Subsurface Horizons Research Articles

Geochemical Distribution of Some Heavy Metals in Agricultural Soil and Their Environmental Impacts in Kirkuk, Northern Iraq

This study is based on agricultural soil samples which are collected along three traverses (A, B, C), near the gypsum quarries located near the village of Bajwan north of Kirkuk city, to conduct a geochemical analysis and determining some heavy elements (Co, Cr, Ni, Cu, Sr, Pb, Cd) levels in the surface and subsurface soil horizons, and to indicate the potential sources of contamination with these elements. Accordingly, 30 samples were collected (six samples from travers A, five samples from travers B, and four samples from travers C) from the soil for each of the surface and subsurface levels. The results showed that the average concentrations of most studied elements increased in the subsurface soil compared to the surface soil, as a result of the influence of different geological and environmental conditions on the distribution of these elements in different soil horizons. The concentrations of the studied elements (Co, Ni, Cd) are more than their natural concentrations when compared to the natural abundance of these elements in the earth's crust, which indicates an increase in the concentration of these elements in the soil as a result of the proximity of the study area to the oil industries activities, causing the emission of high concentrations of heavy elements. As well as the traffic density of vehicles, causing the release of high concentrations of some elements. The geo accumulation factor (Igeo) indicates that most of the soil samples within different horizons of most of the heavy elements are uncontaminated to moderately contaminated, and moderately contaminated for cadmium. Also, by calculating the RI and the environmental risk factor (Er), it was found that the relative content of cadmium in soil samples recorded a considerable potential ecological risk to a high potential ecological risk. This indicates high affinity of cadmium in the soil as its infiltration into the subsurface layers.

High resolution geophysical and geospatial mapping of quaternary sediments for exploration and assessment of groundwater in Ghaziabad district, Uttar Pradesh, India

Integrated groundwater exploration studies and its evaluation were carried out deploying geology, hydrogeology, borehole lithology, hydrogeomorphology and high-resolution geophysics for mapping the subsurface horizon and delineate the potential groundwater zones in alluvium region, Ghaziabad district of Uttar Pradesh India. Electrical Resistivity Tomography survey was conducted at seven sites located in alluvium formation for understanding the subsurface geological and hydrogeological characteristics of the rock strata. We achieved significant results from the resistivity tomography models and based on the hydrogeological interpretation, it revealed the presence of groundwater potential zones at various depths mainly lying between 30 and 160 m depths with the characteristics resistivity of the aquifer is < 60 Ohm. m. Nevertheless, the interpretation of 2D resistivity models also explained and inferred that the availability of groundwater potential zone at a deeper depth, which confirmed the hydrogeological field measurements. The availability of groundwater at shallow depths <50 m is a meagre and thus the deeper aquifer should be exploited for the long term sustainability of groundwater resources. This is supported by the geospatial analysis from the results of the aquifer resistivity achieved from electrical resistivity tomography and its correlation with depths, which clearly depicted that the deeper aquifer is more productive as compared to the shallower one. Overall, the evolution of groundwater potential zonation map of the area and surroundings; clearly highlights the variation in the degree of groundwater potential zones based on the integrated analysis of the various thematic maps of the study area, which is used for the judicious planning and development of the groundwater resources in near future.

Mineralogy and genesis in an alkaline soil system in the southern Pantanal wetland, Brazil

