Mixed Soil Samples Research Articles

Estimation of maximum void ratio with effect of fines content for soil mixtures

Studies of binary packing mixtures provide beneficial insight into the effects of fines content on the void ratio of multi-sized granular materials. There are some mathematical models that predict the limit void ratios, however, the results obtained through these models have shown some discrepancies with the experimentally measured limit void ratios. To overcome this issue, the target of this study was to extend the mathematical model previously proposed by the authors for estimating minimum void ratios of soil mixtures to predict the maximum void ratios of soil mixtures. The extended model is verified by data from 37 soil mixtures with various soil samples. The predictions fitted well with the experimental results with various fines content for both coarse- and fine-dominant regions with the root mean square error equal to 0.043. Moreover, 44 tests were conducted on 22 different mixed graded soil samples from the Nakdong river soil in Busan to obtain the minimum and maximum void ratios. The predictions of the test results for the minimum and maximum void ratios via the model confirmed the applicability of the proposed model.

Experimental Study on Mechanical Properties of Recycled Aggregate Mixed Soil.

In the context of efforts aimed at reducing carbon emissions, the utilization of recycled aggregate soil mixes for soil stabilization has garnered considerable interest. This study examines the mechanical properties of mixed soil samples, varying by dosage of a soft soil curing agent C, recycled aggregate R content, and curing duration. Mechanical evaluations were conducted using unconfined compressive strength tests (UCS), field emission scanning electron microscopy (FESEM), and laser diffraction particle size meter tests (PSD). The results indicate that the strength of the mixed soil samples first increases and then decreases with higher dosages of recycled aggregate, reaching optimal strength at a 20% dosage. Similarly, an increase in curing agent dosage enhances the strength, peaking at 20%. The maximum strength of the mixed soils is achieved at 28 days under various proportions. The introduction of the curing agent leads to the formation of a flocculent structure, as observed in FESEM, which contributes to the enhanced strength of the soil mixes. Specimens prepared with a combination of 20% R and 20% C, maintained at a constant moisture content of 20%, and cured for 28 days exhibit a balance between economic, environmental, and engineering performance.

Properties of psammozems of the Kama terraces above the floodplain and assessment of their sustainability to pollution by Cu and Cd

Pine forests growing on psammozems, found on sandy Kama terraces above the floodplain within the territory of Perm, encompass roughly 2 thousand hectares. The study was conducted on psammozems under the influence of advancing pollution caused by heavy metals, highlighting the significance of soil’s buffering capacity in preserving the ecosystem’s stability. It is of great interest to investigate the morphogenetic properties of psammozems and evaluate the risks linked to the accumulation of Cu and Cd in these soils through the analysis of changes in soil enzyme activity (catalase, urease, and invertase) and the occurrence of phytotoxicity. The psammozems found in the Kama region originated from periglacial sandy alluvium, which was deposited during glacial melting in the Mesozoic era. The variety of humus psammozems includes typical, podzolized, illuvial-ferruginous, and pseudofibrous subtypes. These soils are highly acidic, have a very low absorption capacity, low base saturation, and reduced activity of soil enzymes. The contents of Cu, Cd, Zn, and Pb in psammozems are notably lower compared to the regional soil clarks; however, in the underdeveloped humus horizons, the concentrations of these metals are slightly higher than in soil-forming sands. The experiment was conducted to determine the ecotoxicological load, where mixed soil samples from a 0–20 cm layer of humus psammozems were treated with solutions containing copper acetate and cadmium acetate. The application of solutions was done individually, with Cu and Cd ranging from 2.5 to 250 mg/kg of soil. Upon introducing Cu and Cd into the soil at the rate of 2.5–10 mg/kg, a decrease in invertase activity, deterioration of the physiological and biochemical parameters of the test crop (Lepidium sativum L.), along with the inhibition of Cd catalase activity, were observed.

