Ochric Epipedons Research Articles

Characterization and Taxonomy Classification of Soils of Hill Slope Land and Stream Terrace Land Located at North-Eastern Ghat Agro-Climatic Zone of Odisha, India

The present investigation was carried out to study the characterization, fertility status and taxonomic classification of some soils of North-Eastern Ghat Agro-Climatic zone of Odisha. Hill slope (pedon 1) and stream terrace land (pedon 2) two representative pedons of the Nayagarh district located in different topographic positions were studied for their physico-chemical characteristics and taxonomic classification. Results show that in pedon 1, percentage of sand, silt and clay range between 78.4 to 86.4, 3.2 to 3.4 and 10.4 to 17.4 respectively and in pedon 2, sand, silt and clay percentages range between 72 to 84, 3.2 to 7.2 and 10.8 to 18.8 respectively in different horizons. In pedons 1 and 2, pH increases along with depth from 4.80 to 5.82 and 5.80 to 7.60 respectively. Organic carbon content in pedons 1 and 2, ranges from 3.4 to 5.1 and 1.6 to 6.3 g kg-1 respectively. Cation exchange capacity decreases in pedon 1 from 13.25 to 8.66 c mol (p+) kg-1 and in pedon 2, range 7.66 to 16.65 c mol (p+) kg-1. The exchangeable sodium percentage in pedon 1 and 2, ranges from 4.53 to 9.23, and 2.56 to 6.53 per cent in different horizons respectively. The base saturation percentage in pedon 1, range from 58.11 to 98.15 per cent and in pedon 2, from 59.54 to 97.91 percent. The Hill slope (pedon 1) and stream terrace land (pedon 2) have little or no evidence of development of pedogenic horizons except ochric epipedon, therefore these soil are classified under the order Entisols. These soils have A-C profile with no distinct horizonation. Pedon 1, are classified under sub order Orthents, great group Ustorthents and sub group Typic Ustorthents. In case of pedon 2 the soils are put under the sub order Aquents, great group Fluvaquents and sub group Aeric Fluvaquents.

Pedological Characterization and Classification of Selected Soils of Morogoro and Mbeya Regions of Tanzania

This study was done in Morogoro and Mbeya regions of Tanzania to classify and characterize their respective soils. Representative pedons (SUARAT-P1 and UYOLE-P1) were dug and described using FAO guidelines clarifying morphological features, physico-chemical properties and genesis. The representative pedons were geo-referenced using Global Positioning System (GPS) receiver. A total of nine (9) genetic soil horizons were identified from both sites and samples from each horizon collected for physical and chemical analyses. Soils from both sites were very deep and topsoil moist colors ranged from hue of 7.5YR to 10YR with chroma of less than 3 in SUARAT-P1 and UYOLE-P1 pedons. Soil structure ranged from strong fine crumbs in topsoils to medium coarse sub-angular blocks in subsoils of SUARAT-P1 while UYOLE-P1 had weak fine sub-angular blocks in topsoils and subsoils. The SUARAT-P1 had sandy clay (SC) texture in topsoil and clay texture in subsoil while UYOLE-P1 had sandy loam (SL) in topsoil and sand clay loam (SCL) in subsoil. Soil reaction were slightly acid to very strongly acid in SUARAT-P1 (pH 6.54 - 4.46) whereas UYOLE-P1 were slightly acid to neutral in subsoil horizons (pH 6.35 – 7.32). Organic carbon ranged from very low to low (0.12- 0.95%) in SUARAT-P1 and from very low to medium (0.47 – 1.5%) in UYOLE-P1. Nitrogen levels were very low to low (0.05 - 0.12%) in both sites whereas available P ranged from low (0.30 mg kg-1) to medium (8.55 mg kg-1) in both pedons. CEC of SUARAT-P1 was medium ranging from 12.4 to 23.2 cmol(c) kg-1, whereas UYOLE-P1 was medium to high (15 – 34 cmol(c) kg-1). In SUARAT-P1, topsoil BS was high (> 50%) and low (< 50%) in the subsoil while UYOLE-P1 registered high BS throughout its profile depth. As diagnostic horizons for soil classification, the SUARAT-P1 had an ochric epipedon overlying a kandic horizon and classified according to USDA Soil Taxonomy as Typic Kandiustults, while UYOLE-P1 had an ochric epipedon over a cambic horizon and was named as Andic Dystrudepts corresponding respectively to Haplic Lixisols and Eutric Andic Cambisols in the WRB for Soil Resources. The results have indicated that, studied soils are less fertile with possible reconstitution through land and crop managements which include but not limited to no-tilling or conservation tillage, manuring and proper fertilizer application; residue retention, possible fallowing, liming for potential buffering of soil pH especially at SUARAT-P1 and crop rotation and intercropping with leguminous crops.

