Vera Petrovna Samsonova

Spatial variability of agrochemical properties of arable soils (case study: Trubchevsk district of the Bryansk region)

Moscow University Bulletin. Series 17. Soil science. 2019. N 2. p.28-35

Vera P. Samsonova Marina I. Kondrashkina Dmitry G. Krotov

1317

The degree of spatial variation of agrochemically important properties of plowing horizon (pH KCl, hydrolytic acidity, absorption capacity, the degree of saturation of bases, humus content, mobile phosphorus and exchange potassium) is estimated. It is shown that the partition of the set into subsets corresponding to classification units significantly reduces the degree of variation of humus and physico-chemical properties, practically without changing the variability of pH, the content of mobile phosphorus and exchange potassium. Discriminant analysis shows that the arable horizons of sod-medium podzolic, gray forest and dark gray forest soils are satisfactorily classified for a given set of properties. Poorly classified bog-podzolic and gray forest gleyed soils. Light gray forest soils occupy an intermediate position, gravitating toward gray forest soils.

Keywords: spatial variability; agrochemical properties; discriminant analysis

Scientifi c heritage of the honorary professor E.A. Dmitriev

Moscow University Bulletin. Series 17. Soil science. 2022. N 2. p.3-12

Vera P. Samsonova

1541

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.

Keywords: spatial heterogeneity of soils and soil cover; statistical methods; soil classification

Spatial variability of the granulometric composition within arable fi eld on soddy-podzolic soil

Moscow University Bulletin. Series 17. Soil science. p.61-67

Vera P. Samsonova Yulia. L. Meshalkina Marina I. Kondrashkina Svetlana Ev. Dyadkina Anastasia V. Zotkina

1204

The spatial variability of the content of granulometric fraction d > 0,25 mm in the arable layer of soddy-podzolic cultivated soil on an area of 18 hectares was studied. The soil formed in the loess-like loam, underlain by moraine deposits. Samples were taken from the upper (0–10 cm) and lower parts of the arable layer (10–20 cm) following a random-stratified sampling scheme. The total number of samples was 350 cores. The average fraction content was about 22%, the coefficient of variation was 39–41%, the distributions were approximated by a logarithmically normal distribution. The Spearman correlation coefficient between values at different depths equaled to 0,87. The spatial distribution cartograms were constructed by the ordinary kriging method using a spherical variogram model. It is shown that preliminary censoring of high sample values (quantile 0,95) gives better results when constructing a cartogram than removing a linear spatial trend and logarithm of the original data. Spatial structures with reduced and increased values were found on the site, the average linear sizes of which was about 100 m. Presumably, they were associated with the heterogeneity of soil-forming material.

Keywords: censorship; ordinary kriging; cartogram; loess-like loams; Moscow region; coarse and medium sand; gravel

The number of repetitions during of the soil organic carbon content monitoring in the forest revisited

Moscow University Bulletin. Series 17. Soil science. 2024. N 1. p.16-23

Vera P. Samsonova Yulia. L. Meshalkina Marina I. Kondrashkina Svetlana Ev. Dyadkina

1249

Using the example of data from the article by E.A. Dmitriev et al., the estimation of the required number of soil samples to assess the SOC content in the forest biogeocenosis during monitoring studies is considered. Primary data on SOC content were obtained in the spruce forest at 166 points in layers 0–10, 10–20, and 20–30 cm after removal of the litter. The sampling was carried out at the nodes of a regular grid of equilateral triangles with 1 m side within a regular hexagon with a side of 7 m. The SOC content was determined by the Tyurin method. The original article presents statistics for three zones — near-stem, under-crown and inter-crown space. Spatial variation in all zones and at all depths is high, the coefficients of variation are about 50%. It is shown that the number of replicates required for estimating the average SOC content at a 95% confidence level in the 0–10 cm layer is hundreds of samples and decreases to tens of samples in the 20–30 cm layer. Since the number of repetitions for testing hypotheses about the equality of means depends not only on the confidence level, but also on the power of the criterion used, the required number of repetitions increases several times. Sampling with samples taken from the entire vertical layer of 0–30 cm and forming mixed samples from them reduces the number of required repetitions, however, careful observance of sample preparation, including primary mixing of samples, is required.

Keywords: carbon stocks; coefficient of variation; estimation of the mean value; contrast of means; significance level; power analyses; sample size; mixed samples

Mapping of cropland humus content of the Bryansk region using machine learning methods

Moscow University Bulletin. Series 17. Soil science. 2024. N 4. p.130-140

Lidiya Yuryevna Konoplina Yulia. L. Meshalkina Vera P. Samsonova Oleg M.Golozubov

1004

The FAO methodology within the Global Soil Nutrient and Nutrient Budget Maps (GSNmap) project was tested for the first time for mapping humus content with a spatial resolution of 250 meters per pixel in soils of the Russian Federation at the regional scale, using the Bryansk Region as an example. The map was created in the R soft ware environment using data from Agrochemical Service and remote sensing, global databases and soil maps. The centroids of the sites from which the composite samples were taken by Agrochemical Service were selected as sampling points. The set of predictors available under the FAO project was expanded by additional data, including soil maps and maps of soil-forming rocks. The importance of the predictors was assessed using the Boruta algorithm, which is usually used as an initial stage for a random forest. The model was created using the caret package with the quantile regression forest method. The modeling efficiency coefficient (MEC) was 55%, the coefficient of determination (R2) was 0.57. The map reflects current information that can be used to monitor the dynamics of organic matter content in the soil and assess the state of the arable soils in the Bryansk region.

