Soil Mineralogy Research Articles

Unified Elastic Modulus Characteristic Curve Equation for Variably Saturated Soils

A soil’s elastic modulus is a fundamental property defining the soil’s reversible stress-strain relation under mechanical and environmental loadings. It has been observed that a soil’s elastic modulus can increase up to several orders of magnitude from fully saturated to dry conditions due to two distinct soil water retention mechanisms: adsorption and capillarity. Adsorption affects interparticle stress through van der Waals and electrostatic attraction and interparticle friction coefficient through water film retained by soil sorptive potential. Capillarity governs interparticle stress through capillary pressure and surface tension. The onset and scaling laws of the two mechanisms depend on the soil properties of specific surface area, pore-size distribution, cation exchange capacity, and soil mineralogy. These mechanisms are unified by a proposed elastic modulus characteristic curve (EMCC) equation. It is demonstrated that the proposed EMCC equation can well describe the moisture-dependent elastic modulus of a wide array of soils. Further, an interrelation among the EMCC equation, suction stress and soil shrinkage curves is established, which can greatly facilitate predicting suction stress from soil shrinkage curves and vice versa, further validating the EMCC equation in capturing soil’s hydromechanical behavior. The practical importance of the EMCC equation is demonstrated through prediction of ground heave of various soils due to a hypothetical flooding event.

Soil science education: A multinational look at current perspectives

AbstractSoil knowledge is essential to address modern global challenges. Soil science education began with soil survey and agricultural activities, with a focus on the traditional subdisciplines of soil chemistry, soil physics, pedology, soil mineralogy, and soil biology. Soil education has evolved to address the needs of an increasing variety of fields and increasingly complex issues, as seen through the move to teach soil content in programs such as biological and ecological sciences, environmental science, and geosciences. A wide range of approaches have been used to teach soil topics in the modern classroom, including not only traditional lecture and laboratory techniques but also soil judging, online tools, computer graphics, animations, and game‐based learning, mobile apps, industry partners, open‐access materials, and flipped classrooms. The modern soil curriculum needs to acknowledge the multifunctionality of soils and provide a suite of conduits that connect its traditional subdisciplines with other cognate areas. One way to accomplish this may be to shift from the traditional subdiscipline‐based approach to soil science education to a soil functions approach. Strategies to engage the public include incorporating soil topics into primary and secondary school curricula, engaging the public through museums and citizen science projects, and explaining the significance of soil to humanity. Soil education has many challenges and opportunities in the years ahead.

Geotechnical Characterization of Termite Mound Soils of Congo

This study is to determine the activities and correlations in the fundamental properties of the termite mounds soils Cubitermes spp and Macrotermes sp. The Intrinsic properties depend on the mineralogy, organic composition and texture of soil. Grain size, Atterberg limits and soil blue values are geotechnical properties that were used to characterize the two soils. On the basis of the geotechnical properties, specific surface area, cation exchange capacity, relative activity, surface activity and soil activity were determined. The correlations obtained in the intrinsic soil properties are linear and polynomial fits. Indeed, the relationship between the plasticity index and the blue value of a soil on the one hand and between the specific surface area and the cation exchange capacity on the other hand, is a linear fit for all soils in general. The relationship between plasticity index and specific surface area is a linear fit for the soils (C, M). Correlations in intrinsic soil properties that have a coefficient of determination close to 1 can be used in geotechnical engineering to predict one of the two desired parameters.

Characteristics and Mineralogy of Some Clay Rich Soils of the Lower Indo-Gangetic Plains of Murshidabad District, West Bengal

Characteristics and Mineralogy of Some Clay Rich Soils of the Lower Indo-Gangetic Plains of Murshidabad District, West Bengal

Genesis and mineralogy of teak-supporting soils in Seoni district of Madhya Pradesh

Five typical pedons having their parental legacy with basalt and occurring on different landforms were studied in forest area of Seoni district, Madhya Pradesh for understanding their mineral make-up and genesis. Semi-quantitative analysis of clay fractions indicated that soils clays are dominant in smectites followed by vermiculite (P1), kaolin (P3 and P5) and mica with traces of quartz and feldspar in all the pedons, barring pedon 4, which was dominated by kaolin. Inspite of the similar parent material and climatic condition, the formation of Alfisols, Entisols and Inceptisols might be attributed to the effect of climate, slope and/or drainage. The presence of kaolin and non-calcareous nature, indicated that these soils were formed initially under an earlier humid climate, while smectites, developed on depressions were retained up to the present climate due to non-leaching environment.

