Fine-textured postglacial soils in Sweden commonly exhibit elevated total concentrations of cobalt (Co) and nickel (Ni), occasionally exceeding guideline values for sensitive land use. However, the environmental relevance of these exceedances remains uncertain. In this study, 26 soil samples from 23 sites were analysed to assess the mineralogical origin, geochemical reactivity, and solubility of Co and Ni. Quantitative X-ray powder diffraction showed strong associations between total metal concentrations and phyllosilicate minerals, particularly chlorite, trioctahedral smectite, and trioctahedral mica, indicating a predominantly minerogenic origin. The geochemically active fraction, determined by 0.43 M HNO3 extraction, averaged 22.8% for Co and 12.5% for Ni, confirming the dominant role of phyllosilicate-bound Co and Ni and the associated low reactivity. Dissolved concentrations in 0.001 M CaCl2 were very low, resulting in exceptionally high distribution coefficients for metal desorption (Kd), with geometric means of 285,000 L kg−1 for Co and 23,100 L kg−1 for Ni when total metal contents were used. Multisurface geochemical modelling using Visual MINTEQ successfully reproduced Ni solubility in non-calcareous soils but substantially overestimated Co solubility across a wide pH range, suggesting that key retention mechanisms for Co, possibly involving Mn oxides and redox processes, are not adequately represented in current models.Overall, the results indicate that Co and Ni in these soils have very low mobility and limited environmental risk despite elevated total concentrations. The findings highlight the importance of considering geochemical reactivity and mobility, rather than total concentrations alone, in environmental risk assessment and soil management.
Nigeria encompasses environmental gradients that generate substantial variation in soil genesis, morphology, classification and spatial distribution. This scoping review synthesized evidence on soil-forming factors, ecological distribution, parent materials, profile morphology, classification, spatial variability and degradation across Nigerian landscapes. Searches of databases and repositories identified 231 records. After duplicate removal and screening, 131 full-text reports were assessed, and 96 sources were included in accordance with PRISMA-ScR. Narrative synthesis was applied because study designs, sampling strategies, classification systems and spatial coverage were heterogeneous. The evidence shows that climate, parent material, relief, organisms and time interact with hydrology and land use to control weathering, horizon development, texture, structure, drainage and redoximorphic features. Nigerian studies document Alfisols, Ultisols, Inceptisols, Entisols, Oxisols and Vertisols, although their reported occurrence varies among landscapes and does not establish continuous ecological-zone dominance. Floodplains and coastal lowlands exhibit stratification, mottling and gleying associated with alluvial deposition and fluctuating groundwater. USDA Soil Taxonomy and WRB provide distinct diagnostic frameworks and require separate interpretation. Erosion, nutrient depletion, seasonal waterlogging and petroleum contamination represent geographically differentiated degradation pressures. GIS, remote sensing and digital soil mapping have improved spatial assessment, but legacy reconnaissance data, uneven profile coverage and limited independent validation constrain national interpretation. Renewed profile surveys, harmonized descriptions and validated spatial models are central to improving Nigerian soil information and supporting landscape-specific management.