The genesis of clays in Pantanal soils is influenced by parent material, water seasonality and elevated temperatures, resulting in soils with attributes not so common in other tropical regions. This research aimed to study the genesis of minerals in the clay fraction present in three soil profiles developed from carbonate sediments in Pantanal of the State of Mato Grosso do Sul, Brazil. Three trenches were excavated, and the soils were morphologically described and classified according to WRB in Chernozem (profiles P1 and P3) and Gleysol (P2). In addition, deformed samples from all soil horizons were sampled and used in physical, chemical, and mineralogical analyses. Clay fraction obtained from the diagnostic subsurface horizons of the profiles was submitted to identification of the mineral phases using X-ray diffraction, morphological analysis in a scanning electron microscope and microchemical analysis using energy dispersive X-ray spectroscopy. In the three profiles, the presence of interlayered minerals of kaolinite-smectite and illite-smectite; quartz and calcite in profile P3, was confirmed in the clay fraction. The clays from the three profiles presented high levels of SiO2 (ranging from 35.4 to 56.7%). The clays from profiles P1 and P2 presented high levels of Al2O3 (P1 = 24.6% and P2 = 15.2%), Fe2O3 (P1 = 14.0% and P2 = 11.8%), which suggests the formation of dioctahedral clay and illite rich in Fe. The high levels of MgO (11.1%) and Fe2O3 (7.2%) in clays of the P3 profile indicated the presence of trioctahedral Mg-smectite and illite rich in Fe. In the studied soils, the condition of moderate to imperfect drainage, water from the water table rich in cations and the alkaline environments of soils, constitutes the principal factor responsible for the current dynamics of neoformation of dioctahedral illite rich in Fe and trioctahedral Mg-smectite and dissolution of kaolinite.

Experience in conducting multi-zone hydraulic fracturing on the oilfield of PJSC «Tatneft»

The paper presents the possibilities of expanding production opportunities in the oil company PJSC Tatneft. For this purpose, the well No.xxx7g with an inclined pilot borehole was drilled at the Bavlinskoye oil field and oriented core samples were taken to study the lithological cross-section and the geological structure of the subsurface horizons. The horizontal wellbore itself is located in the dankovo-lebedyansky horizon, where multi-zone hydraulic fracturing was carried out through ports with packers there. The following methods will increase the share of recoverable oil reserves in the oldest oil-producing Volga region by starting the development of new productive horizons and increase the oil recovery factors for these reservoirs. The methods used in this work will reduce the unit costs of increasing oil production and achieve a cost-effective level of work on wells of this type. The work had its own peculiarities. One of the reasons for the difficulty in interpreting the hydraulic fracturing Minifrac (Meyer software package) was the rather long time of closing fractures in domanic deposits during the registration of pressure drop. In turn, during the minifrac analysis of the Nolte G Time Test graph showed that the fracture did not close, and therefore it is impossible to determine the closing pressure (the pressure gradient of the gap) with reliable accuracy. Note that when interpreting the flow test results, the best match of the experimental and calculated curves is achieved when using the model of a horizontal well operating a homogeneous reservoir. Also, the deterioration of the bottom-hole zone may be associated with a weak opening of the created fractures. Keywords: oil; well; hydraulic fracturing; unconventionals; fracture; core.

РАСПРЕДЕЛЕНИЕ ИЛА И СЛЕПЫШИН ПО ПРОФИЛЮ ПАХОТНЫХ ПОЧВ КАТЕН РАЗНЫХ СРОКОВ ЗЕМЛЕДЕЛЬЧЕСКОГО ОСВОЕНИЯ ЦЕНТРАЛЬНОЙ ЛЕСОСТЕПИ

The work is devoted to the study of the granulometric composition of soils of 120-year and 240-year-old agricultural development of the meadow-steppe landscape on the example of the Belgorod region. In the lateral distribution of the silt fraction contained in the arable horizon, a significant increase of its share was found in the lower parts of the soil catenae of 120-year-old arable land; as for 240-year-old arable land, lateral fluctuations of the silt fraction are less noticeable. Average values of the silt content along the slope profiles of arable land of 240 years of age showed a local maximum of silt adjacent to the subsurface horizon. An inverse correlation was found for slopes on 120-year-old arable land, namely, the fact that the percentage of the depth silt fraction increased did not lead to an increase of the same fractions in the near-arable layer. In the soil sections of the studied catenae, numerous mole rat sod piles were found, especially many of them were detected at the depth of up to one meter. The average area occupied by mole rat sod piles on the walls of the average section is 80-90% on 120-year-old arable land and 70-80% on 240-year-old arable land. Mole rat sod piles occupy 30-40% of the walls of the soil sections on the soils of the background catenae. Mole rat sod piles are more common in the soils of the catenae of the northern slopes - both for 120-year-old and 240-year-old arable land.

