Spatial variability of soil properties

Spatial variability is one of the most significant characteristics of soil properties, even within homogeneous layers. The physical description of this spatial variation is unclear, due to the highly expensive sampling, uncontrollable measurement errors, and modeling uncertainty. While the deterministic approach failed to present a reasonable quantification for the spatial variability of soil properties, the probabilistic approach has been utilized to assess and quantify the effects of soil spatial variability on the behavior of some typical soil-structure systems.
This study investigates the effect of spatial variability of soil properties (mass density γs, coefficient of friction tanδ, angle of internal friction (φ), and wall mass density γc, on the factors of safety against sliding (Fs), and overturning (Fo), as well as the maximum bending moment (M) of cantilever retaining walls.
For risk assessment, soil properties are described using appropriate probabilistic models. Deterministic analysis combined with Monte Carlo Simulation (MCS) is employed to analyze both spatially fully correlated and spatially uncorrelated soil profiles.
A FORTRAN program is developed to: (1) generate random variables with both Gauassian and non-Gauassian probability density functions (PDF); (2) simulate possible probability distributions for distinct soil properties; (3) perform repetitive analysis for each set of variable PDFs to generate the population of Fs, Fo, and M; and (4) calculate the statistical parameters of Fs, Fo, and M. The program is then applied to conduct an extensive parametric study.
This parametric study is performed to quantify and assess the effects of model uncertainty and the effect of spatial heterogeneity of soil properties, utilizing two different soil profiles: (1) spatially fully correlated soil profile; and (2) spatially uncorrelated soil profile. 
The numerical results show that the effects of spatial variability and uncertainty of input variables on wall safety vary from one variable to the other. Consequently, considerable care should be directed to those variables that have the greatest effects. For typical degrees of uncertainty, it is found that the structural risk is highest when the PDF of tanδ and φ is normal (Gauassian), or has an upper triangular shape (non-Gauassian). In addition, it is found that accounting for soil spatial variability in design of retaining walls leads to more economic designs, as it produces smaller probabilities of failure. In other word, negligence of the spatial variability in the design of retaining wall is conservative.

Strong ground motions can trigger soil liquefaction that will alter the propagating signal and induce ground failure. Important damage in structures and lifelines has been evidenced after recent earthquakes such as Christchurch, New Zealand and Tohoku, Japanin 2011. Accurate prediction of the structures’ seismic risk requires a careful modeling of the nonlinear behavior of soil-structure interaction (SSI) systems. In general, seismic risk analysisis described as the convolution between the natural hazard and the vulnerability of the system. This thesis arises as a contribution to the numerical modeling of liquefaction evaluation and mitigation.For this purpose, the finite element method (FEM) in time domain is used as numerical tool. The main numerical model consists of are inforced concrete building with a shallow rigid foundation standing on saturated cohesionless soil. As the initial step on the seismic risk analysis, the first part of the thesis is consecrated to the characteriz...

En años recientes se ha incrementado el interes y la producción ecológica de cerdos en sistemas al aire libre, considerados por varios autores como una alternativa a los grandes sistemas confinados, por ser respetuosos del comportamiento animal y ambientalmente amigables.  Con el objetivo de estudiar impactos sobre el suelo de un sistema de cerdos en pastoreo luego de 12 años, se muestreó 6 parcelas de 1500 m2 y un área testigo (sin cerdos). El suelo es un Brunosol y las cerdas se manejan en con cargas promedio de 6 cerdas ha-1 año-1, con dieta a base de ración y acceso permanente a pasturas. El sistema produjo modificaciones en propiedades físicas, químicas y biológicas del suelo, generando heterogeneidad espacial en zonas diferenciadas de manejo. La zona de servicio concentró los mayores impactos y la de pastoreo (75% del área) los menores. El sistema ocasionó compactación del suelo, superando los 2 MPa de RP solo en áreas reducidas de la zona de servicio, que fue la más compactada. La MO se redujo de 4,7% en el suelo testigo a 3,9% en el suelo con cerdos en la capa superficial, disminuyendo también 17% en profundidad, explicado fundamentalmente por la disminución de la MONP y sin diferencias significativas entre las zonas de las parcelas. Se incrementó el contenido de P, NO3 y K fundamentalmente en el área de servicio, correlacionados con la conductividad eléctrica del suelo, la cual no llegó a valores problemáticos. El exceso de N fue escasamente acumulado en el suelo, incrementando el riesgo de contaminación de aguas. En la zona de pastoreo el pH disminuyó 0,4 unidades en relación al testigo (p<0,05), la cual no se diferenció significativamente con el área de servicio. Algunos impactos se extendieron en forma significativa (p<0,05) a la capa de 15-30 cm (RP, COS, P, NH4 y CE). No se observó problemas de acumulación de metales pesados (Zn y Cu). Producir cerdos a campo puede ser una alternativa de monores costos de producción a sistemas confinados, pero los resultados sugieren que es una actividad con potencial de generar problemas ambientales por inadecuadas prácticas de manejo.