Characterization and fertility assessment of soils of Chandauli district of Eastern Uttar Pradesh for sustainable land use planning

Seven typical pedons representing major landforms in semi-arid and sub-tropical ecosystem of Chandauli district of Uttar Pradesh, viz. plains, mid lands and uplands developed from alluvium parent material under varying land uses were studied for their morphological characteristics, physical and chemical properties and soil classification. The colour of the soils ranged from light brown grey to brownish yellow red with a dominant hue of 10YR. These soils were acidic to moderately alkaline (pH 4.8 to 8.4) in reaction, non-saline, moderately deep to very deep and had isohyperthermic temperature and udic soil moisture regime. Texture and total organic carbon (TOC) ranged from silty loam to silty clay loam and 0.1 to 29.7 kg/ha respectively. Soils were medium in phosphorus (6.8 to 24.2 kg/ha) and available potassium (159 to 376 kg/ha ). All the pedons had ochric epipedon and underlain by cambic horizon (P1 to P4) within the control section and as such they come under order Inceptisols, whereas profile 5 to profile 7 have argillic horizon so they come under order Alfisols. All soils of the study area fall in agricultural land under land capability classes III and IV having limitations of slope and erosion. On the basis of major soil constraints and potentials, suitable land use plan has been suggested.

Soil taxonomy and suitability assessment on typical tobacco-planting farmlands in Guizhou, Southwest China

The classification accuracy of tobacco soil in Guizhou Province remains to be verified. In this paper, 36 typical tobacco-planting farmlands were selected in various regions of Guizhou, and soil taxonomy of the farmlands was identified according to the information of soil-forming factors, profile morphological characteristics and measured data of soil physiochemical properties. Meanwhile, the suitability of the farmlands for tobacco planting was also briefly assessed. The diagnostic horizons of the surveyed farmlands include anthrostagnic epipedon, ochric epipedon, hydragric horizon, Fe-leachic horizon, LAC-ferric horizon, argic horizon, agric horizon and cambic horizon. The diagnostic characteristics included anthrostagnic-, perudic-, aquic- and udic-soil moisture regimes, gleyic features, redoxic features, lithologic character of carbonate rocks, humic property and ferric property, etc. Their soils of the farmlands belonged to Anthrosols, Ferrosols, Argosols, Cambosols and Primosols in soil orders, and there were 4, 8, 7, 5 and 1 soil subgroups in Anthrosols, Ferrosols, Argosols, Cambosols and Primosols, respectively. Soil textures of the farmlands included sandy loam, silt loam, loam, silty clay loam, clay loam, silty clay and clay, and 29 (80.6%) farmlands were unsuitable in texture for tobacco planting due to the clayey texture; 34 (94.4%) farmlands were unsuitable in plough thickness (less than 30 cm) for tobacco planting. For soil chemical properties of plough layer, pH ranged from 4.7 to 8.5, SOM from 12.3 to 55.5 g/kg, available nitrogen from 51.5 to 257.3 mg/kg, available phosphorus from 4.3 to 99.94 mg/kg, available potassium from 95 to 885 mg/kg, available Zn from 0.04 to 3.97 mg/kg, available Mo from 0.68 to 7.45 mg/kg and available B from 0.07 to 1.76 mg/kg; all spanned from the low grades to high grades. 16 (44.4%), 17 (47.2%), 13 (26.1%), 26 (72.2%), 30 (83.3%), 26 (72.2%), 20 (55.6%) and 30 (83.3%) of the farmlands were unsuitable in pH, SOM, available nitrogen, available phosphorus, available potassium, available Zn, available Mo and available B for tobacco planting, respectively. This study provides a theoretical basis for the sustainable development of tobacco field soil conservation and flue-cured tobacco production.

