Effect of organic fertilizers and siderates on colloidal chemical characteristics of labile fractions of humic acids of the sod-podzolic soil

Abstract

Goal. To study the effect of organic fertilizers and siderates on the colloidal chemical characteristics (size of colloidal particles) of the labile fraction of humic acids of the sod-podzolic soil. Methods. Field (sampling of soil samples), laboratory (analysis of soil samples by methods of dynamic light scattering and spectroscopy), mathematical and statistical (processing of experimental data). Results. Soil samples were taken on the territory of the Volyn State Agricultural Experimental Station in the Volyn oblast in the zone of Polissia. It was found that the introduction of organic fertilizers and siderates into the soil contributed to an increase in the content of humic acids of the labile fraction of organic matter of the sod-podzolic soil, and an increase in the polydispersity of the solution of the labile fraction of humic acids of the sod-podzolic soil, which was due to the appearance of a fine population of nano-particles up to 100 nm in size. By adding manure, the content of aromatic condensed structures and polydispersity of the humic acid fraction significantly increased, which was associated with the formation of a clear and stable bimodal distribution of colloidal particles with a high content of populations of nano-particles and submicrofractions with a size of 150–250 nm. The use of siderates caused the population of nano-particles to fluctuate, which reduced the polydispersity of the labile fractions of humic acids and slowed the formation of an unstable bimodal distribution. Conclusions. With the use of an organic fertilizer system, the content of hydrophobic aromatic non-polar structures increased, which led to an active neoplasm of humus substances and an increase in polydispersity due to the accumulation of stable populations of nano-particles that increased the size of humic aggregates and contributed to the stability of fractions of labile humic acids.