Soil Characteristics Research Articles

Description of representative “in-situ” soil profiles in northwestern Tunisia

Soil profiling is important for understanding soil evolution in space and time and its ability to deliver ecosystem services. It reflects the soil's physical, chemical, and biological, along with its management history. As a fundamental step in assessing soil health, it helps determine the soil’s potential for the provision of ecosystem services and its suitability for various agricultural and land-use applications. Soil profiling allows for the classification of soil types across different regions, contributing to soil mapping and enabling informed decisions for sustainable soil and land management. This study describes and classifies four soil profiles in Tunisia using the WRB classification system. The main areas of the WRB soil classification are soil Reference Soil Groups (RSG) mainly defined by diagnostic horizons, and qualifiers used to provide additional information about the soil's characteristics. The four soil profiles analyzed are Luvisol, Cambisol, Vertisol, and Fluvisol each exhibiting distinct physical, chemical, and morphological properties. Luvisol in Cap Negro (northern coast) is moderately fertile but vulnerable to erosion, necessitating protection measures. Cambisol in Oued Zarga (northern continental area) supports field crops but faces threats such as soil compaction and erosion, which can be mitigated by reduced tillage and providing soil cover after the harvest. Vertisol in Béja (northern continental area), characterized by high clay shrink-swell activity, is cultivated with winter cereals, where appropriate tillage and irrigation practices help manage soil stability. Lastly, Fluvisol in Oued Meliz (north-western continental area) benefits from high fertility due to alluvial deposits but requires careful water management to erosion. By providing detailed soil classification and management insights, this study contributes to deepen our understanding on soil classification, sustainable land use planning in Tunisia.

Field Inoculation of Pleurotus tuoliensis in Natural Habitat Promotes Microbial Communities That Enhance Its Growth

Pleurotus tuoliensis is a valuable edible mushroom native to Xinjiang in northwest China. It colonizes the roots and stems of Ferula plants. Field inoculation in its natural habitat has been shown to significantly enhance the colonization rate of P. tuoliensis hyphae in Ferula plants. However, the effects of field inoculation on P. tuoliensis hyphal colonization, soil properties, and microbial communities remain underexplored. In this study, we examined the characteristics of rhizosphere soil and microbial communities under four conditions: natural environments with and without hyphal colonization, and field inoculation with and without colonization. High-throughput sequencing results revealed that field inoculation markedly increased the relative abundance of Pleurotus species (57.98%) compared to natural colonization (14.11%). However, field inoculation also resulted in a reduction in microbial community diversity compared to hyphal colonization. Concurrently, the relative abundance of Pseudomonadota, Bacteroidota, and Bacillota significantly increased following field inoculation. LEfSe analysis suggested that the identified potential biomarkers were most likely associated with the Bacillus genus within Bacillota. Furthermore, mushroom growth-promoting bacteria were successfully isolated and identified as members of the Bacillus cereus group (L5) and Bacillus safensis (S16). This finding suggests that field inoculation with P. tuoliensis in its natural habitat promotes microbial communities that enhance its growth. This study offers new insights into conserving wild edible fungi and their interactions with soil microbiota.

Smart AG – Smart Agriculture using Gen AI

This project leverages generative AI to revolutionize agricultural practices by integrating advanced data analysis, predictive modeling, and real-time monitoring systems. By analyzing soil characteristics such as pH, moisture content, nutrient levels, and texture, the AI system provides farmers with precise crop recommendations tailored to specific soil conditions, ensuring optimal growth and yield. The system also considers environmental factors like temperature, humidity, and sunlight exposure to further refine crop suggestions. This enables farmers to plan their activities, such as planting, irrigation, and harvesting, more effectively, mitigating the impact of adverse weather conditions. Additionally, the system employs image analysis to detect potential crop diseases early by comparing images of crops with a comprehensive database of known diseases. This early diagnosis facilitates timely interventions, reducing crop losses and ensuring healthy produce. By offering accurate recommendations and predictions, the system helps farmers achieve higher yields and better-quality produce, ensuring a stable food supply and addressing issues of food security. The promotion of sustainable agricultural practices reduces the environmental impact of farming and ensures the long-term viability of agricultural activities. Additionally, the improved productivity and reduced losses lead to higher profits for farmers, contributing to economic growth in the agricultural sector.