Land characterization and soil-site suitability- evaluation of banana growing areas of South Gujarat, India

An investigation was carried out to evaluate the soil-site suitability and land characterization in some banana growing soils of South Gujarat. The soil belongs to Vertisols, Inceptisols and Enitisols soil order. Banana growing soil (Pedon-1) of Narmada district have ochric epipedon whereas, pedon 2, 3, 4,5, 6 and 9 are placed in order Inceptisols owing to ochric epipedon followed by cambic horizon (changes in colour, structure and texture). The presence of smectite mineralogy class, hyperthermic soil moisture regime and more than 30 per cent clay (but less than 60 per cent), pedon 7 and 8 classified as Inceptisols. In respect of land characteristics, The cumulative rating index of Jhagadia (PN2), Bardoli (PN5) and Palsana (P6) coming under highly sustainable (S2). Whereas, rest of the pedon i.e., Narmada (P1), Bharuch (PN3), Kamrej (PN4) Navsari (PN7), Jalalpore (PN8) and Valsad (PN9) are sustainable under high input (S3). Considering the soil-site suitability criteria, Bharuch (PN3), Palsana (PN6) and Jalalpore (PN8) are identified as highly suitable talukas for banana cultivation. While the Narmada (PN1), Jhagadia (PN2), Kamrej (PN4), Bardoli (PN5), Navsari (PN7) and Valsad (PN9) were categorized in moderately suitable class (S2). The suitability class can be improved if the correctable limitations (soil fertility characteristics) are altered through soil amelioration measures.

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;

English

Some soils in Ethiopia reduce plant productivity due to physical and/or chemical limitations. The morphological, physical and chemical properties of problem soils, including sodic, acidic, and saline soils, around southern Ethiopia were characterized and are described in this chapter. The intention is to characterize the soils and better understand the specific nature of the limitations. Sodic soils of Alage, acid soils of Hagereselam, and saline soils of Zeway areas were sampled to represent the problem soils. The soil properties determined included color, electrical conductivity (EC), structure, consistency, bulk density, texture, pH, organic carbon (OC), total nitrogen, available phosphorus (P) and K, exchangeable bases and available micro-nutrients. The soils had considerable heterogeneity in solum and regolith thickness, horizon depth, structural development in surface soils and subsurface horizons, pH, EC and available nutrients. The classification of these soils was made according to Soil Taxonomy and World Reference Base for Soil Resources systems. The sodic soils of Alage had high pH and sodium (Na) content, and low level of OC, available P, copper (Cu) and zinc (Zn). The epipedon was classified as an ochric and the profile also had variation in clay content down the profile to satisfy the requirements of having an argilic horizon and therefore these soils were classified as Typic Natragids. Soils of Hagereselam had very low available P. Available Cu and Zn contents were found to be at the marginal levels for production of most crops. The Hagereselam profile had an argilic horizon with umbric epipedon and was classified as Typic Paleustults. The saline soils in Zeway area had relatively high amounts of calcium and low OC. The profile was found to have ochric epipedon and these soils are classified as Typic Haplocambids. Application of fertilizer including P, Cu and Zn, and removal of sodium and salts from the soil profile may be means of improving the productivity of these soils. Application of organic amendments including manures and crop residues may also be beneficial in increasing the fertility as well as organic carbon content. &nbsp; Key words: Acidic, saline and sodic soils, reclamation, morphological, physical and chemical soil properties.

