Variability Of Soil Properties Research Articles

Examining intermediate soil properties variability through spatial interpolation methods in GIS

This study compares Kriging and Inverse Distance Weighting (IDW) spatial interpolation methods for estimating intermediate soil properties at a construction site in Astana, Kazakhstan. Using data from eight boreholes, seven engineering geological elements (EGE) were identified and analyzed at 6.5 m and 11.5 m depths. Kriging produced deformation modulus values ranging from -0.29 to 18.99 MPa at 6.5 m and -0.51 to 23.94 MPa at 11.5 m, capturing more spatial variability compared to IDW, which provided ranges of 3.3 to 18.99 MPa and 2.6 to 23.99 MPa, respectively. Kriging’s ability to account for spatial correlations resulted in more accurate predictions, particularly in areas with complex subsurface variability. Meanwhile, IDW offered reliable localized results, effective in more uniform geological conditions. The findings demonstrate that both methods are valuable for geotechnical applications, with the choice depending on data density and site variability.

Consideration of Different Soil Properties and Roughness in Shear Characteristics of Concrete–Soil Interface

To investigate the impact of diverse soil characteristics and surface irregularities on interfacial shear strength attributes, a large-scale straight shear apparatus and particle flow software were employed to conduct interfacial shear experiments with varying soil properties and surface irregularities. The results demonstrated that, under an identical R and normal stress conditions, the clay and silty clay shear stress–displacement curves exhibited strain softening, while the silt curve exhibited strain hardening. An increase in R can markedly enhance the peak shear strength at the interface, although a critical value exists beyond which this effect is no longer observed. The Rc is primarily contingent upon the soil properties. Numerical simulations demonstrate that the internal shear displacement and deformation resulting from the diverse soil properties are distinct. Clay particles are constituted of varying-sized particle aggregates that collectively resist shear. Silt particles resist shear through interfacial friction generated by shear. The practicality of Duncan and Clough’s constitutive model for interfacial shear with roughness influence is verified, and the constitutive model under strain hardening is modified.

Interpreting the spatial distribution of soil properties with a physically-based distributed hydrological model

Digital soil maps are commonly data-driven as the development of physically-based models for soil mapping is difficult due to the complexity of soils. However, physically-based hydrologic models have been successful in simulating water dynamics. Since water movement is a major driver of pedogenesis, the physical rules that govern water movement might help explain and predict the spatial variation of soil properties. Here, we demonstrate the novel use of a physically-based, distributed hydrologic model to inform the spatial distribution of soil properties. The Distributed Hydrology Soil Vegetation Model (DHSVM) was utilized to simulate soil moisture content (SM) and water table depth (WTD) in two hillslope catchments under pasture and forest management wherein hydrologic model outputs were then compared with soil properties measured in situ. SM sensors and wells were installed in both catchments to validate simulations of soil water movement via Nash-Sutcliffe Efficiency (E). In-situ observations were made at 87 sites within both catchments to study the connection between simulated water movement (SM and WTD) and observed soil properties, namely the depth and thickness of the argillic (Bt), fragic (Btx), and C horizons, and the depth of redoximorphic features. The simulated time series of SM and WTD were also clustered per season using Dynamic Time Warping (DTW), which identified similarity among time series at varying timescales. Model validation suggested that simulations of surficial SM (0–20 cm) were reasonable (E = 0.45), however, simulated subsurface SM (45–60 cm) and WTD were not sufficiently accurate. The thickness of Btx horizons were spatially grouped into different populations by SM clusters from every season except spring. For the other properties, only SM dynamics of specific seasons grouped into significantly different populations, suggesting that the explanatory power of simulated water movement varies seasonally and was greater during winter. Here, we show clusters of simulated SM separated soil properties into statistically different populations, showing that hydrologic models could inform areas that followed different water dynamics related to pedogenic trajectories and related biogeochemical processes not necessarily simulated by the model. As such, physically-based modeling of water dynamics can, therefore, inform and advance digital soil mapping by linking water movement patterns stemming from hydrologic model outputs to spatial patterns of soil properties and pedogenesis.