Keywords: soil organic matter; digital soil mapping; random forest; cross-validation

Analysis of intra-seasonal dynamics of organic carbon content in arable sod-podzolic soil

Moscow University Bulletin. Series 17. Soil science. 2025. N 3. p.22-29

Vera P. Samsonova Tatiana V. Lokalina Marina I. Kondrashkina Svetlana Ev. Dyadkina

567

The ongoing work on forecasting changes in soil carbon reserves using various mathematical models requires primary data for different points in time. The paper examines archival results of observations of intra-seasonal carbon dynamics obtained in 1983 on arable sod-podzolic soils in Educational and Experimental Soil and Ecological Center of Lomonosov Moscow State University "Chashnikovo". Measurements were carried out from June to September on 30×30 m plots located in three crop rotation fields. Samples were taken from layers 0‒10 and 10‒20 of the arable horizon. The number of measurements in each period on each field was 25. After preliminary rejection of the results that did not meet the hypothesis of homogeneity of the soil horizon, the data were processed by ANOVA. It is shown that in the arable horizon (0–20 cm layer) the range of intra-seasonal variability of carbon content can be about 0.10%. Minimum values of carbon content were observed in August-September.

Keywords: ANOVA; data culling; EE SEC "Chashnikovo"

An assessment of the most important carbon pools in the mixed forests of the Moscow region

Moscow University Bulletin. Series 17. Soil science. 2025. N 3. p.30-41

Alexey S. Sorokin Valeria M. Telesnina M. A. Podvezennaya Yulia. L. Meshalkina Olga Iv. Manakova Vera P. Samsonova Marina I. Kondrashkina Svetlana Ev. Dyadkina Mikhail R. Chekin Igor A. Ilyichev Svetlana. A. Kulachkova Olga I. Filippova

743

The carbon reserves in main components of Moscow region coniferous-broadleaf forest were studied: various fractions of the tree stand, dead wood, mortmass, litter, living ground cover and mineral profile of the soil. To assess the potential intensity of organic matter decomposition, a number of indicators of the functioning of the microbial biomass were determined. An assessment is given of the carbon reserves and their shares in the ecosystem components that differ in the rate of renewal and potential capacity for carbon sequestration, as well as the degree of their spatial variation. The total carbon pool of the studied forest ecosystem is 18.7+0.8 kg·m–2, with almost 90% of the total stock concentrated in the perennial parts of the tree stand, dead wood, mortmass and mineral profile of the soil. These most stable pools are characterized by the least spatial variation within the biogeocenosis. The carbon reserves of the assimilating part of the grass layer and tree leaves are only 0.02 and 0.08 kg·m–2, respectively. The carbon reserves of litter are quite low - 0.21 ± 0.04 kg·m–2, which does not exceed 2% of the total carbon reserves of the ecosystem. The data obtained indicate that even secondary subclimax forest ecosystems are a significant absorber of atmospheric carbon, mainly due to the mass of the tree stand and soil organic matter.

Keywords: secondary birch-spruce forest; soil organic matter; biological cycle; EE SEC "Chashnikovo"; carbon reserve; carbon sink

Quantitative comparative analysis of cropland masks of the Bryansk region

Moscow University Bulletin. Series 17. Soil science. 2025. N 4. p.139-146

Lidiya Yuryevna Konoplina Yulia. L. Meshalkina Vera P. Samsonova Oleg M.Golozubov

591

A comparative quantitative analysis of croplands masks of the Bryansk region was conducted by an expert method using the archive of remote sensing data from Google Earth. The first mask, with a spatial resolution of 250 m per pixel, was exported as part of the FAO GSNmap project. This mask is a product of the Land Cover global map provided by the Copernicus Global Land Service and is based on PROBA-V satellite images. The second mask was obtained from the Land Use/Land Cover (LULC) global map which is derived from Sentinel-2 satellite data. The mask was exported at a spatial resolution of 250 m per pixel. The overall accuracy of the Agrochemical Service, FAO, and LULC masks was calculated based on the visual interpretation of 900 randomly selected land plots in the Bryansk region. The accuracy values were 88.11% for the FAO and 88.00% for the LULC mask, and the kappa indices were 0.68 for FAO, and 0.67 for LULC mask. A comparative analysis of the FAO and LULC masks revealed a similarity of 81% between them. The conducted research indicates a high level of reliability of the cropland masks of the Bryansk region, based on satellite data from PROBA-V and Sentinel-2.