Characterization and Classification of Selected Rice Soils of Tropical Rainforest Region, Southeastern Nigeria

The study carried out in Amachi Izzi, Abakaliki, tropical rainforest region, Southeastern Nigeria was aimed at characterizing and classifying the lowland rice soils of the area. Three pedons were sunk, at the region. Results showed that soils were strongly acidic (pH <5.0), profiles 1 and 3 had low organic matter while profile 2 was moderate. Total nitrogen was also low to medium while available P was medium. Sand exhibited low variation (CV ≤15%) at Profile 2 while it indicated moderate variation (CV>15≤35%) at Profile 1 and Profile 3. Silt varied lowly (CV≤15%) at Profile 1 and moderately (CV>15≤35%) at Profile 2 and Profile 3. Clay varied highly (CV>35%) in all pedons of Abakaliki lowland soils. Base saturation varied highly (CV>35%) at Profile 1 and Profile 2 and lowly (CV≤ 15%) at Profile 3. Al saturation varied highly (CV>35%) in all pedons at Ebonyi north lowlands. Ochric epipedons were observed in pedons 1, 2 and 3 and diagnostic subsurface horizons were kandic. The temperature regime and percentage base saturation were considered at the subgroup level in the soil taxonomy. Pedons 1 and 2 were classified as Fluvaquentic Eutrudepts and Eutric Cambisol (FAO – WRB) while Pedon 3 was classified as Fluvaquentic Dystrudepts and Dystric Cambisol (FAO – WRB).

Soil formation in high elevation and permafrost areas in the Qinghai Plateau (China) .

Soil systems continuously gain and lose matter and energy even in areas where climate is too harsh to support the higher plants such as in high elevations and in permafrost environments. The purpose of this paper was to elucidate soil formation at 4 700 m asl in the Kunlun Mountains of the Qinghai (Tibet) Plateau, China. We collected twenty-six samples from three pedons developed on carbonate-rich slate and quartzitic-sandstone materials. The samples were analyzed for routine physical, chemical and mineralogical properties. Our results indicate that soil-forming processes are barely taking place in the study site as shown by pH &amp;gt; 7.0 reflecting limited decarbonation, biological activity (&amp;lt; 1.0% total C and &amp;lt; 0.05% total N), podzolization (&amp;lt;1 g Fe&lt;sub&gt;p&lt;/sub&gt;+Al&lt;sub&gt;p&lt;/sub&gt; kg&lt;sup&gt;-1&lt;/sup&gt; soil) and lessivage. The relative amounts of mica and kaolinite show no apparent change with depth suggesting minimal transformation and translocation of phyllosilicates. The most noticeable mineral transformation resulted in micaceous “flakes” and feldspathic “fragments” possibly due to thermal stress. Calcite is also observed coating the slate fragments. The soils are classified as Cryosols in the World Reference Base system and Gelisols in the Soil Taxonomy with ochric epipedon as the only diagnostic horizon indicating recent development of soils due to cold and arid environment. The results of this study show that soil-forming processes in harsh environments are manifested in the mechanical breakdown of minerals such as mica and feldspars.

Characterization and classification of soils in the Taquari river basin - Pantanal region, state of Mato Grosso do Sul, Brazil

Among the soils in the Mato Grosso do Sul, stand out in the Pantanal biome, the Spodosols. Despite being recorded in considerable extensions, few studies aiming to characterize and classify these soils were performed. The purpose of this study was to characterize and classify soils in three areas of two physiographic types in the Taquari river basin: bay and flooded fields. Two trenches were opened in the bay area (P1 and P2) and two in the flooded field (P3 and P4). The third area (saline) with high sodium levels was sampled for further studies. In the soils in both areas the sand fraction was predominant and the texture from sand to sandy loam, with the main constituent quartz. In the bay area, the soil organic carbon in the surface layer (P1) was (OC) &gt; 80 g kg-1, being diagnosed as Histic epipedon. In the other profiles the surface horizons had low OC levels which, associated with other properties, classified them as Ochric epipedons. In the soils of the bay area (P1 and P2), the pH ranged from 5.0 to 7.5, associated with dominance of Ca2+ and Mg2+, with base saturation above 50 % in some horizons. In the flooded fields (P3 and P4) the soil pH ranged from 4.9 to 5.9, H+ contents were high in the surface horizons (0.8-10.5 cmol c kg-1 ), Ca2+ and Mg² contents ranged from 0.4 to 0.8 cmol c kg-1 and base saturation was &lt; 50 %. In the soils of the bay area (P1 and P2) iron was accumulated (extracted by dithionite - Fed) and OC in the spodic horizon; in the P3 and P4 soils only Fed was accumulated (in the subsurface layers). According to the criteria adopted by the Brazilian System of Soil Classification (SiBCS) at the subgroup level, the soils were classified as: P1: Organic Hydromorphic Ferrohumiluvic Spodosol. P2: Typical Orthic Ferrohumiluvic Spodosol. P3: Typical Hydromorphic Ferroluvic Spodosol. P4: Arenic Orthic Ferroluvic Spodosol.