Intercropping in Coconut Plantations Regulate Soil Characteristics by Microbial Communities

Intercropping is a commonly employed agricultural technique that offers numerous advantages, such as increasing land productivity, enhancing soil health, and controlling soil-borne pathogens. In this study, Artemisia argyi, Dioscorea esculenta, and Arachis pintoi were intercropped with coconuts and compared with naturally growing weeds (Bidens pilosa), respectively. The regulatory mechanism of intercropping was examined by analyzing the variability in soil properties and microbial community structure across different intercropping modes and soil depths (0–20 cm, 20–40 cm, and 40–60 cm). The results indicate that intercropping can increase the diversity of soil bacteria and fungi. Moreover, as soil depth increases, the changes in microbial communities weaken. Intercropping reduced soil SOM and increased pH, which is directly related to the changes in the abundance of Acidobacteria in the soil. In various intercropping systems, the disparities resulting from intercropping with A. pintoi are particularly pronounced. Specifically, intercropping with A. pintoi leads to an increase in soil potassium and phosphorus levels, as well as an enhancement in the abundance of Bacillus sp., which plays a crucial role in the suppression of plant pathogenic fungi within the soil ecosystem. The results of the correlation analysis and structural equation modeling (SEM) suggest that the impacts of three intercropping systems on microbial composition and soil indicators exhibit considerable variation. However, a common critical factor influencing these effects is the soil phosphorus content. Furthermore, our findings indicate that intercropping resulted in lower soil nitrogen levels, exacerbating nitrogen deficiency and masking its impact on the microbial community composition.

Data Mining Virtual Contaminated Sites to Develop an Educational Learning Tool supported by a k-NN Machine Learning Predictive Algorithm for use in Environmental Engineering Education

Recent work by Mumford et al. used high-resolution numerical simulations of contaminated sites to evaluate the state of practice for contaminated site investigation1. These simulations were originally developed in collaboration with academic and industry partners, including the U.S. Department of Defense's Environmental Security Technology Certification Program (ESTCP), as a training tool for environmental monitoring and performance optimization. This project focuses on the development of an algorithm to determine available borehole information in those simulations based on user-input, to help leverage this work to create an educational tool. The algorithm begins by validating user-specified coordinates to ensure they fall within an acceptable range. Leveraging principles from linear algebra and a grid-based mapping system, it identifies the nearest existing borehole on a predefined coordinate grid. To optimize efficiency, the algorithm utilizes a 2-D array to store and retrieve coordinate data. It calculates distances from the input coordinates to all available borehole locations on the grid, to identify the shortest distance and select the closest borehole, enabling students to map contamination within virtual sites. In addition to boreholes, the application incorporates data for Membrane Interface Probes (MIPs), monitoring wells, groundwater samples, and soil samples that are used to investigate contaminated sites, providing a comprehensive tool for training environmental professionals. The k-nearest neighbors (k-NN) algorithm predicts Membrane Interface Probe (MIP) Photoionization Detector (ECD) readings at future locations, which indicate chlorinated contaminant levels. Two models were evaluated: one using spatial data and ECD values, and another incorporating electrical conductivity (EC) and hydraulic conductivity (K), which are also measured by MIP. By making use of additional parameters, variations in soil properties were better represented, leading to more accurate predictions. Through iterative testing and refinement, the tool’s accuracy and user-interface have been enhanced, ensuring robust reliability for classroom applications. These tools are slated for integration into 4th-year subsurface contamination courses at Queen's University, Carleton, and the University of Iowa. By automating borehole selection, instructors can interact more with students and dedicate less time to data processing tasks. The k-NN application will enable the use of machine learning for site assessment to optimize MIP instrument placement to reduce bias. Assistance from Cole Van De Ven (Carleton University) and Jessica Meyer (University of Iowa) in collecting virtual contaminated site data is gratefully acknowledged.