Effect of Biochar on NO3--N Transport in Loessial Soil and Its Simulation

The objective of this study was to explore the effects of different amounts of biochar on the migration process and characteristics of NO3--N in loessial soil. In this study, six groups of mixed soil samples with biochar and loessial soil mass ratios of 0% (T0), 1% (T1), 2% (T2), 3% (T3), 4% (T4), and 5% (T5) were used as research objects. NO3--N was used as the tracer. Through the indoor soil column solute transport simulation tests, the effects of different biochar application amounts on the NO3--N transport process in loessial soil were simulated and studied. The results showed that the breakthrough curve of NO3--N in loessial soil shifted to the right with the increasing of biochar application, and the peak value gradually decreased. The initial penetration time, complete penetration time, and total penetration time increased with the increasing of biochar application amount. The total penetration time of NO3- in the T1, T2, T3, T4, and T5 treatments was 1.26, 2.31, 2.72, 3.22, and 3.57 times that of T0, respectively. The R2 was > 0.997 and RMSE was < 2.083 of the two-zone model (TRM). Compared with the convection-dispersion equation (CDE), the TRM model had higher fitting accuracy and could better simulate the NO3--N migration process in loessial soil after the application of different contents of biochar. The analysis of the fitting parameters of the TRM model showed that the average pore velocity, hydrodynamic dispersion coefficient, and water content ratio in the movable zone gradually decreased with the increasing of biochar application, whereas the dispersion and mass exchange coefficient showed an increasing trend. The results showed that biochar application could effectively enhance the ability of loessial soil to fix NO3--N, reduce the leakage of NO3--N to groundwater, and play an important role in maintaining soil fertility and preventing groundwater pollution.

Screening of cellulose-degrading bacteria and optimization of cellulase production from Bacillus cereus A49 through response surface methodology

Cellulose-degrading microorganisms hold immense significance in utilizing cellulose resources efficiently. The screening of natural cellulase bacteria and the optimization of fermentation conditions are the hot spots of research. This study meticulously screened cellulose-degrading bacteria from mixed soil samples adopting a multi-step approach, encompassing preliminary culture medium screening, Congo red medium-based re-screening, and quantification of cellulase activity across various strains. Particularly, three robust cellulase-producing strains were identified: A24 (MT740356.1 Brevibacillus borstelensis), A49 (MT740358.1 Bacillus cereus), and A61 (MT740357.1 Paenibacillus sp.). For subsequent cultivation experiments, the growth curves of the three obtained isolates were monitored diligently. Additionally, optimal CMCase production conditions were determined, keeping CMCase activity as a key metric, through a series of single-factor experiments: agitation speed, cultivation temperature, unit medium concentration, and inoculum volume. Maximum CMCase production was observed at 150 rpm/37 °C, doubling the unit medium addition, and a 5 mL inoculation volume. Further optimization was conducted using the selected isolate A49 employing response surface methodology. The software model recommended a 2.21fold unit medium addition, 36.11 °C temperature, and 4.91 mL inoculant volume for optimal CMCase production. Consequently, three parallel experiments were conducted based on predicted conditions consistently yielding an average CMCase production activity of 15.63 U/mL, closely aligning with the predicted value of 16.41 U/mL. These findings validated the reliability of the model and demonstrated the effectiveness of optimized CMCase production conditions for isolate A49.

Investigation of Unsaturated Soil Hydraulic Properties for Subgrade Improvement using Marble Dust Waste

Introduction The distribution of suction, which has implications for seepage and shear strength, plays a crucial role in determining the stability of unsaturated soil. The Air Entry Value (AEV) and Residual Water Contents (RWC) change over time to create the Soil-Water Characteristic Curve (SWCC), which is very important for figuring out how the suction is distributed. During a flood occurrence, the subgrade becomes inundated with water, leading to adverse effects on the AEV and RWC of the subgrade. Consequently, the performance of the subgrade is diminished. This study focuses on the use of Marble Dust Waste (MDW) as an addition to the subgrade to improve the strength of the subgrade. Aims This study aims to investigate the variations in air AEV in relation to the optimal MDW in unsaturated soil found in Malaysia. Methods The study uses control samples and soil that has been mixed with different amounts of MDW: 5%, 10%, 15%, 20%, and 25%. The SWCC is generated using the pressure plate extractor device. Results The results indicate a significant increase in the AEV for the mixed soil sample when compared to the control sample. While the soil-MDW mixture containing 5% of this material has an AEV value of 23 kPa, the control sample's value is 10 kPa. Conclusion The findings of the study suggest that the utilization of MDW yields a beneficial influence on the AEV, hence potentially improving the performance of the subgrade. The researchers aim to evaluate the potentially dangerous waste and convert it into a substance that is appropriate for engineering applications. This study provides empirical evidence that aligns with the objectives outlined in Chapter 8 of the 12th Malaysia Plan for the period 2021–2025. The topic under discussion pertains to environmental sustainability, specifically focusing on enhancing the ability to withstand the adverse effects of climate change and disasters, as well as the Green Technology Master Plan Malaysia 2017–2030, with a specific emphasis on Chapter 6, which addresses the issue of waste management.