10.1007/s11475-008-1010-9

The effect of different rice plantation periods on the properties of selected soils on an alluvial plain was studied. Soils were sampled in fields cultivated for 6, 16, 26, and over forty years. In each rice cultivated and nonrice cultivated field, three soil profiles and six nearby auger holes were studied. This study indicated that continuous rice cultivation changed the soil moisture regime from xeric to aquic, the soil color from brown to grayish, and the surface horizons from mollic to ochric epipedon. With increasing duration of cultivation, the abundance of redoximorphic features increased and the soil structure changed from granular or blocky to massive. Therefore, the soil order changed from Mollisols to Inceptisols. No illuviation and eluviation of clay minerals occurred as a consequence of the rice cultivation. X-ray diffraction analysis showed that the clay minerals in the nonrice cultivated field were illite, vermiculite, montmorillonite, kaolinite, and chlorite, and, in the rice field, they were illite, montmorillonite, kaolinite, and chlorite, respectively. However, with increasing the period of cultivation, the amount of illite and vermiculite decreased while the amount of montmorillonite increased. The pH values of the saturated soil surface during the middle stage of rice growth shifted toward neutrality. The Eh of the surface horizons of the paddy soils under the field conditions were +40, −12, −84, and −122 mV, respectively, while the Eh in the nonpaddy soils were close to +90 mV. The amounts of organic matter and available Fe, Mn, Zn, and Cu increased, while the available K decreased in the paddy soils.

The influence of continuous rice cultivation and different waterlogging periods on the morphology, clay mineralogy, Eh, pH and K in paddy soils

The effect of different rice plantation periods on the properties of selected soils on an alluvial plain was studied. Soils were sampled in fields cultivated for 6, 16, 26, and over forty years. In each rice cultivated and nonrice cultivated field, three soil profiles and six nearby auger holes were studied. This study indicated that continuous rice cultivation changed the soil moisture regime from xeric to aquic, the soil color from brown to grayish, and the surface horizons from mollic to ochric epipedon. With increasing duration of cultivation, the abundance of redoximorphic features increased and the soil structure changed from granular or blocky to massive. Therefore, the soil order changed from Mollisols to Inceptisols. No illuviation and eluviation of clay minerals occurred as a consequence of the rice cultivation. X-ray diffraction analysis showed that the clay minerals in the nonrice cultivated field were illite, vermiculite, montmorillonite, kaolinite, and chlorite, and, in the rice field, they were illite, montmorillonite, kaolinite, and chlorite, respectively. However, with increasing the period of cultivation, the amount of illite and vermiculite decreased while the amount of montmorillonite increased. The pH values of the saturated soil surface during the middle stage of rice growth shifted toward neutrality. The Eh of the surface horizons of the paddy soils under the field conditions were +40, −12, −84, and −122 mV, respectively, while the Eh in the nonpaddy soils were close to +90 mV. The amounts of organic matter and available Fe, Mn, Zn, and Cu increased, while the available K decreased in the paddy soils.

