Diverse Parent Materials Research Articles

The nexus of clay mineralogy and soil fertility under diverse parent materials in two distinct geomorphological settings

The nexus of clay mineralogy and soil fertility under diverse parent materials in two distinct geomorphological settings

Humic substances in soils of diverse parent materials in humid tropical environment of south east nigeria.

Humic substances in soils of diverse parent materials in humid tropical environment of south east nigeria.

Erosion processes and sediment source tracing on heterogeneous slopes in the red soil region of southern China

AbstractUnderstanding erosion, sediment sources and the spatial distribution along heterogeneous slopes is essential for soil and water conservation. In this study, soils derived from nodular limestone, mud‐like limestone and limestone breccia (abbreviated as SMTL, SMDL and SLBC, respectively) were utilized to establish artificial homogeneous and heterogeneous slopes. The homogeneous slopes MTL, MDL and LBC represent SMTL‐, SMDL‐ and SLBC‐filled‐ slopes, respectively. The heterogeneous slopes were abbreviated as MTL/MDL, MDL/LBC and LBC/MTL. Rare earth elements (REEs; lanthanide, cerium and ytterbium) were used to tag soils on the upper and lower slope sections to track sediment transport and deposition. The results showed that for homogeneous slopes, the LBC slope was the most severely eroded, followed by the MDL and MTL slopes. For heterogeneous slopes, the order of erosion was LBC/MTL > MTL/MDL > MDL/LBC. Upslope sections contributed a sizable portion of the total sediment yield, ranging from 51% to 79%. Over time, the difference in the sediment contribution between the upslope and downslope regions decreased and reached equilibrium. Runoff rates on heterogeneous slopes demonstrated an inverse function (R2 > 0.75) in contrast to a logarithmic distribution (R2 > 0.87) on homogeneous slopes. Heterogeneous slopes displayed minimal intersegment variation and the absence of a consistent ordering of the magnitude of hydraulic parameters. Conversely, the hydraulic parameters of homogeneous slopes were consistently ordered across the slope sections. For sediment transport, all slopes exhibited suspension‐dominated flow with percentages greater than 89%. However, the particle size distribution of the sediment of heterogeneous slopes exhibited greater diversity and complexity because of the coexistence of distinct soils. These findings underscore the importance of customized strategies for soil and water conservation in environments characterized by diverse soil parent materials.

Soil quality estimation using environmental covariates and predictive models: an example from tropical soils of Nigeria

BackgroundInformation addressing soil quality in developing countries often depends on results from small experimental plots, which are later extrapolated to vast areas of agricultural land. This approach often results in misinformation to end-users of land for sustainable soil nutrient management. The objective of this study was to estimate the spatial variability of soil quality index (SQI) at regional scale with predictive models using soil–environmental covariates.MethodsA total of 110 composite soil samples (0–30 cm depth) were collected by stratified random sampling schemes at 2–5 km intervals across the Cross River State, Nigeria, and selected soil physical and chemical properties were determined. We employed environmental covariates derived from a digital elevation model (DEM) and Sentinel-2 imageries for our modelling regime. We measured soil quality using two approaches [total data set (TDS) and minimum data set (MDS)]. Two scoring functions were also applied, linear (L) and non-linear (NL), yielding four indices (MDS_L, MDS_NL, TDS_L, and TDS_NL). Eleven soil quality indicators were used as TDS and were further screened for MDS using principal component analysis (PCA). Random forest (RF), support vector regression (SVR), regression kriging (RK), Cubist regression, and geographically weighted regression (GWR) were applied to predict SQI in unsampled locations.ResultsThe computed SQI via MDS_L was classified into five classes: le 0.38, 0.38–0.48, 0.48–0.58, 0.58–0.68, and ge 0.68, representing very low (class V), low (class IV), moderate (class III), high (class II) and very high (class I) soil quality, respectively. GWR model was robust in predicting soil quality (R2 = 0.21, CCC = 0.39, RMSE = 0.15), while RF was a model with inferior performance (R2 = 0.02, CCC = 0.32, RMSE = 0.15). Soil quality was high in the southern region and low in the northern region. High soil quality class (> 49%) and moderate soil quality class (> 14%) dominate the study area in all predicted models used.ConclusionsStructural stability index, sand content, soil oganic carbon content, and mean weight diameter of aggregates were the parameters used in establishing regional soil quality indices, while land surface water index, Sentinel-2 near-infrared band, plane curvature, and clay index were the most important variables affecting soil quality variability. The MDS_L and GWR are effective and useful models to identify the key soil properties for assessing soil quality, which can provide guidance for site-specific management of soils developed on diverse parent materials.