This study presents an innovative procedure to derive the ultimate load capacity of a pile system by considering the natural (intrinsic) variability of a tropical soil. The tropical soil has high aluminum and iron content due to processes of lixiviation of the upper soil layers. As a consequence, this soil has a porous cemented structure, high void ratio, high permeability, and high variability of the geotechnical parameters in its depth. Soil layers are experimentally characterized via standard characterization, a triaxial test, standard penetration test, and flat dilatometer tests. Also, the load test of the standard groups (PG) and pile plus pile-cap (PC), which had self-drilling piles, were performed at real scale. Afterwards, simulations using a three-dimensional finite-element method (3D FEM) considering variations in soil parameters were performed for a hypothetical piles-plus-pile cap system under vertical loading using the random finite-element method. Mean parameters were verified through laboratory and field tests. Results from the load test simulations were compared with real-scale tests conducted in this study. The relative importance of variability of several geomechanical parameters was analyzed in terms of their effects on the contribution of the pile cap to the ultimate bearing capacity of the full system and found to be 18%; the minimum contribution is 2% of the total load. Finally, it is shown that reasonable savings in construction costs accompanied by a modest reduction in the safety factor (FS = 1.8) may occur when the variability of parameters is taken into account.

The objective of this study was to determine spatial variability of particle size distribution, organic matter and lime contents, pH and plant-available P content of soils located in the Experimental Station of Eastern Anatolia Agricultural Research Institution. The research area, about 100 ha, was divided into 100 m interval grids in the north to south and east to west directions, and 68 soil samples were collected from 0-20 cm depth at the corner of each grid. Isotropic-exponential semivariograms were fitted to explain spatial variability of clay and silt contents. Sand content and
organic matter were explained with isotropic Gaussian emivariograms and lime and pH with an isotropic spherical semivariogram. Block Kriging analysis, an advanced interpolation technique, was performed to prepare spatial distribution maps. The distribution patterns indicated that, clay content
soils closer to the creek bed was the lowest within the research field, but sand content was higher closer to the creek bed. However, silt content showed unstable distribution patterns within study area. Distribution patterns of organic matter showed good agreement with crop type. While organic matter of soil was higher in cereal planted areas and lower in row-crop planted areas. The maximum values of soil lime content and soil pH were obtained at the areas away from the creek bed.

Soil series are designed to be highly homogenous to the extent that they could be managed as a single unit, especially when precision agriculture is not practised. A study was carried out in Papalanto in Ogun State to evaluate the variation between some contiguous soils series formed on shale parent material in South Western Nigeria. A detailed soil survey was carried out on a 100 m by 100 m rigid grid transects for identification, characterization and classification of the soil series. Soil samples were randomly and representatively collected at 0 – 15 cm (surface) and 15 – 30 cm (subsurface) for each of the delineated series. Data collected on the various soil series
were compared in randomized complete block design (RCBD) using analysis of covariance (ANCOVA) with subsurface soil as the dependent and surface soil as independent variables. The soil series classified were Abesse, Lapeleke, Yewa, Ogun and
Onikoko occupying 50%, 10%, 16%, 4% and 20%, respectively, of the study area. The sand contents of Abesse, Lapeleke and Onikoko series (ranged from 547.1– 612.7 g kg-1) were not significantly different from each other, and Yewa series was not significantly different from Onikoko. Similar trend in variability was observed in the clay content, which explains their similarity in the morphological classification. The properties of Abesse series including pH, available phosphorus, total nitrogen, organic carbon, exchangeable bases, ECEC, extractable manganese, zinc and copper were higher than other soil series with the exception of exchangeable acidity (0.3 cmol kg-1) and extractable iron (124.9 mg kg-1). The pH (H2O and KCl) of Onikoko soil series (5.4 and 4.9, respectively) were significantly different from those of Abesse series (6.0 and 5.3, respectively). Ogun State soil series was least in the majority of properties with the exception of ECEC (23.6 cmol kg-1), potassium (1.4 cmol kg-1) and soil organic carbon content (31.9 g kg-1). The properties of soil series studied were significantly different from each other and could be managed differently with the exception of Abesse and Onikoko series that could be managed similarly.

