Articles

Th e article discusses the current approaches to the assessment of the heterogeneity of soil properties. On the example of the experimental plot (106 ha) of the RUNE “Grodno Zonal Institute of Plant Industry of the National Academy of Sciences of Belarus” it is shown that ignoring the intra-fi eld heterogeneity leads to even more signifi cant diff erences. On the experimental fi eld, using satellite images and multi-temporal indices EVI, microplots with an area of 50 to 200 m2 with а signifi cantly reduced level of eff ective fertility, up to the death of plants, were identifi ed, on the basis of which а sampling grid was developed. During the fi eld work, 214 pHKCl samples were taken with а sampling step of 70 m and 53 additional samples in the “problem areas”. Using geostatistical methods, data on the spatial heterogeneity of pHKCl were obtained, the degree of spatial dependence and the accuracy of the results obtained were estimated for various numbers of samples (107, 216, and 268 points). Further use of stochastic modeling made it possible to construct high-precision cartograms of acidity with а pixel resolution of 4 m and 12 m. We also showed that the use of cell sizes less than the processing device is not useful for solving applied issues of precision farming. Probabilistic-statistical models were obtained, represented by cartograms of mean square errors and the probability of the phenomenon. Th e resulting cartograms showed the presence of ultra-acidic soils in the “problem zones”; such а reaction also determines the presence of toxic aluminum compounds and extremely low calcium and magnesium contents, which jointly lead to the absence of seedlings of cultivated vegetation. А detailed accounting of soil acidity in comparison with а classical agrochemical survey provided savings of $ 2807 by the application of СаС03, which made it possible to fully compensate for the additional costs of taking and analyzing а larger number of samples.

The regularities of the spatial distribution of ¹³⁷Cs in forest soil at the microlandscape level in semiromophic and hydromorphic conditions in the Bryansk region at different measurement steps with the KORAD radiometer (10, 2 and 0,5 m) are investigated. The variability of the ¹³⁷Cs stock obtained by two devices differing in the size of the sampling area (RPO) is compared: 1) CORAD radiometer 2) sampler D=14 cm. The ratio of the variability of the ¹³⁷Cs distribution obtained by field radiometry to the sampling data (CVcorad/CV sample) for the entire site is 0,63; for the hydromorphic part, B1-1 is 0,87. For the entire site (size 50x80 m), a weak spatial correlation was revealed (the effect of a "chessboard"), for a local hydromorphic site, a strong correlation with a rank of 1,4 m.

The aim is to present statistical portrait of soil cover pattern for farm as series of cumulative statistical distributions of soil horizon’s depth and thickness. The object is soil combinations of Haplic or Luvic Protosodic Kastanozems and Solonetzs at the experimental station “Irrigated” localized in southern-western end of the Volga Upland near the Volga-Don Channel. Majority of empirical statistical distributions of soil horizon’s depth for general data fetch (182 profiles) cannot be approximated by normal one. Nonparametric indices are used. Separation of soil groups using substantial properties does not guarantee data fetches with normal distribution for all morphometric properties. Soil types and subtypes according to Russian soil classification system have different complex of statistical distributions of soil horizon’s depth. Many differences are related to changes of carbonate profile, development of secondary solonetzicity, crust formation, local surface washout and accumulation of upper part of arable horizon.

