Percentage Of Clay Research Articles

Petrographic and Lithofacies of Injana Formation Berman Inticline Northern Iraq

This study is including Petrographic and Lithofacies investigation of Injana Formation North Iraq. The Formation composed of succession of sandstone, siltstone and claystone cycles. The grain size analysis and indicated that the sandstone composed of medium to coarse grains, minor percent silt and clay. The petrographic indicated that the quartz with percent monocrystalline (11-30%) and polycrystalline (4-10%) type , while the feldspar forming mostly of Plagioclace feldspar (2-7.88%) and K-feldspar (5.20-11%). The rocks and fragments mostly of carbonate with percent (15.20- 22.20%) derived from outcrop rocks especially from Fatha and Pilaspi Formation in the area. The recognized clay mineral are; Montmorellonite, palygorskite, kaolinite and chlorite

Persistence of trace metal contamination in a fluvial system: Lahn River, central Germany

To monitor short-term changes in trace metal concentrations (Cu, Pb, Zn) at geomorphically sensitive floodplain locations and examine the persistence of contaminants in the fluvial environment, near-channel sites along the Lahn River, central Germany, that were sampled in 2007 were revisited in 2019. Thirty-three cores were extracted from sites <5 m from the active channel along a 75-km reach of the river. The median concentrations of Cu and Zn in 2019 were statistically unchanged from concentrations in 2007, but median concentrations of Pb in 2019 were statistically higher than in 2007. Concentration of all three trace metals remain above the background concentrations, but only Zn concentrations exceed the 2ϭ background upper limit. On an individual sample site basis, the Cu concentration increased at 48 % of the sites and the Zn concentration increased at 45 % of the sites between 2007 and 2019. Pb concentration increased at 70 % of the sites. Concentrations of trace metals generally increased with distance downstream; the lowermost reach of the Lahn River continues to have the highest concentration of trace metals. Between 2007 and 2019, the concentrations (mean and median) of all three metals increased in the uppermost and lowermost sections of the study area whereas in the middle section the mean and median concentrations of Cu and Zn and the median concentration of Pb decreased (the mean concentration of Pb increased in the middle reach). Changes in metal concentrations between 2007 and 2019 do not appear to be caused by factors such as changes in substrate of samples, variable sedimentation rates and flood history, or the percentage of clay and organic matter content. Elevated concentrations of trace metals persist in near-channel sediments and will continue to pose a risk of future downstream heavy metal pollution in the study reach, especially along the lowermost reach of the Lahn River where the most contaminated sediments are located. Trace metal concentrations in the study reach appear to have become “uncoupled” from overall decreases in metal releases to the environment.

Spatial distribution of status silicon availability for plant and its effect to rice yield

&lt;p&gt;Silicon (Si) is a beneficial element for rice plants. However, evaluating the Si availability status of paddy soil is rarely done. This study aimed to investigate the Si availability for plant (Si&lt;sub&gt;AP&lt;/sub&gt;), spatial distribution, Si&lt;sub&gt;AP&lt;/sub&gt; correlations with some soil properties and the effect of Si&lt;sub&gt;AP&lt;/sub&gt; status on the rice yield. This study used a survey method to collect paddy soil and water sample. The pot experiment method was used to evaluate paddy plant response to Si&lt;sub&gt;AP&lt;/sub&gt; level. Based on K-means, cluster analysis showed that soil Si&lt;sub&gt;AP&lt;/sub&gt; was categorized low (&amp;lt; 147 mg SiO&lt;sub&gt;2&lt;/sub&gt; kg&lt;sup&gt;-1&lt;/sup&gt;), moderate (147 – 224 mg SiO&lt;sub&gt;2&lt;/sub&gt; kg&lt;sup&gt;-1&lt;/sup&gt;) and high (&amp;gt; 224 mg SiO&lt;sub&gt;2 &lt;/sub&gt;kg&lt;sup&gt;-1&lt;/sup&gt;). The Si&lt;sub&gt;AP&lt;/sub&gt; status of the paddy soil area of 26,395 hectares (25%), 61,744 hectares (59%) and 15,952 hectares (15%) was categorized as low, moderate and high, respectively. This present study revealed that the upland area paddy soil has higher Si&lt;sub&gt;AP&lt;/sub&gt; than the lowland area. Total silicon dioxide (SiO&lt;sub&gt;2&lt;/sub&gt;) and clay percentage were negatively correlated with the SiAP in soils. Silicon addition to the paddy soil with Si&lt;sub&gt;AP&lt;/sub&gt; status showed low to high increase in rice yield by 0.2%, 3.9% and 2.7%.&lt;/p&gt;