This article presents the steps taken to ensure the consistency and usability of the geographic information system of soil resources of Romania SIGSTAR-200 within INSPIRE, the Infrastructure for Spatial Information of the European Community. At present, SIGSTAR-200 contains tens of thousands of polygons characterized by three attributes collected from legacy paper maps, namely (i) soil mapping unit (SMU), including soil association, (ii) topsoil texture class and (iii) skeleton class, all defined as stated by the national methodologies. In addition, each soil is characterized concerning the risk of land degradation (by water erosion, wind erosion, salinization, alkalization, gleyzation and waterlogging) through attributes inferred by expert system rules built on pedogenesis. To achieve the compatibility and usability within INSPIRE, SIGSTAR-200 has been transformed in accordance with the common Implementing Rules in force. To this end, first, the SMUs have been correlated at the dominant soil type level with the international soil classification system World Reference Base of Soil Resources (WRB) to ensure the semantic interoperability. Second, the SMUs, modeled as INSPIRE feature type SoilBody, have been populated with new attributes. This step was performed for SIGSTAR-200 dataset in three coordinate reference systems (CRSs): EPSG:3844 (CRS of Romania), EPSG:3035 and EPSG: 4258 (the last two CRSs being required or recommended by INSPIRE). Finally, the data transformed in INSPIRE-compliant GML have been checked by the INSPIRE Validator (Executable Test Framework), passing all the tests currently available for soil datasets, i.e., regarding (i) data consistency, (ii) INSPIRE GML application schemas, (iii) information accessibility, and (iv) reference systems. The next steps of the work, synchronized with the availability of the Executable Test Suites for the themes defined in Annex III of the Directive, aim to fully validate SIGSTAR-200 GML and to conclude its first integration into INSPIRE (Accession Number: WOS: 000526176700012).

To investigate spatial variability in topsoil (0-20 cm) pH, available phosphorus (P), potassium (K), total nitrogen (N), and soil organic matter (SOM) of small fields ($2 ha), and to determine the impact of soil heterogeneity on the spatial variability of crop yield two fields were cropped with spring oats and one with winter wheat under humid-temperate conditions. In the two oat fields, some of the measured soil properties (P, K) and the grain yield varied considerably, and strong spatial trends were recorded for most of the soil traits. In the third field, soil properties showed only a moderate spatial variation, and no spatial trends were found. The spatial distribution of SOM and total N in the topsoil had some influence on the spatial pattern of the oat grain yield in the field of Gr€ anichen; however, spatial relationships between soil chemical properties and grain yield were rather weak in our study.

Since the change of land use accrued in the Iran, especially in northern Iran, this
research aims tocompare the spatial variability of soil properties in three adjacent land uses
including cultivated by wheat lands, grazing lands and forest Lands covered by juniperus sp,
fagus orientalis, quercus castanifolia, and acer velotinum species in kiasar region, Mazandaran
Province, northern Iran. Some of soil features, i.e. pH, CaCO3, total nitrogen (TN), soil organic
carbon (SOC), electric conductivity (EC), percentage of silt, clay and sand contents and saturation
moisture content(SM) were measured at a grid with 20 m sampling distance on the top soil (0 – 30
cm depth). Accordingly, total of 147samples were taken from 49 soil sites. The normality of data
was examined by the tests of normality. Then, data were analyzed by using of geostatistics
approach. The results showed that spatial distribution of many soil properties could be well
described by spherical model in the forest and exponential model in the cultivated and grazing
lands. Spatial dependences were the highest for SOC, EC and the lowest for silt, (SOC and silt) in
the forest method and grazing lands, respectively. Deforestation and conversion to cultivated and
grazing lands decreased spatial dependence of soil properties.

