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Munsell Soil Colour Charts are widely used by soil scientists as the most unbiased way for determining the colour of soil samples. However, there are only a few studies on the variance in people's assessment of the colour of soil samples on this scale and the factors that determine this variance. In this work, we analyze the colour estimates of > 100 undisturbed soil samples by 20 people. For diverse soil samples collected from Anthrosols, Arenosols, Histosols, Podzols and Retisols at the Smolenskoye Poozerye national park, the fraction of votes that support the mode differs from 0.15 to 0.63 with mean of 0.29. The agreement of people’s estimates is significantly less pronounced for hue than for value (p = 0.0001) and chroma (p = 0.002) in dark and muted, but not in light and saturated samples. On average, females vote for mode in more fraction of samples than males (p = 0.026). Moreover, there are people who vote for and against mode more frequently that it is expected by chance. Within-sample variances of estimates calculated after conversion into RGB and CIELAB systems correlate weekly with uncertainty of estimates calculated as fraction of votes that do not support the mode. Soil horizons have different variances in colour estimates. The uncertainty in colour estimation with a Munsell Soil Colour Chart is highly dependent on both sample characteristics and people. The agreement between participants in colour assessment increases substantially when neighboring Munsell chips are treated as equal.

In this study, we discussed relationship between the vertical and spatial differentiation of 14 chemical elements (total content and three mobile fractions extracted by NH4 Ac, NH4 Ac with 1% EDTA and 1M HNO3 ) and the environmental factors in background Retisols and Stagnosols within a soil catena. In the A soil horizon, the extractability of elements decreased in the series Cd, Mn, Pb> Co, Ni, Cu, Fe> Zn, Bi, As> U, Cr, Mo> Sb. In the O and A horizons, total and exchangeable Mn and Zn were uptaken by plants. In the A horizon, total Bi, Cd, Pb, Sb, Mo, exchangeable As, Bi, Cd, Co, Ni, Mo, as well as As, Cd, Cu, Pb, Zn, Sb bound with Fe-Mn (hydr)oxides were sorbed by soil organic matter; Cr, Fe, Mn formed the organic complexes. In the C horizon, Cd, Fe, Mn, Sb complexes co-precipitated with carbonates. In the Bt horizon, total Cr, Cu, exchangeable Cu, Ni, as well as Cr and U bound with Fe-Mn (hydr)oxides migrated due to the lessivage. On the toeslope’s biogeochemical barrier, exchangeable Zn, Mo bound with complexes, As, Bi, and Fe bound with Fe-Mn (hydr)oxides were accumulated. In the lower part of the catena, peat accumulated the exchangeable compounds of As, Bi, Cr, Fe, Mo, Pb, U. The spatial differentiation of elements became less contrasting from the O and A horizons to the E, B and C horizons.

Abstract The gradual drying up of saltwater bodies creates habitats that are characterised by changing environmental conditions and might be available only for a subset of plants from the local flora. Using two terrestrial areas with different ages on the Caspian Coast as a chronosequence, we investigated factors including microtopography, ground water level and soil salinity that drive plant community succession after the retreat of the sea. Vegetation of the two key sites appearing after the retreat of the Caspian Sea about 365 and 1412 years ago were compared in terms of both evolutionary and ecological traits of plants. Both edaphic conditions and vegetation differed between the two sites with harsher edaphic conditions and more xerophytes on the elder site. Species that grew only in the ‘early’ site were dispersed across the phylogenetic tree, but their loss on the 'late' site was not random. Species that grew only on the 'late' site were phylogenetically clustered. On the level of microtopography, elevated spots were more densely populated in the ‘early’ site than lowered spots, but on the 'late' site the situation was opposite. The main edaphic factors that drive the difference in vegetation composition between the two sites are likely salinity and moisture. During environmental changes, different plant traits are important to survive and to appear in the community de novo. Microtopography is important for forming plant communities, and its role changes with time.

Understanding the rate and direction of pyrogenic succession in arid ecosystems, which depends on many factors, including the intensity of grazing and the frequency of pyrogenic expo-sure, will allow for more accurate predictions of the consequences of fire onplant communities, and will assist with better fire management. We studied the vegetation on 55 sites in and near the “Chernye Zemli” Natural Biosphere Reserve that burned at different times or were not affected by fires over the past 35 years and characterized the changes in vegetation cover associated with the impact of wildfire and grazing. The descriptions were grouped into chronological stages according to the time elapsed since the last fire, or into groups according to the frequency of fires. In pairwise comparison of the projective cover of plant species between chronological stages, it correlated most strongly between successive initial stages (for stages 1 and 2, p = 0.003, r = 0.73; for stages 2 and 3, p < 0.001, r = 0.78). Species with an initially higher projective cover were more likely to grow on plots in the first year after the fire: p < 0.03. Plots with rare and frequent fires had similar projective cover of individual species (r = 0.64, p < 0.001). We conclude that in the course of pyrogenic succession, communities are gradually replaced over at least ten years. At the same time, the composition of a plant community at the initial point of succession depends on the prevalence of species in the community before the fire. No fundamental effect of the frequency of fires on the composition of plant communities has been revealed.