Aerification Strategies Affecting Golf Green Subsurface Properties

Golf greens often become compacted due to: 1. Construction of less-than-ideal soil containing high percentages of silt and clay. 2. Extensive traffic not only from daily play but continuous maintenance often with heavy machinery. 3. Traffic not being sufficiently curtailed during periods of excessive soil moisture. A two-year field experiment was conducted on a 14-year-old U.S. Golf Association (USGA)-specified Crenshaw creeping bentgrass [Agrostis stolonifera L. var palustris (Huds.)] research putting green in Clemson, SC, to evaluate the effects of varying spring HTA size and timing on turfgrass rooting, soil organic matter (OM) and soil properties. Spring HTA treatments included 1.2-cm i.d. tines spaced at 5.1 cm x 5.1 cm in March and May (standard); 1.2-cm i.d. tines spaced at 3.8 cm x 3.4 cm in March only (2x); 0.9-cm i.d. tines spaced at 3.8 cm x 3.4 cm in March and May; and 0.6-cm i.d. tines spaced at 3.8 cm x 3.4 cm in March, April, May and June. All aerification was to a depth of 7.6 cm, with cores removed. Plots aerified with 0.6-cm tines had the least 2-year reduction in dry root weight (DRW). Plots aerified with 1.2-cm tines in March only (2x) had the greatest reduction in DRW and had the deepest thatch mat depth (TMD) across both years. This “doubling up” treatment would not be advisable on greens where low root mass or thatch accumulation is a concern. Plots aerified with 1.2-cm tines had higher thatch OM content in Year 2. Plots aerified with 0.6-cm tines had higher soil OM content across both years. Repetitive equal depth aerification did not create a layer of increased compaction. Turf managers can vary their spring HTA size and timing to increase TQ during periods where this is important (e.g., for a tournament) with manageable effects on surface, OM, and soil properties.

Estimations of water retention curves for fine-grained soils and tailings using their fractal particle size distributions

A water retention curve (WRC) enables the quick determination of suction in a soil or tailings using the gravimetric water content or degree of saturation. However, establishing the WRC is reliant on time consuming laboratory testing. Here an empirical method is presented that allows the WRC to be estimated quickly, including its void ratio dependency, by relating the fractal and other characteristics of the soil or tailings particle size distributions (PSD) to the parameters which define the WRC. The defining parameters, from a fractal mathematics viewpoint, depend on the particle and pore surface areas and shapes as well as their fractal dimensions. More generally, the clay percentage must also have an important role as it has a major influence on these properties, especially the surface areas. Twelve WRCs for soils and tailings were compiled and compared and used to establish the new empirical expressions. Estimated WRCs using these new empirical expressions compare well with those fitted directly to experimental results. Guidelines are also given on how to quantify suction’s contribution to strength using the location of the hydraulic state on the WRC, adding to the practical appeal of this work.

