The analysis of peculiarities of applied use of soil data has been carried out. It is shown that most of practical tasks require spatial information about soils and their properties. In this regard, a soil map is considered as a kind of interface between theoretical and applied soil science. The disadvantages and limitations of modern soil maps, which significantly reduce the possibility of their practical use, have been revealed. The analysis of possible ways of overcoming the revealed limitations has been carried out. It is established that increase of practical importance of soil science at present is impossible both without technological modernization of soil mapping and without semantic, methodological adjustments. The complete transition from traditional soil maps to pixel spatial soil databases is necessary and already possible. Information load and accuracy of soil maps can and should be increased due to transition from mapping of soil position in one or another classification to mapping of individual, agriculturally important soil properties. In order to solve practical agricultural problems it is important to complete the information of soil maps with information about modern processes occurring in soils, which can be obtained from spatial digital modeling.

The influence of climate aridization on soil salinity in the basins of the south of Eastern Siberia and Mongolia is considered in the article. The data characterizing the climate aridity of the basins of the south of Eastern Siberia over 50 years are analyzed. In the south of Eastern Siberia from 1955 to 2015, the increase in air temperature was higher than in the whole world. In the basins of Tuva, the increase in air temperature was 2.5–3.7 ^оС; in the Minusinsk depression – 1.7–2.8 ^оС, in the basins of Buryatia – 1.5–1.8 ^оС; the coefficient of determination for moving averages over 20 years (R²) was 0.9–0.95, the changes are significant – Student's criterion 19–35. Changes in the aridity coefficient were in the range of 0.02–0.14; according to the Student criterion, they were significant (t = 7.4 – -22), while a decrease in aridization was observed in the Minusinsk depression and its growth in other regions. Thus, in general, for the studied regions, the multidirectionality of the processes of climate aridization has been ascertained. In the Minusinsk depression, despite a slight decrease in aridization, category changes (according to the classification of Lobova et al., 1977) did not occur during this period, the territory remained in the arid and subarid categories. Despite the increase in climate aridization in the basins of Tuva and Buryatia, most of them also did not show a tendency to more arid category. Nevertheless, in a number of hollows in the south of Eastern Siberia, an increase in aridization with a transition to a more arid category was observed. This applies to the Eravnensky and Barguzinsky basins of Buryatia, which switched from weakly arid to subarid, as well as to the Ubsunur basin of Tuva, which turned from arid to strongly arid. For the basins of the south of Eastern Siberia, where climate aridization was recorded, the question arose about the possible activation of the process of soil salinization. To solve this problem, materials were collected on soil salinity in the arid regions of Mongolia. It was found that an increase in climate aridity even in the extreme arid deserts of the Gobi, where parent rocks are not saline, under automorphic conditions, the soil is practically not saline (the amount of salts does not exceed 0.1%). In areas where saline Cretaceous-Paleogene red sediments are spread, automorphic soils are saline, and the amount of salts may exceed 2.5%. Thus, in extremely arid climatic conditions, salinization of automorphic soils can range from non-saline to highly saline. Under the hydromorphic conditions of the basins of the south of Eastern Siberia, as well as in Mongolia, climate aridization inevitably leads to an intensification of the salt accumulation process, therefore, in the basins of Tuva and Buryatia experiencing climate aridization, a process of soil salinization in hydromorphic landscapes should be expected.

V.V. Dokuchaev Soil Science Institute has initiated a project on compilation of a new Digital Soil Map of Russia on the basis of the Soil Map of the Russian Federation (SMRF) 1 : 2.5 M scale (1988) revised and interpreted in ideology and nomenclature of the new substantive-genetic Classification System of Russian Soils (CSRS). The first stage implies the conversion of soil mapping units on the original map into the CSRS with a corresponding renaming of soils in the attribute database to the digitized version of the map for each soil polygon. During the second stage, a new digital model of the soil cover is developed with the use of digital soil mapping technologies, basic soil map, and new materials, including satellite images and digital elevation models. The legend section “Tundra Soils” contains 16 soil units forming their own areas or found in various combinations (soil complexes). As a result of the reclassification and careful analysis of each soil polygon, the soils of Arctic and Subarctic tundra have obtained a more detailed and differential representation on the new map, and their diagnostics based on the morphology of the profiles and major soil properties have been specified. The most significant changes in the initial content of the map concern the soils referred to as gley soils on the SMRF. A separate group of cryozemic soils has been specified. Weakly developed soils (petrozems, psammozems, and pelozems) and lithozems have been introduced on the map for the first time. Differential decisions are suggested for the soils of “spotty tundra” with sorted and nonsorted circles and for the soils of cryogenic fissures and cracks. The results of the study have made it possible to refine the diagnostics and nomenclature of soils in the CSRS.

