Artigos de revistas: "Spatial variability of soils"

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Rahman, S., L. C. Munn, R. Zhang e G. F. Vance. "Rocky Mountain forest soils: Evaluating spatial variability using conventional statistics and geostatistics". Canadian Journal of Soil Science 76, n.º 4 (1 de novembro de 1996): 501–7. http://dx.doi.org/10.4141/cjss96-062.

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Spatial variability of soils is a landscape attribute which soil scientists must identify and understand if they are to construct useful soils maps. This paper describes the spatial variability of soils in a forested watershed in the Medicine Bow Mountains, Wyoming, using both conventional statistics and geostatistics. Principle Components Analysis indicated that flow accumulation and aspect were the two terrain attributes that most economically described terrain variability. Thickness of A and B horizons, organic carbon and solum coarse fragments were variable in the study area (CVs of 40 to 58%). Simple correlation and regression analyses suggested there were no statistically significant relationships between soil properties (texture, pH, coarse fragments, organic carbon content) and terrain attributes (elevation, slope gradient, slope shape, flow accumulation, aspect). Geostatistical analysis indicated thickness and coarse fragment contents of the A and B horizons, and solum thickness were spatially independent variables; however, pH, organic carbon content, and solum coarse fragment content were spatially correlated. Spatial variability was described by both linear (pH and organic carbon content) and spherical (solum coarse fragment) models. Use of geostatistics provided insight into the nature of variability in soil properties across the landscape of the Libby Creek watershed when conventional statistics (analysis of variance and regression analysis) did not. Key words: Rocky Mountains, Medicine Bow Mountains, forest soils, spatial variability, principle component analysis, geostatistics

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Prasanna, Shwetha. "Analysis of Hydraulic Properties of Indian Forest Soil". Journal of Civil Engineering and Construction 7, n.º 1 (24 de fevereiro de 2018): 12. http://dx.doi.org/10.32732/jcec.2018.7.1.12.

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Soils are a product of the factors of formation and continuously change over the earth’s surface. The analysis of the spatial variability of soil properties is important for land management and construction of an ecological environment. Soils are characterized by high degree of spatial variability due to the combined effect of physical, chemical or biological processes that operate with different intensities and at different scales. The spatial variability of soil hydraulic properties helps us to find the subsurface flux of water. The most frequently used hydraulic properties are soil water retention curve and saturated hydraulic conductivity. Both these hydraulic properties exhibit a high degree of spatial and temporal variability. The primary objective of this study was to analyze the spatial variability of hydraulic properties of forest soils of Pavanje river basin. Correlation analysis technique has been used to analyze various soil properties. Spatial variability of the forested hillslope soils at different depths varied considerably among the soil hydraulic properties. The spatial variability of water retention at all the different pressure head is low at the top layers, and increases towards the bottom layers. The saturated hydraulic conductivity is almost same in the top layers, but more in the bottom layers of forest soil.

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Orfánus, T., Z. Bedrna, Ľ. Lichner, D. Hallett P, K. Kňava e M. Sebíň. "Spatial variability of water repellency in pine forest soil". Soil and Water Research 3, Special Issue No. 1 (30 de junho de 2008): S123—S129. http://dx.doi.org/10.17221/11/2008-swr.

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The variability of water repellency of pine-forest arenic regosols and its influence on infiltration processes were measured in southwest Slovakia. The water drop penetration time (WDPT) tests of soil water repellency and infiltration tests with a miniature tension infiltrometer (3 mm diameter) were performed. Large differences in infiltration were observed over centimetre spatial resolution, with WDPT tests suggesting water repellency varying from extreme to moderate levels. For soils with severe to extreme water repellency determined with WDPT, steady state infiltration was not reached in tests with the miniature tension infiltrometer, making it impossible to estimate sorptivity. Where sorptivity could be measured, the correlation with WDPT was poor. All results suggest that hydraulic properties of soil change below the centimetre scale resolution of the current study, probably due to a presence of unevenly distributed hydrophobic material.

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Hadi, Teeba Abdel Karim Abdel, Amal Radhi Jubeir e Mohammed A. Hussain. "Spatial Variability of Some Soil Microorganisms". IOP Conference Series: Earth and Environmental Science 1158, n.º 2 (1 de abril de 2023): 022023. http://dx.doi.org/10.1088/1755-1315/1158/2/022023.

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Abstract The study area was chosen in the field of the College of Agriculture of Al-Qasim Green University, confined between longitudes 22.6° 22° 044° to 00.9° 24° 0.44° east and between latitudes 19.3° 21° 32° to 21.7° 24° 32° N, and the study area was interlocked and identified The coordinates were obtained by GPS, as samples were obtained from 40 sites of cultivated soils. For two surface depths 0-30 cm and sub-surface 30-60 cm and 40 sites for leftover soils of two depths as well, The volumetric analysis results showed that the variability of the microorganisms in the soil was that the Azotobacter bacteria were the most heterogeneous compared to the Bacillus bacteria, and that the content of Azotobacter was higher in the soil than the Bacillus bacteria, and the agricultural use had an effect on the presence of these microorganisms and their heterogeneity.

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Phontusang, Porntip, Roengsak Katawatin, Krirk Pannangpetch, Sununtha Kingpaiboon e Rattana Lerdsuwansri. "Spatial Variability of Sodium Adsorption Ratio and Sodicity in Salt-Affected Soils of Northeast Thailand". Advanced Materials Research 931-932 (maio de 2014): 709–15. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.709.

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Information on spatial variability of Sodium Adsorption Ratio (SAR) is useful for implementation of appropriate control measures for the salt-affected soils. The major objective of this study was to use geostatistics to describe the spatial variability of (i) the SAR and consequently (ii) the soil sodicity, in areas of different classes of salt-affected soils. Attention was on areas of very severely salt-affected soils (class 1), severely salt-affected soils (class 2), and moderately salt-affected soils (class 3). For each class, 2 study sites were chosen, totally 6 sites were taken into consideration. In each site, 100 soil samples were collected at 0-30 cm depth according to the stratified systematic unaligned sampling method in the dry season of 2012, and analyzed for the SAR in the laboratory. Descriptive statistics and Geostatistics were applied to describe the variability and spatial variability of SAR and soil sodicity, respectively. The result revealed very high variability of SAR. Descriptive statistics showed the CV values of ≥ 35% for every site of every class. When using semivariogram to describe the spatial correlation of SAR, it was found that in 3 study sites, the semivariogram models fitted well with the corresponding semivariogram samples indicating spatial correlation of SAR in the areas. In these cases, the Ordinary Kriging was applied to generate soil sodicity map. The relatively short range values especially for class 1 indicated very high variation of SAR. However, for the other 3 study sites, the linear models were fitted indicating no spatial correlation. Consequently, Trend Surface Analysis was applied instead. According to the soil sodicity maps generated in this study, the areas of class 1 were entirely occupied by strongly sodic soils. For classes 2 and 3, the soils in all study sites belonging to these classes included normal and slightly sodic soils of different proportions. Furthermore, inconsistency of the spatial variability patterns of SAR was found even in areas within the same class of salt-affected soils. As a result, prior to the intensive management of this problem soil in a particular area, investigation on the spatial variability pattern should be performed