Fluctation moisture properties in the application of soil dielectric measurement in the North Bengkulu District, Indonesia

Information about soil moisture in the root layer is very important in evaluating water availability for plants, erosion rates and various other hydrological characteristics. Previous research has found a technology for measuring soil dielectric properties as a soil moisture estimator that can be carried out quickly in the field. The purpose of this study was to apply dielectricity technology in estimating the characteristics of soil moisture in situ in the field at the North Bengkulu in Bengkulu Province. Five land units in North Bengkulu Regency, Indonesia, have been selected as experimental sites. At each location, the soil profile was excavated to a depth of 100 cm, the basic characteristics of the soil in each layer were described in the field and analyzed in detail in the laboratory. The variables measured in the field are the measurement of the dielectric properties of the soil, the effective depth of the soil, the horizon and the characteristics of each horizon. The variables analyzed in the laboratory were texture, organic matter in each layer, aggregate stability at 0-10 cm layer, field soil moisture at the time of measurement, and groundwater characteristics. The relationship between the data on the basic characteristics of the soil with the soil moisture balance variable in the laboratory analysis and measurements of dielectric properties in the field, was then determined using regression analysis. The results showed that the five locations studied had different profile characteristics and groundwater fluctuations. Of the four independent variables tested (percentage of sand, silt, clay and organic carbon) then the content of sand and clay can be used as predictors of the water content of field capacity. Because the four independent variables have a very weak correlation with permanent wilting point water, the available water content can only be predicted from the sand and clay content.

Granulometric composition and moisture capacity of the soil in old-age apple orchards of the Lipetsk region

The research was carried out in 2018-2021 in the old fruit-bearing, but not yet uprooted apple orchards of the Lipetsk region. The lowest moisture capacity was determined by the method of gypsum casts, the granulometric composition was determined by the pyrophosphate method. In old age (40-98 years) in apple orchards on chernozems leached in a layer of 10-40 cm of trunk strips, the granulometric composition changes: the proportion of physical sand increases, but the percentage of physical clay decreases. An increase in the proportion of physical sand in the trunk strips occurs mainly due to an increase in the proportion of fine sand (0.05-0.25 mm), and in the aisles an increase in the amount of physical clay occurs due to an increase in the proportion of medium dust (0.001-0.05 mm). With the age of the garden, the decrease in the proportion of physical clay in the trunk strips occurs due to the removal of medium dust (0.001-0.05 mm) and coarse silt (less than 0.001 mm) down the profile. The lowest moisture capacity increases with an increase in the proportion of coarse silt in the soil (r = 0.5), but decreases with an increase in the percentage of medium (r=-0.65) and coarse (r=-0.53) sand. A decrease in the percentage of physical clay in the trunk strips leads to a decrease in the lowest moisture capacity in a layer of 10-40 cm only by the age of the garden of 98 years. The change of the granulometric composition to a lighter one and the reduction of the lowest moisture capacity of the soil in the trunk strips of old apple orchards are evidence of the podzol–forming activity of apple roots.

QUANTITATIVE AND QUALITATIVE CHARACTERIZATION OF THE GRANULOMETRY OF AN INCEPTISOL

Granulometry is an initial factor to be considered in soil research as it plays a fundamental role in physical and chemical properties. The objective of this study was to characterize the granulometric fractions of soil, obtained using the screening and sedimentation method. The Dynamic Light Scattering (DLS), Mid-Infrared (MIR), and Scanning Electron Microscopy with Field Emission Gun (SEM-FEG) techniques were used for this purpose. The quantitative results showed that this soil presents high percentage of clay, followed by fine sand fraction, silt fraction and, finally, the coarse sand fraction. The results obtained by DLS qualify this technique as a procedure to evaluate the quality of the granulometric fractionation of the clay fraction. The MIR analyzes detected characteristic vibrational states of minerals such as kaolinite, halloysite, gibbsite, and quartz. Few works in the literature characterize the clay fraction of the soil without chemical treatment using the SEM-FEG technique. Thus, in this work, pseudo-hexagonal structures were identified, typical of the kaolinite mineral and, to a lesser extent, structures with a filamentous needle-like morphology, which can be ascribed to illite and/or halloysite, whose inorganic functional groups were identified by MIR in the clay fraction of the soil.