Patterning total mercury distribution in coastal podzolic soils from an Atlantic area: Influence of pedogenetic processes and soil components

Soils are the main Hg reservoir in the terrestrial ecosystems where it is deposited via wet or dry deposition and litterfall. Once on the soil surface, different biogeochemical routes will determine the fate of Hg and the role of terrestrial ecosystems as a Hg source or sink. The specific chemical and physical characteristics of Podzols and podzolic soils contribute to the accumulation of Hg in their illuvial horizons, avoiding its leaching to groundwater. The geographical location, state of pedogenesis, soil age, abundance of carrier phases and physical properties can affect the presence and distribution of Hg in soils. Therefore, understand and relate these factors with the behavior of Hg in Podzols and podzolic soils is key to define the role of this type of soil in the terrestrial Hg cycle. In this work, ten podzolic soil profiles were collected in an Atlantic coastal forest area of Portugal and analyzed for the main physico-chemical properties and Hg content to assess the influence of the intensity of podzolization in the Hg depth distribution. Three different patterns of Hg distribution in the studied Podzols, depending on the predominance of atmospheric deposition or the intensity of podzolization, have been defined. The pattern I showed the maximum Hg contents in the surface A horizons (12.9–23.5 µg kg−1), pattern II exhibited the highest peaks in the subsurface illuvial horizons (2.3–17.3 µg kg−1) and pattern III presented an even distribution of Hg through the soil profile. We found that dissolved organic matter (DOM) is the main carrier of Hg in the A and E horizons, whereas metal(Al, Fe)-humus complexes and/or oxyhydroxides contribute to immobilizing Hg in the illuvial horizons (Bh, Bs and Bhs). The principal component regression (PCR) analysis predicted satisfactorily the Hg distribution through soil organic matter and Al and Fe oxyhydroxides. The Hg immobilized in the subsurface layers of Podzols is retained in the long term, avoiding its migration to other components of terrestrial ecosystems where it could cause serious environmental damage such as groundwater and superficial waters.

Soil mapping, classification and morphological characteristics of the University of Benin land

This study was conducted to map, and classify the soils of University of Benin Teaching, Research and Integrated Farm site. Rigid grid soil survey method at an intensive scale was done on a 62-hectare land that produced seven mapping units. In each mapping unit, a representative pedon was sunk, described and sampled. Soil samples were analyzed using standard methods. Data generated were analyzed using descriptive statistics to determine their coefficient of variation. The r esult indicated that the soils were reddish when moist at different contrasting levels. Textural classes ranged from Loamy sand to Sandy Clay Loam while structure ranged from Single grain crumb to Sub-angular blocky. The pedons were well drained except for pedon 5, which had mottles at subsurface horizon. Means of Sand fraction ranged from ≤649 to ≥ 931 gkg-1 ; Silt ranged from ≤13.2 to ≥ 47.7gkg-1 while Clay ranged from≤ 50 to ≥ 303 gkg-1 in all the pedons; clay fraction increased with increase in depth, forming argillic horizon in pedons 1,2 and 7. pH had means ranging from ≤4.23 to ≥5.28 and recorded low variation (≤ 3.6 to ≥ 13.0 %) in all the pedons. organic carbon had means ranging from ≤ 3.3 to ≥ 36.4 gkg-1; CEC ranged from ≤ 4.85 to ≥ 16.4 cmolkg-1 while Base saturation ranged from ≤16.6 to ≥ 51%. Hence pedons 1, 2 and 7 were placed in the order Ultisols ( Acrisols); pedons 3and 4 in Entisols ( Arenosols) Pedon 4; Pedons 5and 6 in Inceptisols (Cambisols) according to USDA Soil Taxonomy and correlated with WRB.

