Distribution Of Soil Physical Properties Research Articles

Modeling the spatial distribution of soil physical properties in a semiarid tropical region

In semiarid regions, sustainably managing the limited available water resources is critical for food, water, and economic security. An important aspect of water management is monitoring, analyzing, and predicting soil moisture and hydrologic fluxes, especially under the threats of climate change. Unfortunately, since monitoring of soil moisture and water fluxes is often sparse in these regions, one needs to rely on hydrological modeling. The latter requires accurate knowledge of soil properties (e.g., texture, porosity, hydraulic conductivity), which in semiarid regions is also complicated by high level of spatial heterogeneity that is not captured by the low density of soil sampling efforts as well as by globally gridded soil databases. Using 300 monitoring sites across the Semiarid region of NE Brazil and a soil moisture model, this study aims to estimate soil properties at the sites through inverse-modeling and then spatially interpolation these properties via geostatistics. Inverse modeling with the Levenberg–Marquardt algorithm accurately captured soil properties across the sites, while clear spatial patterns in these properties allowed us to confidently interpolation them across the region. Comparing our results with a global soil dataset shows that the latter does not capture spatial variability in the region, underlining the need to leverage small scale information. The derived soil property datasets may then particularly be valuable for regional water and ecosystem management applications.

Looking for Optimal Maps of Soil Properties at the Regional Scale

Around 70% of surface in Extremadura, Spain, faces a critical risk of degradation processes, highlighting the necessity for regional-scale soil property mapping to monitor degradation trends. This study aimed to generate the most reliable soil property maps, employing the most accurate methods for each case. To achieve this, six different machine learning (ML) techniques were tested to map nine soil properties across three depth intervals (0–5, 5–10 and > 10 cm). Additionally, 22 environmental covariates were utilized as inputs for model performance. Results revealed that the Random Forest (RF) model exhibited the highest precision, followed by Cubist, while Support Vector Machine showed effectiveness with limited data availability. Moreover, the study highlighted the influence of sample size on model performance. Concerning environmental covariates, vegetation indices along with selected topographic indices proved optimal for explaining the spatial distribution of soil physical properties, whereas climatic variables emerged as crucial for mapping the spatial distribution of chemical properties and key nutrients at a regional scale. Despite providing an initial insight into the regional soil property distribution using ML, future work is warranted to ensure a robust, up-to-date, and equitable database for accurate monitoring of soil degradation processes arising from various land uses.

SPATIAL VARIABILITY OF SOIL PHYSICAL PROPERTIES IN SOUTHERN MANKAYAN, BENGUET, PHILIPPINES

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.

Effects of restoration modes on the spatial distribution of soil physical properties after land consolidation: a multifractal analysis

Effects of restoration modes on the spatial distribution of soil physical properties after land consolidation: a multifractal analysis

Impact of short‐rotation coppice with poplar and willow on soil physical properties

AbstractAs the land area of short‐rotation coppice (SRC) increases, their soil physical impacts have to be evaluated. The objective of this study was to detect the effects of long‐term SRC with poplar and willow on the vertical distribution of soil physical properties (bulk density, water retention, penetration resistance) and on solute transport patterns. An 18‐year‐old SRC located in northeastern Germany was compared to an adjacent continuous arable cropping system by means of soil sampling, penetrologger measurements and dye tracer experiments. The topsoil's bulk density was significantly lower under SRC than under cropland. This effect was especially pronounced in the uppermost 10 cm, where also the air capacity and the plant‐available water content were higher under SRC. The penetration resistance in 25–50 cm depth was reduced under SRC compared to the cropland, indicating a loosening of the plough pan. Dye tracer experiments showed that the importance of preferential flow was higher under SRC due to tree root channels and an increasing colonisation with invertebrates. SRC has ecologically advantageous effects on soil physical properties of the topsoil, however, combined with an enhanced risk of preferential solute transport upon application of agrochemicals.