Effects of lead contaminants on engineering properties of Iranian marl soil from the microstructural perspective

Most of the industries in the south of Iran and north of the Persian Gulf are built on marl bedrocks and these industries are major sources of heavy metal pollutants. Therefore, the engineering properties of marl soils contaminated with heavy metals (particularly lead ions) are worthy of thorough investigation. This was accomplished by artificial contamination of marl soil with varying lead concentrations and measurment of some geotechnical (granularity, Atterberg limits, compressive strength, and permeability) and geo-environmental (CEC, pH, and contaminant retention) characteristics. In addition, with the aid of X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images the changes in mineralogy and microstructural behavior of lead-contaminated soil were investigated. According to the findings of the present study, marl soil can hold about 200 cmol/kg-soil of lead concentration. As seen by SEM images, the lead precipitation changed the soil's geotechnical properties by altering the structure and texture of soil (notably flocculation). At 100 cmol/kg-soil lead concentration, the compressive strength was reduced by about 85%, while the hydraulic conductivity increased up to 170 times. Adding lead to the marl soil decreased the intensity of X-ray diffraction peaks for the main clay minerals and created new peaks associated with precipitated cerussite, shannonite, and leadhillite.

Mineralogy of Alluvial Soils Developed in Narmada River Basin in West Coast of Gujarat

Clay minerals have played a significant role for the plant nutrient management for crop production. Soils of recent and old alluvial plains deposited by Narmada river in Jhagadia block were investigated for their mineralogical makeup. The soils on recent alluvial plains (P1) (Fluventic Haplustepts) are very deep, moderately well drained, very dark grayish brown to very dark brown, silt loam to silt clay loam on level to nearly level slope with clay loam surface and slight erosion. The soils of old alluvial plain (P2) (Vertic Haplustepts) are similar to recent alluvial plain with clayey texture and moderate erosion. The pedons were sampled at one km (recent alluvial plain) and at two km (old alluvial plain) distance from Narmada river stream. The soils of recent alluvial plain are slightly alkaline (pH 7.5-8.5), slightly calcareous (<5% CaCO3) with moderate cation exchange capacity (CEC) and high in base saturation (>90%). The soils of old alluvial plain have high CEC and CaCO3 in sub-surface horizons. This paper presents a detailed study on clay minerals in surface and sub-surface sediments deposited by the Narmada river drainage basin. Clay content was ranged from 30-50% in recent alluvia and 50-60% in old alluvia. The soils of recent alluvia were high in silt fraction (40-47%) which plays an active role in potassium nutrition. The smectite content was significantly higher (weighted mean 64.9%) in old alluvial plain compared with recent plain (weighted mean 37.8%). A reverse pattern of mica distribution was observed in clay fraction of both the plains. The distribution of quartz and K/Na feldspars showed similar trends in sand fraction but wide variability was observed in the case of hydralsite, kenyaite, and boehmite content with depth. The mineralogical study indicated that the clay mineral assemblage of both sites varied in smectites and mica, which imparts heterogeneity to soil properties.

Clay Mineralogy of Soils Developed on Miocene Marls of Mt. Medvednica, Nw Croatia: Origin and Transformations in Temperate Climate

Clay Mineralogy of Soils Developed on Miocene Marls of Mt. Medvednica, Nw Croatia: Origin and Transformations in Temperate Climate

The Pedospheric Variation of DTPA-Extractable Zn, Fe, Mn, Cu and Other Physicochemical Characteristics in Major Soil Orders in Existing Land Use Systems of Punjab, India

The agricultural production in Punjab has increased manifold that aggravated the deficiencies of micronutrients in soils and plants. The availability of soil micronutrients in different soil orders depends upon the soil mineralogy, topography, climatic conditions and cropping sequences. Hence, to study the pedospheric variations of DTPA-extractable micronutrients, viz., zinc (Zn), iron (Fe), manganese (Mn) and copper (Cu), in three prominent soil orders of Punjab, a total of 144 depth-wise soil samples were collected from four major land-use systems (cultivated, horticulture, forest and pasture lands). The DTPA extractable micronutrients varied from 1.74–2.81, 1.83–2.82 and 1.81–2.80 for Zn; 5.3–6.8, 5.6–6.9, 4.3–6.3 for Fe; 5.1–7.8, 5.5–7.9, 5.4–7.5 for Mn; and 0.84–1.40, 0.93–1.68, 0.87–1.65 for Cu in soil orders Aridisol, Entisol and Inceptisol, respectively. The average content of DTPA-extractable micronutrients was highest under soil order Entisol followed by Inceptisol and Aridisol. The content of micronutrients showed a declining trend with increase in soil depth in all orders. Among different soil properties, the pH and EC showed significantly negative correlation, however, OC had non-significant correlation with DTPA-extractable micronutrients in soils. Therefore, it is concluded that parent material, land use systems and soil depth affected the distribution of DTPA extractable micronutrients in different soil orders.