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SAMRA, J. S., K. N. S. SHARMA e N. K. TYAGI. "ANALYSIS OF SPATIAL VARIABILITY IN SODIC SOILS". Soil Science 145, n.º 3 (março de 1988): 180–87. http://dx.doi.org/10.1097/00010694-198803000-00004.

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SAMRA, J. S., V. P. SINGH e K. N. S. SHARMA. "ANALYSIS OF SPATIAL VARIABILITY IN SODIC SOILS". Soil Science 145, n.º 4 (abril de 1988): 250–56. http://dx.doi.org/10.1097/00010694-198804000-00003.

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Iqbal, Javed, John A. Thomasson, Johnie N. Jenkins, Phillip R. Owens e Frank D. Whisler. "Spatial Variability Analysis of Soil Physical Properties of Alluvial Soils". Soil Science Society of America Journal 69, n.º 4 (julho de 2005): 1338–50. http://dx.doi.org/10.2136/sssaj2004.0154.

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Hani, Abbas, Narges Sinaei e Ali Gholami. "Spatial Variability of Heavy Metals in the Soils of Ahwaz Using Geostatistical Methods". International Journal of Environmental Science and Development 5, n.º 3 (2014): 294–98. http://dx.doi.org/10.7763/ijesd.2014.v5.495.

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Guérin, Julie, Léon-Étienne Parent e Bing Si. "Spatial and seasonal variability of phosphorus risk indexes in cultivated organic soils". Canadian Journal of Soil Science 91, n.º 2 (maio de 2011): 291–302. http://dx.doi.org/10.4141/cjss10089.

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Guérin, J. É., Parent, L.-É. and Si, B. C. 2011. Spatial and seasonal variability of phosphorus risk indexes in cultivated organic soils. Can. J. Soil Sci. 91: 291–302. Many reports have attributed phosphorus (P) leaching from cultivated organic soils and the eutrophication of adjacent surface waters to P fertilization exceeding the P sorption capacity of the soil. The index of phosphorus saturation (IPS) using the Mehlich III method (M-III) has been proposed to define an agri-environmental threshold of P saturation in cultivated organic soils. The spatial and temporal variability of IPSM-III must be documented and related to the risk of P pollution to recommend more efficient fertilization practices. The objective of this research was to measure spatial and seasonal variation patterns of P in cultivated organic soils and to evaluate the losses of soil test extractable P between autumn and the following spring. Composite soil samples were taken on a 25-× 25-m grid within 7-ha areas in three representative types of cultivated organic soils of southwestern Quebec in fall 2006 and spring 2007. Soil P, iron, and aluminum were extracted in duplicate using the M-III and the acid ammonium oxalate methods (OX). The spatial analysis of organic soils showed that the PM-III and the IPSM-III were spatially autocorrelated and that the experimental semivariograms can be described by linear to sill or spherical models with ranges of 68 to 168 m. There was a high seasonal variability among the PM-III and the IPSM-III values. The IPSM-III values were generally higher than the environmental threshold of 0.05 across sites and sampling periods. Losses of M-III and OX extractable P averaged 41 kg PM-III ha−1 and 84 kg POX ha−1, respectively, between fall and the following spring, suggesting substantial contribution of cultivated organic soils to the pollution of downstream surface waters.

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MacDonald, J. D., e W. H. Hendershot. "Spatial variability of trace metals in Podzols of northern forest ecosystems: Sampling implications". Canadian Journal of Soil Science 83, n.º 5 (1 de novembro de 2003): 581–87. http://dx.doi.org/10.4141/s03-007.

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The concentrations of metals in soils are spatially heterogeneous and soil sampling carried out when studying metals in forest ecosystems is often inadequate. We examined the spatial variability of Cd, Cu, Mn, Ni, Pb and Zn in northern forest ecosystems on a transect with distance from two point source emitters with the goal of providing basic information about the distribution and variability of metals in these soils. Samples were taken under six sampling points at four depths from three experimental sites on each of the two transects. Soils were analysed for acid digestible metals, pH and organic carbon content. Standard deviation, coefficients of variation, mean and medians were analysed for each horizon of each site. It was observed that Cu and Mn variability is higher in closer proximity to the point source while the variability of Zn increased with decreasing soil pH. In Sudbury, emitted metals Ni and Cu accumulate together in soils, whereas in Rouyn-Noranda, with the exception of Cd and Zn, metal concentrations were not related in forest floors. Observations suggest that physical factors influencing where metals are deposited as well as the inherent variability in soil chemical characteristics, and the distance from the point source can all act together to result in high variability in soil metal concentrations in a single forest site. Sampling in the interest of relating vegetation metal concentrations or response to soil metals should be carried out on an individual plant basis with multiple samples taken for each individual. Soil samples taken at intervals of 1 to 1.7 m will provide relative error in estimating soil concentrations of 10% or 20%, respectively. Key words: Spatial variability, trace metals, podzolic soils, smelter emissions

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Obalum, S. E., J. Oppong, C. A. Igwe, Y. Watanabe e M. E. Obi. "Spatial variability of uncultivated soils in derived savanna". International Agrophysics 27, n.º 1 (1 de janeiro de 2013): 57–67. http://dx.doi.org/10.2478/v10247-012-0068-9.