Properties of soils of different lithology in the humid tropics of southeastern nigeria

This study evaluated the properties of soils developed on diverse parent materials in Ogoja Local Government Area. Five profile pits on five different parent materials were dug, morphologically delineated and described. The five parent materials were basement complex (BC), mudstone (MS), sandstone (SS), shalestone (SH) and limestone (LS). Morphologically, the soils were deep with varying color, structure, texture and consistency. The results of chemical analyses revealed that the soils have acid pH with means of 5.4, 5.4, 5.4, 5.3 and 5.4 in BC, MS, SS, SH and LS. Organic carbon was low (<15g/kg) across the parent materials while total N was slightly higher in MS, SS and LS with means of 0.04 g kg-1, 0.10 g kg-1, 0.04 g kg-1, 0.10 g kg-1 and 0.20 g kg-1 in BC, MS, SS, SH and LS accordingly. Available P was low (<8mg/kg) across the parent materials with slightly higher value recorded in SH than in other parent materials. Calcium and sodium were the dominant and the least bases respectively with mean values of 3.2 cmol/kg, 3.93 cmol/kg, 3.65 cmol/kg, 3.3 cmol/kg and 3.95 cmol/kg and 0.25 cmol/kg, 0.10 cmol/kg, 0.08 cmol/kg, 0.08 cmol/kg, 0.08 cmol/kg in BC, MS, SS, SH and LS respectively. Exchangeable bases were higher in MS than other soils. Both Al3+ and H+ contributed at the same level to acidity of the soils. Correlation analysis showed that sand correlated negatively and significantly with clay (-0.81), OC (-0.41), TN (-0.42), and Al+++ (-0.78) and positively and significantly with pH (0.72), Ca2+ (0.7), Mg2+ (0.64), K+ (0.56), ECEC (0.71) and BS (0.70). Correlation between pH and exchangeable bases, available P (0.83), ECEC (0.9) and base saturation (0.83) was significant and positive. However, most properties had negative and non-significant correlation with each other.

Effect of different pH levels on adsorption and desorption of Pb in contrasting parent materials of south eastern agro climatic zone of Nigeria

Lead adsorption and desorption at different pH levels in acid soils of diverse parent materials were evaluated. The soil samples were collected from soils underlain by olivine basalt (Ikom), coastal plain sands (Ihiagwa) and false bedded sandstone (Ishiagu). The collected samples were air -dried, crushed, sieved with a 2 mm sieve and analyzed in the laboratory. The adsorption of lead (Pb) increased with increasing solution pH. At pH 3, 4 and 6, the adsorption of Pb was higher in false bedded sandstone than the other soils. At pH 5, adsorption of Pb was higher in olivine basalt than the other soils. Except at pH 3, desorption of Pb was higher in coastal plain sands than the other soils. At the same time it was lower in false bedded sand stone than the other soils at all pH. At pH 5, adsorption of Pb had a significant positive correlation with organic matter (r =0.774481, p≤ 0.05), while at pH 6, it had a significant positive correlation with soil pH (r =0.738401, p ≤ 0.05). Organic matter and soil pH are the most critical soil properties affecting adsorption-desorption of Pb on these soils.

Potentially Toxic Trace Elements in the Urban Soils of Santiago de Compostela (Northwestern Spain)

With the objective of increasing information inorganic pollutants in urban soils in Spain, we studied the presence of Cu, Pb, Zn, Ni, Cr, and As in 55 soils in the city of Santiago de Compostela (northwestern Spain). The soils were developed over diverse parent materials (granites, gneiss, schists, and amphibolites) and present different land uses, urban grasslands, urban forests, urban allotment gardens, and peri-urban agricultural soils. Total trace element concentrations, analyzed by XRF of ground samples, were correlated to physicochemical properties of the soils, and the influence of land use, lithology, and location on the degree of pollution was explored. In most soils, trace element concentrations followed the sequence Zn (55–484 mg kg−1) > Pb (20–566 mg kg−1) > Cr (17–277 mg kg−1) > Cu (17–188 mg kg−1) > As (13–205 mg kg−1) > Ni (11–91 mg kg−1). The concentrations were overall higher than regional backgrounds, but not high enough to class the soils as contaminated according to the Spanish regulation. Accordingly, the geoaccumulation index values indicate that most soils present low to moderate pollution levels. Among the elements studied, Cu, Pb, and Zn were correlated between them, with their highest concentrations happening in soils of the green areas in the city center; Cr and Ni concentrations were related to lithology of the parent material, with the highest concentrations in soils developed over amphibolite; finally, As concentrations are higher in two precise points without a clear connection to a known source of pollution.

