Physiographic Units Research Articles

Carbon Stock and its Management in Soils of Bhilwara District, Rajasthan

Soil organic matter is an important component that regulates most of the soil properties and serves as an indicator for assessing soil quality and climate change phenomenon. Soil resources of Bhilwara district of Rajasthan were inventorized using the IRS 1B imageries and survey of India toposheet on 1: 50, 000 scale. The district had three physiographic units viz., Eastern plain, Aravalli and Vindhyan landscape. Out of forty soil series, 22 occurred in Eastern plain, 10 in Vindhyan and 8 in Aravalli landscape. The soils of different physiographic units were evaluated for soil organic carbon (SOC) stock and soil inorganic carbon (SIC) at 0–15, 15–30, 30–50 and 50–100 cm depths. The soils of Aravali landscape, Eastern plain and Vindhyan landscape had SOC pool to the tune of 11.3, 12.1 and 14.8 Mg ha−1 at 0-15cm depth and 6.4, 9.3 and 11.6 Mg ha−1 at 15–30 cm depth, respectively. The SIC pool in these physiographic units were 4.9, 6.1 and 3.1 Mg ha−1 at 0-15cm depth and 3.5, 10.8 and 3.1 Mg ha−1 at 15–30 cm depth, respectively. Among soil orders, Vertisols (3.69% of total geographical area, TGA) sequestered highest SOC (77.1 Mg ha−1) and SIC (148.5 Mg ha−1) up to profile depth followed by Inceptisols (68.85% of TGA) and Entisols (10.32% of TGA).

Characterization and classification of sugarcane-growing soils of Central and Eastern mandals of Chittoor district in Andhra Pradesh

Soil characterization was carried out to determine the morphological, physical and chemical and mineralogical characteristics of sugarcane-growing soils of Central and Eastern mandals of Chittoor district, Andhra Pradesh. Two physiographic units were identified and designated as uplands and plains. Seven profiles were excavated with three in uplands (P1, P2 and P3) and four in plains (P4, P5, P6 and P7). The soils were characterized as follows: Hues of 10YR-2.5YR, chroma 2 to 8, value 3 to 7, sand 56.89 to 93.94%, silt 2.02 to 18.57%, clay 1.99 to 32.84%, near neutral to strongly alkaline soil reaction (pH 6.90 to 8.84), low organic carbon(0.1 to 4.8 g kg−1), moderateto high available P(7.33 to 24.50 mg kg−1), cation exchange capacity (1.05 to 28.80 cmol (p+) kg−1) and base saturation (54.29 to 91.75%). The USDA- Soil taxonomy classified the soils as fine-loamy, smectitic, isohyperthermic, Typic Ustorthents (P1 and P2) and sandy, mixed, isohyperthermic, Typic Ustorthents (P3) in uplands and sandy, smectitic, isohyperthermic, Typic Ustorthents (P4 and P5), sandy, siliceous, isohyperthermic, Typic Ustipsamments (P6) and coarse-loamy, kaolinitic, isohyperthermic, Typic Ustifluvents (P7) in plains.

Groundwater Quality Evaluation Using Multivariate Methods, in Parts of Ganga Sot Sub-Basin, Ganga Basin, India

A quantitative analytical data from the alluvial aquifers of Ganga-Sot Sub-Basin (GSSB) is subjected to multivariate statistical analysis in order to ascertain the groundwater quality characterization depending on the top soil/physiographic divisions. The matrix consists of ten variables of 34 groundwater samples collected from evenly spaced locations. The Hierarchical cluster analysis resulted in six clusters. Each cluster group is individually subjected to Principal component analysis (PCA). PCA of group A explains cumulative variance of 83%, and 95% of group of B, 82% of group C, 91% of group of D. Dissimilarity among the clusters is due to anthropogenic influence on the groundwater regime. The PCA is done for the groundwater quality data of the whole area and on the data of sub-divided area. The PCA of the whole area resulted in five components with cumulative variance of 69.19%. The area is sub divided on the basis of soil type/physiography and data falling in each sub-division is subjected to PCA. The PCA of clay loam soil/Ganga Mahwa low land resulted in five PCs explaining cumulative variance of 91%. The PCA of sandy soil/central upland data extracted four PCs with 80% of cumulative variance. The PCA of loam type of soil/Sot plain extracted three PCs explaining cumulative variance of 91.751%. The three physiographic units of the alluvium setting reflect distinct groundwater quality as manifested by the PCA. From this study it can be ascertained that PCA can be used for the characterization of groundwater quality information.