The sessile drop method was used to measure the contact angle of wetting (CA) of ordinary Chernozem from the fields of the Kamennaya Steppe agrolandscape used in various ways. The treatments differ in the intensity of tillage operations (protected mowed steppe, arable land after moldboard plowing), the use of mineral fertilizers and their aftereffect, as well as changes in soil properties under the influence of irrigation. At the same time, the total organic carbon content, C/N ratio, specific surface area, and rheological parameters were determined for the physical and chemical characteristics of soils. The results of the study showed that the hydrophilic-hydrophobic properties of the surface of the solid phase of soils, which largely determine the main structure-forming properties of soils, can be characterized by the value of the wetting edge angle. The CA of the studied soil samples varies from 32 degrees (highest wettability) to 45 degrees (lowest wettability). The lowest wettability is due to the increased content of hydrophobic compounds in the organic matter of soils and is characterized by the highest CA and is typical for native, untreated soil of the mowed steppe, which differs from other studied variants of the experiment in all explored physical and chemical parameters. Moldboard plowing as well as fallowing lead to changes in the physical and chemical properties of the soil and the qualitative composition of organic matter in the direction of their deterioration and a decrease in the CA. The use of mineral fertilizers contributes to the increase in the studied indicator mainly due to changes in plant productivity, in particular, the differences in CA are due to the impact of root secretions and plant residues on the soil properties. For the studied soils, the CA changes in the following series: mowed steppe > arable land with the mineral fertilizers application > arable land undergone the aftereffect of fertilizers. Correlation analysis revealed the relationship of CA with organic carbon content, specific surface area, and rheological characteristics of Chernozems. Thus, CA can serve as an integral indicator of changes in the physical and chemical properties of soils, their degradation changes under the conditions of different agricultural load. The method used in this research for determining CA requires a smaller amount of sample compared to rheological methods and is generally more informative than determining the content of organic matter.

In soils of Ili Alatau (dark kastanozems, light kastanozems, mountain chernozems) both in continuous cropping system of sugar beet and in crop rotation with prolonged use of fertilizers the soil agrochemical indices, phosphorus reserves and group composition (total, organic and mineral) vary significantly. The total phosphorus content in the soils was 1720–2330 mg/kg and decreased in the series: virgin mountain chernozems > arable dark kastanozems > arable mountain chernozems > light kashtanozems > virgin dark kastanozems. It was observed, that in arable dark kastanozems, as compared to virgin soils, the content of available forms of phosphorus (loose-bound phosphates Ca-PI and miscellaneous calcium phosphates Ca-PII) increased, and the content of plant unavailable forms of phosphorus (poorly soluble Ca phosphates Ca-PIII, phosphates of aluminum Al-P and iron Fe-P) decreased. In arable mountain chernozems, in comparison with virgin mountain chernozems, the content of all fractions of phosphorus decreased. Arable light kastanozems contain the least amount of available phosphates and the highest of phosphates of aluminum and iron. When cultivating beets on light kastanozems, the content of all fractions of phosphorus, except iron phosphates, increased with increasing dose of fertilizers. The effectiveness of the application of the organic-mineral fertilizers was comparable to the introduction of NK + P_1.5 and NK + P₂, the yield of sugar beet in the crop rotation in these variants is the highest and amounts to 614 and 577 centner/ha; in the control value (obtained without fertilizers) – 197 centner/ha, and in the variant with application of only NK fertilizers – 277 centner/ha. In continuous cropping system these values were 576 and 561 centner/ha; 311 and 327 centner/ha respectively. Close values of crop yield were obtained in two variants: with the organo-mineral system and NK + P_1.5, due to the additional use by the plants of sugar beet phosphorus of newly formed organic compounds.

