HUMIC SUBSTANCES AND VISCOSITY OF SOIL PASTES

Abstract

In the work, the influence of water content in soil pastes on their viscosity was studied by the method of vibrational viscometry and changes in viscosity were explained from the standpoint of the structural organization of humic substances (HS) of soils. It was found that the viscosity of pastes prepared from sod-podzolic soil, with a decrease in their water content below 36%, increases to values of 4000–4200 MPa sec, and then practically does not change. This contradicted the existing ideas about the viscosity of suspensions, which should continuously increase with a decrease in the water content in them. This phenomenon was explained from the standpoint of the presence in the soil paste another component in addition to water and soil particles (aggregates and microaggregates) – supramolecular formations (SF) from soil HS, which can separate from soil gels and pass into a dispersion medium. According to the literature data, SF of HS exist in soils in the form of fractal clusters (F-clusters) consisting of particles-molecules. Due to the high stability of F-clusters, it is possible to assume that soil particles sliding along F-clusters in pastes, and a change in the thickness of the F-cluster layer through which sliding occurs may not significantly influence the viscosity of soil pastes. The data obtained during the study of the viscosity of soil pastes confirm the importance of F-clusters in the occurrence of soil properties.