Keywords: DSM; remote sensing; satellite monitoring; LULC; Sentinel-2; PROBA-V

Introduction

Moscow University Bulletin. Series 17. Soil science. 2026. N 2. p.5-6

Vera P. Samsonova Yulia. L. Meshalkina

72

Uncertainties in digital soil mapping and possibilities of overcoming them

Moscow University Bulletin. Series 17. Soil science. 2026. N 2. p.7-16

I. Yu. Savin Vera P. Samsonova Daria Al. Zhulidova

98

Digital soil mapping (DSM) incorporates the most advanced approaches and methods in the computer analysis and modeling of spatial soil data. Currently, over 90% of all publications in the field of soil mapping are related to DSM. An analysis of scientometric databases and publications shows that the number of publications is growing annually, yet the declared quality of the resulting soil maps remains virtually unchanged. This is due to a number of factors, and the purpose of this article is to identify them through a review of scientific publications. The conducted research has shown that maps created using DSM approaches vary in quality. The accuracy of the models used to create digital soil maps, as declared by the authors, typically ranges from 30–40% to 70–80%. Sixteen potential sources of error in digital soil maps were identified, grouped into errors in the initial data on soil properties, initial data on predictors, errors in model selection, and errors in soils as a modeling object. Some sources of error can be eliminated now or in the near future, but there are errors whose elimination seems impossible at the current stage of scientific and technological development. The greatest potential for significant improvement in the quality of digital soil maps of surface soil horizon properties is present, while the least promising is for maps of soil classification names. The presence of errors in soil maps created using digital soil mapping methods should be disclosed during the creation of any soil map, including masking out areas of the map with the greatest errors.

Keywords: soil map; soil map errors; spatial modeling

Contribution of spatial components to soil bulk density variation in the birch-spruce forest of The Educational and Experimental Soil and Ecological Center of Lomonosov Moscow State University “Chashnikovo”

Moscow University Bulletin. Series 17. Soil science. 2026. N 2. p.69-79

Olga Iv. Manakova Vera P. Samsonova Yulia. L. Meshalkina

83

Information on natural variation in the soil bulk density values is an essential component in analyzing the uncertainty of organic matter reserves in biogeocenoses. The aim of this study was to assess the bulk density variation in a secondary birch-spruce forest in the Moscow region on sod-podzolic soils. Five test sites measuring 50×50 m were established on an area of approximately 2 ha. At each test site, a section and two semi-pits were established, in which soil density was determined at 10 cm vertical intervals using Kachinsky cutting rings with a volume of 100 cm3 in double replicates. Nested ANOVA was used to analyze the data, allowing for quantitative analysis of density variation at different distances (between sites and variation within sites between sections) and depths. The results showed that for the humus horizons themselves at a depth of 0-10 cm, the average density was 0.83 gcm‒3.It then increased with depth for the AE transitional horizons. The eluvial horizons were characterized by a density of about 1.50 gcm‒3 and occurred at a depth of 30‒40 cm. The density of the lower part of the profile varied from 1.65 to 1.85 gcm‒3. For the coefficient of variation, as for the standard deviation, a decrease in variation with depth is observed. The upper part of the profile is characterized by values of the coefficient of variation from 10 to 14%, and from a depth of 40 cm, the coefficient does not exceed 5%. The greatest contribution to density variation, 90%, at a depth from 0 to 30 cm is made by vertical soil heterogeneity. For individual 10-centimeter layers down to a depth of 30 cm, more than half of the dispersion is due to heterogeneity between pits at a distance of 10‒20 meters. The results of the work can be used to calculate the uncertainty of organic carbon stocks in the forest biogeocenoses of the southern taiga.

Keywords: uncertainty in soil bulk density estimation; Nested ANOVA; heterogeneity of soil properties

Uncertainty in the evaluation of total contamination of soil with heavy metals

Moscow University Bulletin. Series 17. Soil science. 2026. N 2. p.114-121

Vera P. Samsonova Marina I. Kondrashkina

52

Spatial variability in metal content in soils can lead to an unreasonably overestimated or underestimated level of contamination in an area, as determined by the total contamination coefficient ZС. Calculating this indicator based on sample experimental data yields only one value. For more reliable estimates, it is necessary to understand the possible range of this indicator, which describes the spectrum of reliability of contamination knowledge, ranging from low to high probability. Modeling the statistical distributions of heavy metal content under the assumption of logarithmic normality of their contents in both contaminated and background areas allows us to estimate the probability of ZС values falling into specific pollution categories. When classifying an area into a given pollution level, it is proposed to focus on the probability of obtaining individual high ZС values, even if the value itself is in a safe zone.

Keywords: spatial variability; total pollution index ZС; pollution modeling; logarithmic normality of HM content