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Abstract The spatial variability of some physicochemical properties of topsoils/subsoils under secondary forest, grassland fallow, and bare-soil fallow of three locations was evaluated. The data were analyzed and described using classical statistical parameters. Based on the coefficient of variation, bulk density, total porosity, 60-cm-tension moisture content, and soil pH were of low variability. Coarse and fine sand were of moderate variability. Highly variable soil properties included silt, clay, macroporosity, saturated hydraulic conductivity, organic matter concentration, and cation exchange capacity. Overall, soil pH and silt varied the least and the most, respectively. Relative weighting showed that location dominantly influenced the soil variability, except for soil porosity and organic matter concentration influenced mostly by land use. Most of the soil data were normally distributed; others were positively skewed and/or kurtotic. The minimum number of samples (at 25 samples ha-1) required to estimate mean values of soil properties was highly soil property-specific, ranging from 1 (topsoil pH-H2O) to 246 (topsoil silt). Cation exchange capacity of subsoils related fairly strongly with cation exchange capacity of topsoils (R2 = 0.63). Spatial variability data can be used to extrapolate dynamic soil properties across a derived-savanna landscape.

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Miller, R. D. "Intrinsic Mesoscopic Spatial Variability in Macroscopically Uniform Soils". Soil Science Society of America Journal 58, n.º 5 (setembro de 1994): 1364–67. http://dx.doi.org/10.2136/sssaj1994.03615995005800050012x.

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Ryan, J. "Spatial variability of soluble boron in Syrian soils". Soil and Tillage Research 45, n.º 3-4 (18 de maio de 1998): 407–17. http://dx.doi.org/10.1016/s0933-3630(97)00037-8.

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Rodrigo Alberto, Saquicela Rojas, Lelly Useche Castro e Ana Francisca Gonzalez Pedraza. "Sampling the spatial variability of grassland soil properties". Minerva 2023, Special (14 de junho de 2023): 74–86. http://dx.doi.org/10.47460/minerva.v2023ispecial.119.

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The properties of grazed grassland soils are frequently degraded in tropical zones. This work aimed to review the literature on the theory and results of sampling and analysis of the spatial variability of pasture soil properties in the world and Ecuador. The methodology, results, and discussion of 15 articles on the subject, available in the following databases: Scopus, SciELO, ScienceDirect, Scimago Journal & Country Rank, Dialnet, and SpringerLink; and the respective theory of 5 books were reviewed. It was found that worldwide there are soil sampling works that evaluate the spatial variability of soil properties; at the national level, sampling does not consider this variability. It is essential to conduct research in Ecuador on the spatial variability of the properties of pasture soils, which will allow reliable decisions to be made for their management and conservation.

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., E. U. Onweremadu. "Spatial Variability of Soil Carbon in Floodplain Soils of Southeastern Nigeria". International Journal of Agricultural Research 2, n.º 6 (15 de maio de 2007): 552–58. http://dx.doi.org/10.3923/ijar.2007.552.558.

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Vanwalleghem, T., J. Poesen, A. McBratney e J. Deckers. "Spatial variability of soil horizon depth in natural loess-derived soils". Geoderma 157, n.º 1-2 (junho de 2010): 37–45. http://dx.doi.org/10.1016/j.geoderma.2010.03.013.

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Sidorovaand, Valeria, e Maria Yurkevich. "Spatial variability of soil properties and its effect on meadow productivity". BIO Web of Conferences 66 (2023): 04003. http://dx.doi.org/10.1051/bioconf/20236604003.

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The spatial heterogeneity of the yield of perennial grasses was studied to identify soil factors that most affect the productivity of sown meadows in South Karelia. Soil variability was studied using various statistical and geostatistical methods. In the course of research, it was found that the best conditions for the growth of perennial grasses are created on soils with a carbon content of about 8% and a slightly acidic or close to neutral reaction environment. It is noted that the type of soil affects the organic carbon content and change in the yield of perennial grasses. In the diagnostic range of peat soils, as the transition from peat-mineral soils to peat soils the organic carbon content in the soil increases and the yield of grasses decreases. The acidity distribution is rather anthropogenic in nature.

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Hernández, A., L. Lugo, A. Mora Garcés, J. Sánchez e E. Arends. "Spatial variability of soils under a slash-burn cultivation system in Amazonas-Venezuela". Forest Systems 12, n.º 2 (1 de agosto de 2003): 43–54. http://dx.doi.org/10.5424/800.

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This paper analyzes, by geostatistical methods, the spatial variability in soil properties between two contrasting soils: under a recently slashed and burned cultivation system and another one 12- year old secondary forest after slash-burn. The soils are located in a Piaroa Community, Sipapo Forestry Reserve, State of Amazonas-Venezuela. In each field was settled a plot of 20 × 20 m and soil samples were taken approximately 5 m apart from each other with a depth from 0 to 20 cm. The data were located spatially in X-Y coordinates for semivariography and mapping by Kriging. The soil of the area was classified as Cambisol Dístrico (Typic Dystrustep), characterized by a low natural fertility, evidenced through high acidity, low content of organic matter, and very low of calcium, potassium, magnesium, sodium and phosphorus, and high content of aluminium. It was demonstrated that the burning affects the spatial variability of the soils attributes analyzed in this investigation, that is to say, somehow favors the space continuity at nearer distances, while in soils that have remained in rest during a certain time, succession on vegetation promotes a bigger diversity of values (different microhabitats) at nearer distances.

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Akbas, F., H. Gunal e N. Acir. "Spatial variability of soil potassium and its relationship to land use and parent material". Soil and Water Research 12, No. 4 (9 de outubro de 2017): 202–11. http://dx.doi.org/10.17221/32/2016-swr.

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Information on the spatial distribution of plant nutrients is a prerequisite to predict their behaviour and to monitor the fertility in a watershed. This study was conducted to evaluate variations of plant available potassium (PAK) and non-exchangeable potassium (NEK) of a watershed with different land use and parent materials. Eight hundred soil samples were taken from 0–30 and 30–60 cm depths across the Kazova watershed of 20 656 ha in size. Average PAK was 152.8 mg/K kg in surface layers and 167.2 mg/kg in subsurface layers. NEK was 925 mg K/kg in surface and 167.2 mg K/kg in subsurface layers. All forms of K were the lowest in soils formed over serpentinite. Soils in pastures had the highest PAK and NEK. Both K forms were positively related to clay content. Spatial variability patterns of PAK and NEK were similar and consistent at both soil depths. The variation in parent material and land use is considered as the main cause for large variations of potassium forms.

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Sharda, Vaishali, Cameron Handyside, Bernardo Chaves, Richard T. McNider e Gerrit Hoogenboom. "The Impact of Spatial Soil Variability on Simulation of Regional Maize Yield". Transactions of the ASABE 60, n.º 6 (2017): 2137–48. http://dx.doi.org/10.13031/trans.12374.