The discrepant metabolic pathways of PAHs by facultative anaerobic bacteria under aerobic and nitrate-reducing conditions

Studies regarding the facultative anaerobic biodegradation of polycyclic aromatic hydrocarbons (PAHs) were still in the initial stage. In this study, a facultative anaerobe which was identified as Bacillus Firmus and named as PheN7 was firstly isolated from the mixed petroleum-polluted soil samples using phenanthrene and nitrate as the solo carbon resource and electron acceptor under anaerobic condition. The degradation rates of PheN7 towards phenanthrene were detected as 33.17 μM/d, 13.81 μM/d and 7.11 μM/d at the initial phenanthrene concentration of 250.17 μM with oxygen, nitrate and sulfate as the electron acceptor, respectively. The metabolic pathways toward phenanthrene by PheN7 were deduced combining the metagenome analysis of PheN7 and intermediate metabolites of phenanthrene under aerobic and nitrate-reducing conditions. Dioxygenation and carboxylation were inferred as the initial activation reactions of phenanthrene degradation in these two pathways. This study highlighted the significance of facultative anaerobic bacteria in natural PAHs biodegradation, revealing the discrepant metabolic fates of PAHs by one solo bacteria under aerobic and anaerobic environments.

Mechanism of phenanthrene degradation by the halophilic Pelagerythrobacter sp. N7

PAHs has shown worldwide accumulation and causes a significant environmental problem especially in saline and hypersaline environments. Moderately halophilic bacteria could be useful for the bioremediation of PAH pollution in hypersaline environments. Pelagerythrobacter sp. N7 was isolated from the PAH-degrading consortium 5H, which was enriched from mixed saline soil samples collected in Shanxi Province, China. 16S rRNA in the genomic DNA revealed that strain N7 belonged to Pelagerythrobacter. Strain N7 exhibited a high tolerance to a wide range of salinities (1–10%) and was highly efficient under neutral to weak alkaline conditions (pH 6–9). The whole genome of strain N7 was sequenced and analyzed, revealing an abundance of catabolic genes. Using the whole genome information, we conducted preliminary research on key enzymes and gene clusters involved in the upstream and downstream PAH degradation pathways of strain N7, thereby inferring its degradation pathway for phenanthrene and naphthalene. This study adds to our understanding of PAH degradation in hypersaline environments and, for the first time, identifies a Pelagerythrobacter with PAH-degrading capability. Strain N7, with its high efficiency in phenanthrene degradation, represents a promising resource for the bioremediation of PAHs in hypersaline environments.

Wooded biocorridors substantially improve soil properties in low-altitude rural benchlands

This study examines soil properties in 30- and 60-year-old agricultural biocorridors and provides a comparative overview with neighbouring farmland. Both mixed and undisturbed soil samples were collected from six farmland/biocorridor study areas to assess a wide spectrum of physical, hydrophysical, chemical and biological soil properties. Biocorridor soils were characterised by higher water retention capacities, porosity, aeration and soil carbon stock, the latter increasing with depth. On the other hand, biocorridor bulk density under forest vegetation cover was lower, indicating progressive soil restoration. Slightly lower soil reactions in biocorridor soils disproved the hypothesis that nutrient-rich soils under biocorridors would form substrates with a high base cation content, leading to soil acidification. Biological activity, expressed through respiration coefficients, was generally low due to unfavourable physical conditions (clayey or silty-clay substrates), with the lowest levels in biocorridors. Nevertheless, biocorridor soil microbiota displayed more effective utilisation of organic matter as a carbon and nitrogen source, with lighter-textured soils tending to show more effective organic matter utilisation after excluding the influence of land use. Our results confirm biocorridors as an important landscape component, contributing to both soil stability and local revitalisation of soil environments and further emphasising their potential as climate-change mitigation tools in their role as carbon sinks.

