Növénytermelés / Volume 62 / Issue 2 (June 2013) / pp. 51-66
The impact of microelement load on maize (Zea mays L.) on calcareous sandy soil
We examined the impact of 0, 30, 90, 270 kg ha-1 microelement load on maize on calcareous sandy soil in the Danube-Tisza mid-region. The microelement salts were applied on one occasion when the experiment was launched in the spring of 1995 in the forms of Cr2(SO4)3, K2Cr2O7, CuSO4, Pb(NO3)2, Na2SeO3 and ZnSO4. The 6 elements×4 loads represented 24 treatments×3 replications=72 plots with 7×5=35 m2 plot size. In accordance with the usual characteristics of sandy soils, the production site had bad water management and it was sensitive to drought and weakly supplied with NPK. The ploughed layer contained 0.7-1.0% humus and 2-3% CaCO3 and the groundwater level is 5-10 m. Each year, we applied basic fertilisation of 100 kg ha-1 N, 100 kg ha-1 P2O5 and 100 kg ha-1 K2O in the whole experiment. Main results:
4. During the 6-month-long growing season of maize, the total amount of precipitation was 326 mm in a relatively favourable distribution; therefore, 4.4 t ha-1 grain yield and 6.5 t ha-1 stem yield were obtained in 2002. As a result of the higher load of 270 kg ha-1 Se and Zn in the 7th year, the grain yield decreased to less than its quarter. Toxicity was mostly observed in the generative phase. No other elements had depressive effect.
5. The concentration of Cr, Pb and Cu moderately increased in the stem yield at the time of harvesting, while there was no increase in the grain. The Zn content increased 4 times in the stem and also increased by 20% in the grain in comparison with the control. Se showed hyperaccumulation, as its content increased more than 100 times its previous value both in the stem and the grain. Both the grain and stem yield of maize became useless for foraging purposes due to the extreme Se accumulation. 25 g Cr, 27 g Pb, 153 g Cu, 643 g Zn and 1093 g Se were incorporated into the 11 t ha-1 above-ground biomass at the time of harvesting. Considering similar experimental conditions, phytoremediation would need 10 800 Cr years, 10 600 Pb years, 1765 Cu years, 420 Zn years and 245 Se years in the case of 270 kg ha-1 element uptake.
6. On uncontaminated soil, the specific element content, i.e., the average element content of 1 t grain + its secondary yield was 33-16-17-25-12 =N-P2O5-K2O-CaO-MgO kg t-1. The production site is calcareous sandy soil and it is rich in Ca and Mg, as well as P as a result of the 100 kg ha-1 year-1 P2O5 fertilisation, but it is weaky supplied with K. All these observations are shown by the high specific Ca, Mg, P and the relatively lower K parameters.
Keywords: maize, microelement load, toxicity, field experiment, sandy soil