Soil In Area Research Articles

Load transfer mechanism of floating pile-supported embankments under cyclic loading

Pile-supported embankments are one of the most commonly used techniques for ground improvement in soft soil areas. Existing studies have mainly focused on embankments supported by end-bearing piles under static loading, with limited research on floating pile-supported embankments under cyclic traffic loading. In this study, model tests for unreinforced floating, unreinforced end-bearing, geosynthetic reinforced floating, and geosynthetic reinforced end-bearing pile-supported embankments were conducted. Cyclic traffic loading was simulated using a three-stage semi-sinusoidal cyclic loading. Comparative analyses and discussions are performed under floating and end-bearing conditions to investigate the influence of floating piles on the soil arching evolution and membrane effect under cyclic loading. The results indicate that floating piles result in earlier stabilization of surface settlement. There is less arching and membrane effect induced by floating piles, and the arching does not continue to degrade under cyclic loading. Less membrane effect in floating pile-supported embankments results in less geosynthetic and pile strain. The degree of membrane effect in floating pile-supported embankment largely depends on the pile-end condition.

Study on Evaluation and Prediction Model of Long-term Mechanical Properties of Fine-grained Saline Soil Subgrade

In this thorough examination, we dive deep into the long-lasting mechanical characteristics of fine-grained saline soil subgrades, aspiring to establish a precise and reliable collection of predictive models. Our objective is to provide a solid scientific footing for the design and ongoing upkeep of road networks within saline soil environments. Analyzing prolonged monitoring data across diverse highway subgrades within a prototypical saline soil locale, we unveil the intricate temporal fluctuations and environmental sensitivities of the soil’s mechanical properties under continuous load. Precisely, the subgrade’s compressive modulus dwindled by 15%, while shear strength declined by 8% over a five-year period. These trends intensify during rainy and scorching seasons, with drops surpassing 20% and 12% respectively. Leveraging this intricate data, we deploy nonlinear regression analysis and sophisticated machine learning algorithms to construct a predictive model tailored for the long-term mechanical properties of fine-grained saline soil roadbeds. This model integrates a multitude of factors, including load duration, temperature, humidity, and more, delivering accurate forecasts of key subgrade indicators like compressive modulus, shear strength, and beyond. In the verification stage, compared with the measured data, the error rate of the model prediction results is controlled within 5%, showing high prediction accuracy and stability. In addition, we also carried on the sensitivity analysis to the model, found that the load size and the duration of the impact on the mechanical properties of the roadbed is the most significant. Therefore, in the design of road engineering in saline soil areas, the influence of these factors should be fully considered, and reasonable engineering measures should be taken to ensure the safety and durability of roads. This study not only provides effective data support for the long-term mechanical performance evaluation of fine-grained saline soil roadbed, but also provides an important theoretical reference for engineering practice in related fields.

Litter Chemistry Is a Main Driver of Inorganic Nitrogen in Disturbed Soils in the Arid Patagonian Monte

ABSTRACTChanges in plant cover and soil characteristics induced by grazing may affect litter quality and nitrogen (N) release under varying abiotic conditions. Our study was focused on the importance of litter chemistry as a main driver of inorganic N (ammonium‐N: NH4+‐N and nitrate‐N: NO3−‐N) release to soil. Both inorganic N forms are important components for N availability to plants and soil processes, and the long‐term conservation of soil‐N fertility. We analyzed the effect of secondary compounds and the C/N ratio in litter under varying soil water, and UV exposure on soil inorganic N (NH4+‐N and NO3−‐N) in Patagonian Monte degraded soils. We hypothesized that secondary compounds and C/N ratio in litter are main drivers of soil inorganic N under varying abiotic conditions. We conducted a microcosm experiment (13 months) using intact upper soil blocks from denuded soil areas. Surface soils were added with shrub (SL), and mixed grass and shrub (GSL) litter with high versus low secondary metabolites concentration and low vs. high C/N ratio, respectively. Microcosms were maintained under ambient and reduced UV exposure, and high and low soil water. We used microcosms without litter as controls. Monthly, we assessed NH4+‐N and NO3−‐N concentrations in upper and sub‐superficial soils. Litter chemistry interacting with abiotic factors did not significantly influence soil NH4+‐N at any soil depth while litter chemistry was a main driver of NO3−‐N in upper soil. SL enhanced NO3−‐N in upper soil compared with GSL independently of abiotic factors. In upper soils without litter and in those with GSL, the highest NO3−‐N concentration occurred mostly under high soil water and exposition to UV. We concluded that litter chemistry was a main driver of soil N fertility in disturbed rangelands. Shrub litter may enhance N fertility (NO3−‐N) in degraded soils.

