Mineral Materials as a Neutralizing Agent Used on Soil Contaminated with Copper

The aim of the investigation was to evaluate the response of plants, using black mustard (Brassica nigra L. Koch) as a model plant, to soil contamination with copper (0, 200, 400, 600 mg Cu kg−1 of soil), and to determine the effectiveness of the Cu immobilization with mineral neutralizing materials, such as lime, clay and zeolite. The plant yield depended on soil contamination and mineral amendments. In the series without neutralizing materials, the level of 600 mg Cu kg−1 reduced the yield and increased leaf greenness. Lime alleviated the toxicity of Cu in objects with 200 mg Cu kg−1. Zeolite slightly mitigated the harmful effects of Cu at the level of 400 and 600 mg kg−1. Zeolite lowered the SPAD index. In the chemical composition of plants, the content of Cu, K, Mg, Na and Ca in plants increased to 400 mg Cu kg−1, while the content of P decreased to 600 mg Cu kg−1. Among the materials, lime reduced the Cu accumulation in plants the most, followed by clay. Cu narrowed the majority of ratios and widened the Ca:P and K:Ca ratios in plants. The applied mineral materials, except lime, did not significantly affect the formation of these indicators.