Subsurface Diagnostic Horizons Research Articles

Characterization and classification of soils of upper Hoha sub-watershed in Assosa District, Western Ethiopia

Characterization and classification of soils is a major tool for understanding the nature and status of soils. The objective of the study was to characterize, classify and map the soils of Upper Hoha sub-watershed according to the World Reference Base for Soil Resources [1]. Seven representative pedons were opened in Upper Hoha sub-watershed at different landscape positions. Accordingly, the surface soils of Pedon 2, 3, and 7 consisted of Mollic horizons; whereas Pedon 1, 4, 5 and 6 had Umbric horizons. The subsurface diagnostic horizons identified for the opened pedons were Nitic, Cambic, Ferralic, Plinthic and Pisoplinthic horizons. Pedon 1, 2, 4, 5 and 7 contained a Nitic horizon; whereas, Pedon 3 and 6 had Cambic horizons. Also Pedon 3, 4 and 6 had Plinthic, Ferralic and Pisoplinthic subsurface horizons respectively. The surface soils of Pedon 1, 2 and 4 showed anthric properties which is affected by long-term plowing; and Pedon 2, 5 and 6 showed sideralic properties in the subsurface soils which had lower CEC <24 cmolc kg−1 clay. Pedon-3 and 7 showed abrupt textural difference in clay content between surface and subsurface horizons; in particular, Pedon-7 had colluvic materials deposition. As a result, soils of Upper Hoha sub-watershed were classified in reference soil groups of Nitisols, Cambisols and Plinthosols with their corresponding qualifiers.

Physico-chemical and mineralogical changes of lithic xerorthent soils on volcanic rocks under semi-arid ecological conditions

This study investigates the mineralogical changes and soil development processes of young soils formed on various bedrocks of volcanic origin under the same land use/land cover and climate conditions. The current study was conducted in Lithic Xerorthent soils formed on tuff, trachybasalt, and trachyandesite bedrock between Sandıklı-Şuhut districts of Afyonkarahisar. The three soil profiles excavated in the study area were classified in Entisols order based on Soil taxonomy. The primary minerals, sanidine and muscovite, and the clay minerals, smectite, kaolinite, and illite, were widely determined in three soil profiles which were named Profile I (PI), Profile II (PII), and Profile III (PIII). According to the chemical alteration index (CIA) values, which indicate weathering, the soils formed on the tuff bedrock were slightly weathered (77.04%). The chemical weathering index (CIW) in the soils' surface horizons formed on the trachybasalt and trachyandesite bedrock are classified as non-weathering rocks with 24.43% and 33.88%. Basic cations are found at high levels in the tuff bedrock. The determination of phillipsite, gismondin and calcite minerals is an indication that the mineral content of the bedrock and the bedrocks have a significant effect on soil formation. The relationship between the bedrock and the soil has been revealed. As a result of the study, it was concluded that there were significant differences in their physico-chemical characteristics, weathering rates, and mineralogical properties. However, they were characterized as young soils since they do not contain any subsurface diagnostic horizons on the volcanic bedrock under the same climatic and land use/land cover conditions.

Characterization and Classification of Some Soils Adjacent to the Southern of Al-Najaf Sea – Iraq