Effects of debris-flow and bed composition on erosion and entrainment

Erosion and entrainment of material by debris flows determine debris-flow volume growth and therefore hazard potential. Recent advances in field, laboratory, and modelling studies have distilled two driving forces behind debris-flow erosion; impact and shear forces. A third factor influencing the (relative) importance of these forces is the viscosity and abundance of the interstitial fluid in the debris flow and the bed. However, how erosion and these forces depend on the composition of the debris flow itself and the composition of the bed remains unclear. Here, we present results of small-scale flume experiments with a loosely packed erodible bed that highlight the far-reaching effects of debris-flow and bed composition on erosion processes and magnitude. We quantify the effects of gravel, clay, and solid fraction in the debris flow on bed erosion. In addition, we quantify the effects of water and clay content of the unconsolidated bed on erosion by a debris flow. We show that debris flow erosion increases linearly when the gravel fraction of a debris flow is increased, which is linked to an increase in both impact and shear forces. We find that debris flow erosion, and the related forces, are non-linearly impacted by the clay and water content of the debris flow and those of the bed. For both the clay content of the debris flow and the bed, an optimum in erosion exists around a specific clay percentage that does not directly relate to an optimum in either shear or impact forces. When the water content of the bed and/or the debris flow is increased, erosion becomes largest when supersaturated conditions occur. These conditions are unrelated to the magnitude of the two erodible forces. This shows that both clay and water content affect erosion by affecting the transfer of pore pressures from the debris flow to the bed. We can therefore conclude that impact and shear forces dictate debris flow erosion in most cases but that their (relative) importance is significantly altered by the means and effectivity of pore pressure transfer from the debris flow to the bed. The latter is highly influenced by the viscosity and abundance of the interstitial fluid of the debris flow and the composition of the bed.

The Effect of Prosopis juliflora (Fabaceae) on the Physical and Chemical Properties of Coastal Dune Soil in Western Mexico

Vargas-Lomelín, J.G.; Macías-Rodríguez, M.Á.; Zarazúa-Villaseñor, P.; Rodríguez-Zaragoza, F.A.; Neri-Luna, C., and Albuquerque, F., 2023. The effect of Prosopis juliflora (Fabaceae) on the physical and chemical properties of coastal dune soil in western Mexico. Journal of Coastal Research, 39(1), 63–72. Charlotte (North Carolina), ISSN 0749-0208. Prosopis juliflora (Fabaceae) is a dominant legume and potential ecosystem engineer in the dunes of Jalisco, western Mexico. The objective of the present study was to evaluate how P. juliflora modifies soil physical and chemical properties in three coastal dunes that belong to different watersheds. To determine the physical properties of the three sites, soil samples were taken inside the canopy of five P. juliflora trees and five soil samples were taken outside their canopies. The same trees and soil positions regarding the canopy of P. juliflora were considered to determine the chemical properties, but the samples were taken at two different depths. A multidimensional and permutational analysis of variance (PERMANOVA) was performed to evaluate differences in the physical properties among the sites and between the sampling positions relative to the canopy of P. juliflora. This PERMANOVA also evaluated differences among sites, sample depths, and the positions of the samples relative to the P. juliflora canopy. A test of homogeneity of dispersions was performed to determine the data dispersion type, whereas a similarity percentage analysis identified which variables contributed most to the observed differences. A principal coordinate analysis was performed to visualize the differences in the model. The results demonstrated that P. juliflora modified the soil physical properties, specifically the real density, total porosity percentage, and percentages of silt and clay. The soil physical properties also varied significantly among the three sites. In addition, P. juliflora modified the soil chemical properties, increasing the electrical conductivity, pH, and total nitrogen, iron, and available phosphorus content. The results show significant differences between the two soil depths, as well as among sites. Ultimately, this study contributes to understanding of the implications of soil property modifications by plants in coastal dunes, which will give guidelines for managing and conserving these ecosystems.