Hydrodynamic attributes and potential hydrophobicity of a Typic Hapludult soil under secondary Atlantic forest, degraded pasture and leguminous trees, in Southeastern Brazil

Soil physical quality loss is mainly caused by compaction and soil structure deterioration. Both these processes influence water dynamic attributes such as hydraulic conductivity at saturation and sorptivity, as shown in field and laboratory studies with soil aggregates or soil samples preserved inside jackets. This study aimed: (i) to assess the link between different vegetation covers and physical attributes used to describe soil water dynamics and potential soil water repellency; and (ii) to identify whether these attributes recovered after 17-year revegetation with leguminous trees. The experimental area is located in Conceição de Macabú County, Rio de Janeiro State, Brazil. Soil aggregates were applied to tests with a miniaturized tension infiltrometer, allowing to obtain several soil hydrodynamic variables. For the surface horizon, soil hydrophobic behavior did not occur under pasture but occurred under tree covers, with the natural forest and sabiá sites being the highlights. For the subsurface horizon, the natural forest and sabiá sites were classified as non-hydrophobic and the pasture site as hydrophobic, as opposed to what was verified for the surface horizon. For both horizons, the soil under leguminous trees presented results close to those of the soil under forest, and very different from those of soil under pasture. Potential hydrophobicity levels justify the obtained opposite-to-expected hydrodynamic results, such as the lower conductivity and sorptivity occurring despite the lowest compaction and the higher conductivity and sorptivity occurring despite the highest compaction. Therefore, it was concluded that potential hydrophobicity levels affect hydrodynamic attributes and that revegetation using leguminous tree species leads to recovery of the natural soil conditions and perhaps their capacity to exert their original ecological functions.

Mineral weathering and lessivage affect microbial community and enzyme activity in mountain soils

The aim of the study was to assess if pedogenic processes such as mineral weathering and lessivage, other than organic matter accumulation, can affect soil microbial population and enzyme activities. This study examines six soil profiles located in a karst region of the North-Eastern Italian Alps and characterized by a vertical textural differentiation due to lessivage. For each soil, four pedological layers were recognized according to the dominant soil forming process: i) the top soil (Tp layer), formed by A and AB horizons, characterized by organic matter accumulation; ii) the subsurface eluviated layer (Elu layer), comprising AE and EB horizons; iii) the layer dominated by the in-situ mineral weathering (Wh layer), made by Bw horizons; iv) the deepest layer (Ls), subjected to clay illuviation and comprised by Bt horizons. In the upper layers (Tp and Elu), because of the low pH, weathering also occurred, as indicated by the presence of disordered smectite and by the high values of pedogenic Fe oxi-hydroxides to pseudo-total Fe ratio.The microbial biomass content and structure, and the enzyme activities significantly differed in the four pedological layers. The amount of microbial biomass was, as expected, most abundant in the Tp layer, where bacteria and actinomycetes abounded. Conversely, in Elu and Wh we observed a fungal-to-bacterial biomass ratio significantly higher than in Tp and Ls; in Elu, also the gram (+)/gram (−) ratio was the highest. In the upper layer, the interaction between enzymes and minerals like disordered smectite and pedogenic Fe-oxides appeared as responsible for the inhibition of the total enzyme activity per unit of organic C, and of the lipase activity. In Ls layer, where clay illuviation and high organo-minerals interaction occurred, the potential hydrolysis of organic matter was low, as revealed by the SEI/TOC ratio, the reduced lipase activity, and the inhibited activity of α-fucosidase and α-mannosidase. Even if the activity of most enzymes depends on the substrate availability, which decreases with soil depth, those involved in lipid degradation displayed the maximum activities in Elu and Wh layers, where a relative increase of the fungal population was observed. In conclusion, our findings showed that the soil functionality, expressed by the microbial community structure and enzymes activity, can vary according to organic matter–mineral interaction following the weathering and lessivage gradients along the soil profiles.

