The features of selenium content in the soil - plant system (review)

The research objective was to generalize the data on the content of selenium in the system the soil - the plant. Selenium is present in amino acids containing selenium, proteins and oxidation-reduction enzymes. It participates in various biological processes, in the oxidation of sulfur and lipids, methylation, destruction of hydrogen and radicals. The soil is the main source of the supply of plants with selenium. The content of selenium in agrocenosis is influenced by humus content and soils acidity, the properties and chemical composition of soil-forming rocks, climate, vegetation and geochemical characteristic of the landscapes of the region. Selenic pool of the soil consists of inorganic and organic compounds. The average content of selenium in the soils changes from 10 to 1000 mg/kg and more at the background value of 400 mg/kg. The average content of selenium in the soils of Russia is equal to 300 mg/kg. In regional conditions the content of selenium in the soils is influenced by the orientation of the soil-forming process, the level of their fertility and chemicalixation of agriculture. The greatest number of trace elements is noted in the soils with high content of humus, clay and oxides of iron. Selenium is one of biogenous elements influencing the growth processes, photosynthetic activity, winter hardiness, drought resistance and the efficiency of crops. The content of selenium in plants depends on the security of soils with a mobile form of the element, their agrochemical properties, weather conditions, the phase of development, specific and biological features of the cultures. The amount of selenium in the plants fluctuates from 10 to 1000 mg/kg of dry weight at aver- age values from 0.1 to 1.0 mg/kg. In the majority of regions of Russia on the soils with low supply of selenium its deficiency in the yield of crops was noted. The optimization of plants nutrition on the soils with the lack of trace elements requires introduction of selenic fertilizers. Under the influence of these fertilizers the efficiency of grain, forage and vegetable crops increases, which is necessary to consider when planning the system of fertilizer in the agrocenosis.