Natural variation of macrophyte vegetation of lowland streams at the regional level

Abstract In the present study, we present a synopsis of two macrophyte surveys of physiographic units in northwest Germany carried out over one decade. Data were used to test a set of hypotheses on macrophyte distribution at the regional level. Rank–frequency curves resembled the broken stick model. Twenty-one species of the 59 most frequent species occurred at high frequencies above 15%. Helophytes made up a high percentage (12 of 21) of the frequent species. Phalaris arundinacea was the most frequent species in both sampling periods. Most species showed no considerable change in frequency over time, among them the core hydrophytes. Spatial variation of species frequencies among physiographical units showed a unimodal distribution in relation to frequency. Spatial variation of frequencies of functional groups was significantly lower. Most uneven distribution among physiographical units was found in cryptogams. DCA ordinations of physiographical units showed a spatial gradient from alluvial plains to higher grounds units, which remained constant over time. CCA ordination of physiographical units in relation to environmental parameters identified two main axes, an altitudinal gradient and an alkalinity gradient. Species composition of units corresponded to the main landscape pattern of alluvial plains, glacial lowlands, and higher grounds on Mesozoic rock. Species diversity showed a complex behavior. Diverse units were found both in alluvial plains and glacial lowlands of intermediate elevation. The study may help defining regionally differentiated reference states for stream management, benchmarking indicator scores of species and avoiding application of assessment methods outside their range of applicability.

Comparing physiographic maps with different categorisations

This paper addresses the need for a robust map comparison method suitable for finding similarities between thematic maps with different forms of categorisations. In our case, the requirement was to establish the information content of newly derived physiographic maps with regards to set of reference maps for a study area in England and Wales. Physiographic maps were derived from the 90m resolution SRTM DEM, using a suite of existing and new digital landform mapping methods with the overarching purpose of enhancing the physiographic unit component of the Soil and Terrain database (SOTER). Reference maps were seven soil and landscape datasets mapped at scales ranging from 1:200,000 to 1:5,000,000. A review of commonly used statistical methods for categorical comparisons was performed and of these, the Cramer’s V statistic was identified as the most appropriate for comparison of maps with different legends. Interpretation of multiple Cramer’s V values resulting from one-by-one comparisons of the physiographic and baseline maps was facilitated by multi-dimensional scaling and calculation of average distances between the maps. The method allowed for finding similarities and dissimilarities amongst physiographic maps and baseline maps and informed the recommendation of the most suitable methodology for terrain analysis in the context of soil mapping.

Physiography of the Sicilian region (1:250,000 scale)

Physiographic maps summarize and group the landforms of a territory into homogeneous areas in terms of kind and intensity of the main geomorphological process. These maps are often produced at semi-detailed scales, while examples at the regional scale are much less common. However, because the region is the main administrative level in Europe, physiographic maps can be very useful for land planning in many fields, such as ecological studies, risk maps, and soil mapping. This work presents a methodological example of a regional physiographic map, compiled at a 1:250,000 scale, representing the whole Sicilian region, the largest of the Mediterranean islands. The physiographic units were classified according to the geomorphological processes that were identified by stereo-interpretation of aerial photographs. In addition, information from other published maps, representing geomorphological landforms, eolian deposits, anthropic terraced slopes, and landslide were used to improve the accuracy and reliability of the map.