Nitrogen limitation of microbial activity in alpine tundra soils along an environmental gradient: Intra-seasonal variations and effect of rising temperature

Alpine tundra ecosystems exhibit one of the most limited availabilities of nitrogen. Furthermore, climate change may potentially stimulate not only soil organic matter decomposition, but also N mineralization; therefore, a better understanding of the response of microorganisms to increasing N availability is crucial for evaluating soil C cycling under warmer climate scenarios. In this study, we suggested that the degree of N limitation of microbial activity in the surface and subsurface soil horizons of a N-poor dwarf-shrub heath (DSH) and an N-rich graminoid meadow (GM) during a single active growing season. We conducted three series of laboratory incubations under natural (+10 °C) and high (+20 °C) temperatures with soil samples collected at the beginning, peak, and end of the growing season to examine the effects of rising temperature and intra-seasonal variations on the N limitation of microbial activity. We measured the contents of microbial C and N, microbial respiration, and the potential activity of peroxidase and β-1.4-glucosidase (enzymes that play a key role in the SOM turnover processes). It was found that the N limitation of microorganism activity could be dynamic and demonstrate temporal (depending on the season) and spatial (depending on the soil horizon) variations. The results disputed the universality of previous conclusions about the high degree of N limitation of microorganisms in alpine tundra soils, thereby suggesting that N is not always a limiting factor for microbial activity, even in the N-poor DSH. We found that warming could increase the N limitation of microorganisms, even in the N-rich GM soil, thereby limiting the effect of warming on the mineralization of soil organic matter. These data demonstrate the importance of further understanding the internal feedback mechanisms that control soil organic matter mineralization and microbial activity for accurately predicting the effects of global climate change in the Arctic.

Atterberg limits fail in recognizing fragipan horizons

Fragipan is a subsurface soil horizon characterized by high bulk density, coupled with an abundance of fine, blind pores. We hypothesized that this distinctive porosity pattern could affect the Atterberg limits, with significant deviations from those of otherwise comparable soil horizons. Additionally, longer pre-wetting times might be needed to determine the liquid and plastic limits in fragipan, due to restrictions in water movements. Based on these hypotheses, our research focused on (1) assessing the most suitable fragipan-specific sample preparation time for liquid and plastic limit determination; (2) evaluating if the Atterberg limits reflect the presence of fragic properties; (3) exploring the relationships between Atterberg limits and other relevant soil properties through Artificial Neural Networks. Fragipan horizons (F) had a slightly higher liquid limit, much higher bulk density, and specific surface area than nonfragipan (NF). The plastic limit was however comparable for F and NF. Thus, fragipans had a larger interval of plasticity, which is in contrast with slaking tests and well-known field evidence. Despite the expected differences between F and NF, three hours’ pre-wetting was enough for all samples. This might be due to the size fraction used in the analysis, more sensitive to collapse upon water saturation than bigger clods. Atterberg limits did not help in discriminating F from NF, despite the relevant differences in other soil physical properties. Neural Networks showed that the transition from the plastic to the liquid state was mainly driven by texture and specific surface area, while the plasticity interval was mainly affected by the bulk density. These results provided further insights into the mechanical properties of fragipan horizons.