Soil Physical and Chemical Properties under Shea Tree (Vitellaria paradoxa) at Different Stages of Growth

Shea tree (Vitellaria paradoxa), is one of the dominant agro-forestry species in Otuke district of Northern Uganda. Due to its economic importance and, in line with the numerous threats the tree is faced with, there is an urgent need for measures to conserve this species, for example, through incorporating annual food crops in the Shea tree parkland. This, however, requires a better understanding of tree-soil-food crop interactions. A number of studies of this aspect either considered only the mature Shea tree gardens or did not provide a clear distinction between the physiological states of the Shea tree. This was the motivation for this study where we compare variation in soil properties under mature and young Shea tree gardens with sites not having trees in Okwang sub-county, Otuke district. Five soil samples (up to 15 cm deep for top soil and 15-30 cm for sub-soil) were obtained per treatment using a soil auger. Our results show that in the top soil, only percent sand varied among the treatments, while, in the sub-soil, only percentage nitrogen and average phosphorus varied among the treatments. We also found that percentage top soil organic matter and percentage of sub-soil sand had negative strong correlations with maize and soybean yields, while percentage sub-soil clay had a strong positive correlation with maize and soybean yield. We conclude that variations in soil physical and chemical properties under Mature and Young Shea gardens only occur for those properties that have a direct link to tree residues

Variability of soil properties and their implications for agricultural management in the central plain of Manipur, India

Variability of soil properties and their implications for agricultural management in the central plain of Manipur, India

Optimized irrigation and fertilization can mitigate negative CO2 impacts on seed yield and vigor of hybrid maize

Seed yield and vigor of hybrid maize determine the planting, yield, and quality of maize, and consequently affect food, nutrition, and livelihood security; however, the response of seed yield and vigor to climate change is still unclear. We established an optimization-simulation framework consisting of a water‑nitrogen crop production function, a seed vigor and a gridded process-based model to optimize irrigation and nitrogen fertilization management, and used it to evaluate seed yield and vigor in major seed production locations of China, the USA, and Mexico. This framework could reflect the influence of water and nitrogen inputs at different stages on seed yield and vigor considering the spatio-temporal variability of climate and soil properties. Projected seed yield and vigor decreased by 5.8–9.0 % without adaptation by the 2050s, due to the 1.3–5.8 % decrease in seed number and seed protein concentration. Seed yield was positively correlated with CO2 and negatively correlated with temperature, while seed vigor depended on the response of components of seed vigor to climatic factors. Under optimized management, the direct positive effects of temperature on seed protein concentration and CO2 on seed number were strengthened, and the direct negative effects of temperature on seed number and CO2 on seed protein concentration were weakened, which mitigated the reductions in both seed yield and vigor. Elevated CO2 was projected to exacerbate the 2.6 % seed vigor reduction and mitigate the 2.9 % seed yield loss without adaptation, while optimized management could increase seed yield by 4.1 % and mitigate the 2.2 % seed vigor reduction in the Hexi Corridor of China, and decrease the seed yield and vigor reduction by 2.4–5.8 % in the USA and Mexico. Optimized management can strengthen the positive and mitigate the negative effects of climate change on irrigated hybrid maize and inform high-yield and high-quality seed production globally.

Post-fire recovery of nematode communities along a slope gradient in a pine forest.

We investigated the enduring consequences of a wildfire on nematode diversity and abundance in a pine forest, employing a slope gradient approach. Our primary objective was to determine the extent of post-fire alterations in the nematode community 3years after the incident, to understand if the ecosystem has returned to its pre-fire state or has transitioned to a distinctive ecological environment. Three distinct burned pine forest sites at varying elevations were sampled to capture short-scale soil property variations due to slope gradients, while unburned forest sites served as controls. A consistent pattern emerged where the lowest altitude sites exhibited the highest nematode abundances, although still lower than unburned sites. Fire-induced changes were profound, shifting from fungivore dominance in unburned sites to bacterivore and herbivore dominance in burned sites. Alterations in soil properties post-fire, particularly reduced organic matter and nitrogen content, were closely associated with nematode community shifts. Water availability played a crucial role with lower moisture levels at higher elevations impacting nematode populations. Structural differences in the nematode community primarily resulted from fire disturbance rather than altitude. This study emphasizes the persistent and transformative impact of wildfire on nematode communities, highlighting the intricate interplay between ecological disturbances, soil properties, and nematode trophic dynamics.