The study area was selected in the Najaf Governorate. It's adjacent to the southern part of Al- Najaf Sea and its area ​​(17150.5 ha), located between the longitudes 425594E and 445138E and between the Latitudes 3521842N and 3538169N (UTM), it's covered the soil types and its geomorphological units which located within the sedimentary environment of Al- Najaf Sea. The semi details soil survey was carried out to selected area for study by grade soil system and according to soil texture examination results, ten heterogeneous sites were selected and geographically determined using a GPS device. In every study area, the pedon was digger and morphologically soil units soil units descripted. The samples were then taken from each diagnostic horizon and transferred to the laboratory for some chemical analysis and physical measurements. According to the results, the soil of the study areas was classified from the level of the order to level the family according to the American system (2014) and was completed to the level of the series based on the classification system of soil proposed by Al-Aqadi (1976 and 1982). The lands of the region were classified according to the productive capacity proposed by Klingebiel and Montgomery (1961).&#x0D; The results showed that there is a variation in the morphological characteristics, whether within the single pedon or the study area, due to the effect of the topographic factor, which was reflected in the characteristics and thickness of the horizons and the nature of their arrangement and the accompanying characteristics of each horizon. The pidogenical processes, mainly washing, loss and gain, salinization have been reflected in the presence of some subsurface diagnostic horizons like the calcic, gypsic and salic horizons, with the supremacy of the primordial evolution diagnostic surface horizon, represented by the Ochric horizon. The results of the texture class showed a difference in the soil content of the soil separators indicated that there was a difference in the soil content of the soil from the main soil separators, depending on the topographical location. The results of the cartographic analysis of the texture class map for the first meter indicated the dominance of moderately fine varieties (43.6%), while the coarse texture showed lowest percentage(5.3%). The studied soils was different with carbonate content and had a different distribution with depth due to the effect of situational conditions. The values ​​of this component ranged from 145 to 500 gm.Kg-1, the state of variation in the distribution pattern of this component in the study pedons is consistent with the state of variation in the calcification activity and the observed elevation of this&#x0D; component values in the sub-surface horizons due mainly to the nature of the parent material. The soil content of the gypsum ranged between 6 to 665 gm.Kg-1, with a general trend of high soil content of this component with depth. The percent of sodium exchange percentage was ranged between 3.2 to 8.4, and did not exceed the risk limits (15%). Classification of studied area showed existence two soil orders, The majority was within Aridisols order, which formed (92.5%)from studied area. The most common great soil groups were Typic Calcigypsids(44.75%), followed by Gypsic Aquisalids (29.53%), Typic Aquisalids (5.76%), Leptic Haplogicids (6.42%) and Typic Hapiogpsids by 6.04%. The Entisol order formed 7.5%, diagnosed in great sub group under the Typic Torrifluvents. The classification of the study area lands according to the determinants of productivity indicated that the IV class had the highest percentage of the total area (48.19%), while the I class did not exceed (5.23%). The following determinants were recorded: the texture, the drainage, salinity and gypsum percentage, which emphasizes the need to take the necessary administrative measures when exploiting these agricultural lands in the future.&#x0D; &#x0D;

Optical, morphological and Physico-chemical Properties For some soils in central and northern Iraq, using a digital camera

The study was conducted in three selected sites representing the soils of three governorates of central and northern Iraq (Salah al-Din, Kirkuk, and Erbil), to determine the effect of morphological, physical and chemical characteristics of some soil genetic horizons on their spectral reflectivity using digital camera as well as Knowing the degree of soil development and classification according to the Quantitative (American) system for classifying soils, Three pedons representing these soils were excavated, the horizons were morphologically diagnosed and samples were obtained from each horizon of each pedon from the soils of the study sites to conduct some laboratory tests for the physical and chemical properties. Pictures were taken that combine dry and wet samples; In order to calculate the spectral reflectivity and RGB values using ERDAS software. The results revealed a heterogeneity in the morphological characteristics represented by the dominant color class of each pedon, with the diagnosis of the morphological features of each of the surface diagnostic horizon Ochric with the subsurface diagnostic horizons Gypsic, Calcic and Argillic. The results also found that the spectral reflectivity values of RGB were high in dry soil and decreased in the wet condition, and the lowest value of the spectral reflectivity was for the surface horizons, as it reached 44.87% on the surface horizon of the second pedon, and the highest value of the reflectivity was on the horizon Cky1 of the pedon 1, where its ratio is 72.15% ,and the reflectivity values of the red color at the red band were high in pedon Erbil as a result of the effect of iron oxides. Show the spectral and hematological differences represented by the index of brightness (value), hue and index of iron oxides The results also found that the most influential traits in these spectral indices are the dominant soil color as well as the texture of the soil represented by the content of silt and clay with moisture content, as well as the effect of the content of organic matter, iron oxides, gypsum and lime content on the surface and subsurface diagnostic horizons.

Soil Characterization and Classification for Agricultural Land Use Planning: A Study of Semi-arid Rajasthan

Based on morphological, physical, physicochemical and chemical characteristics of soil, six representative soil profiles from the Phulera tehsil of Jaipur district of Rajasthan were studied for soil characterization and classification. Results revealed that the soils of the study area were dominantly dark yellowish-brown in colour, with loamy sand texture having a higher content of sand. These soils were poor in organic carbon content (0.8 to 3.5 g kg-1). The soils were moderately alkaline (pH 7.3 to 8.3) in reaction and non-saline (EC 0.02-1.21 dS m-1). The cation exchange capacity (CEC) in most of the profiles was low (3.99 to 8.32 cmol(p+)kg-1) and calcium (Ca2+) and magnesium (Mg2+) dominated the exchange sites on the colloidal complex. All the profiles were placed under Entisol due to the absence of a diagnostic sub-surface horizon. Due to the ustic soil moisture regime, hyperthermic temperature regime, and higher sand content, the soils were classified as sandy, mixed, hyperthermic Typic Ustipsamments. On the basis of major soil constraints and potentials, suitable land use plans has been suggested.

