SOIL

Soil stabilization refers to the process of improving the engineering properties of soil through physical, chemical, or mechanical means to make it more suitable for construction purposes. In this study, the geotechnical properties of lateritic soil collected from the Ovia North East Local Government Area of Edo State were evaluated to determine the effect of rice husk ash (RHA) as a stabilizing agent. The study was prompted by observed pavement and foundation failures within the study area, which were attributed to the poor strength and instability of the underlying lateritic soils. Rice husk ash, an agricultural waste generated from the combustion of rice husks, was utilized in this research to promote sustainable waste management while improving soil performance. The soil samples were mixed with varying proportions of RHA at 2%, 4%, 6%, 8%, and 10% by dry weight of soil. Laboratory tests including sieve analysis, specific gravity, Atterberg limits, compaction, and California Bearing Ratio (CBR) tests were conducted to evaluate the impact of RHA on the soil’s mechanical and index properties. Results showed that the inclusion of RHA led to improvements in the maximum dry density (MDD) and optimum moisture content (OMC), with noticeable increases in CBR values compared to the untreated samples. However, the results also indicated that RHA alone exhibits limited potential as a stabilizing material at higher percentages. The optimum performance was recorded at 5% RHA content, which provided the best balance between strength and workability. Therefore, the use of 5% RHA is recommended for field stabilization of lateritic soils intended for pavement sub-base construction. Furthermore, to achieve better pozzolanic activity, it is advised that RHA used for stabilization be calcined at a controlled temperature range of 600°C to 700°C, as supported by Alabi et al. (2015)

This study examines the influence of maize cultivation on weed diversity and abundance in a ferruginous soil. A potted experiment was conducted to assess the effects of varying maize densities and soil iron amendments on weed population dynamics. The results indicate that increasing maize density significantly reduces weed population through competition for essential resources such as light, water, and nutrients. Conversely, soil iron amendments had a dual effect, with lower iron concentrations suppressing weed growth and higher concentrations favoring the proliferation of iron-tolerant species. The analysis of variance (ANOVA) revealed statistically significant differences in weed populations across the different treatments (F = 7.99, p = 0.00117 for maize density; F = 6.27, p = 0.0169 for iron amendments), confirming the substantial impact of these factors. These findings align with previous research on crop competition and nutrient-mediated weed dynamics. The study highlights the importance of optimizing maize density and soil nutrient levels as an integrated weed management strategy.

The fundamental geotechnical parameter for stability of all Civil Engineering structures, such as foundations and slopes, is soil shear strength, shear strength is governed by Mohr- Coulomb failure criterion. Current standard geotechnical practice often uses a limited and a conventional range of 100KN/m2, 205KN/m2 and 310KN/m2, Extrapolating the failure envelope obtained from this narrow, limited range to low or high in-situ stresses can introduce significant error into geotechnical design, leading to unsafe structure. This study investigates the shear strength characteristics of soil samples collected from Ogbowo, Ekosodin village, Edo State, Nigeria, through a comparative analysis of standard and extended cell pressure applications. Soil specimens were prepared from five different samples to get the accurate values of Angles of internal friction and cohesion by drawing the Mohr circle using the standard and extended cell pressure, to evaluate how extended cell pressure configurations influence the determination of soil shear strength compared to convention testing method. The analytical results reveal that the soil at the study site is predominantly fine-grained, characterized by critically low angles of internal friction, which indicates minimal frictional resistance and a reliance on cohesive bonding for shear strength. Comparative analysis consistently demonstrates that cohesion values derived from the standard triaxial testing approach (15,13,12,28 and 19kN/m2 respectively) are significantly higher than those obtained through the extended nine-cell pressure range (2,5,6.4,8,12kN/m2 respectively). While the extended pressure testing resulted in an increases in the angle of internal friction. for the standard cell pressure (0.57º, 4.15º,4.29º,1.43º,1º and those of the extended cell pressure 2.43º, 3.89º, 4.41º, 5.71º, 2.63º respectively). it simultaneously caused a substantial reduction in cohesive strength. Consequently, this research concludes that the standard geotechnical engineering cell pressure range provides a more reliable and higher estimation of soil shear strength for the studied site. The findings suggest that the use of extended cell pressures may underestimate the short-term stability of the soil, making the conventional standard triaxial method more appropriate for site-specific geotechnical design and analysis.