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Abstract. The study of climate variability and its impacts on crop production has become a continuous effort for the scientific community over the past two decades. However, the impact of spatial soil variability along with climatic factors on crop yield remains uncertain. The objective of this study was to determine the impact of soil and climatic variability on maize yield. We used Alabama as a case study because the agriculture is predominantly rainfed and there is a large variability in growing season precipitation due to the influence of climate variability signals such as the El Niño Southern Oscillation (ENSO). The cropping system model CERES-Maize of the Decision Support System for Agrotechnology Transfer (DSSAT) was used to simulate growth, development, and grain yield for maize for the top ten maize-producing counties in Alabama under rainfed conditions during dry and wet ENSO years. Maize yield simulations were compared for one prominent agricultural soil in each county, the top three prominent agricultural soils in each county, and spatially distributed SSURGO soils in each county. Simulated yields were then compared with maize yields reported by the National Agricultural Statistical Services (NASS). The simulation results showed that maize yield was impacted by both climate variability and spatial soil variability. Statistical relationships were established between crop yield, yield changes, and soil properties. This simulation study established the clear importance of soil variability in crop-climate impact studies. Keywords: Crop Modeling, DSSAT, Database, Soil properties, Spatial variability.

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Jamali, Kanwal, Farman Sahito, Zia-ul-Hassan Shah, Naheed Akhter Talpur, Inayatullah Rajpar, Saima Kalsoom Babar, Khalid Hussain Talpur, Javaria Afzal e Zoya Leghari. "Spatial Variability Mapping of Selected Soil Properties of District Tando Allahyar, Sindh, Pakistan". Journal of Applied Research in Plant Sciences 4, n.º 02 (26 de maio de 2023): 625–36. http://dx.doi.org/10.38211/joarps.2023.04.02.188.

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Spatial variability mapping of soil properties is essential to understand the differences among soils found in a geographical region for their better management. This study aimed at spatial variability mapping of selected soil properties of district Tando Allahyar, Sindh which is one of the most important districts of Sindh province. The results revealed that majority of soils (35.6%) had loamy slightly medium-textured type, including 30.8% silt loam, 3.8% loam and 1.0% silt, followed by clayey, fine-textured heavy type (27.9%), including 18.3% clay, 6.7% silty clay and 2.9% sandy clay. Soils with sandy, coarse-textured light type were 20.2%, including 16.3% sandy loam and 1.9% loamy sand and sand each. Soils with loamy, moderately medium-textured type were 16.3%, including 9.6% clay loam and 6.7% sandy clay loam, while silty clay loam soil texture was total missing. The EC ranged from 0.14 to 4.44 dS m-1 (mean: 0.69 dS m-1, mode: 0.42 dS m-1). Majority (91%) of soils had low (46%) to medium (45) level of salinity. Soil pH ranged from 6.2 to 8.6 (mean: 7.7, mode: 8.3). Majority of soils (84%) had either slightly (24%), medium (22%) or strongly alkaline (38%) soil pH. Interestingly, some soils (13%) had slightly acidic pH. Organic matter ranged from 0.10 to 1.6% (mean: 0.64%, mode: 0.17%). Majority (84%) of soils were deficient in organic matter. Soil ABDTPA-P ranged from 1.2 to 18.8 mg kg-1 (mean: 5.38 mg kg-1, mode: 2.4 mg kg-1). More than half (55%) of the soils had low P, while soils with marginal (14%) or adequate (31%) P were also present. Soil ABDTPA-K ranged from 31 to 376 mg kg-1 (mean: 154 mg kg-1, mode: 230 mg kg-1). Majority of soils (62%) had adequate K, while soils with marginal (28%) or low (11%) K were also found. Spatial variability mapping revealed the dominance of loam, sandy clay loam, sandy loam, silty clay and clay loam textures, medium > low and high > salinity, slightly to medium alkaline soils > strongly alkaline soils, low organic matter content, medium to adequate > low soil P, and adequate soil K. The spatial variation found in various soil properties of district Tando Allahyar, Sindh must be taken in mind while deciding about their site-specific management, using the recently developed maps.

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Banerjee, Samiran, e Steven D. Siciliano. "Factors Driving Potential Ammonia Oxidation in Canadian Arctic Ecosystems: Does Spatial Scale Matter?" Applied and Environmental Microbiology 78, n.º 2 (11 de novembro de 2011): 346–53. http://dx.doi.org/10.1128/aem.06132-11.

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ABSTRACTAmmonia oxidation is a major process in nitrogen cycling, and it plays a key role in nitrogen limited soil ecosystems such as those in the arctic. Although mm-scale spatial dependency of ammonia oxidizers has been investigated, little is known about the field-scale spatial dependency of aerobic ammonia oxidation processes and ammonia-oxidizing archaeal and bacterial communities, particularly in arctic soils. The purpose of this study was to explore the drivers of ammonia oxidation at the field scale in cryosols (soils with permafrost within 1 m of the surface). We measured aerobic ammonia oxidation potential (both autotrophic and heterotrophic) and functional gene abundance (bacterialamoAand archaealamoA) in 279 soil samples collected from three arctic ecosystems. The variability associated with quantifying genes was substantially less than the spatial variability observed in these soils, suggesting that molecular methods can be used reliably evaluate spatial dependency in arctic ecosystems. Ammonia-oxidizing archaeal and bacterial communities and aerobic ammonia oxidation were spatially autocorrelated. Gene abundances were spatially structured within 4 m, whereas biochemical processes were structured within 40 m. Ammonia oxidation was driven at small scales (<1m) by moisture and total organic carbon, whereas gene abundance and other edaphic factors drove ammonia oxidation at medium (1 to 10 m) and large (10 to 100 m) scales. In these arctic soils heterotrophs contributed between 29 and 47% of total ammonia oxidation potential. The spatial scale for aerobic ammonia oxidation genes differed from potential ammonia oxidation, suggesting that in arctic ecosystems edaphic, rather than genetic, factors are an important control on ammonia oxidation.

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Mainuri, Zachary Gichuru, e James Odhiambo Owino. "Spatial Variability of Soil Aggregate Stability in a Disturbed River Watershed". European Journal of Economics and Business Studies 9, n.º 1 (6 de outubro de 2017): 278. http://dx.doi.org/10.26417/ejes.v9i1.p278-290.