The Influence of Continuous Rice Cultivation and Different Waterlogging Periods on Morphology, Clay Mineralogy, Eh, pH and K in Paddy Soils

The effect of different rice cultivation periods on the properties of selected soils in alluvial plain were studied in Mazandaran province (north of Iran) in 2004. Soils were sampled form 0, 6, 16, 26 and over 40 years rice cultivation fields. In each treatment three soil profiles and six nearby auger holes were studied. The present study results indicated that continuous rice cultivation have changed soil moisture regime from xeric to aquic, soil color from brown to grayish, surface horizons from mollic to ochric epipedon and soil structure changed from granular or blocky to massive. Therefore, the soil order has changed from Mollisols to Inceptisols. No illuviation and eluviation of clay minerals occurred as a consequence of rice cultivation. X-ray diffraction analysis showed that clay minerals in non-rice cultivated field were illite, vermiculite, montmorillonite, kaolinite and chlorite, but in rice field were illite, montmorillonite, kaolinite and chlorite, respectively. In contrast of montmorillonite, the amount of illite and vermiculite have been decreased by increasing periods of rice cultivation. The pH values of the saturated soil surface in six weeks past plantation have shifted toward neutrality. While Eh value of non-paddy soils were about +90 mv, surface horizons of paddy soils at field conditions had Eh value about +40, -12, -84, -122 mv, respectively. The amounts of organic matter and available Fe, Mn, Zn and Cu were increased whereas available K was decreased in paddy soils.

Control factors in the segregation of Mollisols and Aridisols of the semiarid–arid transition of Argentina

Factors that determine the segregation of soils belonging to the Mollisol or Aridisol orders have been evaluated in the semiarid-arid transition region of Argentina. The influence of edaphic parameters and precipitation on the soil organic carbon content (SOC) and color of the surficial horizons were studied on a transect of 300 km length. Results indicate that the mean annual precipitation (MAP), the contents of clay (C), silt (Si), and their summation (C + Si), as well as the color attributes value (V), chroma (Ch) and their product (VCh) showed significant linear correlations with SOC ( r = 0.63, 0.55, 0.61, 0.65, − 0.71, − 0.45 and − 0.66 respectively, p < 0.01). These correlations, however, were of low predictive value ( r 2 = 0.20 to 0.50). A multiple regression model including the variables MAP and C + Si increased the explanation of the SOC variability up to 67% ( p < 0.001). The interaction between the climatic factor and the granulometric composition of the surficial horizon determine the content and transformation of SOC, allowing the segregation of mollic or ochric epipedons defining the taxon to which each soil belongs. With the MAP > 400 mm, epipedons are mainly mollic, between 400–300 mm, the mollic or ochric epipedons are closely related to its texture, and in areas with MAP < 300 mm, epipedons are predominantly ochric, due to its low SOC contents. Color attributes were the reason to exclude about 30% of surficial horizons from the Mollisol order, despite having SOC levels higher than that established by the definition of mollic epipedon. In the studied region, SOC and color attributes used as diagnostic criteria to assign mollic epipedons are not always congruent, and soil color becomes an essential variable to differentiate Mollisols from other taxa. When we grouped soil samples by granulometric similarity, C + Si explains up to 85% of the SOC variability. At the same time, if we limit the influence of different land uses, SOC storage capacity varies between 17 to 35 Mg ha − 1 , increasing with higher precipitation and finer textures.

Formation and properties of aridic soils of Azraq Basin in northeastern Jordan

Aridisols occupy a wide and significant part of Jordan. The majority of soils in the Azraq Basin, northeastern Jordan, are aridisols. A database on aridisols and land characteristics in northeastern Jordan is needed to allow rational planning of land and water resources utilization. The objectives of this paper are to: characterize the main soil types in the area, and identify the main processes contributing to their genesis and evolution. For this purpose eight representative profiles were selected for this study and soil samples were collected and their chemical and physical properties were examined in the laboratory. The natural vegetation is desert shrubs and short grasses. The sparseness of the vegetation resulted in low SOM content and the presence of ochric epipedons in all of the studied soils. The genesis of these soils accounts for the accumulation of calcium carbonate, soluble salts, and gypsum in the subsoil. Carbonate, clay eluviation–illuviation, and salt accumulation are the dominant pedogenic processes in these soils. Silt content increased toward the surface indicating eolian activity. Clay content increased with depth indicating illuviation of clay. Clay illuviation and argillic horizon development within these soils is assumed to be a relict feature from presumably more humid climates during the Quaternary. Desert pavements cover the surfaces of these soils and provide a unique obstacle for agricultural development. The major restrictions to agricultural land use in the area are very low infiltration rate, low permeability, and high erodibility. Proper management practices should be adopted if such soils are to be cultivated.

