Effects of Fire on Physical and Chemical Properties of Soil in Fwangnin Bokkos District, Nigeria

Abstract

Background: Vegetation burning, a common agricultural practice, has both positive and negative effects on soil fertility. Soil quality, which is critical for ecosystems, shapes biodiversity and productivity, while increased temperatures from vegetation burning can alter conditions for seed germination by reducing nutrient availability. Objectives: The study aims to assess the impacts of vegetation burning on soil fertility in Fwangnin, Bokkos, Nigeria, through experimental investigation of the effects of burning on both the chemical and physical properties of soil. The results are expected to contribute to the development of adaptive fire management strategies in land use, and the results will also help monitor soil changes in order to maintain long-term soil fertility. Methods: Using purposive sampling, four 500-gram soil samples were taken from 0 – 15 cm depth in burned and unburned areas. The samples were analysed for pH, electrical conductivity (EC), organic carbon (OC), organic matter (OM), nitrogen (N), phosphorus (P), and cation exchange capacity (CEC). Traditional well-proven methods were used for the analysis. Results: It was found that the pH of the burnt soil samples ranged from 6.10 to 5.90, while that of the unburnt samples ranged from 5.73 to 5.81; a significant increase in pH occurs at higher combustion temperatures, which increases the alkalinity of the soil due to the alkaline properties of ash. The electrical conductivity value for the samples in the burnt areas was significantly higher (0.08 mS/cm and 0.10 mS/cm) compared to the healthy soil (0.07 mS/cm and 0.09 mS/cm), which can be explained by the release of mineral ions due to the combustion of organic matter. The study found a decrease in organic carbon content in the burnt soil, a significant deficiency of nitrogen and a decrease in the cation exchange capacity, which contributes to the depletion of the fertile layer and a decrease in the ability of the soil to retain essential nutrients. Increased levels of organic phosphorus were also found in burnt soils, which contributes to improved crop growth and increased yields in the short term. Conclusion: The current study has filled the gap in deep understanding of the impact of vegetation burning on the fertile properties of agricultural soils. Namely, it has been experimentally established and confirmed by the results of similar studies and statistical analysis that while vegetation burning remains a common agricultural practice in Fwangnin, the long-term implications for soil fertility, structure, and ecosystem health are significant. The soil degradation observed in this study suggests that continued reliance on burning as a land-clearing method may undermine agricultural productivity and environmental integrity over time.

Keywords

• agricultural practice
• soil fertility
• thermal effects
• degradation
• granulometric composition
• nutrients