PEDOLOGICAL STUDIES AND TREATED WASTEWATER REUSE FOR TIMBER TREES PRODUCTION IN EGYPT- EAST NEW CAIRO CITY

The present investigation soils located at desert part of east New Cairo City , south of El Kattamia –El Ain El –Sokhna new high way . The area under consideration have three physiographic units: Soil of fans and outwash plain which have three soil map units i.e. calcareous moderately deep and deepsoils, gypsiferous moderately deep to deep soils and calcigypsids moderately deep soils. Miscellaneous (Rock Soils) appear three soil map units i.e. calcareous shallow and very shallow soils, gypsiferous shallow and very shallow soils and calcigypsids shallow and very shallow soils. Miscellaneous (Rock land). The soils are classified to family level according to USDA, 2010. Current suitability study shows that soils under consideration have marginal level (S3) except soil profiles l and 6 which have moderately suitable level (S2) while soil profile 11 appear not suitable class (N1). The potential suitability was moderately suitable (S2) except soil profiles 5,7,8,10 and 11 and have marginal level (S3), while soils profile 6 has highly suitable class (S1). Concerning the available Fe, Mn, Zn, and Cu in soil are ranged between low to adequate except extractable Cu of calcigypsids soils have high level. Treats sewage water have different limitation , so, it must be used in special cases like timber trees and drip irrigation or improved surface irrigation system is suggested system for irrigation.

Analysis of the Spatial Variability of Soil Properties in Different Physiographic Units

The success of a study in geostatistics depends partially on the intrinsic characteristics of the soil. This study aimed to identify and compare the spatial variability of soil properties in different physiographic units in Great Meandros Plain, Turkey. Soil samples were collected in Yuvaca (the river terrace), Kopru (the bottom of delta on the edge of a lagoon), and Sarikemer (the back of the delta). Soils were sampled from the soil surface in 10 ha field using a regular grid with a 100 m distance in all fields. The numbers of the soil samples collected are 117 in Yuvaca and Kopru and 118 in Sarikemer. Volumetric soil moisture content (SMC), EC, and soil texture were used for geostatistical analyzing. The semivariogram parameters and kriged contour maps showed different figures due to different intrinsic characteristics of the soils. Compared with Yuvaca and Sarikemer, Kopru showed very low nugget values and high range values. For instance sand and silt percentages in Kopru resulted in very low nugget values (0.0001 ve 0.001) and high range values (805 m ve 744 m). Spherical variograms were adapted for all the properties except clay in Kopru. Although the coefficient of variation of the parameters was higher in Kopru than in the other areas, according to geostatistical calculations the lower nugget percentage and greater range indicated that there was strong spatial dependence. Dissimilarity in the fields resulted in statistically different correlations among the variables.

EVALUATION OF LAND SUITABILITY FOR AGRICULTURE IN WADI ABU SHIEH- ASSIUT GOVERNORATE.

