Use of soil sequential analysis for the study of hazard elements contamination in buckwheat and millet

The aim of this experiment was confirm use of sequential analysis of soil for study of arsen, cadmium and mercury contamination of buckwheat and milet, determine influence of nitrogen fertilization on accumulation of these elements in plant parts and compare differences among varieties of these crops. In year 1999, small-plot trials with seven varieties of buckwheat and eight varieties of common millet were established on sites in Ceske Budejovice, Humpolec and Cerveny Dvur (380, 525 and 420 m above sea level, moderate warm climatic region). The plots were sown in rows 12.5 cm wide, density of growth 200 (buckwheat) and 350 (millet) seeds per square meter. Area of a particular plot was 10 square m, and each variant had four replicates. Nitrogen fertilization (50 kg nitrogen per hectar) was applied befor sowing in the form of LAV (ammonium nitrate with limestone). No mechanical or chemical treatment was applied during the vegetation period. The hazard elements content (Cd, As, Hg) was analysed in all part of plants and in soil. Cadmium, arsenic and mercury were chosen for representation of elements in both ion forms and for healthy and nutrition importance using buckwheat and millet in a rational diet. Sequential analysis of soil was on water-soluble, exchange, bond with R2O3, organically fixed and residual fraction, performed by method EUR 14763 EN. Total content of observed elements in roots, leaves and stems and seeds was determined by UKZUZ Brno methodology. Statistical analyses were processed by software Statistica, version 5 (StatSoft, Inc., 2001). Sequential analysis gives more exact data than total content analysis. The mobile fractions-level of contamination relationship was exact only for roots of buckwheat and millet. Nitrogen fertilization applied on the beginning of vegetation decreased arsenic content and increased cadmium content in plants. Mercury content in plants was not significantly influenced by nitrogen fertilization. Varieties of buckwheat and millet have imponderable influence on accumulation of these elements in the plant in comparison with conditions of cadmium, arsenic and mercury mobility in soil. The content of cadmium, arsenic and mercury in roots of buckwheat and millet was more significantly influenced by mobility of these elements.