Effect of Farming Systems on the Spatial Variability of Soil Physical Properties and Soybean Yield

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.

Assessing soil physical properties variability and their impact on vegetation using geospatial tools in Kebbi State, Nigeria

Geospatial distribution of soil physical properties using Geographic Information System (GIS) is essential and efficient to site-specific farming and environmental management processes. This study attempts to evaluate the spatial distribution of soil physical properties and their impact on vegetation status in Kebbi State, Nigeria using the geospatial technique. A total of one hundred and fifty-six (156) soil samples were collected and analysed for soil organic matter (SOM), porosity, texture, Bulk Density (BD) and pH. The data were analyzed both statistically and geospatially to describe the spatial distribution of soil physical properties in the area. The Normalized Difference Vegetation Index (NDVI) was examined on Sentinel 2 satellite imagery. Results show the normal distribution for all parameters, except for soil texture and SOM indicating a positively skewed distribution. The spatial distribution of soil parameters results revealed the existence low to moderate spatial distribution. In comparison to the NDVI, soil properties significantly correlate with vegetation status of the area, except soil porosity which shows an inverse correlation. The study revealed that the use of geospatial technique accurately generates the spatial distribution maps of soil properties in the area and therefore, present a recommendable tool for sustainable land management and environmental management.

Spatial distribution of soil physical properties of alluvial soils: a geostatistical approach

ABSTRACTKnowledge of spatial variation of soil is important in site-specific farming and environmental modeling. Soil particles size and water distribution are most important soil physical properties that governing nearly all of the other attributes of soils. The objectives of this study were to determine the degree of spatial variability of sand, silt and clay contents, and water content at field capacity (FC), permanent wilting point (PWP), and available water content (AWC) of alluvial floodplain soils. Data were analyzed both statistically and geostatistically to describe the spatial distribution of soil physical properties. Soil physical properties showed large variability with greatest variation was observed in sand content (68%). Exponential and spherical models were fit well for the soil physical properties. The nugget/sill ratio indicates except clay all other soil physical properties were moderate spatially dependent (37–70%). Cross-validation of the kriged map shows that prediction of the soil physical properties using semivariogram parameters is better than assuming mean of observed value for any unsampled location. The spatial distribution of water retention properties closely followed the distribution pattern of sand and clay contents. These maps will help to planner to develop the variable rate of irrigation (VRI) for the study area.

Effects of spatial information of soil physical properties on hydrological modeling based on a distributed hydrological model

The spatial distribution of soil physical properties is essential for modeling and understanding hydrological processes. In this study, the different spatial information (the conventional soil types map-based spatial information (STMB) versus refined spatial information map (RSIM)) of soil physical properties, including field capacity, soil porosity and saturated hydraulic conductivity are used respectively as input data for Water Flow Model for Lake Catchment (WATLAC) to determine their effectiveness in simulating hydrological processes and to expound the effects on model performance in terms of estimating groundwater recharge, soil evaporation, runoff generation as well as partitioning of surface and subsurface water flow. The results show that: 1) the simulated stream flow hydrographs based on the STMB and RSIM soil data reproduce the observed hydrographs well. There is no significant increase in model accuracy as more precise soil physical properties information being used, but WATLAC model using the RSIM soil data could predict more runoff volume and reduce the relative runoff depth errors; 2) the groundwater recharges have a consistent trend for both cases, while the STMB soil data tend to produce higher groundwater recharges than the RSIM soil data. In addition, the spatial distribution of annual groundwater recharge is significantly affected by the spatial distribution of soil physical properties; 3) the soil evaporation simulated using the STMB and RSIM soil data are similar to each other, and the spatial distribution patterns are also insensitive to the spatial information of soil physical properties; and 4) although the different spatial information of soil physical properties does not cause apparent difference in overall stream flow, the partitioning of surface and subsurface water flow is distinct. The implications of this study are that the refined spatial information of soil physical properties does not necessarily contribute to a more accurate prediction of stream flow, and the selection of appropriate soil physical property data needs to consider the scale of watersheds and the level of accuracy required.