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.

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

Distribution and properties of sandy soils in the conterminous USA – A conceptual thickness model, and taxonomic analysis

Sandy soils, as a group of soils, are unique soils. They have a specific set of physical and chemical soil properties that include rapid infiltration and conductivity, susceptibility to drought and erosion by wind, and low ability to hold water and nutrients. Sandy soils have a sandy or loamy sand texture in the fine-earth (<2 mm) fraction. They occur extensively in Florida, Nebraska, Michigan, Texas, Georgia, Wisconsin, and Minnesota. We present a conceptual thickness model for sandy soils with four depth classes: 1. soils that are sandy throughout the upper 100 cm, 2. soils that contain a sandy layer that is 50 cm or more thick over a finer-textured layer, 3. soils that have a fine-textured layer 50 cm or less over a sandy layer, and 4. soils that are sandy throughout but that are underlain by bedrock at a depth of 50 cm or less. These four classes include 2054 soil series covering nearly 600,000 km2 or 8% of the conterminous USA. There is a wide range of parent materials, but most sandy soils are formed in aeolian, marine, and outwash deposits and sandy soils occur mainly in dunes and coastal and outwash plains. Nearly three-quarters of the sandy soil area are over 100 cm deep. Sandy soils are contained primarily in the Entisol order (48% of soils on area basis), followed by Spodosols (15%) and Ultisols (13%). Nearly two-thirds of sandy soils occur in nine great groups, including Ustipsamments (12%), Torripsamments (10%), Udipsamments (7%), Quartzipsamments (7%), Haplorthods (6%), Alaquods (6%), Paleudults (5%), Kandiudults (4%), and Psammaquents (3%). As nearly half are Entisols, only 24% of the sandy soils have a diagnostic subsurface horizon. Argillic and spodic horizons occur in 18% and 13% of the soils, respectively. There is concern regarding climate change and erosion of beaches, particularly in Florida and California, the influence of sand mining on flooding in Texas, and the impact of sand mining on dunes in Michigan.

Genesis and variation spatial of Podzol in depressions of the Barreiras Formation, northeastern Espírito Santo State, Brazil, and its implications for Quaternary climate change

Variations in relief associated with pedogenetic processes promote different intensities in weathering of sediments of the Barreiras Formation and may thus lead to the formation of different soil types, like Podzols, Acrisols and Ferralsols. The Podzols of tropical regions contain important information on climate and vegetation changes that occurred mainly in late Pleistocene and Holocene; however few studied, regarding their spatial variation, that can be investigated through ground penetrating radar (GPR). The aim was to study morphological, physical, chemical, stable C isotopic properties and spatial distribution of soils within depressions of the Barreiras Formation and characterize the 14C chronology of two Podzols and their B spodic horizons, along a transect grassland to forest in northeastern Espírito Santo State, Brazil. The profiles encompass a sequence of A-E-Bhm horizons, except for P3 and P6 with histic H and A-Bt, respectively. The GPR images showed patterns corresponding to these soil horizons, and the GPR data reveal the presence of diagnostic subsurface horizons characteristic of spodic horizons with cemented layers. The influence of relief factors and original materials was observed, associated with ferrolysis and podzolisation as main actors in the genesis of soils studied. The monomorphic organic matter filling the voids evidences the processes of immobilization, illuviation and precipitation, with the genesis of the spodic horizon. The Podzols profiles of Pleistocene organic matter ages accumulated compounds of C3 plants from the vegetation cover in the B spodic horizons of the profiles P4 and P1, since at least 14,251 and 38,890 cal BP, respectively, suggesting the dominance of a humid climate at least during the studied period in the region.