Ecological and microbiological monitoring of soils in places of mass recreation

Introduction. There are presented results of a comprehensive ecological and microbiological assessment of soils located in the central part of the recreational zone of the city of Petrozavodsk, located in the middle taiga area. The study of chemical and microbiological properties of the soils of the park zone in the spatio-temporal aspect is of great importance for assessing the current state of soils and the trend of their development in conditions of anthropogenic impact, and can be the basis for urban ecological monitoring also. 
 The aim of the study is ecological and microbiological monitoring of soils in places of mass recreation of the urban population (Petrozavodsk).
 Materials and methods. The object of the study was the soils of the plots located in the central part of the city. The soils located on the territory of the Kivach Nature Reserve were selected as a control. The acid-base properties of soils, the content of heavy metals, as well as the state of the microbiotic component of soils were evaluated. Based on the data on the content of heavy metals, the degree of soil contamination with heavy metals was determined. 
 Results. Based on the data of a comprehensive study, the current state of the soils of the recreational zone of Petrozavodsk has been established. The comparative analysis of changes in chemical and microbiological properties, as well as data on the soil pollution coefficient in the space-time interval revealed a decrease in anthropogenic impact on soils. Changing the category of soil pollution is an important tool of environmental protection measures carried out on the territory of the city.
 Limitations. Work in the field of urban-ecological research is complicated by the lack of local regulatory documents that substantiate the hygienic standards for chemicals polluting the soil; limited monitoring points and work with mixed soil samples, which creates a problem of representativeness of the obtained data. 
 Conclusion. The favourable conditions for the formation of soils in the park zone affect on their soil properties, which generally meet the hygienic requirements imposed on them. The established higher indicators of the soil pollution coefficient in certain areas indicate a high anthropogenic pressure in the past, are the basis for continuing research, the need for periodic work, as well as expanding the range of soil indicators used for early diagnosis of their degradation.

PLANT COMPOSITION AND SOIL PROPERTIES DURING POSTAGROGENIC EVOLUTION IN THE CIS-BAIKAL FOREST-STEPPE ZONE

Purpose. The purpose of the study was to examine the features of the restoration of plant communities and some properties of gray forest soils, including the humus state, during their post-agrogenic transformation in the conditions of the Cis-Baikal forest-steppe zone.
 Materials and methods. The study was carried out using the post-agrogenic chronosequences, including arable land, abandoned soils of different ages, and natural cenoses (meadow and forest). Traditional methods of phytocenology were applied to study the plant composition. Mixed soil samples from three trenches were collected from the former arable layer of 0–20 cm. The content of organic carbon (Corg), total nitrogen (N), and the C/N ratio, the pH(H2O) and pH(KCL) values, as well as soil density and the reserves of Corg were determined. The statistical processing of data was performed using One Way ANOVA (Sigma Plot from Windows Version 14.0).
 Results. It was shown that plant vegetation being typical for the Baikal forest-steppe zone was recovering after the cessation of plowing. At the same time, the several ruderal species were preserved in the plant composition during a long period. This specific phenomenon could be the cause for inhibition of terminal phytocenoses formation. Along with the change in the vegetation, a significant increase in the organic carbon content was revealed in the soils of chronosequences. At the later stages of post-agrogenic succession the carbon reserves in soil were 1.5 times higher than those in arable soil. The humus content in the soils increased with age of the abandoned lands, but no cardinal changes in its qualitative composition were observed. The data indicated the stable functioning of the system of humus substances in the gray forest soils of the Baikal forest-steppe zone during their post-agrogenic evolution.
 Conclusion. The results can be used for the forecast of post-agrogenic soil changes under various scenarios of land use in conditions of the Baikal region.