Heavy metals in agricultural soils developed on diverse parent materials in Cross River State, Nigeria

ABSTRACT This study investigated the current state and pollution loads of heavy metals in soils developed on diverse parent materials in southeastern Nigeria. Cu, Mn, Zn, Fe and Al were analyzed to estimate pollution loads and ecological risk of the area. The result showed soils developed on granite gneiss to have a higher concentration (measured in mg kg−1) of Cu (1.79), Mn (78.39) and Zn (28.53), while soils developed on Biotite hornblende gneiss and quartz-mica-schist had a higher concentration of Fe (≥18) compared with other parent materials. The contamination factor for Fe, Zn, Mn and Cu was low, whereas Al was moderately to considerably contaminated except for soils in S2 (0.362), S3 (0.662), S6 (0.142), S9 (0.661), S11 (0.803) and S15 (0.499). The result of the pollution load index indicated an unpolluted condition (PLI < 1). Excluding Al, the soils were practically uncontaminated with Zn, Cu, Fe and Mn, based on the Geo-accumulation index and Quartz-mica-schist was enriched by Zn in S6 (1.325) and showed low ecological risk (Er < 40) and (IR < 150). Hence, the soils in the studied communities are still in a safe state to be used for crop cultivation without any fear of metal contamination.

Using Variable Selection and Wavelets to Exploit the Full Potential of Visible–Near Infrared Spectra for Predicting Soil Properties

In soil spectroscopy a series of strategies exists to optimise multivariate calibrations. We explore this issue with a set of topsoil samples for which we estimated soil organic carbon (OC) and total nitrogen (N) from visible–near infrared (vis–NIR) spectra (350–2500 nm). In total, 172 samples were collected to cover the soil heterogeneity in the study area located in western Rhineland-Palatinate, Germany. There, soils with varying properties developed from very diverse parent materials, e.g., ranging from very acidic sandstone to dolomitic marl. We defined four sample sets each of a different size and heterogeneity. Each set was subdivided into a calibration and a validation set. The first strategy that we tested to improve prediction accuracies was spectral variable selection using competitive adaptive reweighted sampling (CARS) and iteratively retaining informative variables (IRIV), both in combination with partial least squares regression (PLSR). In addition, continuous wavelet transformation (CWT) with the Mexican Hat wavelet was applied to decompose the measured spectra into multiple scale components (dyadic scales 21−25) and thus to represent the high and low frequency features contained in the spectra. CARS was then applied to select wavelet coefficients from the different scales and to introduce them in the PLSR approach (CWT-CARS-PLSR). Regarding prediction power, CWT-CARS-PLSR outperformed the other approaches. For the smallest data set with 30 validation samples, prediction accuracy for OC increased from approximately quantitative with full spectrum-PLSR ( r2 = 0.81, residual prediction deviation ( RPD) = 2.27) to excellent when using wavelet decomposition and CARS-PLSR ( r2 = 0.93, RPD = 3.60). For N, predictions improved from unsuccessful ( r2 = 0.63, RPD = 1.36) to approximately quantitative ( r2 = 0.84, RPD = 2.03). In case of OC, predictions were worst for the largest dataset with 57 validation samples: CWT-CARS-PLSR achieved approximately quantitative predictions ( r2 = 0.82, RPD = 2.31), whereas full spectrum-PLSR provided estimates that allowed only separating between high and low values ( r2 = 0.72, RPD = 1.88). Accuracy of N estimation for this dataset using CWT-CARS-PLSR was also approximately quantitative. Concerning the tested spectral variable selection techniques, both methods provided similar results in the prediction. The application of IRIV was limited due to long processing times.