This study focused on isolating and identifying fungal species associated with agricultural farmland soil in UNIBEN. Soil samples were collected in sterile plastic ziplock bags from selected agricultural farmlands in Benin City, Edo State, and were subsequently transported to the laboratory for fungal identification. The identification of fungal isolates was conducted using cultural and morphological methods. The results indicated that total fungal counts of soil samples collected from the selected farmlands ranged from 5.70±0.42 to 12.50±1.56. The highest fungal counts were observed in Farm 2 (12.50±1.56), followed by Farm 5 (8.70±0.71), while Farm 4 exhibited the lowest count at 5.70±0.42. The identified fungal isolates included Aspergillus niger, Trichoderma sp., Penicillium sp., Rhizopus arrhizus, and Mucor mucedo. The percentages of occurrence for these fungal isolates varied from 7.14% to 28.57%. Aspergillus niger had the highest occurrence rate at 28.57%, followed by Trichoderma sp. and Penicillium sp., each at 21.43%, while Rhizopus arrhizus had the lowest occurrence at 7.14%. This study emphasizes the importance of understanding the dynamics of fungal populations within these agricultural soils to inform management strategies aimed at enhancing soil health. By monitoring these microbial communities, farmers at these sites can adopt more effective agronomic practices that capitalize on beneficial fungi while minimizing the impact of pathogenic species.

This research work was conducted in the University of Benin, Benin City, with the aim to determine plant nutrient status under different land use types within the Ugbowo campus of the University of Benin, Benin City, Edo State, Nigeria. Soil samples were collected from twelve (12) sites, (three each) from four (4) different land use types, namely: Arable land, Fallow land, Grazing land, and Forest land at depths of 0-15 cm and 15-30 cm. Soil samples from same land use and same depth were bulked to make composite samples which were taken to the laboratory for analysis using standard procedures. Some of the parameters analyzed for are, the Soil pH, Total Organic Carbon (TOC), Total Nitrogen (N), Available Phosphorus (P), Exchangeable Acidity, Exchangeable Base (BS), particle size distribution, Electrical conductivity, Potassium (K) calcium (Ca), Magnesium (Mg) and Effective Cation Exchange Capacity (ECEC). Results showed that the top soils belong to the textural class of loamy sand. Sand content decreased with depth in all land uses while clay content increased with depth. pH was least in arable land, having pH 4.93 and highest in grazing area, having pH 6.2. pH decreased with depth in all land uses except in grazing area, where it increased. TOC, N, P, K, Ca, Mg, Na and sand content, all had their highest values in the top 15 cm of the soils but decreased down the profile while H, Al, and clay values increased with depth

This study investigated the response of soil fungi to various organic amendments; earthworm cast (EC), poultry manure (PM), and inorganic fertiliser (urea) and their impact on the growth of amaranth (Amaranthus cruentus L. The experiment aimed to bridge the knowledge gap regarding the effects of organic amendments on fungal communities and their potential benefits for sustainable amaranth production. The experiment was done using a complete randomised design (CRD) and replicated three times, using soil and a plastic container. Results showed that organic amendments significantly influenced the composition of soil fungal communities compared to the control treatment. Notably, Trichoderma spp., a fungus with high phosphate solubilization potential, was most abundant in urea-amended soil. However, poultry manure (PM) treatment yielded plants with the highest fresh and dry matter weight, likely due to increased nutrient availability and microbial activity stimulated by the breakdown of organic matter. The study showed that PM amendments improved soil health, promoting the growth of beneficial fungi like Trichoderma spp., and enhancing amaranth growth, potentially contributing to sustainable agricultural practices