The Influence of Mineralogy and Cation Exchange Capacity toward Electrical Resistivity Value

Electrical Resistivity Tomography (ERT) is a method used for subsurface profiling in soil to characterize soil thickness, fracture zones, soil saturation, salinity and groundwater based on the electrical resistivity value (ERV). There are multiple factors that influence the electrical resistivity value, such as the porosity, degree of saturation, mineralogy, density, cation exchange capacity (CEC), and water resistivity. For this study, the effect of CEC towards resistivity value is studied via controlling the mineralogy factor, saturation, porosity and water resistivity. Thus, via understanding the CEC factor able to relate the resistivity and mineralogy of soil. This study is using a few common minerals in soil and rock, such as kaolinite, montmorillonite, illite, quartz, mica, and feldspar. The particle sizes of all tested minerals were passing 0.063mm sieve. The basic index properties of minerals such as particle size distribution, specific gravity, and Atterberg limit were tested. The instruments of Terrameter LS2 and resistivity box were used to determine the resistivity value of minerals. The Atomic Absorption Spectroscopy (AAS) machine was used to analyze the CEC of minerals via dilute with the ammonium acetate solution. The porosity and degree of saturation of minerals mixed with distill water were controlled between the range of 0.5 to 0.6 and 20% to 100%. The CEC of each mineral has different value, where the lowest and the highest minerals CEC in this study were Kaolinite and Montmorillonite at 1 and 70, respectively. The electrical resistivity values decrease with the increasing of CEC value and degree of saturation. The mineral that has higher CEC indicates lower resistivity value. Meanwhile, via increasing the degree of saturation of minerals were decrease its resistivity values.

Characterisation of clay mineralogy of the major soils in the Northern region of Sri Lanka

The Journal of the National Science Foundation of Sri Lanka publishes the results of research in all aspects of Science and Technology. The journal also has a website at http://www.nsf.gov.lk/. 2021 Impact Factor: 0.682The JNSF provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.

Increasing the Strength Properties in weak Soil Using Microbial Techniques

In Microbial-Induced Calcite Precipitation (MICP) has been introduced in the field of ground improvement. The applications of this method shows potential in several fields like improvement of strength and durability of concrete, bricks, sand permeability, soil strength etc., and various works are being conducted on these fields in the current scenario. To promote the engineering properties of the material after MICP treatment, need to have study the relevant crystal mineralization process and analyses the influences on the soil engineering properties. The main aim of this paper is to analyses the behavior of various bio geo chemical processes between the soil mineralogy, solid soil grains, water or fluid, and gases in the voids, beneath the soil surface after employing microbes as strengthening consultant. Geotechnical applications currently being inquired which includes the process of cementation of sands, to enhance bearing capacity and liquefaction resistance, Carbon sequestration, erosion control of soil, controlling the groundwater flow, and remediation of soil and groundwater impacted by metals and radio-nuclides.

Evaluation of using digital photography as a cost-effective tool for the rapid assessment of soil organic carbon at a regional scale

A rapid and cost-effective soil organic carbon (SOC) monitoring is vital for soil management. While SOC laboratory analysis is expensive and time-consuming, spectroscopic sensor technology allows for much faster and inexpensive acquisition of data. Still, the initial cost of spectroscopic sensors is high for farmers. With soil color as a proxy, digital cameras could be used as SOC sensors. We compared the performance of SOC prediction based on soil color on a regional scale. Soil color measurements were made on samples covering the German state of North Rhine-Westphalia. SOC ranged between 0.03 and 4.74%. Images of the samples were taken under standardized conditions with four different sensors. Various soil color space models and indices were derived for SOC prediction. Modeling was performed using multiple linear regression (MLR) and random forest (RF). Best SOC prediction results were achieved using color of wet soils. Best MLR and RF models gave similar validation R2 values for the prediction of SOC at 0.66 and 0.63 with RMSE values of 0.57 and 0.61%, respectively. The MLR models using one color space showed the same performance as the RF models using the full vis spectrum. This suggested that the vis spectrum does not contain more information than the three variables of a common color space. A smartphone had the same accuracy as a more professional camera, making it a potential soil sensor. With increasing scale, soil mineralogy influences soil color weakening the performance.