Quantifying structural heterogeneity and soil particle-size distributions (PSDs) along semi-arid toposequences is critical for understanding pedogenesis, aggregate stability, and carbon dynamics. Traditional textural metrics and single-fractal models often smooth over multi-scale matrix reorganisation. This exploratory study applied both fractal and multifractal computational analysis to high-resolution laser diffraction PSD datasets across three soil profiles along a semi-arid toposequence in Mosu, Botswana. Single-fractal dimensions (Dv), generalised dimension spectra (Dq), and singularity spectra (f(α)) were combined with physical properties, soil organic carbon (SOC), electrical conductivity (EC), and aggregate stability indicators (MWD and WSA). Analysis of covariance revealed a significant, uniform depth-dependent increase in Dv (2.31–2.63; p < 0.001), driven by vertical clay illuviation (r = 0.97), with topographic position setting baseline textural offsets. All horizons had non-linear, sigmoidal D(q) curves and concave f(α) spectra. Structural differentiation was primarily influenced by sparse, low-density particle domains (q < 0), whereas dense fine-particle matrices (q > 0) maintained stable scaling across profiles. Measure dispersion ratios (D1/D0 = 0.75–0.87) coupled inversely with singularity spectral widths (Δα = 0.833.06; r = −0.71). Subsurface illuvial clay packing homogenised measure dispersion (0.87), suppressing micro-aggregate slaking (WSA < 0.25 mm; r = −0.84) and enhancing macro-aggregate stability (MWD up to 2.76 mm, co-regulated by SOC (r = 0.82). Spectral asymmetry (Δf = −0.32 to +0.36) successfully distinguished fine-matrix illuviation (Δf < 0) from multi-scale structural complexity induced by salinity (EC up to 620 mS/m; Δf > 0, Δα > 2.40). These results demonstrate that multifractal parameters, particularly Δα and Δf, have a potential to provide sensitive, non-destructive diagnostic proxies that separate true pedogenic development from simple textural fineness in semi-arid environments.
Lime application under no-till alters phosphorus (P) dynamics by promoting surface P accumulation, whereas incorporation may redistribute nutrients and soil organic carbon throughout the profile. However, how lime rate and application method jointly affect soil P fractions in highly weathered subtropical soils remains poorly understood. This study evaluated soil P fractions under no-till and conventional management following lime reapplication. The experiment was established in 2023 in Paraná State, Brazil, on a subtropical Oxisol using a randomized block design in a 4 × 2 factorial scheme. Treatments consisted of four lime rates equivalent to 0, 1.0, 1.3, and 1.6 times the recommended rate to achieve 70% base saturation, applied on the soil surface without incorporation or incorporated into the 0–20 cm layer. Soil P fractionation was performed in the 0–5, 5–10, and 10–20 cm layers nine months after liming. Most effects occurred in the 0–5 cm layer, where the recommended lime rate under surface application increased soluble and available P (Mehlich-3). In contrast, incorporation reduced available and pseudo-total P, defined here by oxidative acid digestion. Regardless of management, increasing lime rates decreased inorganic P throughout the 0–20 cm profile, while increasing organic P in the 0–10 cm layer and HCl-extractable P at the surface. Principal component analysis associated surface liming with greater soil organic carbon, pH, and P accumulation across fractions. Liming modified P cycling mainly through redistribution among soil fractions rather than by increasing immediately available P.
Southeastern Australia encompasses temperate to semi-arid climatic zones and supports agricultural and pastoral systems. Periodic droughts have imposed substantial financial, social, and psychological burdens on farming communities, highlighting the need for improved drought and agricultural risk management. These impacts underscore the importance of soil moisture, a key variable for monitoring, hydrologic and climate modelling, and seasonal forecasting. However, obtaining soil moisture observations across depths with sufficient spatial and temporal resolution remains challenging. Current information sources, including in-situ monitoring networks, satellite remote sensing products, and land surface model outputs, provide unique advantages but are constrained by uncertainties and limitations. In-situ networks provide valuable depth-specific measurements at targeted sites, supporting agricultural decision-making and calibration and validation of remote sensing and model-based products. Despite their importance, a systematic synthesis and assessment of soil moisture monitoring networks in southeastern Australia is lacking. This knowledge gap limits researchers, practitioners, and policymakers seeking to understand network characteristics, data availability, and opportunities for improved data integration. This review addresses this gap by documenting and summarising key in-situ soil moisture monitoring networks relevant to southeastern Australia and highlighting their complementary value for data applications. The review identifies key challenges, including differences in measurement protocols, calibration approaches, spatial representativeness, data accessibility, and long-term operational sustainability. It also discusses future priorities for improved network design, standardisation, and integration with satellite and modelling products. Overall, this paper highlights the potential of coordinated monitoring and data integration to maximise in-situ soil moisture observations, supporting agricultural, hydrological, and climate-resilience applications in southeastern Australia.