Poly-γ-glutamic acid enhances the wheat yield, water use efficiency and soil physicochemical properties of the arid area in the Northwest China

ABSTRACT Poly-γ-glutamic acid (γ-PGA) is an environment-friendly super absorbent polymer that can be used as a soil conditioner, which is promising to improve crop productivity and cope with soil degradation. The objectives of this study are to study the effects of γ-PGA on soil physicochemical properties and winter wheat (Triticum aestivum L. cv. Xinong 975) production in arid region of Northwest China. According to the mass ratio of γ-PGA and soil, experiment treatments consisted of four different γ-PGA application rates, which were designated as 0 (CK), 0.05% (P0.05), 0.1% (P0.1), and 0.15% (P0.15), respectively. The mixed soil samples were uniformly filled into identical plastic pots. Each treatment had three replicates randomly distributed within 12 pots. The results indicated that γ-PGA significantly increased saturated water content by 6.3-11.5%, field capacity by 8.4-15.3%, and plant available water by 5.1-12.5% compared with the CK. γ-PGA increased soil NO3 −-N content and residue, and enhanced the proportions of soil macro-aggregates compared with the CK. γ-PGA increased winter wheat yield by 29.3-34.7%, and WUE by 21.2-33.3% compared with the CK. The main conclusion γ-PGA application amount of 0.05-0.1% can be used to improve soil physicochemical properties and winter wheat production in degraded soil.

Characterization of soils on consolidated limestone and its relations to grassland vegetation

Understanding the relations between soil features and plant responses is important for agricultural production and nature conservation. The aim of this study was to investigate the importance of the influence of soils? physical and chemical features on the composition of plant species and richness in grasslands studied on the limestone massif in eastern Serbia (Mt. Rtanj). The data set included 22 phytosociological releves, the same number of corresponding mixed soil samples (0-10 cm depth) and 8 soil profiles. Two vegetation types were distinguished by numerical classification as Saturejion montanae and Festucion valesiacae. The results of detrended correspondence analysis (DCA) indicated that the most important soil parameters affecting species composition in dry grasslands were humus, the content of calcium, soil exchange capacity and base saturation, in addition to total acidity, pH and soil depth. The communities of both vegetation types are developed on Leptosols and Phaeozems. Under similar physical and chemical conditions of the soil, the grassland vegetation exhibits differences in floristic composition.

The Soil Environment of Abandoned Charcoal Kiln Platforms in a Low-Altitude Central European Forest

This study examines the soil environment of eight charcoal kiln platforms and the neighboring soil in Czech and Bohemian low-altitude forest stands. Both mixed and undisturbed soil samples were used to assess the hydrophysical soil properties, nutrient content, cation exchange capacity, enzyme activity, and soil active carbon content, while soil color, stoniness, root density, and horizon thickness were estimated in the field. Charcoal-rich horizons had high total organic carbon concentrations and total nitrogen content (about 150% and 40% higher than in the organomineral horizons of the control plot, respectively), with total carbon stocks being higher than those in neighboring forest soils. Fine root density was highest in the charcoal-rich horizons, encouraged by high soil porosity, aeration, and favorable chemical properties. Enzyme group activity differed between individual soil horizons and kiln and control plots, with depolymerization enzyme activity highest in charcoal-rich horizons and humification enzyme activity highest in mineral horizons. Phosphatase, chitinase, and phenoloxidase activity were highest in charcoal-rich horizons, while β-glucosidase activity remained similar across horizons. After long-term abandonment, kiln sites shift from inhospitable sites to localized hotspots for plant and microbial growth, having more favorable physical, enzymatic, and chemical soil properties than the surrounding areas. This study confirmed that kiln production platforms act as microhabitat hotspots, also providing information on a wide spectrum of soil properties linked with soil microorganisms and root growth.

Influence of Pore Fluid Chemistry on Electrical Force-Dominated Fabrics of Fine-Grained Soils: Implications in Submerged Sediments

Structures to mitigate the climate change such as offshore wind farms and geological CO<sub>2</sub> sequestration would be located on coastal regions and offshores. Understanding of fine-grained soil fabrics in submerged conditions can help evaluate the safety of coastal underground constructions such as submarine excavation and slope stability. Fall cone tests for the liquid limit, grain-settling-based sedimentation tests, and ball penetration tests were conducted to investigate soil fabrics in different pore fluids with changes in ionic concentration and permittivity. Based on particle morphology and mineralogy, fine-grained soils were influenced by pore fluid chemistry. Fall cone tests showed the influence of pore fluid chemistry on uniformly mixed soil samples. Fine-grained soils that contained clay minerals such as kaolinite and bentonite showed significant liquid limit changes. Sedimentation tests and ball penetration tests induced fabrics with particle segregation and identified the type of fine-grained soils that could form gravitational force-dominated fabric or electrical force-dominated fabric during natural sedimentation process in submerged conditions.