Impacts of vertical variations in soil properties on H*(10) simulations for 137Cs deposition

Photon transport simulations based on the Monte Carlo method have played a crucial role in assessing and estimating the ambient dose equivalent rates H*(10), resulting from the deposition of 137Cs in soil following the nuclear power plant accident in Fukushima. However, a comprehensive examination of the effect of vertical variations in soil properties on the simulation outcomes has not yet been performed. Disregarding the vertical distribution of soil properties not only leads to potential inaccuracies in the shielding responses of soil layers but also in the determination of the radioactive source inventory, particularly when using the concentration data in Bq/kg. These oversights diminish the reliability of the simulation results. This study addresses several soil property factors that could potentially influence the simulation results, including variations in chemical composition induced by water content, bulk density profile, and estimated inventory profile, all evaluated through an examined simulation model. The results show that inappropriate assignment of the soil density profile can cause considerable errors in the H*(10) simulation outcomes. Furthermore, the sensitivity of H*(10) to variations in soil vertical density is analyzed, with the results indicating that H*(10) can be highly sensitive to changes in the bulk density of the top 0–5 cm soil layers. These results should facilitate the establishment of appropriate simulation strategies and support the reassessment of past simulation results.

A Ground-Penetrating Radar-Based Study of the Structure and Moisture Content of Complex Reconfigured Soils

To increase the detection accuracy of soil structure and moisture content in reconstituted soils under complex conditions, this study utilizes a 400 MHz ground-penetrating radar (GPR) to examine a study area consisting of loess, sandy loam, red clay, and mixed soil. The research involves analyzing the single-channel waveforms and two-dimensional images of GPR, preprocessing the data, obtaining envelope information via amplitude envelope detection, and performing a Hilbert transformation. This study employs a least squares fitting approach to the instantaneous phase envelope to ascertain the thickness of various soil layers. By utilizing the average envelope amplitude (AEA) method, a correlation between the radar’s early signal amplitude envelope and the soil’s shallow dielectric constant is established to invert the moisture content of the soil. The analysis integrates soil structure and moisture distribution data to investigate soil structure characteristics and moisture content performance under diverse soil properties and depths. The findings indicate that the envelope detection method effectively identifies stratification boundaries across different soil types; the AEA method is particularly efficacious in inverting the moisture content of reconstituted soils up to 3 m deep, with an average relative error ranging from 2.81% to 7.41%. Notably, moisture content variations in stratified reconstituted soils are more pronounced than those in mixed soil areas, displaying a marked stepwise increase with depth. The moisture content trends in the vertical direction of the same soil profile are generally consistent. This research offers a novel approach to studying reconstituted soils under complex conditions, confirming the viability of the envelope detection and AEA methods for intricate soil investigations and broadening the application spectrum of GPR in soil studies.

Rapid characterization of soil horizons for different soil series utilizing Vis-NIR spectral information

The visible-near infrared (Vis-NIR) reflectance technique is a powerful tool, particularly for obtaining faster information about soil texture, organic matter, and calcium carbonate content. However, there is limited research on the characterization of soil horizons using Vis-NIR data in profiles of different soil series. This study investigated the relationship between soil properties and spectral reflectance (Vis-NIR) in eight soil profiles with varying genetic properties from Harran Plain, Türkiye, focusing on variations within profiles (A, B, and C horizons) and across different soil series. A total of 36 soil samples were collected from the A, B, and C horizons, and spectral reflectance was measured along with calcium carbonate, organic matter, and particle size distribution. High variability was observed in calcium carbonate (11.58–52.50%) and organic matter content (0.60–3.71%), reflecting complex soil composition influenced by parent material and land management. Distinct reflectance patterns were observed within profiles, reflecting variations in soil composition. Ap horizons with higher organic matter content often exhibited lower reflectance (visible region). Clay content influenced NIR reflectance, with higher absorption in clay-rich profiles. The Kaynakli series (Fine-loamy, mixed, mesic Typic Calcixerepts) showed differentiation in reflectance between A and B horizons after 700 nm due to horizon formation and clay/carbonate accumulation. Increasing calcium carbonate content in Ck horizons led to higher reflectance compared to other layers. Confirmed that Vis-NIR reflectance could explain a significant portion of the variance in soil properties (A: 87.7%, B: 88.3%, and C: 90.6%). PCA results supported the notion that spectral signatures captured by Vis-NIR reflectance measurements are indicative of inherent differences between A, B, and C horizons. This study contributes to the growing body of knowledge on the application of Vis-NIR spectroscopy for soil assessment and monitoring. However, future research should focus on understanding spectral reflectance variations under diverse soil and environmental conditions.