Soils in an agricultural landscape of Jokioinen, south-western Finland

Eleven pedons in an agricultural landscape at elevations 80-130 m above sea level in Jokioinen, south-western Finland were investigated and classified according to Soil Taxonomy, the FAO-Unesco system (FAO), and the World Reference Base for Soil Resources system (WRB). The soils were related to geomorphology of the landscape which is characterized by clayey fields and forested bedrock high areas covered with glacial till. A Spodosol/Podzol was found in a coarse-sandy soil in an esker while the sandy loam in a bedrock high area soils did not have an E horizon. A man-made mollic epipedon was found in a cultivated soil which had a sandy plow layer while clayey plow layers were ochric epipedons. Cambic horizons, identified by structure and redox concentrations, were common in cultivated soils. In a heavy clay soil, small slickensides and wedge-shaped aggregates, i.e., vertic characteristics, were found. Histosols occurred in local topographic depressions irrespective of the absolute elevation. According to the three classification systems, the following catenas are recognized: Haplocryods - Dystro/Eutrocryepts -Haplocryolls - Cryaquepts - Cryosaprists (Soil Taxonomy), Podzols - Regosols - Cambisols - Histosols (FAO-Unesco), and Podzols - Cambisols - Phaeozems - Gleysols - Histosols (WRB).;

MORPHOGENESIS OF SOILS ON TWO SANDY MARINE TERRACES IN NORTHWEST FLORIDA

The objective of this research was to examine the effects of time and landscape position on the weathering and development of sandy soils in three topographic positions on Late-Pleistocene and Holocene age marine terraces in northwest Florida. The study examined three soils on the Silver Bluff marine terrace (Holocene surface) close to the Gulf of Mexico (<0.5 km) and three soils on the Pamlico marine terrace (Late-Pleistocene surface) approximately 1 km from the Gulf. A poorly drained, a moderately well drained, and an excessively drained pedon were studied on each surface. This sampling scheme resulted in a paired comparison of soils between surfaces for the three drainage classes examining the effects of time and topography (particularly, depth to water table) on organic carbon and total phosphorus (TP) contents, particle size, pH, extractable Fe and Al, and mineralogy. Results of the study indicate that the physical and chemical properties above were similar, but the morphologies were distinctly different. Similarities in particle size support a general uniformity of parent material, suggesting a homogeneous marine depositional environment. Organic carbon, pH, total P, and extractable Fe and Al did not show any trends with landscape position nor with age except those explained by morphological differences. As expected, the three soils sampled on the younger Silver Bluff terrace and closest to the Gulf of Mexico were Entisols with an ochric epipedon and no diagnostic subsurface horizons (A - C profiles). At the greater distance from the present shoreline, the older soils exhibited more morphological development: presence of a spodic (Bh) horizon or were Entisols with a colored Bw horizon.

