Dynamics of the microaggregate composition of chernozem in relation to changes in the content of organic matter

Abstract

Monitoring of soil dispersivity and humus state has been performed in the stationary profile of ordinary chernozem in the Botanic Garden of the Southern Federal University in 2009-2014. The contents of physical clay and sand are almost stable in time, which indicates a quasi-static (climax) equilibrium in the soil. Another (reversible dynamic) process occurs simultaneously: seasonal and annual variation in the mass fractions of clay and silt in physical clay. Variations of humus content in the whole soil and in its physical clay are also observed on the background of seasonal changes in precipitation and temperature. A procedure has been developed for the analysis of the polydisperse soil system with consideration for the quasi-static and dynamic equilibriums. A two-vector coordinate system has been introduced, which consists of scales for changes in the contents of physical clay and physical sand in 100 g of soil and changes in the fractions of clay and silt in 100 g of physical clay. Co-measurements of two dispersivity series of soil samples-actual dynamic and calculated under quasi-static equilibrium (ideal)-have been performed. Dynamic equilibrium coefficients, which cumulatively reflect the varying proportions of physical clay and physical sand in the soil and the mass fractions of clay and silt in physical clay, have been calculated.

Current State of Haplic Chernozems in Specially Protected Natural Areas of the Steppe Zone

“…The analysis of organic 368 matter content in Haplic Chernozems in Botanical Garden in different years showed, that the organic matter content decreased on 0.37% since 1953 to 2014 (Table 3). At present, the Haplic Chernozems in Botanical Garden are at the restoration stage (Kryshchenko et al, 2016). In the Haplic Chernozems of the Reserved Fallow land and Persianovskaya Reserved Steppe with the full reservation conditions since 1953 year no changes in the organic matter content were noted (Table 3).…”

“…The chernozems of the Persianovskaya Reserved Steppe and the Botanical Garden have relatively high contents of silt (the particle with size <0.001) ( Table 4). The silt fractions of Haplic Chernozems contain four groups of clay minerals: kaolinite, chlorite, hydromica and smectite minerals (Kryshchenko et al, 2016). In the clay fraction (the particle with size 0.05-0.001) of the soils, the content of hydromicas increases by 10−19% compared to the clay fraction and that of smectites decreases.…”

“…Such are the regional biogeochemical features of the soil microelement composition in Rostov region and of the mineralogical composition of the parent rocks. The yellow-brown loess-like loams and clays of the Pre-Caucasian Plain inherited the stable minerals of the initial rocks with the typical microelement composition of the minerals (Kryshchenko et al, 2016;Minkina et al, 2017a). The lighter texture of the Haplic Chernozem in the Reserved Fallow land "Priazovskaya Steppe" is due to the increased content of SiO 2 compared to the other soils under study.…”

Soil physical and chemical properties changes after zinc contamination

“…The saturation degree of physical clay with clay (V α , %) was calculated by the Kryshchenko method (Kryshchenko et al, 2016):…”