Exploring the Presence of Five Rare Earth Elements in Vineyard Soils on Different Lithologies: Campo de Calatrava, Spain

The aim of the work described here was to understand the pedogeochemical signature of five rare earth elements (REEs; Ce, Nd, La, Y, and Sc) in vineyard soils in Campo de Calatrava (a unique territory with calcareous, volcanic and metamorphic rocks). The mean contents in surface horizons of Ce, Nd, La, Y, and Sc were 65.7, 32.0, 35.5, 18.8, and 13.9 mg·kg–1, respectively. In subsurface horizons the contents were Ce 62.8, Nd 31.1, La 35.7, Y 17.9, and Sc 14.4 mg·kg–1. The results show that mean contents of REEs in the area under investigation are in the order Ce &gt; Nd &gt; La &gt; Y &gt; Sc. Ce has a very high range, with a value close to 150 mg·kg–1. On the other hand, concentrations of Ce, Nd, Y, and Sc are higher in soils on volcanic material than in soils on nonvolcanic material, while only La values are lower in soils on volcanic rocks. The distributional maps of REEs in surface and subsurface horizons suggest that parent material and pedogenesis such as argillization and calcium carbonate accumulation are more important factors than the use of REE-based fertilizers, except in certain exceptional cases (consistent with a possible specific human impact after continuous fertilization).

Cryogenic soils in the Vilyuy River Valley (Yakutia)

The object of this research is the cryogenic soils of the territory located in Central Yakutia, in the middle reach of Vilyuy River nearby Makhatta Tukulan with middle-taiga larch woods landscapes. In July 2021, on the right and left banks of the Vilyuy River, twelve soil sections have been formed, which relate to turf-podzols and turf-sub-units of the illovial-ferruginous, sod and alluvial sod, psammozems and stratozems according to to classification and diagnostics of Russian soils (2004). On the slope of the river valley was also formed the soil catena that included elementary geochemical landscapes of river terraces tops and slopes surfaces, as well as middle and high floodplains on the slopes of thermofusional funnels. Soil sections were also formed in flooded beam bottom and well-drained ravine bottom, on sub-horizontal Makhatta Tukulan surface, bottoms and&amp;nbsp; slopes of thermo-suffosional funnels. The study involves 46 soil samples for measuring the&amp;nbsp;acidity&amp;nbsp;level&amp;nbsp;(pH), electric conductivity (EC), and concentration&amp;nbsp;of&amp;nbsp;total disolved solids (TDS). The explored soils are characterized with pH ranging from 2.81 to 7.78, with most common fluctuations of 5.5&amp;ndash;5.6. TDS rates were often within the limit of 10 mg L-1 and rarely exceeded that threshold, however, there were single valyes&amp;nbsp;higher than 50 mg L-1. Thus, the highest EC values (over 100 &amp;mu;S/cm) were measured in surface and subsurface horizons with high organic matter content, whereas mostly mineral horizons had typical EС values within the limit of 20 &amp;mu;S/cm.

IDENTIFICATION OF NATURAL RESOURCES IN SOME AREAS OF EL- ISMAILIYA GOVERNORATE USING REMOTE SENSING AND GIS

The current investigation aims to identifying the land and water resources in some areas of Ismailiya governorate. This study covers the soil geomorphological and pedological characteristics including classification, land capability evaluation and assessment the land suitability for certain main crops. The integration of Remote Sensing (RS) and Geographic Information System (GIS) techniques were used to perform this work. The interpretation of satellite image of the study area indicated that, there are six main identified geomorphic units including seven subunits in this area. These units are 1) Depressions, 2) Terraces (Low and High), 3) Basins (over flow basins and Decantation basins), 4) Peneplains (Low and High), 5) Sandy plains (Low, Moderate and High) and 6) Mountain (foot slope and Crest). Twenty soil profiles were selected representing these landforms. The land and site features are observed and registered. Soil profiles were dug and morphologically described. Samples were collected representing the subsequent layers in each profile as well as irrigation water samples were taken for integrated physical and chemical analysis. The studied area has almost flat topography with an elevation between -4 to 134 m. above sea level. The studied soils are deep with well drainage system. These soils have light texture mostly loamy sand with weak granular structure. All of these soils are non-saline to slightly saline and non-sodic having slightly alkaline reaction. These soils are moderately calcareous. Organic matter (OM), cation exchange capacity (CEC) and gypsum are low. These soils have low content of available macro nutrients (N, P and K). All of the studied soils haven’t any diagnostic sub-surface horizons. Therefor these soils are classified under Entisols whether as Typic Torripsaments (89.4%) or Typic Torriorthents (10.6%). The water samples taken from the Low Terraces, Low sandy plains and Peneplains showed a good quality for irrigation purposes. Water samples of the other landforms have moderate to severe salinity, sodicity and chloride hazards. According to the land capability evaluation results, about 25.7% from the studied area was fair (C3) and 74.3% was poor (C4). Land suitability evaluation for sixteen field, vegetables and fruit trees crops indicated that, soils of most the studied landforms except the Low Sandy plains are highly suitable (S1) to marginally suitable (S3) for all studied crops