Soil Fertility and its Relationship to Soil Mineralogy of some Areas in Southwest Sinai, Egypt

Soil Fertility and its Relationship to Soil Mineralogy of some Areas in Southwest Sinai, Egypt

Clay mineralogy fingerprinting of loess-mantled soils on different underlying substrates in the south-western Poland

Loess may be integrated into slope deposits at different soil depths and may influence related physical, chemical and mineralogical soil properties. Therefore, tracking the border between deposited loess and underlying materials and estimating the depth of loess penetration is a challenge. Five soils from the Lower Silesia province in south-western Poland having different types of geologic substrate and being covered by loess deposits of various thicknesses were chosen to: 1) trace the origin of phyllosilicates in these heterogeneous soils (loess vs. underlying bedrock); 2) determine the influence of the geologic substrate and the loess mantle on clay mineral transformation in the soil; and 3) relate clay mineralogical traits to soil morphology. The loess consisted of long-distance and local aeolian sources as shown by the Ti/Zr ratios and heavy mineral composition. Geochemical and mineralogical traces of loess were easily detected in the mixed zone and in part also in the basal layer. The loess deposits are characterised by mica, chlorite, kaolinite, interstratified mica-vermiculite or hydroxy-interlayered vermiculite, vermiculite and a minor amount of smectite. Aeolian silt admixture was an important source of chlorite at all sites. The vertical distribution of mica indicated two types of sources — loess input and substrate. Smectite, however, has mostly been inherited from the underlying bedrock (serpentinite, glacio-fluvial deposits and basalt slope sediment) or was formed in the soils from mica or chlorite. Where present in the loess, smectite was only found in small amounts. The presence of kaolinite, HIV and mixed layered mica-vermiculite could be derived either from aeolian input or neoformation and thus actively occurring mineral (trans)formation reactions. Similar to mica, vermiculite was derived from both aeolian input and the geological substrate. The widespread loess deposits in this region rejuvenated the soil formation process, as evidenced by their mineralogical and chemical composition.

Soil carbon stocks in temperate grasslands differ strongly across sites but are insensitive to decade-long fertilization.

Enhancing soil carbon (C) storage has the potential to offset human-caused increases in atmospheric CO2 . Rising CO2 has occurred concurrently with increasing supply rates of biologically limiting nutrients such as nitrogen (N) and phosphorus (P). However, it is unclear how increased supplies of N and P will alter soil C sequestration, particularly in grasslands, which make up nearly a third of non-agricultural land worldwide. Here, we leverage a globally distributed nutrient addition experiment (the Nutrient Network) to examine how a decade of N and P fertilization (alone and in combination) influenced soil C and N stocks at nine grassland sites spanning the continental United States. We measured changes in bulk soil C and N stocks and in three soil C fractions (light and heavy particulate organic matter, and mineral-associated organic matter fractions). Nutrient amendment had variable effects on soil C and N pools that ranged from strongly positive to strongly negative, while soil C and N pool sizes varied by more than an order of magnitude across sites. Piecewise SEM clarified that small increases in plant C inputs with fertilization did not translate to greater soil C storage. Nevertheless, peak season aboveground plant biomass (but not root biomass or production) was strongly positively related to soil C storage at seven of the nine sites, and across all nine sites, soil C covaried with moisture index and soil mineralogy, regardless of fertilization. Overall, we show that site factors such as moisture index, plant productivity, soil texture, and mineralogy were key predictors of cross-site soil C, while nutrient amendment had weaker and site-specific effects on C sequestration. This suggests that prioritizing the protection of highly productive temperate grasslands is critical for reducing future greenhouse gas losses arising from land use change.

Rock weathering controls the potential for soil carbon storage at a continental scale

As rock-derived primary minerals weather to form soil, they create reactive, poorly crystalline minerals that bind and store organic carbon. By implication, the abundance of primary minerals in soil might influence the abundance of poorly crystalline minerals, and hence soil organic carbon storage. However, the link between primary mineral weathering, poorly crystalline minerals, and soil carbon has not been fully tested, particularly at large spatial scales. To close this knowledge gap, we designed a model that links primary mineral weathering rates to the geographic distribution of poorly crystalline minerals across the USA, and then used this model to evaluate the effect of rock weathering on soil organic carbon. We found that poorly crystalline minerals are most abundant and most strongly correlated with organic carbon in geographically limited zones that sustain enhanced weathering rates, where humid climate and abundant primary minerals co-occur. This finding confirms that rock weathering alters soil mineralogy to enhance soil organic carbon storage at continental scales, but also indicates that the influence of active weathering on soil carbon storage is limited by low weathering rates across vast areas.