Optimizing Nitrogen Input Increased Yield and Efficiency in Maize-Soybean Strip Intercropping System

Optimizing nitrogen (N) fertilizer combination is a crucial measure to maximize yield and production efficiency in a maize-soybean strip intercropping system (MSSI). In this field experiment, six maize/soybean N input combinations (0 kg ha−1, F0; 255/30 kg ha−1, F1; 255/45 kg ha−1, F2; 255/60 kg ha−1, F3; 210/45 kg ha−1, F4; 300/45 kg ha−1, F5) were set in 2022 and 2023. The results indicated that optimizing N combination (maize/soybean, 255/45 kg ha−1) could synergistically increase yield and economic benefits. Path analysis results showed that the grain numbers in maize and soybean emerged as the most critical yield-affecting factors. Compared with F0, F5 showed the highest grain yield during the 2-year experiment, and the net return increased by 86.1% (F1), 133.3% (F2), 87.4% (F3), 104.7% (F4), and 128.3% (F5), respectively. Optimizing N input under F2 and F5 notably enhanced the leaf area index (LAI) of maize at the milk stage (R3) and soybean at the full pod stage (R4). Additionally, optimization of N distribution in maize stems at the tassel stage (VT) and soybean leaves at the initial flowering stage (R1) facilitated increased dry matter and N accumulation at the maturity stage, resulting in final land equivalent ratios (LER) of 1.44 and 1.55, respectively. Our results provide a more valuable field N combination for summer maize planting areas (sandy soil areas) in Huang-Huai-Hai and southern China, thus promoting the wider application of MSSI.

Database Analysis of Long-Term Settlement Behavior of Pile Foundations in Shanghai Soft Coastal Clays

A database of 195 field records of long-term settlement of high-rise buildings in Shanghai soft coastal clays is presented. The collected field records are divided into two categories based on pile type, i.e., bored pile and precast pile. Based on the settlement recorders collected, the long-term settlement behavior and settlement duration of the pile foundations in soft coastal clays are investigated. The statistical results show that the pile foundation in Shanghai soft coastal clays can be divided into three kinds of site conditions by considering the pile length and variation of long-term deformation behavior. Prediction models based on the power function are proposed to calculate the normalized final settlement for both bored pile and precast pile foundations. Based on the statistical results, the average normalized final settlement (settlement per floor), average settlement ratio (final settlement to the settlement when the superstructure is completed), and average settlement duration in the three site conditions for both bored pile and precast pile foundations are given. Additionally, an exponential settlement prediction model that can accurately forecast the entire settlement and post-construction settlement characteristics of buildings in Shanghai’s soft soil area is proposed. These statistical results can be referred to the preliminary foundation design works, which contribute to the quick evaluation of the possible settlement range, settlement ratio, and settlement duration of the proposed building constructed in the soft coastal clay area in Shanghai.

Plant growth promoting bacteria promote rice growth cultivated in two different sandy soils subjected distinct climates conditions.

