One of the most common elements in the earth's crust is silicon. In soils, its content varies widely. One hundred years ago, to the role of silicon in agriculture and human nutrition was not paid aƩention. But with the intensification of agricultural production in addition to the basic elements, nitrogen, phosphorus, potassium, the importance of which for crop yields is recognized, much aƩention was paid to secondary and trace elements, in particular, silicon. The aim of the research was to determine the content of soluble silicon compounds in the arable layer of chernozem-type soils depending on their particle size distribution. The research was conducted on arable lands of Novoushitsky district of Khmelnytsky region. In soil samples were determined: particle size distribution and content of fractions of different sizes according to SSTU 4730:2007; pH of salt extract according to SSTU ISO 10390:2001; humus content according to SSTU 4289:2004; the content of exchangeable compounds of calcium and magnesium by extraction with 1.0 M KCl solution. Silicon compounds in soils were determined by the method of Mullen and Riley with extraction of silicon by the method of V.V.Matichenkov. Studies that were conducted on agricultural soils of Khmelnytsky region have shown that the content of silicon compounds in soils is related to the particle size distribution of the soil, the values of exchangeable acidity, humus content, as well as the composition and content of exchangeable cations. The average values of readily-available silicon compounds in the studied soils of agricultural lands of Novoushitsky district of Khmelnytsky region range from 87 to 120 ppm SiO2, and hard-soluble - 520-854 ppm SiO2. To assess the content of silicon compounds in the soils of Ukraine and the need for the use of silicon fertilizers, we propose to use the ratio of the content of readily-available (active) and hard-soluble (potential) silicon. Optimal values should be 3-4 for the ratio of exchangeable calcium to fixed silicon, and 5-6 for the ratio of hard-soluble to readily-available silica. The studied soils of Novoushitsky district of Khmelnytsky region have low-deficient and non-deficient balance of silicon, both of readily-available and hard-soluble forms. Since the yield of winter wheat was closely related to the content of readily-available silicon compounds (r = 0.74 ± 0.09), it is important to continue research on the use of silicon fertilizers.
readily-available silica, hard-soluble silica compounds, reaction of soil medium, exchangeable cations, particle size distribution of soil.