Bioproductivity and Trace Element Composition of Cereal–Legume Mixtures in Technozem when Applying Mineral Fertilizers

Abstract

The influence of sowing cereal-legume mixtures and application of mineral fertilizers on technozem created after the liquidation of the tailing dump of the Dzhida Tungsten-Molybdenum Works (Republic of Buryatia) on the change of trace element concentrations in plants and formation of sod limiting the spread of pollutants and reducing environmental risks was assessed. The content of total and mobile forms of some trace elements in the upper loamy sand layer of technozem was higher than in the background soil, exceeded the median background for the soils of Transbaikalia and in some cases the maximum permissible concentrations, and was characterized as moderately hazardous by the coefficient of total contamination (Zc = 18.8); the lower loamy layer was nonhazardous (Zc = 4). It was revealed that the application of fertilizers reduced the concentration of trace elements and their accumulation coefficients in plants. According to the intensity of biological uptake, most of the elements in the aboveground phytomass belonged to the group of medium capture; in the underground phytomass, to the group of medium and intense uptake, which indicates its phytostabilization role. Bioproductivity of cereal–legume mixtures in the control was low. Fertilizer application increased the bioproductivity of the mixtures year to the moderate level on the second year and to the high level on the third year; the dense sod layer fixing the surface and contributing to the increase in the soil organic matter content in comparison with its initial amount was formed on the fourth year. The results of this study can be applied in remediation works on overburden dumps with the creation of technozems for phytostabilization and initiation of organic matter accumulation in these soils by sowing high-yielding perennial herbs and applying mineral fertilizers.