Sandy soils contain around 70% sand in their composition, making them highly fragile and susceptible to land degradation. Practices such as no-tillage cultivation, the use of bioinoculants, and the application of organic amendments can restore the organic matter in these soils, ensuring sustainable production. In this context, this work aimed to study the microbiological aspects of two sandy soil areas (Brazilian Northeast and South) under contrasting climatic conditions (tropical and temperate). With this purpose, prokaryotic communities were evaluated, and the plant growth-promoting potential of isolated bacteria was assessed by rice inoculation in sandy soil. Despite the high sand content in both soils, soil from the NE was related to the highest phosphorous, calcium, potassium, copper, sodium, zinc, magnesium, and manganese contents, organic matter percentage, and pH. The Shannon diversity index indicated that prokaryotic communities in NE were more diverse than in SU, and PCA revealed that microbial composition exhibited distinct patterns. The rice inoculation experiments were executed to verify if the bacterial isolates displayed a similar growth promotion potential when inoculated in sandy soil areas subjected to different climatic conditions. When all PGP characteristics evaluated were pooled in a PCA, a similar pattern was observed for SU and NE. Burkholderia sp. SU94 was related to highest PGP characteristics evaluated. Paraburkholderia sp. NE32 showed similar results to those of the non-inoculated control. This similar effect of rice growth in the Northeast and South of Brazil suggests that isolate SU94 adapts to different environmental conditions.

Potentially hazardous elements in atmospheric precipitation during the warm season (May–September) of 2019 in Moscow

Atmospheric precipitation acts as a significant pathway for pollutants from the atmosphere to the Earth’s surface, and analyzing urban precipitation data on intensity, fallout regime, transfer patterns, and solid particle content helps identify pollution sources. For the first time in the Moscow megacity, the levels of soluble forms of potentially hazardous elements (PHEs) in atmospheric precipitation were studied during the whole summer season of May–September 2019. The concentrations of Al, As, B, Ba, Be, Bi, Cd, Ce, Co, Cu, Fe, La, Li, Mn, Ni, P, Pb, Rb, Sb, Sn, Sr, and Zn were determined using inductively coupled plasma mass spectrometry and atomic emission spectroscopy methods. The research underscores the crucial role of atmospheric precipitation in washing PHEs out of the atmosphere. In May and September, concentrations of PHEs surpass the warm-season average. Notable contamination in May stems from elevated traffic during vacations, extensive burning of plant debris and wood, and pollen transport. Summer months are characterized by reduced forest and agricultural fires, traffic, and increased vegetation, leading to lower PHE concentrations, especially in July, with typical amount of precipitation contributing to pollutant dispersion. Elevated PHE levels in September are observed due to increased traffic load, biomass burning, and the expansion of unvegetated soil areas. Rainwater is enriched with Sb, Pb, Cd, Zn, Cu, B, Bi, P, and Sr, sourced from vehicle emissions, soil particles, industry, construction dust, biomass burning, and forest fires. Moderate enrichment with Ba, Mn, Ni, Co, and Sn also occurs episodically. Regression analysis highlights solid particles’ role as a major PHE source in rainwater, with the longer antecedent dry periods and the higher acidity level of rain intensifying the accumulation of PHEs. Long-range transport plays a lesser role, with Southern and Northern Europe, Western Siberia, and the central part of European Russia contributing meaningfully.

Evaluation of Soils Around the Crude Oil Desalting Plant by MCDM Method to Reduce Pollution in the Koreyt Camp Area of Ahvaz, Iran

ABSTRACT In order to identify the factors causing environmental pollution caused by petroleum industries in Ahvaz County, Khuzestan province, regarding local concerns, the area of soil affected by the operational activity of crude oil desalting plantation (CODP) should be determined. In addition, in order to identify obvious environmental risks leading to soil pollution, it is necessary to identify hazardous activities ‎(HA). MCDM methods, or multi-criteria decision-making models, for ranking options, and choosing the best option for identifying environmental risks. Therefore, in this research, by examining models of multi-criteria decision-making, including the AHP Analytical Hierarchy Process and the TOPSIS Model (Technique for Order of Preference by Similarity to Ideal Solution), HAs for determining the possibilities of contamination have been discussed. HAs are considered to determine the possibility of contamination. According to the results, the transfer of saline oil from the exploitation unit to the CODP, with a specific ‎vector weight of 0.214 in the AHP method and a proximity coefficient of 0.445 in the ‎TOPSIS method, gain highest rank in terms of HAs in the study area. Regarding the risk assessment and assurance of the creation of salinity and sometimes petroleum pollutants in the region, and also the local obligations and regulations of the founders, industrial devices should preferably use biological methods to remediate and naturalize the environment. According to the results, and regarding the fact that halophyte can grow and develop well in the saline conditions; halophyte culture (haloculture technique) can be used as a method for soil bioremediation.