The studied area is located between latitudes 26° 49` 26= & 26° 56`14=North and longitudes 31° 30`41= & 31° 41`48= East Fig (1).Total space of studied area is 233 km2. The aim of this study is to evaluatethe physiographic soil units including soil classification and its suitability foragriculture.The studied area has almost flat to undulating topography. The soils aredeep sand to sandy clay loam with dominance of coarse texture and high gravelcontent in most of soil profiles with some stones in the old terraces and fans andoutwash plain units. All studied soils have also low gypsum content and moderatecalcium carbonate content, whereas some soils of old terraces have calcicdiagnostic horizon. Soil salinity levels varied between non-saline into highlysaline.The physiographic units of studied soils were attributed as:(1) Old colluvial terraces. Including soil taxonomic units;- Typic Haplocalsids, Sandy skeletal, mixed, hyperthermic.(2) Wadi bottom. Including soil taxonomic units;- Typic Torriorthents Sandy skeletal, mixed, hyperthermic.(3) Wadi plains. Including soil taxonomic units;- Typic Torriorthents Sandy, mixed, hyperthermic.- Typic Torriorthents, Coarse-loamy, mixed, hyperthermic.(4) Fans and outwash plains. Including soil taxonomic units;- Typic Torriorthents Sandy-skeletal, mixed, hyperthermic.Current suitability of soil physiographic units could be categorized intothree classes as; moderately suitable (S2) for some soils in wadi bottoms and wadiplains, marginally suitable (S3) in fans and outwash plains and some soils of wadibottom and wadi plain, and not suitable (N1) for old colluvial terraces.Data of potential suitability levels reveal that the soils of wadi plain havethe highest suitability levels followed by wadi bottoms, fans and outwash plainsand old colluvial terraces, respectively.The potential land suitability for certain crops could be classified as follow;(a) Highly suitable (S1) in wadi plain soils for alfalfa and olives and in wadibottom soils for olives.(b) Moderately suitable (S2) in soils of;- Wadi plain for wheat, barley, maize, cotton, sunflower, sorghum, onion, banana,citrus, guava and mango.- Wadi bottom for maize, alfalfa, tomato, watermelon and citrus.- Old colluvial terraces and fans and outwash plains for olives.(c) Marginally suitable (S3) in soils of; - Wadi bottom for wheat, barley, cotton, sorghum, sunflower, onion, banana,guava and mango.- Fans and outwash plains for maize, cotton, sesame, sunflower, alfalfa, sorghum,onion, tomato, watermelon, citrus, guava and mango.- Old colluvial terraces for maize, sesame, sunflower, alfalfa, sorghum, tomato,watermelon, citrus and mango.(d) Not suitable (N) in soils of;- Fans and outwash plains for wheat, barley and banana.- Old colluvial terraces for wheat, barley, cotton, onion, banana and guava.

LAND SUITABILITY EVALUATION OF WADI EL ASSIUTY AREA, EASTERN DESERT OF ASSIUT GOVERNORATE, EGYPT, USING REMOTE SENSING DATA

The study area is located in the Eastern desert part of the Nile valley ofAssiut Governorate, and covers about 56670 feddans. The objective of this studyis to evaluate the soils of Wadi El Assiuty for the agricultural development usingremote sensing data. The obtained physiographic units in the study area and theassociated soils that represented by ten soil profiles were attributed as:(1) Gently undulating to undulating oldest alluvial terraces which include the taxonomicunits of Typic Clacigypsids, loamy-skeletal, mixed, hyperthermic as dominated soils,and Typic Clacigypsids, coarse-loamy, gypsic, hyperthermic, as minor soils.(2) Almost flat to gently undulating old alluvial terraces have the taxonomic units ofTypic Haplocalcids, sandy-skeletal, mixed, hyperthermic as dominant soils, whileTypic Clacigypsids, coarse-loamy, mixed,hyperthermic, as minor soils.(3) Young alluvial terraces includes Typic Haplocalcids, sandy, mixed, hyperthermic asdominant soils.(4) Wadi bottoms includes the taxonomic units of Typic Torriorthents, sandy-skeletal,mixed, hyperthermic and Typic Torriorthents, sandy, mixed, hyperthermic.(5) Dissected Rockland which are not promising area for the agricultural land use.The current and potential suitability of the studied soils for irrigatedagriculture were estimated. The obtained results indicate that all soils inits present condition have no to slight intensity of limitations for wetness,soil depth, calcium carbonate and gypsum contents. The soil textureincluding gravel, salinity and alkalinity, and soil topography are the mosteffected soil limitations. The obtained current suitability classes aredominated by the marginally suitable one (S3), with exception thecurrently not suitable (N1) of the oldest terraces soils. All the studied soilprofiles can be potentially classified as moderately suitable (S2), whichrefers to its suitability after major soil improvements.

