Abstract <p>At present, there are few data on changes in the elemental composition of components of agrocenoses under the influence of chemicalization agents during the growing season. The aim of the work was to assess changes in the elemental composition of the soil-plant system in different periods of plant growth under the conditions of mineral fertilizers application on soddy-podzolic sandy loamy soil (Stagnic Podzols (Abruptic, Pantoarenic, Bathyloamic, Aric)). Concentrations of mobile forms of Fe, Mn, Ni, Cu, Co and Zn have been determined in soil samples of the field experiment in the Tver oblast, taken at different stages of growth of winter rye plants during one season—in October (sprouting), April (tillering), June (earing), and August (full ripeness). Concentrations of elements in conjugated samples of rye plants have been estimated. It was shown that the period of sampling can have a significant influence on the results of assessing the contents of mobile species of elements. An increase in the content of Mn and Zn in the aboveground organs of rye plants with an increase in the rate of mineral fertilizers was found for samples taken at the stage of sprouting. It was shown that the content of mobile forms of elements in the soils of the field experiment weakly correlate with the concentrations of elements in the aboveground organs of plants.</p>