Micromorphological soil assessment in abandoned quarry dumps of the Central Caucasus, Russia

Abstract

This study compared the micromorphological and agrochemical metrics in soils from the quarry dumps and zonal soils, the Central Caucasus. Soil micromorphological investigations are important tool for evaluation of soil dynamics after anthropogenic impacts on terrestrial ecosystems. The results showed that the carbon content in the primary soil of the sand and gravel quarries was lower than that in the reference soil. The differences detected were statistically significant for both the Urvan plot soils (t = 11.95; p = 0.000) and the Progress plot soils (t = 18.73; p = 0.000). In contrast, in the quarry with clay bottom substrate (Gerpegezh), no significant difference was found between the reference and postmine soils. The reference soil around the sand and gravel quarries was slightly more acidic than the primary soil. In the clay quarry, the primary soil was more acidic with a strong acidic value, while the reference soil was neutral. The difference of nutrients (P, K, NH4+, NO3-) between the primary and reference soils were negligible. The only exception was the NO3- content in the reference soil of Progress settlement, where it was significantly higher (t = 4.19; p = 0.002) than in the original soil of the site. No difference was observed for the mineral component of the primary soil. Investigation of key zonal soils of the region. Zonal Caucasus soils: Phaeozem Gleiyc, Phaeozem and Umbric Retisol are different in terms of micro texture. Thus, Phaeozem Gleiyc characterizes by microstructure composed by primary angular mineral forms. Phaeozem and Retisol demonstrated formation of biogenic structure with alteration of mineral particles. Data obtained show that rapid self revegetation of the quarries results in initialization of primary soil formation and transformation of the soil microstructure and organization on the micro level.