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Analysis of spatial distribution of soil properties like soil aggregate stability presents an important outset for precision agriculture. The study area was classified into different landscape units according to physiographic features namely: mountains, plateaus, uplands, valleys, pen plains, alluvial plains, lacustrine plains and hills and maps were drawn. The objectives of this study were to evaluate the effects of landscape and land use interaction on the spatial variability of aggregate stability. The variability of aggregate stability exhibited spatial dependence (SDP) which helped in the generation of a spatial dependence index (SDI) that was described using semivariogram models. SPD Gaussian(%) ≤ 25% gave a weak spatial dependence, moderate spatial dependence was given by 25% ( SDP ( % ) ≤ 75% and strong spatial dependence by SDP (%) ) 75%, while SDI Gaussian (%) ≤ 25% gave a strong spatial dependence index while moderate spatial dependence index was indicated by 25% ( SDI (%) ≤ 75%, and weak spatial dependence index SDI (% ) ) 75%. Mean Weight Diameters (MWD) of 0.25 – 0.45 represented unstable soils mostly found in wetlands occurring in valleys, mountains, plains, and depressions in hills, 0 55 –0.62 represented moderately stable soils mostly in agricultural and grassland areas which include plateaus, uplands, and plains, while 0.62 – 0.92 represented stable and very stable soils being found in forested areas, mountains and hills. Various interpolation (kriging) techniques capitalized on the spatial correlation between observations to predict attribute values at unsampled locations using information related to one or several attributes that helped in the construction of an aggregate stability prediction map using Empirical Bayesian kriging (EBK) technique.

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Chartres, C. J. "Soil Spatial Variability". Geoderma 39, n.º 2 (dezembro de 1986): 158–59. http://dx.doi.org/10.1016/0016-7061(86)90074-1.

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Hadas, Amos. "Soil spatial variability". Soil and Tillage Research 9, n.º 1 (janeiro de 1987): 91–93. http://dx.doi.org/10.1016/0167-1987(87)90053-5.

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Nkheloane, T., A. O. Olaleye e R. Mating. "Spatial heterogeneity of soil physico-chemical properties in contrasting wetland soils in two agro-ecological zones of Lesotho". Soil Research 50, n.º 7 (2012): 579. http://dx.doi.org/10.1071/sr12145.

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Wetlands are complex ecosystems, often exhibiting considerable spatial variability, making the understanding of soil spatial relationships within them difficult. A study was conducted to evaluate spatial variability of soil physico-chemical properties in two contrasting wetlands in two agro-ecological zones (AEZs) of Lesotho. Soil samples were collected along two transects in mini-pits dug at different depths at 50-m intervals. The collected samples were analysed for particle size, pH, soil organic carbon (SOC), SOC pool, available phosphorus (Av-P), cation exchange capacity (CEC), and base cations. Results showed that within-site variability was very low for sand particles and pH (coefficient of variation <15% for both properties). Soil physical properties generally showed less spatial heterogeneity than chemical properties, which differed widely within and between the study sites. There was generally low correlation between soil properties, and SOC accounted for most of the variation observed at both sites, especially T’sakholo with partial R2 = 94%; at Thaba-Putsoa, partial R2 = 44%. Geostatistical analysis showed that all of the nugget to sill ratios (NSR) showed strong spatial dependence (i.e. NSR of 54–94%) except SOC (T’sakholo stream-bank) with no spatial dependence, with the nugget accounting for 23.43%. We therefore conclude that further wetland studies in Lesotho should attempt to quantify not only the soil properties or processes under investigation but also their spatial variability, because this spatial variability can provide insight into underlying ecosystem processes and may itself indicate wetland condition. In addition, results of stepwise multiple regression showed that SOC and texture could be used across these sites for the sustainable management of these wetlands.

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Johnson, Mark S., Johannes Lehmann, Tammo S. Steenhuis, Luciélio Vargem de Oliveira e Erick C. M. Fernandes. "Spatial and temporal variability of soil water repellency of Amazonian pastures". Soil Research 43, n.º 3 (2005): 319. http://dx.doi.org/10.1071/sr04097.

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Fire is commonly used to establish and maintain pastures in the Amazon. Fire is also known to induce soil water repellency but few published data exist for the humid tropics. The objectives of this study were to characterise the intensity and spatial variability of water repellency on previously burned pasture soils in the Amazon, and its effect on the nutrient status of the forage grass Brachiaria brizantha (Hochst.) Stapf. Surface soils of pastures and forests in north-western Mato Grosso, Brazil, were found to exhibit soil water repellency using MED and WDPT tests. Soil water repellency was found only within 0–0.01 m of the mineral soil surface, with soil below 0.01 m found to be hydrophilic in all cases. Spatial variability of repellency was high for both pasture and forest soils. For pasture soils, soil water repellency was strongest on recently burned pastures, which exhibited some extremely high values (MED > 8 m). Repellency decreased rapidly with time following burning. Increasing soil water repellency was associated with decreasing N: P ratios of B. brizantha above-ground biomass (r2 = 0.66, P = 0.004). These findings indicate that soil water repellency and pasture productivity are inversely related. Since pasture abandonment fuels continued deforestation, disrupting the processes causing pasture degradation may lead to more sustainable land use in the Amazon.

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Brooker, P. I. "Irrigation equipment selection to match spatial variability of soils". Mathematical and Computer Modelling 33, n.º 6-7 (março de 2001): 619–23. http://dx.doi.org/10.1016/s0895-7177(00)00266-1.

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Bloem, Elke, Silvia Haneklaus, Gerd Sparovek e Ewald Schnug. "SPATIAL AND TEMPORAL VARIABILITY OF SULPHATE CONCENTRATION IN SOILS". Communications in Soil Science and Plant Analysis 32, n.º 9-10 (30 de junho de 2001): 1391–403. http://dx.doi.org/10.1081/css-100104201.

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CAMPBELL, D. J., D. G. KINNIBURGH e P. H. T. BECKETT. "The soil solution chemistry of some Oxfordshire soils: temporal and spatial variability". Journal of Soil Science 40, n.º 2 (junho de 1989): 321–39. http://dx.doi.org/10.1111/j.1365-2389.1989.tb01277.x.

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Simões, J. T., Luis C. Neves, Armando N. Antão e Nuno M. C. Guerra. "Reliability assessment of shallow foundations on undrained soils considering soil spatial variability". Computers and Geotechnics 119 (março de 2020): 103369. http://dx.doi.org/10.1016/j.compgeo.2019.103369.

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Lauzon, John D., Ivan P. O'Halloran, David J. Fallow, A. Peter von Bertoldi e Doug Aspinall. "Spatial Variability of Soil Test Phosphorus, Potassium, and pH of Ontario Soils". Agronomy Journal 97, n.º 2 (março de 2005): 524–32. http://dx.doi.org/10.2134/agronj2005.0524.

