THE EFFECTS OF ZINC FERTILIZATION ON CADMIUM CONCENTRATION IN WHEAT-GRAIN

Although the effect of Zn in soil on Cd uptake by plants has been stud ied extensively, there appears to be no consensus in the literature ab out the interactions. Furthermore, the majority of investigations have studied soils containing elevated concentrations of Cd or Zn as a res ult of pollution, e.g., the application of sewage sludge to the soil. The accumulation of Cd by wheat (Triticum aestivum L.) grain grown at nine sites across South Australia was investigated. Applications of lo w rates of Zn fertilizer (up to 5.0 kg Zn ha-1) were found to markedly decrease the Cd concentration in wheat grain grown in areas of margin al to severe Zn deficiency. No further significant decreases in Cd con centration in grain occurred at higher rates of applied Zn. Effectiven ess of applied Zn on grain Cd concentration decreased with time since application. Grain Cd concentrations decreased with fresh and residual applications of Zn fertilizer (up to 5.0 kg Zn ha-1). Soil tests may provide useful guides to situations where Cd concentrations in grain m ay be beneficially decreased by Zn applications.