Soil respiration, which is one of the main fluxes in the global carbon cycle, is characterized by high temporal and spatial variability. Based on the year-round continuous 21-year monitoring of the respiration of soddy weakly-podzolic soil in the forest and meadow coenoses of the southern taiga zone, an assessment of the temporal variability of CO₂ fluxes from soils was made at different time levels: monthly, seasonal, and annual. The values of total respiration of soddy weakly-podzolic soil varied most significantly at the monthly averaging level (coefficient of variation, CV=25–56%), while the variability of the annual respiration of soils was 20–22%. At the seasonal averaging level, the highest variability (CV=39–44%) was noted for winter CO₂ fluxes from soils, whereas the variability of total soil respiration in the other calendar seasons was close and amounted to 26–29%. The effect of the type of cenosis on the total CO₂ fluxes from the soddy weakly-podzolic soil was statistically significant both at the annual averaging level and in all calendar seasons of the year, except for winter. The most stable indicator characterizing the seasonal distribution of CO₂ fluxes within a year is the contribution of the warm period (May–October) to the total annual CO₂ flux from soils, which averages 73–77%. Its variability over 21 years of observation in both coenoses was 8%. It can be recommended to use this indicator to obtain estimates of annual CO₂ fluxes from soils based on field measurements carried out only within the growing season. The numerical experiments performed have shown that continuous measurements of CO₂ emission from soils for five consecutive years reduces the variability of annual and seasonal CO₂ fluxes from soils by more than 2 times compared to a one- or two-year measurement period. This makes it possible to recommend a five-year observation period as the optimal required for obtaining adequate values of annual and seasonal CO₂ fluxes from the soils of the southern taiga zone. 

The current state of the problem of soil mapping is considered. It is shown that there has been a replacement of traditional soil mapping methods by methods based on geoinformation digital and remote sensing technologies. The main advantages and disadvantages of the currently used soil mapping methods are outlined, and the necessity of taking into account the level of generalization of the information used in the process of soil mapping is demonstrated. We demonstrated the errors arising in soil maps when digital spatial data with different levels of information generalization is used. The most promising directions in the development of soil mapping methods are identified. It is shown that the primary attention should be paid to the development of digital soil mapping methods based on remote sensing data, which contain the most accurate information on the spatial variation of the surface soil horizon properties. The use of methods of spatial interpolation of point data is less accurate than the use of remotely sensed data. But the latter allows us to confidently detect only certain soil properties and not all of those necessary to create soil maps in the traditional form. Mapping individual soil properties is a more promising approach. Maps of individual soil properties are more convenient and accurate for evaluating soil and land resources. In the future, they can be used as a basis both for the re-creation of soil units in terms of accepted soil classification and for the creation of soil maps in traditional form (with the reflection of classification units of soils on them). But for a complete transition to the mapping of soil properties, it is necessary to deepen research in studying the spectral reflectance of the soil surface and its relationship with the properties of the underlying soil horizons.

The article is a review of the scientific problems that the Honored Professor of the Lomonosov Moscow state university Evgeny Anatolyevich Dmitriev. The main area of his scientific interests is the genesis of soil and land cover data. Numerous works carried out under his supervision convincingly demonstrate the influence of sampling methods on the results of determining certain soil properties. As a consequence, this influence also extends to the final conclusions, which can be highly distorted if the method of obtaining them is not taken into account. In an attempt to solve the question “What classifies soil classification?”, he develops the concept of “single soil”, which can be the object of soil classifications, not being directly a soil body, but acting as a kind of standard element of sampling. Theoretical understanding of the influence of heterogeneity of soils and soil cover at all hierarchical levels on the features of its “life” is the subject of the second part of the scientific legacy of E.A. Dmitriev. He puts forward the concept of soil bodies of different dimensions, shows the influence of the dimensional characteristics of these bodies on soil regimes and, in particular, on the water regime, and discusses the need to study soil regimes at different hierarchical levels. To fix the heterogeneity of the soil and soil cover, he developed special devices, with the help of which studies were carried out on soddy-podzolic, gray forest, chestnut, and other soils.