Experimental Study on Water and Salt Migration and the Aggregate Insulating Effect in Coarse-Grained Saline Soil Subgrade under Freeze–Thaw Cycles

Understanding multiphase transformations and the migration of heat, water, vapor, and salt in coarse-grained saline soil under groundwater recharge and environmental freeze—thaw cycles is crucial for ensuring the stability of highway infrastructures. To clarify the water, heat, vapor, and salt migration patterns in coarse-grained saline soil, as well as the salt-insulating effect of the aggregate insulating layer, an experimental study was conducted in a soil column model under pressureless water replenishment with fluorescein-labeled liquid water under freeze—thaw cycles. The results showed that the temperature in the saline soil columns periodically changed and that hysteresis effects occurred during temperature transfer. External water replenishment and the content of liquid water inside the soil exhibited nonlinear changes with environmental temperatures. After multiple freeze—thaw cycles, two water and salt accumulation zones formed within the coarse-grained saline soil subgrade. The migration of liquid water resulted in a water and salt accumulation zone in the nonfrozen zone, whereas the migration of water vapor yielded a water and salt accumulation zone in the frozen zone. To prevent water and salt migration, a 20 cm thick gravel insulating layer could be laid at a distance of 10 cm from the bottom of the roadbed, which could provide a satisfactory salt-insulating effect. The research results provide a theoretical basis and guidance for regulating the stability of subgrades in saline soil areas.

Investigation on the Bearing Performance of a Single Pile in Shallow Reinforced Soft Soil Foundation under Horizontal Load

The overall reinforcement of soft soil foundation has the disadvantages of large engineering quantity and high cost. When the pile foundation bears horizontal loads in the soil, the mechanical properties of the soil near the surface have a greater impact on it compared to the deep soil. Therefore, studying the influence of shallow soil reinforcement on the horizontal bearing capacity of pile foundations has important engineering significance. Studying the influence of shallow soft soil reinforcement around piles on the horizontal bearing performance of piles is of great significance for improving the economic efficiency of pile foundation reinforcement technology in soft soil areas. In this paper, seven pile-soil finite element models are established based on ABAQUS 2022 software to study the influence of shallow reinforcement on the horizontal bearing capacity of single pile. The models were established on the basis of a field test and its validity was verified. The influence of different reinforcement degrees on the horizontal bearing capacity of piles is analyzed by taking the reinforcement width and reinforcement depth as variables. The results indicate that shallow ground improvement significantly enhances the horizontal bearing capacity of the pile. The horizontal bearing capacity of the pile is increased by 83.0%, 104.3%, and 224.4%, respectively, corresponding to a reinforcement width of 2 times, 3 times, and 4 times the diameter of the pile, respectively. With the increase of the reinforcement width, the bending moment and deformation of the pile under the same horizontal load decrease significantly, while it has no significant effect on the location of the maximum bending moment of the pile. The bearing capacity of the pile foundation gradually increases with the increase of the reinforcement depth. Compared with the unreinforced situation, the horizontal bearing capacity of the pile body is increased by 224.4%, 361.3%, and 456.8%, respectively, corresponding to a reinforcement depth of 0.1 times, 0.2 times, and 0.3 times the pile length. As the reinforcement depth increases, the corresponding increase in bearing capacity does not increase linearly, but gradually decreases. This indicates that blindly carrying out deep soil reinforcement without comprehensive evaluation is not advisable.