Landscape similarity, retrieval, and machine mapping of physiographic units

We introduce landscape similarity — a numerical measure that assesses affinity between two landscapes on the basis of similarity between the patterns of their constituent landform elements. Such a similarity function provides core technology for a landscape search engine — an algorithm that parses the topography of a study area and finds all places with landscapes broadly similar to a landscape template. A landscape search can yield answers to a query in real time, enabling a highly effective means to explore large topographic datasets. In turn, a landscape search facilitates auto-mapping of physiographic units within a study area. The country of Poland serves as a test bed for these novel concepts. The topography of Poland is given by a 30m resolution DEM. The geomorphons method is applied to this DEM to classify the topography into ten common types of landform elements. A local landscape is represented by a square tile cut out of a map of landform elements. A histogram of cell-pair features is used to succinctly encode the composition and texture of a pattern within a local landscape. The affinity between two local landscapes is assessed using the Wave-Hedges similarity function applied to the two corresponding histograms. For a landscape search the study area is organized into a lattice of local landscapes. During the search the algorithm calculates the similarity between each local landscape and a given query. Our landscape search for Poland is implemented as a GeoWeb application called TerraEx-Pl and is available at http://sil.uc.edu/. Given a sample, or a number of samples, from a target physiographic unit the landscape search delineates this unit using the principles of supervised machine learning. Repeating this procedure for all units yields a complete physiographic map. The application of this methodology to topographic data of Poland results in the delineation of nine physiographic units. The resultant map bears a close resemblance to a conventional physiographic map of Poland; differences can be attributed to geological and paleogeographical input used in drawing the conventional map but not utilized by the mapping algorithm.

Linking landforms and land use to land degradation in the Middle River Njoro Watershed

Land degradation is the decline in the productive capacity of an ecosystem. This mainly occurs due to processes induced by human activities, such as deforestation, poor farming practices, or enhanced industrial growth leading to various land degradation processes such as, flooding, drought and accelerated erosion. The objective of the study was to link landforms and land uses to land degradation. Soils in the catchments were distinguished on the basis of Physiographic, parent material/ geology and soil characteristics. Eight soil mapping units were identified in the area. The validity of the identified soil mapping units were checked in the field using auger hole, mini pits, road and erosion cut observations. Representative profile pits were sighted in the major mapping units. The profile pits were described according to FAO (1977) and Kenya Soil Survey (1987). Soil classification was done according to FAO/UNESCO (1997). Soil mapping units were found to follow soil physiographic units/ land forms. Soils on mountains and hills were found to be somewhat excessively drained, shallow to moderately deep. Those from uplands and plateaus were well drained, deep to very deep. Soils on plains fell on two extremes; those that were well drained, deep to very deep and those that were imperfectly drained to poorly drained, moderately deep to very deep. Physical, chemical and biological land degradation was found to take place in the different physiographic units/ land forms at varying degrees. Soil erosion, nutrient depletion and vegetation depletion were found to be the most important degradation processes. Soil, physiographic units, soil susceptibility and hazard maps were drawn and their classes in the different landforms established.

The orchid flora of the Colombian Department of Valle del Cauca

The floristic, geographical and ecological analysis of the orchid flora of the department of Valle del Cauca are presented. The study area is located in the southwestern Colombia and it covers about 22 140km2 of land across 4 physiographic units. All analysis are based on the fieldwork and on the revision of the herbarium material. A list of 572 orchid species occurring in the department of Valle del Cauca is presented. Two species, Arundina graminifolia and Vanilla planifolia, are non-native elements of the studied orchid flora. The greatest species diversity is observed in the montane regions of the study area, especially in wet montane forest. The department of Valle del Cauca is characterized by the high level of endemism and domination of the transitional elements within the studied flora. The main problems encountered during the research are discussed in the context of tropical floristic studies.

SOIL CHARACTERISTICS AND LANDFORMS RELATIONSHIP IN THE NORTHWESTERN COAST, EGYPT

The Northwestern coast of Egypt is one of the most promising areas for agricultural development. GIS techniques were used in production and analysis digital terrain model to assess the terrain surface characteristics and producing physiographic maps. Results indicated that, six landforms were distinguished in the study area. Landforms included; basin, depression, terraces (low and high), sand plain and pediment plain. Thirty one soil profiles were dug throughout the study area to represent soil physiographic units. Soils of this area could be categorized under two orders namely, Entisols and Aridisols, and under subgroups namely classified as Gypsic Aquisalids, Typic Calcigypsids, Lithic Haplogypsids, Typic Haplocalcids, Lithic Torripsamments and Typic Torripsamments. The main diagnostic horizons of Aridisols are salic, clacic and gypsic horizons while Entisols are less developed soils.