Wet soils are widespread in Southern Nigeria and are available for the expansion of agricultural production but their properties are not well known. This study was conducted to investigate microaggregate stability of soils on different parent materials in Akwa Ibom and Cross River States in Southern Nigeria. Four tests of microaggregate stability were used, namely; water dispersible clay (WDC), clay dispersion ratio (CDR), dispersion ratio (DR), clay flocculation index (CFI), aggregated silt+clay (ASC) and water stable aggregates (WSA<0.25 mm). The results show that WDC was lower under coastal plain sands soil in Obio Akpa than under the sandstone and shale parent material in Akai Effiwatt. However, while CDR and DR were higher in Obio Akpa than in Akai Effiwatt soils, CFI and ASC were higher in the latter than in the former. The results further show that CDR was significantly related to CFI (r=-0.99, P<0.01) and DR significantly related to ASC (r=-0.89, P=0.001) in Obio Akpa. Under sandstone and shale parent material, WDC was significantly related to CDR (r=0.86, P<0.01) and CFI (r=-0.86, P<0.01), CDR was significantly related to CFI (r=-0.99, P=0.001) and DR to ASC (r=-0.84, P<0.01). Among the six (6) tests of stability, DR and WSA<0.25 mm had the lowest CV
values of 18.4% under coastal sand and 12.5% under sandstone and shale, respectively, and can be used routinely for characterizing the structural stability of the wet soils on the
respective parent materials, and in similar ecologies.

Understanding topography or slopes, identifying physical and chemical properties of soils improves greatly informed management decisions for agricultural productivity. The study on variation of some physical and chemical properties of soils as affected by slope positions was aimed at providing critical fertility status of the soils. Farmers have complained of reduced output from their farm lands due to leaching activities and erosion hazards. Slope positions were delineated using the Geographic Information System (GIS) and 3 different slope positions were identified (SP1, SP2 and SP3), and each slope position was recognized as a unit. Three (3) profile pits were dug in each unit located at Kugon (SP3), Timdore (SP2) and Sammeri (SP1) respectively. Soil samples were collected in each identified soil horizon of the pits and soil samples were collected for Original Research Article Gisilanbe et al.; AJSSPN, 2(3): 1-13, 2017; Article no.AJSSPN.39047 2 laboratory analysis of some physical and chemical soil properties and One-way analysis of variance was carried out using GraphPad Prism (2007) software, version 5.0 at p<0.05. Soils were slightly acidic to neutral and predominantly sandy in nature (81.00%). The study revealed that slope position influenced water holding capacity and water retention in and were significantly different. Soil chemical properties were not significantly affected by slope positions. The soils were low in nitrogen (0-0.15%), organic carbon (<1%), while AV-P were generally rated medium (10-20), high Ca 2+ (>5) at the Bt horizon, Mg 2+ (>1) and %BS were rated medium to high (50-80, >80) regardless of slope position and are considered fertile with high potential to support agriculture. Good and improved management practices like use of organic material and integrated nutrient management (INM) practice will improve the soil texture and structure; reduce leaching activities and erosion hazards in the area.

Several attempts have been made to devise alternate plastic limit (PL) determination methods, targeting higher degrees of repeatability and reproducibility. Among these, empirical-type correlations linking the plasticity index (PI) to the flow index (FI) - the slope magnitude of the flow curve - seem to be gaining increased attention, particularly for the fall-cone (FC) approach, and hence demand further examination. To better understand the true potentials and limitations of this emerging practice for soil plasticity determination, this study presents a critical statistical appraisal of FI-based correlations - using a large and diverse database of 230 FC tests (for the 80 g-30°cone) - in estimating the PI (and hence the PL). It is demonstrated that the so-called "strong" correlation between the PI and FI reported in some literature, favoring the use of FI as a PI estimator, is an overlooked "statistical pitfall" originating from an over-reliance on the coefficient of determination (R2) statistic. Employing appropriate error-related statistics, it is shown that the PI predictions made by FI-based correlations are associated with high average errors of 22-33 %. Hence, such correlations, at best, can only provide a rough approximation of the actual PI (and hence PL). An attempt is also made to assess the validity of FI-based correlations in the context of soil classification using the Casagrande-style plasticity chart. The agreement level between the conventional classification approach and that performed using PI deduced from FI-based correlations was 75-80 %. This analysis, however, did not account for errors in the rolling-thread plastic limit data, maintaining a strong possibility that FI-based correlations may be suitable for routine soil classification purposes.

The success of any software product line development project is closely tied to its domain variability management. Whereas a lot of effort has been put into functional variability management by the SPL community, non-functional variability is considered implicit. The result has been dissatisfaction among clients due to resultant poor quality systems. This work presents an integrated requirement specification template for quality and functional requirements at software product line variation points. The implementation of this approach at the analytical description phase increases the visibility of quality requirements obliging developers to implement them. The approach proposes the use of decision tree classification techniques to support the weaving of functional quality attributes at respective variation points. This work, therefore, promotes software product line variability management objectives by proposing new functional quality artifacts during requirements specification phase. The approach is illustrated with an exemplar mobile phone family data storage requirements case study.