Influence of soil organic carbon fractions on the soil priming effect under different vegetation restoration modes

AbstractThe soil priming effect is a key mechanism influencing carbon (C) cycling processes between the forest soil organic carbon (SOC) pool and the atmosphere. Different vegetation restoration modes have different SOC pool compositions, and it is not clear whether such differences affect the soil priming effect. Therefore, we selected soil from six typical vegetation restoration modes Platycladus orientalis (PO), Pinus sylvestris (PS), Quercus acutissima (QA), shrub (SH) and wasteland (WL) in the soil and rocky mountainous areas of northern China and measured the soil properties, microbial communities, microbial necromass carbon (MNC), SOC fractions and the soil priming effect. The SOC content decreased in the order of PO (21.33 g kg−1), PS (22.00 g kg−1), QA (13.67 g kg−1), SH (13.33 g kg−1) and WL (10.33 g kg−1), and the trends of the mineral‐associated organic carbon (MAOC) and fungal necromass carbon (FNC) content were the same as those of the SOC content. The soil priming effect was greater in both forests and shrublands than in wastelands, with the greatest effect occurring in PO forests, where the soil priming effect reached 159.91 mg CO2‐C kg−1 soil after 30 days of incubation, which was 1.4 times greater than that in WL. The soil priming effect was mainly determined by the difference in MAOC content. In addition, the soil C/N ratio and bacterial community diversity also indirectly affected the soil priming effect by influencing the soil MNC and SOC fractions. Overall, afforestation increased the SOC content, fungal necromass contribution and mineral conservation, increasing the soil priming effect. This theoretical foundation supports the enhancement of SOC sequestration capacity by implementing various modes of vegetation restoration in the future.

Vertical migration flux of soil carbon and nitrogen of sloping farmland in <?A3B2 pi6?>typical black soil areas

Vertical migration flux of soil carbon and nitrogen of sloping farmland in <?A3B2 pi6?>typical black soil areas

Sustainable stabilization/solidification of Cu-contaminated seasonal frozen soil by epoxy resin: environmental risk assessment and engineering applicability

There are significantly toxic Cu contaminants in seasonal frozen soil areas under industrial production and mineral exploitation. However, the hydration reactions of mainstream alkaline curing agents such as cement are disturbed by the solidification and thawing of moisture, and their solidification/stabilization is ineffective to heavy metals. Therefore, there is an urgent requirement to optimize the use of current curing agents to improve the solidification/stabilization (S/S) effect of Cu contaminants in seasonal frozen soil areas. In this study, the Epoxy resin (EP) with excellent waterproofing and frost resistance was incorporated into artificially prepared Cu-contaminated soil to maintain a steady engineering application strength and inhibit the outward diffusion of toxic Cu contaminants under freeze-thaw cycles. The freeze-thaw resistance of EP-cured Cu-contaminated soil and the feasibility of EP remediation technology have been investigated, including mechanical properties, environmental effects and microstructure. The decline in mechanical strength and the increment in Cu leaching during freeze-thaw cycles are effectively suppressed by the remediation of EP. Even after 8 freeze-thaw cycles, there is merely a mechanical strength decline of 5%, solely a secondary Cu leaching of 4.74mg/L, and astonishingly a leachable index of 11.70 in the specimens with 12% EP dosage. The expansion phenomenon of pores and clay fractures under freeze-thaw cycles were gradually alleviated after incorporation of EP. The above results demonstrate the Cu-contaminated seasonal frozen soil remedied by EP are high-strength, basically non-toxic, and environmentally friendly material which are suitable for in-situ stabilization/solidification in seasonal frozen soil areas.

A Novel Bare Soil Index for Enhancing the Mapping of Bare Soil Area – An Indicator of Urban Expansion

A Novel Bare Soil Index for Enhancing the Mapping of Bare Soil Area – An Indicator of Urban Expansion

Spatial pattern and compositional distribution of organochlorine pesticides in the black soil region of Shenyang

Organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) prevalent in soils with carcinogenic, teratogenic and mutagenic hazards that are commonly found in soils and remain in the environment even though they have been banned. In order to fill the gap of fewer studies after the ban, soil samples were collected from 308 agricultural fields of cash crops and grain crops in the black soil area of Shenyang City (Liaozhong District, Faku County, Xinmin City and Kangping County) in this study. The aim was to determine, the use and distribution characteristics of OCPs in agricultural soils in the black soil region of Shenyang City. Compositional analysis showed that the detection rate of banned OCPs in agricultural soils was 71.75%, including contaminants such as technical dichloro-diphenyl-trichloroethane (DDT), chlordane and hexachlorobenzene (HCB), which were widely distributed in Liaozhong District, Faku County, Xinmin City and Kangping County, with 45.25% of the fields having compounded contamination of OCPs, and several areas were involved in the fresh inputs of contaminants such as technical DDT. Among them, Kangping County and Faku County are more seriously polluted, with 66.29% and 60.71% of OCPs exceeding the standard. Soil OCPs is more serious in cabbage and rice farmland among cash and food crop farmland. Based on Chinese policy on control, prevention and other pesticide management measures, it was concluded that the framework should be strengthened to prevent further illegal use of banned OCPs.