Study of Morphological, Physical and Chemical Characteristics of Salt Affected Soils Using Remote Sensing Technologies at Basrah Province

This study was carried out to determine some morphological, physical and chemical properties of sedimentary salt affected soils in Basrah region east of Shatt al-Arab, and from the madina north to Abi Al-Khaseeb in the south of an area of 2819.06km2. Soil mapping units were separated using ERDAS software calculated from B4, B3, B2 and GIS spectral belts. The results of the morphological description of all the pedons showed that they represent the state of the newly formed undeveloped soils mainly composed of river sediments with the absence of diagnostic subsurface horizons. According to the prevalence of the prevailing wavelength 7.5R at drought was more than 60% of total horizons with almost equal proportions of Wavelengths 7.5YR, 5YR and 10R. Where the dominance between the wavelengths 2.5Y, 10R, 5YR and the colours ranged from Light yellow to reddish-brown heavy. Since the salinity of the soil is very important for the purposes of classification of soil and the preparation of maps and reclamation of these soils, this study aimed to study the characteristics of soils affected by salinity has separated into maps units using remote sensing technologies and geographic information systems.

Morphological diversity of chernozemic soils in south-western Poland

Abstract Diverse chernozemic soils featured by thick mollic horizon, rich in humus, dark-coloured, structural, and saturated with base cations are relatively common in the loess-belt of SW Poland. It is postulated, that most of these soils may have similar initial (chernozemic) history of thick humus horizon, related to climate conditions and vegetation in the Late Pleistocene and the Neolithic periods. However, these soils exist on various bedrocks and under different moisture conditions that led to the development accompanying features and variable classification of soils, both in Polish and international soil classifications. The aim of the paper is to presents the most important variants of loess-derived chernozemic soils of SW Poland, in relation to local conditions, which influenced soil transformation and present spatial diversification. ‘Typical’ chernozems (WRB: Calcic Chernozems), which have a mollic horizon and secondary carbonates, but are free of strong redoximorphic features, are rather uncommon in the region. Whereas, the black earths (WRB: Gleyic/Stagnic Chernozems/Phaeozems), featured by the presence of mollic horizon and strong gleyic or stagnic properties in the middle and bottom parts of the profiles, are predominant loess-derived chernozemic soils in SW Poland. Their most specific forms, developed on the clayey bedrock, are black earths with a vertic horizon (WRB: Vertic Stagnic Phaeozems). The strongly leached chernozemic soils developed over permeable subsoils, lacking carbonates and free of (strongly developed) stagnic/gleyic properties are called grey soils, often featured by the presence of subsurface diagnostic horizons cambic or luvic (WRB: Cambic/Luvic Phaeozems).

‘Palmer’ Mango Yield as Affected by Soil Class and Pedon Physicochemical Characteristics

To evaluate the variation in &amp;lsquo;Palmer&amp;rsquo; mango yield related to soil formation and soil physical and chemical properties, we studied a transect with 11 soil profiles, selected according to the altitude in a commercial orchard. Surface and subsurface diagnostic horizons were described up to two meters in depth. Soil depth, texture, structure, consistency, clay coating, cementation, and color of each horizon were morphologically determined. Undisturbed and disturbed samples were used to determine the soil total porosity, macroporosity, microporosity, density, saturated hydraulic conductivity, granulometry, total organic carbon, pH, sum of bases, and the contents of P, S, K, Na, Ca, Mg, Al, Fe, Mn, Cu, and Zn. The number of fruits (for production estimates), stem diameter, canopy area, and plant height were determined in four plants around each soil profile. Three classes of soil showed good suitability for mango cultivation: Argisol Red-Yellow Eutrophic typic, Cambisol Haplic Eutrophic Tb, and Latosol Red Yellow Eutrophic typic. The &amp;lsquo;Palmer&amp;rsquo; mango yield was correlated with the K contents, sum of bases, and pH. The low yield was a result of the low K content associated with the presence of gravel.