Soil Development Differences under Larch, Cottonwood, and Prairie in North-Central North Dakota

Vegetation differences affect soil morphology. This study was conducted to determine how soil morphology, pH (CaCl2) and total and readily oxidizable soil C varied under three different types of vegetation: prairie, cottonwood (Populus deltoides), and larch (Larix siberica). The soil under the prairie vegetation is a mixed, frigid Typic Udipsamment. The soil under the cottonwood vegetation is a sandy, mixed, frigid Udorthentic Haploboroll and the larch is associated with a Typic Udipsamment. However, lighter colors and thin A horizons in the surfaces of soils under prairie vegetation reflected the presence of an ochric epipedon that is grading to mollic in character. A weak cambic that has an increase in organic C and the presence of an identifiable E horizon is evident in the soils formed under larch. These characteristics are indicative of podzolization processes attributed to the coniferous vegetation. The pH averaged 5.7 at the surface and 6.1 at a depth of 13 in. in the prairie site. Total C for the prairie site averaged 1.27% at the surface and 0.2% at 13 in. Total C in the soil under cottonwood averaged 2.3% in the surface, and 0.7% at 15 in. Soils under coniferous larch vegetation had an average pH of 5.4 in the surface and 5.9 at 15 in., and an average total C of 0.4% in the surface and 0.2% at 15 in. All soils in the cottonwood site have diagnostic mollic epipedons. The larch soils exhibit evidence of organic matter (OM) translocation and podzolization.

Soil‐Vegetation Relationships in Franciscan Terrain of Northwestern California

AbstractThis study sought to discover how soil and vegetation patterns are related in the mountains of northwestern California. Soils were compared by vegetation‐epipedon type and drainage class, with elevation as a covariate. Vegetation types were (i) open prairie, (ii) coniferinvaded prairie, (iii) oak woodland, (iv) conifer forest with umbric or mollic epipedon, and (v) conifer forest with ochric epipedon. The level of organic carbon (OC) was similar in the upper 10 cm of mineral soil under all vegetation types, but soils under forest and oak woodland had less cumulative OC and N, and a greater decrease with depth than soils under prairie. Ochric epipedons under forest had wider C/N ratios than umbric and mollic epipedons under other vegetation types. Exchangeable Ca2+ and base saturation decreased with increasing elevation. Exchangeable Ca2+ decreased with depth under oak woodland and forest, and pH decreased with depth under oak woodland. Under prairie, pH increased with depth, and Ca2+ exhibited little change. Soils under prairie and invaded prairie had lower exchangeable K+ in upper horizons than soils under forest or oak woodland. Drainage‐impaired subsoils had higher bulk density, pH, and exchangeable Ca2+ than well‐drained subsoils. Conifer invasion was restricted to well‐drained soils. Except for conifer‐invaded prairie, closely associated soil and vegetation patterns indicated that the vegetation mosaic has persisted for a long time.

Use of alloformations for definition of Holocene meander belts in the middle Amite River, southeastern Louisiana

Geomorphological studies in drainage basins of the northern Gulf of Mexico coastal plain have indicated similarities in flood-plain character and comparable influences on basin evolution. Alluvial morphology and stratigraphy can be linked to flood-plain evolution through the use of alloformations, unconformity-bounded stratigraphic units. This procedure extends classical terrace mapping concepts to conform with formally defined stratigraphic procedures. A meander belt segment of the middle Amite River valley in southeastern Louisiana was selected to test the applicability of alloformation mapping in part of a regional-scale (5,000 km 2 ) drainage basin. Three alloformations, identified as Magnolia Bridge (MAG), Denham Springs (DS), and Watson (WAT), can be differentiated by unconformable boundaries, landscape morphology, and relative pedogenic development. The valley fill consists of a lower sandy and upper silty facies. Preserved deposits consist of channel lag, point bar and scroll bar, channel fill, and overbank sequences. Lithofacies and sedimentary environments are dependent on fluvial process, and a suite of meander belt environments can be identified within each alloformation. Surface horizons of alluvial soils are all similar (ochric epipedons), but subsoil horizons are chiefly stratified parent material on the MAG (Entisols), cambic horizons on the DS (Inceptisols), and minimally developed argillic horizons on the WAT (Alfisols). Allostratigraphy provides an objective method for definition of geologic units that contain genetically related, but heterogeneous sedimentary deposits. Alluvial sediments are differentiated in a manner that successfully integrates geomorphic, sedimentologic, and pedologic data into significant stratigraphic models. This approach is applicable to a wide variety of Quaternary settings where prior stratigraphic techniques have resulted in ambiguity.