Increasing the Proportion of Broadleaf Species in Mixed Conifer-Broadleaf Forests Improves Understory Plant Composition and Promotes Soil Carbon Fixation

Understory vegetation is an important component of forest ecosystems, and the supply of nutrients in the soil is related to the growth and development of soil microorganisms and understory plants. The effects of different tree species composition ratios in the forest on the process of soil microbial community assembly are not clear in the existing studies, and the factors influencing the differences in the abundance of understory plants under different forest canopy compositions and their mechanisms of action have not yet been clearly explained. In this study, two types of pure forests (PFP and PFQ) and two types of mixed forests (MF and MPQ) were selected from the Zhongcun Forestry, and the soil characteristics, soil microbial community assembly process, and understory plant community abundance, composition, and β-diversity were analyzed for the different forest types. The results showed that changes in the proportion of broadleaf and coniferous species in the forest could lead to changes in the community assembly process of soil fungi, and that the fungal assembly process in the mixed forest was mainly related to dispersal limitation. Compared with pure forests that were exclusively coniferous or exclusively broadleaf, mixed coniferous and broadleaf forests had a higher abundance of understory plants and a more stable forest community composition. In mixed forests, forests with a large proportion of broadleaf arbors had more available resources in the soil, soil pH was closer to neutral, and soil C was less likely to be lost compared to forests with a large proportion of conifers.

Performance evaluation of different soil infiltration models under the long-term conservation agriculture based management practices

Aim: This study aimed to assess the long-term impacts of various conservation agriculture practices on the infiltration characteristics of soil and to evaluate effectiveness of Kostiakov, Green and Ampt, and Philip models in predicting the infiltration rates. Methodology: The treatments examined included the permanent broad bed (PBB), PBB with residue (PBB+R), permanent narrow bed (PNB), PNB with residue (PNB+R), zero tillage (ZT), and ZT with residue (ZT+R) and conventional tillage (CT). Infiltration models were fitted to the experimental data and performance of each model was evaluated using statistical criteria. Results: Initial infiltration rate was maximum in PBB+R, which was 111.5% higher than in conventional tillage CT (lowest). Cumulative infiltration across all the treatments followed in the order of: PBB+R had the highest, followed by PNB+R>ZT+R>PBB>PNB>ZT>CT. The CA– based management practices showed 31.4– 85.2% higher observed steady state infiltration rate than CT. The model derived parameters like “a” value of Kostiakov, “ic” of Green and Ampt and “S” of Philip were higher under PBB+R than CT by 138.6, 154.3 and 112.1%, respectively. Kostiakov model performed the best for predicting infiltration rates with the highest R2≥0.92 and the lowest errors (RMSE≤1.26 cm hr–1, ARE≤0.76 cm hr–1 and MAE≤0.96 cm hr–1). Interpretation: Therefore, it was proventhat the empirical Kostiakov model could effectively represent the infiltration process in soil. Key words: Conventional tillage, Infiltration models, Kostiakov model, Permanent broad bed, Residue

Aluminum accumulation in mosses from the Brazilian savanna: a comparative study of two species revealing similar traits to vascular plants.

Mosses from the Brazilian savanna accumulate aluminum (Al) and exhibit mechanisms similar to vascular plants, but different species use distinct strategies for Al accumulation in apoplast and symplast pathways. Bryophytes are conspicuous components of the vegetation in the Brazilian savanna, particularly in the Campo Rupestre phytophysiognomy. There are two main types of Campos Rupestres, each with distinct soil characteristics: quartzitic and ferruginous. Quartzite soils are typically acidic and nutrient-poor, while ferruginous soils are rich in iron and tend to be acidic and low in nutrients. Despite these distinctions, these ecosystems share high soil aluminum (Al) content and vegetation with many Al-tolerant vascular plant species. However, the relationship between Al and bryophytes remains unexplored. We found that Campylopus lamellatus Mont. (Dicranaceae) and Polytrichum juniperinum Hedw. (Polytrichaceae) accumulate Al, despite the differences in the histolocalization within the gametophyte. C. lamellatus tends to accumulate Al apoplastically in the cell walls, whereas P. juniperinum accumulates it symplastically, potentially in vacuoles and chloroplasts. Additionally, populations of the same moss species in different studied sites of Campos Rupestres exhibited a similar pattern of accumulation, as our data indicated the pH and Al content of the soils were comparable. Our study provides the first evidence of Al accumulation in mosses from the Brazilian savanna, highlighting the potential for bryophytes to adapt to high-aluminum environments similarly to vascular plants.

