Assessing Soil Property Variability in Nigerian Savannas: Land‐Use Differences Under Recurrent Bush Burning

ABSTRACT

Understanding the spatiotemporal variability of soil properties is critical for designing effective land management strategies in heterogenous agroecosystems. This study assessed soil property variability across four land management systems—conventional arable, biochar‐amended arable, fallow/grazing, and teak plantation—within the Guinea Savanna region of Nigeria, where landscapes are subject to recurrent seasonal bush burning. Composite topsoil samples (0–20 cm) were analysed for key physicochemical properties including pH, exchangeable acidity (EA), effective cation exchange capacity (ECEC), total nitrogen (TN), soil organic carbon (SOC), available phosphorus (AvP), exchangeable bases, and selected micronutrients. Analyses of variance and correlation analyses indicated significant differences among land management systems for TN, iron availability, ECEC, and pH, whereas SOC and AvP showed no significant variation. Across systems, soils were near neutral in reaction and exhibited moderate SOC levels (0.67%–0.72%). Available P ranged from 7.59 mg/kg in biochar‐amended soils to 12.35 mg/kg in plantation soils. The fallow system recorded the highest TN (0.13%), exchangeable K ⁺ (0.7 cmol(+)/kg), and ECEC (4.2 cmol (+)/kg), indicating relatively greater nutrient retention capacity. Given that all sites experience similar seasonal burning regimes, the observed differences primarily reflect land‐use effects within a shared fire‐affected landscape rather than direct impacts of burning. The lack of significant SOC differentiation across systems suggests convergence in soil carbon levels despite contrasting land uses, potentially indicating that recurrent disturbance constrains organic matter accumulation. These findings underscore the need for integrated land management strategies that reduce reliance on frequent burning while enhancing organic matter inputs—such as residue retention, agroforestry integration, and improved fallow systems—to rebuild soil carbon stocks and sustain soil fertility in savanna agroecosystems.