Agriculture in the Baksan Gorge of the Central Caucasus, Kabardino-Balkaria, Russia

No agriculture is possible without soil. This article reviews available data on the soils of the Baksan Gorge located in the Kabardino-Balkarian Republic, Russia. The research objective was to collect and analyze information on the soil composition and crop yields in this region of the Central Caucasus. The review covered the last five years of scientific publications cited in Scopus, Web of Science, and Elibrary. It also featured contemporary and archival documents on the soil composition and periglacial agriculture in the Baksan Gorge. The agriculture and cattle breeding started in the Central Caucasus in the first millennium BC when the local peoples began to develop these lands as highland pastures and, subsequently, for agricultural farming. During the second millennium BC, crop production became one of the most important economic sectors in the Central Caucasus. Corn, barley, wheat, and millet were the main agricultural crops in the Baksan Gorge. Millet has always been a traditional Kabardian crop, and millet farming occupied the largest flatland areas. Barley was the staple crop in the highlands. Currently, the list of local staple crops includes corn, wheat, and sunflower. Barley, oats, peas, potatoes, vegetables, berries, nuts, grapes, and annual herbs are also popular. The past fifteen years have seen an extensive development of intensive horticulture in the Baksan Gorge. Agricultural ecology and production problems depend on the localization of agriculture in the Central Caucasus. This research reviewed data on the effect of soil composition on the yield and value of agricultural crops in the Baksan Gorge of the Central Caucasus.

Microbiome composition of disturbed soils from sandy-gravel mining complexes with different reclamation approaches

Activities connected to mineral mining disrupt the soil layer and bring parent rock material to the surface. It leads to altering the environmental conditions and leaves behind vast areas of disturbed lands. Returning these lands to natural ecosystems is an important contemporary challenge, which can be acquired by reclamation practices. Soil microbiome composition reflects changes happening to disturbed lands; thus, its analysis is a powerful tool for evaluating the disturbance degree and estimating the effect of the implementation of reclamation techniques. Additionally, factors connected to the characteristics of a particular geographical region have a certain impact on the microbiome and should be taken into account. Thereby, studies of soil microbiomes of disturbed soils of different origins are essential in understanding the dynamics of soil restoration. Here, we focus on soil microbiomes from two sandy-gravel mining complexes in mountainous areas with a moderate continental climate of the Central Caucasus. These quarries share the same parent rock material, but differ in benchmark soil type and reclamation approach - one was left for passive recovery and the other was technically reclaimed with overburden material. Comparative analysis of microbiome composition, based on sequencing of 16S rRNA gene libraries, showed that region and disturbance are the key factors explaining microbiome variation, which surpass the influence of local factors. However, the application of reclamation techniques greatly reduces the dissimilarity of soil microbiomes caused by disturbance. Linking of soil chemical parameters to microbiome composition showed that the disturbance factor correlates with a lack of organic carbon. Other chemical parameters, like pH, ammonium, nitrates and total carbon explain microbiome variability on a smaller scale between sampling sites. Thus, while regional and disturbance factors reflected differentiation of soil microbiomes, soil chemical parameters explained local variation of certain groups of microorganisms.

Cryoconites as biogeochemical markers of anthropogenic impact in high mountain regions: analysis of polyaromatic pollutants in soil-like bodies