The features of anthropogenic transformation of natural chestnut soils and genesis of urban soils and conditions of the dry-steppe natural zone on the territory of Volgograd were studied in detail. The study was carried out by comparing the morphological characteristics of natural soils and their anthropogenic-modified counterparts. A morphological description was carried out for each of the 16 transects. The morphological characteristics of urban soils and chestnut soils of the city outskirts were compared. Under the influence of urban pedogenesis, natural light humus horizons AJ disappear, and the average thickness of diagnostic xerometamorphic horizons BMK decreases. The upper boundary of accumulative-carbonate horizon BCA lowered relative to the surface by an average of 32 cm compared to natural chestnut soils. Under the influence of urban-techno-pedogenesis there appeared inclusions represented by debris of building materials and garbage, accumulated in the process of human settlements functioning, the structure, density, nature of boiling from HCl 10% have changed. Modern surface horizons often boil off HCl 10%. In the landscaped recreational areas of the city, carbonate leaching has occurred due to irrigation of the area. The variants of morphological transformation of chestnut soils formed on the territory of Volgograd as a result of urban pedogenesis have been revealed. The first variant - soils of initial stages of technotransformation, with changes at the level of the upper horizons. The second option — soils with thick urban horizons, overlapping the preserved diagnostic horizons. The third option — burial of natural rocks by man-made soils of varying thickness with almost complete destruction (removal) of natural soil horizons. The fourth option — soils with thick humus horizons formed at the expense of intensive infusion of organic matter in underpourings of compost. It is noted that most of the soils of the city have profiles, completely formed on man-made sediments, and do not contain natural soil horizons in the upper 1,5 m thickness. According to the Field Identification of Soils of Russia, the studied soils of the first variant of transformation are defined as urban-stratified. The soils of the other options of transformation can be attributed to man-made surface formations. The content of organic carbon in the urban, technogenic, and replanted horizons averages 1,1, 0,25, and 1,6%, respectively. Chemical analysis of urbic, reclamation, and technogenic horizons revealed a low content of readily soluble salts — 0,14% and carbonates — 0,9%. Density in UR and RAT horizons is on average 1,4─1,43 g/cm³, in TCH horizons — 1,55 g/cm³. Buried horizons average density is 1,43 g/cm³ in AJ, 1,49 g/cm³ in BMK, 1,62 g/cm³ in B, and 1,54 g/cm³ in BCA, which is higher than average density for native chestnut soils. Also for the buried horizons is characterized by leaching from salts (mid. 0,2%) lower values of calcium carbonate content than in the background, alkalinization of the environment, as well as a decrease in organic carbon by an average of 0,35% in the AJ, BMK, and B horizons, and by 0,28% in BCA. The average CaCO3 content in the upper humus and median horizons is 1,4% and in the carbonate horizon 4,3%. The obtained results allow us to study in more detail the peculiarities of the genesis of urban soils and the anthropogenic transformation of natural chestnut soils in urban conditions of the dry-steppe natural zone.

Water-soluble organic substances (WSOM) of sod and humus horizons of Mollic Gleysol artificially saturated to full moisture capacity were isolated by sequential centrifugation from pores with a diameter of more than and less than 30 microns. The total concentration of carbon and phenolic compounds, the absorption and fluorescence spectra of the solutions do not differ significantly, but a strong variation in the parameters (the ratio of maximum and minimum values is 415 times) indicates the heterogeneity of the composition of the extracted substances. The concentration of simple phenolic acids in solutions of large pores of the humus horizon is 48 times higher than in smaller ones, salicylic, benzoic and cinnamic acids predominate (75% of the total amount). In small pores, p-hydroxybenzoic and benzoic acids predominate (67% of the total amount). Dissolved organic matter (DOM) of soil solution of the Podzolic soil (ELBTg horizon, moisture 22%), were obtained by tension lysimeters from pores with a diameter of more and less than 14.7 microns. DOM in solutions from large pores contain more C, N, phenolic compounds and, according to the absorption spectra, have a large molecular weight and a degree of aromaticity. Organic substances from small pores are more hydrophobic and are characterized by a greater C:N ratio; these features potentially promote DOM resistance to decomposition. Predominant localization of phenolic substances in large pores is favourable for the conservation in soil since transport with water flows assist their chemical stabilization in the lower horizons as organo-mineral compounds.