Influence of NaCl Concentration on Compression Characteristics of Marine Soil and Micro-Mechanism Analysis

The salt concentration of the pore solution can alter the micro-pore and particle structure of soil, thereby affecting its engineering properties. To investigate the compression characteristics of marine soil under different salt concentrations, one-dimensional compression and SEM scanning tests were conducted on marine reconstituted clay from the Yellow Sea with varying NaCl concentrations (0–5%). The effects of NaCl concentration on the compression characteristics and microstructure of marine sedimentary clay were analyzed. The results indicate that: (1) Compressibility increases up to a NaCl concentration of 2.5%, after which it declines. At 2.5% NaCl threshold concentration, the coefficient of compression, compressibility index, and consolidation coefficient reach their peak values, and the response becomes more pronounced with increasing compression pressure. During the secondary compression stage, as pore water is expelled, the impact of NaCl concentration on compressibility diminishes, while the rebound characteristics remain unaffected by NaCl concentration; (2) SEM analysis reveals that at a NaCl threshold concentration of 2.5%, the pore fractal dimension, particle fractal dimension, pore anisotropy, and particle anisotropy reach their maximum values, with the most complex shape and pores and particles aligning in the same direction. When the concentration is less than 2.5%, the soil exhibits narrow pores and rounded particles upon compression. When the concentration exceeds 2.5%, the microstructure changes in the opposite direction, confirming the particle rearrangement mechanism driven by surface contact under moderate salinity. At the threshold concentration of 2.5%, a balance between electrostatic forces and attractive forces enables stable surface-to-surface contacts, maximizing compressibility. The findings of this study provide valuable references for the foundation design of marine geotechnical engineering in specific sea areas, thereby enhancing the safety and reliability of related projects.

Effect of Straw Characterization on the Mechanical Behavior of Compacted Straw-Reinforced Soils

Straw reinforcement improves the mechanical properties of soil matrices by uniformly incorporating dispersed straw materials, demonstrating advantages in strength enhancement, toughness improvement, and deformation control. This study aims to compare the reinforcement effects of different types of straw on soil and clarify the optimal method for straw-based soil stabilization. For wheat straw-reinforced soil using different processing methods (straw segment, straw powder, and straw ash) and mass contents, the basic geotechnical properties of each mixture were first determined. Triaxial tests were then performed under varying confining pressures and compaction conditions to assess the strength and modulus characteristics of the different reinforced soil specimens, and the microstructural characteristics of fiber-reinforced soil were investigated using scanning electron microscopy (SEM) analysis. The experimental results indicated that the strength and ductility of soils increased significantly with the addition of straw. The optimal performance of straw-reinforced soils occurred at 0.3% content. The elastic modulus increased by 85%, 64%, and 57% under confining pressures of 50 kPa, 100 kPa, and 200 kPa, respectively. At 200 kPa, straw segments provided the highest modulus increase of 57%, while straw ash achieved the greatest strength improvement of 97%. Furthermore, considering both compaction effects and cost efficiency, a compaction degree of 95% is recommended for straw-reinforced soil in engineering applications. Based on scanning electron microscopy, it was observed that the distribution characteristics of different straw types within the soil exhibit distinct patterns. This study aims to provide data to support the efficient utilization of straw materials in engineering applications.

Suggestions for promoting SOC storage within the carbon farming framework: Analyzing the INFOSOLO database

Abstract The new world challenges under climate change call for eco-friendly practices that make agriculture’s economic and social dimensions compatible with environmental preservation and ecosystem resilience. Carbon farming has emerged as an interesting alternative for dealing with these new frameworks, as it promotes conservation agriculture with practices that increase carbon sequestration in soils and plants. Considering these motivations, this research intends to bring more insights into the levels of soil organic carbon (SOC) in the Portuguese context, and this variable is interrelated with land use, land attributes, and soil characteristics. Statistical information from the INFOSOLO legacy database was analyzed through statistical methodologies and machine-learning approaches. The findings provide interesting support for the stakeholders about the influence of land use and soil types on the levels of SOC.

An experimental study of the water-holding and strength characteristics of unsaturated canal embankment soils in the South-to-North water diversion project