Soil Carbon Dioxide Flux Partitioning in a Calcareous Watershed With Agricultural Impacts

AbstractPredicting the partitioning between aqueous and gaseous C across landscapes is difficult because many factors interact to control carbon dioxide (CO2) concentrations and removal as dissolved inorganic carbon (DIC). For example, carbonate minerals buffer soil pH and allow CO2 dissolution in porewaters, but nitrification of fertilizers may decrease pH so that carbonate weathering results in a gaseous CO2 efflux. Here, we investigate CO2 partitioning in an agricultural, first‐order, mixed‐lithology humid, temperate watershed. We quantified soil mineralogy and measured porewater chemistry, soil moisture, and soil pCO2 and pO2 as a function of depth at three hillslope positions. Variation of soil moisture along the hillslope was the dominant control on the concentration of soil CO2, but mineralogy acted as a secondary control on the partitioning of CO2 between gaseous and aqueous phases. Regression slopes of pCO2 versus pO2 in the carbonate‐bearing soils indicate a deficit of aerobically respired CO2 relative to O2 (p &lt; 0.05). Additionally, nitrification of upslope fertilizers did not lower soil pH and therefore did not cause a gaseous CO2 flux from carbonate weathering. We concluded that in the calcareous soils, up to 43% of respired C potentially dissolves and drains from the soil rather than diffusing out to the atmosphere. To explore the possible implications of the reactions we evaluated, we used databases of carbonate minerals and land uses to map types of soil degassing behaviors. Based on our maps, the partitioning of respired soil CO2 to the aqueous phase could be important in estimating ecosystem C budgets and models.

Dynamics of organic matter molecular composition under aerobic decomposition and their response to the nitrogen addition in grassland soils

Grassland soils store a substantial proportion of the global soil carbon (C) stock. The transformation of C in grassland soils with respect to chemical composition and persistence strongly regulate the predicted terrestrial-atmosphere C flux in global C biogeochemical cycling models. In addition, increasing atmospheric nitrogen (N) deposition alters C chemistry in grassland soils. However, there remains controversy about the importance of mineralogical versus biochemical preservation of soil C, as well as uncertainty regarding how grassland soil C chemistry responds to elevated N. This study used grassland soils with diverse soil organic matter (SOM) chemistries in an 8-month aerobic incubation experiment to evaluate whether the chemical composition of SOM converged across sites over time, and how SOM persistence responded to the N addition. This study demonstrates that over the course of incubation, the richness of labile compounds decreased in soils with less ferrihydrite content, whereas labile compounds were more persistent in ferrihydrite rich soils. In contrast, we found that the richness of more complex compounds increased over the incubation in most sites, independent of soil mineralogy. Moreover, we demonstrate the extent to which the diverse chemical composition of SOM converged among sites in response to microbial decomposition. N fertilization decreased soil respiration and inhibited the convergence of molecular composition across ecosystems by altering N demand for microbial metabolism and chemical interactions between minerals and organic molecules. This study provides original evidence that the decomposition and metabolism of labile organic molecules were largely regulated by soil mineralogy (physicochemical preservation), while the metabolism of more complex organic molecules was controlled by substrate complexity (biochemical preservation) independent to mineral-organic interactions. This study advanced our understanding of the dynamic biogeochemical cycling of C by unveiling that N addition dampened C respiration and diminished the convergence of SOM chemistry across diverse grassland ecosystems.

Mineralogy and genesis of soils developed from ultrabasic and alkaline rocks of Lages Alkaline Complex, Brazil

In the Plateau of Lages, intrusions of alkaline and ultrabasic rocks occur, rocks of rare occurrence in Brazil, whose soils derived from them are practically unknown. The study aimed to evaluate the chemical composition, mineralogy, genesis, and classification of the soils developed from the rocks Nepheline Sienite (P1), Volcanic Breccia (P2), Kimberlitic Breccia (P3), Phonolitic Tephrite (P4), and Phonolite (P5). After the morphological description (field) and the collection of soil samples, chemical analyses of the soils, mineralogical of the clay fraction and the total elements of the soils and the corresponding rocks that gave rise to them were carried out. Three Humudepts (Cambissolos), a Hapludolls (Chernossolo), and a Kandiudox (Nitossolo) were identified. Except for the P3 profile, the others are acidic soils, with high levels of exchangeable aluminum, poor in basic cations, with low sum and base saturation, showing a high degree of weathering and strong leaching. In the clay fraction, the presence of 2:1 clay minerals predominated with kaolinite with interlayered hydroxy-Al polymers. The P3 profile showed a slightly acidic reaction, high sum and base saturation, and practically zero exchangeable aluminum, a situation compatible with mineralogy, where trioctahedral vermiculite predominated, revealing that it was a young, slightly weathered soil.