scholarly journals Spatial variability of saturated hydraulic conductivity and its links with other soil properties at the regional scale

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Boguslaw Usowicz ◽  
Jerzy Lipiec

AbstractSaturated hydraulic conductivity (K) is a key property for evaluating soil water movement and quality. Most studies on spatial variability of K have been performed soil at a field or smaller scale. Therefore, the aim of this work was to assess (quantify) the spatial distribution of K at the larger regional scale in south-eastern Poland and its relationship with other soil properties, including intrinsic sand, silt, and clay contents, relatively stable organic carbon, cation exchange capacity (CEC) and temporally variable water content (WC), total porosity (FI), and dry bulk density (BD) in the surface layer (0–20 cm). The spatial relationships were assessed using a semivariogram and a cross-semivariogram. The studied region (140 km2) with predominantly permeable sandy soils with low fertility and productivity is located in the south-eastern part of Poland (Podlasie region). The mean sand and organic carbon contents are 74 and 0.86 and their ranges (in %) are 45–95 and 0.002–3.75, respectively. The number of individual samples varied from 216 to 228 (for K, WC, BD, FI) to 691 for the other soil properties. The best fitting models were adjusted to the empirical semivariogram (exponential) and the cross-semivariogram (exponential, Gaussian, or linear) used to draw maps with kriging. The results showed that, among the soil properties studied, K was most variable (coefficient of variation 77.3%) and significantly (p < 0.05) positively correlated with total porosity (r = 0.300) and negatively correlated with soil bulk density (r = – 0.283). The normal or close to the normal distribution was obtained by natural logarithmic and root square transformations. The mean K was 2.597 m day−1 and ranged from 0.01 up to 11.54 m day−1. The spatial autocorrelation (range) of K in the single (direct) semivariograms was 0.081° (8.1 km), while it favourably increased up to 0.149°–0.81° (14.9–81 km) in the cross-semivariograms using the OC contents, textural fractions, and CEC as auxiliary variables. The generated spatial maps allowed outlining two sub-areas with predominantly high K above 3.0 m day−1 in the northern sandier (sand content > 74%) and less silty (silt content < 22%) part and, with lower K in the southern part of the study region. Generally, the spatial distribution of the K values in the study region depended on the share of individual intrinsic textural fractions. On the other hand, the ranges of the spatial relationship between K and the intrinsic and relatively stable soil properties were much larger (from ~ 15 to 81 km) than between K and the temporally variable soil properties (0.3–0.9 km). This knowledge is supportive for making decisions related to land management aimed at alteration of hydraulic conductivity to improve soil water resources and crop productivity and reduce chemical leaching.

2021 ◽  
Author(s):  
Boguslaw Usowicz ◽  
Jerzy Lipiec

Abstract Saturated hydraulic conductivity (SHC) is a key property for evaluating soil water movement and quality. Most studies on spatial variability of SHC have been performed soil at a field or smaller scale. Therefore, the aim of this work was to assess (quantify) the spatial distribution of SHC at the commune scale and its relationship with other soil properties, including intrinsic sand, silt, and clay contents, relatively stable organic carbon, cation exchange capacity (CEC), dynamic water content (WC), total porosity (FI), and dry bulk density (BD) in the surface layer (0–20 cm). The spatial relationships were assessed using a semivariogram and a cross-semivariogram. The studied commune (140 km2) with predominantly permeable sandy soils with low fertility and productivity is located in the south-eastern part of Poland (Podlasie region). The mean sand and organic carbon contents are 74 andobablyctknąć, czy o to chodzid mniej znacznie mniejszed? ? 0.86 and their ranges (in %) are 45-95 and 0.002-3.75, respectively. The number of individual samples varied from 216–228 (for SHC, WC, BD, FI) to 691 for the other soil properties. The best fitting models were adjusted to the empirical semivariogram (exponential) and the cross-semivariogram (exponential, Gaussian, or linear) used to draw maps with kriging. The results showed that, among the soil properties studied, SHC was most variable (coefficient of variation 77.3%) and significantly (p <0.05) positively correlated with total porosity (r = 0.300) and negatively correlated with soil bulk density (r = –0.283). The mean SHC was 2.597 m day–1 and ranged from 0.01 up to 11.54 m day–1. The spatial autocorrelation (range) of SHC in the single (direct) semivariograms was 0.081° (8.1 km), while it favourably increased up to 0.149–0.81° (14.9–81 km) in the cross-semivariograms using the OC contents, textural fractions, and CEC as auxiliary variables. The generated spatial maps allowed outlining two sub-areas with predominantly high SHC above 3.0 m day–1 in the northern sandier (sand content >74%) and less silty (silt content <22%) part and, with lower SHC in the southern part of the commune. Generally, the spatial distribution of the SHC values in the commune area depended on the share of individual intrinsic textural fractions. On the other hand, the ranges of the spatial relationship between SHC and the intrinsic and relatively stable soil properties were much larger (from ~15 to 81 km) than between SHC and the dynamic soil properties (0.3-0.9 km). This knowledge is supportive for making decisions related to land management aimed at reduction of hydraulic conductivity and chemical leaching and improvement of soil water resources and crop productivity.