Influence of cohesion on California bearing ratio of clay–gravel mixtures

An understanding of the behavior of cohesive sediment is required to solve various engineering problems such as scour around bridge elements, mitigation of soil erosion, pavement design, river bed degradation, stable channel design. Pavement foundation designers principally use the California bearing ratio (CBR) to describe the subgrade and subbase materials and their strength. Several laboratory experiments were done to study the variation in the CBR of cohesive mixtures comprised of clay–gravel mixtures. Nine different clay–gravel mixtures were used in which the clay content varies from 10% to 50% by weight. The variation of the CBR with clay percentage, moisture content, and undrained shear strength parameters was studied. The CBR value reduces with the increase in the moisture content and clay fraction in the mixtures and increases with an increase in the dry density of the mixture under unsoaked conditions. The CBR also increases with the increase of the angle of internal friction of clay–gravel mixtures. A functional relation has been identified to estimate the CBR of clay–gravel mixtures. Using multiple linear regression analysis (MLRA), a relation is proposed to estimate the CBR of clay–gravel mixtures under unsoaked conditions. A statistical analysis was done to judge the behavior of the pertinent variables on the CBR. The proposed relation predicts the CBR of clay–gravel mixtures very well. Artificial neural network (ANN) analysis using R programming was also done to determine the effects of the pertinent variables on the CBR. ANN methodology was applied to predict the contribution of each variable. Three different methods: Garson algorithm, Olden algorithm, and Lek's profile model are used to assess the influence of variable parameters. The Olden algorithm and Lek's profile both show positive association of cohesion with CBR in an unsoaked condition. The role of moisture content was found to be marginally negative in the Olden algorithm and Lek's profile results. It is found that both the ANN and MLRA models are accurate in predicting the CBR of clay–gravel mixtures. It was further found that the MLRA and ANN models are reliable and rapid tools for correct assessment of the CBR of cohesive soil mixtures using the basic soil properties.

Improving the properties of unburned earth to control the interior microclimate

The article concerns the problematics of unburned earth used as material for moulding formwork or clay plaster with lowered contraction, especially about interior unburned earth plaster with the heightened percentage of clay and therefore improved sorption abilities. By adding a plasticizer, it is possible to modify the fluidity of the mixture. With lessening the amount of water it is possible to lower the shrinkage. Furthermore, we can increase the ratio of clay to sand and thus we can control the indoor microclimate. This is because the clay provides adsorption properties. Unburnt clay has been widely used as a building material in the past around the world. In the last century, this material was rather despised. Nowadays, however, this trend is reversing and the unburnt clay is experiencing a renaissance. Increasingly people emphasize ecology, a healthy and balanced indoor climate, and demand buildings with low operational and energy intensity. All this can be offered by unburnt clay, because it is energy-efficient in production, easily accessible in almost all parts of the world, harmless, and beneficial to human health, as clay can contribute to the improvement of the internal microclimate to a much greater extent than other building materials, as confirmed by many scientific findings.

Syringic acid from rice roots inhibits soil nitrification and N2O emission under red and paddy soils but not a calcareous soil.

Syringic acid (SA) is a novel biological nitrification inhibitor (BNIs) discovered in rice root exudates with significant inhibition of Nitrosomonas strains. However, the inhibitory effect of SA on nitrification and nitrous oxide (N2O) emissions in different soils and the environmental factors controlling the degree of inhibition have not been studied. Using 14-day microcosm incubation, we investigated the effects of different concentrations of SA on nitrification activity, abundance of ammonia-oxidizing microorganisms, and N2O emissions in three typical agricultural soils. The nitrification inhibitory efficacy of SA was strongest in acidic red soil, followed by weakly acidic paddy soil, with no significant effect in an alkaline calcareous soil. Potential nitrification activity (PNA) were also greatly reduced by SA additions in paddy and red soil. Pearson correlation analysis showed that the inhibitory efficacy of SA might be negatively correlated with soil pH and positively correlated with clay percentage. SA treatments significantly reduced N2O emissions by 69.1-79.3% from paddy soil and by 40.8%-46.4% from red soil, respectively, but no effect was recorded in the calcareous soil. SA addition possessed dual inhibition of both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) abundance in paddy and red soil. Structural equation modelling revealed that soil ammonium (NH4 +) and dissolved organic carbon content (DOC) were the key variables explaining AOA and AOB abundance and subsequent N2O emissions. Our results support the potential for the use of the BNI SA in mitigating N2O emissions and enhancing N utilization in red and paddy soils.