The soil response to a jet-fuel contamination is uncertain. In this article, original data on the influence of a jet-fuel spillage on the topsoil properties are presented. The data set is obtained during a one-year long pot and field experiments with Dystric Arenosols, Fibric Histosols and Albic Luvisols. Kerosene loads were 1, 5, 10, 25 and 100 g/kg. The data set includes information about temporal changes in kerosene concentration; physicochemical properties, such as рН, moisture, cation exchange capacity, content of soil organic matter, available P and K, exchangeable NH4+, and water-soluble NO3–; and biological properties, such as biological consumption of oxygen, and cellulolytic activity. Also, we provide sequencing data on variable regions of 16S ribosomal RNA of microbial communities from the respective soil samples.

In rural areas, research on the environment in native (untaught) soils is important to understand the rate of pedogenesis and to prevent the problems associated with hidden huger. In this article, original data on vegetation, chemical properties and elemental and mineralogical composition of Kastanozems (Protosalic, Siltic) and Hypersalic Solonetz (Siltic) of the small gully catchment (2 ha in total) located at the NE Ergeni Upland (Western Kalmykia, Russia) were presented. Vegetation was described and cut off (to characterize an aboveground biomass) at 13 key plots of 1 × 1 m. The list of species of the small gully catchment area amounts to 23 species (predominantly, perennial herbs) belonging to 13 families and 11 orders. The main dominants are Artemisia lerchiana, A. austriaca, Festuca valesiaca and Poa bulbosa. Soils were described and sampled in 11 cross-sections and two key plots (0 – 10 cm topsoil sampling). In soil water extracts (79 samples in total), electrical conductivity (EC) and pH were measured. In soil samples, particle size distribution, soil organic carbon and CaCO3 contents, total concentration of all the macro elements, some trace (Cl, Nb, Rb, Th, Y, Zr) and potentially toxic elements (As, Co, Cr, Cu, Ni, Pb, Sr, V, and Zn) were described. Moreover, the concentration of three mobile fractions of elements (Li, Be, B, Na, Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Ba, Cd, Pb) measured using Inductively Coupled Plasma Atomic Emission Spectrometry (AES-ICP) was presented. Geochemical indexes of weathering (R – Silica/Alumina, CIW – Chemical Index of Weathering, CIA - Chemical Index of Alteration, WIP – Weathering Index of Parker, PWI –Product of Weathering Index, Vogt Ratio, PIA – Plagioclase Index of Alteration, STI – Silica-Titanium Index, B/A – Bases/Alumina, B/R – Bases/R2O3, Si/R - Silica/R2O3, Weathering indexes WI-1 and WI-2, Si/Ses – Silica/Sesquioxides, Si/Fe – Silica/Iron, a – Potassium/Sodium, ba-1 – (Potassium-Sodium)/Alumina, ba-2 – (Calcium-Magnesium)/Alumina, Ba – (Potassium-Sodium-Calcium)/Alumina) were calculated. In 12 bulk soil samples from Kastanozems and Solonetz, mineralogy (X-Ray diffractometry, the Rietveld full-pattern fitting method for quantitative analysis) was described. Data obtained can be used for more confident identification of pollution sources and pollutants’ migration routes, as well as for more effective land-use management, calculating the required doses of nutrients and for adaptation of land use.

The article presents protocols for determining the biological activity of kerosene-contaminated soils in terms of two indicators, i.e. cellulolytic activity and biological consumption of oxygen. A method for determining the cellulolytic activity of soils is based on measuring the rate of cellulose decomposition in situ. Model test objects (linen fragments 10 × 20 cm weighing 4–6 g) were put in the root layer of soil. A month later, the linen was removed from soil and its weight loss was measured. Cellulolytic activity was estimated by the weight loss of readily hydrolysable organic matter (RHOM) per day (mg/g RHOM per day). The method for determining the biological consumption of oxygen of water was adapted for soils. The indicator characterizes the ability of microorganisms to oxidize organic substances using oxygen for 5 days. The analytic procedure includes taking a soil sample, preparing the suspension (the ratio of soil to distilled water is at least 1:10) and after 5 days measuring the concentration of unspent dissolved oxygen using the oxygen meter. The proposed methods give reproducible and reliable results on the biochemical activity of soil microorganisms in a wide range of soils, e.g. Retisols, Arenosols and Histosols, including those under hydrocarbon pollution.

One of the most important challenges for soil science is to determine the limits for the sustainable functioning of contaminated ecosystems. The response of soil microbiomes to kerosene pollution is still poorly understood. Here, we model the impact of kerosene leakage on the composition of the topsoil microbiome in pot and field experiments with different loads of added kerosene (loads up to 100 g/kg; retention time up to 360 days). At four time points we measured kerosene concentration and sequenced variable regions of 16S ribosomal RNA in the microbial communities. Mainly alkaline Dystric Arenosols with low content of available phosphorus and soil organic matter had an increased fraction of Actinobacteriota, Firmicutes, Nitrospirota, Planctomycetota, and, to a lesser extent, Acidobacteriota and Verrucomicobacteriota. In contrast, in highly acidic Fibric Histosols, rich in soil organic matter and available phosphorus, the fraction of Acidobacteriota was higher, while the fraction of Actinobacteriota was lower. Albic Luvisols occupied an intermediate position in terms of both physicochemical properties and microbiome composition. The microbiomes of different soils show similar response to equal kerosene loads. In highly contaminated soils, the proportion of anaerobic bacteria-metabolizing hydrocarbons increased, whereas the proportion of aerobic bacteria decreased. During the field experiment, the soil microbiome recovered much faster than in the pot experiments, possibly due to migration of microorganisms from the polluted area. The microbial community of Fibric Histosols recovered in 6 months after kerosene had been loaded, while microbiomes of Dystric Arenosols and Albic Luvisols did not restore even after a year.