J.S. Ogeh

Soil carbon storage is a key component of the global carbon cycle and plays a vital role in climate regulation, particularly within forest ecosystems. This study assessed soil organic carbon (SOC) and associated soil properties in a teak (Tectona grandis) plantation at the University of Benin, Edo State, Nigeria. A plot measuring 50 m × 50 m was marked out in the plantation and divided into three sections to represent replicates, with two plots each, resulting in six georeferenced sampling points which include USS1 - USS6 (Uniben Soil sample). Soil samples were collected from the top 0–15 cm layer, processed, and analyzed for physical and chemical properties, Standard laboratory procedures were followed, and results were subjected to statistical analysis using ANOVA. Results revealed significant differences (p ≤ 0.05) among plots and replicates in most soil properties. SOC and organic matter were highest in USS1 and USS4, indicating greater litter input and reduced decomposition, while USS3 recorded the lowest values alongside higher bulk density and exchangeable acidity. Total nitrogen and exchangeable cations followed SOC patterns, reflecting the close linkage between carbon and nutrient dynamics. USS2 and USS5 showed relatively higher total nitrogen and cation exchange capacity, suggesting better nutrient retention. Available phosphorus remained low across all sites, indicating potential nutrient limitation. Soil pH and electrical conductivity varied significantly among sampling points, highlighting micro-site differences influenced by litter accumulation, root activity, and localized decomposition. Soil texture showed no significant variation, confirming uniform parent material. Overall, the results demonstrate that teak plantations enhance soil organic carbon and nutrient status, contributing to carbon sequestration and sustainable land management, while localized conditions drive variations in soil fertility and nutrient distribution.

Habanero pepper (Capsicum chinense Jacq.) is an important horticultural crop in Nigeria, but its yield potential is constrained by poor soil fertility and unsustainable tillage practices. This study was undertaken to evaluate the effects of tillage practices and nitrogen fertilizer application rates on performance of Habanero pepper under field conditions in Benin City, Edo State, Nigeria.
The field experiment was a 2 × 4 factorial arrangement fitted into a randomized complete block design with four nitrogen fertilizer rates (0, 40, 80, and 120 kg N/ha) and two tillage systems (minimum tillage and no-tillage) with three replications. Composite soil samples were collected and analyzed for physical and chemical properties before and after planting. Agronomic data collected includes plant height, number of leaves, number of branches, stem girth, and yield. Nutrient uptake, nutrient use efficiency (NUE), and nutrient balance sheets were used to assess fertilizer responsiveness.
Results showed that nitrogen application significantly affected soil pH, organic matter, and nutrient availability, with high N rates (120 kg/ha) resulting to acidification and organic matter decline. Minimum tillage enhanced nutrient uptake and plant growth compared to no-tillage. Optimal plant growth and yield were achieved under the interaction of minimum tillage and moderate nitrogen rates (40 and 80 with yield values of 4.42t/ha and 4.16t/ha respectively). NUE peaked at 40 kg N/ha and declined at higher rates, while nutrient balance sheets indicated surplus nitrogen with increased N inputs (120kg/ha). The study suggests that integrating 40–80 kg N/ha with minimum tillage optimizes Habanero pepper growth, yield, and soil quality and NUE, excessive N application should be avoided to promote healthy soil environment and ensure sustainable vegetable production systems in Nigeria.