A comparative analysis of the mineralogical composition of the clay fraction (< 1 μm) of chestnut soil and solonetz has been performed in the article. Soils were studied in the oldest part of the Caspian lowland in north-west where the microrelief is not quite apparent (microdepressions no more than 5–10 cm depth), but with a contrast soil cover. The content of silt fraction in chestnut soil varies from 25.6 to 33.9%, in the solonetz – from 11.7 to 51.6%. In all horizons of the compared soils, except for the upper surface horizons (SEL, AU1), mixed-layered minerals dominate (39–52% in the fraction) over illite (27–37% in the fraction). In the surface horizons illite (48%) dominates over mixed-layer minerals (35%). The compared soils have some similarities in their crystal-chemical state: the imperfection of the kaolinite structure and the superdispersed state of the mixed-layer phase in the upper horizons, as well as the appearance of individual smectite and chlorite packets in the mixed-layer phase in the lower horizons (BC, C). The degree of perfection of the kaolinite structure both in the solonetz and in the meadow-chestnut soil increases towards the bottom of the profiles. The obtained data allow suggesting that in the meadow-chestnut soil the clay phase retained traces of the solonetzic stage of soil formation.

Analytical data show that prolonged extensive agricultural use of typical Chernozem of Kursk region (Haplic Chernozem) results in adverse changes in some soil properties. This primarily concerns the humus content and the structural state of the Chernozem. Under the influence of continuous winter wheat growing (for 54 years) the losses of humus made up 24% of its content in virgin soil. The permanent corn growing (for 54 years) led to humus 32% losses, and under the influence of the bare fallow (for 54 years) – 48%. As a result of mineralization of humus, which is one of the main aggregative agents, water resistance of Chernozem structure has deteriorated. The number of water-resistant aggregates in variants with continuous winter wheat and continuous corn decreased in comparison with virgin soil (by 30% and 39% respectively). In terms of water resistance, the structure of Chernozem was transformed in agrocenoses from “extremely high” to “good”. Under the influence of the bare fallow the content of water-resistant units decreased by 75%, and the structure became “non-water resistant”. At the same time, the average diameter of waterproof aggregates decreased 2.8, 3.6 and 4.8 times in variants with continuous winter wheat, corn and permanent bare fallow, respectively, whereas the content of the water peptized clay increased 2.8–4.7-fold, and pH of medium increased by 0.16–0.57. At the same time, the content of soil exchangeable calcium reduced (more than 1.1-fold), as well as hydrolytic acidity (1.1–1.7-fold), the content of organic forms of phosphorus (1.1–1.4-fold) and the ratio of organic forms of phosphorus to mineral ones also decreased 2.1–4.1-fold. When the bare fallow is transferred to the abandoned land, the properties of Chernozem vary with different intensity. The most significant changes occurred with water-resistant aggregates. Their content has increased by 53% over 20 years, and the structure has transformed from “non-water resistant” to “good”, while the content water peptized clay has decreased 2.1 times. During the 20-year period, the content of exchangeable calcium and hydrolytic acidity increased by 1.9 and 1.03 mg-eq/100 g of soil. The content of humus has increased by 0.78%, i. e. humus content restoration occurred with a speed of only 0.04% per year. It is necessary to consider this factor when regulating the humus status of the plowed and eroded soils. In general, the impact of continuous bare fallow on the properties of Chernozem was so profound that 20 years after its transfer to the category of abandoned lands, the properties of Chernozem, in most cases, have been restored only to the level typical of variants with crop cultivation.

V.M. Fridland (1919–1983) – distinguished Soviet pedologist-geographer and cartographer, graduated from Moscow State University, Doctor of geographical sciences, Professor, laureate of the Dokuchaev Prize of USSR Academy of Sciences. He developed the doctrine of the structure of soil cover. Editor-in-chief and author of Soil maps: RSFSR, scale 1 :2 500 000 (1988); Educational Soil Map of the World, scale 1 : 15 000 000 (1984). One of the first Russian soil researchers of humid and arid tropics and subtropics, author of the USSR soil classifications, and of a number of books on soils.