Characterizing spatial soil heterogeneity within
orchards may provide an approach for precise,
more sustainable production processes. In predominantly
sandy soil, which was formed by glacial and
post-glacial deposits, generative growth of plum
trees (Prunus domestica ‘Tophit plus’, n=156) were
closely analyzed (􀏐lower set, fruit set, fruit drop,
fruit size, fruit pigments, and yield), and classi􀏐ied
according to the apparent electrical conductivity
(ECa) of the soil in three depths (topsoil, root zone,
subsoil). The soil ECa showed small scale variability
between 1.3 mS m-1 and 76.7 mS m-1 with stable
pattern for two years (R=0.88). The ECa in different
depths corresponded to compaction pro􀏐ile and water
content of the sandy soil. The ECa in the root zone
correlated to tree growth. However, the ECa of topsoil
and elevation (slope = 3.15°) of the terrain had a
similar or enhanced impact. The ECa in topsoil and
elevation were correlated with fruit set at r=0.17
(p=0.011) and r=-0.45 (p=0.133), and fruit size at
r=0.06 (p<0.001) and r=0.05 (p<0.001) respectively.
Such 􀏐indings are particularly interesting for orchards
showing elevation gradient or soil compaction
from mechanical weed control

Understanding the spatial variability of soil properties is useful to tailor site-specific agricultural inputs to enhance crop production on a sustainable basis. This study was aimed to assess and map the spatial patterns of soil acidity and nutrients using geostatistical methods and support site-specific lime and fertilizer recommendations in Bedele district, Southwestern Ethiopia. Soil samples were collected from agricultural land at a depth of 20 cm using grid sampling technique. The semivariogram analysis was performed for accurate spatial prediction and the kriging technique was used for interpolation of soil parameters. Soil pH varied between 4.5 and 6.8. Soil organic carbon (OC) content ranged from 0.3 to 5.6% and the mean soil OC density was 0.81 kg m−2. Available phosphorus (AvP) ranged from 0.8 to 38.6 mg kg−1 and nearly 80.23% of the soils exhibited very low to low AvP that could be due to fixation by strong acidity. Soils of the study area exhibited very high exchangeabl...

Remote Sensing(RS) and Geographical Information System (GIS) has become an effective tool in delineation of drainage pattern and water resources management and its planning.In the present study, morphometric analysis of the Vrishabhavathi river basin has been carried by using earth observation data and GIS techniques. The morphometric analysis was performed using ArcGIS to understand the nature, landscape development and hydrologic responses of Vrishabhavathi watershed. The drainage network shows that the terrain exhibits dendritic drainage pattern.The CARTOSAT and LISS(III) (SRTM) data is used for the morphometric analysis of the watershed to derive linear, relief, and aerial aspects.Spatial analysis is performed using ENVI for change detection studies in the basin to understand the effect of urbanization. Strahler's stream ordering techniques and analysis were followed for advanced analysis.From the analysis, it can be concluded that remote sensing techniques and GIS tools prove to be a competent tool in morphometric analysis. These studies are very useful for sustainable urban planning and also for land, water, and soil resource management in the watershed area.

The research team conducted pots experiment in a Silty clay loam soil to investigate the effect of inoculation with Mycorrhizae (MH), Vermicompost fertilizer (VRF) and chemical fertilization (CF) on the growth and yield of soybean (Glycine max) and some soil properties after cultivation, The team used complete randomized design CRD experimental system of three replications. Experimental treatments were; control (zero addition) (T1), the addition of CF alone as a complete recommendation (100 N, 160 P2O5, 80 K2O kg.ha-1) (T2), addition of MH fungi (10 g.pot-1) (T3), MH + half of the CF recommendation (T4), VRF (2 tons.ha-1) (T5), VRF + half of the CF recommendation (T6), VRF + MH (4 ton.donm-1) (T7), and finally MH + VRF + half CF recommendation (T8), in addition to interactions among these parameters. The seeds of the soybean were inoculated with specialized rhizobia (RHZ). Then, they were implanted on May 5, 2019. After maturity of the pods, they were harvested on 1st September, 201...

Three-dimensional (3D) printing in soil science is relatively rare but offers promising directions for research. Having 3D-printed soil samples will help academics and researchers conduct experiments in a reproducible and participatory research network and gain a better understanding of the studied soil parameters. One of the most important challenges in utilizing 3D printing techniques for soil modeling is the manufacturing of a soil structure. Until now, the most widespread method for printing porous soil structures is based on scanning a real sample via X-ray tomography. The aim of this paper is to design a porous soil structure based on mathematical models rather than on samples themselves. This can allow soil scientists to design and parameterize their samples according to their desired experiments. An open-source toolchain is developed using a Lua script, in the IceSL slicer, with graphical user interface to enable researchers to create and configure their digital soil models,...