The water-holding and strength characteristics of unsaturated expansive soil and modified soil in a high-fill canal embankment along the central line of the South-to-North Water Diversion Project were investigated using a pressure plate apparatus and a GDS unsaturated triaxial test system. The soil-water characteristic curves (SWCCs) of expansive soil and modified soil were obtained by curve-fitting the results of water-holding characteristic tests, thereby revealing the distinctions in water-holding characteristics of the two soil types. The laws governing the effects of matrix suction on the stress-strain relationships and shear strength of the two soil types were explored through unsaturated triaxial drainage shear tests. According to the test results: (1) The moisture content and void ratio of each soil type decreased gradually with the increase in matrix suction, although the void ratio of modified soil decreased at a slower rate than that of expansive soil. (2) Matrix suction induced a transition from strain hardening to strain softening; (3) The shear strength of both soils increases with the matrix suction and confining pressure, with the increment of expansive soil greater than that of modified soil. Notably, the influence of confining pressure became progressively more significant with increasing matrix suction for both soils; (4) The cohesion and internal friction angle of expansive soil and modified soil increases with the matrix suction, with 200 kPa as the critical point of increasing rate; (5) The expansive soil differs from modified soil in cohesion and internal friction angle under different matrix suctions, with matrix suction of 400 kPa as the critical point. (6) The matrix suction thresholds of 200 kPa and 400 kPa can serve as references for engineering design and construction, as well as seepage prevention and slope reinforcement. This study provides technical parameters and theoretical support for the design, construction, and long-term stability of embankments on the expansive soil in the South-to-North Water Transfer Project site.

Topographic and Edaphic Factors Shaping Floral Diversity Patterns and Vegetation Structure of Treeline Ecotones in Kumaun Himalaya

ABSTRACTTreeline ecotones are ecologically sensitive ecosystems that are increasingly vulnerable to recent global warming and land degradation processes such as soil erosion, nutrient depletion, and organic matter loss. However, little is known about how floral diversity in treeline ecotones responds to changing environmental factors, particularly in the high Himalayan treeline ecotones. The present study examined the potential effects of topographic and edaphic factors on the vegetation structure of treeline ecotones of two mountain summits in Kumaun Himalaya. Using line transects, plots, and quadrats, we recorded 96 plant species from 72 genera and 36 families. Jaccard similarity coefficients revealed varying degrees of similarity in species composition between different aspects and elevations. Beta diversity analysis indicated nestedness as a dominant driver of community composition. Vegetation assessments showed shifts in tree density (ranging from 12.50 to 227.50 individuals per hectare), basal area (ranging from 0.138 to 9.855 square meters per hectare), and dispersion patterns along the elevational gradient. The dominant tree species across all treeline ecotone plots was Rhododendron arboreum. Regeneration was evident, with 69% of trees in smaller girth classes, indicating active recruitment. In addition to vegetation distribution, this study analysed soil characteristics across the treeline ecotones to assess potential land degradation trends. Soil temperature, pH, moisture, and water holding capacity decreased with elevation. South and east aspects had higher temperatures, pH, and phosphorus, while north and west aspects had higher moisture, organic carbon, and nitrogen. Results indicate that decreasing soil moisture, increasing bulk density, and declining total organic carbon at higher elevations and exposed aspects are indicative of degradation processes that may impact long‐term vegetation stability. The significant relationships between soil parameters and species distribution highlight the importance of understanding degradation dynamics in shaping floristic patterns. Non‐metric multidimensional scaling (NMDS) showed distinct clusters of treeline plots based on environmental variables (stress value: 0.17), while canonical correspondence analysis (CCA) demonstrated strong species‐environment correlations, explaining 83.08% of the total inertia. Given the observed soil degradation trends, conservation strategies should prioritize soil stabilization, erosion control, and nutrient depletion to mitigate the risks of ecosystem degradation. This research provides key insights into ecosystem resilience and serves as a foundation for monitoring treeline ecotones under changing environmental conditions.

Litter biomass was the main factor driving plant diversity following grazing exclusion in shrub - Grassland ecotone of eastern Qilian Mountains.

Litter biomass was the main factor driving plant diversity following grazing exclusion in shrub - Grassland ecotone of eastern Qilian Mountains.

Shallow groundwater table fluctuations: A driving force for accelerating the migration and transformation of phosphorus in cropland soil.

Shallow groundwater table fluctuations: A driving force for accelerating the migration and transformation of phosphorus in cropland soil.

Spatially explicit heteroskedastic modeling for the Soil Health Assessment Protocol and Evaluation version 1.0S

AbstractGreater awareness of the role of soil management in achieving global production goals and mitigating emerging environmental challenges has focused the spotlight on soil health assessment and interpretation. The role of site‐specific characteristics in soil health assessment has long been recognized through small‐scale experimental studies, and the soil health assessment protocol and evaluation (SHAPE) tool was developed to facilitate cross‐site comparisons and provide regionally relevant interpretation by accounting for site‐specific factors. Specifically, SHAPE version 1.0 was developed to account for primary climate‐edaphic factors including long‐term climate means (temperature and precipitation) and edaphic characteristics (soil texture and soil suborder). Version 1.0S of SHAPE further incorporates a spatially explicit, heteroskedastic approach into the Bayesian linear regression model to refine peer‐group scoring curves and benchmark values based on proximity. This approach captures regional variability in soil characteristics and improves the relevance and interpretability of the SHAPE scores and benchmark values.