GENESIS AND CHARACTERISTICS OF SOILS OF THE SANTANAMOUNTAIN RANGE IN THE SERIDÓ REGION, RIO GRANDE DO NORTE, BRAZIL

ABSTRACT Rio Grande do Norte has mountain formations with edaphoclimatic conditions different from those predominating in the state, presenting deeper,acid soils, and milder climate. Among these formations, is the Santana mountain range, which is part of the Serra do Martins Formation. The objective of this work was to interpret the pedogenesis of the representative soils of the Santana mountain range through morphological, physical, and chemical characterizations of soil profiles and evaluate the effect of these attributes on the distribution of pedological forms along the landscape using multivariate analysis. Morphological, physical, and chemical analyses of seven soil profiles of the Santana mountain range were performed. The soils were classified according to the Brazilian Soil Classification System and the data subjected to multivariate analysis. The representative soil classes found were: LATOSSOLO AMARELO Distrófico argissólico; LATOSSOLO AMARELO Eutrófico argissólico; NEOSSOLO QUARTZARÊNICO Órtico típico; NEOSSOLO LITÓLICO Eutrófico fragmentário; NEOSSOLO REGOLÍTICO Eutrófico típico and CAMBISSOLO HÁPLICO Tb Eutrófico léptico. According to the analysis of the morphological attributes, the parent material had great influence on the formation of the different soil classes found in the Santana mountain range. The soil textural classes varied from sand to sandy clay loam. According to the analysis of the chemical attributes, the soil profiles presented acid reaction, great variation of base saturation, and low electrical conductivity. The multivariate analysis established groups of representative soil profiles of the Santana mountain range through the distinction of their physical and chemical attributes, mainly of subsurface diagnostic horizons.

Weathering and clay formation in semi-arid calcareous soils from Northeastern Brazil

Despite the great number of studies exploring the inter-profile genetic relationships in a catena, the microrelief and microtopographic features have been overlooked. This study investigated the role of microrelief surfaces (convex, flat and concave) on the mineral formation and pedogenesis in soils derived from limestones in NE Brazil. Soil profiles were studied in different micro-landscape surfaces, and soil samples were taken by horizon for chemical (weathering indexes) and mineralogical analyses. Mineralogy was determined in samples from diagnostic subsurface horizons, which were subjected to the proper chemical treatment for identification (X-ray diffraction - XRD) and quantification (Newmod II and Thermogravimetry - TG) of the phyllosilicates. The XRD patterns showed similar composition among the parental material of the studied profiles. The chemical also showed similar dynamics along the surfaces; however, the concave surface had soils with a higher degree of weathering, when compared to others. The clay minerals identified on the convex and flat surfaces were vermiculite, illite, smectite and kaolinite; while on the concave surface, only illite and kaolinite were found. Based on the information generated by the Newmod II, there was an increase in the amount of kaolinite towards the concave surface, from 21%, on the convex surface, to >50% of pure kaolinite crystals on the concave surface. These data were supported by the TG curves. Our results evidence that microrelief features, marked by low topographic amplitudes, are determinant for the formation and distribution of phyllosilicates in calcareous soils; and, thus, may be of key importance for predicting the occurrence of contrasting mineralogy in soils derived from calcareous rock.

Mineralogy of soils of major geomorphic units of north-eastern Haryana, India

The study was carried to determine the mineralogy of soils of different geomorphic units for providing the more detailed information needed to improve agricultural production in north-eastern part of Haryana. The soils of the study area were slightly acidic to strongly alkaline in reaction (6-9.4). The cation exchange capacity and electrical conductivity varied from 3.10-26.80 cmol (+) kg-1 and 0.16-1.20 dSm-1, respectively. In general, the soils were siliceous in nature with SiO2 ranging from 68.60 to 87.90 percent. The soil samples from surface and subsurface diagnostic horizons were studied through X-ray diffraction. In fine sand, quartz was the dominant mineral followed by feldspars, muscovite, hornblende, tourmaline, zircon, biotite, iron ores and sphene. In silt fraction, quartz was the dominant mineral followed by mica, feldspars, chlorite, kaolinite, interstratified and traces of smectite and vermiculite. Semi-quantitative estimation of clay fraction indicated that illite was the single dominant mineral in the clay fraction of these pedons, however, its quantity was less in alluvial plains (28-30 %) compared to Shiwalik hills (36-49 %). Next to illite, a high amount of smectite (14-20 %) and vermiculite (11-17 %) were observed in clays of alluvial plains of Ghaggar (recent and old) whereas in Shiwalik hills (top and valley) these minerals were detected in small amount (6-11 %). Fairly good amount of kaolinite (10-17 %) and small amount of chlorite (4-11 %) were uniformly distributed in soil clays irrespective of geomorphic units showing their detrital origin. Medium intensity broad peaks in higher range diffractograms (14-24 AËš) indicated the presence of regular and irregular interstratified minerals in old alluvial plains of Ghaggar.