The objective of this study was to determine spatial variability of particle size distribution, organic matter and lime contents, pH and plant-available P content of soils located in the Experimental Station of Eastern Anatolia Agricultural Research Institution. The research area, about 100 ha, was divided into 100 m interval grids in the north to south and east to west directions, and 68 soil samples were collected from 0-20 cm depth at the corner of each grid. Isotropic-exponential semivariograms were fitted to explain spatial variability of clay and silt contents. Sand content and organic matter were explained with isotropic Gaussian semivariograms and lime and pH with an isotropic spherical semivariogram. Block Kriging analysis, an advanced interpolation technique, was performed to prepare spatial distribution maps. The distribution patterns indicated that, clay content soils closer to the creek bed was the lowest within the research field, but sand content was higher closer to ...

The aim of this research was to assess changes in the physical and chemical properties of soil and the rate of erosion under traditional land use and during the natural vegetation succession following land abandonment, in a marginal area of Portugal. A chronosequence was used, which included soils cultivated with cereal crops (the traditional land use in the territory), the typical stages in vegetation succession following land abandonment (herbaceous, shrub and wood), and native forest (used as a reference ecosystem).The results indicated that the differences in both soil properties and soil erosion were related to land management and the different stages in plant succession, highlighting that continuous cropping is primarily responsible for depleting soil nutrients and intensifying the degradation processes.

The aim of this work was to evaluate prediction maps created with interpolation for five common topsoil properties, namely organic matter, total CaCO3, electric conductivity, Fe content, and clay content in a Mediterranean agricultural system. Knowledge about spatial variance of soil properties is of significant importance when implementing "good farming rules" towards sustainable rural de- velopment. A 25 ha block of fields cultivated with grape vines and olive trees in the island of Crete was targeted as a study site. 106 topsoil samples were collected on a 50 × 50 m2 grid and then analysed in the laboratory. Three well-known spatial interpolation techniques, namely Ordinary Kriging (OK), Inverse Distance Weighting (IDW), and Radial Basis Functions (RBF) were applied for generating the prediction maps, which then were assessed for their accuracy and effectiveness with a new, independent set of samples. This time the samples were collected randomly. The re- sults indicated that there was not a method clearly more accurate than the other methods for any of the tested properties. The Goodness of prediction (G) had positive values for Fe content and total CaCO3 for all interpolation techniques and positive values for Organic Matter only for IDW. Among G values, only the value for total CaCO3 was big enough for all techniques, indicating that only this specific property counted for mapping. It is believed that the topography, crop alteration and farming practices significantly affected the results in the specific landscape. Future research will focus on taking account of between-field variations that are due to different crops or farming practices, incorporating segmentation techniques on cadastral data and satellite imagery.

The significance of Saharan dust deposits for ecosystems has been demonstrated in several studies, showing its influence on pedogenesis and soil chemical and physical parameters by the addition of nutrient elements. This contribution is especially important for volcanic soils poor in plant-available phosphorous as those of the island of La Palma (Canary Islands, Spain). Thus, this study investigates the spatial distribution of Saharan dust on the island, and determines its influence on soil properties and thus on the ecosystem of the island. Since silt-sized quartz is not autochthonously formed on the island, it served as a reliable indicator for Saharan dust. Quartz was identified and quantified using X-ray diffractometry. The influence of Saharan dust additions on soil properties was assessed by texture analyses and analyses of plant-available phosphorous, an element strongly limiting plant-growth on the island due to its fixation in the structure of amorphous volcanic clay. A luff-lee-effect revealed significant influence on dust distribution, whereas small geomorphologic structures as hollows and mounds hardly influenced the dust distribution pattern. A positive correlation of quartz content with the proportion of the grain size fraction 0.5-10 µm demonstrates an influence on soil physical properties, apparently influencing available water capacity. Furthermore, our data suggest an increasing content of plant-available phosphorous with a rising amount of Saharan dust in the soils. Thus, the input of Saharan dust influences soil fertility of La Palma and is an important factor regarding the fragility of the La Palma ecosystems.

