Nehézfém- és egyéb toxikus mikroelem-terhelés tartamhatása a főtermés mennyiségére szabadföldi kísérletben

The potentially harmful trace element load long-term field experiment was established in spring, 1991 on a calcareous chernozem soil, with 13 elements (Al, As, Ba, Cd, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sr, Zn), with 0-90-270-810 kg ha⁻¹ doses, by Prof. Dr. imre Kadar. As a first approach, the measure of yield losses, expressed in relative yields (O = 100%), were shown as an effect of the potentially harmful trace elements. In the averege of the 90-270-810 kg ha⁻¹ doses, the sequence of phytotoxic effect of the trace elements was as follows: Se > Cr > Cd > Al > Pb > As > Mo > Hg > Cu > Ni > Zn > Ba > Sr. Highest yield losses were caused by Se, Cr and Cd, while the smallest ones, by Ni, Zn, Ba and Sr. According to the number of phytotoxic years, element sequence was as follows: Se = As > Cr > Cd > Hg > Cu = Zn > Al = Mo > Ni = Pb > Ba = Sr. Of the 20 experimental years, most times Se, As, Cr and Cd elements, while, least times Ni, Pb, Ba and Sr elements proved to be phytotoxic. As an effect of the harmful element doses, Se, Cr and Cd elements were phytotoxic (showing more than 10% yield losses) from the 90 kg ha⁻¹ dose, Pb and Hg from the 270 kg ha⁻¹ dose, while, As and Mo, from the 810 kg ha⁻¹ dose, in the average of the phytotoxic years. From the point of view of both the measure of yield losses, and the number of phytotoxic years, the trace elements applied in anionic forms (and, among them, the non-essential ones) proved to be the most harmful. As a second approach, the measure of phytotoxicity was evaluated depending on crops, as well as on time elapsed since initial high dose trace element applications. Among the crops, highest phytotoxicities were shown by sunflower, spinach, and winter barley, while, smallest ones by three-, two- and one year old alfalfa. As the time elapsed, yield losses became lower and lower. From the 13ᵗʰ year of the trial, average yield losses sinked below 10%. Among the potentially toxic elements, cadmium must receive special attention, because a significant percentage of Cd has remained in easily soluble form in the plought layer, and, even after almost twenty years following application, this fraction has diminished only slightly on our calcareous chernozem soil.