Diffusion of innovative soil management practices for sustainable vegetable farming

Vegetable farmers in Sokoto state, Nigeria are disadvantaged by problem soils that are generally low in nutrient content, leading to below optimum output. As a result, this research was undertaken to disseminate innovative soil management practices through participatory on-farm trials using household waste compost, vermicompost, and biochar as treatments toward ensuring sustainable vegetable farming. The research covered a sequence of 3 main activities; including baseline survey through focus group discussion (FGD), pre and post project soil sample analyses (0-15cm and 15-30cm depths) and trials, and dissemination of findings via result demonstration, respectively. Findings from the baseline revealed that, the vegetable farmers were vulnerable and never had contact with an extension worker, living below $50/month and confronted by dwindling vegetable output due to acidity and low nutrient content of the soil. Amaranth, cabbage, lettuce, tomatoes, peppers, onions, and carrot were the mainly cultivated vegetables by the farmers. Soil management practices in the research sites were occasional application of inorganic fertilizers and traditional application of municipal waste, crop residue and refuse, which was due to inadequate knowledge on sustainable management practices of the soil. Application of organic amendments including household waste compost, vermicompost, and biochar caused tremendous variation in post-project soil properties (EC, K, Na, Ca, Mg, CEC, N, OC and P). Similarly, yield and benefit cost ratio of the trial crop (amaranth) significantly improved due to the amendments. Hence, application of organic soil amendments especially household waste and biochar would be worthwhile for sustainability of vegetable farming in Sokoto state, Nigeria.

A novel efficient RFEM for reliability analysis and design of multi-line dynamically installed anchor for floating offshore wind turbines

A novel multi-line dynamically installed anchor was previously proposed by the authors to allow for the mooring of multiple floating offshore wind turbine, resulting in a significant reduction in the total number and cost of anchors required for floating wind farms. Considering the spatial variability of soil properties and the uncertainty of environmental loads, the present study performs reliability analysis and design of the multi-line dynamically installed anchor. Firstly, a strategy to repeatedly use fundamental random variables is proposed and validated for reducing the number of random variables used in Karhunen-Loève expansion in the simulation of random field of soil properties when the ratio of the soil domain dimension to the scale of fluctuation is large. Then, the efficiency, accuracy, and robustness of the RFEM (random finite element method) combined with K-MCS (Kriging model and Monte Carlo simulation) based on the proposed strategy are validated through examples of random capacity of foundations. Next, the random capacities and probabilistic VHMT failure envelopes of the multi-line dynamically installed anchor in spatially variable soil are investigated. Finally, the reliability design of multi-line dynamically installed anchors is conducted and compared with that of multi-line pile anchors, in which both the spatial variability of soil and the uncertainty of loads are condidered. The results show that the costs for multi-line dynamically installed anchors are obviously less than those of multi-line pile anchors.