Abiotic contribution to phenol oxidase activity across a manganese gradient in tropical forest soils

Phenol oxidases are a group of extracellular enzymes that catalyze the oxidation of lignin and phenolic compounds in soil organic matter. Despite their importance, little is known about these enzymes in tropical soils, particularly the extent to which minerals like manganese (Mn) oxides contribute to the measured activity. We assayed phenol oxidase activity in surface and subsurface (A and B) horizons from 15 soil profiles representing a steep Mn gradient under a lowland tropical forest in Panama. Fresh and sterilized (autoclaved) soils were assayed to determine the abiotic contribution to activity. Assays were conducted using 5 mM l-DOPA substrate in bicarbonate buffer at pH 8.5. We also determined amorphous metal oxide concentrations, soil pH, organic matter, and effective cation exchange capacity (CEC). We found little difference in phenol oxidase activity between fresh and autoclaved soils, indicating a considerable abiotic contribution to substrate oxidation. Furthermore, phenol oxidase activity was similar in surface and subsurface soils, despite markedly lower organic matter at depth. Phenol oxidase activity was correlated positively with amorphous Mn oxide concentrations (extractable Mn determined by acidic ammonium oxalate extraction), suggesting a potential mechanism of abiotic oxidation. These results have important implications for understanding carbon dynamics in tropical soils, because they suggest that (1) a portion of organic matter turnover is mediated by abiotic oxidation via Mn oxides, and (2) conventional measures of phenol oxidase activity reflect abiotic oxidation rather than the activity of enzymes synthesized by the microbial community.

GPR imaging of traffic compaction effects on soil structures

Spatial and depth variability of soil characteristics greatly influence its optimum utilization and management. Concealing nature of soil subsurface horizons has made the traditional soil investigations which rely on point information less reliable. In this study, an alternative use of ground penetrating radar (GPR)—a near-surface geophysical survey method—was tested to address the shortcomings. The focus of the study was on assessment of characteristics variability of soil layers at a test site and evaluation of effects of compaction caused by machinery traffics on soil. GPR methods utilize electromagnetic energy in the frequency range of 10 MHz and 3.0 GHz. Fourteen profiles GPR data were acquired at the test site-a farmland in Krakow, Poland. Compaction on parts of the soil was induced using tractor movements (simulating traffic effects) at different passes. Data were processed using basic filtering algorithms and attributes computations executed in Reflexw software. Attempt made in the study was on use of GPR geophysical technique for soil assessment. The method allows delineation of the soil horizons which depicts characteristic depth changes and spatial variability within the horizons. Moreover, traffic effects that caused compaction on parts of the soil horizons were discernable from the GPR profile sections. Thus, similar densification like hardpan that may develop in natural setting can be investigated using the method. The results have shown the suitability of the method for quick, noninvasive and continuous soil investigation that may also allow assessment of temporal soil changes via repeated measurement.