Applications and Analytical Methods of Ground Penetrating Radar for Soil Characterization in a Silvopastoral System

The use of ground penetrating radar (GPR) for soil characterization has grown rapidly in recent years due to substantial increases in computer processing power and advances in GPR methodologies. However, few studies have focused on applied GPR analysis for soil characterization and decision making in agricultural systems. In this study, we explored applications of some common qualitative and quantitative methods for GPR analysis and characterization of subsurface conditions in a silvopasture system. We analyzed GPR results using traditional visual interpretation methods to delineate depth to bedrock, clay layers, and other important soil features. Estimates of depth to bedrock correlated well with values measured in the field ([Formula: see text]), and estimates of depth to clay layers were marginally correlated with observed values ([Formula: see text]). We also extracted attributes from GPR images to train a random forest regression model to predict coarse fragment percentage and percent clay content. GPR attributes were found to be good predictors of soil coarse fragments, with an R2 value of 0.81 and root mean square error (RMSE) of 18.82 for test data. Our results demonstrate GPR can provide valuable information on subsurface features in silvopastoral systems. These results also suggest a strong potential for machine learning algorithms in GPR data analytics. Data generated using these methods could be integrated with or used to validate existing digital soil mapping methods and contribute to better understanding of subsurface characteristics for optimized soil management in silvopastoral systems.

Impact of water recession and drying on some physical and chemical properties of Abu – Zarak marsh

This study was conducted to investigate the effect of drying and water ebb on some chemical and physical properties of Abu – Zarak marsh. The results showed that the studied pedons characterized by loam texture domination which take gradual trend , wherever texture coarseness increase with increment of distance from marsh center , higher clay percentage found in pedon No.3 which locate in the center of marsh and that is expected because of sedimentation nature and particle translocation gradually with water ebb front . Soil reaction (pH) ranged between (7.46 – 8.00) that’s indicate the studied soils was alkaline because of high percentage of calcite , the results showed that the soil pedons characterized by high values of electrical conductivity (Ec) which ranged between (31.7-70) , (27.3-52.2) , (25.9-94.7) for pedons 1,2,3 respectively. Calcium carbonate ranged between (17-40%) and higher percent recorded in the surface horizon for pedon 2 and lower percent recorded in its followed horizon. This highness produced by parent material effect as add to drying factor which increase calcification process activity. In the other hand the organic matter content was varied between studied pedon 2 (1.7%) and these percents was low as compared with expected values in marsh soils. The results indicate that the cations concentrations varied according to the distance from marsh center and higher percent found in pedon 1 which was (150 , 570 , 180 , 1478 meq/L) for Ca , Mg , K , Na ions respectively , and higher percent of anions which was (1705 , 220 , 0 , 2.8 meq/L) for Cl , So4 , Co3 , Hco3 respectively. The other results showed that the nitrate ion differ from other ions by higher values recorded in the far pedon from marsh center where is pedon 3 which was 307.5 ppm while in the pedon 1 at the center of marsh was 2.5ppm.