Weed Science ◽  
1999 ◽  
Vol 47 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Rubem S. Oliveira ◽  
William C. Koskinen ◽  
Francisco A. Ferreira ◽  
Bhairav R. Khakural ◽  
David J. Mulla ◽  
...  

A significant limitation in using sorption coefficients (Kd) to predict solute transport through natural soils is the spatial variability of soil properties over large field areas. Spatial variability inKdfor imazethapyr was determined on representative samples from a 31.4-ha field, covering a pH range from 4.9 to 7.6 and an organic carbon (OC) range from 1.45 to 5.80 g kg−-1.Kdvaried from 0.18 to 3.78 across the field, with an average value of 1.56. The analysis ofKdvariability showed two distinct patterns in spatial distribution: areas in which pH > 6.25 andKd< 1.5, whereKdvariation is based primarily on pH, and areas in which pH < 6.25 andKd> 1.5, where other soil properties, i.e., OC content, have a significant influence onKdvariation. Based on soil pH distribution, an easily measured property, the field was divided into two potential management areas. This separation allowed identification of portions of the field where herbicide sorption would be minimal, with a relatively higher potential for leaching (i.e., areas withKd< 1.5), and provided a rationale for site-specific imazethapyr application.


2021 ◽  
Vol 7 ◽  
Author(s):  
Kouseya Choudhuri ◽  
Debarghya Chakraborty

This paper intends to examine the influence of spatial variability of soil properties on the probabilistic bearing capacity of a pavement located on the crest of a fibre reinforced embankment. An anisotropic random field, in combination with the finite difference method, is used to carry out the probabilistic analyses. The cohesion and internal friction angle of the soil are assumed to be lognormally distributed. The Monte Carlo simulations are carried out to obtain the mean and coefficient of variation of the pavement bearing capacity. The mean bearing capacity of the pavement is found to decrease with the increase in horizontal scale of fluctuation for a constant vertical scale of fluctuation; whereas, the coefficient of variation of the bearing capacity increases with the increase in horizontal scale of fluctuation. However, both the mean and coefficient of variation of bearing capacity of the pavement are observed to be increasing with the increase in vertical scale of fluctuation for a constant horizontal scale of fluctuation. Apart from the different scales of fluctuation, the effects of out of the plane length of the embankment and randomness in soil properties on the probabilistic bearing capacity are also investigated in the present study.


PLoS ONE ◽  
2015 ◽  
Vol 10 (3) ◽  
pp. e0119175 ◽  
Author(s):  
Houxi Zhang ◽  
Shunyao Zhuang ◽  
Haiyan Qian ◽  
Feng Wang ◽  
Haibao Ji

2020 ◽  
Vol 28 (8) ◽  
pp. 2657-2674
Author(s):  
Markus Theel ◽  
Peter Huggenberger ◽  
Kai Zosseder

AbstractThe favorable overall conditions for the utilization of groundwater in fluvioglacial aquifers are impacted by significant heterogeneity in the hydraulic conductivity, which is related to small-scale facies changes. Knowledge of the spatial distribution of hydraulically relevant hydrofacies types (HF-types), derived by sedimentological analysis, helps to determine the hydraulic conductivity distribution and thus contribute to understanding the hydraulic dynamics in fluvioglacial aquifers. In particular, the HF-type “open framework gravel (OW)”, which occurs with the HF-type “bimodal gravel (BM)” in BM/OW couplings, has an intrinsically high hydraulic conductivity and significantly impacts hydrogeological challenges such as planning excavation-pit drainage or the prognosis of plumes. The present study investigates the properties and spatial occurrence of HF-types in fluvioglacial deposits at regional scale to derive spatial distribution trends of HF-types, by analyzing 12 gravel pits in the Munich gravel plain (southern Germany) as analogues for outwash plains. The results are compared to the reevaluation of 542 pumping tests. Analysis of the HF-types and the pumping test data shows similar small-scale heterogeneities of the hydraulic conductivity, superimposing large-scale trends. High-permeability BM/OW couples and their dependence on recognizable discharge types in the sedimentary deposits explain sharp-bounded small-scale heterogeneities in the hydraulic conductivity distribution from 9.1 × 10−3 to 2.2 × 10−4 m/s. It is also shown that high values of hydraulic conductivity can be interpolated on shorter distance compared to lower values. While the results of the HF-analysis can be transferred to other fluvioglacial settings (e.g. braided rivers), regional trends must be examined with respect to the surrounding topography.


