

Soil pH is one of the main factors influencing the solubility and avai lability of trace elements in arable soils. Thus pH can affect the tra ce element contents of agricultural crops and thereby indirectly influ ence human health. The aim of this study was to determine Cd, Ni, Zn, Cu, Mn, Cr, Al and Se contents in spring wheat, potatoes and carrots ( Cd, Ni and Zn) and estimate their correlations with certain soil facto rs (surface and subsurface soil pH and organic matter content) governi ng the plant availability of these elements. Commercial fields were sa mpled in Sweden in order to cover a wide range of soil types with resp ect to pH, soil texture and organic matter content. Concentrations of Zn, Mn, Ni (grain) and Cd (straw) in spring wheat (n=43); Cd, Ni, Zn,M n, Cu and Al in potatoes (n=69); and Cd, Ni and Zn in carrots (n=36) s howed significant negative correlations with surface soil pH (0-25 cm) . The Se content of potatoes and Cr content of spring wheat straw were positively correlated with soil pH. Stepwise multiple regressions inc luding a combination of soil pHs (0-25 and 25-50 cm) and organic matte r contents (0-25 cm) showed that the organic matter content as well as the surface and subsurface soil pH significantly influenced concentra tions of several trace elements in one or more of the studied crops. I t was concluded that, if acid deposition together with other acidifyin g processes (fertilisation, harvest of biomass, etc.) are not balanced by a sufficient amount of liming there might be a decrease in the pH of arable soils, which, in turn will lead to decreased levels of Se in edible crops but an overall increase concentrations of other trace el ements.