Abstract Pot experiments with soils from three contaminated sites and an additional field experiment were conducted. The aim of the experiments was to test different organic and inorganic soil amendments to heavy metal uptake and to alleviate toxicity in different agricultural crops. Elements in the extracts were measured by plasma emission spectroscopy (ICP‐AES). Cadmium in the extracts was measured by atomic absorption spectroscopy (AAS), with a heated graphite‐tube system (HGA). The results of the experiment were statistically evaluated by the LSD test. Almost all treatments had positive effects on crop productivity or reduced heavy metal uptake. Organic manures especially reduced manganese (Mn), chromium (Cr), and nickel (Ni) uptake. Iron (Fe) oxides contained in red mud, a by-product of the aluminum industry, reduced soil to plant transfer of zinc (Zn), Ni, cadmium (Cd), and Cr. The results from these experiments show that it is necessary to select and combine amendments taking into account both site...