Determination of tire wear markers in soil samples and their distribution in a roadside soil

Tire wear (TW) constitutes a significant source of microplastic in terrestrial ecosystems. It is known that particles emitted by roads can have an effect up to 100 m into adjacent areas. Here, we apply for the first-time thermal extraction desorption gas chromatography-mass spectrometry (TED-GC/MS) to determine TW in soil samples by detection of thermal decomposition products of styrene-butadiene rubber (SBR), without additional enrichment. Additionally, zinc contents were determined as an elemental marker for TW. Mixed soil samples were taken along three transects along a German motorway in 0.3, 2.0, and 5.0 m distance from the road. Sampling depths were 0–2, 2–5, 5–10, and 10–20 cm. Four fine fractions, 1 000–500, 500–100, 100–50, and <50 μm, were analyzed.TW contents based on SBR ranged from 155 to 15 898 mg kg−1. TW contents based on zinc were between 413 and 44 812 mg kg−1. Comparison of individual values of SBR and zinc reveals SBR as a more specific marker. Results confirm that most TW ends up in the topsoil within a 2 m distance.The sampling strategy resulted in representative data for a larger area. Standard deviations of quadruple TED-GC/MS determination of SBR were <10% for all grain size fractions. TED-GC/MS is a suitable analytical tool for determining TW in soil samples without the use of toxic chemicals, enrichment, or special sample preparation.

ISOLATION, IDENTIFICATION, AND DETECTION OF LIGNINOLYTIC CAPABILITY OF SOME FUNGI ISOLATED FROM SOIL SAMPLES IN EGYPT.

In the present study, twenty-seven fungal species were isolated, purified, and identified from five mixed soil samples collected from Tanta City, Gharbia Governorate, Egypt. The isolated fungal species belonging to nine genera i.e., Aspergillus, Cephalosporium, Fusarium, Penicillium, Botritrichom, Trichoderma, Alternaria, Cladosporium and Scopulariopsis, in addition to two white rot fungi Ganoderma lucidum and Lentinula edodes obtained from Mushroom Laboratory Culture Collection (MLCC), El-Giza, Egypt. The ligninolytic activities of the isolated fungi were evaluated on PDA plates containing 0.02% guaiacol as a chromogenic reagent. Out of the twenty-nine fungal species tested, only three fungi G. lucidum, L. edodes and T. harzianum (isolate 2) showed ligninolytic potential and reddish-brown color zone formed due to guaiacol oxidation. The three positive fungal strains were screened quantitively for Laccase (Lac; E.C. 1.10.3.2), Manganese dependent peroxidase (MnP; E.C. 1.11.1.13), and Lignin peroxidase (LiP; E.C. 1.11.1.14) activities. The highest total ligninase activity was recorded by G. lucidum followed by L. edodes and T. harzianum, respectively.

Soil Erodibility Analysis and Mapping in Gilgel Gibe-I Catchment, Omo-Gibe River Basin, Ethiopia

The soil erosion factor, erodibility, measures the susceptibility of soil particles to transport and detachment by erosive agents. Soil erosion and sedimentation models use soil properties and erodibility as the main input. However, in developing countries such as Ethiopia, data on soil erosion and soil-related properties are limited. For this reason, different researchers use different data sources that are adopted from a large scale and come with very different results. For this reason, the study was proposed to analyze and map the soil erodibility of the catchment area using primary data. 80 mixed soil samples were taken from the catchment with GPS coordinates and analyzed in the laboratory for soil texture class and soil organic matter. Accordingly, sandy clay loam is a dominant soil texture class covering 65% of the catchment area with 2.46% average soil organic matter, which is high in the mountainous part and lower in the lower valley of the catchment area. Most of the catchment area, which accounts for more than 78% of the area, was dominated by medium- or coarse-grained soil structure, and in the upper parts of the catchment area, 21% of the catchment area was covered with fine-grained soil structure. Similarly, 66% of the catchment area was covered with slow to moderate soil permeability, followed by slow soil permeability covering 21% of the area. Finally, the soil erodibility value of the Gilgel Gibe-I catchment was determined to be 0.046 ton h·MJ−1·mm−1 with a range of 0.032 to 0.063 ton·h·MJ−1·mm−1. In general, soils with slow permeability, high silt content, and medium- to fine-grained soil structures are the most erodible. They are conveniently separate; they tend to crust and form high drainage. Knowing this, the catchment has a moderate soil erodibility value. Thus, the study recommends evidence of land cover and the protection of arable land through suitable soil and water protection measures to improve soil permeability and soil structure.