Study on settlement deformation law of new and old subgrade of expressway reconstruction and expansion based on CPTU

In the reconstruction and expansion of expressways in soft soil areas, controlling the differential settlement between the new and existing subgrades is of vital importance. To investigate the settlement and deformation characteristics of both the new and existing subgrades, piezocone penetration test (CPTU) and dissipation tests were conducted on these subgrades. The CPTU dissipation data was utilized to determine the soil’s degree of consolidation, and settlement calculations for the new and existing road subgrades were based on the CPTU test results. Subsequently, a finite element model was developed using the CPTU test findings to analyze the horizontal displacements, vertical settlements, and differential settlements of the new and existing subgrades before and after the reconstruction and expansion. Based on the measured settlement results, the new and old subgrade settlement calculation results are verified. The outcomes revealed that the degree of consolidation for the existing road subgrade of the Lianhuai Expressway ranged between 42 % and 96 %. The maximum horizontal displacement of the subgrade pre- and post-expansion occurred at the slope toe. Before expansion, the maximum vertical settlement was observed along the road’s centerline, while after expansion, it was located in the centerline of the widened section. The maximum additional settlement amounted to 274.77 mm. During the new road construction phase, the differential settlement between the new and existing road subgrades increased rapidly over time, peaking at its maximum value. However, during the operational phase of the new road, this differential settlement tapered off as time progressed.

Impact of Crude Oil Pollution on some Geotechnical Characteristics of North Rumaila Soils in the Southern Iraqi Province of Basrah Governorate

Background: Pollution affects the soil and results in a change in its natural, chemical, or organic characteristics and properties, which directly or indirectly affect the geotechnical properties of the soil and make it unsuitable for engineering use. The aim of the study is to determine how adding various amounts of crude oil to the study area's soil affects the soil's geotechnical characteristics, including soil shear resistance, compaction coefficients, and California bearing capacity. Materials and Methods: The North Rumaila site was chosen for the study. At a depth of one meter, natural, pollution-free soil was extracted, and weight percentages of 2%, 4%, 6%, 8%, and 10% of crude oil were added. Grain size analysis, moisture content, direct shear, compaction, and Californian bearing tests were conducted. Results: The findings indicate that the soil at the North Rumaila site has a moisture content of 6.45% and is mostly silty sand with small amounts of clay and gravel. Crude oil was added to the soil, which caused the Californian to lose some of its bearing capacity, the optimal moisture content to raise, the angle of internal friction to decrease, and the bearing capacity of the soil to decrease. Conclusion: Pollution by crude oil effects negatively impacted the soil's geotechnical qualities.

Map of anthropogenic soil disturbance in Russia

Soils play an important role in maintaining the sustainability of the biosphere, as well as providing food, clothing and the basis for human life on Earth. In the process of irrational land use, soils are often degraded and sometimes completely destroyed. But, inventory of destroyed soils on a systematic basis is still not conducted in any country of the world. In Russia, traditional soil maps do not reflect the destroyed soils either. We have made an attempt to create the first map of the country, which shows soils destroyed as a result of directed anthropogenic impact. The map shows areas where soil cover was destroyed as a result of construction of buildings, structures, roads and railroads, quarries and embankments during mining. The crowdsourcing database OpenStreetMap was used as the main source of information, as well as the results of visual interpretation of disturbed soils using GoogleEarthTM satellite data. The data on disturbed soils were aggregated to soil-geographical sections of the Unified State Register of Soil Resources of Russia (scale 1 : 2500000) (UGRSR). The map is presented in GIS format (shapefile). The map contains information on the area and share of disturbed soils, as well as the type of impact that resulted in disturbance.