Effect of management on spatial and temporal distribution of soil physical properties

The purpose of this study was to characterize spatial and temporal variations in soil physical properties and to examine possible differences that might occur when the crop rotation shifted to rice cultivation. Soil samples from 0-20 cm and 20-40 cm depth were collected on a 100×100 m grid basis over a 45 ha field, in May 2005 and May 2011. The geostatistical methods were used to model the variance structure of gravimetric water content (GWC), soil bulk density (BD), penetration resistance (PR) and aggregate stability (AgS). The coefficient of variations were 17.5% for GWC, 7.1% for BD, and 25.0% for PR at surface and 12.8% for GWC, 6.7% for BD, and 17.1% for PR at subsurface. PR at subsurface (>2MPa) and BD at surface and subsurface soils (1.47 g cm-3) exceeded the threshold values in some fields of the study area. Temporal variations of GWC and PR at 0-20 cm and 20-40 cm depths were significant (P<0.01) while BD was significantly varied only at 20-40 cm. Spatial correlation ranges of GWC, BD and PR varied from 72 m to 433 m in 2005 and 40 to 1524 m in 2011. The spatial dependences of GWC, BD and PR at surface were moderate, and AgS had strong dependency at this depth. The spatial distribution maps of soil physical attributes are useful in identifying the limiting factors and take necessary precaution to prevent further loss of soil quality.

Two-dimensional spatial variation of soil physical properties in two tillage systems

Soil physical properties are known to be variable as a result of tillage in both space and time; however, small-scale variations (<1 m) related to tillage are poorly characterized. In this study, morphological descriptions of soil structures created by tillage under conventional (CT) and conservation or mulch (MT) tillage are related to bulk density (qb) and hydraulic conductivity (K) measurements to determine causality and to predict the effects of tillage practices on these properties. Mouldboard ploughing in CT tended to create marked spatial heterogeneity in soil physical properties within the tilled layer, a finding well expressed in the results from morphological description. This method was much less applicable to MT due to a more homogeneous spatial distribution of soil physical properties. Under both tillage systems, rows had higher bulk density values and lower hydraulic conductivity than inter-rows. The global geometric mean of the saturated hydraulic conductivity was higher and more variable under CT than under MT (66 vs. 41 mm⁄ h). Under each tillage system, zones with a high capacity to conduct water were identified (inter-furrows under CT with a mean KS of 720 mm⁄ h, and soil zones with earthworm burrows and cracks in MT with a mean KS of 400 mm⁄ h). In the untilled layer, higher K values were measured under MT than under CT (40 vs. 22 mm⁄ h). The contrast in K between the tilled and the untilled layers was very limited for MT compared to CT where mouldboard ploughing resulted in marked contrast between both layers. The assessment of this small-scale variability in soil physical properties aids our understanding of water and solute movement through topsoil layers.

Variabilidade e correlação espacial de propriedades físicas de solo sob plantio direto e preparo convencional

Os sistemas de manejo do solo influenciam a distribuição espacial das propriedades físicas do solo. Os objetivos deste estudo foram verificar a dependência e a correlação espacial de algumas propriedades físicas do solo por meio do ajuste de dados aos semivariogramas simples e cruzados num Latossolo Vermelho distroférrico, sob plantio direto e preparo convencional, no município de Campo Mourão, Estado do Paraná. Em abril de 2004, realizou-se a amostragem de solo e retiraram-se 128 amostras de solo indeformadas, em malha de 3,0 x 5,0 m, no terço médio da camada de 0-0,15 m de profundidade. Foram determinadas as seguintes propriedades físicas do solo: densidade do solo, macroporosidade, microporosidade, porosidade total, e o conteúdo de água do solo na tensão de 100 hPa ou equivalente à capacidade de campo. Essas propriedades físicas do solo apresentaram semivariogramas simples com maior variabilidade espacial e menor alcance no plantio direto do que no preparo convencional. Contrariamente, os semivariogramas cruzados entre a densidade do solo com a porosidade total ou a capacidade de campo mostraram correlação espacial com menor variabilidade espacial e maior alcance no plantio direto, comparado ao preparo convencional. Os semivariogramas cruzados evidenciaram que a densidade do solo determinou as correlações espaciais com as outras propriedades físicas nos dois sistemas de manejo do solo.

