Comparative assessment of the use of humic substances derived from brown coals for technogenic landscapes reclamation

Abstract

The objective of the study. To identify the prospects for the use of humic preparations for the restoration of disturbed coal-mining areas, by assessing the relationship between their biological activity and the structural-group composition. Location and time of the study. The study was carried out in the Novokuznetsk district of the Kemerovo region (N 54.14o N and E 87.10o E) in 2020. Methodology. The study of the structure-group composition of humic preparations was carried out by the 13C NMR spectroscopy. Evaluation of the effect of humic preparations was performed in a series of plot experiments setup in the reclaimed and non-reclaimed areas of the coal mining spoils. The properties of the soils substrates of the technogenic landscapes were determined by traditional soil methods. The effect of the preparations was assessed by the dry phytomass production and pod yields of Vícia villósa vetch, as well as the phytomass production of the Avéna satíva + Vícia villósa mixture. Statistical analysis of the data was carried out by the principal components analysis. Main results: Comparison of humic preparations obtained from brown coals of the Tisulsky (Kansk-Achinsky basin) and Tyulgansky (South Ural basin) deposits showed that, in general, all preparations positively affected phytomass production and pod yeild. However, in different conditions of technogenic landscapes and in relation to different plant species, the effect could manifest itself in different directions. A stable positive effect from pre-sowing seed treatment was achieved only with substrates depleted in natural humic substances (humus and peat), and with optimal moisture. Under such conditions, the greatest influence was exerted by preparations obtained from brown coals of the Tisulsky deposit of the Kansk-Achinsky basin, and their naturally oxidized form, which are characterized by a high proportion of oxygen-containing aliphatic (CO-Alk-O), as well as aromatic (СAr) groups. At the same time, under moisture deficit, the indicated chemical properties negatively affected the yield. In stony areas of technogenic landscapes, a positive effect was manifested only by preparations with a maximum proportion of aromatic hydroxide-containing groups (СAr-ОН). Enrichment of humic preparations with microelements (Zn and Cu) did not result in either positive or negative consequences. Conclusion. The use of humic preparations obtained from brown coals for restoring technogenic landscapes is justified only in areas composed of loamy rocks with a low content of humic substances of humus and peat. The noted multidirectional action of humates, which manifests itself depending on their structural and group composition, properties of substrates and plant species used at the biological stage of reclamation, indicates that using the same standardized preparations for the reclamation of various technogenic objects may not be reasonable.