The Response of Soil Physicochemical Properties in the Hyrcanian Forests of Iran to Forest Fire Events

When forest fires occur, highly complex effects on soil properties and hydrological processes are activated. However, in countries such as Iran, these consequences are not widely studied and there is a lack of studies. Therefore, the main aim of this study was to investigate the effects of wildfire on soil quality characteristics in a representative forest area located in the Hyrcanian forests, specifically, in the Zarrinabad watershed of Sari. For this purpose, four different sites, including unburnt natural (UNF), burned natural (BNF), unburnt plantation (UPF), and burned plantation forests (BPF) were selected. Soil sampling was performed at each site using the random, systematic method at a depth from 0 to 30 cm. To investigate the effects of fire on physical and chemical properties indicators, 10 plots with dimensions of 0.5 × 0.5 m were placed at a distance of 1.5 m from each other at each site. Soil samples were transported to the laboratory and their physical and chemical properties were determined. The results showed that the percentage of sand, silt, aggregate stability, soil hydrophobicity, organic carbon, organic matter, soil total nitrogen, absorbable potassium and phosphorus, electrical conductivity, and pH, increased significantly when the soil surface is burned (p ≤ 0.01, p ≤ 0.05). However, clay percentage, initial, final, and average infiltration in the burned areas showed a decreasing trend in comparison with other forest statuses. Furthermore, no significant effects were observed on the true and bulk density, porosity, and soil moisture (p ≥ 0.05). These findings demonstrate that forest fire effects in Iran must be considered as a key topic for land managers because soil properties and hydrological processes are drastically modified, and land degradation could be irreparably activated.

Spatio Prediction of Soil Capability Modeled with Modified RVFL Using Aptenodytes Forsteri Optimization and Digital Soil Assessment Technique

To meet the needs of Egypt’s rising population, more land must be cultivated. Land evaluation is vital to achieving sustainable agricultural production. To determine the soil capability in the northeast Nile Delta region of Egypt, the present study introduces a new form of integration between the Agriculture Land Evaluation System (ALES Arid) model and the machine learning (ML) approach. The soil capability indicators required for the ALES Arid model were determined for the 47 collected soil profiles covering the study area. These indicators include soil pH, soil salinity, the sodium adsorption ratio (SAR), the exchangeable sodium percentage (ESP), the organic matter (OM) content, the calcium carbonate (CaCO3) content, the gypsum content, the clay percentage, and the slope. The ALES Arid model was run using these indicators, and soil capability indexes were obtained. Using GIS, these indexes helped to classify the study area into four capability classes, ranging from good to very poor soils. To predict the soil capability, three machine learning algorithms named traditional RVFL, sine cosine algorithm (SCA), and AFO were also applied to the same soil criteria. The developed ML method aims to enhance the prediction of soil capability. This method depends on improving the performance of Random Vector Functional Link (RVFL) using an optimization technique named Aptenodytes Forsteri Optimization (AFO). The operators of AFO were used to determine the best parameters of RVFL since traditional RVFL is sensitive to parameters. To assess the performance of the developed AFO-RVFL method, a set of real collected data was used. The experimental results illustrate the high efficacy of AFO-RVFL in the spatial prediction of soil capability. The correlations found in this study are critical for understanding the overall techniques for predicting soil capability.

The potential for nitrate removal during infiltration: Mapping with machine learning informed by field and laboratory experiments

