Vol 51, No 9 (2018)

Using the latest version of the international soil classification (WRB 2014/2015) and the classification of soils of Russia (2004/2008), the authors attempted to demonstrate how specific profiles of urban soils in green massifs are classified at different taxonomic levels. The soil profiles were shown in the excursions of the 9th International Conference “Soils of Urban, Industrial, Traffic, Mining and Military Areas” and were discussed by the representatives of national scientific schools. The diversity of the soils studied is determined primarily by the technology of their creation or by the nature of human impact, soil age, properties of the soil-forming rock, and, to a lesser extent, by the type of artificial phytocenosis. By the properties of their profiles, soils are qualified as ones on technogenic deposits (artificial buildings or displaced natural grounds with fragments of soil horizons), buried agrozems and cultural layers. The comparison of two classification systems showed their similarity with respect to the taxonomic level. One can note a similarity of the main solution: are the soils natural or anthropogenic, although the degrees of “anthropogeneity” given in their names may not coincide. The existing differences in the sets of characteristics–qualifiers reflect the genetic trend in the Russian soil classification and strict following the rules in the WRB system.

A classical soil line (SL) in the RED–NIR spectral space is specified by two coefficients “a” and “b.” In this form, it does not characterize soil types and subtypes. A multitemporal soil line (MSL) represents the major axis of the ellipse describing all possible pairs of RED–NIR values characterizing a bare soil surface for a given pixel of remote sensing images. The MSL in the RED–NIR spectral space is specified by several (N) coefficients. The resulting N-dimensional space of MSL coefficients makes it possible to give unique characteristics for each type and subtype of soils in the following zonal soil sequence: soddy-podzolic soils, light gray forest soils, gray forest soils, dark gray forest soils, podzolized chernozems, and leached chernozems. The analysis of variance allows us to state that the soils of this sequence significantly differ from one another in the characteristic sets of MSL coefficients. In other words, these coefficients characterize soil types and subtypes, and the MSL can be considered an empirical soil line (ESL) of the given type and subtype of soil. A classical SL is an integrity of ESLs of different soils within the given scene of remote sensing data.

It is common knowledge that humic substances extracted from different sources are characterized by high biological activity (BA), though the nature of this phenomenon is not quite clear up to now. To expand our understanding of the BA of humic substances, we studied the effect of humates prepared from humic acids of different origin on the germination of seeds. The efficiencies of seed treatment by humate solutions obtained from preliminary purified humic acids extracted from peat, coal, and soil differed insignificantly. At the same time, the solutions of salts of humic substances obtained via alkaline extraction from peat without subsequent purification did not lead to statistically significant biological effects. The analysis of literature and our own data allowed us to conclude that the biological activity of humic acids could be related to their capacity to regulate the growth processes via binding growth inhibitors released into the solution upon seed swelling into the supramolecular complexes.

Determination of the saturated hydraulic conductivity (k_s) is needed in many studies and applications related to irrigation, drainage, water movement and solute transport in the soil. Although many advances are made for direct measurements of k_s, they are usually time consuming and costly. Some attempts have been made to indirectly predict the saturated hydraulic conductivity from the more easily or readily available basic soil properties. The objective of this study was to develop and validate Pedotransfer Functions (PTFs) for estimation of saturated hydraulic conductivity using multiple non-linear regression technique. One hundred and one soil samples were collected from agricultural and forest soils at different depths, at different locations in the Pavanje River basin that lies in the southern coastal region of Karnataka, India. Saturated hydraulic conductivity was measured, by variable falling head method through Permeameter in the laboratory. Prediction accuracies were evaluated using coefficient of determination, root mean square error, mean error, geometric mean error ratio and geometric standard deviation of the error ratio between measured and predicted values. The results show that, the PTFs for the estimation of saturated hydraulic conductivity could be used appropriately for the soils with loamy sand and sandy loam textures falling in this area of the coastal region of southern India.

Urbanozems (Urbic Technosols) contaminated by heavy metals and polychlorbiphenyls (Urbic Technosols Toxic) and intruzems (Urbic Technosols Toxic) were studied in Moscow; additionally, we studied recreazems (Urbic Technosols Thaptohumic) and culturozems (Urbic Technosols Pantohumic) on the territory of the Botanical Garden of Moscow State University (Aptekarskii Ogorod, the Apothecaries’ Garden). In the soils contaminated with heavy metals and oil products, the number of viable cells of bacteria decreased, whereas the content of filterable forms of bacteria increased. The taxonomic structure of saprotrophic bacterial complexes in contaminated urban soils was transformed towards an increase in the diversity of bacterial taxa atypical of natural undisturbed soils. Rhodococci (Rhodococcus genus) predominated in the soils contaminated with oil and polychlorbiphenyls, enterobacteria (Escherichia, Enterobacter, and Klebsiella genera) predominated in the soils contaminated with municipal wastes, and Arthrobacter genus was dominant in the soils contaminated with cement dust. Soils of both Botanical Gardens of Moscow State University were characterized by the high population density and specific distribution of bacteria in the profile; the structure of their saprotrophic bacterial complex had some similarity with that in the soils of more southern regions. The obtained data on the bacterial diversity of urban soils attest to considerable transformation of bacterial communities both in the contaminated urban soils and in the soils of botanical gardens.