Coevolution of soil and topography across a semiarid cinder cone chronosequence

Soil evolution and the development of surface and subsurface diagnostic horizons affects hydrologic partitioning of precipitation to infiltration and runoff, and the vegetative carrying capacity of landscapes, all of which affect rates of hillslope erosion. Rates of erosion, in turn, feedback on soil development by removing or preserving soil horizons. This coevolution is difficult to investigate because landscape age and initial conditions are often poorly constrained. In this paper we investigated the coevolution of the soils and hillslope topography by exploiting differences in vegetation type and density as a function of slope aspect across a semiarid basaltic cinder cone chronosequence, spanning cone ages from 1.065 to 1000kyr, in the San Francisco volcanic field (SFVF) of northern Arizona, USA. We document that soils on south-facing hillslopes exhibit systematically more aeolian-derived dust despite having higher rates of erosion. We attribute this to the fact that south-facing slopes likely had more dust-trapping vegetation cover during the glacial climates that dominated the Quaternary. The higher dust contents of soils on south-facing slopes was associated with formation of argillic horizons, lower saturated hydrologic conductivity and increased water holding capacity. Greater water retention, in turn, likely increased rates of erosion by bioturbation and freeze-thaw-driven creep in a positive feedback. Over time, dust accumulation at the hillslope point of inflection increased with age up to several hundred thousand years, then decreased with time as the cones degraded by erosion. Data suggest that approximately 200kyr of time was required before the soils developed sufficient water-holding capacity to drive in situ weathering of the basalt cinders. These results further demonstrate the importance of feedbacks among soil development, hydrology, and geomorphology in the evolution of hillslopes.

Characteristics of the soils of Ladakh region of Jammu and Kashmir

The cold arid region of Ladakh has high variability in soil characteristics. Soils of the region are quite distinct from those of other zones due to differences in climate, topography, vegetation and rocks. The paper details soil characteristics along with physiography, geology and climate of the region. Soils not only vary in physico-chemical properties but also in genesis and classification as well as microbiological properties. Such properties have been studied in typical soil profiles. By and large, the soils are shallow to very shallow in depth. They vary widely in colour, texture, structure and permeability depending upon topography and vegetation. Under the predominant influence of physical weathering, these soils usually consist of coarse materials and are often called Skeletal soils with admixtures of distinguished rock fragments, colluvial materials and screes. Most of the morphological characteristics like colour, texture and permeability seem to be inherited from the so formed regolith due to very slow rate of soil forming process. Calcareous nature of parental rocks in the form of limestone, dolomitic limestone and shale, is responsible for the genesis of soils having free CaCO3. Based on the surface and subsurface diagnostic horizons, morphological, physico-chemical and chemical characteristics of the soils, they have been classified into three main orders viz. Entisols, Inceptisols, Mollisols with occasional presence of Alfisols.

Effects of Some local Conditions on Leaching Factor of Aridisols in Kalar/Garmian, Kurdistan- Iraq

Five sites were selected in Kalar city on different topographic position. The mean annual rainfall of the study area about 280 mm with about 24.5 C° mean annual temperature. The study area used for rain feed crop production. Morphological properties of the studied pedons indicated that all pedons were developed with Ochric epipedons and Cambic and Argillic endopedons .The results of particle size distribution show a wide differences between sand and clay in surface horizons except pedon (2) because of low elevation compared with other pedons. Moreover, the results of exchangeable sodium and potassium indicate that pedons (4) and (5) had the lowest value of soil leaching factor which is an indication of the high activity of weathering and leaching processes. In another hand, the results of total element analysis has observed that the silicate ratio were high to indicate the high leaching processes which is the proof of the existence of fine materials movement particularly clay colloids, this is not merely due to the rare rainy weather conditions that are prevalent recently but is a result of wet paleoclimatic conditions, and this movement eventually occurred due to in situ factors. All soils are belonged to Aridisols order with suborders Argids and Cambidsas these soils are in aridic moisture regime include Ochric diagnostic surface horizon with Argillic and Cambic diagnostic subsurface horizons.&#x0D;

Some aspects of a multidimensional analysis of the evolution of ecological-geochemical soil state