English

A study was conducted to characterize the calcareous soils of the Askara plain in Southeastern Iran and evaluate their potential for wheat production. Sixteen soil profiles within the colluvial fan in different physiographic units were studied. Four phases of soils were identified namely the Ashkara, Dareabad, Khalandi, and Sheikhabad soils. All soils were classified as Entisols, namely Aridic Ustortents and Aridic Ustifluvents. The Ashkara soils were marginally suitable while the Dareabad and Khalandi soils were moderatelly suitable for wheat growing. The Sheikhabad soil units, however, were evaluated as S1, S2, S3 and N1 classes. The results suggested that most important limiting are high CaCO3, pH, texture and salinity as the major constraints to wheat productivity for soils of the Ashkara plain. There are about 60% of the plain that are suitable for wheat growing and only 1.15% that is not suitable due to poor moisture availability. The rest 38.85% of the plains are marginal soils.  Key words: Calcareous soils, wheat cultivation, land suitability evaluation.

Combined use of remote sensing and GIS for degradation risk assessment in some soils of the Northern Nile Delta, Egypt

The present study aimed to assess the potential of Remote Sensing (RS) and Geographic Information System (GIS) to quantify soil degradation risk in some soils of the Northern Nile Delta. Physiographic units were mapped using Landsat ETM+ image (2003) and Digital Elevation Model (DEM). The obtained map showed that the study area comprised two distinct landscapes i.e. fluvial lacustrine and flood plains. The main landforms of the area under consideration are grouped as decantation basins, levees, recent river terraces, overflow basins, man-made terraces, fish ponds and turtle backs. A simple model was designed for assessing risk of land degradation depending on the equations of soil and climatic factors. The study demonstrated that about 48.09% of the study area has undergone very high risk of chemical degradation, whereas 51.91% of the area has undergone low risk of chemical degradation. About 20.12% of the total area was characterized by high risk of physical degradation. The results indicated that the salinity, alkalinity and water logging are the main common degradation hazards.

Mapping of arsenic contamination severity in Bahraich district of Ghagra basin, Uttar Pradesh, India

Arsenic testing work has been carried out in Uttar Pradesh by UP Jal Nigam during the period 2005–2008. During this period, arsenic testing was performed using field test kits for 150,000 sources employing screening and blanket testing approach. The current paper describes the work of geographical information system (GIS) mapping in Bahraich district. The district has two physiographic units – Uprahar and Tarhar to depict highland and lowland Quarternary alluvial plains. Out of 30,216 India Mark II hand pumps in the district, arsenic testing was performed, by UP Jal Nigam for 13,812 hand pumps, out of which 7190 (52.06%) tested sources show arsenic value > 0 μg/L. Further segregation of data shows that 56.66% of affected sources fall in 10–40 μg/L category and 10.86% sources fall in >50 μg/L category. Village level mapping of affected sources at GIS platform shows arsenic concentration is more in Huzoorpur and Tajwapur blocks which lie in lowland physiographic unit.