Soil Organic Carbon Content and Density in Alpine Meadows of the Tibetan Plateau in Response to Pika Outbreaks Along the Altitudinal Gradient, West China

This study investigated the effects of plateau pika (Ochotona curzoniae) disturbances and altitude on soil organic carbon (SOC) storage characteristics, including SOC content and density (SOCD). In this study, plateau pika outbreak areas and non-outbreak areas at different altitudes were compared in terms of vegetation biomass, soil physicochemical properties, and soil organic carbon content (SOC) and density (SOCD) to establish the relationship between vegetation and soil characteristics (including soil organic carbon content and density). The results showed that soil total nitrogen (TN) content decreased significantly (p < 0.01) with elevation in both plateau sage grouse outbreak and non-outbreak areas, and SOC and SOCD decreased significantly (p < 0.01) in plateau sage grouse outbreak areas, but SOCD increased first and then decreased with elevation in non-outbreak areas. There were significant differences (p < 0.05) in total phosphorus (TP) at low elevations and nitrate nitrogen (NO3−-N) at high elevations between outbreak and non-outbreak areas, but other nutrients did not differ hugely between outbreak and non-outbreak areas at the same elevation. Correlation analysis revealed that belowground biomass (BGB) in the plateau pika outbreak area was strongly significantly positively correlated with SOC (p < 0.01); structural equation modeling (SEM) analysis revealed that altitude in the plateau pika outbreak area had a direct effect on SOC (path coefficient = −0.882, p < 0.001), but altitude had a reduced influence on SOC and SOCD in the non-outbreak area; nitrate nitrogen in the plateau pika outbreak area and total nitrogen (TN) were the key influencing factors, which exerted a strong direct influence on SOC and SOCD (path coefficient = −0.666 and 0.639 (p < 0.001), respectively). Therefore, increasing vegetation biomass and nitrogen nutrient content through reseeding pasture and fertilization can facilitate the accumulation and recovery of SOC and SOCD in the ecological restoration of degraded alpine meadows, and it is especially important to quickly enrich soil nitrogen content in the outbreak area of plateau pika populations at high altitudes.

Comparing the Value of Natural Capital in South Australian Farmland Using Market Sales and Assessed Valuation

ABSTRACTThe hedonic valuation method is used to estimate the value of different forms of natural capital (i.e., specifically native vegetation but also soil characteristics, drought, climate and location) on farmland by farm size and industry in South Australia, using agricultural property market sales and assessed value estimates from 2000 to 2013. As expected, higher farmland values were consistently associated with more favourable soil characteristics; higher rainfall; proximity to coast; urban accessibility; higher built‐in land production; and a non‐linear effect (an inverse U‐shape) for maximum temperature. Interestingly, contrasting results were found between native vegetation values estimated using market sales and assessed valuations. An increase in the proportion of native woody vegetation was significantly associated with the per hectare market sale price but at a decreasing rate when the vegetation increased above a third of the property. This contrasts with the assessed values database, where cleared land (decreasing vegetation) was valued higher (but at a diminishing rate). The sales prices of small and medium‐sized farms reflected higher values per hectare for native vegetation than large farms—while native vegetation was associated with higher values for grazing and horticulture farm market sales than for cropping farms. The results suggest that, where market sales information is unavailable, assessed valuations may not be effective indicators of native vegetation values—as assessed evaluations tend to undervalue native vegetation on farmlands.

Synergistic interplay of management practices and environmental factors in shaping grassland soil carbon stocks: Insights into the effects of fertilization, mowing, burning, and grazing.

Synergistic interplay of management practices and environmental factors in shaping grassland soil carbon stocks: Insights into the effects of fertilization, mowing, burning, and grazing.

Geotechnical characteristics of clayey soil stabilized with fly ash and marble dust

Geotechnical characteristics of clayey soil stabilized with fly ash and marble dust

Compaction Characteristics of Biopolymer-Amended Nonplastic Soils

Compaction Characteristics of Biopolymer-Amended Nonplastic Soils

Analysis of Cyclic Shear Characteristics of Coarse-Grained Soil Reinforced with Geogrids

Analysis of Cyclic Shear Characteristics of Coarse-Grained Soil Reinforced with Geogrids