The climate change–driven reshuffling of floristic elements has recently gained attention, yet the mechanistic bases of these shifts remain poorly understood. Here, we examined how variation in soil chemical characteristics associated with an elevational gradient influences the early performance of lowland widespread plant species under controlled conditions. We tested the performance of two plant species (Trifolium pratense L. and Sisymbrium loeselii L.) using soil samples collected from different elevational zones of the Kashmir Himalaya in a greenhouse experiment. We observed limited trait development in S. loeselii under greenhouse conditions, which reduced the strength of interspecific comparisons; therefore, most trait responses, except plant height, were primarily driven by T. pratense. Generalized linear mixed models indicated that soil origin along the elevational gradient and associated nutrient variation, especially phosphorus, were linked to delayed germination, reduced leaf count, and lower plant height, whereas nitrogen, potassium, and sulphur showed trait-specific associations with measured plant responses. Overall, early plant performance tended to decline in soils originating from higher elevations under controlled greenhouse conditions. These findings suggest that soil nutrient variation may influence early plant performance across contrasting elevational soils, while highlighting the need for field-based studies to evaluate the ecological relevance of these patterns under natural environmental conditions.
Diuron is a widely used herbicide in sugarcane, cotton, coffee, and citrus production and is classified as a priority pollutant. Physical and chemical remediation of pesticide-contaminated sites is often technically complex and costly. Microorganism-mediated bioremediation offers an environmentally compatible and cost-effective alternative, particularly when pollutant-specific indigenous microorganisms are used. In this study, microorganisms were isolated from diuron-amended soil microcosms, and their diuron removal capacities were evaluated under different pH and temperature conditions. Fourteen bacterial isolates were initially screened, of which six capable of growing in diuron-supplemented medium were selected. Isolates 2 and 6 achieved the highest removal efficiencies, reaching 53% and 51%, respectively, within 3 days. A mixed microbial culture achieved 60% removal, suggesting potential complementary interactions among the isolates. Based on 16S rRNA gene sequencing, isolate 2 showed 97–99% sequence identity to Bacillus sp., whereas isolate 6 showed 97–99% identity to Cellulomonas sp. The study aimed to identify bacterial strains with potential application in future pesticide bioremediation. Indigenous isolates with high pollutant-removal capacity may improve bioremediation performance in their native environments because they are adapted to prevailing local conditions.
This study investigated the spatial variability of DTPA-extractable Fe, Mn, Zn, and Cu in a cultivated field, their relationships with selected soil properties, and the optimum number of samples required to estimate mean micronutrient concentrations precisely. Forty-nine soil samples were collected at 5-m intervals from a square grid within a 30 × 30 m cultivated plot. Mean DTPA-extractable concentrations were 71.80 mg kg⁻¹ for Fe, 350.26 mg kg⁻¹ for Mn, 2.58 mg kg⁻¹ for Zn, and 4.11 mg kg⁻¹ for Cu. The coefficients of variation were higher for Fe (20.6%) and Zn (19.2%) than for Mn (11.8%) and Cu (8.4%). Spatial variability was best described by spherical models for Fe and Mn and exponential models for Zn and Cu. The spatial correlation ranges followed the order Zn (67 m) > Cu (17 m) > Fe (15 m) > Mn (8 m). Nugget-to-sill ratios indicated strong spatial dependence for Fe (0.039%), Mn (8.03%), and Cu (11.32%) and moderate spatial dependence for Zn (42.86%). In principal component analysis, Fe, Cu, and soil organic matter (OM) had high negative loadings on PC1, whereas Zn contributed most strongly to PC2. Fe was positively correlated with soil OM and negatively correlated with Mn, Zn, pH, Ca, and Na. Mn was positively correlated with Zn and Cu, whereas Zn was positively correlated with silt and pH. Cu was negatively correlated with pH, Ca, Mg, and K. The numbers of samples required to estimate mean concentrations within allowable errors of 5%, 10%, and 20% followed the order Fe (69, 17, and 4) > Zn (59, 15, and 4) > Mn (23, 6, and 2) > Cu (11, 3, and 1), respectively. Thus, greater spatial variability in a micronutrient requires a larger sample size to estimate its field mean precisely.
