The results of a vegetation experiment on the humus horizon of sod-podzolic sandy loam soil (Albic Retisol) are presented. Until 1990, sewage sludge was added to the soil, which resulted in the formation of complex polyelement pollution with HM, and even after 30 years, the soils remained contaminated. During this period, the phosphorus content decreased by 4 times, potassium by 1.5, and the organic carbon content by 1.6 times. The content of HM also decreased significantly compared to the initial level: Cd by 5 times, Zn and Cu by 1.5 times, Pb by 1.4 times. Vegetation experiments using zeolite clinoptilolite, zeolite ZION and the humic preparation “Vibrostand” showed the possibility of reducing the content of HM using ameliorants in Vicia sp. plants and, to a smaller extent, in Avena sp. A study of the effect of ameliorants on the content of HM in plants grown on soils fertilized with sewage sludge 30 years ago showed that their application changes the content of HM and their distribution within plant organs. Moreover, Vicia sp. plants accumulate significantly less HM than Avena sp., which can be used on soils taking into account their pollution levels. The ameliorants used in the experiments reduce the content of Cd, Zn, Cu and Ni in Vicia sp. plants by 40–60%, but the standard content of HM in plants could not be achieved with such a high level of soil pollution. For Avena sp. plants, the ameliorants were less effective.
Plekhanova et al. (Sun,) studied this question.