The globalisation and omnidirectional character of anthropogenic processes has challenged scientists around the world to estimate the harmful effects of these processes on ecosystems and human health. Polycyclic aromatic hydrocarbons (PAHs) is one the most infamous group of contaminants, originated both from natural and anthropogenic processes. They could transport to high latitudes and altitudes through atmospheric long-distance transfer and further enter ecosystems of these vulnerable regions by deposition on terrestrial surfaces. An interesting object for tracking transboundary contamination processes in high mountain ecosystems is called cryoconite. Cryoconite, a dark-coloured supraglacial sediment which is abundant in polar and mountain environments, is considered as a storage of various pollutants, including PAHs. Thus, it may pose a risk for local human health and ecosystem through short-distance transfer. Studied cryoconite sediments were collected at the surface of Skhelda and Garabashi glaciers, Central Caucasus high-mountain region, as well as mudflow, moraine material and local soils at the Baksan Gorge in order to examine levels of their contamination. We analysed the content of 15 priority polyaromatic compounds from the US EPA list and used the method of calculation of PAHs isomer ratios with the purpose of identifying their source. To estimate their potential toxicity, Benzo[a]pyrene (BaP) equivalents were calculated. Maximum concentration was defined for NAP (84 ng×g-1), PHE (40 ng×g-1) and PYR (47 ng×g-1), with the minimum concentration for ANT (about 1 ng×g-1). The most polluted material is a cryoconite from Garabashi glacier because of local anthropogenic activities and long-distance transfer. High-molecular weight PAHs are dominated in PAHs composition of almost all samples. The most common sources of PAHs in studied materials are combustion processes and mixed pyrolytic/petrogenic origin. Toxicity levels of separate PAHs did not exceed the maximum permissible threshold concentrations values in most cases. However, the sum of PAHs in BaP equivalents exceed the threshold values in all samples, in some of them more than twice.

The current state of mountain meadow soils of subalpine pasture ecosystems of the Central Caucasus (elbrus altitudinal zonality)

Intensive recreational, agricultural and logistics land use in uplands leads to their transformation and degradation. Subalpine meadow ecosystems of Central Caucasus are traditionally used for grazing and mowing. The work determined the current state of soils on pastures (mountain meadow-steppe subalpine soil and mountain meadow subalpine soil) and the level of changes of their properties under different stages of pasture degradation were defined. The efficacy of 4-stage assessment system for evaluating the pasture degradation of grasslands dominated by Bromus variegatus M. Bieb. was shown for the assessment of soil cover condition. The reduce of estimated soil indicators and degradation of soils under pastures with maximal degradation stage (DS3) of meadow ecosystems was statistically significant.

Geochemical and microbiological features of cryoconite, sampled from glaciers of the Central Caucasus region (Kabardino-Balkarian republic, Russia)

Determination of geochemical and microbiological properties of the cryoconite, related types of sediments and periglacial soils is essential to investigate impact of glaciers on terrains development at the Central Caucasus region. The studied sediments were sampled at the Garabashi and Skhelda glaciers as well as in vertical sections of local soils at the Baksan gorge. Sampled materials were investigated in terms of physicochemical parameters and nutritional state. The trace elements concentrations (Cu, Pb, Zn, Ni, Cd) were also evaluated in samples selected. The data obtained shows much higher content of organic carbon in soils (up to 7.82%) in comparison with cryoconite (max. 1.63%) due to the effect of superficial vegetation cover, however, rates of microbial activity were similar between some samples of sediments and soils. The analysis of the particle size distribution shows a similarity of the studied materials: in almost all samples, there is a dominance of the sand fraction. Cryoconite sediments on both of the above-mentioned glaciers are found as enriched with phosphorus, essential values of potassium (298 mg/kg in K2O units) and ammonium nitrogen (N-NH4 - max. 247 mg*kg) are identified at Garabashi glacier which could be a result of long-distant transfer and anthropogenic activity. The highest content among trace elements was identified for Zn (62 mg*kg for cryoconite and 60.5 mg*kg for soils), the most contaminated materials were sediments from Garabashi glacier and Entisols, up to moderate level, which is mostly associated with anthropogenic activity. Thus, development of tourism in the Central Caucasus, which is mostly associated with construction and transport, affects the pollution status of supraglacial sediments and periglacial soils as well as their agrochemical and microbiological features.

Biological activity of mountain meadow subalpine soils of Central Caucasus

Indicators of biological activity (humic content and stock, Cmic content and stock, hydrolytic and redox enzymes activity) were measured for the first time in the upper horizons of mountain meadow subalpine soils of Central Caucasus (elbrus altitudinal zonality in Kabardino-Balkaria). The comparative assessment was performed for the biological characteristics together with soil density and acid-base properties for soils of natural and pasture ecosystems. The integral index of ecological and biological soil state (IIEBSS) was calculated to estimate the level of changes in biological activity. It was shown that pasture degradation leads to 30% decrease of IIEBSS compared to the undisturbed soil. The defined biological parameters of natural undisturbed mountain meadow soils could be used as diagnostic indicators for the ecological studies of ecosystems under anthropogenic load.