Exploring Spatial Variability and Yield-Determining Factors in Cotton Production: A Multivariate Analysis

ABSTRACT The yield of cotton crops is severely affected by the soil’s chemical characteristics. This research probes the influence of soil properties on cotton yield, with a focus on assessing within-field spatial variability for advanced site-specific management in cotton production. Geostatistical analysis and semivariograms were conducted to examine the spatial variability of soil chemical properties. While multivariate analysis was employed to identify key yield-determining factors. Principal Component Analysis (PCA) was employed to explore leading soil indicators, as opposed to using a pre-defined set of indicators, and to analyze the spatial variability of soil properties. The soil characteristics encompassed saturation, soil pH, electrical conductivity (EC), organic matter (OM), phosphorous (P), potassium (K), calcium carbonate (CC), and micronutrients such as zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), and boron (B). For this study, one thousand soil samples were meticulously collected from the Multan district, facilitated by Global Positioning System (GPS) devices. The PCA revealed that the first four PCs accounted for 57% of the total variation. The first PC, Cu, B, Mn, OM, and Fe emerged as the most influential variables, while the second PC exhibited a high correlation with CC, pH, and saturation. The third PC highlighted the dominant role of K and P in its construction, whereas the fourth PC was primarily shaped by Zn. The Principal Component Regression (PCR) analysis further revealed that EC, K, P, and Zn had positive impacts on cotton yield, while pH, Cu, Fe, Mn, and B had negative impacts.

Assessing Micronutrients in Soil with a New Chemical Extractant Using Isotopic Dilution Techniques: Linkages to Labile Fractions in Soil

ABSTRACT With the purpose of economizing the routine soil testing for micronutrients and avoiding the use of multiple soil extraction procedures, a laboratory investigation was attempted to evaluate a new chemical extractant for assessing the availability of common micronutrients (Fe, Cu, Mn, Zn, Mo, and B) in soils of widely varying properties (n = 32). The new extractant designated as OM-MES-VERA# contained 0.01 M oxalic acid, 0.02 M maleic acid, 0.02 M 2-(N-Morpholino) ethane sulfonic acid (MES), 0.0025 M ethylene diamine tetraacetic acid di-sodium salt, 0.02 M acetic acid, and 0.1% polyacrylamide (final pH adjusted to 6.0). OM-MES-VERA extracted significantly higher amounts of micronutrient cations and B from soils compared to the conventional diethylene triamine pentaacetic acid (DTPA, pH 7.3) extractable micronutrient cations and hot water soluble B, respectively, but lesser amount of Mo compared to Mehlich-3 universal extractant. Soil test values by both OM-MES-VERA- and conventional extractants were correlated with soil properties. The labile (E and L) values of micronutrient cations and Mo estimated by isotopic dilution method, ammonium bicarbonate-DTPA, pH 7.6 extractable soil B (as an estimate of E for B) and B concentration in maize (as an estimate of L for B) were successfully regressed on soil test values of micronutrients by OM-MES-VERA and conventional soil extractants except in the case of DTPA (pH 7.3) for E-value of Fe and L-value of Mn. The OM-MES-VERA extractant can be considered to assess the availability of common micronutrients in soils of diverse soil properties.

Effects of Spatial Variation in Relative Density on Seismic Behavior of Saturated Sandy Ground

Proper consideration of variations in soil properties and their effects is necessary to enhance the seismic safety of structures. In this study, the effect of spatial variations in the cyclic resistance ratio on seismic ground behavior was investigated. Initially, dynamic centrifuge model tests were conducted on sandy ground featuring a 20% mixture of weak zones with low relative density and on homogeneous sandy ground with no mixture of weak zones. Subsequently, an effective stress analysis was performed by modeling the distribution of weak zones in the centrifuge model tests. Finally, after confirming the validity of the parameter settings, several analytical models with different weak-zone distributions were generated and numerically analyzed using random field theory. The results indicate that a local mixing of approximately 20% weak zones has only a limited effect on overall ground behavior. However, differences were observed in the rate of increase and dissipation of the excess pore water pressure ratio and in the residual horizontal displacement.