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Gravuer, Kelly, Anu Eskelinen, Joy B. Winbourne e Susan P. Harrison. "Vulnerability and resistance in the spatial heterogeneity of soil microbial communities under resource additions". Proceedings of the National Academy of Sciences 117, n.º 13 (12 de março de 2020): 7263–70. http://dx.doi.org/10.1073/pnas.1908117117.

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Spatial heterogeneity in composition and function enables ecosystems to supply diverse services. For soil microbes and the ecosystem functions they catalyze, whether such heterogeneity can be maintained in the face of altered resource inputs is uncertain. In a 50-ha northern California grassland with a mosaic of plant communities generated by different soil types, we tested how spatial variability in microbial composition and function changed in response to nutrient and water addition. Fungal composition lost some of its spatial variability in response to nutrient addition, driven by decreases in mutualistic fungi and increases in antagonistic fungi that were strongest on the least fertile soils, where mutualists were initially most frequent and antagonists initially least frequent. Bacterial and archaeal community composition showed little change in their spatial variability with resource addition. Microbial functions related to nitrogen cycling showed increased spatial variability under nutrient, and sometimes water, additions, driven in part by accelerated nitrification on the initially more-fertile soils. Under anthropogenic changes such as eutrophication and altered rainfall, these findings illustrate the potential for significant changes in ecosystem-level spatial heterogeneity of microbial functions and communities.

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Høgh Jensen, K., e M. B. Butts. "Modelling of Unsaturated Flow in Heterogeneous Soils". Hydrology Research 17, n.º 4-5 (1 de agosto de 1986): 281–94. http://dx.doi.org/10.2166/nh.1986.0020.

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Modelling of soil moisture conditions in spatially variable fields is treated using stochastic methods. Spatial variability of moisture content in a vegetation covered field is partly caused by field variability in soil physical parameters. In the present study a physically based model is coupled with a statistical description of retention properties and saturated hydraulic conductivity respectively to simulate moisture conditions in heterogeneous soils. Results are compared with measurements obtained from two 0.5 ha field sites. Simulations based on the variation in retention properties are shown to account for much of the observed variation in soil moisture conditions with some deficiencies evident close to the soil surface. Variations in saturated hydraulic conductivity alone give an incomplete description of observed variability in soil moisture conditions.

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Wang, Rui, J. Alex Thomasson, Michael S. Cox, Ruixiu Sui e Elizabeth G. Marley Hollingsworth. "Cotton Fiber-Quality Prediction Based on Spatial Variability in Soils". Journal of Cotton Science 21, n.º 3 (2017): 220–28. http://dx.doi.org/10.56454/jzol2651.

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Maximizing cotton fiber quality is crucial for the continued success of the U.S. cotton industry. Previous studies have indicated that spatial variability of fiber-quality properties exists and is a factor in revenue variability across a field. Site-specific fiber-quality prediction potentially could be managed on the farm to optimize fiber quality with respect to profitability, or the harvest could be segregated according to fiber quality to increase a producer’s overall crop price. Fiber micronaire was identified as the target property for study because of its moderate variation at the farm-field level and its importance to producers and the textile industry. Two years’ cotton and soil data from two fields near Brooksville, MS, were used to investigate the extent to which soil parameters could explain spatial variation in cotton fiber quality. Spatial variability existed in both soil and fiber-quality properties, and as expected from prior research, micronaire was found to have relatively large variability compared to other quality properties. Spatial autocorrelation in the data was considered by using Moran’s I but found not to be a factor. When simple linear regression was employed, the individual soil-related factors most closely related to overall micronaire variability were clay content, pH, and relative site elevation. Multiple linear regression was also employed, and one soil variable, pH, accounted for 42% of the overall variability in micronaire for the south field in year one; whereas pH, magnesium, and sodium together accounted for more than 41% of the micronaire variability for the north field in year two. Site-specific prediction of micronaire based on soil parameters alone continues to be a challenge according to the results of this study.

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Wardamı, Al-mabrouk Hamid Hasan, Sabit Erşahin e Gülay Karahan. "Variable rate phosphorus fertilizer recommendations for rainfed wheat". Mediterranean Agricultural Sciences 37, n.º 1 (9 de janeiro de 2024): 41–50. http://dx.doi.org/10.29136/mediterranean.1199628.

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A uniform application of phosphorus (P) fertilizers to spatially variable soils often results in under-fertilization in low P-localities and over-fertilization in high P-localities. This study aimed to evaluate the variable rate applicability of P fertilizers on a 300-ha sloping landscape under rainfed winter wheat cultivation for over 70 years. The soils were sampled (155 samples) using a random spatial sampling technique based on visual differences in soil color and topographic factors. Plant available soil P content (Pav) and other variables of soil samples were analyzed. The spatial variability of Pav was evaluated and the area was divided into three uniform zones (low, medium, high) for fertilizer P application based on the spatial variation of Pav. The values of Pav showed moderate variablity (CV= 21.3%). The fertilizer recommended by the Ministry of Agriculture and Forestry (MAF) was calculated for five identically-sized sub-regions. The results showed that P fertilizer rates calculated for all five sub-regions based on MAF were identical, suggesting that the MAF was insensitive to spatial variability of Pav in the study soils. Both semivariograms and surface maps of soil properties indicated a strong spatial association between Pav and each of plant available water content (PAWC) and aggregate stability index (ASI), suggesting that yield limitation casued by PAWC should be considered in a variable P-application program in the study area. A more comprehensive study is needed to evaluate the efficiency and cost-benefit economics of variable P application in the study soils.

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CARVALHO, LAÉRCIO A. DE, ISMAEL MEURER, CARLOS A. DA SILVA JUNIOR, CRISTIANE F. B. SANTOS e PAULO L. LIBARDI. "Spatial variability of soil potassium in sugarcane areas subjected to the application of vinasse". Anais da Academia Brasileira de Ciências 86, n.º 4 (dezembro de 2014): 1999–2012. http://dx.doi.org/10.1590/0001-3765201420130319.