To provide spatial information on soil resources for sustainable land management in the Mt. Wakakusa Grassland of central-western Japan, we investigated the spatial variation and distribution of selected micronutrients, i.e., Mehlich 3 extractable Fe, Mn, Cu, and Zn (referred as M3-Fe, M3-Mn, M3-Cu, and M3-Zn, respectively), in surface soils (0-5 cm in depth) of the grassland. All micronutrients showed intermediate variability, with coefficients of variation ranging from 26.9 to 48.9%. The M3-Fe (144.0 ± 32.9 mg kg −1) and M3-Mn (204.8 ± 91.3 mg kg −1) contents were relatively high compared with the optimal level exhibited by M3-Cu (1.8 ± 0.5 mg kg −1) and the low level given by M3-Zn (7.8 ± 2.2 mg kg −1). The availability of these micronutrients, except for M3-Zn, showed more significant correlations with the soil mineral phase than with the soil pH and organic matter. Variogram analysis reveals a moderately weak spatial dependency [nugget-to-sill (N/S) ratio = 0.67] for the M3-Zn, while the other micronutrients (M3-Fe, M3-Mn, and M3-Cu) exhibit moderately strong to strong spatial dependencies (N/S ratio = 0.21-0.50). Interpolation maps created in this study demonstrate locations with toxic levels of M3-Fe and M3-Mn and those deficient in M3-Mn and M3-Cu in the study site. Based on these results, a site-specific soil management scheme is recommended in the Mt. Wakakusa Grassland.

Mt. Wakakusa in Central Japan is a semi-natural grassland which has been maintained by repeated application of prescribed burnings of vegetation for more than 500 years. We assessed the spatial variability of selected soil properties and constructed their distribution maps using a geostatistical method to provide spatial information on soil resource for sustainable land management in this grassland. All the examined soil properties showed intermediate (coefficient of variation [CV] = 10%-90%) or high (CV > 90%) variability, except for the soil pH (CV < 10%), suggesting that the precision soil management approach is recommendable in the study site. The variogram analysis revealed that all of the soil properties, except for the electrical conductivity with a very weak spatial dependency (nugget-to-sill [N/S] ratio > 0.75), showed a very strong or moderately strong spatial dependency (N/S ratio ≤ 0.50), which might occur under the strong influence of intrinsic factors such as the inherent soil quality. The soil maps constructed by the ordinary kriging method helped in understanding the distribution patterns of the examined soil properties and identifying specific locations with signs of degradation and pollution. These spatial distribution patterns should be considered when developing a sustainable soil management strategy in Mt. Wakakusa grassland.

Combined paddy and other field crops (OFC) fields are unique from other wetland or upland soils, because of seasonal alternation of wetting and drying conditions resulting anaerobic and aerobic conditions. Therefore, objective of this study was to assess spatio-temporal variation of soil properties in paddy fields under minor tanks with respect to OFC cultivation. Soil samples were collected at two soil depths from 24 locations covering the entire command area of the Bayawa Minor Irrigation Tank (MIT), Sri Lanka. Soil properties were analyzed and mapped using Arc GIS. Hardpan depth (HPD) was also determined by collecting undisturbed core samples at 0, 15, 25, 30, 45 and 60 cm depths from the same locations Statistical analysis was done to identify spatio-temporal variability of each property. Results revealed that, Bayawa command area showed low coefficient of variation (CV) for pH and bulk density, but high CV for saturated hydraulic conductivity (Ks). HPD was found to be varied in each section within the effective root zone. Overall, low Ks, high clay content, high field capacity, poor drainage and the presence of hardpan are major obstacles to introduce OFC. Therefore, introduction of site specific OFC by considering the variability of soil properties is very important for sustainability of the MIT system.

Keywords: Cropping intensity, drainage, hardpan, minor irrigation tanks, OFC

The objective of this study was to determine spatial variability of particle size distribution, organic matter and lime contents, pH and plant-available P content of soils located in the Experimental Station of Eastern Anatolia Agricultural Research Institution. The research area, about 100 ha, was divided into 100 m interval grids in the north to south and east to west directions, and 68 soil samples were collected from 0-20 cm depth at the corner of each grid. Isotropic-exponential semivariograms were fitted to explain spatial variability of clay and silt contents. Sand content and organic matter were explained with isotropic Gaussian semivariograms and lime and pH with an isotropic spherical semivariogram. Block Kriging analysis, an advanced interpolation technique, was performed to prepare spatial distribution maps. The distribution patterns indicated that, clay content soils closer to the creek bed was the lowest within the research field, but sand content was higher closer to ...