Variability of soil physical and hydraulic properties along a toposequence in the coastal lowlands of Rio de Janeiro

Soil physical and hydraulic properties are interdependent, and soil-use planning and management are complicated by the high variability of these attributes. The current study assessed the variability of physical and hydraulic properties of soils along a toposequence located in a forest fragment under spontaneous regeneration in the coastal lowlands of Rio de Janeiro. Four soil profiles were selected, and samples were collected from surface and subsurface horizons for determination of moisture content, bulk density, macroporosity, microporosity, hydraulic conductivity, texture, and soil resistance to penetration (measured using benchtop and field penetrometers). Exploratory and principal component analyses were performed, and descriptive parameters and Pearson’s correlation coefficients were calculated. In A horizons of profiles 3 (Planossolo) and 4 (Gleissolo), clay contents ranged from 59.0 to 577.0 g kg-1, moisture contents from 1.5 to 16.4%, and microporosity from 10.4 to 46.2%, respectively. Field- and laboratory-measured penetration resistances showed a stronger association with profile 1 (Argissolo); however, values were not sufficiently high to limit root development. The variability in soil physical and hydraulic properties in short slopes is high, mainly in terms of hydraulic conductivity, moisture, microporosity, and clay content. The greater variability of soil physical and hydraulic properties in lowland is attributed to clay and silt fractions, microporosity, and moisture content. The increment in clay content with depth increases bulk density and resistance to root penetration.

Изменение противоэрозионной стойкости орошаемых серо-коричневых почв сухой субтропической зоны Азербайджана в зависимости от давности их орошения

Изменение противоэрозионной стойкости орошаемых серо-коричневых почв сухой субтропической зоны Азербайджана в зависимости от давности их орошения

Distribution of total carbonate and iron oxides on catena at Duhok Governorate, Kurdistan Region, Iraq

The study area located at Zawita location, Duhok province, Kurdistan region, Iraq. Five pedons were digging on catena depending on the slope degree and slope aspects. Samples were air-dried, ground, and sieved using (2) mm sieve, in order to be used for physicochemical analysis. The soil texture varied from clay loam to sandy loam in the surface horizons of all pedons and became finer from the summit to foot slope in the south aspect, in contrast at the north aspect soil texture became coarser from the summit to foot slope). Study soils were less development and less differentiation of soil horizons in pedons at the summit and back slope in contrast to it at the foot slope of catena and were slightly alkaline non-saline soils. Soil organic matter in the north aspect was more than it in the south aspect. CEC in all horizons for pedon (1) at the summit was high value when compared with it for pedons at the back slope and foot slope. Studied soils consider as calcareous that have a high content of carbonate minerals as a result of the calcification pedogenic process in turn these soils have a high buffering capacity. Total carbonate at the summit, was less amount, in the surface horizon (Ah) then was gradually increased in the subsurface horizon (Bc) after that uniformity increased of carbonate distribution in soil horizons (C1st) and (C2k), whereas was decreased in surface horizons at the back slope at both aspects but in north aspect was less than it at south aspect. In surface horizons, at foot slope in both directions, total carbonate was decreased, whereas the vertical distribution indicated increasing it towards deep horizons of pedons at foot slope. Iron oxides in soil samples were fluctuated between increase and decrease with the exception of pedon (4) at the back slope in the south aspect. Part of the iron oxides was translocation downslope with runoff water and adds it to iron oxides at the foot slope and a considerable amount of it was present in the study location that is causing the change in soil color.

Anthropogenic impact on grain-size distribution and agrophysical properties of soils of cultivated rice lands of Kuban

This work reviews the relation of the grain-size distribution and impact of the use of rice rotation soils on the main agrophysical indicators of soils that determine the composition and properties of soil cover of modern delta of Kuban. The regularities of dependence between the density of the matrix soil and the grain-size distribution that consist of mineral composition of alluvial soils and rocks have been identified. The trend towards increase in soil density with increase in physical clay and silt content, as well as increase in matrix soil density has been established. No significant differences in agrophysical properties of subsurface soil horizons and underlying formations have been identified. The agrophysical indicators of soils of rice fields and boharic analogues during their agricultural use have been assessed. The hydromorphic soil-forming processes did not lead to considerable changes in agrophysical properties of alluvial formations and soils involved in rice rotation.