Variation in wheat yield and soil properties at different landscape positions, nutrient sources, and rates in the tropical cereal-based cropping systems of Ethiopia

Variation in wheat yield and soil properties at different landscape positions, nutrient sources, and rates in the tropical cereal-based cropping systems of Ethiopia

Mechanisms of enhancing MgO for stabilization/solidification of Pb-contaminated red clay through CO2 sequestration

Pb-contaminated soil poses significant environmental and health risks as well as soil stability issues. Research on sandy soils highlights CO2-enhanced reactive MgO as a promising solution for improving the solidification of Pb-contaminated soils. However, carbonation effects can differ markedly between soil types owing to varying soil properties. In this study, we evaluated the effects of CO2-enhanced reactive MgO on the engineering and environmental characteristics of Pb-contaminated red clay and explored its mechanism of carbonation solidification. The results showed that CO2-enhanced reactive MgO increased the strength of Pb-contaminated red clay to over 3 MPa within 1 h, which was approximately 25 times the strength of untreated soil (0.2 MPa) and significantly higher than that of reactive MgO-treated, uncarbonated soil (0.8 MPa). The pH of the carbonated soil (9–10) facilitated Pb2+ immobilization, and the increase over the initial parameter elevated the electrical conductivity value. Moreover, CO2-enhanced reactive MgO reduced the Pb2+ leaching concentration to below 0.1 mg/L, even at high Pb concentrations (10,000 mg/kg). Pb2+ transformed into lead carbonates during the carbonation process, with the hydrated magnesium carbonates forming a dense internal structure. This solidification mechanism included chemical precipitation, physical adsorption, and encapsulation. Notably, the carbonation time should be controlled within 1 h to prevent soil expansion. Together, these findings support the potential of CO2-enhanced reactive MgO for efficient and low-carbon application in the solidification of Pb-contaminated red clay.

ТРАНСФОРМАЦИЯ ПЛОДОРОДИЯ ПОЧВ ЗАЛЕЖЕЙ ЛЕСОСТЕПНОЙ ЗОНЫ ПРИ РАЗЛИЧНОМ НАПРАВЛЕНИИ ИХ ИСПОЛЬЗОВАНИЯ

The purpose of research is to provide a comprehensive comparative assessment of the fertility of gray fallow soils in the forest-steppe zone of the Krasnoyarsk Region, overgrown with forest, used for hayma-king and re-developed into arable land. The studies were conducted in 2007–2020 in the Krasnoyarsk and Achinsk-Bogotol forest-steppe on gray soils of fallow lands no longer used for agricultural purposes. Stu-dies were carried out to assess the indicators of the potential and effective fertility of gray soils of fallow lands of the Krasnoyarsk and Achinsk-Bogotol forest-steppe with their various post-agrogenic use. It has been established that forests regenerated on fallow lands do not lead to degradation of soil fertility, especially in terms of the content of humus and agronomically valuable aggregates. The emerging forest litter and tree litter accelerate the accumulation of organic matter, a source of humus. There is weak spatial va¬riation in most indicators of effective and potential fertility in soils under regenerating forest compared to pure fallow lands. With the re-involvement of fallow land into arable land, nitrification somewhat increases, spatial variation in soil properties decreases, and the content of humus and absorbed bases decreases. The structural composition of the soils of all study objects is characterized as excellent (ACF 88–77 %) with an insignificant value of the coefficient of variation of fractions (4–7 %). When reclaiming fallow lands into arable land, the proportion of the blocky fraction is significantly reduced. The spatial variability of the structural composition of soils in fallow lands and hayfields is higher than on arable land, which is asso¬ciated with the “clumpiness” of the ground cover and root system of plants on uncultivated soils. In terms of fertility, post-agrogenic gray soils used for haymaking occupy an intermediate position between clean fallow lands and those overgrown with forest. The productivity of the phytomass of fallow lands, arable land and hayfields in the Krasnoyarsk and Achinsk-Bogotol forest-steppe is more closely correlated with the indicators of the potential fertility of post-agrogenic gray soils. In most cases, the values of the correlation coefficients are closer between phytomass reserves and indicators of effective fertility in the Achinsk-Bogotol forest-steppe, which is associated with more favorable hydrothermal conditions in this research area and optimal water-physical properties.