Chapter 13 The relationship between silicon and soil physical and chemical properties

Abstract

Soil minerals and organic matter control physical and chemical soil properties. Silicon (Si) is a basic mineral formatting element. The aim of our investigation was to obtain information about the effect of Si fertilization on physical and chemical soil properties. Silicon fertilization has been reported to result in increased soil exchange capacity, improved water and air regimes, transformation of P-containing minerals and formation of alumosilicates and heavy metal silicates. All these effects are caused by the change in soil mineral composition that results from silicate addition (Si fertilizers) and/or formation of new clay minerals, which are characterized by high biogeochemical activity. They have large surface area and are able to adsorb water, phosphates, potassium (K), nitrogen (N), aluminum (Al), and heavy metals. Adsorption may occur as chemosorptions or physical sorption. Cations (Al, heavy metals) usually are chemosorbed on Si-rich surface and lose their mobility. Phosphates and N are weakly adsorbed and remain in plant-available form. Amorphous silica, montmorillonite, and vermiculite represent the newly-formed minerals. These minerals affect the soil composition, and physical and chemical properties. The amounts of amorphous silica, monosilicic acids, and polysilicic acids in the soil are closely related to each other. Monosilicic acids regulate chemical properties of the soil solution. Polysilicic acids have an effect on soil physical properties.