EFFECTS OF CHROMIUM(III AND VI) ON SPRING BARLEY AND MAIZE BIOMASS YIELD AND CONTENT OF NITROGENOUS COMPOUNDS

The aim of this study was to (1) determine the effects of trivalent Cr(III) or hexavalent chromium Cr(VI) soil contamination on biomass yield and nitrogenous compound content of spring barley (Hordeum vulgare L.) as the main crop and subsequently maize (Zea mays L.) grown successively, and (2) examine whether the neutralizing additives applied (compost, zeolite, and calcium oxide) may be effective in reducing adverse impact of chromium (Cr) on crops. Spring barley yield was markedly decreased by Cr compounds, particularly Cr(VI). In contrast, maize yield was significantly increased by Cr(VI). Hexavalent Cr exerted a greater effect than the Cr(III) form on nitrogen levels in spring barley. Chromium significantly increased ammonia nitrogen content in maize. The accumulation of NO3--N in plants treated with Cr(VI) was lower than in controls. The application of compost, zeolite, and calcium oxide onto the soil increased yield of maize only in pots containing Cr(III). Neutralizing additives exerted a positive, increased effect on the N-total content of maize but not spring barley, which was apparent with calcium oxide. Accumulation of NH4+-N in maize in pots with Cr(VI) was increased by all additives applied. The content of nitrate nitrogen in spring barley was predominantly affected by addition of compost and calcium oxide into the soil, producing a significant rise in NO3--N content. Chromium, especially Cr(VI), used at doses of 100 and 150 mg/kg soil exerted adverse effects in treated plants, particularly spring barley.