Effects of tractor traffic on spatial variability of soil strength and water content in grass covered and cultivated sloping vineyard

Frequent machinery traffic on sloping vineyard influences spatial distribution of soil physical properties. Our objective was to assess the effects of crawler tractor traffic across the slope (20%) on spatial distribution of soil strength and water content of silt loam soil under controlled grass cover and conventionally cultivated vineyard. The experiment was situated on hillside vineyard (NW, Italy) arranged with rows crosswise the slope. The grass covered treatment included periodical mowing and chopping of herbs and the cultivated treatment—autumn ploughing (18 cm) and spring and summer rotary-hoeing in the vineyard inter-rows (2.7 m). A crawler tractor (2.82 Mg) was used at the same locations across the slope for all tillage and chemical operations. The measurements of soil bulk density, penetration resistance and volumetric water content were done in autumn (after vintage) within the sloping inter-row. The results were analyzed using classic statistics and geostatistics with and without trend. The highest variability was obtained for penetration resistance (CV 56.6%) and the lowest for bulk density (9.6%). In most cases, the semivariograms of the soil parameters were well described by spherical models. The semivariance parameters of all properties measured were influenced by trend. Three-dimensional (3D) maps well identified areas with the highest soil strength in lower crawler ruts being positioned in the upper side of vine row and successively lower strength in upper ruts situated on other side of the same row and inter-rut area. Higher strength in lower than upper ruts was induced by tractor's tilt and resulting higher ground contact pressure. Soil water content in both treatments was the lowest below the upper rut and increased in inter-rut and lower rut areas. The differences in the soil properties between the places within the inter-row were more pronounced in grass covered than in cultivated soil.

The effects of landscape attributes and plant community on soil physical properties in rangelands

This study addressed the effect of landscape attributes on the spatial distribution of soil physical properties in an alpine rangeland in a semi-arid area of Iran. Soil physical properties are recognized for their important role in supporting plant growth. To identify the effects of landscape attributes on soil physical properties the present study collected and analysed information from air photos, satellite images, field survey, and the laboratory using statistical analyses. Land stratification allowed the study area to be subdivided into Land Unit Tracts (LUT), according to specified criteria including landform attributes (slope, aspect, and altitude) and vegetation type. A factorial model on the basis of a completely randomised design was used to analyse the data collected from 234 LUT. The interrelationships between soil physical properties and landscape attributes were investigated and interpreted based on statistical analysis and expert knowledge. Slope significantly ( P<0.05) affected most properties of the 0–10 cm topsoil including grade of pedality and slake test. Also, many soil properties that reflect parent material and likely to be related to soil moisture status including coarse fragment ratio, soil profile effective thickness, first layer effective thickness, water retention capacity, and depth to water table were significantly related to slope gradient. These soil properties noticeably affect range productivity.

Simultaneous modeling of transient three-dimensional root growth and soil water flow

A model is presented for the simultaneous, dynamic simulation of soil water movement and plant root growth. Root apices are translocated in individual growth events as a function of current local soil conditions. A three-dimensional finite-element grid over the considered soil domain serves to define the spatial distribution of soil physical properties and as framework for the transient water flow model. Examples illustrate how field-observed morphology of root systems can be approximated by including even a coarsely discretized description of the soil environment. Intended as a tool for testing of hypotheses on soil-plant interaction, simulations can be performed for different levels of model complexity, depending on how much information is available. At the simplest level, root growth is simulated without soil water uptake, whereas the most comprehensive level includes growth of the shoot and dynamic assimilate allocation to root and shoot.