Ca, Sr and Ba stable isotopes reveal the fate of soil nutrients along a tropical climosequence in Hawaii

Nutrient biolifting is an important pedogenic process in which plant roots obtain inorganic nutrients such as phosphorus (P) and calcium (Ca) from minerals at depth and concentrate those nutrients at the surface. Here we use soil chemistry and stable isotopes of the alkaline earth elements Ca, strontium (Sr) and barium (Ba) to test the hypothesis that biolifting of P has been an important pedogenic process across a soil climosequence developed on volcanic deposits at Kohala Mountain, Hawaii. The geochemical linkage between these elements is revealed as generally positive site-specific relationships in soil mass gains and losses, particularly for P, Ba and Ca, using the ratio of immobile elements titanium and niobium (Ti/Nb) to link individual soil samples to a restricted compositional range of the chemically and isotopically diverse volcanic parent materials. At sites where P is enriched in surface soils relative to abundances in deeper soils, the isotope compositions of exchangeable Ca, Sr and Ba in the shallowest soil horizons (<10cm depth) are lighter than those of the volcanic parent materials and trend toward those of plants growing on fresh volcanic deposits. In contrast the isotope composition of exchangeable Ba in deeper soil horizons (>10cm depth) at those sites is consistently heavier than the volcanic parent materials. The isotope compositions of exchangeable Ca and Sr trend toward heavier compositions with depth more gradually, reflecting increasing leakiness from these soils in the order Ba<Sr<Ca and downward transfer of light biocycled Ca and Sr to deeper exchange sites. Given the long-term stability of ecosystem properties at the sites where P is enriched in surface soils, a simple box model demonstrates that persistence of isotopically light exchangeable Ca, Sr and Ba in the shallowest soil horizons requires that the uptake flux to plants from those near-surface layers is less than the recycling flux returned to the surface as litterfall. This observation implicates an uptake flux from an additional source which we attribute to biolifting. We view the heavy exchangeable Ba relative to soil parent values in deeper soils at sites where P is enriched in surface soils, and indeed at all but the wettest site across the climosequence, to represent the complement of an isotopically light Ba fraction removed from these soils by plant roots consistent with the biolifting hypothesis. We further suggest that decreasing heaviness of depth-integrated exchangeable Ba in deeper soils with increasing median annual precipitation across the climosequence reflects greater reliance on shallow nutrient sources as site water balance increases. While the Ca, Sr and Ba isotopes considered together were useful in confirming an important role for nutrient biolifting across the climosequence, the Ba isotopes provided the most robust tracer of biolifting and have the greatest potential to find application as an isotopic proxy for P dynamics in soils.

Zheltozems of Russia: Micromorphology, clay minerals, and pedogenetic analysis .

Zheltozems (literally “yellow earths”) that can be classified as Acrisols, Alisols, or Ultisols, occupy very small areas in Russia; they are strongly modified by human activities. The unchanged profiles are preserved only locally, in particular, in the Sochi arboretum. When compiling the soil map of the arboretum, different Zheltozems were described on gentle and moderately steep slopes and diverse parent materials: calcareous claystone and its heavy-textured derivates. The micromorphology of three characteristic Zheltozem profiles developed on these different parent materials was also studied. The features that they have in common are the following: in all profiles, a specific heavy-textured Bw, or BM ‘metamorphic’ horizon was identified with a certain set of micromorphological properties: a massive microstructure with fine planes merging into deformed biogenic pores, a monic groundmass with few silt grains that are sometimes oriented, and impregnative iron-oxides pedofeatures. The b-fabric was defined as stipple speckled, poro- and granostriated, locally (mono)striated ressembling stress coatings. There are almost no clay coatings except for very few fine internal ones that are light yellow and homogeneous; clay and iron pseudomorphs (alteromorphs) occur over some skeleton grains. Many of these properties are related to the clay mineral composition. There are varying quantities of smectites and kaolinite-smectites, whereby the former increase with depth. The presence of expanding minerals is known to contribute to the disintegration of coatings. Remnants of these are observed in typic iron-manganic nodules. In terms of WRB, this horizon is an intergrade between cambic and argic, which is not accounted for in soil diagnostics. As three different Zheltozems are studied in the same area, the following genesis of this specific intergrade can be given. The saprolite in one of the profiles is composed of fragments of weathered calcareous argillites (subangular) and sandstones (angular) separated by planes with infillings. The micromass in the argillites is locally depleted of carbonates; some fragments have rusty-black iron-manganic intercalations, external clay coatings and iron quasicoatings. The infillings contain fine carbonate nodules and fragments of clay coatings. The sequence of soils studied enabled us to identify the pedoplasmation phenomena, as described by Stoops and Schaefer (2010). This process starts with the decarbonatization, fragmentation and ferrugination of rock fragments, which are gradually assimilated by the groundmass, so that only a trend to linear arrangement of grains is preserved. The pedoplasmation starts in the saprolite of in situ argillite, next follows a transformation of the lithogenic fabric into a pedogenic one with the development of a Bw horizon. These phenomena are more obvious in the profile on the oldest parent material – clayey colluvium. The low porosity and dense fabric of the Bw horizon hinder the removal of carbonates from the underlying layers (saprolite), and this may be a reason for the incompatibility between abundant rainfall inherent to the wet subtropical climate in Sochi region and the high position of the line of effervescence with hydrochloric acid in Zheltozems on calcareous argillite.

Soil Aggregate Stability in Different Soil Orders Quantified by Low Dispersive Ultrasonic Energy Levels

Ultrasonic dispersion of soil aggregates in water-based solutions is commonly used in soil science, because it is possible to quantify the amount of energy applied to the solutions. However, currently available instrumentation does not provide precisely controlled low ultrasonic energy; thus, the study of weakly aggregated soils is still a challenge. The aim of this study was to apply amplitude controlled, low energy ultrasonic dispersion to study macroaggregate breakdown in soil orders with wide range of stabilities and formed on diverse parent materials: alluvial calcareous sediments (Entisol), volcanic ash and basalt (Andisol), serpentinite (Alfisol), schist (Ultisol), and granite (Inceptisol). Aggregates were exposed to increasing ultrasonic energy levels in six steps from 0 to 40 J mL−1, and the resulting macro- and microaggregate masses were measured. Subsequently, the aggregate distribution was correlated with various physicochemical properties of the 250- to 1000-µm macroaggregates. The study showed that aggregate breakdown at low energy levels was greatest in the Andisol and the Entisol, followed by the Alfisol, Ultisol, and Inceptisol. Stability of macroaggregates was influenced by particle-size distribution, the amounts of exchangeable Mn (influenced mean weight diameter [MWD] positively) and exchangeable Mg (influenced MWD negatively). In contrast, stable microaggregates in the range of 63- to 250-µm were positively correlated with oxalate extractable Fe and Al as well as with soil organic matter (SOM) content. The results demonstrate that aggregate breakdown is strongly depending on the amount of energy applied, as well as of soil properties, which influence defined aggregate-size classes differently.

SEM image analysis for characterization of sand grains in Thai paddy soils

This study presents a detailed characterization of sand grains in 34 samples of Thai paddy soils (mostly Alfisols and Ultisols) that have formed from diverse parent materials. Computer analysis of SEM images of thin sections provided a novel and reliable method to analyse the size and shape of quartz grains using the software ImageJ 1.34S. Sand grain size expressed as the feret value showed a log normal distribution for 16 samples whereas for the other samples the distribution was positively skewed. A logit transformation of grain circularity values generated a normal distribution for 26 samples and eight samples had bimodal distributions. These granulometric data indicate the diversity of the soil parent materials and the observed soil layers represent discrete sedimentary events with materials of different origins or different depositional energies. Pedogenesis including pedoturbation has not disrupted these sedimentary layers. Some sand grains consist of gold, brass, copper, ilmenite, zircon, magnetite, barite or monazite. The diversity of these grains reflects the complex geology of the catchments providing the sediments and some anthropogenic materials may have been incorporated into the soils.

Phosphate sorption and desorption by Thai upland soils

Phosphate (P) sorption and desorption characteristics have been investigated for sixty-two representative samples of the major Thai upland agricultural soils which are Oxisols and Ultisols formed on diverse parent materials and under various climatic conditions. P sorption characteristics are well described by Langmuir and Freundlich equations. Values of Langmuir P sorption maximum ( X m) and b coefficient range from 47 to 1250 µg g − 1 soil and 0.5 to 30 mL µg − 1 , respectively and the Freundlich k varies between 12 and 1694 µg g − 1 and B coefficient 0.09 and 0.67. Soils derived from basalt have larger values of P sorption maximum than soils on other parent materials. Both P sorption maximum and Freundlich k are closely related to pH (NaF), SSA, total titanium, aluminum and iron, dithionite and oxalate extractable Fe and Al, and other soil properties that reflect specific surface area. Soil pH in NaF is highly effective in predicting the P sorption capacity of Thai upland soils explaining 79% of the variation in P sorption by these soils. P desorption curves for adsorbed P are well described by the Freundlich equation. The Freundlich k d coefficient for P desorption is highly, linearly related to the Freundlich k coefficient of P sorption indicating that the above soil factors that contribute to P sorption similarly affect P desorption.

Relationship between soil properties, crop management, plant growth and vigour, nematode occurrence and root damage in East African Highland banana-cropping systems: a case study in Rwanda

Abstract Parasitic nematodes are widespread in Musa cropping systems in African lowlands where they are known to limit crop production. However, their distribution is very poorly known in the large parts of the East African Highland banana ecology. We carried out a survey in 188 fields in Rwanda to assess and understand nematode occurrence and damage under a wide range of agroecological conditions. Altitude varied from 900 to 1800 m above sea level and soil types were distinctly different in the five eco-regions sampled and derived from diverse parent materials; i.e., Ruhengeri (Andosol), Gitarama-Butare (Acrisol), Kibungo (Nitisol), Gashonga (Ferralsol) and Bugarama (Fluvisol and Vertisol). Crop management practices, root health parameters and nematode infection in roots were recorded for a single East African highland banana cultivar (Intuntu, AAA-EA). Plant-parasitic nematodes from five genera were identified: Pratylenchus goodeyi, Helicotylenchus multicinctus, Meloidogyne spp., Radopholus similis and Hoplolaimus pararobustus. Pratylenchus goodeyi was the dominant species in all eco-regions except in Bugarama (lowland). Only the presence of P. goodeyi significantly correlated with root necroses. Altitude was strongly correlated with root densities of P. goodeyi and R. similis. A possible negative impact by P. goodeyi on banana yields was masked by the fact that nematode populations were positively correlated with high plant density and/or mulching practices, which led to relatively high plant vigour irrespective of soil type. Therefore, controlled field experiments will be needed to assess whether root necrosis caused by P. goodeyi at high altitude (&gt;1400 m) actually has a detrimental impact on banana yields, similar to that observed for root-lesion nematodes at lower altitudes.

Relationships between concentrations of trace metals in wheat grains and soil

In order to reduce the amount of trace metals such as cadmium in human food, it is useful to predict the trace metal composition of cereal grains from well-chosen topsoil variables. Statistical relationships between soil properties and metal concentration in plant organs have already been studied. However, such studies involved only a few common soil properties such as pH, organic carbon content and cation exchange capacity. Here, we compared metal contents in grain and in topsoil samples. 198 samples of grains of winter wheat were collected from paired topsoil and crop surveys in the northern half of France. The soils belong to 18 contrasting pedogeological families. Grain and topsoil samples were analysed for Cd, Cr, Cu, Ni, Pb, Zn, Fe, Mg and Mn. For soil samples, three pools of metal were determined: total concentration by HF digestion, and two available pools by partial extraction using either diethylenetriamine pentaacetic acid (DTPA) or NH4NO3. Canonical correlation analysis including multiple linear regression was used to study relationships between soil and grain data. Our findings show the occurrence of six significant and independent relations between the topsoil variables and the grain variables. The adjustment quality of those relations is measured by six coefficients equivalent to individual determination coefficients. The maximum coefficient of 0.79 is higher than any individual ones. Our findings show in particular an excellent regression model for grain Cd with a small number of topsoil variables, thus allowing an accurate prediction for winter wheat grains. Practically, farmers can use the prediction model to increase soil pH and by growing a less metal-accumulating cultivar upon detection of a threat. The strengths of our study are the following: (1) we studied a very large number of sites, including soils with very diverse parent materials, soil-forming processes and geochemical properties; (2) we measured and tested a large number of variables, including in particular available metal fractions; and (3) we applied unusual statistical methods such as canonical correlation analysis.

Morphological characteristics and classification of soils derived from diverse parent Materials in Central Cross River State, Nigeria

Variation in soil characteristics is usually a reflection of the difference in materials from which the soil was formed. This study sought to investigate the characteristics of soils formed on different parent materials with a view to classifying them. This study was carried out in selected soils derived from three major types of parent materials in central Cross River State, South Eastern Nigeria. A total of six (6) pedons were excavated, two (2) pedons in each of the identified parent materials. The parent materials were Sandstone-shale-siltstone intercalations. Basement complex and Basalt. The study indicated that soils derived from sandstone-shale-siltstone materials are characterized by ochric sandy loam and loamy sand epipedons with moderate medium sub-angular blocky structures. These soils are also light coloured with dominant hues of 7.5YR with hard to slightly hard and hard to very hard dry consistence at the surface and sub-soil respectively. Soils of basement complex are characterized by the possession of loamy sand epipedons with weak medium crumb and sub-angular blocky structures having predominantly dull yellowish brown and bright yellowish brown colours at the surface and sub-soils. The dry consistences of the surface soils are slightly hard while the sub-soils are hard to very hard. The Morphology of basaltic soils is characterized by sandy loam to clayed texture with strong medium to moderate medium sub-angular block structures. These soils are deep in effective depth and dark reddish brown in colour. Its dry consistence is usually hard to very hard to very hard. Soils of sandstone – shale-siltstone and basement complex origin are classified as Topic Tropustalfs while those of basalt origin are classified Topic Tropustults. Proper fertilization and irrigation programmes based on their inherent characteristics will make these soils more productive and enhance their potentials for sustainable agricultural use Keywords: Parent materials, Soil Morphology and sustainability Global Journal of Pure and Applied Sciences Vol. 14 (3) 2008: pp. 271-278

Biochemical properties of vineyard soils in Galicia, Spain

In the present study we investigated changes in soil biochemical activity in vineyard soils. With this aim, soil samples (0-10 cm) from 15 vineyard soils developed on diverse parent materials were collected during winter. All soil samples were analysed for a large number of both general and specific biochemical properties. The values of all of the biochemical parameters analysed were extremely low, between 3 and 39% of the usual values obtained for native Galician soils under climax vegetation. To estimate the level of biochemical quality of vineyard soils, while avoiding the problem of comparing soils with totally different organic matter contents, a biochemical equilibrium equation was used. The results showed that vineyard soils are highly degraded soils, for which in the most extreme cases, the value of the biochemical equilibrium index was 13%, i.e. almost 8 times lower that in high quality soils such as climax soils.

Properties of kaolins in red Oxisols and red Ultisols in Thailand

Purified samples of kaolin group minerals [kaolins] from red Oxisols and red Ultisols from 14 sites on diverse parent materials and under various climatic conditions in Thailand were characterized using analytical transmission electron microscopy, X-ray powder diffraction and chemical analysis. The kaolins show a variety of crystal morphologies including euhedral hexagonal to subhedral platy crystals, tubes and partly rolled tubes. Tubes and partly rolled tubes occur in soils under both udic and ustic moisture regimes (i.e. Rhodic Kandiudox, Typic Kandiudox, Typic Kandiudults, Rhodic Kandiustox). The lowest kaolin HB crystallinity index (3.3–5.3) and smallest size (9–11 nm) are for kaolins consisting of anhedral plates, tubes and partly rolled tubes in a soil on basalt under very high rainfall. This kaolin has the highest specific surface area (SSA) (35–64 m 2 g − 1 ), cation exchange capacity (CEC) (16–23 cmol kg − 1 ) and Fe 2O 3 content (1.99–3.62%). The trend of increasing kaolin crystal size with associated decreasing CEC and SSA in these soils is in the sequence red Oxisols on limestone under ustic moisture regime < red Ultisols on old alluvium < red Oxisols on basalt under ustic moisture regime < red Oxisols on limestone under udic moisture regime < red Oxisols on limestone under udic moisture regime < red Ultisols on sedimentary rock under udic moisture regime.

Properties of iron oxides in red Oxisols and red Ultisols as affected by rainfall and soil parent material

Tropical soils developed from various parent materials and under various rainfalls were analysed to identify whether these environmental factors influence the properties of the iron oxides. Iron contents of the soils range from 5 to 134 g/kg, with hematite and goethite being the major secondary iron minerals. Hematite is the dominant iron oxide in all soils developed on limestone irrespective of rainfall, whereas for other parent materials the relative abundance of goethite tends to increase with rainfall. Aluminum substitution in goethite and hematite ranges from 13 to 21 mol% and 7 to 15 mol%, respectively. The mole% Al substitution in hematite is about half the level for goethite in the same soil. Crystal size estimated from X-ray diffraction line broadening ranges from 12 to 47 nm for goethite and from 15 to 44 nm for hematite. Similar sizes were obtained by electron microscopy. The properties of the iron oxides did not vary systematically with parent material or rainfall and are similar to those described by other workers for red tropical soils on diverse parent materials.