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When deposited on land the vinasse can promote improvement in fertility, however, often fertilizer application occurs in areas considered homogeneous, without taking into account the variability of the soil. The objective of this study was to evaluate the effect of vinasse application on potassium content in two classes of soils cultivated with sugarcane, and characterize the spatial variability of soil using geostatistical techniques. In the 2010 and 2011 crop year, soil samples were collected from an experimental grid at 0-0.2 and 0.2-0.4 m depth in three soils cultivated with sugarcane, totaling 90 samplings in each grid, for the determination of pH, calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P), aluminum (Al) and potential acidity (H + Al). The data have been submitted to analysis of descriptive statistics and the K attribute was subjected to geostatistical analysis. The coefficient of variation indicated medium and high variability of K for the three soils. The results showed that the spatial dependence of K increased in depth to FRce and decreased to PHlv, indicating that the attribute could have followed the pattern of distribution of clay in depth. The investigation of the spatial variability of K on the surface and subsurface soils provided the definition of management zones with different levels of fertility, which can be organized into sub-areas for a more efficient management of the resources and the environment.

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Qu, Mingkai, Weidong Li e Chuanrong Zhang. "County-Scale Spatial Variability of Macronutrient Availability Ratios in Paddy Soils". Applied and Environmental Soil Science 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/689482.

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Macronutrients (N, P, and K) are essential to plants but also can be harmful to the environment when their available concentrations in soil are excessive. Availability ratios (available concentration/total concentration) of macronutrients may reflect their transforming potential between fixed and available forms in soil. Understanding their spatial distributions and impact factors can be, therefore, helpful to applying specific measures to modify the availability of macronutrients for agricultural and environmental management purposes. In this study, 636 topsoil samples (0–15 cm) were collected from paddy fields in Shayang County, Central China, for measuring soil properties. Factors influencing macronutrient availability ratios were investigated, and total and available concentrations of macronutrients were mapped using geostatistical method. Spatial distribution maps of macronutrient availability ratios were further derived. Results show that (1) availability of macronutrients is controlled by multiple factors, and (2) macronutrient availability ratios are spatially varied and may not always have spatial patterns identical to those of their corresponding total and available concentrations. These results are more useful than traditional soil macronutrient average content data for guiding site-specific field management for agricultural production and environmental protection.

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BASUMATARY, A. "Spatial variability of fertility status in soils of Dima Hasao district of Assam". Annals of Plant and Soil Research 23, n.º 3 (1 de agosto de 2021): 368–74. http://dx.doi.org/10.47815/apsr.2021.10086.

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Two hundred fifty geo-referenced surfaces (0-15 cm) soil samples were collected and analysed for macronutrients and micronutrients to study fertility status in soils of Dima Hasao district of Assam and their relationship with some important soil properties. Soils of the district were found to be extremely acidic to slightly acidic in reaction with a low to high organic carbon content and low in cation exchange capacity. The soil of the district indicated that the available nitrogen, phosphorus and potassium status was observed to the tune of 14.0 %,7.2% and 67.2% under low and 86.0 %, 92.8 % and 32.8 %under medium categories, respectively. The overall percent deficient of exchangeable calcium, magnesium and available sulphur in soils was 25.6, 30.4 and 6.8 %, respectively. Based on critical limit, all soils were adequately supplied with DTPA-extractable Fe, Mn and Cu content. In respect of zinc and boron, soils exhibited 90.4 and 73 per cent under sufficient, while, 2.4 and 12 per cent were found deficient in DTPA -Zn and HWS-B, respectively. Soil pH and EC showed positive correlation with macro nutrients and negative correlation with micronutrients. The macro- and micronutrient showed significant positive relation with soil organic carbon and cation exchange capacity.

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Bogunović, Igor, Igor Đekmeti, Ivan Magdić, Matej Vrbanić, Stefan Matošić e Milan Mesić. "Spatial modelling for describing spatial variability of soil physical properties in eastern Croatia". Poljoprivreda 22, n.º 1 (18 de junho de 2016): 46–52. http://dx.doi.org/10.18047/poljo.22.1.7.

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Marcela, Rohošková, e Borůvka Vít Penížek and Luboš. "Study of Anthropogenic Soils on a Reclaimed Dumpsite and their Variability by Geostatistical Methods". Soil and Water Research 1, No. 2 (7 de janeiro de 2013): 72–78. http://dx.doi.org/10.17221/6508-swr.

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Soils of reclaimed dumpsites after coal mining are considered as typical anthropogenic soils. These soils are at the beginning of their development and have certain specific characteristics. The aim of this study was to describe a soil survey performed on anthropogenic soils of a reclaimed dumpsite, to analyse spatial variability of selected properties using geostatistical methods, and to evaluate the development of reclaimed dumpsite soils. It has been shown that geostatistical methods are suitable for a description of anthropogenic soil properties and their variability. However, characterization of soil properties on the border between areas with different types of reclamation can be difficult due to sharp discontinual transitions caused by human activity. Properties of these soils vary profoundly greatly dependent on the properties of the soil substrate and the type of reclamation. The average content of organic carbon in the topsoil (0–20 cm) was 1.92% on the area covered with a layer of natural topsoil and 0.92% on the area covered by a layer of loess. An initial A horizon can develop even in 10 years under favourable conditions.

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Advincula, M. R. B., e J. T. Padrones. "SPATIAL VARIABILITY OF SOIL PHYSICAL PROPERTIES IN SOUTHERN MANKAYAN, BENGUET, PHILIPPINES". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVIII-4/W8-2023 (24 de abril de 2024): 1–7. http://dx.doi.org/10.5194/isprs-archives-xlviii-4-w8-2023-1-2024.

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Abstract. Hydrothermal alteration in the Mankayan Mineral District in Benguet, Philippines, has had a significant impact on the soil characteristics. Thus, soil characterisation in landslide zones offer useful insights on the nature of slope failure and provide baseline data that may be used with susceptibility mapping and hazard zonations. The study elucidated the physical characteristics of the soils in the southern portion of Mankayan and mapped out the spatial distribution in the area. High sand and low clay content cause low slope stability due to the low water retention in soil, low plasticity, and low shear strength of materials while the resulting porosity led to poor drainage. Results show that the soil's physical properties, whereas most rock units have been affected by alteration, have caused rock deterioration that eventually led to slope failures. The presence of various parent material in the study site influenced the distribution of soil physical properties, specifically the influence of dacite on the Atterberg limits in the central area of southern Mankayan.

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Sen, Rintu, Zachary T. Zambreski e Vaishali Sharda. "Impact of Spatial Soil Variability on Rainfed Maize Yield in Kansas under a Changing Climate". Agronomy 13, n.º 3 (18 de março de 2023): 906. http://dx.doi.org/10.3390/agronomy13030906.

