The effect of 0, 30, 90, and 270 kg ha-1 microelement load on winter wheat was examined on calcareous sandy soil on the Danube-Tisza mid-region. The microelements were applied in the forms of Cr2(SO4)3, K2Cr2O7, CuSO4, Pb(NO3)2, Na2SeO3, ZnSO4 once in the spring of 1995, when the experiment was established. The number of plots was 72 (6 elements × 4 loads = 24 treatments × 3 replications) and the plot size was 7 × 5 = 35 m2. The production site had bad water management, it was drought sensitive and weakly supplied with NPK, as it is typical among sandy soils. The ploughed layer contains 0.7-1.0% humus and 2–3% CaCO3, the soil water level is 5-10 deep. 100 kg N ha-1, 100 kg P2O5 ha-1 and 100 kg K2O ha-1 active ingredients are applied as basic fertilisers every year in the whole experiment. Main results:

1. Due to the unfavourable rainfall conditions / weather, there was 3 t ha-1 grain yield + 3 t ha-1 secondary yield on the unpolluted control soil. In the 3rd year of the experiment, the highest 270 kg ha-1 Se and Zn treatment was shown to be toxic. As a result of the Zn load, the above-ground biomass at the time of yield decreased to its 60%, whereas the Se load caused the total destruction of wheat and the existing weed species.

2. On polluted soil during harvest, the Cu content of the secondary yield doubled, whereas the Zn tripled and the Pb quadrupled in content, the Cr content increased by a magnitude and the concentration of Se increased its content 2540-fold. The grain yield was shown to be genetically more protected. No change was shown in the Cr(III), Cr(VI), Pb and Cu element content in the grain. The Zn content increased by 80%, whereas Se increased its content 2640-fold in comparison with the control. The mobility of Se in the soil-crop system is not obstructed, even the mass flow transport within the crop is unobstructed. The wheat grain became unfit for human consumption on the soil strongly polluted with Se and Zn. The grain became inadequate for foraging purposes due to the Se pollution.

3. The maximum Se uptake was observed in the 90 kg ha-1 treatment and it accounted to 442 g ha-1. The highest Zn uptake was 193 g ha-1 in the 90 kg Zn ha-1 treatment. In the treatment that did not cause yield depression, the following highest amounts of elements were incorporated into the 6 t ha-1 biomass: 40 g Cu ha-1, 14 g Cr ha-1 and 3 g Pb ha-1 that could be measured during the highest, 270 kg ha-1 load. If unchanged conditions are assumed, the 90 kg ha-1 Se would need 204 years to be taken up, whereas it would take 466 years to take up Zn. Using a similar estimation, the amount of time necessary for the phytoremediation of the 270 kg ha-1 pollution is nearly 7 thousand Cu-years, 19 thousand Cr-years and 90 thousand Pb-years.

4. The so-called specific element content of the 1 t grain yield and its secondary yield was about 30 kg N, 7–8 kg (8–10 kg K2O), 4–5 kg P (9–11 kg P2O5) and around 3 kg Ca, Mg and S. Our data could serve as an guidance when giving technical advices in relation to the calculation of the element demand of wheat.

Keywords: winter wheat, microelement load, toxicity, element uptake, phytoremediation