Classification of Some Iraqi Soils Using Discriminant Analysis

This study was carried out on some Iraqi soils in different regions of the country representating various physiographic units according to previous studies in soil survey and classification in order to classify them numerically using some physical, chemical, and mineral properties as variables in numerical classification. Sixteen sites were elected in the following areas:Mosul;Diyala;Baghdad;Babil;Wasit; and Najaf. Soil individuals were classified numerically using discriminant Analysis (Hardle and Simar, 2012) to check which variables that contribute statistically significant in predicting taxonomic levels that include each soil individual according to USDA system (Soil Survey Staff, 2010). The results confirmed that the main variables that contributed to maximize accuracy in distinguishing taxonomic levels are as follows: content of sand of A horizon; content of clay of A horizon; Cation _ exchange capacity CEC of A, and C horizons; content of calcium carbonate CaCO3 of A horizon; content of Opaque minerals of C horizon; content of Amphiboles minerals of A, and C horizons; content of Pyroxene minerals of A horizon; content of Quartz mineral of A, and C horizons; and content of Feldspar minerals of A, and C horizons. Soil individuals were classified to five of taxonomic levels, these are: three soil individuals of Mosul were classified at subgroup level asTypic Calciargids, while the fourth soil individual of Mosul was classified at subgroup level as Typic Haplogypsids. Soil individuals of Diyala, Baghdad, and Babil were classified at subgroup level as TypicTorrifluvents, also one of the two soil individuals of Wasit was classified at subgroup level as TypicTorrifluvents, the other soil individual was classified at subgroup level as Typic Gypsiargids. Finally soil individual of Najaf was classified at subgroup level as Typic Calcigypsids, , which confirms the agreement of the results o f discriminant Analysis with those of USDA system.

Characterization and Evaluation of Natural Resources for Land Use Diversification Planning: A Case Study in a Block of Meghalaya Using RS & GIS Technique

Characterization and evaluation of land resources of Mawryngkneng block was carried out using IRS-P6 LISS III and LISS-IV data. Five major physiographic units namely structural hills, denudational hills, plateau and intermontane valley were identified. Visual interpretation of satellite data indicated that 32.2% of the total geographical area (TGA) is under dense forest followed by wastelands (28.8%), open forest (16.1%), cultivated area (13.6%), built up area (8.2%) and water body (0.9%). Ten soil series were tentatively identified and the soils belonged to 2 orders (Ultisols and Alfisols), 3 sub orders (Udult, Udalf and Humult), 6 great groups, 8 sub groups. The soils are moderately acidic, deep to very deep and texture varies from sandy clay loam to clay. The soils are very rich in organic carbon. The availability of nitrogen is medium to high and phosphorus availability is low to medium whereas potassium availability is low in the entire study area. The soils were grouped into land capability class II & III and the soils were moderately to marginally suitable for orange and marginally suitable for pine apple. An action plan with suggested land use and interventions has been prepared by using all land resource information generated under the study. The action plan includes areas for afforestation, intensive cultivation in the existing cropped areas with soil conservation measures like mulching, zero tillage etc. and orange and pine apple plantation in open scrub lands which are cultivable wastelands. This might help the farmers and the planner in better management of land resources for sustained productivity.

A magnetic investigation along a NE–SW transect of the Yasouj Plain, southwestern Iran

The magnetic susceptibility (χ) of soils varies with the slope position due to some factors such as texture, drainage class, and land use. Limited information is available about the magnetic susceptibility properties of semi arid regions of southwestern Iran. This study attempts to link χ and Fe oxides of the soils to landforms, soil characteristics, and land use (paddy and dryland soils) on the same parent materials. Ten representative pedons were taken along a NE–SW transect in different physiographic units in the Yasouj Plain. The results indicated that χ is determined mainly by topography and land use. In most pedons, the highest concentrations of poorly crystalline Fe (Feo) were observed in the top soil with different types of land use. Aquic condition in paddy soils seems the main cause for a significant decrease in the amount of Fed in the studied soils. Maximum concentration of pedogenic Fe (Fed) was noticed in more stable landforms with non-aquic moisture regime. Paddy soils exhibited higher Feo/Fed ratio values, suggesting that they have more poorly crystalline iron oxide phases than dryland soils. Magnetic measurements showed that the χ values of paddy soils were much lower (3.8 times) than those of dryland soils. The highest value of χ was found in the pedons located on plateau and piedmont plains and the lowest value of χ belongs to those that are located on hill and river lower terraces. A positive correlation was found between the frequency dependence of χ (χfd) and χ in paddy and dryland soils. Higher values of χfd were observed at soil surface than at deeper levels, suggesting a greater proportion of ultrafine grains.