Просторова та часова варіабельність вмісту рухомого фосфору в орному шарі ґрунтів за даними різних методів

The purpose of the article is to highlight the results of assessing the stability in time and space of the content of mobile phosphorus compounds in the soil within the arable layer on the land plots. The studies were carried out during 2018-2020 on two fields of the experimental farm "Grakovskoe" NSC "ISSAR named after O.N. Sokolovsky "in the Kharkiv region. The soil cover of one of the fields is made up of Chernozem podzolized (Chernic Phaeozem) in combination with Dark gray podzolized soil (Luvic Greyzemic Phaeozem), and the second field is Chernozem typical (Haplic Chernozem) with eroded and highly moistened varieties. Each field was divided into 24 plots, from which mixed soil samples were taken from 7 individual samples from a layer of 0–30 cm twice a season – in April–May and in October–November. On the soils of the podzolized row, a high amplitude of fluctuations in the pH values of salt was found during 3-year observations – from 4.4 to 5.2. As a result, the parameters of soil saturation with mobile phosphorus, determined by the methods of Chirikov and Machigin, were significantly different. In a field with chernozem, the typical measurement results for both methods were similar. The results of the analysis of the content of mobile phosphorus in the soils of the field according to the average values of the aggregate of individual samples did not show significant seasonal differences. However, on each of the fields, there were separate locations with higher values both according to the Chirikov method and the Machigin method, regardless of the sampling season. Along with this, in both fields there are locations where two methods of determination show different trends in the spatial distribution of the content of mobile phosphorus, which indicates the artificial nature of such heterogeneity. This confirms the hypothesis about the presence of a stable and temporarily artificial component of the spatial heterogeneity of the phosphate state of soils.

Вплив глибини локалізації мінеральних добрив на поживний режим чорнозему опідзоленого важкосуглинкового та врожайність ячменю ярого

The purpose of the research is to determine the impact of the depth of local application of mineral fertilizers on the nutrient content in the arable layer of soil and the yield of spring barley. The studies were carried out during 2018 - 2020 in a temporary small-plot experiment. Soil – chernozem podzolized loamy (Luvic Chernic Phaeozem). The application of N60P60K60 in the form of nitroammophoska or a mixture of ammophos, ammonium nitrate and potassium chloride was compared to a depth of 10-12 cm and 20-22 cm from the soil surface. The row spacing of barley crops was 15 cm; the fertilizer tape was placed at a distance of 4-5 cm away from the row. Mixed soil samples were taken from fertilizer tapes twice during the growing season of barley (in the first half of the growing season and after harvesting). The weather conditions were quite contrasting: in 2018 it was dry at the beginning of the growing season and during grain ripening, in 2019 was dry only during the formation of grain, and in 2020 - rather humid and relatively cool during almost the entire growing season. At the beginning of the growing season of barley in 2018, the highest content of mineral nitrogen in the soil was found with a shallow location of the fertilizers, but in 2019-2020 - in case fertilizer tapes at 20-22 cm from the surface. Location of fertilizer at a depth of 20-22 cm also provided a higher level of mobile phosphorus and potassium in the soil than applying at a depth of 10-12 cm. After the barley harvest, the highest accumulation of mineral nitrogen in the soil in 2018 was found with shallow application and in 2019-2020 - with deeper application. A tendency of more accumulation of chlorophyll in plants was observed with an increase in the depth of fertilization. Local application of fertilizers gave a reliable increase in yield in all variants of the experiment. However, the increase was twice as high when placing the fertilizer tape was at a depth of 20-22 cm as at a depth of 10-12 cm. Application of nitroammophoska to a depth of 20-22 cm was more effective than mixtures of simple and complex fertilizers. It was concluded that the hydrothermal conditions of the growing season and the depth of the location of fertilizers mutually affect the nutrient regime of the soil. The advantage of deep fertilization is more significant under insufficient moisture.