AbstractManaged aquifer recharge (MAR) can increase groundwater supply and, under some conditions, improve groundwater quality simultaneously. However, the conditions under which water quality improvements can be achieved during infiltration for MAR have not been systematically examined in a spatially explicit manner. This work aims to address that gap by synthesizing observations from laboratory tests, field experiments and operational facilities at four MAR sites within the Pajaro Valley, California, USA to develop a predictive model of nitrate removal during infiltration. We compare two machine learning approaches; random forest and boosted regression trees, to multiple linear regression. The preferred model uses boosted regression trees, with four predictor variables (initial nitrate concentration of infiltrating water, residence time in the soil, soil organic carbon content, and soil percent clay). We apply this model to simulate the spatial distribution of potential nitrate removal (NRp) across a heterogeneous and mixed‐use landscape, finding that &gt;87% of the region has the potential to remove nitrate during infiltration. To link potential nitrate removal capacity to available water for MAR, we combine a map of NRp with independently simulated hillslope runoff, and find that potential load reduction is highest in urban areas (median = 18.8 kg‐N/yr) where large runoff volumes are collocated with soils having high nutrient cycling capacity compared to forested and agricultural areas (median = 1.6 and 3.5 kg‐N/yr, respectively). We analyse potential load reduction across dry, normal, and wet precipitation scenarios, which shows that urban areas have the potential to yield large load reductions (median = 11.3 kg‐N/yr) even under relatively dry conditions. However, much of the generation of elevated nitrate in runoff is associated with agricultural activity. These results suggest that the urban–agricultural interface represents a crucial link between hydrologic and biogeochemical cycles where water supply and quality goals may be met simultaneously. The technical approach used in this study is highly flexible and can help guide decisions in resource management and identify promising MAR sites. More broadly, this approach also elucidates heterogeneity in biogeochemical cycling across complex landscapes.

Effect of Variation in Row Spacing on Soil Wind Erosion, Soil Properties, and Cyperus esculentus Yield in Sandy Land

Cyperus esculentus is highly adaptable to extremely arid conditions and functions of oil extraction and sand fixation. Numerous studies have investigated the influence of row spacing on traditional crop growth and soil physicochemical traits but have not determined how cultivation affects C. esculentus growth and soil properties. Therefore, we conducted a field experiment in a sandy land to explore the responses of the organ yields of C. esculentus, soil wind erosion, and soil properties to row spacing (30, 60, or 90 cm), and bare land was used as the control. The highest plant height, plant density, number of tillers, and organ yields were observed at 30 cm row spacing. However, the lowest degree of soil erosion was also observed at 30 cm row spacing, and the coverage of C. esculentus facilitated soil fixation and conservation. The levels of soil wind erosion in the control plot were 11.7, 3.1, and 4.9 times those at 30, 60, and 90 cm row spacing, respectively. The percentages of clay and silt increased, whereas sand particles decreased with decreasing levels of soil wind erosion. Soil texture improved, and soil nutrients and plant growth were altered. Soil nutrient concentrations, yields, and root nutrient concentrations were positively related to clay percentage and negatively related to sand particles. In addition, the microbial biomass carbon and nitrogen significantly increased in the C. esculentus treatment groups, suggesting that planting C. esculentus promotes the survival and development of microorganisms. Overall, this study indicated that planting C. esculentus can decrease the level of soil wind erosion and improve soil quality. Narrow row spacing (30 cm) has the highest crop yield and soil amelioration and produces optimal ecological and economic benefits.

Evaluation of Soil-Water Characteristic Curve and Pore-Size Distribution of Fine-Grained Soils

A soil’s physical properties, mineral types, and pore structure significantly influence the shape and properties of the soil-water characteristic curve (SWCC). This study investigated the effects of the soil’s physical properties and mineral types on the SWCC and pore-size distribution (PSD). Eight different soils from an alluvial deposit in Istanbul and Adapazarı/Türkiye were used in the study. The test samples were prepared by compaction at optimum water content (OWC) and wet side of optimum water content (wet of OWC). The samples were prepared by consolidation from the slurry. The PSDs of the samples were calculated using the SWCCs and evaluated with scanning electron microscope (SEM) analysis. In addition, the mineral types of all soils were determined by X-ray diffraction analysis. The soil which contains illite-type minerals has higher matric suction than containing kaolin-type. The effect of the clay percentage is more pronounced in silty soils than in plasticity and activity. Soil suction increased with decreasing compaction water content in clayey soils. The air entry water contents rose as the void ratio, liquid limit, clay content, and plasticity increased. The compaction conditions affected the macropore structure more than the micropore structure. In addition, the ratio of macro-micro pore sizes increased with the rise of the compaction water content.