Attenuation Law of Performance of Concrete Anti-Corrosion Coating under Long-Term Salt Corrosion

In saline soil areas, the concrete piers of concrete bridges experience long-term corrosion, mainly caused by chloride salts due to alternating temperature changes. Waterborne concrete coatings are prone to failure in this aggressive salt environment. Implementing coating protection measures can improve the durability of concrete and enhance the service life of bridges. However, the effectiveness and longevity of coatings need further research. In this paper, three types of waterborne concrete anti-corrosion coatings were applied to analyze the macro and micro surface morphology under wet–dry cycles and long-term immersion conditions. Various indicators such as glossiness, color difference, and adhesion of the coatings were tested during different cyclic periods. The chloride ion distribution characteristics of the buried concrete coatings in saline soil, the macro morphology analysis of chloride ion distribution regions, and the micro morphology changes of the coatings under different corrosion times were also investigated. The results showed that waterborne epoxy coatings (ES), waterborne fluorocarbon coatings (FS), and waterborne acrylic coatings (AS) all gradually failed under long-term salt exposure, with increasing coating porosity, loss of internal fillers, and delamination. The chloride ion content inside the concrete decreased with increasing depth at the same corrosion time, while the chloride ion content at the same depth increased with time. The chloride ion distribution boundary in the cross-section of concrete with coating protection was not significant, while the chloride ion distribution boundary in the cross-section of untreated concrete gradually contracted towards the concrete core with increasing corrosion time. During the corrosion process in saline soil, the coatings underwent three stages: adherence of small saline soil particles, continuous increase in adhered material area, and multiple layers of uneven coverage by saline soil. The failure process of the coatings still required erosive ions to infiltrate the surface through micropores. The predicted lifespans of FS, ES, and AS coatings, obtained through weighted methods, were 2.45 years, 2.48 years, and 2.74 years, respectively, which were close to the actual lifespans observed in salt environments. The developed formulas effectively reflect the corrosion patterns of different resin-based coatings under salt exposure, providing a basis for accurately assessing the corrosion behavior and protective effectiveness of concrete under actual environmental factors.

CHARACTERIZATION AND CLASSIFICATION OF SOILS DEVELOPED ON COASTAL PLAIN SOILS FOR CROP PRODUCTION IN ORON LGA, SOUTH- SOUTH, NIGERIA

Soils are characterized and classified based on its unique properties. Detailed characterization of four representative areas of Oron coastal plain soils in South –South, Nigeria was carried out. Soil samples were collected from pedogenic horizons of soils in four sampling sites. Routine analysis of soil properties was carried out in the laboratory with standard laboratory procedures. Soil data was subjected to descriptive statistics using statistical analytical system. The soils have a deep well drafted profile of about deep 200 cm. The soil texture varied in areas ranging from loamy sand to sandy loam, sandy and sandy clay loam while bulk density increased down the natural horizons. The pH varied between moderately acidic to strongly acidic in the soils of the study area. The morphology of soils ranged in various colour matrix of hues (10-7.5) and Chroma values (1-8) in all horizons. The soils were characterized by Dark Brown (10YR3/3), Dark Greyish Brown (10YR4/2) and Yellowish Brown (10YR 5/4) to Grey (7.5YR6/2). The soils had low concentrations of exchangeable cations (Ca, Mg, Na and K). The Coefficient of variation (CV%) values ranged from 0.74 to 91.6 in Ca, Mg, Na and K. All the parameters in the soils of the study area showed low and medium mean values except soils of Esin Ufot1 and 2 which showed high mean values of Na with Esin Ufot 2 having the highest mean value of sodium to be 0.18 Cmol/kg. Suborder soils were classified as Grossarenic Kandiaqualfs (CEC > 16 Cmol/kg) for Esin Ufot1.Esin Ufot2, Esuk Oron1 while Esuk Oron 2 were classified as Typic Kandaquults (CEC < 16 Cmol/kg). A great importance in providing adequate data to enable right decision taking in the choice of site for developmental projects and crop production.