Soil fertility is the basis for production of high green mass, which has numerous essential benefits in urban areas. This study aimed to investigate the soil fertility of urban land. This was done by comparing soils from a vegetable garden and its surrounding arable land. A local brickwork dump was included. The soils were Hortisols, slightly stagnogleyic Luvisols, and a Regosol from sandy loamy silt. The location of the study was in the center of one of the world’s largest urban, hard-coal mining and heavy industry areas, the Ruhr area in Germany. The investigations for identifying the characteristic features of the soil fertility involved determination of the profile horizons, texture, pH, bulk density, C/N ratio, content and stocks of organic carbon, total nitrogen, available phosphorus and potassium, and soil water by field capacity. As they are expected to become construction land, the sites were already in a derelict state. The results show that all three soil types had high fertility characteristics. However, the fertility of the garden soils was much greater than that of the local arable land. This was due to the strong and deep accumulation of organic carbon due to compost application. The available phosphorus and potassium contents and field capacity were also distinctly increased in the garden soils. The spatial distribution and distribution with depth of pH, bulk density, organic carbon, nitrogen, available phosphorus, and potassium were extremely heterogeneous among the individual garden soils. In contrast, in the arable land, they were uniform. The organic carbon accumulation in the dump was in the range of that of the garden soils, but the nutrient contents were lower. These results show that the diversity of properties of urban soils is much higher than that of arable soils. The dereliction of arable, garden, and dump soil and vegetation by bushes and trees also affect the soil properties. There should be greater awareness of the high fertility of urban soils, such as vegetable garden soils. Vegetable garden soils have a high potential for contributing to solving urban problems by producing high volumes of biomass and storing water. Therefore, it should be demanded that vegetable garden soils receive a high protection status, and they should not be used for the establishment of construction.

In the territory of the city of Petrozavodsk, the following categories of land use were distinguished: lands of common use, lands of urban and rural development, natural recreation zone, and reserved land. In each area, soil pits were made, and each full profile was analyzed for its morphological structure and physicochemical properties. Among soils, urbostratozems (Urbic Technosols) predominate, urbistratified natural soils (Plaggic Cambisols, Technic Podzols), and technogenic surface formations are spread to a lesser extent. The undisturbed natural soil cover is preserved in suburban forests and on lands of reserve and rural development. The urban soils differ in their physicochemical properties from the zonal natural soils by the elevated base saturation and high content of mineral nutrients. Heavy metal concentrations are mainly at the level of regional background characteristics. Maximum/tentatively permissible concentrations of lead, copper and zinc are exceeded on the lands of common use, building areas, and in the natural recreational zone of the city, which was influenced in the past by the activity of the city-forming plant.

Transformation of particle-size composition, structure, and density of soils upon urbopedogenesis is considered for Rostov agglomeration. Various soils are compared by horizons. It is found that the share of sand fractions increases in upper and middle horizons of migration–segregation chernozems (Calcic Chernozem (Hyperhumic, Loamic)), above all, at the expense of particles of 0.05—0.001 mm in size; with the coarse medium sand fraction 1–0.25 mm being diagnostic for urbopedogenesis. The reason is the introduction of sandy particles upon urban construction, arranging water conduits and other utility lines, as well as the use of icing-control sandy mixtures. The Dolgov-Bakhtin schedule appears to be the most appropriate for assessing the structure of urban soils. Dry sieving testified to the decreasing amount of agriculturally valuable aggregates in all compared pairs of horizons in the sequence of urban soils: under forest vegetation → under steppe vegetation → in the buried massif of urbosoils. The water stability of aggregates decreases in the sequence: soils under steppe vegetation → buried horizons of urbosoils → soils under forest vegetation. The following sequence of urbic horizons (UR and RAT) shows a decrease in the share of agriculturally valuable fractions and an increase in their water stability: heavy-textured UR → light-textured UR → RAT. The density of natural soils varies insignificantly within the city territory, with its urbostratified soils (Calcic Chernozem Novic (Technic Loamic) in residential areas often manifesting the maximal density.