2018 ◽  
Vol 22 (4) ◽  
pp. 239-249 ◽  
Author(s):  
William Mario Fuentes ◽  
Carolina Hurtado ◽  
Carlos Lascarro

Sand-clay mixtures are one of the most usual types of soils in geotechnical engineering. These soils present a hydraulic conductivity which highly depends on the fine content. In this work, it will be shown, that not only the mean fine content of a soil sample affects its hydraulic conductivity, but also its spatial distribution within the sample. For this purpose, a set of hydraulic conductivity tests with sand-clay mixtures have been conducted to propose an empirical relation of the hydraulic conductivity depending on the fine content. Then, a numerical model of a large scaled hydraulic conductivity test is constructed. In this model, the heterogeneity of the fine content is simulated following a Gaussian distribution. The equivalent hydraulic conductivity resulting of the whole model is then computed and the influence of the spatial distribution of the fine content is evaluated. The results indicate that the hydraulic conductivity is not only related to the mean fine content, but also on its heterogeneity.


2019 ◽  
Vol 11 (15) ◽  
pp. 87
Author(s):  
Ligia Maria Lucas Videira ◽  
Paulo Ricardo Teodoro Silva ◽  
Diego dos Santos Pereira ◽  
Rafael Montanari ◽  
Alan Rodrigo Panosso ◽  
...  

In no-tillage (NT) and minimum tillage (MT) areas, spatial variability of soil physical properties may affect crop yield. The aim of this study was to assess the spatial distribution of soil physical properties, as well as the yield components and grain yield of soybean (GY), based on the mapping of areas under soil conservation farming systems. We assessed yield components, GY and the physical properties of an Oxisol, under NT and MT using the t-student test, and geostatistics to assess spatial variability. The largest population of NT plants showed no spatial dependence and did not influence GY, but the components related to plant height and soil properties differed between systems. From a spatial standpoint, the kriging maps demonstrated that mass of one thousand grains (MOG), total porosity (TP) and soil bulk density (BD) influenced GY under NT, whereas TP1 exerted the most influence under high soil moisture conditions and MT. The maps make it possible to assess the spatial distribution of soil physical properties and the influence on GY, making them an important tool for more accurate production planning in soil conservation systems.


Author(s):  
Utin U. E ◽  
Essien G. E

A study was conducted to determine the effects of slope position and fertilizer type on soil properties and growth of maize (Zea mays) on Coastal Plain Sands of Akwa Ibom State, Nigeria. Results obtained showed that soils of lower slope (LS) had the highest contents of clay and silt compared with those of upper slope (US) position. Bulk density of the upper slope soil and that of the middle slope (MS) soils were significantly higher (P≤0.05) than that of LS soil and subsequently, total porosity and saturated hydraulic conductivity (Ksat) increased downslope. Bulk density of soils that received poultry manure (PM) and NPK+PM were significantly reduced compared to those of NPK and control while total porosity and Ksat of soils that received PM and NPK+PM were significantly higher (P≤0.05) than those of NPK and control. Soils of LS had highest pH, organic carbon, total nitrogen, available phosphorus, ECEC compared to those of MS and US. The application of poultry manure yielded increase in soil pH, soil organic carbon, total nitrogen, available phosphorus and ECEC when compared to soils of NPK and control. Growth of maize obtained with LS were consistently higher than those of the MS and US soils. Soils of LS that received NPK and NPK+PM had consistently similar maize growth, higher than other combinations of slope position and fertilizer type. The complementary application of poultry manure and NPK 15:15:15 can be the best option for increasing the fertility of soils with varying slope positions on Coastal Plain Sands.


Author(s):  
Vítězslav Vlček ◽  
Martin Brtnický

The erosion impact on the spatial variability of selected soil properties was picked for the purpose of the research. The chosen locality is situated close to Křenovice (Vyškov district). Sites with soil type chernozem are exploited as arable land almost everywhere in this region. The agricultural production, however, has had staggering impact during last 80 years and has caused many degradation changes of soil properties of chernozems. This work aims to point out the water erosion impact on the spatial variability of total nitrogen, total organic carbon and C/N ratio, at steep grounds with no soil protection from erosion on loess parent material.


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