Soil saturation index and its calculating are demonstrating multicollinear correlations between ecological-geochemical soil state and environmental circumstances. There are wood ecosystems on the research area with Phaeozem, Luvisol, Retisol and Fluvisol. We have also studied the buried soil. Their burials occurred as a result of natural processes (about 5000 BP) and as a result of human impact (about 1000 BP). Age of separate genetic horizons (from 360±50 to 1870±160 ВР) indicates soils genesis during the last stage of the Holocene – Subatlantic. In our opinion the dynamics of the climate during last stage of the Holocene is the main cause of the complex structure of the soil cover on quite small area (5 km2). Second reason is difficult geomorphological environment (rough topography). On the basis of factor analysis proved efficiency of soil saturation index by trace elements: analytical work only with the indicated index reveals an unambiguous reduce the number of determining factors (up to two) and, thus, the proportion of the variance, which is determined by two factors is 100 %. While the using in the analysis of the total content, or a mobile forms of trace elements, or of some and the others together as a combined using of content mobile forms and their mobility will lead to an increase factor up to four and the simultaneous decrease in the proportion of the variance which is due to these factors to 74–88 %. We did not find decisive influence of any factor on saturation of studied soil types by trace elements. There is always a combination of processes that contribute to the accumulation of trace elements and processes of their migration. There are illuvial and lower transition to soil parent material horizons of the background content of trace elements for all investigated soil except Fluvisol (S-1). Belong to actual places of trace elements accumulation, which is generally quite small are some lower soil horizons both buried soils and lower transition to horizon of soil parent material (in soil R-3). Thus, the upper parts of the soils which were formed during the last centuries (780 years of age to today dated) are characterized by dissipation of most of trace elements. The genetic features of Fluvisol (S-1) have confirmed very high correlation. These features are the result of the genesis of this soil under the influence both soil and sedimentation processes. This is well illustrated in the analysis of the structure of the soil profile, which have characterized by stratification (during soil formation has not resulted in the development of any diagnostic subsurface horizon) genetic horizons and the presence of buried after the accumulation of alluvial material as a humus, as a transitional horizons. Perhaps, it is partly confirmed by the radiocarbon analysis, this soil should be regarded as younger age, which obviously explains persistent inflow of fresh materials. All other soils including the buried ones were formed under various elementary soil formation processes. These processes have replacing each other in time did not stop, and the normal evolution of the soil profile took place to bottom, in contrast to the fluvisol which evolution was to upper as have happened by the fresh alluvial and probably deluvial sedimentation. Recognizing of the «normal» soil genesis process as a basis for the formation of zonal soils in the Holocene, we are interpreting Factor 1, conducted by the context of factor analysis, as the environmental conditions for such soil formation. The results of factor analysis regarding to ecological-geochemical soil state Factor 1 should be considered as the basic parameters of soils (soil organic matter, pH, indicators of soil absorbing complex, mineralogical composition and particle size distribution). Under this condition Factor 2 is associated with the processes (fluvial, sedimentation, erosion) denudation, or transfer and accumulation of different material that would cause disturbance "normal" soil genesis. For that reason ecological-geochemical soil state is determined by soil formation factors for a specific time stage and dominant conditions for some processes.

Classification and development of shallow soils (< 50 cm) in the USA

In Soil Taxonomy, soils in lithic subgroups have hard rock within 50cm of the surface. An examination of the digital databases of the USDA Natural Resources Conservation Service revealed that soils in lithic subgroups occur in 10 soil orders (excludes Oxisols and Gelisols, for which there were insufficient data) and can be ranked by area: Mollisols>Aridisols, Entisols, Inceptisols>Spodosols, Alfisols>Histosols, Ultisols, Andisols≫Vertisols. This ranking is comparable to the overall ranking of these 10 orders in the USA, except that Aridisols and Mollisols are over-represented while Alfisols and Ultisols are under-represented in lithic subgroups. Seven soil great groups account for nearly two-thirds (65%) of the soils: Calciustolls, Torriorthents, Dystrudepts, Haplargids, Haplocalcids, Haplustolls, and Argixerolls. For mineral soils, the minimum and maximum average depths to bedrock were 23 and 47cm, respectively. Although 47% of the soil series had either a cambic horizon or no diagnostic subsurface horizon, 26% had a calcic horizon, 21% an argillic horizon, and 5% a spodic horizon. Nearly two-thirds (63%) of the soils on an area basis are skeletal, i.e., contain >35% coarse fragments. More than one-quarter (26%) of the soil series have “no competing series,” meaning that they can be considered endemic to the region. Pedogenic processes in lithic soils appear to be analogous to those in soils derived from deeper unconsolidated materials, with the dominant processes being humification, calcification, argilluviation, cambisolization, and podzolization. There is abundant evidence that lithic soils are as developed—if not more developed—than nearby soils derived from deeper unconsolidated sediments. Lithic soils may be important reservoirs of SOC, clays, carbonates, and dust. In that lithic soils are often in upslope or at higher elevations, they play an integral role in landscape evolution.