Limited information is available on the pedology of highly weathered soils derived from ophiolitic rocks in the Philippines. This study evaluated red, highly weathered soils across the ophiolitic landscape of Eastern Samar. Five soil profiles were described and sampled for laboratory analysis. The geochemical composition of the parent materials ranged from mafic to ultramafic. The soils were acidic [pH(H₂O) = 4.97–6.45; pH(CaCl₂) = 3.95–5.96] and contained low concentrations of available P (trace–1.14 mg kg⁻¹), exchangeable K (trace–0.23 cmolc kg⁻¹), Ca (trace–12.66 cmolc kg⁻¹), and Na (trace), together with low Ca/Mg ratios (0.1–41.7). Profile 2 had comparatively high exchangeable Ca concentrations, particularly in deeper horizons. Ca/Mg ratios increased with depth in Profiles 2 and 3 but decreased in Profile 5. In Profiles 1 and 4, Ca/Mg ratios were very low and could not be calculated in several subsurface horizons because exchangeable Ca and/or Mg occurred at trace levels. Extractable Ni concentrations ranged from 0.16 to 22.40 mg kg⁻¹, with the highest concentration occurring in the Bo2 horizon of Profile 4, indicating contributions from ultramafic materials, Ni accumulation, and adsorption onto Fe (oxyhydr)oxides during weathering. The warm, humid climate, highly weatherable ophiolitic parent material, stable, well-drained topography, and original rainforest vegetation promoted the formation of highly weathered Ultisols and Oxisols. Low OM (0.36%–3.60%) and total N (0.04%–0.25%) contents may reflect anthropogenic effects, particularly periodic burning associated with shifting cultivation. The CIA (55.56–99.31), CIW (55.63–99.58), MWPI (0.14–7.44), and Vogt ratio (1.08–63.95) indicated advanced weathering and substantial losses of major cations. These findings demonstrate that ophiolitic soils under humid tropical conditions undergo intense weathering and leaching, resulting in marked profile-scale variation during pedogenic development.
Soil structural and hydraulic properties are fundamental for regulating water retention, aeration, saturated hydraulic conductivity (Ks), and root development in perennial cropping systems. This study evaluated the spatial variability of soil physical properties in tea plantation systems developed along contrasting alluvial geomorphic settings in northern Vietnam. The study was conducted along a representative alluvial toposequence in Tan Cuong commune, Thai Nguyen province, including riverside lowlands, previous dikes, and older hillslope positions. Three tea garden sites (TB1, TB2, and TB3) and two adjacent forest sites planted with Acacia spp. (FB1 and FB3) were investigated along the toposequence. An additional tea garden site (TS1) located in Dong Hy commune was included as a comparative site representing a less favorable tea-growing environment developed on different parent materials. Soil samples were collected at two depths (0–10 and 20–30 cm) in triplicate using undisturbed and bulk soil samples for the determination of bulk density, three phase distribution, Ks, aggregate stability expressed as mean weight diameter (MWD), and soil water retention characteristics. The results revealed pronounced differences among sites, depths, and land-use types. Riverside alluvial soils (TB1 and FB1), developed from coarse-textured quartz-rich deposits, exhibited lower MWD values, weaker water retention, and lower structural stability. In contrast, soils located on previous dikes and weathered hillslopes (TB2, TB3, FB3, and TS1) showed higher aggregate stability, more differentiated pore systems, and greater water-holding capacity. At the 20–30 cm depth, TB3 exhibited significantly higher Ks, MWD, and plant-available water than TB1 and TB2 (p < 0.05), indicating more favorable structural and hydraulic conditions. Forest soils generally maintained higher aggregate stability and greater gaseous porosity than adjacent tea soils. The findings demonstrate that soil structural and hydraulic properties in tea plantation systems were closely associated with geomorphic position, pedogenic development, and land use along tropical alluvial toposequences.
