Optical properties of gumus acids of chernozem podzolized after applying litter and compostes on its basis
Authors: Skrylnik Ie. V. , Tovstiy Iu. M. , Popirniy M. A. 
Published: February 2020

Investigation of electronic absorption spectra of humic acids (HA) is considered as one of their objective diagnostic features and indicators of transformation of HA components. Electron absorption spectra of the HA in the visible and ultraviolet range, in general, are gentle curves, which monotonically decrease with increasing wavelength. However, even such spectra reveal the difference in the spectral properties of the HA not only of different soils, but also of one type under excellent soil conditions, which allows the use of spectrophotometric analysis as a sensitive method for the study of humic acids. A thorough study of the properties and nature of humus substances using modern methods helps to understand the features the formation of humus substances in different natural conditions. The purpose of the study is to determine the change in the qualitative composition of humic acids extracted from chernozem podzoled after application of the litter and compost on its basis by spectrophotometry. To achieve this goal, the following methods were used: modeling, laboratory analysis, mathematical and statistical. Field studies have been carried out to determine the effect of litter and compost on its basis on the formation of the molecular structure of humic acids from chernozem podzoled. The studies carried out by us, the electronic absorption spectra of humic acids of chernozem podzoled correspond to the curves typical for a class of humus, the shape of the spectrum does not change, which indicates the similarity in the molecular structure of humic acids, but differ in the angle of incidence in the region of the ultraviolet range. The qualitative composition of structural elements of humic acids is determined on the basis of the analysis of electron absorption spectra of humic acids in the spectral range of 200–800 nm. The change of optical characteristics of humic acids extracted from chernozem of podzolized after introduction of the litter and compost on its basis was determined. The application of chicken litter and compost (scent + husk) contributes to enhancing the aroma of humic acids and increasing their resistance to mineralization. It has been established that composting has a longer-lasting effect on the formation of the structure of humic acids of black podzolized soils on the introduction of non-composting litter. In the UV range (200–400 nm), we note the characteristic intensive absorption of light for humic acids extracted from chernozem podzolized after the introduction of chicken litter and compost (scent + husk), due to the loss of weakly colored peripheral chains of molecules. The character of the inclination of the curves determined by the ratio D 465/665 allows us to conclude that the humic acids extracted from the chernozem podzolized after composting (laced + husk) have a more condensed nucleus than the introduction of chicken litter and compost (laced + husk). It is determined that the intensity of the influence on the mobility of the aromatic electronic system of humic acids depends on the period of composting of the source material and is manifested in absorption spectra in the ultraviolet light range.