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As the climate changes, a growing demand exists to identify and manage spatial variation in crop yield to ensure global food security. This study assesses spatial soil variability and its impact on maize yield under a future climate in eastern Kansas’ top ten maize-producing counties. A cropping system model, CERES-Maize of Decision Support System for Agrotechnology Transfer (DSSAT) was calibrated using observed maize yield. To account for the spatial variability of soils, the gSSURGO soil database was used. The model was run for a baseline and future climate change scenarios under two Representative Concentration Pathways (RCP4.5 and RCP8.5) to assess the impact of future climate change on rainfed maize yield. The simulation results showed that maize yield was impacted by spatial soil variability, and that using spatially distributed soils produces a better simulation of yield as compared to using the most dominant soil in a county. The projected increased temperature and lower precipitation patterns during the maize growing season resulted in a higher yield loss. Climate change scenarios projected 28% and 45% higher yield loss under RCP4.5 and RCP8.5 at the end of the century, respectively. The results indicate the uncertainties of growing maize in our study region under the changing climate, emphasizing the need for developing strategies to sustain maize production in the region.

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Grabs, T., K. H. Bishop, H. Laudon, S. W. Lyon e J. Seibert. "Riparian zone processes and soil water total organic carbon (TOC): implications for spatial variability, upscaling and carbon exports". Biogeosciences Discussions 9, n.º 3 (14 de março de 2012): 3031–69. http://dx.doi.org/10.5194/bgd-9-3031-2012.

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Abstract. Groundwater flowing from hillslopes through riparian (near stream) soils often undergoes chemical transformations that can substantially influence stream water chemistry. We used landscape analysis to predict total organic carbon (TOC) concentrations profiles and groundwater levels measured in the riparian zone (RZ) of a 67 km2 catchment in Sweden. TOC exported from 13 riparian soil profiles was then estimated based on the riparian flow-concentration integration model (RIM). Much of the observed spatial variability of riparian TOC concentrations in this system could be predicted from groundwater levels and the topographic wetness index (TWI). Organic riparian peat soils in forested areas emerged as hotspots exporting large amounts of TOC. Exports were subject to considerable temporal variations caused by a combination of variable flow conditions and changing soil water TOC concentrations. From more mineral riparian gley soils, on the other hand, only small amounts with relatively time-invariant concentrations were exported. Organic and mineral soils in RZs constitute a heterogeneous landscape mosaic that controls much of the spatial variability of stream water TOC. We developed an empirical regression-model based on the TWI to move beyond the plot scale to predict spatially variable riparian TOC concentration profiles for RZs underlain by glacial till.

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Grabs, T., K. Bishop, H. Laudon, S. W. Lyon e J. Seibert. "Riparian zone hydrology and soil water total organic carbon (TOC): implications for spatial variability and upscaling of lateral riparian TOC exports". Biogeosciences 9, n.º 10 (10 de outubro de 2012): 3901–16. http://dx.doi.org/10.5194/bg-9-3901-2012.

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Abstract. Groundwater flowing from hillslopes through riparian (near-stream) soils often undergoes chemical transformations that can substantially influence stream water chemistry. We used landscape analysis to predict total organic carbon (TOC) concentration profiles and groundwater levels measured in the riparian zone (RZ) of a 67 km2 catchment in Sweden. TOC exported laterally from 13 riparian soil profiles was then estimated based on the riparian flow–concentration integration model (RIM). Much of the observed spatial variability of riparian TOC concentrations in this system could be predicted from groundwater levels and the topographic wetness index (TWI). Organic riparian peat soils in forested areas emerged as hotspots exporting large amounts of TOC. These TOC fluxes were subject to considerable temporal variations caused by a combination of variable flow conditions and changing soil water TOC concentrations. Mineral riparian gley soils, on the other hand, were related to rather small TOC export rates and were characterized by relatively time-invariant TOC concentration profiles. Organic and mineral soils in RZs constitute a heterogeneous landscape mosaic that potentially controls much of the spatial variability of stream water TOC. We developed an empirical regression model based on the TWI to move beyond the plot scale and to predict spatially variable riparian TOC concentration profiles for RZs underlain by glacial till.

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Smirnova, Elena, Kamil Giniyatullin, Ilnas Sahabiev e Liudmila Ryzhikh. "Evaluation of variability of agrochemical properties on agricultural lands in precision farming perspective technologies". BIO Web of Conferences 17 (2020): 00159. http://dx.doi.org/10.1051/bioconf/20201700159.

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Using the example of two crop rotation fields located in the chernozem zone of the Republic of Tatarstan, the spatial variability of soils agrochemical properties was assessed in terms of the application of precision farming technologies when applying mineral fertilizers. It is shown that the use of mixed samples of polygons with an area of 5 ha as an elementary sampling site is sufficient detail for a geostatistical description of the spatial heterogeneity of the agrochemical properties of chernozem soils.

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Shi, Guicai, Yutao Pan, Zhaohua Sun, Yong Liu e Fook-Hou Lee. "Characteristic strength of soils underlying foundations considering effect of spatial variability". Canadian Geotechnical Journal 57, n.º 4 (abril de 2020): 518–36. http://dx.doi.org/10.1139/cgj-2019-0043.

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In Eurocode EC7, a “characteristic” strength is used as a cautious estimate of the local average strength that governs the bearing capacity of the foundation. The objective of this paper is to examine the correlation between the local average strength and the bearing capacity of a stiff caisson foundation resting on spatially variable ground using random finite element analyses. The results show that using the local average strength over some assumed or postulated failure zones tends to overestimate the mean bearing capacity of the ground. This can be attributed to two possible reasons. Firstly, the postulated failure zone is unlikely to be fully reflective of the real failure zone in spatially variable ground. Secondly, the bearing capacity is more affected by the strength of the weak zones than that of the strong zones. Both of these factors lead to a lowering of the bearing capacity. A more indicative way of determining a characteristic strength that will give a better indication of the bearing capacity is also recommended, together with a strength reduction factor that accounts for the effect of spatial variability.

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Giltrap, D. J., e A. E. Hewitt. "Spatial variability of soil quality indicators in New Zealand soils and land uses". New Zealand Journal of Agricultural Research 47, n.º 2 (junho de 2004): 167–77. http://dx.doi.org/10.1080/00288233.2004.9513584.

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Goncharova, O. Yu, O. V. Semenyuk, G. V. Matyshak e L. G. Bogatyrev. "Biological Activity of Urban Soils: Spatial Variability and Control Factors". Eurasian Soil Science 55, n.º 8 (agosto de 2022): 1082–94. http://dx.doi.org/10.1134/s1064229322080038.

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