Spatial variability of soil materials has long been recognized as an important factor influencing the reliability of geo-structures. This study stochastically investigates the influence of spatial variability of shear strength on the stability of heterogeneous slopes, focusing on the auto-correlation function, auto-correlation distance and cross-correlation between soil parameters. The finite element method is merged with the random field theory to probabilistically evaluate factor of safety and probability of failure via Monte-Carlo simulations. The simulation procedure is explained in detail with suggestions on improving efficiency of the Monte-Carlo process. A simple procedure to create cross-correlation between random variables, which allows direct comparison of the influence of each strength variable, is discussed. The results show that the auto-correlation distance and cross-correlation can significantly influence slope stability, while the choice of auto-correlation function only has a minor effect. An equation relating the probability of failure with the auto-correlation distance is suggested in light of the analyses performed in this work and other results from the literature.

In precision Agriculture, geostatistical methods as a predictive tool have been extensively utilized. The approach estimates soil properties spatial variability and dependency. This study was carried out in Ovia north east Local Government Area of Edo State of Nigeria in order to map soil properties (Sand, Clay, pH, OC, P, N and CEC) and redict their spatial variability. Twenty-nine (29) soil samples were collected randomly from Typic Kandiudults soil type under three different land use, teak forest plantation, shrub, and arable farm. The soil samples were air-dried and passed through a 2 mm sieve before being analyzed for pH(CaCl2), SOC, Sand, Clay, Phosphorus, Nitrogen, and CEC. Generated data were statistically and geostatistically computed to explain the spatial variability of soil properties. The traditional method of soil analysis and interpretation are tedious, time-consuming with escalating budgets thus geostatical approach. Available phosphorus yielded large variability wit...

Evaluation of Slope stability is one of the day-today practices of geotechnical engineers. Nowadays, different methods are available to evaluate the stability of a particular slope. Despite the advances that have been made in site exploration, evaluating the stability of slopes remains a challenge. Recently, Ethiopia has been trying to construct a newly planned railway routes to connect the country&#39;s development centers and link with ports of neighboring countries. However, this newly planned railway routes will pass in the heart of highly fragile mountainous terrains and earthquake prone regions. Therefore, the prime objective of this paper is to investigate the stability of the railway embankment by using three different stochastic approaches (First Order Reliability Method, Point Estimate Method and Monte Carlo Simulation) with commercially available finite element and finite difference programs. Moreover, the seismic response of the railway Vol. 22 [2017], Bund. 01 52 embank...

The highly variable nature of weak rock in weathered sedimentary deposits poses significant challenges to open pit and underground mine design. Traditional probabilistic analysis fails to consider all potential mechanisms of instability that may influence slope stability. An approach with spatially variable strengths allows the natural variability of the shear strength properties within the rock mass to be simulated. This paper examines the congruence of geotechnical block modeling and spatial variability analysis to estimate the probability of failure of a highly variable weathered open pit slope in the Central African Copperbelt. The input parameters for the random spatial field simulations are estimated from variography of composited drill hole data and univariate statistics of a 3D block model of rock-mass shear strength. The Rocscience software Slide2 is used to perform the random field simulations and analysis. It is also demonstrated that the total variance can be reduced by the small-scale variability (nugget effect variance) for spatially averaged shear strengths. Typical rock-mass spatial parameters from other projects are summarized.

Legacy soil data have been produced over 70 years in nearly all countries of the world. Unfortunately, data, information and knowledge are still currently fragmented and at risk of getting lost if they remain in a paper format. To process this legacy data into consistent, spatially explicit and continuous global soil information, data are being rescued and compiled into databases. Thousands of soil survey reports and maps have been scanned and made available online. The soil profile data reported by these data sources have been captured and compiled into databases. The total number of soil profiles rescued in the selected countries is about 800,000. Currently, data for 117,000 profiles are compiled and harmonized according to GlobalSoilMap specifications in a world level database (WoSIS). The results presented at the country level are likely to be an underestimate. The majority of soil data is still not rescued and this effort should be pursued. The data have been used to produce soil property maps. We discuss the pro and cons of topdown and bottom-up approaches to produce such maps and we stress their complementarity. We give examples of success stories. The first global soil property maps using rescued data were produced by a top-down approach and were released at a limited resolution of 1 km in 2014, followed by an update at a resolution of 250 m in 2017. By the end of 2020, we aim to deliver the first worldwide product that fully meets the GlobalSoilMap specifications. Regardless of being national, continental and/or global, the following data rescue and grid map production steps are generally necessary, including references to GlobalSoilMap specific activities: